Chief Editor:HOU Zengqian
Governing Body:China Association for Science and Technology
Organizer:Geological Society of China
start publication :1922
ISSN:ISSN 1000-9515
CN:CN 11-2001/P
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2017, 91(6):0-Ⅰ.
Abstract:
热烈祝贺《地质学报》英文版编委杨经绥、张宏福、徐义刚、戴民汉、邵明安新当选为年中国科学院院士,毛景文新当选为年中国工程院院士。 热烈祝贺《地质学报》中文版编委侯增谦新当选为年中国科学院院士。
2017, 91(6):0-1.
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2017, 91(6):1-1.
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2017, 91(6):Ⅰ-Ⅰ.
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WANG Chenglong , ZHANG Meisheng , LI Xiaobo , WANG Yini
2017, 91(6):1949-1963.
Abstract:The pollen and spores found in the Early Cretaceous strata of two cores from the Shuangliao Fault Depression were studied systematically, and two palynological assemblages have been recognized. Assemblage I from the Yingcheng Formation is named Paleoconiferus-Pinuspollenites; the assemblage is characterized by an extremely high content of Paleoconifer pollen. Assemblage II from Member 1 of the Denglouku Formation is named Cicatricosisporites-Cyathidites-Pinuspollenites; the assemblage is characterized by the abundant presence of Laevigati spores, but less Paleoconifer pollen. According to the palynological data and zircon U-Pb dating, the geological age of the Yingcheng Formation is thought to be Aptian-Albian, and that of the Denglouku Formation is thought to be Early Albian. On the basis of the composition of each assemblage, we can infer that during the depositional period of the Yingcheng Formation, the paleovegetation was mainly conifer forest, the paleoclimate was consistent with the temperate climate of today, and the paleoenvironment was humid feature. During the depositional period of Member 1 of the Denglouku Formation, the paleovegetation was mainly conifer forest and shrubs, the paleoclimate was consistent with the subtropical climate of today, and the paleoenvironment was humid. The results significantly improve our understanding of the stratigraphy in the Shuangliao Fault Depression, provide biostratigraphic evidence for the division and correlation of Early Cretaceous strata in the Shuangliao Fault Depression, and provide new data for analyzing paleovegetation and paleoclimate in the Songliao Basin.
WANG Tianyang , LI Guobiao , LI Xinfa , NIU Xiaolu
2017, 91(6):1964-1977.
Abstract:This is a new report on the early Eocene radiolarian fauna from the Sangdanlin section in the Gyirong region, along the southern margin of the Yarlung Zangbo Suture Zone. The Sangdanlin section measured in this study is divided into three lithostratigraphic units from bottom to top: the Zongzhuo, Sangdanlin, and Zheya formations. Abundant radiolarian fossils were obtained from the Sangdanlin section and 54 species of 30 genera were identified and assigned as follows: Cryptamphorella conara-C. macropora the late Cretaceous Zone and Amphisphaera coronate, Buryella tetradica-Bekoma campechensis, and B.bidartensis-B. divaricata the Paleocene-early Eocene Interval Zones. The Paleocene–early Eocene radiolarian zones are comparable to the radiolarian zones RP4-RP8 in New Zealand. Based on the data of radiolaria and lithofacies, it is suggested that the Zongzhuo Formation should be deposited along the base of the north-facing, continental slope of the Greater Indian continental margin, and the Sangdanlin Formation should be a deep marine, sedimentary sequence located in a foreland basin. The early Eocene radiolarian fauna in the Sangdanlin Formation constrains the initial age of the India-Asia collision to no later than 53.6 Ma.
TIAN Xinglei , LUO Kunli , Andrew V. ZUZA
2017, 91(6):1978-1991.
