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2024,70(1):0-0, DOI:
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2024,70(1):1-8, DOI: 10.16509/j.georeview.2023.09.015
Abstract:
Satellite gravity field data and wavelet multi- scale analysis methods were used to image the three- dimensional density structure of the Africa Great Rift, and the density disturbance images on multiple depth- equivalent layers of the crust and upper mantle of the Valley were obtained, which provided important supporting evidence for the study of the lithospheric structure and Earth dynamics. The results show that the western rift branch of the middle section of the East African Rift Valley is homologous to the mantle- source melt of the eastern rift valley, but the western branch is not fully developed with later formed time. The kinetic mode of the Great Rift Valley is a tree- shaped bifurcation mode of melt- and- fluid upwelling, which includes: ① low- density fluid swells up in a large area of the asthenosphere; ② the melt- and- fluid continues to surge up in the lithosphere, partially converted into basic magma, and the plane area shrinks; ③ after entering the earth's crust, the upwelling molten fluid bifurcates into multiple branches, and the total plane area is further reduced; ④ the melt—fluid only moves in the rift zone after the upsurge to the upper crust, reflecting the volcanic chain and basalt belt.
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HUI Guanzhou, NIU Chengmin, YANG Chuanchao, ZHANG Jiangtao, GUAN Chao, WANG Mingchun, ZHAO Jing
2024,70(1):9-19, DOI: 10.16509/j.georeview.2023.09.011
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The buried hill strike-slip transfer zone is widely developed in the Bohai Sea, but its development characteristics and reservoir control are weak. Based on drilling, logging, 3D seismic and other data, the development characteristics, genetic mechanism of structural transfer zone and their control effect on buried hill scale reservoirs in northern Liaodong Bay are analyzed. Study shows that under the background of sinistral strike-slip at the late Yanshanian, many types of transfer zones are developed in buried hills in northern Liaodong Bay; based on the interaction of strike-slip faults and the shape of the transfer zone, the buried hill transfer zone in northern Liaodong Bay can be divided into two types: single-branch bending type and bi-branch overlapping type; based on the local stress state, it can be further subdivided into 4 subclasses: single-branch anti "S" type, single-branch "S" type, bi-branch left-handed right-order and bi-branch left-handed left-order transfer zones. Among them, single branch anti "S" type and bi branch left-handed right-order transfer zones belong to pressurized transfer zones, and single branch "S" type and double branch left-handed left-order transfer zones belong to pressure relief transfer zones; the compressive torsional dynamic crushing provided by the pressurized transfer zone makes the buried hill develop large-scale fractured reservoir, which is the key to the development of large-scale buried hill reservoir.
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BAI Daoyuan, WEI Fanghui, LI Bin, ZENG Guangqian, SUN Ji, ZHOU Chao
2024,70(1):20-43, DOI: 10.16509/j.georeview.2023.08.045
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The Yanlinsi gold field is located in the south of the northeastern Hunan gold mining area, where a large number of small and medium- sized gold deposits are developed. Predecessors have not explored and analyzed the kinematic characteristics, formation ages and mechanisms of various types of deformations including ore- controlling structures in the area, affecting a comprehensive understanding of the formation and preservation laws of ore deposits. In view of this, based on the regional structural characteristics and detailed analysis of a large number of surface outcrop structures, the authors determined the deformation sequences and their ages of the Yanlinsi gold field and its adjacent areas, and then combined with deposit geology and isotope dating, discussed the mineralization ages and attributes of ore- controlling structures. The main achievements are as follows: ① The study area has experienced 9 tectonic events from early to late such as regional NW—SE compression in the middle Neoproterozoic, NW—SE compression in the early Silurian, active emplacement and compression of granite bodies in the late Silurian, NW—SE compression in the late Middle Triassic, NNW—SSE to S—N compression in the Late Triassic, NWW—SEE to E—W compression in the late Middle Jurassic, NW—SE extension in the Cretaceous, NE—SW to NNE—SSW compression in the middle—late Paleogene and NW—SE compression during the late Paleogene to early Neogene, resulted in different trends and scales of structures such as folds, thrust faults, bedding shear zones, normal faults, dextral and sinistral strike- slip faults and shear fractures, faulted basins, cleavages and kinks, as well as late deflections of some structural trends. ② There were two stages of gold mineralization in the area during the late Silurian and late Triassic, both of which are related to contemporaneous granitic magmatic activity. ③ The main ore- bearing structures in the Yanlinsi gold field include three types: pre Mesozoic bedding brittle—ductile shear zones and interlayer faults, NW- to NWW- trending dextral strike- slip faults and shear fractures formed during Middle to Late Triassic, and internal and external contact zones of granite branches. The ore- passing structures of the late Silurian gold deposits were pre NE- trending deep thrust faults, while those of the late Triassic gold deposits were NE- trending thrust faults in the late Middle Triassic, NEE- and EW- trending thrust faults in the early Late Triassic. For the two stages of gold deposits, different types of faults formed during each deformation events after mineralization may become ore- breaking structures.
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JIANG Yongbiao, GUO Fusheng, LI Guangrong, LI Rong, LOU Fasheng, WANG Zhen, CHEN Liuqin, XI Haiman, YAN Luobin, LI Yichao, FAN Xiujun
2024,70(1):44-58, DOI: 10.16509/j.georeview.2023.10.025
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More than 30 red graben basins developed along some regional fault zones in Jiangxi Province from Late Cretaceous to Paleogene. These red basins with thick continental clastic sediments were the basis for the formation of Danxia landform. The evolutional stages of 228 sites of the Danxia landforms in Jiangxi Province were studied and show that: Most Danxia landforms sites locate in the northern and western piedmont of the Wuyi Mountains. Based on the satellite remote sensing and DEM data, the hypsometric integral simulation analysis of the Danxia landforms in this area is carried out. Evolutional stages of the Danxia landform are late mature to early old- age stage, and there is a tendency from south to north, shifting to higher evolution stage in the spatial distribution. Joints and the uplift of the Wuyi Mountains play an important role in the evolution of the Danxia Landforms in Jiangxi Province, which is shown as follows: ① the cliffs, thin strip of sky, lane valleys, stone walls, stone camp, peak clusters, peak forests and other landscapes developed in Longhu Mountain, Jiuxian Lake, Xianyan, Hamawu, Zhetingshan and Guifeng peak are all related to joints. ② Water erosion and other external forces play an important role in the stripping and leveling of Danxia landform. Statistics show that the closer to the Wuyi Mountains, the denser the peaks and the steeper the cliffs of Danxia landform, indicating that the uplift of the Wuyi Mountains is directly related to the development of the Danxia landform. In general, the red beds in Jiangxi Province provide the sediment source for the development of the Danxia landforms, and the uplift of the Wuyi Mountains controls the evolution stage of the Danxia landforms. It is worth noting that whether the joints in Danxia landform area is resulted from the uplift of the Wuyi Mountains needs to further study.
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ZHAI Wenjian, ZHANG Yong, TANG Guosheng, ZHAO Huan, ZHAI Wenfang
2024,70(1):59-82, DOI: 10.16509/j.georeview.2023.12.032
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The Baoshuping Formation of the Erlangping Group is an important Early Paleozoic sedimentary record in the North Qinling Mountains, but it has not been studied enough. This study aims to further determine its depositional age and tectonic environment through petrological, geochemical, and zircon U- Pb dating investigations of volcanic interbeds and granite veins within the Baoshuping Formation. The research results indicate that the lithology of the volcanic interbeds of the Baoshuping Formation in the Xiaguan Town, Neixiang County, western Henan Province, is biotite actinolite sodium schists, often interbedded with biotite quartz schists. The protolith of the rocks is andesitic tuff, characterized by relatively low SiO2 (52. 56%~62. 04%), relatively high Al2O3 (10. 70%~18. 55%), low MgO (4. 06%~6. 21%) and FeOT/MgO (1. 23~1. 81). It is enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs, Rb, Th, U, K), and relatively depleted in high field strength elements(HFSEs, Nb, Ta, P, Ti), exhibiting characteristics of magnesian andesite rocks. Based on geochemical characteristics and previous studies, it is inferred that the Baoshuping Formation may have formed in an active continental margin back- arc basin. The crystallization age of the protolith of biotite actinolite sodium schists obtained by U- Pb dating of zircon is 446. 0±1. 7 Ma, and the crystallization age of the intrusive granite porphyry is 430. 0±3. 0 Ma, accurately dating the formation age of the Baoshuping Formation as Late Ordovician to Early Silurian for the first time. Integrated regional research results suggest that the Xiaozhai Formation and Baoshuping Formation conform to the division scheme of the generalized Erlangping Group in terms of stratigraphic sequence and stratigraphic age. However, the Damiao Formation, Huoshenmiao Formation, and the composite of the Xiaozhai Formation and the Baoshuping Formation exhibit near- simultaneity in formation age and a nearly parallel spatial relationship, indicating that they are likely products of different depositional environments with roughly equivalent ages. In terms of tectonic attributes, it is believed that the Erlangping Group formed as a volcanic island arc due to the northward subduction of the Shangzhou—Danfeng Ocean before approximately 470 Ma, transformed into a back- arc basin between 470 Ma and 436 Ma, and completed the subduction closure process before approximately 430 Ma.
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2024,70(1):82-308, DOI:
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近期，根据国家标准化委员会、民政部印发的《团体标准管理规定》和《中国地质学会团体标准管理办法 (试行)》的有关要求，经中国地质学会团体标准委员会审定通过，批准发布《构造混杂岩带铁路工程地质安全评价规范》(T/GSC003-2023 )、《复杂艰险山区线状工程地质区划技术规程》(T/GSC 004-2023)、《超长距离工程地质勘察水平定向钻探规程》(T/GSC 005-2023)、《二氧化碳陆地封存工程选址指南》（T/GSC 006-2024）、《长大深埋铁路隧道智能化地质编录技术规程 》（T/GSC 007-2024）和《火山岩磁化率各向异性测量技术规范》（T/GSC 008-2024）6项团体标准。其中前3项标准自2023年12月29日起正式实施，后3项标准自2024年1月2日起正式实施。
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LI Yi, LI Zuochen, ZHAO Duanchang, ZHAO Pengbin, LV Junli, ZHANG Yafeng
2024,70(1):83-101, DOI: 10.16509/j.georeview.2023.09.085
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In the southern margin of North China Craton, a series of alkaline rocks of 1. 8 ~ 1. 6 Ga were found in Luonan, Shaanxi Province, and the west area of Henan Province. The study of these alkaline rocks can facilitate the understanding of the Paleoproterozoic tectonic environment of the southern margin of the North China Craton. Methods: This paper systematically studied the alkaline intrusive rocks in the Renjiatan—Qiaomaishan area in Luonan County, Shaanxi Province in terms of petrology, LA- ICP- MS zircon U- Pb dating, Lu—Hf isotope analysis, and petrogeochemistry, and discussed their genetic mechanism and tectonic setting. Results: The results show that the main lithology of the Renjiatan—Qiaomaishan pluton is syenite porphyry, with a weighted average age of 1689±20 Ma ( MSWD=0. 12 ), which indicates that the emplacement of the pluton happened in the Paleoproterozoic. The syenite porphyry is rich in alkali ( Na2O+K2O=7. 95% ~ 9. 5% ) and high in potassium ( K2O=4. 67% ~ 8. 51% ). The total amount of rare earth elements is high ( 496. 2×10-6 ~ 650. 2×10-6, average 543. 1×10-6 ), and the fractionation of light ( LREE=454×10-6 ~ 605×10-6 ) and heavy rare earth elements is obvious ( HREE=39. 3×10-6 ~ 45. 6×10-6 ). The light rare earth elements are relatively rich, while the heavy rare earth elements are deficient, and there is a weak negative europium anomaly. In addition, K, Rb, Ba, Th is rich, while Nb, Ta, P, Ti is deficient, and there is an obvious negative Sr anomaly. The value of εHf(t) is less than 0, the value of TDM1 is 2038 ~ 2218 Ma and TDM2 is 2250 ~ 2516 Ma, indicating that the materials in the magmatic source area are related to the enriched mantle or contaminated by the crustal materials. Conclusions: Therefore, the syenite porphyry in the Renjiatan—Qiaomaishan area is a melt formed by mixing the basaltic magma of the mantle with the medium—acid granitic magma formed by the Taihua complex TTG crust. It was formed in the tectonic environment of an intracontinental rift through strong crystallization differentiation, reflecting a response of the southern margin of the North China Craton to the cracking event of the Columbia Supercontinent.
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LU Zhishuai, XIE Qingbin, ZHANG Jinning, QI Liqi, XU Tao, CHEN Jia, XIANG Honghan
2024,70(1):102-122, DOI: 10.16509/j.georeview.2023.06.042
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The northern margin of Bogda Mountain is the key part between Junggar Basin and Tianshan Orogenic Belt, and is the key area to study the relationship between basin and mountain. The relationship between the tectonic evolution and sedimentary temporal and spatial evolution of the Middle and Late Permian in the northern margin of Bogda Mountain is controversial. Methods:By means of field survey, microscopic rock thin section identification, particle size analysis experiment and seismic data analysis, two sections of the eastern and western Bogda Mountain north margin, Dalongkou section and Jingjingzigou section, were studied to analyze their sedimentary types and evolution process, analyze the tectonic deformation and development characteristics of the basin—mountain, and explore the sedimentary response of tectonic movement. Results: The results show that the Guadalupian Wulabo Formation is lucustrine—delta facies, the Jingjingzigou Formation to the Hongyanchi Formation is lacustrine facies, the Lopingian Quanzijie Formation is alluvial fan—fluvial facies, and the Wutonggou Formation, the Guodikeng Formations are shoal shallow lucustrine—delta facies. The study area can be divided into two main structural layers, the lower structural layer with extensional fault depression as the main structure, and the upper structural layer with foreland thrust as the main structural deformation.Conclusions: Multi- stage tectonic activities controlled the sedimentary evolution of Guadalupian and Lopingian. Under the compressional tectonic background, the lacustrine facies of Guadalupian transformed into Lopingian alluvial fan—fluvial facies, and the tectonic activities tended to be stable in the late period, and the region entered the peneplanization stage.
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ZHAO Junwei, CHEN Gongyang, ZHANG Ling, YANG Yintao, SONG Xinxin, WANG Heng
2024,70(1):123-136, DOI: 10.16509/j.georeview.2023.07.011
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The 2nd Member of Xujiahe Formation in Xinchang area of western Sichuan is rich in natural gas resources, with large area of sandbody, low reservoir porosity and permeability, and complex genesis of sweet spot. It is of great significance to clarify the type and genesis of sweet spot in the 2nd Member of Xujiahe Formation in Xinchang area. Methods: Based on the analysis of reservoir petrology, pore throat characteristics and effective fracture characteristics, sweet spot is classified by core observation, thin section analysis, micro CT, cathodoluminescence and other technical means. Results: There are three types of sweet spot in the 2nd Member of Xujiahe Formation in Xinchang, including matrix pore type, fracture type and bedding fracture type. The causes of different types of sweet spot are different. High- energy distributary channels are formed under strong hydrodynamic conditions, quartz- rich sandstones are the basis for matrix- type sweet spot formation, and matrix- type are easily formed under relatively weak compaction, cementation and strong dissolution. It is easy to develop fracture- type in the matrix with good porosity and permeability near large faults. The distribution scale of bedding fracture type is small, there are differences in particle size and composition at different types of bedding interfaces, resulting in differential diagenesis process, forming a mechanical weak surface. Conclusions: The development of sweet spot is controlled by sedimentation, diagenesis and structural heterogeneity in the Tx2 Member in Xinchang area. The genetic analysis of sweet spot type is conducive to the classification and evaluation of it.
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GUO Kexin, LIU Yongshun, NIE Baofeng, GUO Lei, ZHANG Hui, HUANG Zhicong, HOU Peng, LI Yao
2024,70(1):137-154, DOI: 10.16509/j.georeview.2023.08.085
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Volcanic field in Jingpo Lake area is an important window for the study of intra- continental Cenozoic basalts. Previous studies on the Xingshan Volcano Group located in the southeast of this area have rarely been conducted and the possibility of magma assimilation and mixing in this area has been denied. The basalts of the Xingshan Volcano Group have been systematically studied in terms of petrology, petrochemistry and Sr—Nd—Pb isotopes. It is believed that the basalts of the Xingshan Volcano Group are mainly basanites and trachy- basalts. The fractionation of olivine and clinopyroxene occurred during the ascent of the primary magma, and the assimilation and mixing occurred in the upper crust, with weak AFC effect. The comparison between the basalts of the Xingshan Volcano Group and the Jingbohu basalts during the same eruption shows that the basalts in both areas are derived from the partial melting of garnet peridotite, and the partial melting degree of the Xingshan Volcano Group is slightly lower than that of Jingbohu basalts. In terms of magmatic source region, the Xingshan Volcano Group is the mixing source of PREMA and BSE end- member. The heterogeneity of magma source area and the assimilation and mixing during magma evolution are the main influencing factors that cause the difference between the lithologic features of the Xingshan Volcano Group and Jingpohu Volcano Group.
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LI Qiang, CHENG Xueqin, WANG Yankai, LI Zhimin, LIU Hongzhang, YANG Ning, SHEN Jinqing, LUO Shanxia
2024,70(1):155-174, DOI: 10.16509/j.georeview.2023.08.035
Abstract:
This paper provided petrographic, zircon U- Pb age and geochemical characteristics of intermediate—basic complex in the upper reaches of Pangu River in the northern Great Hinggan Mountains. The formation age, genesis and geological implications are discussed.Methods:Based on the field work, through the microscopic observation, the whole rock chemical analysis of different rock types and the LA- ICP- MS zircon U- Pb isotopic chronology of hornblende gabbro.Results: The rock types of the composite pluton are mainly hornblende gabbro and gabbro, rare quartz diorite, diorite, pyroxenite, olivine gabbro and other intermediate rocks or ultrabasic rocks. The dating results show that the formation age of the hornblende gabbro is 479. 2±2. 1 Ma, formed in the Early Ordovician. The intermediate—basic composite pluton in the upper reaches of the Pangu River have SiO2 contents ranging from 40. 74% to 54. 95%, Fe2O3T contents ranging from 3. 99% to 14. 66%, MgO contents ranging from 3. 36% to 17. 78%, Mg# values ranging from 47 to 79, which are (high potassium) calc- alkaline series rocks, relatively enriched in light rare earth elements and depleted in heavy rare earth elements with δEu from 0. 77 to 2. 06. They are relatively enriched in large ion lithophile and radioactive elements such as Rb, Ba, U, K, Pb and Sr, and depleted in high field strength elements such as Nb, Ta and Ti, which is similar to the geochemical characteristics of arc magmatic rocks in subduction zone.Conclusions: The magma was originated from partial melting of mantle dominated by subduction fluid metasomatism supplemented by sediment melt metasomatism. The source area is dominated by spinel bearing garnet lherzolite, and a small amount of spinel lherzolite, which experienced different degrees of crystallization differentiation in the rising process. Comprehensive analysis shows that the Early Paleozoic intermediate—basic complex in the upper reaches of Pangu River was formed in the tectonic environment of continental extensional zone (or initial rift), which is probably related to the lithosphere extension background after the collision between the Siberian plate and the Erguna massif.
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LI Wei, TANG Juxing, LU Jie, GUO Na, YUAN Huixiang, LIAN Dunmei
2024,70(1):175-188, DOI: 10.16509/j.georeview.2023.07.035
Abstract:
Tieshanlong tungsten ore field is located in the eastern section of Nanling W—Sn—polymetallic metallogenic belt, which have produced more than 100 kt of wolframite around the Tieshanlong granitic complex. There have three kinds of granites: the early coarse- grained porphyritic biotite granite, the complement fine grained muscovite granite and latest granite porphyry veins, showing common geochemical characteristics of peraluminous, high- K and calc- alkali category, integrated with enrichments of SiO2, Al2O3, K2O, W, Sn, Cu, Mo, depletions of Ba, Sr, Ti, P, REE and Eu negative anomaly. The REE distribution curve shows a typical “seagull” distribution with M- type tetrad effect. LA- ICP- MS zircon U- Pb dating of granite porphyry yields emplacement age of 146. 7±0. 5 Ma (MSDW=0. 5), with n(176Lu)/n(177Hf) and fLu/Hf rations of 0. 000 973～0. 001 989 and -0. 97～-0. 94, respectively. The εHf(t) values range from -17. 9 to -10. 3, and TDM2 are 1. 86 Ga to 2. 33 Ga, indicating primary reworking of the Paleoproterozoic crustal material. The comprehensive analysis shows that Tieshanlong ore field have three stages magmatic activities of 170～155 Ma, 155～150 Ma and 150～145 Ma, and the W—Sn mineralization is mainly occurred in the second stage. Granite porphyry is rich in Cu, Mo and W, which is closely related to the Cu—W—polymetallic mineralization, and show a great prospecting potential in the deep part of Tongling deposit.
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ZHENG Wei, CHEN Tianhu, DU Jianguo, CHEN Fang, DING Ning, ZHANG Shu
2024,70(1):189-206, DOI: 10.16509/j.georeview.2023.09.075
Abstract:
The Fuling pluton is a granitic body located in the adjacent area of Anhui and Zhejiang provinces, in the eastern section of the Jiangnan Orogenic Belt. The magmatic rocks are distributed along the Ningguo—Jixi deep fault extending near the NE direction. The research work on the Yulongchuan(γ53 -2) unit granite in Fuling pluton has been carried out in this paper. Methods: Based on the field work, we finished microscope observation, whole- rock geochemical analysis, LA- ICP- MS zircon U- Pb dating and in situ Lu—Hf isotope geochemistry for the Yulongchuan (γ53 -2) unit granite. Results: The LA- ICP- MS zircon U- Pb dating shows that the emplaced age of the granite is 131. 8±0. 9 Ma, which is the product of magmatic activity in the late stage of the Jiangnan Orogenic Belt. The pluton is rich in silica and alkali, and poor in calcium and iron. The characteristics of trace elements show that there are higher Rb, Th, U, Ga, Zr and Y contents, and there are lower Sr, Ba and Nb. The rare earth element pattern curve presents a typical "seagull" distribution, showing strong negative Eu anomalies. Negative anomalies of Ba, Sr and Nb are found in the primitive normalized mantle spider map of trace elements. The zircon εHf (t) of Fuling granite varies from -7. 0 to -4. 6, and the two- stage model age (TDM2) ranges from 1478 to 1630 Ma. Conclusions: The high SiO2 content, Rb/Sr value and low Ba and Sr content show that the Fuling granite has the typical characteristics of the A- type granite in the eastern part of Jiangnan Orogenic Belt, southern Anhui Province. The Fuling pluton has the characteristics of homologous magmatic evolution, and the separation and crystallization of apatite and ilmenite minerals may exist in the source area, while the separation of pyroxene minerals is less. The source rocks of Fuling pluton are mainly derived from partial melting of mafic rocks in the crust, and their geochemical characteristics are inherited from the source rocks. The Fuling granite may have been formed by partial melting of the ancient lower crust in Mesoproterozoic, and its source material is mainly the ancient lower crust. The formation of Fuling pluton may be influenced by collision. The Fuling pluton was formed in post- collision. The Mesoproterozoic basement rocks were melted on a large scale, resulting in the formation of Fuling A- type granite.
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ZHANG Jianchao, ZHU Kongyang, YANG Bo, SU Meixia, XU Liquan, ZHOU Fei, DONG Chuanwan, SHEN Zhongyue, WU Yanjun, MENG Xiaoling, SHE Linlin
2024,70(1):207-227, DOI: 10.16509/j. georeview. 2023.09.033
Abstract:
The Biqigenao granitic complex in northeastern Darhan—Maoming’an Union Banner (Damao Banner) is composed of two phases of intrusions, the lithology of which is granodiorite and monzogranite, the former being the main lithology of the granitic complex. Granodiorite is mainly composed of plagioclase (An= 14~30), quartz, alkali feldspar and amphibole, with mafic microgranular enclave inside; The monzogranite is mainly composed of quartz, alkali feldspar and plagioclase (An= 12~23). Zircon U- Pb dating shows that the granitic complex was formed in the Late Permian, and its formation age is 259 Ma. The main granodiorite with SiO2 = 66. 37%~68. 70% is aluminous—weakly peraluminous (A / CNK = 0. 99~1. 01), which is characterized by enrichment of light rare earth and large ion lithophile elements, depletion of heavy rare earth and high field strength elements, belongs to I- type granite; mafic microgranular enclave is rounded or elongated flat lenticular, and the age is consistent with the granodiorite, which is the product of magma mixing; Monzogranite is high silica granite (SiO2= 71. 51%~73. 09%), alkali- rich (Na2O + K2O = 7. 91%~8. 61%) and weakly peraluminous to strongly peraluminous (A / CNK=1. 07~1. 11), is a differentiated I- type granite. The εHf (t) of Ziron distribution range is -3. 0~3. 4, and the corresponding Hf isotope two- stage model age is 1473~1057 Ma. It has relatively low (87Sr/86Sr) i value (0. 704829~0. 705327), ε Nd (t) value is -5. 85~-8. 86, and the corresponding Nd two- stage model age is 1. 69~1. 45 Ga. Based on the regional research data, it is considered that the Biqigenao granitic complex is formed by mixing the depleted mantle component with the partially melted ancient crustal material induced by it, and belongs to the post- collisional granite.
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HAN Jianguang, WANG Qing, XU Yuan, LIU Zhiwei
2024,70(1):228-238, DOI: 10.16509/j.georeview.2023.08.011
Abstract:
Seismic data noise suppression method based on deep learning is an important field of seismic data denoising processing. Deep learning method breaks through the limitation of traditional filter processing, and shows high efficiency and good signal- to- noise separation effect in noise suppression of conventional seismic data. However, for deep weak reflection data, the current deep learning methods have limited feature extraction ability, and it is difficult to achieve good denoising effect. Combined with the characteristics of deep reflection seismic data, and aiming at the limitations of current deep learning noise suppression methods in feature extraction and data set dependence, we propose a stochastic noise suppression method for deep reflection seismic data based on Attention Cycle- Consistent Generative Adversarial Networks (A- CGAN). Using the domain mapping idea of Cycle- Consistent Generative Adversarial Networks (Cycle- GAN), the requirements on data sets are reduced. In order to build a denoising network suitable for deep reflection seismic data, improvements are made to Cycle- GAN from three aspects: adding residual structure and attention mechanism to Cycle- GAN generator (denoising device) to deepen the depth of the network and improve its feature extraction capability; the block decision is used in the discriminator of Cycle- GAN to improve the precision and accuracy of the discriminator; adding the perception consistency loss function to the loss function improves the ability of the network model to recover texture details. The numerical model data and the actual deep reflection seismic data are tested to verify the effectiveness of the optimization algorithm, which shows good application value.
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MEI Jiacheng, LIU Lei, YIN Chuntao, ZHANG Qunjia, WANG Le
2024,70(1):239-250, DOI: 10.16509/j.georeview.2023.08.031
Abstract:
Geological mapping is a basic work for geology. However, the working areas for geological mapping are mostly mountainous areas with high elevation and steep terrain which is difficult for field work. It’s urgent to develop a semi- automatic to automatic lithologic mapping method using remote sensing data by combining the spectral features and spatial features of each lithologic unit. Therefore, this study, taking Baixiani Mountain, Beishan Mountains, Gansu Province, as the working area, utilized two machine learning methods to test the feasibility for automatically lithologic mapping. Methods:Two methods, support vector machine and extreme learning machine, combined with a spatial feature extraction method, quick shift algorithm, were used to process ASTER remote sensing data for lithologic classification. Results:The overall accuracy of support vector machine classification was 89.17%, while the extreme learning machine not only had the advantage of requiring fewer adjustable parameters, but also had higher classification accuracy and speed than the support vector machine, with an overall accuracy of 96.70%. The use of image spatial features extracted by the quick shift algorithm effectively reduced misclassification areas and improved lithological classification.Conclusions:The study confirmed that the lithological classification method combining extreme learning machine based on spectral features and quick shift algorithm based on spatial features has advantages such as objectivity, efficiency, and high accuracy, and can provide reliable data support for subsequent geological mapping and mineral exploration work, with high promotion value in the field of remote sensing lithological classification.