Abstract:The Ediacaran and early Cambrian black shales are widespread across the South China Craton (Yangtze and Cathaysia blocks). However, the trace element distribution patterns of the Ediacaran and early Cambrian black shales in the Cathaysia Block are still unclear. In this study, thirty-four black shale samples in the Lechangxia Group (Ediacaran) and thirteen black shale samples in the lower Bacun Group (early Cambrian) from Guangning area, western Guangdong Province, South China, were analyzed for major and trace elements concentrations. Compared to the upper continental crust, the Ediacaran black shales exhibit strongly enriched Se, Ga, and As with enrichment factor values (EF) higher than 10, significantly enriched Bi and Rb (10>EF>5), weakly enriched Mo, Ba, Cs, V, In, Be, Tl, and Th (5>EF>2), normal U, Cr, Cd, Sc, Pb, Cu, and Li (2>EF>0.5), and depleted Ni, Zn, Sr, and Co. Early Cambrian black shales display strongly enriched Se, Ga, and As, significantly enriched Ba, Bi, and Rb, weakly enriched Mo, Cs, Cd, V, U, Be, In, and Tl, normal Sc, Th, Cr, Li, Cu, Ni, and Pb and depleted Co, Zn, and Sr. Moreover, Se is the most enriched trace element in the Ediacaran and early Cambrian black shales: concentrations vary from 0.25 to 30.09 ppm and 0.54 to 5.01 ppm, and averaging 4.84 and 1.72 ppm, with average EF values of 96.87 and 34.32, for the Ediacaran and early Cambrian shales respectively. The average concentration of Se in the Ediacaran black shales is 2.8 times higher than that of early Cambrian black shales. Se contents in the Ediacaran and early Cambrian black shales exhibit significant variation (P = 0.03). Provenance analysis showed that Se contents of both the Ediacaran and early Cambrian black shales were without detrital provenance and volcanoclastic sources, but of hydrothermal origin. The deep sources of Se and the presence of pyrite may explain the higher Se contents in the Ediacaran black shales. Similar with the Se-rich characteristics of the contemporaneous black shales in the south Qingling Mountain and Yangtze block, the Ediacaran and early Cambrian black shales in Guangning area, Cathaysia, are also enriched in Se, which may provide a clue for looking for the selenium-rich resources in western Guangdong Province.
Sukanta GOSWAMI , Pradeep K. UPADHYAY , Purnajit BHATTACHARJEE , Malaiandi G. MURUGAN
2017, 91(6):1992-2006.
Abstract:Plate tectonic activity has played a critical role in the development of petrotectonic associations in the Kadiri schist belt. The calc alkaline association of basalt, andesite, dacite and rhyolite (BADR) is the signature volcanic rock suite of the convergent margin. The N-S belt has gone below the unconformity plane of Cuddapah sediments. In the northern part geochemical and structural attributes of the Kadiri greenstone belt is studied along with microscopic observations of selected samples. Harker diagram plots of major elements generally indicate a liquid line of descent from a common source, such that BADR rocks are derived from a common parent magma of basaltic to andesitic composition. These calc-alkaline volcanic rocks are formed at convergent margins where more silicic rocks represent more highly fractionated melt. All the litho-units of this greenstone belt indicate crush and strain effects. The stretched pebbles in the deformed volcanic matrix with tectonite development along with associated greenschist facies metamorphism, alteration and hydration is remarkable. Flow foliation plane with N-S strike and very low angle (5° to 10°) easterly dip and N-S axial planar schistosity formed due to later phase isoclinal folding can be clearly identified in the field. Basic intrusives are quite common in the surrounding area. All the observations including the field setting and geochemistry clearly demonstrate ocean-continent subduction as the tectonic environment of the study area.
FANG Huihuang , SANG Shuxun , WANG Jilin , LIU Shiqi , JU Wei
2017, 91(6):2007-2023.
Abstract:Study on tectonic fractures based on the inversion of tectonic stress fields is an effective method. In this study, a geological model was set up based on geological data from the Hudi Coal Mine, Qinshui Basin, a mechanical model was established under the condition of rock mechanics and geostress, and the finite element method was used to simulate the paleotectonic stress field. Based on the Griffith and Mohr-Coulomb criterion, the distribution of tectonic fractures in the Shanxi Formation during the Indosinian, Yanshanian, and Himalayan period can be predicted with the index of comprehensive rupture rate. The results show that the acting force of the Pacific Plate and the India Plate to the North China Plate formed the direction of principal stress is N-S, NW - SE, and NE - SW, respectively, in different periods in the study area. Changes in the direction and strength of the acting force led to the regional gradients of tectonic stress magnitude, which resulted in an asymmetrical distribution state of the stress conditions in different periods. It is suggested that the low-stress areas are mainly located in the fault zones and extend along the direction of the fault zones. Furthermore, the high-stress areas are located in the junction of fold belts and the binding site of multiple folds. The development of tectonic fractures was affected by the distribution of stress intensity and the tectonic position of folds and faults, which resulted in some developed areas with level I and II. There are obvious differences in the development of tectonic fractures in the fold and fault zones and the anticline and syncline structure at the same fold zones. The tectonic fractures of the Shanxi Formation during the Himalayan period are more developed than those during the Indosinian and Yanshanian period due to the superposition of the late tectonic movement to the early tectonic movement and the differences in the magnitude and direction of stress intensity.
GUO Xianqing , YAN Zhen , Jonathan C. AITCHISON , FU Changlei , WANG Zongqi
2017, 91(6):2024-2040.
Abstract:Walegen Au deposit is closely correlated with granitic intrusions of Triassic age, which are composed of granite and quartz porphyries. Both granite porphyry and quartz porphyry consist of quartz, feldspar and muscovite as primary minerals. Weakly peraluminous granite porphyry (A/CNK=1.10–1.15) is enriched in LREE, depleted in HREE with Nb-Ta-Ti anomalies, and displays subduction-related geochemistry. Quartz porphyry is strongly peraluminous (A/CNK=1.64–2.81) with highly evolved components, characterized by lower TiO2, REE contents, Mg#, K/Rb, Nb/Ta, Zr/Hf ratios and higher Rb/Sr ratios than the granite porphyry. REE patterns of quartz porphyry exhibit lanthanide tetrad effect, resulting from mineral fractionation or participation of fluids with enriched F and Cl. LA-ICP-MS zircon U-Pb dating indicates quartz porphyry formed at 233±3 Ma. The ages of relict zircons from Triassic magmatic rocks match well with the detrital zircons from regional area. In addition, εHf(t) values of Triassic magmatic zircons from the granite and quartz porphyries are ?14.2 to ?9.1 (with an exception of +4.1) and ?10.8 to ?8.6 respectively, indicating a crustal-dominant source. Regionally, numerous Middle Triassic granitoids were previously reported to be formed under the consumption of Paleotethyan Ocean. These facts indicate that the granitic porphyries from Walegen Au deposit may have been formed in the processes of the closing of Paleotethyan Ocean, which could correlate with the arc-related magmatism in the Kunlun orogen to the west and the Qinling orogen to the east.
TIAN Wei , WANG Shuangyue , LIU Fenglin , CHU Zhuyin , WANG Bin , CHEN Mimi , Jennifer PRICHARD
2017, 91(6):2041-2057.
Abstract:Tectonically emplaced peridotites from North Hebei Province, North China Craton, have retained an original harzburgite mineral assemblage of olivine (54%–58%) + orthopyroxene (40%–46%)+minor clinopyroxene (<1%)+spinel. Samples with boninite-like chemical compositions also coexist with these peridotites. The spinels within the peridotites have high-Al end-members with Al2O3 content of 30 wt%–50 wt%, typical of mantle spinels. When compared with experimentally determined melt extraction trajectories, the harzburgites display a high degree of melting and enrichment of SiO2, which is typical of cratonic mantle peridotites. The peridotites display variably enriched light rare earth elements (REEs), relatively depleted middle REEs and weakly fractionated heavy REEs, which suggest a melt extraction of over 25% in the spinel stability field. The occurrence of arc- and SSZ-type chromian spinels in the peridotites suggests that melt extraction and metasomatism occurred mostly in a subduction-related setting. This is also supported by the geochemical data of the coexisting boninite-like samples. The peridotites have 187Os/188Os ratios ranging from 0.113–0.122, which is typical of cratonic lithospheric mantle. These 187Os/188Os ratios yield model melt extraction ages (TRD) ranging from 981 Ma to 2054 Ma, which may represent the minimum estimation of the melt extraction age. The Al2O3-187Os/188Os-proxy isochron ages of 2.4 Ga–2.7 Ga suggest a mantle melt depletion age between the Late Achaean and Early Paleoproterozoic. Both the peridotites and boninite-like rocks are therefore interpreted as tectonically exhumed continental lithospheric mantle of the North China Craton, which has experienced mantle melt depletion and subduction-related mantle metasomatism during the Neoarchean- Paleoproterozoic.
LI Yun , HOU Xiaoyu , YANG Bo , ZHAO Yuanyi , CHEN Long
2017, 91(6):2058-2077.