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2024,70(1):250-250, DOI:
Abstract:
依据文献计量学的原理和方法，经研究人员对相关文献的检索、统计和分析，以及学科专家评审，中国地质学会主办、合办、协办期刊《地质学报》《地质论评》《矿床地质》《岩石矿物学杂志》《岩矿测试》《西北地质》《沉积学报》《石油与天然气地质》《地质与勘探》《石油实验地质》10本中文刊物入编2023年版《中文核心期刊要目总览》（即第10版）之 “地质学”类的核心期刊。
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WANG Yingfa, QU Yaming, MOU Ru, ZHAO Xin, XU Hanhua, WU Zhonghai
2024,70(1):251-261, DOI: 10.16509/j.georeview.2023.08.041
Abstract:
The long extension of the Xiaojiang fault and its staggered distribution of secondary faults make it difficult for major projects in the region to avoid the impact of active fault zones, therefore, the activity of active faults and site stability are the main engineering stability problems faced by regional major engineering construction. It is of great significance for engineering geological research and disaster prevention and reduction. Methods: In order to find out the effect of active fault on the highway engineering site, based on the geological and tectonic background of the Xiaojiang fault, this paper makes full use of the existing research results, focuses on the regional tectonic environment and fault characteristics, calculates and analyzes the activity rate of the eastern branch of the Xiaojiang fault and determines the degree of fault activity through geological mapping, physical exploration and combined with chronological testing;Taking into account factors such as fault activity, seismic intensity, and rock mass characteristics, the stability of the regional site has been graded. Results: The results show that the average horizontal displacement rate of the Xiaojiang fault is 66 mm/a, which is considered as a strong active fault and the stability of the regional engineering site is divided into extremely unstable regions. Conclusions:It is concluded that the impact on the project was most serious in the 10 km area on both sides of the highly active fault, which provides theoretical and data support for site selection and seismic design of highway engineering.
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LI Zhen, XU Guanli, LIU Rong, SHI Kaiwen
2024,70(1):262-276, DOI: 10.16509/j.georeview.2023.08.055
Abstract:
Basalt fiber is a kind of high-performance fiber manufactured by melting and drawing from basalt or rocks of similar composition. Fluctuation in the composition of natural rocks can cause difficulties in drawing and instability of fiber properties. This paper collected data on the chemical composition of 54 groups of raw rock and 114 groups of basalt fiber samples. The petrological, parameter index and other characteristics of the raw material needed for basalt fiber were summarized, and the optimal ranges of related parameter indexes of raw materials were proposed. The characteristics of raw rock which is suitable for the production of basalt fiber can be summarized as follows: from the perspective of petrology, basic rock or intermediate rock with a SiO2 content of 53% to 57% is the optimal; the most suitable rock type is basalt or andesite; the most appropriate rock texture is intersertal texture, vitrophyric texture or hyaline texture. The influence of structure is indirect, mainly due to some adverse minerals that may be contained in fumarolic structure or amygdaloidal structure. From the perspective of mineral composition, hydrous minerals such as serpentine and zeolite will cause bubbles in the melt, which will affect the continuity of fiber preparation but will be conducive to the full melting of raw materials. High melting point minerals such as forsterite and magnetite will make it difficult for raw materials to melt completely, resulting in uneven melting and easy crystallization. From the perspective of parameter index, the optimal range of acidity coefficient (Mk) is 4. 0 to 5. 5. The viscosity coefficient (Mv) is 2. 0 to 3. 0. The ratio of silicon aluminum oxides to other oxides is 1. 5~3. 0. The molar fractions of oxides are n(RO) = 20% to 30%, n(RO2) = 57% to 70%, and n(R2O3) = 10% to 16% (R stands for cations).
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2024,70(1):277-286, DOI: 10.16509/j.georeview.2023.07.012
Abstract:
This paper intends to analyze the spatial distribution characteristics of geological culture villages (towns) and their influencing factors from a geospatial perspective, in order to provide reference for the scientific layout and sustainable development of geological culture villages (towns) in China. Methods: the spatial distribution characteristics of 50 geological culture villages (towns) in China and their influencing factors are studied by using the methods of the nearest neighbor index, unbalanced index, kernel density analysis method and Geodetector. Result and Conclusions: The study shows that: ① The spatial distribution of geological culture villages (towns) is random; ② The number of geological culture villages (towns) in each province (city and district) varies significantly, with uneven spatial distribution and a pattern of "more in the east and less in the west"; ③ The geological culture villages (towns) form one high- density core area, two secondary high- density gathering areas and one core extension zone; ④ The factors affecting the spatial distribution of geological culture villages (towns) in China are composed of three primary indicators: characteristic geological resources, natural conditions and socio- economic and human resources. The factors affecting the spatial distribution of geological culture villages (towns) in China are composed of three primary indicators, namely geological resources, natural conditions and socio- economic and human resources, among which socio- economic and human resources have the greatest influence on the spatial distribution of geological culture villages (towns) and have significant effects. In the evaluation and construction of geological culture villages (towns) in the future, the construction and declaration of geological culture villages (towns) in the central and western regions should be strengthened; the evaluation of geological culture villages (towns) in the central and western regions should be appropriately tilted; the publicity of geological culture villages (towns) should be increased; the geological characteristics and folk culture should be fully explored, and the integration of geological culture villages (towns) and culture should be strengthened.
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SU Zhandong, WANG Zhiwen, SUN Jinzhong, ZHANG Jianyong, LIANG Jinping, NIU Yao, ZHANG Zhitai, ZENG Yangnong, LI Mengyuan
2024,70(1):287-308, DOI: 10.16509/j.georeview.2023.09.001
Abstract:
As a convenient, efficient and low-cost research method, geomechanical model experiments can not only present the failure process of engineering intuitively, but also serve as an important research means to understand the overall mechanical characteristics, failure mode and stability of engineering. Therefore, geomechanical model experiments are widely used in the study of various geotechnical engineering problems. Due to the low deformation modulus of geomechanical model materials and their extremely sensitive strain under the same stress conditions, deformation measurement is crucial in model experiments. In order to improve the convenience and accuracy of deformation measurement in geomechanical model experiments, the main methods of deformation measurement in the current geomechanical model are summarized and analyzed. The results indicate that currently, the methods for measuring model deformation mainly include electrical measurement methods, optical measurement methods, and mechanical measurement methods. Among them, electrical measurement methods mainly includes resistance strain gauge methods and displacement meter method, optical measurement method mainly includes fiber optic sensor method, digital image correlation method, photoelastic patch method, and moire interferometry method, and mechanical measurement methods mainly includes dial gauge measurement method and theodolite observation method, through the explanation and comparison of the working principle, main application cases and advantages and disadvantages of various methods. The main difference between the different methods is the difference in the measurement range and the scope of application, among which the percentile meter methods is suitable for measuring the deformation of a small area. To measure the internal deformation, the resistive strain gauge method and fiber optical sensor method can be selected. For deformation in larger areas, the displacement meter method and the optical fiber sensor method can be selected. The theodolite observation method can be selected for the specified point displacement; For full-field observation, digital image correlation method, moire interferometry and photoelastic patch method can be selected. This achievement can provide an experimental reference for the experimental deformation measurement of related geomechanical models.
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GUO Zeqing, ZHAO Wenzhi, XIE Zengye, WANG Zhihong, JIANG Hua, LI Jian, ZHU Guangyou
2024,70(1):309-329, DOI: 10.16509/j.georeview.2023.09.031
Abstract:
The Sinian—Cambrian natural gas resources are abundant in Sichuan basin. In recent years, two giant gas- accumulating areas with two trillion cubic meters reserves have been discovered in the central Sichuan palaeo- uplift and northern slope areas of the Sichuan Basin. In order to clarify the scale of natural gas resources and future exploration directions in this field, and to create a practical and feasible evaluation method for crude oil cracking gas resources, this study was conducted. Methods: Based on the basic understanding that the natural gas in this area came from the cracking of crude oil in ancient oil reservoirs, the resource amount of crude oil cracking gas was calculated according to the technical route of kerogen generating oil and then cracking gas from ancient oil reservoirs. The formation thickness maps, lithofacies palaeogeography maps, comprehensive evaluation maps of hydrocarbon source rock, erosion thickness maps and oil generation dynamics parameter plates were inputted to PetroMod 3D basin simulation software, and the 3D geological model was established to calculate oil generation in five primary tectonic units, Then, the oil migration and accumulation coefficient, oil cracking rate, gas loss rate and the partition coefficient of Cambrian oil migration were discussed, and the calculation formula of natural gas loss coefficient was established, eventually the conventional natural gas resources of the Sinian and Cambrian were obtained. Results: The oil generation history of the basin and five primary tectonic units has been restored, and the critical moment of the formation of ancient oil reservoirs has been clarified. The conventional natural gas resources of the Sinian Cambrian in the entire basin and five primary tectonic units have been obtained. Conclusions: In Sichuan Basin, oil generation quantity of the Cambrian was 1. 05 × 1012 t, with 0. 33 × 1012 t for the Sinian. From the perspective of the whole basin, there is a small amount of oil generation in Ordovician, and a large amount of hydrocarbon generation has started since Silurian, of which Permian Triassic is the main oil generation period. Since Cretaceous, Source rock has entered a high maturity period, oil generation has stopped, and ancient oil reservoirs began to crack. The ancient oil reservoir was formed during Triassic Early and Jurassic, and the key moment for the formation of the ancient oil reservoir is the end of Triassic. The conventional natural gas resources of the Sinian and Cambrian in the whole basin are 13. 43 trillion cubic meters, including 5. 43 trillion cubic meters in Cambrian and 8. 0 trillion cubic meters in Sinian. Apart from central Sichuan, southern and eastern Sichuan have great exploration potential, especially the platform margin zone and intra- platform granular beach located on both sides of Deyang—Anyue rift in southern Sichuan are the practical areas for further exploration.
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FENG Huaiwei, XU Shumei, WANG Jinduo, ZHANG Guanlong, ZENG Zhiping, REN Xincheng, XIU Jinlei, WANG Qianjun
2024,70(1):330-345, DOI: 10.16509/j.georeview.2023.08.021
Abstract:
Based on the data from cores, logs, and drilling, and combined with previous data on apatite and zircon ages at the periphery of the Junggar Basin, this paper presents a systematic study of the relationship between the provenance directions, provenance types, sedimentary system spreading, sand configuration, and reservoir properties of the 2nd member of Jurassic Sangonghe Formation based on the basic principles and methods of sedimentology, stratigraphic stratigraphy, sedimentary basin analysis, and reservoir sedimentology, The study shows that the braided river regressive sedimentary sequence was formed under the tectonic background of rapid uplift/slow subsidence, and in the five- level stratigraphic framework, the strongly scoured superimposed sand bodies of the river channel are found in the 1st and 2nd sandbody assemblages, with delta regression and strong scouring of branch channels, resulting in superimposed sand bodies of the river channel, with a single microfacies type, single sand body thickness thinning upward, stable distribution of sand bodies in the whole area, and good reservoir properties. Weakly scoured superimposed sand bodies are found in the 3rd and 5th sandbody assemblage where the delta is receding and the branch channels are not obviously scoured, forming a "binary structure" of the river, with single sand body thickness thinning upward, fine grain size and good reservoir properties; the combined sand body of the river dam is found in the 4th sandbody assemblage, where a mouth bar is formed at the end of the submerged diversion channel in the process of delta receding. In conclusion, under the background of shallow water, low accommodation space, rapid uplift- slow curtain settlement tectonics, the direction, proximity and type of the source of shallow water delta are the key factors affecting the distribution of sedimentary micro- phase, and also affecting the sand body configuration and its reservoir properties and material basis.
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WANG Shuai, ZHAO Dongfang, LI Yingjie, JIN Song, DONG Peipei, ZHANG Xiawei, MENG Du
2024,70(1):346-362, DOI: 10.16509/j.georeview.2023.08.001
Abstract:
Lying along the eastern Hegenshan suture zone in Horqin Right Middle Banner of Inner Mongolia, the Jurihe A2- type monzogranite intruded into Early Carboniferous Duerji tectonic melange belt. Based on systematic field geological characteristics, petrology, geochemistry, zircon U- Pb chronology of it, the purpose of study is to determine genetic type of pluton, tectonic setting, and provide evidence for the closure time of Hegenshan Ocean, a branch of the Paleo- Asian Ocean. The Jurihe monzogranite is mainly composed of fine- grained and medium- grained monzogranite. LA- ICP- MS zircon U- Pb dating shows that the age of granite is 203. 7±1. 6 Ma, indicating that formation age is Late Triassic. The granite is geochemically characterized by high SiO2(71. 08%~76. 62%) and alkali (Na2O+K2O=7. 99%~9. 28%), but low CaO (0. 25%~1. 67%) and MgO (0. 05%~0. 63%). The obvious negative Eu anomaly (Eu=0. 14~0. 50), relative enrichment of Rb, Th, U, K and Ga, depletion of Ba, Sr, P and Ti, as well as high 10000Ga/Al (3. 62~4. 90), TFeO/MgO (3. 40~14. 80), (Na2O+K2O)/CaO (5. 03~31. 96) values show characteristics of A2- type granite, representing that it was formed in post- orogenic extensional environment. At the same time, combining with the temperature and pressure conditions of magma origin, it is believed that the pluton may be caused by partial melting of crustal hornblende rocks containing plagioclase under the condition of dehydration and subsequent crystallization differentiation in post- orogenic stage. Combined with the spatio—temporal evolution of Early Carboniferous—Late Triassic ophiolites, intra oceanic arcs and post- collisional granitoids in the eastern part of Central Asia Orogenic Belt, suggesting that the Hegenshan Ocean was probably closed at the end- Permian and entered post- orogenic extension stage in Triassic.Methods：Based on field geological surveying, petrology, geochemistry and LA- ICP- MS zircon U- Pb geochronology of the Jurihe monzogranite, this paper discusses the petrogenesis and tectonic setting of the monzogranite, and the final closure time and subduction process of the Hegenshan Ocean.Results(1) The Jurihe monzogranite was intruded into the Early Carboniferous Duerji tectonic melange belt in the Horqin Right Middle Banner. The LA- ICP- MS zircon U- Pb age is 203. 7±1. 6 Ma, indicating that its emplacement occurred during the Late Triassic.(2) The Jurihe monzogranite is characterized by high SiO2, rich alkali, and poor CaO and MgO, with A/CNK=0. 93~1. 14 and A/NK=1. 09~1. 26. The negative Eu anomaly is significant, and Rb, Th, U, K, and Ga elements are relatively enriched, while Ba, Sr, P, and Ti elements are relatively depleted. Additionally, the 10000Ga/Al, TFeO/MgO, (Na2O+K2O)/CaO values are high, indicating a metaluminous-weakly peraluminous A2- type granite.(3) The Jurihe monzogranite is the product of extension after closure of the eastern Hegenshan suture zone, which provides petrological evidence for the Hegenshan Ocean closing at end- Permian and entering post- orogenic extension stage in Triassic. Partial melting and subsequent crystallization differentiation of shallow crustal materials under low- pressure and high- temperature may be its genesis, which records information on the evolution of post- orogenic plate break- off and mantle derived basaltic magma underplating in the eastern Hegenshan suture zone during Late Triassic.Conclusions:This study determines the Late Triassic (203. 7±1. 6 Ma) Jurihe monzogranite, which was probably formed in post- orogenic extension setting and is the A2- type granite. The Jurihe A2- type monzogranite might have been derived from underplating of mantle derived basaltic magma caused by the separation of previously subducted plate fragments in the shallow low- pressure environment and subsequent crystallization differentiation. The discovery and confirmation of the Jurihe A2- type monzogranite in the Late Triassic provide new evidence for Hegenshan Ocean closure and subsequent post- orogenic extension setting.
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ZHANG Zhiwei, LIU Wenqing, YUAN Ye, GAO Jianwei, SU Guifen
2024,70(1):362-366, DOI: 10.16509/j.georeview.2023.08.065
Abstract:
Popularizing of core science and technology resources is an important way to open up the chain of geological research and popularization of science. By combing the current situation of core science and technology resources in China, this paper analyzes the practical significance of core science and technology resources popularization, focusing on the exploration and practice of core science and technology resources in five aspects of geological popularization, and puts forward five suggestions for the future popularization of core science and technology resources, such as establishing a good policy mechanism system, changing the concept of researchers, transforming scientific knowledge into popularization, applying new technologies and means, and summarizing the implementation of popular science activities.
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YUAN Dingcheng, ZHANG Yongli, LAI Guanming, GONG Enpu, WANG Junjie, LI Depeng
2024,70(1):367-382, DOI: 10.16509/j.georeview.2023.09.022
Abstract:
The stromatolites in Ganjingzi Formation, Sinian System (Ediacaaran System), in Liaodong Penisula, are ideal object for studying the construction of Neoproterozoic microbial carbonate, which is of great significance for restoring paleoenvironment and paleoecology.Methods: Based on field investigation on the Yuanjiagou profile, Fuzhou Bay, Liaodong Penisula, the position of the outlying stromatolites in the Ganjingzi Formation, the macroscopic morphological characteristics of stromatolites, and the morphological changes of stromatolite columns and lamellar structures are identified and recorded. Through the observation of the laminae, the different growth stages of the laminae are distinguished, and the influence of the environment on the bifurcation and morphology of the stromatolite columns are analyzed. The stromatolites building process and characteristics of Neoproterozoic the Ganjingzi Formation stromatolites are reconstructed by comparing them with modern stromatolites. After comprehensive discussion, the growth mechanism of the Ganjingzi Formation stromatolites is summarized.Results:Based on different lithology, the Ganjingzi Formation is divided into three sections from bottom to top in the Yuanjiagou profile, Fuzhou Bay, Liaodong Penisula. Stromatolites appear at the bottom of the Lower Member and the top of the Upper Member of the Ganjingzi Formation. The stromatolites at the bottom produce stromatolite mound or the large- scale stromatolite biostrome at the top. The stromatolites colonize the hard substrate and grow perpendicular to the substrate at the beginning stage. Under the influence of hydrodynamic conditions and photosynthesis, stromatolites gradually grow vertically upward. The stromatolites in the stromatolite mound present a pattern combination of corrugate—columnar—cumulus, and the stromatolites in the stromatolite biostrome present a pattern combination of corrugate—columnar—long columnar, both of which reflect the changing trend of stromatolite morphology with increasing water depth. A comprehensive comparison of modern stromatolites shows that the microstructure of the Ganjingzi Formation stromatolites is similar to that of modern stromatolites, and growth and branch have certain comparability.Conclusions: The stromatolite laminae of the Ganjingzi Formation show different sequences of formation of light laminae and dark laminae. The morphological characteristics of stromatolites show that the growth and branched of stromatolites are affected by the environment to some extent. The formation of stromatolites is subject to environmental changes. The extensive growth of stromatolites requires ample space and a suitable environment. The presence of hard substrates creates favorable conditions for the growth of stromatolites. From micro to macro, the influence of biological factors on the growth and building characteristics of microbial mats gradually increased, while the influence of environmental factors gradually decreased.
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LV Zhaoying, XUE Guicheng, HE Yusheng, LIN Yihua, WEI Changxin, HU Zailong, YUAN Qinmin, LV Changyan, HUANG Wuxuan, WANG Chao, ZHANG Zhizhuang, LIN Di, CHANG Zhenyu
2024,70(1):383-398, DOI: 10.16509/j.georeview.2023.08.002
Abstract:
The geoheritage resources in Hainan Tropical Rainforest National Park are extremely important components of the natural resources and natural environment in the tropical rainforest. The geological environment of the geoheritage is fundamental to the biodiversity of the tropical rainforest. The scientific protection and rational utilization of geoheritage resources is one of the important contents of the construction of Hainan Tropical Rainforest National Park. It is important to provide basic information and ideas for the protection and utilization of geoheritage resources in the National Park. Methods: Based on the comprehensive and systematic investigation and evaluation of geoheritage resources in Hainan Tropical Rainforest National Park, according to the ‘specification for geoheritage investigation （DZ/T 0303- 2017）’, this paper systematically summarizes the characteristics and distribution of important geoheritage resources in Hainan Tropical Rainforest National Park, and conducts a qualitative and quantitative comprehensive evaluation and classification of their scientific and aesthetic values. Results:The research results show that there are various types of geoheritage in Hainan Tropical Rainforest National Park, with the main categories being fundamental geology and geomorphological landscape, including 4 categories: important fossil production area, important fossil origin category, rock and soil geomorphology, water geomorphology and volcanic geomorphology, and 6 subclasses: Paleobiota Fossil Site, Carbonate Rock Landform, Intrusive Rock Landform, Detrital Rock Landform, Waterfall, and Volcanic Rock Landform, with a total of 21 important geoheritage sites. Conclusions: Through the evaluation of geoheritage sites in Hainan Tropical Rainforest National Geopark, there are 1 world- level geoheritage site, 17 provincial- level geoheritage sites, and 3 sub- provincial- level geoheritage sites in Hainan Tropical Rainforest National Park. We suggest incorporating the protection of geological relics into the National Park protection planning system, and the utilization of geoheritage sites should be be integrated with the reality of the National Park.
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2024,70(1):399-403, DOI: 10.16509/j.georeview.2023.08.095
Abstract:
This article briefly reviews the process of the establishment of Geological Society of China, analyzes the role of young people in the background of the establishment of the Society, and sorts out the importance that the Society has attached to the work of young members in terms of system, award setting, organizational construction, and academic activities over the past century. It also proposes to inherit excellent traditions, strengthen the confidence of geological culture, enrich and explore new service methods, and unite the vast number of geological young people to play the role of young members in Society’s service to geological science and economic social development.
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2024,70(1):403-404, DOI:
Abstract:
为服务生态文明建设和乡村振兴，支撑自然资源和地质调查工作发展，普及地球科学知识，科学、规范、有序推进全国地质文化村（镇）建设管理，中国地质学会对《地质文化村（镇）评定授牌和监督管理办法》（附件）进行了修订。新修订的办法已经中国地质学会第40届理事会第55次常务理事会议（通讯）审议通过，现予以印发，请遵照执行。
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2024,70(1):2024010000-2024010000, DOI:
Abstract:
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DENG Yuwei, YIN Senlin, LI Bingke, NIE Xin
2024,70(1):2024010001-2024010001, DOI: 10.16509/j.georeview.2024.01.011
Abstract:
The microscopic pore structure of a tight sandstone reservoir is highly intricate, presenting challenges in its quantification. The primary focus was on utilizing digital core technology to analyze representative samples extracted from Member 8 of the Lower Permian Shihezi Formation at the TianShengQiao braided river outcrop in Fugu County, Yulin City, Shanxi Province.Methods: To achieve the research objectives, eight typical samples were meticulously selected and underwent a series of processes, including image filtering, threshold segmentation, and the maximum sphere equivalent algorithm. Digital representations of the core samples were then processed to establish both three- dimensional pore structure models and sphere—stick models. Microscopic structural parameters were calculated to quantitatively characterize the size distribution and connectivity features of pores and throats in tight sandstone reservoirs. The study also incorporated geological assessment methods to complement the quantitative evaluation of the micro- pore structure.Results: The study yielded significant results based on the analysis of pore diameter and throat radius. Pores were systematically categorized into four types (P1 to P4), representing micro, small, medium, and large pores. Similarly, throats were classified into four types (R1 to R4), corresponding to bent sheet- shaped, sheet- shaped, constricted, and pore- narrowing throats. The quantitative evaluation, utilizing parameters such as fractal dimension, shape factor, Euler number, connectivity, apparent porosity, and pore- throat structure type, classified the eight samples into four levels (I, II, III, IV), providing a comprehensive assessment of the micro- pore structure.Conclusion:In conclusion, digital core technology, leveraging its powerful three- dimensional imaging and data processing capabilities, demonstrated effectiveness in accurately and quantitatively characterizing the three- dimensional pore structure in tight sandstone reservoirs. The research outcomes contribute valuable geological insights, establishing a robust foundation for the evaluation and optimization of tight sandstone gas resources.
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LEI Chuang, YIN Shiyan, DONG Guiyu, ZHANG Ying, WANG Yu, ZHANG Weihua, MA Zhigang
2024,70(1):2024010002-2024010002, DOI: 10.16509/j.georeview.2024.01.021
Abstract:
The Qinnan Sag in the Bohai Bay Basin is lowly explored, where hydrocarbon generation potential of source rocks is required detailed investigation to identify hydrocarbon exploration potential and exploration targets. Methods:Burial history, thermal history, and hydrocarbon generation history of source rocks at various subsags were reconstructed on BasinMod software based on reasonable geological model and parameters derived from geological analogy. Results:Source rocks in the Eastern Subsag were mature at early stage due to differential subsidence and sedimentation, which was lasted for a long period and was currently at maturity to high maturity stage (Ro=1.0%～2.0%) . Two hydrocarbon generation events were occurred to them in the Oligocene and Miocene, respectively, with intensive hydrocarbon generation capacity. Source rocks at the Southeastern Subsag were mature at later stage, which was lasted for a short period and was currently at medium maturity stage (Ro=0.7%～1.0%). Hydrocarbon generation was primarily occurred since the late Miocene, with intensive hydrocarbon generation capacity. Source rocks at the Western Subsag were generally at low maturity stage (Ro＜0.7%), which began to generate hydrocarbon since Pliocene, with weak hydrocarbon generation capacity. The hydrocarbon generation capacity of source rocks is generally in an order: Es3>Es1>Ed3. Conclusions: The Qinnan Sag has high oil and gas exploration potential, where exploration activities should focus on effective traps located in the dominant migration direction of the depression and slope zones in the Eastern and Southeastern Subsags.
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MUREDILI Mahemuti, LIU Xiaoqiang, ZHANG Chuanlin, YANG Zhihao, HE Chao
2024,70(1):2024010003-2024010003, DOI: 10.16509/j.georeview.2024.01.035
Abstract:
In order to provide constraints for the Miocene tectonic evolution and deep dynamic process in the SE Pamir area, the age of the intrusive rocks in the Reskam area is redetermined and the petrogenesis and magmatic processes are discussed.Methods: Combined with field work and microscope observation, analysis of the LA- MC- ICP- MS zircon U- Pb isotopic dating, XRF major elements, ICP- MS trace elements, MC- ICP- MS Sr—Nd isotopes, LA- MC- ICPMS zircon Lu—Hf isotopes are carried out.Results: Zircon LA- MC- ICP- MS U- Pb dating results show that these magmatic rocks were emplaced at Miocene (12.0 ± 0.3 Ma). Geochemically, they have high SiO2 (72.14% ~ 74.35%) and high K2O (3.78% ~ 5.25%) contents, with low MgO (0.13% ~ 0.50%) and Mg# value (18 ~ 35). They exhibit high Sr (363×10-6~754 ×10-6), low Y (3.41×10-6 ~ 16.4 ×10-6) and Yb (0.327×10-6 ~ 0.903 ×10-6), thus high Sr/Y (27 ~ 188) and (La/Yb)N (18.95 ~ 210) ratios, in keeping with the typical adakites. In terms of isotopes, they have significantly enriched in situ zircon εHf(t (-10.1 ~ -5.4) and whole-rock εNd(t ( -8.33 ~ -6.39 ) values.Conclusions：The Reskam monzogranite was formed in the Miocene (~ 12 Ma) and has the characteristics of Adakite. The continuous subduction of the Indian plate significantly thickened the crust in the Pamir area. At around 12 Ma, due to the tectonic transformation of the Karakoram fault, the local detachment of the thickened lithospheric mantle in the Pamir area resulted in tectonic extension, triggering the upwelling of the asthenosphere and partial melting of the thickened ancient lower crust.
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QIN Hexing, CHENG Lei, LU Chang, HU Yue, XIONG Min, TAN Xiucheng, JI Yubing, CHEN Xin, WANG Gaoxiang
2024,70(1):2024010004-2024010004, DOI: 10.16509/j.georeview.2024.01.002
Abstract:
To further investigate the provenance, weathering, and tectonic setting of the Late Ordovician—Early Silurian black shale in the southern margin of the Upper Yangtze area, this study systematically sampled typical outcrops, analyzed the geochemical characteristics of major, trace, and rare earth elements in the Wufeng—Longmaxi Formations shale, and explored its geological significance.Methods: By analyzing the major, trace, and rare earth elements of 22 samples from the Wufeng—Longmaxi Formations shale in the outcrops of the southern margin of the Upper Yangtze area, this study reconstructed ancient weathering intensity and paleoclimate conditions, unveiled the provenance and tectonic setting, and investigated the shale formation environment and processes. These findings provide compelling geochemical evidence to support further exploration and development of the Wufeng—Longmaxi Formations shale in the Upper Yangtze area.Results: The black organic- rich shale of the Wufeng—Longmaxi Formations in the southern margin of the Upper Yangtze area exhibited characteristics such as low abundance of high field strength elements and enrichment of the large ion lithophile elements akin to the Upper Continental Crust. The ∑REE values ranging from 103.66×10-6~295.98×10-6, with an average of 180.57×10-6, indicated generally high rare earth element content. The standardized distribution pattern of the rare earth elements closely resembled that of the Upper Continental Crust, demonstrating a ‘V’ type pattern with rightward skew, enrichment of light rare earth elements, flat heavy rare earth elements, clear differentiation between light and heavy rare earth elements, and a distinct negative Eu anomaly. Moreover, the contents and ratios of characteristic trace and rare earth elements, such as La, Ce, La/Yb, and Sc/Cr, closely align with the characteristic values of the Passive Continental Margin. The ICV values ranging from 0.55 to 14.1, with an average of 2.28, and the Zr/Sc versus Th/Sc ratios suggested that the source was the result of initial rapid sedimentation of the tectonic belt, without indications of sedimentary recycling. Furthermore, the lower CIA values (ranging from 54.89 to 71.61, with an average of 65.27), A—CN—K and K2O/Al2O3 versus Ga/Rb ratios suggested minimal impact from chemical weathering on the provenance, and indicated a cold and dry sedimentary environment. The high contents of K2O, Rb, Al2O3/TiO2, and the negative Eu anomaly pointed toward a provenance dominated by felsic igneous rocks and acidic geological bodies such as granites. Conclusions:Based on the discriminant diagram of provenance and tectonic setting, it was inferred that the Wufeng—Longmaxi Formations shale in the southern margin of the Upper Yangtze area originated in the Passive Continental Margin. The predominant provenance was the early Neoproterozoic platform caprock of the Kangdian ancient land to the west, with partial contributions from the Qianzhong uplift, alongside the inflow of intermediate—acid volcanic materials from the southeastern Yangtze area.
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SHI Jiansheng, XU Yuan, LI Hui, YAN Changhong, HOU Jue, YU Liangchen, ZHAO Huaxin, CUI Wanghong, XU Chenghua, LIU Gang
2024,70(1):2024010005-2024010005, DOI: 10.16509/j.georeview.2024.01.025
Abstract:
With the development and utilization of underground space resources, more and more deep foundation pits present the characteristics of deep excavation, large scale, irregular shape, etc., and their supporting structure design is complicated and construction is difficult, with obvious spatial effects. This paper takes a pit project of Nanjing subway as an example to analyze the impact of pit construction on neighboring bridges. The site is located in the lower reaches of the Yangtze River diffuse phase binary structure stratigraphy distribution section, the upper soft soil layer thickness is large, the lower pressurized aquifer water table is high, rich in water, geological conditions are very complex, the pit is a typical deep and large heterogeneous pit, away from the hyperbolic arch approach bridge is only 7.2 m, due to the bridge has been subjected to other underground engineering construction produced by a large deformation, the deformation that can be withstood is close to the critical value, so the subsequent project on the neighboring bridge. For this reason, the station pit support structure design based on the actual function of the underground space by setting partition wall partition excavation and MJS ultra- deep method wall comprehensive deformation control program. In this paper, by taking finite element numerical simulation to carry out the deformation prediction analysis of enclosure structure and bridge pile foundation caused by pit excavation in complex environment, the calculation results show that this deep, narrow and long shaped pit excavation has significant effect on settlement deformation of neighboring bridges, and the deformation control through the setup of partition wall subdividing excavation and MJS method wall can control the spatial effect of the pit and reduce the "long side effect", " heteromorphic effect" and other effects on the bridge settlement deformation. The feasibility of this comprehensive deformation control program is verified through the actual monitoring results of the on- site foundation pit excavation process. The research results are of good reference significance for the support and construction design of deep, narrow and long shaped foundation pits under similar complex geological conditions.
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2024,70(1):2024010006-2024010006, DOI: 10.16509/j.georeview.2024.01.005
Abstract:
Since the South- to- North Water Diversion Project Central Route was first operated in December, 2014, continuous groundwater recharge makes great contribute to preventing and slowing down the development of land subsidence. However, the influencing factors and the mechanism of land rebound response to the groundwater rise are not yet clear.In- depth exploration and study of the relationship between recharge time, recharge volume, recharge location and water level and land deformation,understanding the mechanism of land deformation,and identifying the primary factors, is of great significance for the follow- up of how to recharge scientifically, maximize the benefits of water recharge, and prevent and control land subsidence and the management of overexploitation areas. Methods:This paper takes the middle and upper area of Chaobai River alluvial fan as an example, adopts permanent scatterer differential interferometry (PS- InSAR) technology to obtain the information of land deformation, and coupling with the multi- groundwater monitoring well and extensormeters and other means of , to find out the response and controlling factors of the ground surface deformation in the study area and the multi- factors.Results: The findings indicate that (1) the region's land subsidence is slowed down by the south water's constant replenishment, and that the Niulan Mountain region experiences surface uplift. With the rise in water level, the uplift area also gradually widens to the middle and downstream, and the maximum rebound rate reaches 46.9mm/a in 2022.Conclusions:The Houshayu depression, which is split by the Huangzhuang—Gorliying fault, Shunyi fault, and Nankou—Sunhe fault, has undergone more alterations than other regions because for any particular characteristics of Quaternary depositional differences governed by faults；The range and responsiveness of water level rise are determined by variability in groundwater level amplitude and water richness, and the direction of groundwater flow is somewhat controlled by quaternary sedimentary differences brought on by sedimentary tectonics.
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WANG Daojun, LIU Zhujiang, CHEN Chao, LIU Xiaojing, LIU Miaomiao
2024,70(1):2024010007-2024010007, DOI: 10.16509/j.georeview.2024.01.001
Abstract:
The shale oil and gas resources in the Lower Jurassic Lianggaoshan Formation in the Sichuan Basin have great potential, among which the Qijiang area in southern Sichuan is a favorable resource replacement position. Through comprehensive research, identify the lithological characteristics and enrichment conditions of the Lianggaoshan Formation in the Qijiang area, and guide the next step of oil and gas exploration in the study area.Methods: Based on the exploration of both passing wells and core sampling, as well as the re-examination of old wells, this study comprehensively analyzed the lithological characteristics and shale oil and gas enrichment conditions of the Lianggaoshan Formation in the study area through detailed description of core data, organic geochemistry, and geophysical data. Results: The semi- deep lacustrine rich organic matter shale in the Lower Submember, Lianggaoshan Formation, Lower Jurassic(L. Liang- 2 Subm.), in Qijiang area is stably developed, with a thickness ranging from 20 to 35 meters and an average TOCof 1. 40%, making it a favorable exploration layer. There are a total of 5 typical lithofacies developed in the target layer, among which the high carbon silty layer type sandy shale and medium carbon silty layer type sandy shale are the most advantageous shale lithofacies. High carbon fine sand layer type sandy shale and medium carbon fine sand layer type sandy shale have reservoir characteristics of “porous coexistence, large pores and throats, and integrated pores and fractures”. At the same time, they have relatively high TOC, high porosity, good oil and gas properties, and good compressibility, which have good geological conditions for shale oil and gas reservoir formation. The enrichment conditions for shale oil and gas in the L. Liang- 2 Subm. in Qijiang area have been identified: ① Favorable sedimentary environment controls the widespread development of advantageous lithofacies, with excellent shale quality and active oil and gas display. ② The thermal evolution degree of shale oil and gas reservoirs is moderate, with the development of micro cracks, which is conducive to the enrichment and flow of oil and gas. ③ The overall structure is stable, with a wide and gentle syncline, moderate burial, and good preservation conditions. It is pointed out that the Guanshengchang syncline is the most favorable exploration target for the next step.Conclusions: The L. Liang- 2 Subm. in the Qijiang area has developed high- quality shale lithofacies in semi- deep lacustrine facies, including high carbon fine sand layer type and medium carbon fine sand layer type, with “high- quality shale development, moderate thermal evolution, developed microcracks, and good preservation conditions”. Shale oil and gas enrichment conditions are good, and multiple favorable exploration targets are developed.
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WANG Deyuan, Jean BOTTAZZI, ZHOU Wenlong, LI Wei, HU Wanmei, LV Xiaoxi
2024,70(1):2024010008-2024010008, DOI: 10.16509/j.georeview.2024.01.032
Abstract:
The giant panda was widely distributed in South China during the Late Pleistocene, with numerous fossil sites, but relatively few intact skeletal materials. We report the newly discovered complete giant panda skull fossil in Yangtianwo Shaft, Huishui, Guizhou, and analyze its burial characteristics combined with cave features.Methods: We have carried out detailed cave survey and cave mapping of Yangtianwao—Baima Cave system. The teeth of giant panda were studied in detail by morphological measurement and compared with those of Ailuropoda melanoleuca baconi and modern giant pandas (Ailuropoda). The fractured bone fragments were dated by AMS—14 C dating method.Results: There are favorable conditions for the preservation of fossil in the Yangtianwo Shaft — Baima Cave system because of its special cave environment. According to the measured data, the teeth of Yangtianwo giant panda are slightly larger than those of modern giant pandas, and should belong to the Ailuropoda melanoleuca baconi. The AMS—14 C dating results are 22887~22431 a BP, which is around the last glacial maximum.Conclusions:The discovery of new materials provides rare physical evidence for the distribution range, survival and evolution of giant pandas at the end of the late Pleistocene.
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2024,70(1):2024010009-2024010009, DOI: 10.16509/j.georeview.2024.01.045
Abstract:
The Zhongtiao Mountains, an important part of the Trans-North China Orogen, North China Craton, holds well preserved significant evolution records of the Trans-North China Orogen. The Jiangxian Group is divided into the Henglingguan Subgroup and the Tongkuangyu Subgroup, the Henglingguan Subgroup consists predominantly of metamorphic clastic rocks, specifically quartzite and phyllite. In contrast, the Tongkuangyu Subgroup primarily comprises acid and basic volcanic rocks, with “bimodal” volcanic rocks alternating with normal sedimentary clastic rocks. Based on field investigation on the rock composition and stratigraphic characteristics and comprehensive analysis of zircon isotopic ages of the volcanic rocks, intrusive rocks, and detrital zircon of the Jiangxian Group, the age for this Group is estimated to be around 2200 ~2120 Ma, corresponding to the Paleoproterozoic Era. By integrating the geochemical characteristics of clastic and volcanic rocks with the evolutionary history of the Trans-North China Orogen, it is inferred that the Jiangxian Group likely originated in a tectonic setting linked to a paleo-active continental margin. Specifically, the Henglingguan Subgroup was deposited in an active continental margin basin, whereas the Tongkuangyu Subgroup originated in a volcanic arc of an active continental margin.
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WANG Zhenghe, ZHANG Ronghu, YUE Yong, YU Chaofeng, YANG Zhao, ZHI Fengqin
2024,70(1):2024010010-2024010010, DOI: 10.16509/j.georeview.2024.01.012
Abstract:
The third- order sequence division of the Lower Silurian Kepingtage Formation in the Tarim Basin was different based on different research locations or areas, which restricted the understanding of the regional tectonic—sedimentary evolution and the direction of oil and gas exploration of these strata. So it is necessary to analysis the sedimentary characteristics and divide the third- order sequence of these strata again.Methods: In order to reasonably divide its third- order sequence, we have combined with all data of outcrops, published wells and seismic, existing research results, the detailed analysis of the sedimentary and sequence characteristics of the outcrop of the Kepingtage Formation in Aqia area, Keping County.Results: ① The Kepingtage Formation in Aqa area is mainly a delta sedimentary system controlled by mixed hydrodynamics dominated. From bottom to top, the lower member is a sedimentary cycle from fining- up to coarsing- up, and the middle and upper members form a coarse- up sedimentary cycle as a whole. ② The unconformity surfaces at the top, bottom and inside of the Kepingtage Formation can divide it into two third- order sequences. The lower member constitutes SQ1, with LST, TST and HST. The middle and upper members constitute SQ2, with only TST and HST.③ The boundary between the middle and the lower members of the Kepingtage Formation may correspond to the unconformity formed by the sea level decline during the glacial period in the Late Ordovician Hernantian.④ As the hydrodynamic conditions of different system tracts are different, the LST is dominated by river effect, while the wave and tide effect is greater than the river effect in HST. ⑤ TST in SQ2 is a regional high- quality cap rock, which can form a good cap-reservoir combination with HST in SQ1. Therefore, HST of SQ1 in the western Awati sag can be the primary exploration target in this strata.Conclusions:In Aqia area, the Kepingtage Formation belongs to a delta sedimentary system formed with the mixed hydrodynamics, and it can be divided into two third- order sequences. The study has a new significance for oil and gas exploration about these strata.
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ZHANG Yanxia, SUN Yejun, CHEN Jun, CUI Weisheng, CHEN Shuqing, WANG Zengtao
2024,70(1):2024010011-2024010011, DOI: 10.16509/j.georeview.2024.01.022
Abstract:
There is a complete avian footprint (ZDRC. F3) preserved in the Lower Cretaceous at the Zhangzhuhewan dinosaur footprint site in Zhucheng, Shandong Province. It had been briefly described and classified as the Jindongornipes sp. This article conducts a detailed systematic paleontological study of the footprint, and preliminary reconstruct the paleoenvironment and paleogeography of the Zhangzhuhewan dinosaur footprint site.Methods:A detailed feature description of the avian footprint in Zhangzhuhewan dinosaur footprint site was conducted using observation and measurement methods, and their morphological characteristics and related parameters were compared with the footprint of the Jindongornipodidae, analyzing the similarities and differences between the two. Based on regional geology, preservation characteristics of dinosaur and avian footprints, and layer structures, the paleogeography and paleoclimate of their survival period are reconstructed, and the formation environment and process of the avian footprint are speculated.Results: There are significant differences in the footprints between ZDRC.F3 and Jindongornipodidae: ① ZDRC.F3 is a small footprint with a width of 2.9 cm, less than half of the bird family footprint in Jindongornipodidae, and not within the range of 6.5~ 7.5 cm in width; ② The digit Ⅱ is slightly longer than the digit Ⅳ, which does not conform to the characteristic of the Jindongornipodidae that the digit Ⅱ is shorter than the digit Ⅳ. ZDRC.F3 was removed from Jindongornipodidae and a new genus and species of Zhuchengornipes exquisitus gen.et sp.nov was established. The regional geology and characteristics of dinosaur and avian footprints and mud cracks indicate that Zhangzhuhewan dinosaur footprint site is located at the edge of a giant lake basin. The slope of the lake edge is small, and the lake water is shallow at Zhangzhuhewan site. During the dry season, the evaporation of the lake water exceeds the precipitation. Intermittent droughts occur at the edge of the lake, resulting in large areas of lakeside beaches exposed to the air. At that time, bird living nearby left footprints on the lakeside.Conclusions:Zhuchengonipes inquisitus gen. et sp. nov. is a new type of avian footprint that differs from the avian footprints previously discovered and may have been created by shorebirds. The avian footprint was formed in the coastal and shallow lake environment of arid climate in the Early Cretaceous.
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CHEN Jingpeng, KANG Fengxin, HAN Jianjiang, JIANG Shujie, WANG Mingzhu, WANG Weilong, DUAN Xiaofei
2024,70(1):2024010012-2024010012, DOI: 10.16509/j.georeview.2024.01.055
Abstract:
Jiaodong Peninsula is a typical water- scarce mountainous area in China, where magmatic rocks, metamorphic rocks and chalk impervious sandstones are widely distributed, and aquifers differ greatly in water richness. Meanwhile, there are intensive human activities in Jiaodong Peninsula, and the problem of poor water quality caused by poor water quality is also prominent, and resource- based water shortage and water quality poor water shortage problems exist simultaneously，In order to reveal the water storage structural model and water seeking direction of typical water- scarce mountainous areas under the influence of human activities.Methods:The hydrogeological survey conducted in the typical water- scarce mountainous areas of Jiaodong Peninsula from 2019 to 2022, using 7 groups of borehole data , 7 groups of hydrochemical and isotope analysis samples from this construction, based on the theory of water storage structure and combined with the water chemical and isotope characteristics under the influence of human activities, the water richness of different types of water storage structures and the influence of human activities represented by nitrate on water quality were compared.Results:In this paper, the structure of the water storage structure of the depression, the contact band, the fracture and the karst type are summarized.It is revealed that the nitrate content of the weathered fissure water represented by the weathered water storage structure in the depression and gully is increased and the water quality is poor due to human activities ,It also revealed that the water is susceptible to human activity, the nitrate content is raised, the water quality is poor, the complete bedrom of the confined water layer is the influence of human activity on the groundwater, the low nitrate content and the water quality.The upper intact bedrock of structural fissure water (confined water) represented by fault- type water storage structure acts as a water barrier covering layer, which weakens the influence of human activities on groundwater, and has low nitrate content and good water quality.Conclusions:The fault- type water storage structure- confined water is suitable for urban and rural domestic water, while the weathered water storage structure—weathered fissure water in depressions and valleys is suitable for industrial and agricultural production. The development and utilization direction of contact zone type and karst type water storage structure is related to the buried depth of aquifer.
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CHENG Jiankang, SUN Baowei, HUO Jiaqing, XIAO Liang, WANG Bin, ZHU Kaining
2024,70(1):2024010013-2024010013, DOI: 10.16509/j.georeview.2024.01.065
Abstract:
This paper focuses on the study of petrology and geochemistry of the newly discovered bimodal volcanic rock assemblage in Mount Bailin area,Yanyuan County,Sichuan Province, and discusses its petrogenesis and tectonic geological background,which provides new clues and geological basis for further research on the formation mechanism,tectonic evolution and mineralization of Emeishan large igneous province.Methods:On the basis of field investigation,representative samples of basic and acid volcanic rocks were collected,and the bimodal volcanic rocks were studied by microscopic observation,analysis of major elements,trace elements and rare earth elements,and the petrogenesis and tectonic environment of the bimodal volcanic rocks were discussed.Results:A bimodal volcanic rock composed of alkali- rich high- titanium basalt and pantellerite was newly discovered in Mount Bailin area of Yanyuan County,Sichuan Province.It belongs to a part of the Emeishan large igneous province and was formed in the late Permian.Both basalt and pantellerite are characterized by light rare earth enrichment.The rare earth content and fractionation degree in pantellerite are significantly higher than those in basalt,and pantellerite shows obvious negative Eu anomaly.The basalts are relatively enriched in high field strength elements such as U,Th,Nb and Ta, and relatively depleted in large ion lithophile elements such as Rb,K and Sr.The pantellerite are significantly enriched in high field strength elements such as U,Th,Nb,Ta,Zr and Hf, and severely depleted in Ba,K,Sr,P,Ti,Ni and Cr.Basalt is the product of partial melting of mantle peridotite to a small extent.Pantellerite is mainly formed by acidic residual magma after extreme separation and crystallization of basaltic magma.The basalt were formed in the oceanic island environment,and the pantellerite were formed in the intracontinental extensional environment.The tectonic environment is related to the activity of the Emeishan mantle plume and the intracontinental rift extension by it.Conclusions:The definition of the late Permian bimodal volcanic rocks in Mount Bailin area,Yanyuan County,Sichuan Province is of great significance for the study of regional tectonic evolution and mineralization and the expansion of prospecting ideas.
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ZHANG Yan, FANG Weixuan, XU Lingang, CHEN Wen, ZHANG Zhibing, YE Huishou, LIU Lihong, WANG Wenhao, ZHAO Liangliang, WU Haoran
2024,70(1):2024010014-2024010014, DOI: 10.16509/j.georeview.2024.01.042
Abstract:
Redox Sensitive Trace Metals and Bio- essential elements can deposit and formed special sedimentary mineral deposits in special sedimentary setting. Deep understanding the important elements geochemistry, relevant sedimentary mineral deposits and their spatial and temporal distribution characteristic, can improve our cognition between the old ocean evolution and sedimentary mineral deposits formation.Methods: In this paper, we reviewed relevant elements migrate and concentrated regulation, and redox discrimination methods which included pyrite morphology, and biological productivity and basin limitation discrimination methods. Then we centralized summarized Nanhuan to early Silurian sedimentary Mn, P, Ni—Mo—Co, V and U mineral deposit around Yangtze Block in genetic, distribution and the relation to lithofacies palaeogeography, under the background of global oxidation envent, glacial—interglacial envents, Rodinia supercontinent break up envent, metallogenic metal elements in the ocean accumulated during a long geology history. Results and Conclusions:So the sedimentary minerals in Yangtze Block margin from Neoproterozoic to early Paleozoic is the natural laboratory to ① research Redox Sensitive Trace Metals and Bio- essential elements action in different sedimentary environment, and ② metallogenic mechanism and the contribution of seawater—biology—hydrothermal fluid end members. At last, to solve the problems in sedimentary ore deposits study of Yangtze Block, we proposed solutions and future prospecting.
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JING Ming, GAO Pengxin, WANG Zengxiang
2024,70(1):2024010015-2024010015, DOI: 10.16509/j.georeview.2024.01.075
Abstract:
Physical geological data is a valuable resource formed by geological exploration work. Ensuring the safe and proper storage of important physical geological data is an important guarantee for achieving effective preservation and efficient utilization of their potential value. However, how to improve the contradiction between the growing demand for important core storage and limited warehouse construction is an urgent issue facing the current work of physical geological data storage in China. The paper systematically summarizes the important achievements made in the system construction and warehouse construction of physical geological data storage in China in recent years, analyzes the main problems currently faced, and studies and proposes suggestions on the overall layout and mechanism construction of physical geological data storage in China, providing reference for improving the overall storage capacity of physical geological data in China
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2024,70(1):2024010016-2024010016, DOI:
Abstract:
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HE Zhongbo, HU Baoqun, JI Huali, HE Feng, GENG Yingying, HUANG Shaohua, ZHU Manhuai
2024,70(1):2024010017-2024010017, DOI: 10.16509/j.georeview.2024.02.032
Abstract:
Analyzed the geochemical analysis data of major elements, trace elements, and rare earth elements (REE) of the Lower Cretaceous sandstone, we studied its sedimentary cycle characteristics, chemical weathering, structural background, and material sources of the sandstone.Methods:Based on the geochemical analysis of major elements, trace elements and rare earth elements (REE)of the Lower Cretaceous sandstone in Zhenyuan area of Ordos Basin, this paper discusses the sedimentary recycling characteristics, chemical weathering, tectonic background and material source of the Lower Cretaceous red variegated sandstone. Results: ① The Lower Cretaceous Luohe Formation, Huanhe Formation and Luohandong Formation are similar in provenance main body, and have good inheritance in structural background, provenance area and provenance characteristics. The REE distribution pattern curves of rare earth elements are consistent, with clear fractionation of light and heavy rare earth elements, enriched in large ion lithophile elements Ba, Pb, Sr, and light rare earth elements, and depleted in high field strength elements Nb, Ta, Th, Y, etc. From bottom to top, with the formation becoming newer, the total REE content in Sedimentary rock tends to decrease, and the fractionation degree of heavy REE decreases. ② The original material of the Lower Cretaceous sandstone in the study area is mainly composed of felsic and mafic mixed rocks (such as intermediate—acid intrusive rocks, felsic metamorphic rocks) and some sedimentary rocks. ③ In the tectonic setting, the passive continental margin tectonic environment is the main advantage. The debris mainly comes from the continental source area, followed by the recycled orogenic belt and the mixed source area.Conclusions: The provenance area is generally characterized by rich quartz, rich Calcite cement, more potassium feldspar or potassium rich minerals than plagioclase. The Luohandong Formation is more siliceous than Huanhe Formation and Luohe Formation, with less Calcite cement and purer quality. Most of the sediments in the study area are transported by the weathering and denudation products of the parent rock in the thrust nappe zone on the southestern margin of the Ordos Basin, Which are the first sedimentary materials. A few sediments (i.e. Aeolian sand) are formed by in- situ re- transport and accumulation, which are recycled sedimentary materials.
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HU Hewei, XU Peng, YU Haibo, LIAN Haojie, JI Xinyuan, DING Yiran, SHAO Longyi
2024,70(1):2024010018-2024010018, DOI: 10.16509/j.georeview.2024.02.011
Abstract:
The sandstone reservoirs of the braided river delta facies are developed in the 2nd Member of the Paleogene Shahejie Formation (Sha- 2 Member) in the steep slope zone of the Shanan Sag, the Bohai Bay Basin. The reservoir is influenced by structural location, burial rate, paleotemperature changes, and faulting, and its physical properties vary significantly in different structural areas, especially in the middle—deep layers. In this paper, the sedimentary facies, diagenesis, and pore evolution characteristics of the middle—deep sandstone reservoirs are studied by using the data of drilling, logging, seismic, and laboratory analysis, and the main controlling factors and evolution regularities of the high- quality reservoirs are proposed. The results show that the middle—deep sandstones in the study area are mainly lithic arkose, and the pore spaces are mainly intergranular dissolved pores. There are four types of reservoirs, i.e., the medium porosity—medium permeability type, the medium porosity—low permeability type, the low porosity—low permeability type, and the low porosity—ultra- low permeability type. The medium porosity—medium permeability type is the main one in the area. The pore space of the reservoir is generally well developed, being characterized by a medium porosity and a medium permeability, supporting a good physical property. Further investigation has revealed the major controlling factors of the high- quality reservoirs. The provenance rock rich in quartz and feldspar is the material foundation, the delta plain distributary channel is the favorable sedimentary facies type, and the strong dissolution of calcite cement during the late diagenesis provides major pore space, all of which play the key role in the development of the high- quality reservoir. The analysis of the spatio—temporal distribution of the high quality reservoirs shows that, in the Caofeidian 14- e structure area in the southern sub- sag of the Shanan Sag, the braid river delta facies sandstones are developed and these sandstones are surrounded by the effective source rocks. These conditions are superior to the hydrocarbon migration and accumulation, demonstrating a great potential of the lithologic reservoir exploration potential in the Caofeidian 14- e structure area. The presence of thick oil layer has already been proved by drilling, which indicates that this area is most favorable for exploration of lithologic reservoirs in the Shanan Sag.
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HUO Chao, WANG Lei, XIE Zhiqing, PAN Haiyang, FANG Huiming, ZHAO Yue, WANG Dandan, WANG Danfeng
2024,70(1):2024010019-2024010019, DOI: 10.16509/j.georeview.2024.02.001
Abstract:
Long- term large- scale exploitation of coal resources in China has produced a large number of underground spaces. Directly shutting it down will not only waste underground space resources, but also cause a series of safety, environmental and economic problems. Therefore, how to scientifically and efficiently solve the comprehensive development and utilization problem of underground space in coal mines is of great practical significance for the development of the coal industry and even the national economy. This article takes the main coal producing provinces as representatives and combines the latest data collected from research on production and closure of coal mines to deeply analyze the overall situation of underground space in production and closure of coal mines during the 13th Five Year Plan period. It systematically summarizes the current functional utilization status of underground space in coal mines at home and abroad in terms of storage and energy storage, and points out the scattered resource data information in the current utilization of underground space in coal mines in China, the overall development and utilization rate is low, related technology research work is still relatively lagging behind, and there are few mature demonstration projects available for promotion and reference. Four key development directions have been proposed in the new era, including the construction of coal mine underground space basic database, utilization system construction, key technology research, and demonstration project promotion.
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JI Huali, HE Zhongbo, ZHONG Jun, CHEN Hong, ZHU Bin, WU Yu, DONG Qian, GENG Yingying
2024,70(1):2024010020-2024010020, DOI: 10.16509/j.georeview.2024.02.022
Abstract:
By combining outcrop, core, and logging, the sedimentary characteristics and sand body development characteristics of the Lower Cretaceous were finely characterized, and the exploration direction of sandstone type uranium deposits in the Wuerhe—Huanghuagou area was explored.Methods: Based on the comprehensive analysis of outcrops, drilling cores, drilling and logging in the Wuerhe—Huanghuagou area on the northwestern margin of the Junggar Basin, combined with microscopic observation, the main petrological characteristics, stratigraphic structure, sedimentary facies types and distribution characteristics of the Lower Cretaceous Tugulu Group were comprehensively analyzed. Guided by the metallogenic theory of sandstone- type uranium deposits, the types and distribution of favorable ore- forming sand bodies in the Lower Cretaceous Tugulu Group in the study area were discussed from the perspective of sedimentology. Results: ① The rock types of the Lower Cretaceous Tugulu- a Subgroup in the study area are mainly feldspar lithic sandstone and lithic feldspar sandstone, while the Tugulu- b, Tugulu- c and Tugulu- d subgroups are mainly feldspar sandstone and feldspar lithic sandstone. ② There are four types of sedimentary facies in the Lower Cretaceous Tugulu Group in the study area, which are alluvial fan, braided river, delta and lake, its provenance is from the northwest of Semistan Mountain. With the Delunshan as the boundary, the Wuerhe—Xiazijie area is dominated by shallow- water delta deposits with far- source weak current, while the Delunshan—Huanghuagou area is dominated by high- energy braided river deposits, its provenance should come from the northern part of the basin. ③ The favorable prospecting horizon of the Lower Cretaceous is the primary gray—gray green coarse clastic formation of the Tugulu- a+Tugulu- b Subgroup. Conclusions: The branch channel of delta plain subfacies in Wuerhe—Youshashan area is an important prospecting direction. The underwater distributary channel of delta front and the thick sand body of sheet sand widely developed in the Xiazijie area have good lateral extensibility, it has the ability to form a certain scale sandstone- type uranium deposit.The Huanghuagou area developed a wide and large- scale braided river sand body in the Tugulu- a+Tugulu- b period, which is a favorable area for interlayer oxidation and phreatic oxidation.