Abstract:The Duobaoshan ore concentration area, located in Nenjiang County of Heilongjiang Province, is an important porphyry Cu-Mo ore concentration area in China, which is characterized by complex magmatic activities and multi–phase overprinting metallogenesis. On the basis of field geological observation, systematic sampling, in-lab analysis and the metallogenic regularity in the Xiang'an–Mongolian metallogenic belt, this work carried out high-precision dating and geochemical analysis on the Yuejin, 173-kilometer and Wolihedingzi rock bodies. These rock bodies are renamed monzonitic granite and their consistent age (238 Ma) show that they were formed not in Variscan but in Indosinian. Therefore, it is inferred that the ore spots formed in the potassium silicate and sericite alteration zones of the rock mass also belong to Indosinian. In addition, we collected granodiorite from the Tongshan mining pit, and its zircon age is 223.1±2.8 Ma and the Cu content of the sample is high. The Tongshan mineralization is inferred to undergo the superimposition of Indosinian diagenetic mineralization. The age of the granodiorite porphyry related to copper-molybdenum mineralization in the Xiaoduobaoshan area is 222.1±5.5 Ma, and the earlier age of granodiorite is 471.8±7.4 Ma, indicating that the initial magmatic activities belong to the Duobaoshan porphyry system in the Caledonian period. The geochemical characteristics of the Indosinian rock samples show continental arc features, with reference to tectonic-magmatic activities of the whole Daxing'anling area. We consider that the magmatic activities and mineralization of the Indosinian period are affected by the southward subduction of Okhotsk Ocean since Late Permian. By combining the mineralization rules of Daxinganling area and the structural systems of Duobaoshan ore concentration area, we divide two rock-mineralization belts in this area including the Yuejin–Duobaoshan–Tongshan belt and 173-kilometer–Xiaoduobaoshan–Wolihedingzi belt, which are distributed nearly parallel along the NW-trending fractures and show similar geotectonic settings and the timing of the magmatic activities. It is favorable for discovering porphyry Cu-Mo deposits in these two metallogenic belts, especially in the Yuejin, 173-kilometer and Wolihedingzi areas where less research work has been made.
DUAN Liu’an , GU Huangling , YANG Xiaoyong
2017, 91(6):2078-2108.
Abstract:The newly discovered Yangchongli gold deposit is a unique independent gold deposit in the Tongling ore-cluster region controlled by the tectonic alteration firstly discovered in the Lower Yangtze Metallogenic Belt (LYMB). The host magmatic rocks mainly consist of monzodiorite and K-feldspar granite. The LA-ICP-MS U-Pb zircons dating yielded weighted mean 206Pb/238U ages of 140.7 ± 1.8 Ma and 126.4 ± 1.2 Ma for the monzodiorite and K-feldspar granite, respectively. Monzodiorites are enriched in Sr, Ba, Rb, and depleted in Y, Yb with high Sr/Y and La/Yb ratios, similar to the geochemical features of adakite, considered as products of differentiation of mafic magmas originating from lithospheric mantle melt/fluids caused by metasomatism during paleo-Pacific Plate subduction in the Mesozic. In contrast, the compositions of K-feldspar granites are A-type granites, indicating an extensional tectonic background. Gold ores hosted in the fracture zone occurred as quartz vein within cataclastic rock. Sulfur and lead isotopes from pyrites show crust-mantle mixing characteristics. Metal components from strata also took part in the gold mineralization, and resulted from two episodes of magmatism that were probably related to tectonic transition from a compressive to an extensional setting between 140–126 Ma, which led to the Mesozoic large-scale polymetallic mineralization events in eastern China.
Shohreh HASSANPOUR , Mohsen MOAZZEN
2017, 91(6):2109-2125.