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LI Yichao, GONG Chenglin, QIU Xinwei, QI Peng, HE Yanbing, YU Yixin
2024,70(1):2024010021-2024010021, DOI: 10.16509/j.georeview.2024.02.021
Abstract:
Quantitative analysis of the source- to- sink system is the leading edge of the field of sedimentology, and is of great significance for accurate reconstruction of source- to- sink process and prediction of hydrocarbon reservoirs. Methods:We use the heavy mineral assemblages and zircon U- Pb ages to trace the provenance of the Huizhou- 27 transfer zone in the Huizhou Sag, Pearl River Mouth Basin, and quantitatively reconstruct the sediment contribution of potential source areas. In addition, we reveal the source- to- sink process and discuss the control of source- to- sink system on the hydrocarbon reservoir. Results: The results show that the heavy mineral assemblages of the middle Eocene Wenchnag Formation are complex with low ZTR values（the ZTR index is the percentage of detrital zircon, tourmaline and rutile in the transparent heavy mineral detritus of a clastic rock）, while the heavy mineral assemblages of the upper Eocene Enping Formation are relatively simple with high ZTR values. This study further confirms that the Wenchang Formation to the Enping Formation were mainly fed by intrabasinal Mesozoic magmatic basement and extrabasinal Pearl River system. For the Wenchang Formation, ca. 98% sediments were derived from the intrabasinal Mesozoic magmatic basement; for the lower Enping Formation, ca. 58.4% sediments were derived from the northeastern tributaries of the Pearl River, while ca. 36.5% sediments were derived from the intrabasinal Mesozoic magmatic basement; for the upper Enping Formation, ca. 73.7% sediments originated from the northeastern tributaries of the Pearl River, while ca. 22.2% sediments originated from the intrabasinal Mesozoic magmatic basement. Conclusions:We infer that the modern Pearl River system, including the northeastern and western tributaries, was not yet formed during the depositing of the Enping Formation, but the northeastern tributaries (i.e., the paleo- Pearl River) had developed independently. Rather than a simple provenance transition from intrabasinal to extrabasinal, the paleo- Pearl River transported abundant sediments from the Cathaysia Block into the Huizhou Sag, resulting in the transition of the source- to- sink system from “the Wenchang Formation with intrabasinal provenance” to “the Enping Formation with mixed provenance”. This transition of source- to- sink system changes the rock composition of reservoir in the Enping Formation, which improves the reservoir physical properties but enhances the reservoir heterogeneity. This study presents a quantitative analysis of the transition of the source- to- sink system in the Paleogene Huizhou Sag, and provides insights into the quantitative source- to- sink process and its applications in continental rift basins.
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WANG Jinfang, LIU Chenyu, LU Zeqian, LI Kangshuo, SONG Yutong, LI Yingjie, CHEN Gongzheng
2024,70(1):2024010022-2024010022, DOI: 10.16509/j.georeview.2024.02.025
Abstract:
The closure time of the Paleo—Asian Ocean ( PAO ) on the northern margin of North China Plate is still unclear. The Liangtou monzogranite in Zhangbei area of northern Hebei Province is located in the central part of the northern margin of the North China Craton( NNCC )，and has important implications for the PAO closure. This study carried out zircon LA- ICP- MS U- Pb geochronology and geochemistry on the monzogranite to discuss its origin，in order to provide new evidence for the closure time of the PAO. Methods: Based on petrology，geochemistry，LA- ICP- MS zircon U- Pb geochronology and Hf isotopic composition，this paper discusses the petrogenesis and tectonic setting of the Liangtou pluton, and the closure time of the PAO. Results:The zircon U- Pb LA- ICP- MS dating shows that the age of the monzogranite is 262.5±2.6 Ma，indicating that the pluton was emplaced in the Late Permian. The rock has higher SiO2 (70.27% ~ 73.89%)，Na2O (4.2% ~ 4.55%)，K2O (3.87% ~ 4.64%)，Sr (417×10-6 ~ 827×10-6)，and lower Yb (0.286×10-6 ~ 0.518×10-6)，Y (2.74×10-6 ~ 6.98×10-6) contents. The zircon εHf (t) values range from -17.50 to -11.12，with two- stage model ages (tDM2) of 1989 ~ 2390 Ma.Conclusions: The Liangtou pluton belongs to adakitic rock and arc magmatite formed in the active continental margin arc setting. It indicates that the PAO may still be in the process of subduction towards the NNCC during the Late Permian(262.5±2.6 Ma)，and its final closure time may have been at the end of the Late Permian.
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WANG Xiaoliang, ZHAO Yuanyi, ZHAO Xitao, CHEN Jundian, WU Wenbin
2024,70(1):2024010023-2024010023, DOI: 10.16509/j.georeview.2024.02.012
Abstract:
River terrace is good carrier for the study of river evolution and tectonic movement. Although the Quaternary geology in Beijing area is highly studied, there are few relevant research data on river terrace in the east of Beijing. In this paper, the Juhe River, Huangsongyushi River and Jiangjunguanshi River developed in front of Yanshan Mountains, are taken as the research objects in Pinggu area, Beijing. Methods: The development sequence of the above- mentioned river terraces is divided in detail. On this basis, the formation times, terrace genesis and the response of river terraces to the uplift of the Yanshan Mountains are discussed by field geological survey and opto—luminescence dating (OSL). Results: It is considered that the Juhe River developed three terraces on the south bank and developed two terraces on the north bank. The Huangsongyushi River developed 6 terraces. The Jiangjunguanshi River developed 5 terraces. The Jiangjunguanshi River was formed no later than the late Middle Pleistocene (161.7±7.7 ka BP) and the Huangsongyushi River was formed no later than the early Late Pleistocene (121.2±5.4 ka BP~100.3±4.1 ka BP). The Juhe River was formed no later than the middle of the Late Pleistocene (79.4±3.3 ka BP~70.8±3.4ka BP). The formation of the terraces of the Juhe River, Huangsongyu River and Junjiangguanshi River is influenced by paleoclimate change and the Yanshan Mountains uplift. The Yanshan Mountains in Pinggu area has been in a state of uplift since the late Middle Pleistocene, and the uplift rate reached the maximum in the early Late Pleistocene, up to 0.24 mm/a~0.34 mm/a, and decreased in the middle of the Late Pleistocene, to 0.18 mm/a ~ 0.24 mm/a.Conclusions: The above results have important reference value for the study of the development characteristics and formation times of river terraces in eastern Beijing, and also provide new evidences for the uplift of the Yanshan Mountains since the late Middle Pleistocene.
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YANG Tingting, XU Guangquan, ZHANG Zhu, LI Hao, ZHANG Jinsheng, HE Biao
2024,70(1):2024010024-2024010024, DOI: 10.16509/j.georeview.2024.02.002
Abstract:
The characteristics of paleokarst development and the restoration of paleomorphology are important for preventing and controlling karst water damage in coalfields in North China Craton. This study focuses on the paleokarst in the Ordovician System in Shungeng Mountain, Huainan City, which is located at the southern edge of the North China Craton.Methods: The characteristics of paleokarst development and the bedrock is undulating were revealed by field geological surveys, sectional profiling and residual thickness methods. Based on modern karst theory, the spatial variation patterns of different karst zones were analyzed from the perspective of their formation conditions, and the paleokarst landforms were restored.Results: The results show that the Lower Ordovician Majiagou Formation has mainly large karst channels and holes with little internal filling, while the Lower Ordovician Xiaoxian Formation has mostly interlayer karst along the level, filled with karst breccias. The internal filling calcite increases from east to west. The Ordovician palaeokarsts in the Shungeng Mountains weaken gradually from east to west and from top to bottom.Conclusions: The paleomorphology of the Ordovician System in Shungeng Mountain, Huainan City, is higher in the east and lower in the west and can be divided into four three- level karst geomorphic units： residual hills, gentle slopes, steep slopes and depressions. The paleokarst landscape from top to bottom was classified into superficial karst zone, vertical seepage zone, horizontal submerged flow zone and deep slow flow zone from shallow to deep, based on the karst geological conditions, groundwater runoff patterns and karst development characteristics. The superficial karst zones and vertical seepage zones of the residual hills and gentle slopes are the most developed, and large karst fissures often occur between the sedimentary layers, which may cause karst collapses when the groundwater flow changes.
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YIN Jin, WU Jinhao, Li Yuan, WANG Jian, ZHONG Wen, ZENG Tengfei, YANG Rong, CHEN Wei
2024,70(1):2024010025-2024010025, DOI: 10.16509/j.georeview.2024.02.015
Abstract:
The Jinyinshan lithium deposit is located in Chibi City, Hubei Province. The ore- bearing rocks are mainly silicified cataclasite, cataclastic silty slate, cataclastic argillaceous slate, metamorphic siltstone, and lamprophyre. It has been reported that the cookeite is found in the cataclastic silty slate in this area, However, there is a lack of research on the form of lithium in all ore- bearing lithology, especially in lamprophyre. The article selected all ore- bearing lithology in the area for scanning electron microscopy analysis, and it is believed that there are no mica minerals in this area. In situ X- ray diffraction (XRD) study was carried out and the characteristic peak of cookeite was found. In situ trace element analysis (LA- ICPMS) and other analyses have been carried out. It is found that Li and Al2O3 have a strong positive correlation, which confirms that lithium in this area exists in the form of cookeite. In addition, cookeite in this area is mainly filled between quartz grains or in olivine pseudocrystals, and its occurrence is scaly and bamboo leaves, It is completely consistent with the genetic characteristics of the hydrothermal cookeite, so it is inferred that cookeite in Jinyinshan mining area is of hydrothermal origin. As the Mufu Mountains complex rock body, which is closely related to rare metal mineralization, is about 15 km away from the south, the ore- forming materials may come from the southern rock body,In the subsequent process of mineral exploration, attention should be paid to searching for similar lithium deposits between the F9 fault and the rock mass.
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LIU Hansheng, YANG Boyong, YANG Liangzhe, WANG Di, WU Siqin
2024,70(1):2024010026-2024010026, DOI: 10.16509/j.georeview.2024.02.045
Abstract:
Abstract: Geoscience popularization plays a crucial role in implementing General Secretary Xi Jinping’s “Two-Wings Theory”, disseminating knowledge of Earth sciences, enhancing scientific literacy among the public, and facilitating comprehensive geological services to society. Comprehensive and accurate geological data serve as the foundation for successful geoscience popularization. This article adopts a discursive approach to analyze the significance and advantages of provincial Geo-Prospecting units engaging in geoscience popularization work. Using the example of the Hubei Insititute of Geosciences, it introduces its achievements in creating a popularization brand, conducting popular science content creation, and organizing popular science activities. It also examines how provincial Geo-Prospecting units can fulfill their public welfare functions, promote government cooperation, and meet market demands through geoscience popularization. Feasible development recommendations are proposed, aiming to explore an innovative development path for provincial Geo-Prospecting units that allows them to play a geological role while simultaneously fostering the synergy between scientific research and popularization.
Volume 70,2024 Issue 1
Scolarly discussion
通 讯 资 料 · 消 息 报 道 · 新 书 介 绍
Scolarly discussion
通 讯 资 料 · 消 息 报 道 · 新 书 介 绍
Scolarly discussion
Scientific review
Reserch progress
通 讯 资 料 · 消 息 报 道 · 新 书 介 绍
Reserch progress
通 讯 资 料 · 消 息 报 道 · 新 书 介 绍
Publish online-I
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Volume 70,2024 Issue 1
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Definition of the late Permian bimodal volcanic rocks in the Yanyuan area of Sichuan Province and its geological significance
Cheng Jiankang, Sun Baowei, Huo Jiaqing, Xiao Liang, Wang Bin, Zhu Kaining
Abstract:
Objectives:This paper focuses on the study of petrology and geochemistry of the newly discovered bimodal volcanic rock assemblage in Bailinshan area,Yanyuan,Sichuan,and discusses its petrogenesis and tectonic geological background,which provides new clues and geological basis for further research on the formation mechanism, tectonic evolution and mineralization of Emeishan large igneous province. Methods:On the basis of field investigation,representative samples of basic and acid volcanic rocks were collected,and the bimodal volcanic rocks were studied by microscopic observation,analysis of major elements,trace elements and rare earth elements,and the petrogenesis and tectonic environment of the bimodal volcanic rocks were discussed. Results:A bimodal volcanic rock composed of alkali-rich high-titanium basalt and pantellerite was newly discovered in the Bailinshan area of Yanyuan County.It belongs to a part of the Emeishan large igneous province and was formed in the late Permian.Both basalt and pantellerite are characterized by light rare earth enrichment.The rare earth content and fractionation degree in pantellerite are significantly higher than those in basalt,and pantellerite shows obvious negative Eu anomaly.The basalts are relatively enriched in high field strength elements such as U,Th,Nb and Ta, and relatively depleted in large ion lithophile elements such as Rb,K and Sr.The pantellerite are significantly enriched in high field strength elements such as U,Th,Nb,Ta,Zr and Hf, and severely depleted in Ba,K,Sr,P,Ti,Ni and Cr.Basalt is the product of partial melting of mantle peridotite to a small extent.Pantellerite is mainly formed by acidic residual magma after extreme separation and crystallization of basaltic magma.The basalt were formed in the oceanic island environment,and the pantellerite were formed in the intracontinental extensional environment.The tectonic environment is related to the activity of the Emeishan mantle plume and the intracontinental rift extension by it. Conclusions:The definition of the late Permian bimodal volcanic rocks in the Bailinshan area is of great significance for the study of regional tectonic evolution and mineralization and the expansion of prospecting ideas.
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Study on the Impact of Deep and Large Shaped Foundation Pit Construction on Adjacent Very Large Bridges and Deformation Control in the Diffuse Beach Area of the Yangtze River
SHI Jiansheng, XU Yuan, LI Hui, YAN Changhong, HOU Jue, YU Liangchen, ZHAO Huaxin, CUI Wanghong, Xu Chenghua, Liu Gang
Abstract:
With the development and utilization of underground space resources, more and more deep foundation pits present the characteristics of deep excavation, large scale, irregular shape, etc., and their supporting structure design is complicated and construction is difficult, with obvious spatial effects. This paper takes a pit project of Nanjing subway as an example to analyze the impact of pit construction on neighboring bridges. The site is located in the lower reaches of the Yangtze River diffuse phase binary structure stratigraphy distribution section, the upper soft soil layer thickness is large, the lower pressurized aquifer water table is high, rich in water, geological conditions are very complex, the pit is a typical deep and large heterogeneous pit, away from the hyperbolic arch approach bridge is only 7.2 m, due to the bridge has been subjected to other underground engineering construction produced by a large deformation, the deformation that can be withstood is close to the critical value, so the subsequent project on the neighboring bridge. For this reason, the station pit support structure design based on the actual function of the underground space by setting partition wall partition excavation and MJS ultra-deep method wall comprehensive deformation control program. In this paper, by taking finite element numerical simulation to carry out the deformation prediction analysis of enclosure structure and bridge pile foundation caused by pit excavation in complex environment, the calculation results show that this deep, narrow and long shaped pit excavation has significant effect on settlement deformation of neighboring bridges, and the deformation control through the setup of partition wall subdividing excavation and MJS method wall can control the spatial effect of the pit and reduce the "long side effect", " heteromorphic effect" and other effects on the bridge settlement deformation. The feasibility of this comprehensive deformation control program is verified through the actual monitoring results of the on-site foundation pit excavation process. The research results are of good reference significance for the support and construction design of deep, narrow and long shaped foundation pits under similar complex geological conditions.
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The Miocene adakitic rocks in the Reskam area, SE Pamir: Implications for the Cenozoic tectonic evolution
MUREDILI Mahemuti, LIU Xiaoqiang, ZHANG Chuanlin, YANG Zhihao, HE Chao
Abstract:
Post-collisional magmatism is one of the key objects for exploring the composition of lithosphere and retrieving the deep geodynamic processes. Recently, our research group identified a new set of Cenozoic adakitic intrusive rocks in the Reskam area, southeast Pamir. In this paper, we report zircon U-Pb ages, whole-rock major and trace elements, whole-rock Sr-Nd and zircon Lu-Hf isotope compositions of these adakitic rocks. Zircon LA-MC-ICPMS U-Pb dating results show that these magmatic rocks were emplaced at Miocene (12.0 ± 0.3 Ma). Geochemically, they have high SiO2 (72.14% ~ 74.35%) and high K2O (3.78% ~ 5.25%) contents, with low MgO (0.13% ~ 0.50%) and Mg# value (18 ~ 35). They exhibit high Sr (363-754 ppm), low Y (3.41-16.4 ppm) and Yb (0.327 ~ 0.903 ppm), thus high Sr/Y (27 ~ 188) and (La/Yb)N (18.95 ~ 210) ratios, in keeping with the typical adakites. In terms of isotopes, they have significantly enriched in situ zircon εHf(t) (-10.1 ~ -5.4) and whole-rock εNd(t) (-8.33 ~ -6.39) values. In combination of the data in this study and the published references, the Reskam Miocene adakitic rocks were most likely originated by partial melting of thickened lower crust as a result of India-Asian collision. We suggest that collapse of the local thickened lithosphere due to gravitational instability, and the upwelling of the asthenosphere caused partial melting of the thickened old lower crust, forming the Miocene adakitic magma.
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Geochronology and geochemistry of the Liangtou pluton in northern Hebei:implications for the Paleo—Asian Ocean closure
WANG Jinfang, LIU Chenyu, LU Zeqian, LI Kangshuo, SONG Yutong, LI Yingjie, CHEN Gongzheng, DONG Peipei, YANG Fei, LI Hongyang
Abstract:
The closure time of the Paleo—Asian Ocean(PAO) on the northern margin of North China Plate is still unclear. The Liangtou monzogranite in Zhangbei area of northern Hebei Province is located in the central part of the northern margin of the North China Craton(NCC),which is bounded by the southeastern margin of the PAO tectonic region, and has important implications for the PAO closure.This paper present results of petrology,geochemistry,LA-ICP-MS zircon U-Pb geochronology and Hf isotopic composition of the Liangtou pluton to discusse the petrogenesis and tectonic setting．The zircon U-Pb LA-ICP-MS dating shows that the age of the adakitic rocks is 262.5±2.6Ma, indicating that the pluton was emplaced in the Late Permian. Petrological and petrogeochemical studies show that the rock has higher SiO2 (70.27% ~ 73.89%),Na2O (4.2% ~ 4.55%),K2O (3.87% ~ 4.64%),Sr (417.00×10-6 ~ 827.00×10-6),and lower Yb (0.29×10-6 ~ 0.52×10-6),Y (2.74×10-6 ~ 6.98×10-6) contents. It is enriched in Sr and other large ion lithophile elements and LREE, depleted in Ti, P, Nb, Ta and other high field strength elements and HREE, with intense fractionation between LREE and HREE ((La/Yb)N=15.55 ~ 67.31) and weak positive Eu anomaly. All of the geochemical characteristics indicate that the Liangtou pluton belongs to adakitic rocks and arc magmatite formed in the active continental margin arc setting along a ocean—continent zone.TheSzircon εHf (t) values range from -17.50 to -11.12, with two-stage model ages (tDM2) of 1989Ma ~ 2390Ma.Combined with the study of spatio—temporal evloution of the Late Carboniferous—Early Permian arc magmatic rocks in the northern margin of the NCC,it is assumed thatSLiangtou monzogranite occurred on the northern margin of NCC indicate that the PAO may still be in the process of subduction towards the northern margin of the NCC during the Late Permian(262.5±2.6Ma), and its final closure time may have been at the end of the Late Permian.
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The occurrence status and genesis of the Jinyinshan lithium deposit in Chibi, Hubei
yinjin, wujinhao, liyuan, wangjian, zhongwen, zengtengfei, yangrong
Abstract:
The Jinyinshan lithium deposit is located in Chibi City, Hubei Province. The ore-bearing lithology is mainly silicified cataclasite, cataclastic silty slate, cataclastic argillaceous slate, grayish-white metamorphic Siltstone, and lamprophyre. It has been reported that the cookeite is found in the cataclastic silty slate in this area, However, there is a lack of research on the form of lithium in all ore-bearing lithology, especially in lamprophyre. The article selected all ore-bearing lithology in the area for scanning electron microscopy analysis, and it is believed that there are no mica minerals in this area. In situ X-ray diffraction (XRD) study was carried out and the characteristic peak of cookeite was found. In situ trace element analysis (LA-ICPMS) and other analyses have been carried out. It is found that Li and Al2O3 have a strong positive correlation, which confirms that lithium in this area exists in the form of cookeite. In addition, cookeite in this area is mainly filled between quartz grains or in olivine pseudocrystals, and its occurrence is scaly and bamboo leaves, It is completely consistent with the genetic characteristics of the hydrothermal cookeite, so it is inferred that cookeite in Jinyinshan mining area is of hydrothermal origin. As the Mufu Mountains complex rock body, which is closely related to rare metal mineralization, is about 15km away from the south, the ore-forming materials may come from the southern rock body,In the subsequent process of mineral exploration, attention should be paid to searching for similar lithium deposits between the F9 fault and the rock mass.
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Study on the typical water storage structure model of Jiaodong Peninsula under the influence of human activities
chenjingpeng, kangfenxin, hanjianjiang, jiangshujie, wangmingzhu, wangweilong, duanxiaofei
Abstract:
Objectives:Jiaodong Peninsula is a typical water-scarce mountainous area in China, where magmatic rocks, metamorphic rocks and chalk impervious sandstones are widely distributed, and aquifers differ greatly in water richness. Meanwhile, there are intensive human activities in Jiaodong Peninsula, and the problem of poor water quality caused by poor water quality is also prominent, and resource-based water shortage and water quality poor water shortage problems exist simultaneously，In order to reveal the water storage structural model and water seeking direction of typical water-scarce mountainous areas under the influence of human activities. Methods:the hydrogeological survey conducted in the typical water-scarce mountainous areas of Jiaodong Peninsula from 2019 to 2022, using 7 groups of borehole data , 7 groups of hydrochemical and isotope analysis samples from this construction, based on the theory of water storage structure and combined with the water chemical and isotope characteristics under the influence of human activities, the water richness of different types of water storage structures and the influence of human activities represented by nitrate on water quality were compared. Results:In this paper, the structure of the water storage structure of the depression, the contact band, the fracture and the karst type are summarized.It is revealed that the nitrate content of the weathered fissure water represented by the weathered water storage structure in the depression and gully is increased and the water quality is poor due to human activities ,It also revealed that the water is susceptible to human activity, the nitrate content is raised, the water quality is poor, the complete bedrom of the confined water layer is the influence of human activity on the groundwater, the low nitrate content and the water quality.The upper intact bedrock of structural fissure water (confined water) represented by fault-type water storage structure acts as a water barrier covering layer, which weakens the influence of human activities on groundwater, and has low nitrate content and good water quality. Conclusions:The fault-type water storage structure-confined water is suitable for urban and rural domestic water, while the weathered water storage structure-weathered fissure water in depressions and valleys is suitable for industrial and agricultural production. The development and utilization direction of contact zone type and karst type water storage structure is related to the buried depth of aquifer.
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Stratigraphic Division and Tectonic Background of the Jiangxian Group in the Zhongtiao Mountain of the Trans-North China Orogen, North China Craton
Abstract:
The Zhongtiao Mountain, an important part of the Trans-North China Orogen, North China Craton, holds well preserved significant evolution records of the Trans-North China Orogen. The Jiangxian Group is divided into the Henglingguan Subgroup and the Tongkuangyu Subgroup, the Henglingguan Subgroup consists predominantly of metamorphic clastic rocks, specifically quartzite and phyllite. In contrast, the Tongkuangyu Subgroup primarily comprises acid and basic volcanic rocks, with “bimodal” volcanic rocks alternating with normal sedimentary clastic rocks. Based on field investigation on the rock composition and stratigraphic characteristics and comprehensive analysis of zircon isotopic ages of the volcanic rocks, intrusive rocks, and detrital zircon of the Jiangxian Group, the age for this Group is estimated to be around 2200 Ma to 2120 Ma, corresponding to the Paleoproterozoic era. By integrating the geochemical characteristics of clastic and volcanic rocks with the evolutionary history of the Trans-North China Orogen, it is inferred that the Jiangxian Group likely originated in a tectonic environment linked to a paleo-active continental margin. Specifically, the Henglingguan Subgroup was deposited in an active continental margin basin, whereas the Tongkuangyu Subgroup originated in a volcanic arc of an active continental margin.
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Geological and Geochemical Characteristics of Volcanic rocks of Baiyingaolao Formation, Sanjie Aobao, Inner Mongolia
Liujingjing, Liyingjie, Lnmin, Dongpeipei, Zhaodongfang, Chenxianting, Liuzhibin
Abstract:
Based on the 1:50000 regional geological survey and the triple mapping method of "volcanic tectonic-lithologic lithofacies-volcanic stratigraphy", the volcanic rocks of the Baiyingaolao Formation in Sangjie Aobao area, East Wuqi, Inner Mongolia, are divided into three lithologic segments, namely, pyroclastic sedimentary rocks, acid volcanic rocks and neutral volcanic rocks, which constitute a complete sediment-eruption cycle. The magma evolved from acidic to neutral from early to late period. Volcanic sedimentary facies, cave-down accumulation facies, overflow facies and volcanic channels were developed, and six V-class volcanic structures were delineated. Based on LA-ICP-MS zircon U-Pb isotope dating, it is determined that the second member rhyolite of Baiyingaolao Formation in Sanjie Aobo was formed in 134.95±0.99 Ma, and the age is Early Cretaceous. Geochemical characteristics show that the main element SiO2 content ranges from 69.56% to 71.11%, K2O content ranges from 3.96% to 4.39%, K2O/Na2O value ranges from 0.69 to 1.03, and A/CNK value ranges from 0.97 to 1.07. The volcanic rocks of Baiyingaoao Formation in Sanjie Aobo belong to the high potassium calc-alkaline series. Rb, K, Th, U are relatively enriched, Sr, Ti, Nb, Ta, P are relatively depleted, and the difference of heavy and heavy rare earths is obvious, and the former is higher than the latter, and the standardized partition curve of rare earth elements chondrites shows A right-leaning "seagull", which conforms to the geochemical characteristics of A-type granite. Combined with previous studies and data analysis, the volcanic rocks of Baiyingaolao formation in Sanjie Aobao should be formed in the post-orogenic extensional tectonic environment. Therefore, the determination of the volcanic rocks of the Baiyin Gaolao Formation in this study area provides petrological, chronological and geochemical constraints on the stratigraphic sequence and tectonic setting of the Mesozoic volcanic rocks in the eastern part of the Central Asian orogenic belt.
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Background of the South-North Water Transfer Project: Response and regulating factors of groundwater recharge to surface deformation in the middle and upper regions of the Chaobai River alluvial fan
Abstract:
Continuous groundwater recharge was crucial in preventing and reducing the development of land subsidence once southern water entered Beijing in 2014. However, it is still unclear how groundwater rebound and its governing elements produce ground sinking and rebound in various places and strata. Understanding the mechanism of surface deformation, identifying the primary limiting factors for future scientific replenishment, maximizing the benefits of water resource replenishment, preventing land subsidence, and managing overexploited areas are all very important. Deep exploration and study of these relationships is also very important. This paper uses persistent scatterer interferometric synthetic aperture radar (PS-InSAR) technology, along with regional stratified groundwater level dynamic change, stratified settlement change, and other means to carry out coupling, to obtain information on ground subsidence and deformation in the study area. The intention is to determine which response and control factors between the surface and subsurface processes. The findings indicate that (1) the region"s land subsidence is slowed down by the south water"s constant replenishment, and that the Niulan Mountain region experiences surface uplift. With the rise in water level, the uplift area also gradually widens to the middle and downstream, and the maximum rebound rate reaches 46.9mm/a in 2022. (2) The Houshayu depression, which is split by the Huangzhuang-Gorliying fault, Shunyi fault, and Nankou-Sunhe fault, has undergone more alterations than other regions because for any particular characteristics of Quaternary depositional differences governed by faults. (3) The range and responsiveness of water level rise are determined by variability in groundwater level amplitude and water richness, and the direction of groundwater flow is somewhat controlled by quaternary sedimentary differences brought on by sedimentary tectonics. The findings also offer a theoretical and scientific foundation for study on mechanisms, prevention, and control of land subsidence, as well as direction and a point of reference for groundwater cleanup and program optimization that will come later.
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Thoughts on Strengthening the Overall Storage of Physical Geological Data in China
Abstract:
Physical geological data is a valuable resource formed by geological exploration work. Ensuring the safe and proper storage of important physical geological data is an important guarantee for achieving effective preservation and efficient utilization of their potential value. However, how to improve the contradiction between the growing demand for important core storage and limited warehouse construction is an urgent issue facing the current work of physical geological data storage in China. The paper systematically summarizes the important achievements made in the system construction and warehouse construction of physical geological data storage in China in recent years, analyzes the main problems currently faced, and studies and proposes suggestions on the overall layout and mechanism construction of physical geological data storage in China, providing reference for improving the overall storage capacity of physical geological data in China.
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Sediment provenance and source-to-sink coupling of the late Eocene Fushan Sag in Beibuwan Basin
Liao Feiyan, Shi Yang, Zhang Yuanze, Lu Zhenghuan, Guo Hao, Li Xiaohan
Abstract:
The Paleogene Fushan Sag is characterized by small area, multiple sources as well as complex and variable depositional systems, and the source-to-sink relationship and coupling are poorly understood. By multiple methods of seismic foreset reflection, zircon U-Pb dating, heavy mineral assemblage and distribution of sandstone percentage, the provenance of upper submember of the first member in Liushagang Formation was investigated to determine the source-to-sink relationship, and then different source-to-sink coupling models of the late Eocene Fushan Sag were established to guide favorable reservoir prediction. The results show that the seismic profiles from southern gentle slope, western steep slope and eastern steep slope zones exhibit obvious foreset reflection; similar to those from Hainan Island, the zircon U-Pb age spectra of Yongan and Huachang areas are characterized by double peak ages; the heavy mineral assemblages of Fushan Sag can be classified into four categories, i.e., Chaoyang area in the western steep slope zone, Jinfeng area in the eastern steep slope zone, Meitai and Yongan areas in the west side of the southern gentle slope zone, and Huachang and Bailian areas in the east side; the high percentage values of sandstone can be seen along Meitai, Huachang and Bailian areas in the southern gentle slope zone, which can be extended to Yongan area in the north, and the median percentage values of sandstone can be seen in Chaoyang area in the west and Jinfeng area in the east. Comprehensive analyses indicate that the late Eocene Fushan Sag had three major sources, i.e., Hainan Island in the south, Lingao Uplift in the west and Yunlong Uplift in the east, of which the source of Hainan Island can be divided into east and west branches. The late Eocene Fushan Sag is further divided into three secondary source-to-sink systems, including Hainan Island-southern gentle slope zone, Lingao Uplift- western steep slope zone and Yunlong Uplift-eastern steep slope zone. From the perspective of source-to-sink system, the underwater distributary channel in the source and sink system of Hainan Island-southern gentle slope zone is a favorable zone for high-quality reservoir development.
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First Discovery of Hipparion Fauna from the East Piedmont of the Taihang Mountains
Chen Shaokun, Quan Yongtao, Qi Haiyan, Zhang Tong, Pang Libo, Liu Aoran
Abstract:
Objectives: The uplift of the Taihang Mountains in the late Cenozoic signals the primary formation of modern landforms in North China, but there are still many different opinions on its development. Paleontological evidence can play an essential role in the study of the uplift of the Taihang Mountains. Methods: The newly discovered Jingxing Hipparion fauna was excavated from the alluvial-fluvial fan on the Tangxian planation surface at the east piedmont of the Taihang Mountains, including Felidae gen. et sp. indet., Hyaenidae gen. et sp. indet., Dihoplus ringstroemi, Sivalhippus platyodus, Propotamochoerus sp., Chleuastochoerus sp., Schansitherium sp., Palaeotragus sp., Dorcadoryx sp., Gazella gaozhuangensis and G. cf. gaudryi. Results: The Hipparion fauna was discovered firstly in the east piedmont of the Taihang Mountains. Biochronological observation of this fauna implies an age of latest Miocene to earliest Pliocene (about 6.0-5.2 Ma) or late MN 13, correlated to Taoyang member of Gaozhuang Formation in the Yueshe Basin of Shanxi Province. Conclusions: Since the fauna was excavated from the redclay on the Tangxian planation surface, it is concluded that the uplift of this surface was not earlier than Early Pliocene. Additionally, the fauna composition indicates an open forest and grassland environment which is entirely different from nowadays.
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The discovery of terrigenous siliciclastic rocks and its significance of the Lower Permian Qixia Formation in northern Sichuan Basin
ZHANG Pengfei), LI Fengjie), LI Zhiwu), wangjia, SONG Jinmin), chenzhenan, YE Yuehao), CHEN zheng''an), zhangxihua, WANG Jia), yeyuehao
Abstract:
Terrigenous siliciclastic deposits have been found in the Lower Permian Qixia Formation marine carbonate strata at the Shuanghui section, Wangcang County, northern Sichuan Basin. The provenance and depositional environment of the terrigenous siliciclastic rocks are analyzed through field section observation, sedimentology, petrology and zircon U-Pb chronology methods. On this basis, the paleogeographic pattern of the study area are reconstructed. The results show that the siliciclastic rocks has typical coastal-tidal flat depositional characteristics, which reflects that the study area experienced a transient sea level drop and exposure in the Early Qixia Stage. The morphologies of detrital zircons in sandstone indicate that they have experienced long distance transport or recycle deposition, and the U-Pb ages of zircons are mainly concentrated in the four age ranges of 2600–2400 Ma, 1800–1200 Ma, 1000–700 Ma and 500?400 Ma. Compared with the Zircon U-Pb age spectrums of the Permian, Devonian, Silurian and Precambrian strata and intrusive rocks around the Yangtze block, and integrated regional tectono-sedimentary evolution, we propose that the Siluran-Devonian strata is the possible source of the Permian siliciclastic rocks. The zircon age frequency spectrum of the Qixia Formation siliciclastic rocks is very similar to those of Liangshan Formation, which indicates that the Liangshan Formation is probably the direct material source of the siliciclastic rocks. The occurrence of siliciclastic rocks indicates that there existed short-lived island or old land in the local area of the northern Upper Yangtze, which provided a favorable depositional environment and source supply for the formation of siliciclastic rocks. Based on the sedimentary characteristics and provenance analysis of the siliciclastic rocks, a multi-stage Early Permian paleogeographic evolution model in the northern Sichuan Basin is established. The discovery of the terrigenous siliciclastic rocks of the Qixia Formation is of great significance for the deep understanding of the Early Permian paleogeographic pattern, tectono-sedimentary evolution and hydrocarbon exploration in the northern Upper Yangtze region.
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Geological and chronological characteristics of the Manitu Formation in Chabuqiri， Inner Mongolia
CHEN Xian-ting, LI Ying-jie, LIN Ming, DONG Pei-pei, ZHAO Dong-fang, LIU Jing-jing, LIU Zhi-bin
Abstract:
Based on 1/50,000 regional geological survey, the field geological characteristics, petrology, geochemistry and zircon U-Pb chronology of the volcanic rocks of the Manitu Formation in Chabuqiri area, Inner Mongolia were systematically studied by using the triple mapping method of "volcanic structural-lithofacies-volcanic stratigraphy", and the formation age, petrogenesis and regional tectonic background of the volcanic rocks of the Manitu Formation were analyzed.The Manitu Formation in Chabuqiri area of Inner Mongolia is divided into two lithologic segments, one consisting of pyroclastic sedimentary rocks and the other of neutral volcanic rocks, which constitute a complete sedimentation-eruption cycle. The volcanic facies are divided into eruption-sedimentary facies, exhalation facies, clastic flow accumulation facies, cave-fall accumulation facies and volcanic passages. Circle four V-class volcanic institutions; The LA?ICP?MS zircon U?Pb age of the andesite of the second member of the Chabuqiri manitu Formation is 157.8±1.4Ma, indicating that the formation age of the andesite is Late Jurassic.
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Zircon SHRIMP U-Pb Ages and Hf Isotope Characterestics and Their Geological Significance of Tuff in Ordovician Majiagou Formation in the Middle-eastern Ordos Basin
Abstract:
The Upper Member of the Ordovician Majiagou Formation (referred to as the "M5" member) in the Ordos Basin is characterized by the presence of two layers of tuffs, which are commonly used as regional marker beds for stratigraphic correlation. Investigation of the zircon ages of these tuffs can help establish the chronostratigraphic framework of the Majiagou Formation and provide insights into its depositional period and tectonic background. Zircon SHRIMP U-Pb dating and Hf isotope analysis were conducted on tuffs from wells S148 and T56 in the M5 member of the basin. The obtained zircon ages of these two samples are 458.4±2.4 Ma and 460.9±2.9 Ma, respectively. Based on these results, the deposition of the Majiagou Formation is constrained to the Middle Ordovician Darriwilian to Upper Ordovician Sandbian stages. The measured n(176Hf)/n(177Hf) ratios of in-situ zircon Hf isotopes range from 0.282687 to 0.280820, and εHf(t) values vary from +6.67 to +11.32, with two-stage model ages ranging from 720 to 1024 Ma. Comparison of the zircon U-Pb ages and Hf isotope characteristics of the tuffs surrounding the basin suggests that the volcanic tuffs of the Majiagou Formation may have originated from the North Qinling and/or North Qilian orogenic belts in the southwestern part of the basin. Furthermore, it is inferred that prior to the emplacement of the tuffs, the North Qinling and/or North Qilian Ocean initiated a northward subduction and entered a stage of ocean-land transition, indicating the transformation of the western and southern margins of the basin into an active continental margin during the Late Middle Ordovician.
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Geochemical characteristics of Lower Cretaceous in Zhenyuan area of Ordos Basin and its indication to provenance and tectonic setting
HE Zhongbo, HU Baoqun, JI Huali, HE Feng, GENG Yingying, HUANG Shaohua, ZHU Manhuai
Abstract:
Based on the geochemical analysis of major elements, trace elements and rare earth elements（REE）of the Lower Cretaceous sandstone in Zhenyuan area of Ordos Basin, this paper discusses the sedimentary recycling characteristics, chemical weathering, tectonic background and material source of the Lower Cretaceous red variegated sandstone. The results show，（1）The Lower Cretaceous Luohe Formation, Huanhe Formation and Luohandong Formation are similar in provenance main body, and have good inheritance in structural background, provenance area and provenance characteristics. The provenance area is generally characterized by rich quartz, rich Calcite cement, more potassium feldspar or potassium rich minerals than plagioclase. The Luohandong Formation is more siliceous than Huanhe Formation and Luohe Formation, with less Calcite cement and purer quality. The REE distribution pattern curves of rare earth elements are consistent, with clear fractionation of light and heavy rare earth elements, enriched in large ion lithophile elements Ba, Pb, Sr, and light rare earth elements, and depleted in high field strength elements Nb, Ta, Th, Y, etc. From bottom to top, with the formation becoming newer, the total REE content in Sedimentary rock tends to decrease, and the fractionation degree of heavy REE decreases.（2）The original material of the Lower Cretaceous sandstone in the study area is mainly composed of felsic and mafic mixed rocks（such as intermediate-acid intrusive rocks, felsic metamorphic rocks）and some sedimentary rocks. Most of the sediments in the study area are transported by the weathering and denudation products of the parent rock in the thrust nappe zone on the southestern margin of the Ordos Basin, Which are the first sedimentary materials. A few sediments ( i.e., Aeolian sand) are formed by in-situ re-transport and accumulation, which are recycled sedimentary materials. （3）In the tectonic setting, the passive continental margin tectonic environment is the main advantage. The debris mainly comes from the continental source area, followed by the recycled orogenic belt and the mixed source area.
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Sedimentary Characteristics of Lower Cretaceous in Wuerhe-Huanghuagou area, northwestern margin of Junggar Basin
JI Huli, HE Zhongbo, ZHONG Jun, CHEN Hong, ZHU Bin, WU Yu, DONG Qian, GENG Yingying
Abstract:
Based on the comprehensive analysis of outcrops, drilling cores, drilling and logging in the Wuerhe-Huanghuagou area on the northwestern margin of the Junggar Basin, combined with microscopic observation, the main petrological characteristics, stratigraphic structure, sedimentary facies types and distribution characteristics of the Lower Cretaceous Tugulu Group were comprehensively analyzed. Guided by the metallogenic theory of sandstone-type uranium deposits, the types and distribution of favorable ore-forming sand bodies in the Lower Cretaceous Tugulu Group in the study area were discussed from the perspective of sedimentology. The results showed：(1)The rock types of the Lower Cretaceous Tugulu a sub-group in the study area are mainly feldspar lithic sandstone and lithic feldspar sandstone, while the Tugulu b, c and d sub-groups are mainly feldspar sandstone and feldspar lithic sandstone.(2)There are four types of sedimentary facies in the Lower Cretaceous Tugulu Group in the study area, which are alluvial fan, braided river, delta and lake. With the Delun Mt. as the boundary, the Wuerhe-Xiazijie area is dominated by shallow-water delta deposits with far-source weak current, while the Delun Mt.-Huanghuagou area is dominated by high-energy braided river deposits.(3)The favorable prospecting horizon of the Lower Cretaceous is the primary gray-gray green coarse clastic formation of the Tugulu a + b subgroup. The branch channel of delta plain subfacies in Wuerhe-Youshashan area is an important prospecting direction. The underwater distributary channel of delta front and the thick sand body of sheet sand widely developed in the Xiazijie area have good lateral extensibility, and have the structure of " mud-sand-mud ". Under the condition of sufficient supply of water source, uranium source and oxygen source, it has the ability to form a certain scale sandstone-type uranium deposit.
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Development Sequence, Formation Age and Geological Significance of Piedmont River terrace in Pinggu, Beijing
Wang Xiaoliang, Zhao Yuanyi, Zhao Xitao, Chen Jundian, Wu Wenbin
Abstract:
River terrace is a good carrier for the study of river evolution and tectonic movement. Although the Quaternary geology in Beijing area is highly studied, there are few relevant research data on river terrace in the east of Beijing. In this paper, Ju River, Huangsongyu River and Jiangjunguanshi River developed in front of Yanshan Mountain, are taken as the research objects in Pinggu Beijing. The development sequence of the above-mentioned river terraces is divided in detail. On this basis, the formation times, terrace genesis and the response of river terraces to the uplift of Yanshan Mountain are discussed by field geological survey and opto-luminescence dating (OSL). It is considered that Ju River developed three terraces on the south bank and developed two terraces on the north bank. Huangsongyushi River developed six terraces. Jiangjunguanshi River developed five terraces. Jiangjunguanshi River was formed at least in the late Middle Pleistocene (161.7±7.7 ka BP) and Huangsongyushi River was formed at least in the early late Pleistocene (121.2±5.4 ka BP~100.3±4.1 ka BP). Ju River was formed at least during the middle of the Late Pleistocene (79.4±3.3 ka BP to 70.8±3.4ka BP). The formation of the terraces of Ju River, Huangsongyu River and Junjiangguanshi River is influenced by paleoclimate change and Yanshan Mountains uplift. Yanshan Mountains in Pinggu area has been in a state of uplift since the late Middle Pleistocene, and the uplift rate reached the maximum in the early late Pleistocene, up to 0.24~0.34 mm/a, and decreased in the middle of the late Pleistocene. 0.18 to 0.24 mm/a. The above results have important reference value for the study of the development characteristics and formation times of river terraces in eastern Beijing, and also provide new evidence for the uplift of Yanshan Mountain since the late Middle Pleistocene.
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Geochemical characteristics of Wufeng-Longmaxi shales in the southern margin of the Upper Yangtze and their implications for weathering, provenance and tectonic setting
Qin He Xing, chen lei, lu chang, hu yue, xiong min, tan xiu cheng, ji yubing, chen xin, wang gao xiang
Abstract:
Objective: In order to further explore the material source, weathering and tectonic setting of the Late Ordovician-Early Silurian black shale in the southern margin of the Upper Yangtz, this study selected typical field section for systematic sampling, systematically studies the geochemical characteristics of major, trace and rare earth elements of Wufeng-Longmaxi Formation shale and discusses its geological significance. Methods: Through the characteristics of major, trace and rare earth elements of 22 samples of Wufeng-Longmaxi Formation shale in the field profile of the southern margin of the Upper Yangtze, the ancient weathering intensity and paleoclimate conditions were restored, the source rock properties and tectonic background were revealed, and the shale formation environment and process were explored, which provided more favorable geochemical evidence for further exploration and development of Wufeng-Longmaxi Formation shale in the Upper Yangtze region. Results: The black organic-rich shale of Wufeng-Longmaxi Formation in the southern margin of the Upper Yangtze has the characteristics of poor high field strength elements and enrichment of large ion lithophile elements similar to the upper crust. The ∑ REE value (103.66×10-6~295.98×10-6, average 180.57×10-6) is generally high. The standardized distribution pattern of rare earth elements is very similar to that of the upper crust, showing the characteristics of 'V' type to the right, enrichment of light rare earth elements, flat heavy rare earth elements, obvious differentiation of light and heavy rare earth elements, and obvious negative Eu anomaly. The contents and ratios of characteristic trace and rare earth elements, such as La, Ce, La/Yb and Sc/Cr, are close to the characteristic values of passive continental margin. The ICV values (0.55~14.1, average 2.28) and Zr/Sc- versus Th/Sc diagram indicate that the source is the first rapid sedimentary product of the tectonic belt, and does not have the characteristics of sedimentary recycling. The lower CIA value (54.89-71.61, average 65.27), A-CN-K diagram and K2O/Al2O3 versus Ga/Rb diagram indicated that the provenance was less affected by chemical weathering, and the sedimentary environment was cold and dry. The high contents of K2O, Rb, Al2O3/TiO2 and negative Eu anomaly indicate that the source rocks are dominated by felsic igneous rocks and acidic geological bodies of granites. Conclusion: Based on the discriminant diagram of provenance and tectonic background, it is inferred that the main body of Wufeng-Longmaxi Formation shale in the southern margin of Upper Yangtze is formed in the passive continental margin. The provenance mainly comes from the early Neoproterozoic platform caprock of Kangdian ancient land on the west side, followed by Qianzhong uplift, with the influx of intermediate-acid volcanic materials in the southeast of Yangtze plate.
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Characteristics of Ordovician paleokarst development and paleogeomorphic restoration in Shungeng mountain, Huainan
YANG Tingting, XU Guangquan, ZHANG Zhu, LI Hao, ZHANG Jinsheng, HE Biao
Abstract:
s: The characteristics of paleokarst development and the restoration of paleomorphology are important for preventing and controlling karst water damage in the North China Coalfield. This study focuses on the paleokarst of the Ordovician system in Shungeng Mountain, Huainan area, which is located at the southern edge of the North China plate. The characteristics of paleokarst development and the bedrock is undulating were revealed by field geological surveys, sectional profiling and residual thickness methods. Based on modern karst theory, the spatial variation patterns of different karst zones were analyzed from the perspective of their formation conditions, and the paleokarst landforms were restored. The results show that the Majiagou Formation has mainly large karst channels and holes with little internal filling, while the Xiaoxian Formation has mostly interlayer karst along the level, filled with karst breccias. The internal filling calcite increases from east to west. The Ordovician palaeokarsts in the Shungeng Mountains weaken gradually from east to west and from top to bottom. The Ordovician paleomorphology of the area is higher in the east and lower in the west and can be divided into four three-level karst geomorphic units: residual hills, gentle slopes, steep slopes and depressions. The paleokarst landscape from top to bottom was classified into superficial karst zone, vertical seepage zone, horizontal submerged flow zone and deep slow flow zone from shallow to deep, based on the karst geological conditions, groundwater runoff patterns and karst development characteristics. The superficial karst zones and vertical seepage zones of the residual hills and gentle slopes are the most developed, and large karst fissures often occur between the sedimentary layers, which may cause karst collapses when the groundwater flow changes.
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WANG Deyuan, Jean Bottazzi, ZHOU Wenlong, LI Wei, HU Wanmei, LYU Xiaoxi: Discovery and the significance of giant panda (Ailuropoda melanoleuca) fossils from the Yangtianwo Shaft in Huishui County, Guizhou Province
Wang Deyuan, Jean Bottazzi, Zhou Wenlong, Li Wei, Hu Wanmei, Lv Xiaoxi
Abstract:
Giant pandas were widely distributed in South China during the Late Pleistocene, with numerous fossils, but relatively few complete bone materials. This article reports the latest discovery of a complete skull fossil of a giant panda at the Yangtianwo shaft in Huishui, Guizhou. The special cave conditions provide favorable conditions for the preservation of fossils. According to the measured data, the teeth of Yangtianwo giant panda are slightly larger than those of the existing giant panda, and should belong to the Ailuropoda melanoleuca baconi. The AMS-14C dating results are 22887-22431 a BP, which is around the last glacial maximum. The discovery of the new material provides a rare empirical evidence to infer the distribution range, survival and evolution of giant pandas at the end of the late Pleistocene.
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Reviews of important elements in sedimentary minerals deposited around Yangtze block from Neoproterozoic to early Paleozoic and their relationship to old ocean
ZHANG Yan, FANG Weixuan, CHEN Wen
Abstract:
Objectives: Redox Sensitive Trace Metals and Bio-essential elements can deposit and formed special sedimentary mineral deposits in special sedimentary setting. Deep understanding the important elements geochemistry, relevant sedimentary mineral deposits and their spatial and temporal distribution characteristic, can improve our cognition between the old ocean evolution and sedimentary mineral deposits formation. Methods: In this paper, we reviewed relevant elements migrate and concentrated regulation, and redox discrimination methods which included pyrite morphology, and biological productivity and basin limitation discrimination methods. Then we centralized summarized Nanhuan to early Silurian sedimentary Mn, P, Ni-Mo-Co, V and U mineral deposit around Yangtze block in genetic, distribution and the relation to lithofacies palaeogeography, under the background of global oxidation envent, glacial-interglacial envents, Rodinia supercontinent break up envent, metallogenic metal elements in the ocean accumulated during a long geology history. Results and Conclusions: So the sedimentary minerals in Yangtze block margin from Neoproterozoic to early Paleozoic is the natural laboratory to (1) research Redox Sensitive Trace Metals and Bio-essential elements action in different sedimentary environment, and (2) metallogenic mechanism and the contribution of seawater-biology-hydrothermal fluid end members. At last, to solve the problems in sedimentary ore deposits study of Yangtze block, we proposed solutions and future prospecting.
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Modern piedmont sediments of the Altyn Tagh in northern margin of the Qinghai-Tibet Plateau: Petrological research of lithic fragment in the Kumtagh Desert
JIN Bingfu, wubo, zhang yunji, yu jian, HASI Eerdun, Su Zhizhu, KONG Deyong, LI Xiubin, wu
Abstract:
The Gobi, platform, terrace, flat sand land on the edge of the Kumtagh Desert, as well as the interdune and gravel bodies inside the desert are rich in gravel of different sizes. The feathery flowing dune in the central and northern part of the desert core contains more coarse sand, which is rock debris rather than mineral debris. As a temporary intermediate product of weathering of parent rock, lithic fragments are the most reliable and direct indicator of the nature and origin of parent rock. In this study, the coarse grained rock deposits in the Kumtagh Desert were quantitatively analyzed by using the lithology microscopic identification and statistical methods of sand flakes for the first time of the desert research history. The results show that the types of fine gravel and coarse sand rocks in the Kumtagh Desert are very complex, including three rock classes(igneous rock, metamorphic rock and sedimentary rock), 14 rock classes and more than 100 subclasses, which are mainly middle-acid effusive rocks and regional metamorphic rocks. The most common lithologies are rhyolite, felsite, andesite, trachyte, quartzite and quartzitic rock. The lithology of dark particles is mainly middle-acid effusive rocks, while the lithology of light particles is metamorphic rocks and felsic minerals. The quartz fragments have both light and dark colors, which reflects the diversity of genesis and sources. The lithology of the debris is closely related to the grain size of the sand, the grain size of the sand is coarse, the lithology of the rock debris is relatively common with large mineral grains, while the content of the rock debris with fine grain size and the lithology of the parent rock with small mineral grains will increase, and at the same time, the content of single mineral in the sand will increase exponentially. This law makes different regions and different geomorphic locations of the desert, because of the different grain size of the sand. Regional differences of lithology distribution appear. The lithology in the desert is almost exactly the same as the lithology in the Altyn Tagh Mountain. The desert contains not only the common dynamic metamorphic rocks in the Altyn Tagh Mountain, but also various rock types of the ophiolite hybrid series unique to the Hongliugou - Lapaiquan member of the Altyn Tagh Mountain, which fully indicates that the gravel and coarse sand in the Kumtagh Desert come from the weathering of the parent rock of the Altyn Tagh Mountain. The difference of weathering of parent rocks and the different historical stages of mountain uplift make the content of lithology in desert different from that of mountain parent rocks. The cryptocrystalline and fine crystalline rocks resistant to weathering become the main characters of desert sand debris. The granitic rocks and mid-deep metamorphic rocks with coarse grained (crystalline) structure are easier to be decomposed into single minerals and are the main material sources of desert fine sand.
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Multiple phases of continental crustal growth of the basement of the Yanliao intracontinental rift: Constraint on the detrital zircon U-Pb-Hf isotopes of the sediments of Changcheng Group
LiWenqi, Liu Huichuan, Liu Xiaoping, Yu Zhiqi, Wang Yiren, Wang Yingying
Abstract:
The continental crustal growth of the North China Craton has been extensively studied. However, there has been limited discussions regarding the crustal growth of the Yanshan-Liaoning Rift Basin, which is covered by thick sediments. In this study, we focuse on sedimentary rocks of the Changcheng Group overling the Yanliao intracontinental rift and investigate scientific issues such as sedimentary age, provenance of detrital zircons and crustal growth events by analyzing the age spectrum and Lu-Hf isotope data of detrital zircons of the sediments within the Changcheng Group of the Yanliao intracontinental rift. U-Pb isotopic ages constrain the timing of initiation of the Yanliao rift as ca. 1680 Ma. The zircon U-Pb data show two major age populations at 2.7–2.5 Ga and 2.2–1.9 Ga, with high and positive eHf(t) values of + 0.1 to + 34.6. By comparing the U-Pb dating, Lu-Hf isotope εHf(t) and TDM2 model age data of detrital zircons from the Changcheng Group with those of the crystalline basement in the North China Craton, it can be inferred that the sedimentary source of the Changcheng Sediments in the Yanliao intracontinental rift originated from the underlying basement of the Yanliao intracontinental rift. Based on the comprehensive analysis of detrital zircon U-Pb dating, εHf(t) values, and TDM2 model age data, it is suggested that the North China Craton experienced three peaks in its Mesoproterozoic pre-crustal growth history, which occurred at approximately 2.7–2.5 Ga, 2.2–1.9 Ga and 1.7–1.6 Ga.
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Review on short polarity reversal events during the Cretaceous Normal Superchron
Abstract:
The Cretaceous Quiet Zone, also known as the Cretaceous Normal Superchron (CNS, 121.4~83.6 Myr), represents the most extreme geomagnetic field behavior in the geological history. Study of the characteristics of the geomagnetic field during the CNS is of great significance for understanding the abnormal changes of the physical and chemical processes in the Earth’s interior, such as the movement of the outer core fluid, the heat flux regime across the core-mantle boundary and patterns of mantle convection. Therefore, this paper systematically reviewed and summarized the previous research work related to short reversed-polarity events during CNS from the perspective of polarity reversal. The following main conclusions and views are obtained: the marine sediments, volcanic rocks and terrestrial sediments together indicates that at least seven reported reversed-polarity events or clusters of events might have happened within the CNS, including the Middle-Late Aptian (M“-1r” or “ISEA”), Late Aptian-Early Albian (~113.3 Myr), Middle Albian (M“-2r” set?), Late Albian (M“-3r” set?), Late Cenomanian (~96 Myr), Late Turonian and Late Coniacian-Early Santonian, which presents global synchroneity and a periodicity of 4~6 Myr. However, given the problems and uncertainties in paleomagnetic sampling and measurement methods, stratigraphic dating, possible remagnetization and rock magnetic analysis, the authenticity of polarity reversal events during the CNS and their occurrence time, frequency and duration are still controversial. Meanwhile, the short reversed-polarity events as a new constraint condition for the numerical simulation of the geodynamo can contribute to more scientifically revealing the unique dynamic change process in the Earth’s interior during the CNS and the internal genetic relationship with the global geologic events in the mid-Cretaceous. In the future, the integrated high-resolution magnetostratigraphic and geochronologic researches in the Cretaceous long-term scale, as well as the fine rock magnetic analyses of the reversed-polarity zones, is the key to accurately constrain the occurrence regularity of short polarity reversal events during the CNS.