Abstract:The Haftcheshmeh porphyry Cu-Mo-Au deposit in the Arasbaran metallogenic belt (AMB) of NW Iran contains more than 185 Mt of ore, with a grade ranging from 0.3% to 0.4%. It is hosted within a porphyritic diorite to granodiorite intruded into an older gabbro - diorite intrusion. 40Ar/39Ar analyses of primary magmatic hornblende from the granodiorite porphyry and gabbro - diorite show plateau ages of 26.41 ± 0.59 Ma, with an inverse isochron age of 25.9 ± 1.0 Ma and a plateau age of 27.47 ± 0.17 Ma, with an inverse isochron age of 27.48 ± 0.35 Ma for these two rock types, respectively. Comparing these new age data with those from the nearby Sungun (20.69 ± 0.35 Ma) and Kighal porphyry deposits defines a northwest-southeast Cu-Mo-Au mineralization zone extending for 20 km over the time span of ~27 to 20 Ma. Geochemically, Haftcheshmeh rocks are calc-alkaline with high potassium affinities with tectonic setting in relation to volcanic arc setting. Large ion lithophile elements (LILE) such as Th, U and K show enrichment on a primitive mantle normalized diagram (specially Pb), and are depleted in high field strength elements (HFSE) such as Ti and Nb, pointing to a mantle magma source contamination with crustal materials by subducted oceanic crust.
FAN Honghai , CHEN Jinyong , WANG Shengyun , ZHAO Jingyang , GU Dazhao , MENG Yanning
2017, 91(6):2126-2137.
Abstract:This paper presents a systematic study of major and trace elements and Sm-Nd isotopes in leucogranites closely related to uranium mineralization in the Gaudeanmus area, Namibia. The results illustrate that the uraniferous leucogranites possess high SiO2 (68.8wt%–76.0wt%, average 73.1wt%) and K (4.05wt%–7.78wt%, average 5.94wt%) contents, and are sub-alkaline and metaluminous to weakly peraluminous, as reflected by A/CNK values of 0.96–1.07 with an average of 1.01. The leucogranites are rich in light rare earth elements (LREE/HREE = 2.53–7.71; (La/Yb)N = 2.14–10.40), have moderate Eu depletion and high Rb/Sr ratios (2.03–5.50 with an average of 4.36); meanwhile, they are enriched in Rb, K, Th, U and Pb, and depleted in Ba, Nb, Ta, and Sr. The εNd(t) values of uraninites range from ?14.8 to ?16.5, and the two-stage Nd model ages are 2.43–2.56 Ga. Detailed elemental and Sm-Nd isotopic geochemical characteristics suggest that the leucogranites were formed in a post-orogenic extensional environment. The U-rich pre-Damara basement was the main source of uranium during the primary mineralization event, which is disseminated in leucogranites, whereas the uranium mineralization in veins possibly resulted from remobilization of the primary uranium minerals.
LIU Zhangyue , PENG Suping , QIN Mingkuan , LIU Hongxun , HUANG Shaohua , HE Zhongbo , GUO Qiang , XU Qiang , SONG Jiye
2017, 91(6):2138-2152.
Abstract:Meso-Cenozoic intracontinental orogenic processes in the Tian Shan orogenic belt have significant effect on the sandstone-hosted uranium deposits in the intramontane basins and those adjacent to the orogen. The Sawafuqi uranium deposit, which is located in the South Tian Shan orogenic belt, is investigated to reveal the relationships between uranium mineralization and orogenies. Recent exploration results show that the Sawafuqi uranium deposit has tabular, stratiform, quasi-stratiform, and lens-like orebodies and various geological characteristics different from typical interlayer oxidation zone sandstone-hosted uranium deposits. Systematic studies of ore samples from the Sawafuqi uranium deposit using a variety of techniques, including thin section observation, α-track radiograph, electron microprobe and scanning electron microscope, suggest that uranium mineralization is closely related to pyrite and organic matter. Mineralization-related alterations in the host rocks are mainly silicification and argillation including kaolinite, illite (and illite-smectite mixed layer) and chlorite. Tree stages of mineralization were identified in the Sawafuqi uranium deposit: (i) uranium-bearing detritus and synsedimentary initial pre-enrichment; (ii) interlayer oxidization zone uranium mineralization; and (iii) vein-type uranium mineralization. The synsedimentary uranium pre-enrichment represents an early uranium enrichment in the Sawafuqi uranium deposit, and interlayer oxidation zone uranium mineralization formed the main orebodies, which are superimposed by the vein-type uranium mineralization. Combining the results of this study with previous studies on the Meso-Cenozoic orogenies of South Tian Shan, it is proposed that the synsedimentary uranium pre-enrichment of the Sawafuqi uranium deposit was caused by Triassic Tian Shan uplift, and the interlayer oxidation zone uranium mineralization occurred during the Eocence-Oligocene period, when tectonism was relatively quiet, whereas the vein-type uranium mineralization took place in relation to the strong orogeny of South Tian