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WAN Sheng 1), LIU Junping 2,3,4), SUN Chao 1), ZHAO Jiangtai 3), HE Shijun 5), YANG Shipan 3), ZHANG Kun 3)
Abstract:
Objectives: Through 1 ∶ 50000 regional Geological survey and typical section study, a set of abnormal enrichment layers of Nb, Co, Ga, Zr and REE with thickness of about 20~50 m has been identified at the top of Permian Mount Emei Formation in Luquan area, central Yunnan. Results:The main lithology of the enrichment layer is grayish purple mudstone, tuffaceous mudstone, Tuff, and partially mixed with almond basalt. Through groove analysis of enriched layers in the Luquan Wanlubu and Sajiaohai areas, it is shown that the Nb2O5 content ranges from 82.4 to 120.1 × 10-6, with an average value of 100.3 × 10-6, greater than the general industrial index of weathered crust type deposits 80 × 10-6; Ga content 28 8-35.6 × 10-6, with an average value of 32.1 × 10-6, higher than the current industrial indicator requirements for Ga mineral resources by 30 × 10-6; REE content ranges from 360 to 510 × 10-6, with an average value of 440.6 × 10-6, close to the general industrial index of weathered crust type deposits 500 × 10-6; The content of key metals in mudstone → tuffaceous mudstone → Tuff increases in sequence, which is positively related to the content of Volcanic ash. Weathering of Mount Emei basalt may result in the enrichment of key metals; Simultaneously enriched layers are accompanied by key metal mineralization phenomena such as Co, Zr, and Li. Conclusions: Therefore, the Permian Mount Emei Formation red top layer is an enrichment layer of key metals. In view of the wide distribution of the Permian Mount Emei Formation in central Yunnan, it is an area with rich prospecting prospects for Nb, Ga, Co, Zr, REE and other key metals, which deserves the attention of prospecting workers. The discovery of Pyroclastic rock Sedimentary rock interlayer and asphalt amygdala enriched with key metals among the basalts of each section of the Mount Emei Formation has proved that Mount Emei basalt is a mantle plume episodic eruption, providing new research directions and data for the evolution and eruption time limit of Mount Emei basalt mantle plume and its relationship with Permian biological extinction.
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A review of the role of phosphate in endogenetic carbonatite-hosted rare earth deposits
XU Danni, SONG Wenlei, YANG Jinkun, CHEN Qian, LIU Taotao, XU Yitong
Abstract:
The carbonatite-type rare earth (REE) deposits are the primary source of REE in the world. Phosphate is a common component in this mineralization system, but there is still a lack of systematic understanding of its role in the REE mineralization process of carbonatite. This article reviews the role of phosphate in the origin, evolution, and REE enrichment of the carbonatites and proposes current problems and research prospects. Phosphorus has a very high solubility in the carbonate melt. The presence of phosphorus is conducive to the preferential partitioning of REE into carbonate melt during the extremely low-degree mantle partial melting process and the carbonate-silicate liquid immiscibility process, therefore, forming a pre-enrichment of REE in the initial carbonatitic melt. During the evolution of carbonatite magma, REE will preferentially enter immiscible phosphate melts or phosphate minerals such as monazite and apatite. The behavior of these melts and minerals is likely to be a key factor controlling the behavior and mineralization potential of REE in the system. The REE-rich phosphate mineral formed during the magmatic stage can also be a source of REE mineralization in hydrothermal processes. Phosphate mineral is also an effective precipitator for REE in the hydrothermal process, which is conducive to mineralizing light and heavy REE in the late hydrothermal fluid stage. Future, more attention should be paid to the role of phosphate in the evolution of the carbonatitic magmatic stage and the enrichment mechanism of heavy REE in this system, and experimental petrology and melt inclusion studies should be carried out for specific mineralization processes.
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The First Discovery of Middle Jurassic Basalts in Northwest Hebei Province and Its Geological Significance
Abstract:
The author first discovered the basalt assemblage at the bottom of the Tiaojishan Formation in Xuanhua -Zhuolu, Zhangjiakou City.This paper takes the basalt at the bottom of the Tiaojishan Formation as the research object, and conducts petrology, geochemistry and chronology research.IThis article obtained a LA-ICP-MS zircon U-Pb age of 164.3 ± 2.6 Ma in basalt, dating from the Middle Jurassic, representing the lower limit age of the Tiaojishan Formation.The basalt contains 39.49%~49.74% SiO2, which belongs to the Alkali basalt series.
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Geochemical characteristics, zircon U-Pb ages and Hf isotopic compositons of Baitai granite in Jiulong area, western Sichuan, and their significance for rear metals mineralization
HU Junliang, TAN Hongqi, NI Zhiyao, ZHOU Jiayun, ZHU Zhimin, ZHOU Xiong, LUO Zhihong, YUE Xiangyuan, NIU Teng, XU Li, Huang Chixuan
Abstract:
To reveal the petrogenesis of Baitai granite in Jiulong area and its relationship with rare metal mineralization, petrographic, whole-rock geochemistry, LA-ICP-MS zircon U-Pb geochronology, zircon trace element geochemistry and Hf isotope geochemistry were studied in this paper. Samples from the Baitai biotite monzonitic granite are characterized by high SiO2 contents of 69.01%~70.55%, high K2O contents of 3.86~4.99%, high alkali contents (K2O+Na2O) of 7.41%~8.18%, low CaO contents of 1.49%~2.2%, low MgO contents of 0.44%~0.57%, with σ of 2.03 ~ 2.43, and A/CNK of 1.07~1.14. These granite samples could be ascribed to peraluminous-weak high-K calc-alkaline series, with the characterics of enriched in large ionic lithophile elements (K and Rb), and depleted high field strength elements (Nb, P and Hf). In chondrite normalized rare-earth element pattern, they show obvious right deviation type characterized by enrichment of light rare earth elements and depleted in heavy rare earth elements. The biotite monzonitic granite was formed at 213 ~ 212 Ma, and the zircon εHf(t) values ranges from -7.4 to -1.1, with the TDM2 age of 1.6 ~ 1.2 Ga. In conclusion, we propose that the Baitai I-type granite developed in a postcollisional extensional regime in the Late Triassic, and that it was related to an induced mantle upwelling after the delamination of thickened lithosphere following the final compression collision of the Songpan-Garze terrane. At the same time, the Baitai pegmatite-type beryllium deposits are closely related to the Baitai granite, which are derived from the residual crystallization products of the Baitai granite.
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A New Avian Footprint from the Lower Cretaceous of Zhucheng, Shandong Province
ZHANG Yanxia, SUN Yejun, CHEN Jun, CUI Weisheng, CHEN Shuqing, WANG Zengtao
Abstract:
Ignorannis mcconnelli from Dakota Group reported by Mehl in 1931 was the first widely accepted Mesozoic bird footprints. At present, Cretaceous avian footprints are reported in Asia, North America, Europe, Africa and South America, especially in East Asia. The Zhangzhuhewang dinosaur footprint site in Zhucheng, Shandong Province has preserved a complete avian footprint from the Early Cretaceous. This article provides a detailed description and comparison of this avian footprint, and believes that this avian footprint is different from the avian footprints previously discovered. Therefore, according to its morphology, a newavian track taxon, zhuchengornipes exquisitus is established. The footprints may have been created by shorebirds, and the footprints were formed in the coastal and shallow lake environment of arid climate.
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Sedimentary facies and environment evolution of the Upper Cretaceous zongzhuo formation in the Rongbu area, Southern Tibet, China
Abstract:
As an important component of Mesozoic marine sediments, the Zongzhuo Formation has recorded the Cretaceous paleoclimate and paleoclimate information in Southern Tibet. Based on the study of sandstone observation, provenance analysis and grain size analysis, this paper has a new understanding of sedimentary facies types and sedimentary environment evolution of zongzhuo formation in Rongbu area. The grain size analysis of sandstone samples of zongzhuo formation indicates that the water transport force is weak and turbidite deposits exist during the sedimentation period Microscopic observation, geochemistry analysis and zircon U-Pb age analysis of the three types of sandstones in the zongzhuo formation indicate that the provenance of the three types of sandstones is different. The zongzhuo formation has identified three types of sedimentary facies, namely shelf facies, continental slope facies and deep-sea basin facies. The Late Cretaceous new Tethys Ocean crust subducted northward, and the initial collision between the Indian and Asian continents occurred after the subduction. Based on the analysis of the tectonic setting of the study area, this is the reason that the sedimentary environment of the study area has changed from semi-deep sea environment to deep sea environment. Based on the analysis of the stratigraphic and sandstone sources of the zongzhuo formation in the study area, it is concluded that the zongzhuo formation was deposited at the passive continental margin during the oceanic subduction stage, and then at the initial collision stage of the india-asia continental collision, the passive Himalayan continental margin of the Tethys has ceased to exist and has completely transformed into a foreland basin.
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Phosphate enrichment and sedimentation in Lower Cambrian Maidiping Formation, Xiaogou, Sichuan
Wang Chang, Cheng Wenbin, Zhang Yu, Yang Yuchuan, Jin Canhai, Dong Shuyi, Zhang Jun, Zhao Wei, Li Chengze
Abstract:
In order to understand the accumulation and sedimentation mechanism of dissolved phosphate in seawater, the Xiaogou phosphate ore was studied by Raman and LA-ICP-MS. The results of laser Raman showed that phosphorus particles were composed of apatite, organic matter, silica and a small amount of pyrite, which verified the microscopic observation results and provided mineralogical basis for the determination of phosphate enrichment mechanism. Negative Ce anomalies were observed at all the test points by LA-ICP-MS analysis, indicating the conditions of Oxid-Suboxic bottom water and pore water in the sedimentation and mineralization process. The fossilized microorganisms found in the samples were reported, and it was speculated that they might be Eoentophysalis and Obruchevella. It is concluded that :(1) the Bio-organic deposition, plays an important role in the phosphorous formation process of Xiaogou phosphate deposit. (2) Extracellular polymeric substances（EPS） stick to cells and organic detritus in the process of mineralization, which leads to the aggregation and deposition of organic particles and provides material basis for the release of phosphate. In the later stage, EPS provides a large number of nucleation sites for phosphorus aggregation and promotes the rapid precipitation of phosphorus particles. This study focuses on the phosphate enrichment mechanism of Early cambrian Maidiping Formation in Xiaogou phosphate mine, which provides a basis for the genetic study of Early cambrian phosphate block.
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U-Pb dating of detrital zircons and geochemical characteristics of Inkisi Formation in the northeastern Angola area
lichunjia, zhanghongrui, luodike, jinlijie, gaojilei, wangzisheng, liangyunhan, jiapengfei, liuwei, zhangpan
Abstract:
Inkisi Formation is one of the earliest sedimentary strata in the southwest margin of Congo Basin. Its lithology is mainly a set of purplish red, reddish-brown fine-grained, fine-medium-grained arkose and gray-grained arkose. Detrital zircon dating and petrogeochemistry of Inkisi Formation are carried out to explore its depositional age, material source, sedimentary environment and tectonic setting, providing scientific basis for the study of the evolution of the Congo Basin. The results show that the 206Pb/238U age of detrital zircon is mainly concentrated in the three peak age ranges of 2350-1900Ma, 1150Ma-850Ma and 850Ma-500Ma. The peak age of the youngest zircon is 531±9Ma. The upper limit of depositional age of Inkisi Formation in this area is the Early Cambrian. The geochemical characteristics of the sandstone of Inkisi Formation show that the provenance has the characteristics of near-source transport of felsic provenance, and the water in the sedimentary period was an open freshwater environment of continental facies. Based on the age spectrum of detrital zircon, source identification of major trace elements and structure identification diagram, the results show that the West Congo tectonic zone is the main provenance zone, followed by the Lufilian tectonic zone and Angola shield. The tectonic environment of its provenance area is mainly active continental margin and passive continental margin tectonic environment background.
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Renjiatan-Qiaomaishan potassic intrusive rocks in the southern margin of North China : Petrogenesis and its implications for the late Paleoproterozoic breakup
LIYi, LI Zuochen, ZHAO Duangchang, ZHAO Pengbin, LV Junli, ZHANG Yafeng
Abstract:
In the southern margin of North China Craton, a series of alkaline rocks of 1.8 ~ 1.6 Ga were found in Luonan, Shaanxi Province, and the west area of Henan Province. The study of these alkaline rocks can facilitate the understanding of the Paleoproterozoic tectonic environment of the southern margin of the North China Craton. This paper systematically studied the potassic alkaline intrusive rocks in the Renjiatan-Qiaomaishan area in Luonan County, Shaanxi Province in terms of petrology, LA-ICP-MS zirconium U-Pb geochronology, Lu-Hf isotope analysis, and petrogeochemistry and discussed their genetic mechanism and tectonic setting. The results show that the main lithology of the rock mass in the Renjiatan-Qiaomaishan area is syenite porphyry, with a weighted average age of 1689 ± 20 Ma ( MSWD=0.12 ), which indicates that the emplacement of the rock mass happened in the Paleoproterozoic area. The rock mass is rich in alkali ( Na2O+K2O=7.95% ~ 9.5% ) and high in potassium ( K2O=4.67% ~ 8.51% ). The total amount of rare earth elements is high ( 496.15×10-6 ~ 650.16×10-6，average 543.06×10-6 ) , and the fractionation of light ( LREE=454×10-6 ~ 605×10-6 ) and heavy rare earth elements is obvious ( HREE=39.3×10-6 ~ 45.6×10-6 ). The light rare earth elements are relatively rich, while the heavy rare earth elements are deficient, and there is a weak negative europium anomaly. In addition, K , Rb , Ba , Th is rich, while Nb , Ta , P , Ti is deficient, and there is an obvious negative Sr anomaly. The value of εHf ( t ) is less than 0, the value of TDM1 is 2038 ~ 2218 Ma and TDM2 is 2250 ~ 2516 Ma , indicating that the materials in the magmatic source area are related to the enriched mantle or contaminated by the crustal materials. Therefore, the rock mass in the Renjiatan-Qiaomaishan area is a melt formed by mixing the basaltic magma of the mantle with the medium-acid granitic magma formed by the Taihua complex TTG crust. It was formed in the tectonic environment of an intracontinental rift through strong crystallization differentiation, reflecting a response of the southern margin of the North China Craton to the cracking event of the Columbia supercontinent.
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Petrogenesis of Fuling A- type granite in the southern Anhui Province：Constraints from petrogeochemistry , Zircon U-Pb age and Lu-Hf isotope characters
zhengwei, chentianhu, dujianguo, chenfang, dingning, zhangshu
Abstract:
Objectives: The Fuling pluton is a granitic body located in the adjacent area of Anhui and Zhejiang provinces in the eastern section of the Jiangnan orogenic belt. The magmatic rocks are distributed along the Ningguo-Jixi deep fault extending near the NE direction. The research work on the Yulongchuan (γ53 (2) )unit granite in Fuling Pluton has been carried out in this paper. Methods: Based on the field work, we finished microscope observation, whole-rock geochemical analysis, LA-ICP-MS zircon U-Pb dating and in situ Lu-Hf isotope geochemistryfor the Yulongchuan (γ53 (2) ) unit granite. Results: The LA-ICP-MS zircon U-Pb dating shows that the emplaced age of the granite is 131.75±0.91Ma, which is the product of magmatic activity in the late stage of the Jiangnan orogenic belt. The pluton is rich in silica and alkali, and poor in calcium and iron. The characteristics of trace elements show that there are higher Rb, Th, U, Ga, Zr and Y contents, and there are lower Sr , Ba and Nb. The rare earth partition curve presents a typical "seagull" distribution, showing strong negative Eu anomalies. Negative anomalies of Ba, Sr and Nb are found in the primitive normalized mantle spider map of trace elements. The zircon εHf (t) of Fuling granite varies from -7.0 to -4.6, and the two-stage model age (TDM2) ranges from 1478 to 1630Ma. The Th/U values, Th/Nb values and Th/La values are all higher than the average continental crust value, and the La/Nb values is slightly lower than the average continental crust value. Conclusions: The high SiO2 content, Rb/Sr value and low Ba and Sr content show that the Fuling granite has the typical characteristics of the A-type granite in the eastern part of Jiangnan orogenic belt, southern Anhui Province. The Fuling pluton has the characteristics of homologous magmatic evolution, and the separation and crystallization of apatite and ilmenite minerals may exist in the source area, while the separation of pyroxene minerals is less. The source rocks of Fuling pluton are mainly derived from partial melting of mafic rocks in the crust, and their geochemical characteristics are inherited from the source rocks. The Fuling granite may have been formed by partial melting of the ancient lower crust in Mesoproterozoic, and its source material is mainly the ancient lower crust. The positive δEu anomaly of Fuling pluton and the high Sr content of some samples indicate that the magma source is deep. These geochemical characteristics all indicate that the formation of Fuling granite may have been mixed with mantle materials.The formation of Fuling pluton may be influenced by collision. The rock mass was formed in post-collision. Asthenosphere upwelling led to the melting of the subcontinental lithosphere mantle, which produced a large number of new basaltic magma. Thus, Fuling A-type granite is produced.
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Formation age, geochemical characteristics and tectonic significance of Biqigenao pluton
ZHANG Jianchao, ZHU Kongyang, YANG Bo, SU Meixia, XU Liquan, ZHOU Fei, DONG Chuanwan, SHEN Zhongyue, WU Yanjun, MENG Xiaoling, She Linlin
Abstract:
The Biqigenao pluton is composed of two phases of intrusions, the lithology of which is granodiorite and monzogranite, the former being the main lithology of the pluton. Granodiorite is mainly composed of plagioclase (An = 15 – 30), quartz, alkali feldspar and amphibole, with mafic microgranular enclave inside; The monzogranite is mainly composed of quartz, alkali feldspar and plagioclase (An = 10 – 20). Zircon U-Pb dating shows that the pluton was formed in the Late Permian, and its formation age is 259 Ma. The main granodiorite with SiO2 = 66.37% – 68.70% is aluminous-weakly peraluminous (A / CNK = 0.99 – 1.01), which is characterized by enrichment of light rare earth and large ion lithophile elements, depletion of heavy rare earth and high field strength elements, belongs to I-type granite; mafic microgranular enclave is rounded or elongated flat lenticular, and the age is consistent with the granodiorite, which is the product of magma mixing; Monzogranite is high silica granite (SiO2 = 71.51% – 73.09%), alkali-rich (Na2O + K2O = 7.91% – 8.61%) and weakly peraluminous to strongly peraluminous (A / CNK=1.07 – 1.11), is a differentiated I-type granite. The εHf (t) of Ziron distribution range is ? 3.0 – 3.4, and the corresponding Hf isotope two-stage model age is 1473 – 1057Ma. It has relatively low (87Sr/86Sr) i value (0.704829 – 0.705327), ε Nd (t) value is ? 5.85 – ? 8.86, and the corresponding Nd two-stage model age is 1.69 – 1.45 Ga. Based on the regional research data, it is considered that the Biqigenao pluton is formed by mixing the depleted mantle component with the partially melted ancient crustal material induced by it, and belongs to the post-collisional granite.
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Deposition time and tectonic background of Baoshuping Formation，Erlangping Group in North Qinling
zhaiwenjian, zhangyong, tangguosheng, zhaohuan, zhaiwenfang
Abstract:
The Baoshuping Formation of the Erlangping Group is an important Early Paleozoic sedimentary record in the North Qinling, but it has been relatively under-studied. This study aims to further determine its depositional age and tectonic environment through petrological, geochemical, and zircon U-Pb dating investigations of volcanic interbeds and granite veins within the Baoshuping Formation. The research results indicate that the lithology of the volcanic interbeds of the Baoshuping Formation in the Xiaguan area of western Henan Province is biotite actinolite sodium schists, often interbedded with biotite quartz schists. The protolith of the rocks is andesitic tuff, characterized by relatively low SiO2 (52.56%–62.04%), relatively high Al2O3 (10.70%–18.55%), low MgO (4.06%–6.21%) and FeOT/MgO (1.23–1.81). It is enriched in light rare earth elements (LREEs)and large ion lithophile elements (LILEs, Rb, Th, U, K), and relatively depleted in high field strength elements(HFSEs, Nb, Ta, P, Ti), exhibiting characteristics of magnesian andesite rocks. Based on geochemical characteristics and previous studies, it is inferred that the Baoshuping Formation may have formed in an active continental margin back-arc basin. The crystallization age of the protolith of biotite actinolite sodium schists obtained by U-Pb dating of zircon is 446.0±1.7 Ma, and the crystallization age of the intrusive granite porphyry is 430.0±3.0 Ma, accurately dating the formation age of the Baoshuping Formation as Late Ordovician to Early Silurian for the first time. Integrated regional research results suggest that the Xiaozhai Formation and Baoshuping Formation conform to the division scheme of the generalized Erlangping Group in terms of stratigraphic sequence and stratigraphic age. However, the Damiao Formation, Huoshenmiao Formation, and the composite of the Xiaozhai Formation and Baoshuping Formation exhibit near-simultaneity in formation age and a nearly parallel spatial relationship, indicating that they are likely products of different depositional environments with roughly equivalent ages. In terms of tectonic attributes, it is believed that Erlangping Group formed as a volcanic island arc due to the northward subduction of the Shangdan Ocean before approximately 470 Ma, transformed into a back-arc basin between 470 and 436 Ma, and completed the subduction closure process before approximately 430 Ma.
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New ammonites in the Wayao member of the Falang Formation in Guanling area, Guizhou Province
Ma Zhiheng, Li shixin, Chen Jingwen, He Ben, Zhang Tingshan
Abstract:
This paper describes two ammonoid Arctosirenites mingqingensis sp. nov. and Klipsteinia cf. radiata from the Wayao Member of Falang Formation, Guanling county of Guizhou province. The Arctosirenites mingqingensis sp. nov is characterized by fine transverse ribs and umbilical knobs. Based on the combination of Klipsteinia and Arctosirenites, the age of upper part of the Wayao Member of Falang Formation in Guanling county of Guizhou Province is attributed to Tuvalian 1. It is also considered that the lithological changes at the bottom of the Wayao member of the Falang Formation are caused by tectonic factors rather than the influence of the Carnian Pluvial Episode.
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Evolution law of river network patterns in distributive fluvial systems: A case study of Golmud Fluvial Fan
WANG Haonan, ZHANG Changmin, SUN Jiahui, ZHANG Xianghui, XU Qinghai, LIU Hongping, Adrian J. Hartley
Abstract:
To explore the river network distribution of distributive fluvial systems, and to provide knowledge base information for creating reservoir modeling training images. Using modern geographic information software tools such as Google Earth, Global Mapper, and 91 Satellite Map Assistant, the surface river channel bifurcation characteristics of the modern Golmud Fluvial Fan were systematically measured. The river network pattern model of the fluvial fan was established using Horton's law and fractal methods. The results show that: 1) The Golmud River Fan has identified 26 river channels from the apex to the lake inlet section, 882 nodes and 2162 river sections. The river channels along the spring line and below show different river network patterns; 2) There are a total of 64 nodes developed in the upper part of the spring line, with an increase of RB=1.8900 times the number of rivers in each level compared to the previous level, and an average length of RL=1.0095 times that of the next level, indicating that the characteristic parameters of river network morphology are RB=1.8900 and RL=1.0095; There are a total of 818 nodes developed in the lower part of the spring line, with an increase of RB=1.0279 times the number of rivers in each level compared to the previous level. The average length of each level of river is RL=0.9899 times that of the next level of river, which means that the characteristic parameters of river network morphology are RB=1.0279 and RL=0.9899; 3) The characteristic parameters of river network morphology vary greatly due to the influence of slope. If the slope is larger, the characteristic parameters of river network morphology are larger, and if the slope is smaller, the characteristic parameters of river network morphology are smaller. The quantitative characterization of river network pattern characteristic parameters has promoted the development of sedimentology in distributive fluvial systems, providing new knowledge base information for conducting reservoir modeling and sand body prediction in continental basins.
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Characteristics of strike-slip transfer zone and its control on large-scale reservoir of buried hill in Liaobei area, Bohai sea
Hui Guanzhou, NIU Chegnmin, YANG Chuanchao, ZHANG Jiangtao, GUAN Chao, WANG Mingchun, ZHAO Jing
Abstract:
The buried hill strike-slip transfer zone is widely developed in the Bohai Sea area, but its development characteristics and reservoir control are weak. Based on drilling, logging, 3D seismic and other data, the development characteristics, genetic mechanism of structural transfer zone and their control effect on buried hill scale reservoirs in northern Liaodong Bay are analyzed. Study shows that under the background of sinistral strike-slip at the late Yanshan, many types of transfer zones are developed in buried hills in northern Liaodong Bay; According to the interaction of strike-slip faults and the shape of the tranfser zone, the buried hill transfer zone in northern Liaodong Bay can be divided into two types: single-branch bending type and double-branch overlapping type; According to the local stress state, it can be further subdivided into four subclasses: singl-branch anti "s" type, single-branch "s" type, double-branch left-handed right-order and double-branch left-handed left-order transfer zones. Among them, single branch anti "s" type and double branch left-handed right-order transfer zones belong to pressurized transfer zones, and single branch "s" type and double branch left-handed left-order transfer zones belong to pressure relief transfer zones; The compressive torsional dynamic crushing provided by the pressurized transfer zone makes the buried hill develop large-scale fractured reservoir, which is the key to the development of large-scale buried hill reservoir.
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A review of the application of deformation measurement methods in geomechanical model experiments
SU Zhandong, WANG Zhiwen, SUN Jinzhong, ZHANG Jianyong, LIANG Jinping, NIU Yao, ZHANG Zhitai, ZENG Yangnong, LI Mengyuan
Abstract:
As a convenient, efficient and low-cost research method, geomechanical model experiment can not only present the failure process of engineering intuitively, but also serve as an important research means to understand the overall mechanical characteristics, failure mode and stability of engineering. Therefore, geomechanical model experiments are widely used in the study of various geotechnical engineering problems. Due to the low deformation modulus of geomechanical model materials and their extremely sensitive strain under the same stress conditions, deformation measurement is crucial in model experiments. In order to improve the convenience and accuracy of deformation measurement in geomechanical model experiments, the main methods of deformation measurement in the current geomechanical model are summarized and analyzed. The results indicate that currently, the methods for measuring model deformation mainly include electrical measurement method, optical measurement method, and mechanical measurement method. Among them, electrical measurement method mainly includes resistance strain gauge method and displacement meter method, optical measurement method mainly includes fiber optic sensor method, digital image correlation method, photoelastic patch method, and moire interferometry method, and mechanical measurement method mainly includes percentage meter measurement method and theodolite observation method, through the explanation and comparison of the working principle, main application cases and advantages and disadvantages of various methods. The main difference between the different methods is the difference in the measurement range and the scope of application, among which the percentile meter method is suitable for measuring the deformation of a small area; To measure the internal deformation, the resistive strain gauge method and optical fiber sensor method can be selected; For deformation in larger areas, the displacement meter method and the optical fiber sensor method can be selected; The theodolite observation method can be selected for the specified point displacement; For full-field observation, digital image correlation method, cloud interferometry and photoelastic patch method can be selected. This achievement can provide an experimental reference for the experimental deformation measurement of related geomechanical models.
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Evaluation method and application of crude oil cracking gas resources — taking the Sinian-Cambrian of Sichuan basin as an example
GUO Zeqing, ZHAO Wenzhi, XIE Zengye, WANG Zhihong, Jiang Hua, LI Jian, ZHU Guangyou
Abstract:
The Sinian-Cambrian natural gas resources are abundant in Sichuan basin. In recent years, two giantSgas-accumulatingSareas with trillion cubic meters reserves have been discovered in the central Sichuan palaeo-uplift and northern slope areas of the Sichuan Basin. However, the specific scale of resources and the future exploration direction in this field are still unclear. In this study, based on the basic understanding that the natural gas in this area came from the cracking of crude oil in ancient oil reservoirs, the resource amount of crude oil cracking gas was calculated according to the technical route of kerogen generating oil and then cracking gas from ancient oil reservoirs. The formation thickness maps, lithofacies palaeogeography maps, comprehensive evaluation maps of hydrocarbon source rock, erosion thickness maps and oil generation dynamics parameter plates were inputted to PetroMod 3D basin simulation software, and the 3D geological model was established to calculate oil generation in five primary tectonic units and restore the oil generation history, and the critical moment of ancient oil reservoir formation was clarified. Then, the oil migration and accumulation coefficient, oil cracking rate, gas loss rate and the partition coefficient of Cambrian oil migration were discussed, and the calculation formula of natural gas loss coefficient was established. Finally, the conventional natural gas resources of the Sinian and Cambrian in the whole basin are 13.43 trillion cubic meters, including 5.43 trillion cubic meters in Cambrian and 8.0 trillion cubic meters in Sinian. It is also pointed out that apart from central Sichuan, southern and eastern Sichuan have great exploration potential, especially the platform margin zone and intra-platform granular beach located on both sides of Deyang-Anyue rift in southern Sichuan are the practical areas for further exploration. On the one hand, this study provides a set of practical and feasible evaluation methods for the crude oil cracking gas resources; On the other hand, it has implemented the resource potential of the natural gas of the Sinian - Cambrian system in Sichuan Basin and strengthened the exploration confidence. This study is of great significance in theoretical innovation and exploration practice.
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Statistics and analysis of basalt fiber raw material characteristics
LiZhen, XU Guanli, LIU Rong, SHI Kaiwen
Abstract:
Basalt fiber is a kind of high-performance fiber manufactured by melting and drawing from basalt or rocks of similar composition. Fluctuation in the composition of natural rocks can cause difficulties in drawing and instability of fiber properties. This paper collected data on the chemical composition of 54 groups of raw rock and 114 groups of basalt fiber samples. The petrological, parameter index and other characteristics of the raw material needed for basalt fiber were summarized, and the optimal range of related parameter indexes of raw materials were proposed. The characteristics of raw rock which is suitable for the production of basalt fiber can be summarized as follows: from the perspective of petrology, basic rocks or intermediate rock with a SiO2 content of 53% to 57% are the optimal; the most suitable rock type is basalt or andesite; the most appropriate rock texture is intersertal texture, vitrophyric texture or hyaline texture. The influence of structure is indirect, mainly due to some adverse minerals which may be contained in fumarolic structure or amygdaloidal structure. From the perspective of mineral composition, hydrous minerals such as serpentine and zeolite will cause bubbles in the melt, which will affect the continuity of fiber preparation but will be conducive to the full melting of raw materials. High melting point minerals such as forsterite and magnetite will make it difficult for raw materials to melt completely, resulting in uneven melt and easy crystallization. From the perspective of parameter index, the optimal range of acidity coefficient (Mk) is 4.0 to 5.5. The viscosity coefficient (Mv) is 2.0 to 3.0. The ratio of silicon aluminum oxides to other oxides is 1.5~3.0. The molar fractions of oxides are n(RO) = 20% to 30%, n(RO2) = 57% to 70%, and n(R2O3) = 10% to 16% (R stands for cations).
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Geochronology, geochemistry and geological implications of the Early Paleozoic intermediate-basic complex in the upper reaches of Pangu river of the northern Great Xing’an Range
LI QIANG, CHENG Xueqin, WANG Yankai, LI Zhimin, LIU Hongzhang, YANG Ning, SHEN Jinqing, LUO Shanxia
Abstract:
The origin, source characteristics and dynamic background of the Early Paleozoic magmatic rocks in the Erguna massif are of great significance for revealing the tectonic evolution history of the restoration area. In this paper, the Early Paleozoic intermediate-basic complex in the upper reaches of Pangu River in the Northern of Great Xing’an Range was selected for petrology and zircon U-Pb chronology and petrogeochemical analysis. Field investigation and laboratory study show that the rock types of the complex are mainly hornblende gabbro and gabbro, rare quartz diorite, diorite, pyroxenite, olivine gabbro and other intermediate rocks or ultrabasic rocks. The dating results show that the formation age of the hornblende gabbro is 479.2±2.1Ma, indicating that the complex was formed in the Early Ordovician. In terms of geochemical composition, the Early Paleozoic intermediate-basic complex rocks in the upper reaches of the Pangoo River have SiO2 contents ranging from 40.74% to 54.95%, Fe2O3T contents ranging from 3.99% to 14.66%, MgO contents ranging from 3.36% to 17.78%, Mg# values ranging from 47 to 79, which are (high potassium) calc-alkaline series rocks, relatively enriched in light rare earth elements and depleted in heavy rare earth elements with δEu from 0.77 to 2.06. Furthermore, they are relatively enriched in large ion lithophile and radioactive elements such as Rb, Ba, U, K, Pb and Sr, and depleted in high field strength elements such as Nb, Ta and Ti, which is similar to the geochemical characteristics of arcmagmatic rocks in subduction zone. The magma was originated from partial melting of mantle dominated by subduction fluid metasomatism supplemented by sediment melt metasomatism. The source area is dominated by spinel bearing garnet lherzolite, and a small amount of spinel lherzolite, which experienced different degrees of crystallization differentiation in the rising process. Combined with the regional lithostratigraphic data, comprehensive analysis shows that the Early Paleozoic intermediate-basic complex in the upper reaches of Pangu River was formed in the tectonic environment of continental extensional zone (or initial rift), which is probably related to the lithosphere extension background after the collision between the Siberian plate and the Erguna massif.
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The volcanic rock characteristics and magmatic evolution of the Xingshan volcanic group in the Jingpohu area
Guo Kexin, Liu Yongshun, Nie Baofeng, Guo Lei, Zhang hui, Huang Zhicong, Hou Peng, Li Yao
Abstract:
Jingpohu volcanic field is an important window for the study of intra-continental Cenozoic basalts. Previous studies on Xingshan volcanic group located in the southeast of this area have rarely been conducted and the possibility of magma assimilation and mixing in this area has been denied. The basalts of Xingshan volcanic group have been systematically studied in terms of petrology, petrochemistry and Sr-Nd-Pb isotopes. It is believed that the basalts of Xingshan volcanic group are mainl alkali basalts and trachytic basalts. The fractionation of olivine and clinopyroxene occurred during the ascent of the primary magma, and the assimilation and mixing occurred in the upper crust, with weak AFC effect. The comparison between the basalts of Xingshan volcanic group and the Jingbohu basalts shows that the alkalic basalts in both areas are derived from the partial melting of garnet peridotite, and the partial melting degree of Xingshan volcanic group is slightly lower than that of Jingbohu basalts. In terms of magmatic source region, the Xingshan volcanic group is the mixed source of PREMA and BSE end-member, while the Jingbohu basalts are the mixed source of EMII and BSE end-member at the same period. The heterogeneity of magmatic source region and the difference of magmatic evolution are the main factors causing the difference.
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Geochemistry, Ziron U-Pb dating, and Hf isotopics characteristics of ore-forming granite porphyry in Tieshanlong W ore field, southern Jiangxi Province
LI Wei, TANG Juxing, GUO Na, LIAN Dunmei, 江西省地质局第七地质大队
Abstract:
Tieshanlong W ore field is located in the eastern section of Nanling W-Sn-polymetallic metallogenic belt, which have produced more than 100000 tons of wolframite around the Tieshanlong granitic complex. There have three kinds of granites: the early coarse-grained porphyritic biotite granite, the complement fine grained muscovite granite and latest granite porphyry veins, showing common geochemical characteristics of peraluminous, high-K and calc-alkali category, integrated with enrichments of SiO2, Al2O3, K2O, W, Sn, Cu, Mo, depletions of Ba、Sr、Ti、P、REE and Eu negative anomaly. Their rare earth distribution curve shows a typical “seagull” distribution with M-type tetrad effect. LA-ICP-MS zircon U-Pb dating of granite porphyry yields emplacement age of 146.7±0.5 Ma (MSDW=0.5), with 176Lu/177Hf and fLu/Hf rations of 0.000 973～0.001 989 and ﹣0.97～﹣0.94, respectively. The εHf(t) values range from ﹣17.9 to﹣10.3, and TDM2 are 1.86 Ga to 2.33 Ga, indicating primary reworking of the Paleoproterozoic crustal material. The comprehensive analysis shows that Tieshanlong ore field have three stages magmatic activities of 160～154 Ma, 154～151 Ma and 148～145 Ma, and the W-Sn mineralization is mainly occurred in the second stage. Granite porphyry is rich in Cu, Mo, W, which is closely related to the Cu-W mineralization, and show a great prospecting potential in the deep part of Tongling deposit.
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Emblem: Cultural Expression of Geological Societies
Zhang Jingfei, Wen Heng, Tatiana Fecklovia, Zhang Jiuchen
Abstract:
The emblem is a professional, historical, and academic logo. As an information carrier, it expresses academic groups' academic purpose and mission with simple, vivid and easily recognizable images. At the same time, it shows academic groups' scientific and cultural connotations, such as their work objectives and academic spirit. Taking the emblem of the Geological Society of China as an analysis case, this paper discusses the role of the emblem in the scientific and cultural construction of the Society by comparing it with the cultural aims and connotations of several representative geological societies in the East and the West.
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Deformation events and the attributes of ore-controlling structures in the Yanlinsi gold field and its adjacent areas in eastern Hunan
Bai Daoyuan, Wei Fanghui, Li Bin, Zeng Guangqian, Sun Ji, Zhou Chao
Abstract:
The Yanlinsi gold field is located in the south of the northeastern Hunan gold mining area, where a large number of small and medium-sized gold deposits are developed. Predecessors have not explored and analyzed the kinematic characteristics, formation ages and mechanisms of various types of deformations including ore-controlling structures in the area, affecting a comprehensive understanding of the formation and preservation laws of ore deposits. In view of this, based on the regional structural characteristics and detailed analysis of a large number of surface outcrop structures, the authors determined the deformation sequences and their ages of the Yanlinsi gold field and its adjacent areas, and then combined with deposit geology and isotope dating, discussed the mineralization ages and attributes of ore-controlling structures. The main achievements are as follows: (1) The study area has experienced 9 tectonic events from early to late such as regional NW compression in the middle Neoproterozoic, NW compression in the early Silurian, active emplacement and compression of granite bodies in the late Silurian, NW compression in the late Middle Triassic, NNW to SN compression in the Late Triassic, NWW to EW compression in the late Middle Jurassic, NW-SE extension in the Cretaceous, NE to NNE compression in the middle-late Paleogene and NW compression during the late Paleogene to early Neogene, resulted in different trends and scales of structures such as folds, thrust faults, bedding shear zones, normal faults, dextral and sinistral strike-slip faults and shear fractures, faulted basins, cleavages and kinks, as well as late deflections of some structural trends. (2) There were two stages of gold mineralization in the area during the late Silurian and late Triassic, both of which are related to contemporaneous granitic magmatic activity. (3) The main ore-bearing structures in the Yanlinsi gold field include three types: pre Mesozoic bedding brittle-ductile shear zones and interlayer faults, NW- to NWW-trending dextral strike-slip faults and shear fractures formed during Middle to Late Triassic, and internal and external contact zones of granite branches. The ore-passing structures of the late Silurian gold deposits were pre NE-trending deep thrust faults, while those of the late Triassic gold deposits were NE-trending thrust faults in the late Middle Triassic, NEE- and EW-trending thrust faults in the early Late Triassic. For the two stages of gold deposits, different types of faults formed during each deformation events after mineralization may become ore-breaking structures.
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Detrital Zircon U-Pb Geochronology and Hf Isotopic Characteristics of Middle Jurassic Sandstone in the Santanghu Basin of East Junggar and their Significance to Uranium Mineralization
LIU Min), ZHOU Yu), SU Fei), YUAN Yanwei), ZHU Yongsheng), XING Jianlei)
Abstract:
Objectives：This paper provided petrography, LA-ICP-MS zircon U-Pb age, and zircon Hf isotopes of the middle Jurassic sandstone in Hanshuiquan area of Santanghu basin, analyses the source of clastic materials and its indication for sandstone-type uranium mineralization. Methods：Based on the field work, through the microscopic observation, the LA-ICP-MS zircon U-Pb isotopic chronology, and the LA-ICP-MS zircon Lu-Hf isotopes of malmstone. Result：The detrital zircon ages of the sandstone in Xishanyao Formation are distributed in the Late Paleozoic, and the peak ages of the two samples are 328Ma and 340Ma. The detrital zircon εHf(t) ranges from+8.9to+14.7, and the two-stage model age ranges from 690 to 415 Ma. Clastic zircon ages of sandstone in Toutunhe Formation can be divided into three sections: 238~163Ma, 505~259Ma and 1950~744Ma. Clastic zircon εHf(t) is -6.5~+12.1, and the two-stage model age is between 1709~575Ma. Conclusion：The Xishanyao Formation has a single source of material, mainly from the western Karamaili Maiqinwula and Yemaquan regions; The source of the Toutunhe Formation is relatively complex, and in addition to the detrital material from the Karamaili region, it also receives supply from other regions. The sudden change in age characteristics of detrital zircons between the two represents a severe tectonic deformation event in the Middle Jurassic of the East Junggar region. The source characteristics indicate that the uranium content in the Middle Jurassic strata in the Hanshuiquan area is relatively limited, and uranium source is an important factor limiting the mineralization of sandstone type uranium deposits in the area.
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Ore - bearing rock series of Liangshan Formation bauxite in Kaili - Huangping area, southeast Guizhou
Liu Ping, Han Zhonghua, Nie Kun
Abstract:
[ ] The Dazhuyuan Formation ( C2d ) in northern Guizhou-southern Chongqing and the Liangshan Formation ( P2 l) in Kaili-Huangping area of southeastern Guizhou are both ore-bearing rock series of bauxite, both of which produce abundant spore pollen. According to the identification of pollen experts and other geological characteristics, the sedimentary age of Dazhuyuan Formation is Late Carboniferous Xiaoyao period, namely Kasimovian-Gescher period. The sedimentary age of Liangshan formation is the early Luodian period of Middle Permian, namely the early Empty Valley period. "China Mineral Geology . Guizhou Volume . Bauxite " ( 2019 ) Chapter 6 " Kaili-type Bauxite ", in the absence of geological evidence, the original Middle Permian Liangshan Formation in the Kaili-Huangping area was dismembered into two parts : the upper part of the original Liangshan Formation, carbonaceous shale, coal seams, quartz sandstone, etc. are still called the Middle Permian Liangshan Formation ( P2l ) " ; the bauxite, bauxite rock in the middle section of the original Liangshan Formation and the iron clay rock and siderite layer in the lower section were changed to the Lower Permian " Dazhuyuan Formation ( P1d ) ", and its sedimentary age was determined as " Early Permian Sakmar-Adingsk period, equivalent to the late purple period-Longlin period in China ". In this way, it will cause confusion to the stratigraphic units of the Middle Permian Liangshan Formation in Guizhou Province, which has been used for many years and has a clear definition, layered and sublayer support, which deserves serious attention.
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Sedimentary and Sequence Stratigraphic Characteristics of Kepingtag Formation in Tarim Basin——Taking Aqia Section in Keping Area as an example
Wang Zhenghe, Zhang Ronghu, Yue Yong, Yu Chaofeng, Yang Zhao, Zhi Fengqin
Abstract:
The third-order sequence division of the Silurian Kepingtage Formation in the Tarim Basin were different based on different research locations or areas, which restricted the understanding of the regional tectonic-sedimentary evolution and the direction of oil and gas exploration of this strata. Therefore, combined with outcrops, published wells and seismic, existing research results, a detailed analysis of the sedimentary and sequence characteristics of the outcrop of the Kepingtage Formation in the Aqia area, Keping, shows that:(1)The Kepingtage Formation in Aqa area, on the western edge of Awati sag, is mainly a delta sedimentary system controlled by mixed hydrodynamics dominated. From bottom to top, the lower member is a sedimentary cycle from fining-up to coarsing-up, and the middle and upper members form a coarse-up sedimentary cycle as a whole. (2) The unconformity surfaces at the top, bottom and inside of the Kepingtage Formation can divide it into two third-order sequences. The lower member of which constitutes SQ1,with LST, TST and HST. The middle and upper members constitute SQ2, with only TST and HST.(3) The boundary between the middle and lower members of the Kepingtage Formation may correspond to the unconformity formed by the sea level decline during the glacial period in the Late Ordovician Hernantian. (4) As the hydrodynamic conditions of different system tracts are different, the LST is dominated by river effect, while the wave and tide effect is greater than the river effect in HST. (5) TST in SQ2 is a regional high-quality cap rock, which can form a good cap-reservoir combination with HST in SQ1. Therefore, HST of SQ1 on the western edge of Awati sag can be the primary exploration target in this strata.
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Growth mechanism of Neoproterozoic Ganjingzi Formation stromatolites in southern Liaoning: Comparison with modern stromatolites
YUAN Dingcheng, ZHANG Yongli, LAI Guanming, GONG Enpu, WANG Junjie, LI Depeng
Abstract:
Objectives：The Ganjingzi Formation stromatolites in southern Liaoning Province are an ideal object for studying the construction of early Neoproterozoic microbial carbonate, which is of great significance for restoring paleoenvironment and paleoecology. Methods：Based on field investigation, the position of the outlying stromatolites in the Ganjingzi Formation, the macroscopic morphological characteristics of stromatolites, and the morphological changes of stromatolite columns and lamellar structures are identified and recorded. Through the observation of the laminae, the different growth stages of the laminae are distinguished, and the influence of the environment on the bifurcation and morphology of the stromatolite columns are analyzed. The stromatolites building process and characteristics of Neoproterozoic the Ganjingzi Formation stromatolites are reconstructed by comparing them with modern stromatolites. After comprehensive discussion, the growth mechanism of the Ganjingzi Formation stromatolites is summarized. Results：According to different lithology, the Ganjingzi Formation is divided into three sections from bottom to top in the Yuanjiagou area, southern Liaoning Province. Stromatolites appear at the bottom of the lower member and the top of the upper member of the Ganjingzi Formation. The stromatolites at the bottom produce stromatolite mound or the large-scale stromatolite biostrome at the top. The stromatolites colonize the hard substrate and grow perpendicular to the substrate at the beginning stage. Under the influence of hydrodynamic conditions and photosynthesis, stromatolites gradually grow vertically upward. The stromatolites in the stromatolite mound present a pattern combination of corrugate-columnar-cumulus, and the stromatolites in the stromatolite biostrome present a pattern combination of corrugate-columnar-long columnar, both of which reflect the changing trend of stromatolite morphology with increasing water depth. A comprehensive comparison of modern stromatolites shows that the microstructure of the Ganjingzi Formation stromatolites is similar to that of modern stromatolites, and growth and branch have certain comparability. Conclusions：The stromatolite laminae of the Ganjingzi Formation show different sequences of formation of light laminae and dark laminae. The morphological characteristics of stromatolites show that the growth and branched of stromatolites are affected by the environment to some extent. The formation of stromatolites is subject to environmental changes. The extensive growth of stromatolites requires ample space and a suitable environment. The presence of hard substrates creates favorable conditions for the growth of stromatolites. From micro to macro, the influence of biological factors on the growth and building characteristics of microbial mats gradually increased, while the influence of environmental factors gradually decreased.
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Principle and utilization of calcite twins geothermometer case study of Wufeng-Longmaxi Formation in southern Sichuan
yangyuran, liujia, liuzijun, hezeliang, yinyingzi, wangheng, wujuan, wuwei, linjiashan, dengbin
Abstract:
Due to the lack of traditional paleothermal indicators/geothermometer, the evolution of basin thermal history and paleothermal field characteristics of the deep and ultra-deep carbonate formation formation in the western basin of China are controversial. Taking calcite in the Wufeng-Longmaxi Formation in southern Sichuan as an example, combined with fluid geochemistry and thermal evolution history, calcite mechanical twins can effectively reveal the thermal history characteristics of Wufeng-Longmaxi Formation. Calcite mechanical twins have three evolution processes: twins dislocation formation, twins thickening and merging of thickened lamellage , resulting in different twins structures (thin, tabular thick, curved and tapered etc.) formed in environments below 170°C, 170-200°C and greater than 200°C, respectively, and with the increase of temperature, there are trend characteristics of decreasing twin density and increasing width. The Wufeng-Longmaxi Formation in Weiyuan area of southern Sichuan developed typical tabular thick calcite twins, with a width of 1-4 um and a density of 30-50 pieces/mm. The calcite twins of Changning Wufeng-Longmaxi Formation has a large width (about 3 um) and a low density (15-20 pieces/mm). The inclusion homogenization temperature and thermal evolution history showed that the peak of homogenization temperature in Changning was 120-140°C, 160-180°C and 200-220°C, and their buried heat history was significantly greater than that in Weiyuan area, which together revealed that the Wufeng-Longmaxi Formation in Changning area had a higher temperature for mechanical twins formation compared with Weiyuan area. Therefore, calcite mechanical twins morphological geometry can be applied as a typical geothermometer to the study of the thermal history of deep carbonate formation in western China.
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Discovery of a New Dinosaur Cemetery in Early Jurassic Strata in Xiangyun area of western Yunnan
HU Shaobin, liujunping, ZENG Wentao
Abstract:
Objectives: In 1938, the discovery of the first dinosaur fossil (Lufenglong) in Yunnan marked the beginning of the Jurassic dinosaur explosion in Yunnan. After generations of geologists' continuous research and excavation, the discovery of dinosaur fossils extended from the Lufeng area of Yunnan to the outside, followed by discoveries in Yimen Sunset, Jinning, Jiangyi, Wuding Wande, and Shuangbai Anlongbao in Yunnan, However, the discovery of these dinosaur fossils is concentrated in the central and eastern parts of the Chuxiong Basin, and there have been no reports on the western region of the Chuxiong Basin. Results:Through a comprehensive and systematic investigation of paleontological fossils, the author discovered for the first time the origin of dinosaur bone fossils in the Fengjiahe Formation of the Lower Jurassic in the Xiangyun area of western Yunnan. A preliminary fossil profile investigation and repair were conducted on the new origin, and a total of 5 enriched layers of dinosaur fossils were found. Some of the preserved fossils are relatively complete, mainly including the intestines, vertebrae, ischium, and humerus. Conclusions: This discovery and research have broadened the distribution range of dinosaur fossils in Yunnan, filling the gap in the absence of dinosaur fossils in the western part of the Chuxiong Basin, greatly enriching the Early Jurassic dinosaur fossil pool in Yunnan, and providing important paleontological fossil research materials for the evolution of the ancient environment and stratigraphic correlation in the western part of the Chuxiong Basin.
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Jurassic sedimentation and paleogeomorphic reconstruction in the Daqingshan area, Inner Mongolia
wangyongchao, dongshuwen, chenxuanhua, weilijuan
Abstract:
Shiguai basin is the most well-preserved Jurassic basin among the Yinshan belt, whose depositional process and detrital composition document the Jurassic geomorphic evolution of the Daqingshan area. The Lower Jurassic Wudanggou Fm. and the Middle Jurassic Zhaogou Fm. constitute the lower part of the basin fill, and record an extensional setting. During the initial rifting, southern part of the basin deposited coarse-grained alluvial fan system duo to adjacent steep topography, and gravel composition within these deposits reveals the unroofing process of proximal high-grade metamorphic terrane. The late stage of rifting was characterized by thermal subsidence, and meanwhile the flooding surface reached its maximum. During the same interval, material sourced from sedimentary rocks increased markedly in the Zhaogou Fm., indicating the ongoing deplanation and the corresponding tectonic quiescence. After then, the Late-Middle Jurassic saw an intense intraplate orogeny occurring in the Daqingshan area. This event formed the nearly E-trending Daqingshan fold-and-thrust belt which involved the southern part of the previous rifting basin into compressive deformation. However, these young structures were probably blind and their actives seemed not to cause obvious uplifting. On the contrary, basin’s northern margin denudated dramatically at the same time, as evidenced not only by the marginal deposition of the Changhangou and Daqingshan formations merely occurring in the northern part of the Shiguai basin, but also by alternative unroofing of the deep and shallow materials in the Yinshan belt. This character that the north terrane uplifted higher than the south, could be attributed to the reactivation of regional faults beside the Yinshan belt, and also can be considered as remote response to the Late Mesozoic multi-plate convergence in East Asia.
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Spatial Distribution characteristics and Influencing Factors of Geological culture villages (or towns) in China
Abstract:
Geological culture villages (or towns) are important windows for science and technology to popularize geological culture, as well as carriers for developing villages and towns. The study of their spatial distribution characteristics and influencing factors is of great significance to the further evaluation and sustainable development of geological culture villages (or towns) in China. the spatial distribution characteristics of 50 geological culture villages (or towns) in China and their influencing factors are studied by using the methods of the nearest neighbor index, geographic concentration index, kernel density analysis method and geographic detector, etc. The study shows that: (1) the spatial distribution of geological culture villages (or towns) in China presents a random situation; the regional distribution shows the unbalanced trend of "more in the east and less in the west". (2) The spatial distribution density of geological culture villages (or towns) has a significant spatial difference, with the Yangtze River Delta region as the core area of high density, the northern coastal region and the eastern region of China are the sub-high density concentration areas, and there is an extended belt running through "Shanxi-Henan-Hubei-Hunan"; (3) The factors affecting the spatial distribution pattern of geological culture villages (or towns) are composed of three primary indicators: characteristic geological resources, natural conditions, and socio-economic and human resources, among which natural conditions and socio-economic and human resources have the greatest influence on the spatial distribution of geological culture villages (or towns) and have significant effects. In the process of evaluating and constructing geological culture villages (or towns) in the future, we should strengthen the survey of geological relics in each provincial regions to optimize the spatial layout of geological culture villages (or towns); speed up the evaluation of geological culture villages (or towns) in the central and western regions to drive the economic development of less developed regions; increase the investment of funds in the central and western regions and give policy inclination to promote the coordinated development of geological culture villages (or towns) in the country.
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Study on the Sedimentary Tectonic Response of the Middle-Late Permian in the Northern Edge of Bogeda mountain
LU zhishuai, XIE qingbin, ZHANG jinning, QI liqi, XU tao, CHEN jia, XIANG honghan
Abstract:
The northern edge of Bogeda Mountain is the key part of Junggar Basin and Tianshan orogenic belt, thus it is also the key area to study the basin relationship. Middle-Late Permian tectonic and deposition evolution still remain controversial. In this study, we combined sedimentological and geophysical methods such as field observation, microscopic identification of rock slices, granularity analysis experiment and seismic data analysis, to study Sedimentary types and evolution, Deformation and development characteristics of basin structure, and sedimentary tectonic response of Jingzigou section and Dalongkou section which in the east and west Bogeda Mountain. The research results indicate that the Middle Permian Wulabo Formation to Hongyanchi Formation were lacustrine facies deposition, while the Upper Quanzijie Formation was alluvial fan-fluvial facies deposition, and the Upper Guodikeng and Wutonggou Formation were shore-shallow lacustrine-delta facies deposition .There are two main structural layers in the study area, the lower structural layer is extensional fault depression as the main geological structure, and the upper structural layer is foreland thrust as the main structural deformation. Multiple phases of tectonic activities control the sedimentary evolution process of Permian Bogeda area. Under the background of compressional structure, the Middle Permian lacustrine facies deposition became the Upper Permian alluvial fan-fluvial facies deposition.And the tectonic activity became stable later, and the sedimentary facies turned to shore-shallow lacustrine-delta facies.
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Characteristics and comprehensive evaluation of important geoheritages in Hainan Tropical Rainforest National Park
Lü Zhaoying, Xue Guicheng, He Yusheng, Wei Changxin, Lin Yihua, Hu Zailong, YUAN Qinmin, Lü Changyan, HUANG Wuxuan, Wang Chao, Lin Di, Chang Zhenyu, Zhang Zhizhuan
Abstract:
The geoheritage resources in Hainan Tropical Rainforest National Park are extremely important components of the natural resources and natural environment in the tropical rainforest. The geological environment of the geoheritage is fundamental to the biodiversity of the tropical rainforest. The scientific protection and rational utilization of geoheritage resources is one of the important contents of the construction of Hainan Tropical Rainforest National Park. Based on the comprehensive and systematic investigation and evaluation of geoheritage resources in Hainan Tropical Rainforest National Park, according to the specification for geoheritage investigation (DZ/T 0303-2017), this paper systematically summarizes the characteristics and distribution of important geoheritage resources in Hainan Tropical Rainforest National Park, and conducts a qualitative and quantitative comprehensive evaluation and classification of their scientific and aesthetic values. The research results show that there are various types of geoheritage in Hainan Tropical Rainforest National Park, with the main categories being fundamental geology and geomorphological landscape, including 4 categories: important fossil production area, important fossil origin category, rock and soil geomorphology, water geomorphology and volcanic geomorphology, and 6 subclasses: Paleobiota Fossil Site, Carbonate Rock Landform, Intrusive Rock Landform, Detrital Rock Landform, Waterfall, and Volcanic Rock Landform, with a total of 21 important geoheritage sites. Among them, there is 1 world-level geoheritage site, 17 provincial-level geoheritage sites, and 3 sub-provincial-level geoheritage sites. Through the evaluation of geoheritage sites in Hainan Tropical Rainforest National Geopark, it provides basic information and ideas for the protection and utilization of geoheritage resources in the National Park.
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2013,59(6):1097-1109, DOI:
Abstract:
There are no efforts have been made for the classification of internal wave and internal tide deposits for more than twenty years since they were discovered in the geological records. Here we try to propose a classification of internal wave and internal tide deposits based on the types which were already discovered in sedimentary rocks as well as the breaking processes of internal waves and its development research in physical oceanography. There are nine types through three orders, which include barotropic internal tide deposits, baroclinic internal tide deposits, barotropic short period internal wave deposits, baroclinic short period internal wave deposits, contour currents interaction internal wave deposits, low density turbidity currents interaction internal wave deposits, long period internal wave interaction deposits, standing internal wave deposits and other internal wave interaction deposits. The discovering internal wave and internal tide deposits in geological records are attributed into barotropic internal tide deposits, barotropic short period internal wave deposits and long period internal wave interaction deposits. And the other six types are still unrecognized. The classification proposed here perhaps give a reason for the phenomena that internal waves occur nearly ubiquitously in oceans yet their sedimentary records remain largely unrecognized. Furthermore, this classification is help for connecting the deposits of internal waves not only with its research in physical oceanography, but also with the oceanic unexpected events, ocean circulation and astronomical period in geological history.
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丁一, 李智武, 冯逢, 翟中华, 孙玮, 汤聪, 张葳, 张长俊, 刘树根
2013,59(2):389-400, DOI:
Abstract:
The Daanzhai Member of the Lower Jurassic Ziliujing Formation is one of the major oil production horizons in Sichuan Basin, where "pure" limestone from high energy shelly shoal of shallow lake facies has been usually viewed as the only kind of reservoir rock in previous studies. Based on outcrop surveying and borehole core observation as well as thin section and SEM (scanning electron microscopy) analyses, we propose in the paper that the Daanzhai Member of Ziliujing Formation is a typical lacustrine depositional sequence of mixed siliciclastic—carbonate sediments in Longgang area, central Sichuan Basin, which contains two levels of implication. In narrow sense, the mixed siliciclastic—carbonate rock means mixing of major lacustrine carbonate with minor terrigenous clastics and/or clay in various proportion. Main rock types consist of shelly limestone, sandy/silty/argillaceous shelly carbonate, calcareous shelly sandstone/siltstone/mudstone/shale, etc. In broad sense, the mixed depositional sequence implies alternating layers of shelly limestone, mudstone/shale, sandstone/siltstone and mixed siliciclastic—carbonate rock with unequal thicknesses. In general, there are three ways of mixing: punctuated mixing, in situ mixing and facies mixing, which are respectively controlled by storm wave action, hydrodynamic condition and predominant facies. Both relatively pure shelly limestone and mixed siliciclastic—carbonate rocks are extremely tight. Almost all primary porosity has disappeared because of intense compaction since burial. The present pore spaces are largely composed of dissolution pore, dissolution micropore, microfracture and structural fracture, etc. In addition to "pure" shelly limestone, some silty/argillaceous shelly limestone and shelly siltstone/mudstone/shale with relatively good porosity and permeability could also serve as one kind of effective reservoir due to better developed microfractures within them. These observations and drilling results imply that the silty/argillaceous shelly limestone of low energy shelly shoal and surrounding shelly siltstone/mudstone/shale adjacent to hydrocarbon generating center are extensively developed and potential reservoir. This is particularly important for tight oil exploration, which should be paid special attention to. Therefore, a pilot exploration is recommended to be carried out.
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2014,60(4):851-857, DOI:
Abstract:
The Laos’s salt bearing Basin was located in the southeast of new Tethys domain during Cretaceous and hosted huge potash deposit during late Cretaceous. δ34SV CDT of anhydrite from borehole of Thakhek basin located in the southeastern Vientiane with value of 13.8‰~15.3‰ is similar to that of contemporaneous marine evaporites that indicated these anhydrites were with marine origin. These evidences further prove that the potassium materials in both the Laos’s salt bearing basin sourced from Cretaceous seawater with the mixture of fresh water from land. Combining with the update data that the time of potash deposition in both the Laos’s salt bearing basin and Simao basin was approximated and sulfur isotopic composition of Mengyejing Formation，we inferred that the sulfur isotopic composition in both the Laos’s salt bearing basin and Simao basin were consistent with that of contemporaneous sea water and proposed a preliminary scenario that the two basins were possibly connected when marine transgression happened.
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2005,51(6):681-693, DOI:
Abstract:
According to the concept of ophiolite in 1 970s，exposure of marie—ultramafic rocks in the orogenic zone hasbeen interpreted to represent the relic of fossil ocean lithosphere based on its lithology units consisting withoceanic crust and upper mantle．So the ophiolite is a key e．vidence of boundary between the fossil plates，and hasbeen played an im portant role on the formulation and advancement of the plate tectonic theory． Recently，ophiolite is divided into M OR—and SSZ—types based on the formation tectonic setting． M OR-type ophioliteformed at Mid—ocean ridges(M oR)，and SSZ—type ophiolite formed on the supra—subduction zone caused bythe ocean—continent subduction or intra—ocean subduction．and there are obvious difference in mantle sequence，cumulated assem blage and lavas in petrology， mineralogy and geochemistry between M OR— and SSZ—typeophiolites．This classification explains well the various ophiolites and the difference between the ophiolite andoceanic lithosphere．During the subduction of oceanic lithosphere，the M OR—type ophiolite was subducted，or ispreserved only as dismembered thrust sheets or blocks in ophiolitic m61ange，while SSZ—type ophiolite，asfragments of modified oceanic or rebirth lithosphere caused by fossil oceanic plate subduction，is commonlypreserved in the orogenic zone due to it formed above subduction zone．Therefore，SSZ-type ophiolite is majorone preserved well in the orogenic zone．Also discussed in this paper are the problems in the ophiolite study，such as the difference between the ophiolite and ocean lithosphere in peridotites．and the methods to solve theseproblems． And the pre—Rodinia super—continent ophiolite record is still considered poorly understanding，andwhether Archean greenstone is ophiolite or not．These are all questions to answer．
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2014,60(1):1-21, DOI:
Abstract:
Based on geophysical investigations of worldwide crust and upper mantle, this paper analyzes ocean—continent transition process and lithospheric thickening process. The ocean—continent transition process contains five stages: ① crustal thickening during co expansion of an ocean, ② trench formation of and early subduction, ③ mature subduction and formation of trench—arc—basin belts, ④ convergence and migration of subduction zones, and ⑤ island—continent collision and connection to a continent. Geophysical profiles show that the crustal thickening during co expansion occurs in passive continental margins, sedimentation, magma underplating and ultra pressure hydraulic fracturing resulting in formation of trenches. After formation of trenches the passive continental margins become active, tectonic mechanics tends to subduction. In the mature subduction stage the expansion of ocean basins keeps compensation with the crustal shortening of the subduction, while opening of back arc basins or marginal seas indicates the mature subduction stage. During the post mature subduction stage, marginal sea micro plates are narrowing and subduction zones are convergence and migrating. Crowded and short subduction zones with different subduction directions can cause local extension basins, they all mix together. As crustal thickening and gravity equilibrium go on, the arc belts would uplift and finally connecting to a continent via island—continent collision, becoming a special unit of continental lithosphere, i.e. the phanerozoic eon ocean—continent zone.
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SHU Liangshu, ZHOU Xinmin, DENG Ping, YU Xinqi
2006,52(2):251-265, DOI:
Abstract:
南岭构造带发育在强烈褶皱变形的基底之上，发育了华南地区最大规模的早中生代花岗岩和裂谷盆地。基底由变质的新元古代一奥陶纪复理石一火山岩系和未变质的晚泥盆世一早三叠世沉积岩系所组成。与南岭带构造演化关系最为密切的区域断裂带有萍乡一桂林、龙岩一海丰、赣江等5条，制约着中、新生代岩体和盆地的分布、规模和产状。无论是物质来源还是形成与演化的动力学背景，南岭构造带均离不开其北面的大别造山带和南西面的印度支那造山带。南岭地区存在3条近东西方向的花岗质岩带，严格受深部构造制约，岩体常受褶皱和断裂构造控制。3个花岗岩带中的岩体时代，具有横向上北老南新、走向上西老东新、朝大洋方向年轻化的迁移演化规律，中生代东西向的花岗岩带是在古特提斯构造域近东西向的断裂带基础上发育的，岩浆热隆伸展构造和变质核杂岩多数发育在两组大断裂的交汇处。在研究区厘定出3种基本盆地类型，晚三叠世-早侏罗世发育类前陆盆地，中侏罗世发育裂谷盆地，早白垩世属火山-沉积断陷盆地，晚白垩世以来则几乎全是箕状断陷盆地。前中侏罗世盆地构造主要受特提斯构造域和印支期碰撞的影响，晚侏罗世以来盆地构造则主要受太平洋构造作用和陆内深部构造的联合制约。武夷山是晚中生代的古地理与气候分隔带；赣江带是晚中生代的火山岩界线；闽西-赣南-粤东地区存在一个近东西向的中侏罗世陆内裂谷带。区内存在3种盆一岭耦合类型：挤压逆冲型（少量）、走滑剪切型（少量）和伸展拆离型（大量）。中、新生代盆地构造和花岗岩山岭有着密切的时空与成因联系，共同构成了华南盆岭构造体系。最后对前中生代构造作用、印支期构造事件、两种构造体制的转换等问题进行了探讨。晚泥盆世-中三叠世研究区为浅海-滨海环境，几乎没有岩浆活动，龙潭期曾区域抬升为陆，地质事实不支持华南东部存在晚古生代深海洋盆的观点；南岭地区J2和J3之交形成的两类不同力学性质、岩石组合、应力场特征的盆地构造，是特提斯向太平洋构造域转变的宏观标志；南岭东段是这两种构造体制叠置和转换的重要位置之一。
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王杰, 任军平, 何胜飞, 许康康, 刘晓阳, 左立波, 孙凯, 龚鹏辉, 贺福清
2014,60(5):997-1008, DOI:
Abstract:
South Africa is one of the countries with the richest gold ore resources in the world.The gold deposits mainly occur in the northeast of the South Africa.Three types of gold ores have been recognized,which are: ① Witwatersrand conglomerate type gold deposits; ② granite greenstone belt type gold deposits; and ③ dolomite type gold deposits,with the former two types being the major ones in the region. Witwatersrand conglomerate type gold deposits are high grade,maximum deposits yield, large scale and very depth and are the most important types in South Africa.The genesis of the deposits is controversial.Two different models occur which include placer mode and thermal fluid model.According to the current data the writers think they represent two different mineralization stages. Granite greenstone belt type gold deposits mainly occur in the Barberton area which are large scale, easy mining and other characteristics, therefore which occupies an important position in the South African. The deposits are mainly hosted in quartz veins or shear zones. Three different models occur which include volcanogenic mineralisation models, inverted decollements modes and structure intersection model.
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2013,59(6):1131-1142, DOI:
Abstract:
A suit of metamorphic rock series are largely outcropped in Geyading—Maoding area, Jinsha Suture, northwestern Yunnan Province. The rocks include quartzite, sericite—quartz schist,amphibolites, mica schist and marbles. The depositional age of the metamorphic rock series has long been debated. In this paper, sericite—quartz schist and quartzite are measured by the LA MC ICP MS method. The dating of zircons shows that the detrital zircon ages of sericite—quartz have a youngest age of about 205 Ma, a dominant peak at 231 Ma, two subordinate peaks at 214 Ma and 255 Ma, and some lesser peaks at 420 Ma, 502 Ma, 873 Ma, 1.94 Ga and 2.46 Ga; the detrital zircon ages of quartzite have a youngest age of about 332 Ma, a dominant peak at 361 Ma, a subordinate peak at 422 Ma, and the other lesser peaks at 1.40 Ga, 1.56 Ga, 1.72 Ga. These dating results above suggest the protolith of sericite—quartz schist was deposited in the Late Triassic (later than 205 Ma), and the protolith of quartzite was deposited in the Early Carboniferous (later than 332 Ma), which indicate the formation age of the metamorphic rock basement in Geyading—Maoding area, Jinsha Suture, shouldn't be thought to be Proterozoic in age. Besides, the data of detrital zircon population suggest that the provenance of the metamorphic rock series was mainly derived from the Yangtz Block materials.
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WANG Zhaobo, BIAN Qing, LI Dapeng, WANG Jinyu, LIU Cailing, GUO Qipeng
2017,63(1):134-142, DOI:
Abstract:
In this paper, the characteristics of the Quaternary glacial moraine and related relics found in Mount Mengshan, Shandong Province, are systematically introduced. The authors concentrate mainly on the moraines, scratches, polished surface and chatter marks distributed in Lanxi valley. At the same time, the distribution, size, composition and rock characteristics of the lateral moraines and felsenmeers are reported. Based on the distribution of the lateral moraine and the weathering degree of gravels, we are trying to identify the moraine traces as the product formed at the last glacial period. Based on measurement and statistical analysis of the scratches on the polished bedrock surface from both sides of the valley, the length/width ratio of scratches on valley walls is about 10:1. Using lateral moraine maximum height method and investigation with lateral moraine at Mount Mengshan region, we have estimated the height of the last glaciation snow line in the southern slope of Mount Mengshan. It is about 700 meters.
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DENG Jinfu, FENG Yanfang, DI Yongjun, LIU Cui, XIAO Qinghui, SU Shangguo, ZHAO Guochun, MENG Fei, CHE Rufeng
2015,61(6):1211-1224, DOI:
Abstract:
For a long time a lot of the models about the tectonic evolution and the orogenic architecture of the Paleo Asian tectonic domain are suggested by many famous geologists. However, there are large divergence of the views, especially about both the space distribution and the closing time of the Paleo Asian Ocean. Based on the intrusive tectonic map of China with the scale of 1:2500, 000, by this paper we would like to join the discussion. (1) The formation of the intrusive arc, and the collisional as well as the postorogenic igneous petrotectonic assemblages is occurred progressively younger from west to east with time, and the trend lines of the main tectonic zones is developed from near east—west in the west to near north—south directions in the east, both of which is suggested the transition of the Paleo Asian Ocean closing to development of the Pacific tectonic domain. (2) The broad trench—arc—basin system developed at the southern margin of the Siberia craton situated in the north of the main oceanic basin; the passive continental margin at the west, and the narrow trench—arc—basin system in the middle, as well as the active continental margin at the east, respectively, developed at the northern margin of the Tarim—North China craton. (3) Both the remnant arc and the oφ since Pt3 is scattered within the main arc, and is regarded as the basement beneath the main arc. (4) The classical “massif” in the orogenic zone is considered to be the remnant arc by this paper, because they are intrusive arc formed in the early stage during the oceanic subduction. (5) The main oceanic basin is recognized from three signs by this paper, （a) The closing of the ocean is latest, （b) The oceanic subduction is bidirectional when the active arc at both the sides, or is developed at one side when one side is active continental margin, and the other side is passive continental margin, （c) The long live and the residue ocean of the Mediterranean sea type are developed as the early stage of the continent—continent collision. (6) A lot of both the intrusive arcs and the oφ during Pt3—T support the formation of the large amount of the juvenile continental crust by Sngor et al., as well as is corresponded to the positive value of the εNd(t) for the granites, which, in turn, is suggested to be formation of the large amount of the oceanic subduction resulted in the cooling of the mantle, and the adding eclogites into the mantle, finally, the high density mantle flow is formed as the dynamic source for the closing of the Paleo Asian Ocean and then the collision between the Siberia and the Tarim—North—China cratons.
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HAO Yanli 1), ZHANG Zhaochong 1, 2), WANG Fusheng 1), John J. MAHONEY 3) 1) Institute of Geology, Chinese Academy of Geological Sciences, Beijing, 100037 2) China University of Geosciences, Beijing, 100083 3) School of Ocean, Earth Science, Technology, University of Hawaii, Honolulu, HI 96822, USA
2004,50(6):587-592, DOI:
Abstract:
Analyses of basalts from the Emeishan large igneous province show that the TiO 2 contents of them are variable continuously. And outcrops of high Ti and low Ti basalts in field are unzoned spatiotemporally. The similar Sr, Nd and Pb isotopic compositions of these two types of basalts indicate that they are comagmatic igneous rocks. The MgO versus TiO 2 diagram for picrites and basalts shows four evolution trends, whose geneses were simulated by the fractional crystallization model. The result suggests that high Ti and low Ti basalts are different products of the same parent magma (picritic basaltic magma) through fractional crystallization of different minerals.
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2013,59(6):1165-1176, DOI:
Abstract:
The carbonate rocks are widely distributed, whose thermal evolution is generally high and organic matter abundance are lower in China. Whether or not they can be effective source rocks has great significance for the evaluation of hydrocarbon generation potential and exploration prospect of carbonate rocks. Many studies show that as the depth or thermal evolution degree increase, TOC of source rocks decreases, and hydrocarbon generation potential and residual amount increase and then decrease, besides the results of thermal simulation experiment, which indicate the source rocks of low organic matter abundance could can generate and expulse a great number of hydrocarbon. Hydrocarbon sources of some typical oil and gas fields are the carbonate rocks of low organic matter abundance in the world. A few factors could be considered to determine the lower limit of TOC of carbonate source rocks. The analysis suggests the lower limit of TOC of carbonate source rocks is less than 0.5% of mud rocks. The lower limit of TOC of the effective source rocks with different maturity was gained by the method of hydrocarbon generation potential and simulative calculation based on material balance principle according to the hydrocarbon expulsion threshold. Referring to the study results of predecessors and exploration practice, The lower limit of TOC of the effective carbonate source rocks with low maturity, maturity and high—over maturity stages respectively are TOC≥1.4%, TOC=0.1%~1.4% and TOC＜0.1%.
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2016,62(3):693-708, DOI:
Abstract:
As the natural barriers of Beijing and the important junctions connecting Hebei, Shanxi and Inner Mongolia, the Western Hills of Beijing have rich natural resources such as high quality coal and building materials. The Western Hills have been the energy base and important religious holy land of Beijing since 1421 AD, when Beijing was made the capital of the Ming Dynasty. A well developed ancient road system was built for the purpose of connecting the important military facilities, temples, coal mines and hundreds of villages in Ming and Qing Dynasties. A lot of hoof shaped holes with diameters of about 20 cm are scattered along the surface of the manmade ancient roads, which are dozens meters or hundreds of meters higher than the river bed. Typically the holes show clear patterns of animal trails, the distance between two holes averages 40~60 cm. Based on this analysis, the author validated that these holes could not be formed by the processes of grinding action of streams currents to make pot holes nor by differential erosion. They are the stepping holes which were formed by the continuous treading of the hoof shoes of pack animals.
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2014,60(2):237-259, DOI:
Abstract:
Based on geophysical lithospheric investigations worldwide, this paper analyzes the continental collision orogenic process. The geophysical lithospheric investigation data as well as physical laws build the foundation for reconstruction of evolution and the deconstruction method for interpretation of deep reflection profiles. Continental collision results in accretion of continents from the ocean—continent transition (OCT) zones. Owing to widely development of the OCT zones, the Alps—Xizang(Tibet) collision orogenic belt belongs to the so called skirt plate collision type, which does not act like elastic collision with no rebounding effects. This type collision usually shows ophiolite but few ultrahigh metamorphic belts on the surface. On the other hand, owing to rarely development of the OCT zones, the Dabie—Sulu collision orogenic belt belongs to the so called nude plate collision type, which acts like elastic collision with rebounding effects. This type collision usually shows ultrahigh pressure metamorphic belts but few ophiolite on the surface. The rebound created conditions for exhumation of the ultrahigh pressure metamorphic belts from deep mantle. Both the skirt plate and nude plate collisions contains mainly four collision stages: (1) pre collision stage involving ocean subduction and closing, (2) pre collision stage, (3) late collision stage or continental to continental subduction stage, and (4) post orogeny stage. At the pre collision stage, the skirt plate collision do not rebound but the nude plate collision does. At the late collision stage, the skirt plate collision does not show the exhumation of the ultrahigh pressure metamorphic belts but the nude plate collision does. The post orogeny stage means gradually stopping the orogeny process, lithospheric stress between continents in collision transfers to extension state from compressional state, resulting the same rotational pore between the two continents. However, lithospheric deformation and detachment can still occur, and convergence of deep heat fluids and magma intrusions would prefer play important roles in the week lithosphere along the collision belts.
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2013,59(6):1143-1149, DOI:
Abstract:
The barite deposits hosted in Early Cambrian black shales in South China is one of the representative world famous sediment hosted stratiform deposits. This paper reports the discovery of zoned hyalophane for the first time, based on a case study in the Dahebian barite deposits, Tianzhu county, South China. Analytical results of electron microprobe analysis show that outer BaO content is 1653% to 1786% and K2O content is 777% to 819%, while BaO content is 1204% to 1421% and K2O content is from 860% to 979% in the core. Combined with the geological setting and previous research results, we addressed geological implications of this discovery. It supports the impact of hydrothermal liquid in the formation of the barite deposit. Multiple stages of barium rich fluid participated in the barite formation, and the mineralization was fault controlled, episodic and progressive. This not only further implies the hydrothermal sedimentary genesis of the deposit, but also betters the understanding of mineralization process. These results may have general implications to the other studies worldwide, as the Dahebian deposit is the biggest in volume of such deposits in the world.
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2013,59(6):1177-1188, DOI:
Abstract:
Landslide inventory is the essential part of regional earthquake triggered landslide studies. In recent years, studies about landslide inventory related with single seismic event are common. However, area and volume error analysis of inventory of landslides triggered by earthquake is still lack. In this paper, a remote sensing image resolution based error analysis method of inventory of landslides triggered by earthquake was proposed. Error analysis of inventory of 2036 landslides triggered by the April 14, 2010 Mw 69 Yushu earthquake, inventory of 30828 landslides triggered by the January 12, 2010 Mw 70 Haiti earthquake, and inventory of 197481 landslides triggered by the May 12, 2008 Mw 79 Wenchuan earthquake were carried out respectively. The results show that area of the Yushu earthquake triggered landslides is 1191 km2, of range from 1153 km2 to 1229 km2, which is error range from 9681% to 10319%; these landslides in a total volume of 2012×106m3, of range from 1947×106m3 to 2078×106m3, in other words, error range from 9677% to 10328%. Area of the Haiti earthquake triggered landslides is 15743 km2, of range from 15118 km2 to 16368 km2, which is error range from 9603% to 10397%; these landslides in a total volume of 29698×106m3, of range from 28594×106m3 to 30821×106m3, in other words, error range from 9628% to 10378%. Area of the Wenchuan earthquake triggered landslides is 1160025 km2, of range from 1072258 km2 to 1248424 km2, which is error range from 9243% to 10762%; these landslides in a total volume of 4693159×106m3, of range from 4372957×106m3 to 5033739×106m3, in other words, error range from 9318% to 10726%. The relation between resolution of the remote sensing and landslide inventory error show that the remote sensing resolution affects on landslide inventory error significantly. Also, the correlation of earthquake landslide frequency distribution and landslide inventory error show that there was a significant effect on landslide inventory error for earthquake landslide frequency distribution. This method of earthquake triggered landslide inventory error analysis can be applied to other more regional earthquake triggered landslides events.
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2012,58(1):91-104, DOI:
Abstract:
The Eocene—Oligocene climate transition (EOCT) was a period of rapid global cooling at abou 34 Ma ago, representing a major step from early Cenozoic greenhouse toward modern icehouse conditions. It was accompanied by a series of dramatic changes in Earth's environmental system, including an expansion of ice sheets on the Antarctic continent, a global sea level drop, a declining atmospheric CO2 concentration, a deepening of the calcite compensation depth, and a biotic reorganization, thus has great significance in understanding the mechanisms behind the long term Cenozoic cooling, the behavior of regional climate in response to rapid cooling and the effects of major climatic changes on the biotic reorganization. This review summarizes recent progress in studying EOCT. (1) Significant cooling during this transition inferred from geological records of different latitudes indicates this phenomenon was triggered by global rather than regional factors. (2) The declining of atmospheric CO2 and the associated global carbon cycle changes have been proved as the primary causes of EOCT by modeling studies, rather than the previous hypothesis that the Antarctica was thermally isolated by the initiation of Antarctic Circumpolar Current. (3) Marine records revealed that this transition is marked by a two step increase of benthic foraminiferal oxygen isotope values occurred within 400~500 ka, reflecting the drop of global temperature and establishment of Antarctic ice sheets, respectively. (4) A comparison of the EOCT interval in Asian terrestrial records with marine records suggests that the regional aridification mainly corresponds to atmospheric cooling (i.e., the first step of EOCT) rather than ice volume growth. However, there are still many questions remained unsolved. Future application of more detailed and accurate proxies of atmospheric CO2 and paleotemperature, recovery of high resolution sediment archives from the oceans and continents and more complex models across the EOCT will further reveal the changes of each environmental factor during this transition and their relationship with each other, and obtain a thorough understanding of the mechanisms behind this critical climate transition.
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何付兵, 徐吉祥, 谷晓丹, 程新彬, 魏波, 李昭, 梁亚南, 王泽龙, 黄淇
2013,59(6):1150-1164, DOI:
Abstract:
Amuguleng granite is located at the north of East Ujimqin Banner（Dong Ujimqin Qi） Administration Center in Inner Mongolia. Geological investigation indicates that the granite composing of 2 intrusive rocks: gray yellow medium—fine, medium—coarse grained adamellite containing huge phenocryst and gray white fine adamellite. Zircon U Pb age of the granite dated as 314.2±2.2Ma and 167.1±1.3Ma, suggesting that they were products of magmatic evolution during Late Carboniferous and Middle Late Jurassic respectively. Accessory minerals of both the two granites are rich in magnetite, monazite, and sphene, and there is fluorite in the Mid-Late Jurassic granite. Compositon of the rocks indicates that these two kinds of granites have similar geochemical characteristics: major element are characterized by enrichment of Si, higher DI and NK/A , Fe2O/FeO ratios. The race element spider diagram indicates that granites are relatively rich in Rb, Th, U,Pb, slightly enriched in the light rare earth elements La,Ce, and depleted in high field strength elements such as Nb, Ba and Sr, Ti; While the distribution model of REE is right oblique, which is relatively LREE enriched and HREE depleted, and the HREE curve is flat. Based on the results, these two kinds of granites are attributed to high differentiated metaluminous—weakly peraluminous high K calc alkaline series, which are the typical I type granites. The source materials might come from younger crustal felsic rocks with high K and normal water content, And the source material of felsic continental rocks of late Carboniferous granite unit is mixed with mantle derived basaltic components. The Middle Late Jurassic granitic magma maybe originated from the remelting or the partial remelting of Late Carboniferous granite, at least, it has similar magma source with that of the Late Carboniferous granite. The Late Carboniferous granite unit was formed in compression setting at the late syn collision stage of Central Asian Orogeny. The Middle Late Jurassic granite unit was formed in the extension environment setting, while the geotectonic background was changing from Mongolia—Ochotsk ocean system into the Paleo pacific tectonic dynamic systems.
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2021,67(5):1197-1206, DOI: 10.16509/j.georeview.2021.08.013
Abstract:
Yoredale cycle,including limestone,coal seam and terrigenous clastic rock,is characterized by direct sedimentary contact between coal seam roof and marine limestone.Previous studies have given several completely different causes for this cycle.In order to explore the real formation mechanism of the cycle,the sedimentary characteristics of coal accumulation period in geological history are compared with the sedimentary regularities of modern vegetation, peat—swamp and carbonate rock.The analysis results show that the plants were extremely prosperous in the coal accumulation period of geological history,and dominated the basin evolution stage.Under the confinement of advance vegetation,extremely less terrigenous debris input into the basin,forming a dynamic peat—swamp.After the peat—swamp is covered by water,even shallow water is very clear.The formation of limestone is promoted by the interaction of aquatic organisms with the deposited organic matter,and the subsequent diagenesis cementation.From the top of the coal seam to the bottom of the limestone,it represents the littoral without detrital input, forming a sedimentary sequence with gradually increasing water depth.Limestone and underlying coal seam are continuous deposition.The formation of Yoredale cycle is due to the limitation of terrigenous clastic input by advance vegetation,which leads to clear and normal transgressive and regressive sediments.Although the thickness of limestone and coal seam is not very large,the lateral continuity is good.The coal seam thickens and the limestone thins in the direction of terrigenous source,while the coal seam thins and the limestone thickens in the direction of sea.Thick coal seam can be formed in the continental direction of the Yoredale cycle.The discovery of the truth of Yoredale cycle has laid a solid foundation for the study of sedimentary paleogeography and sequence stratigraphy,as well as accurate regional correlation and exploration of coal accumulation regularity.
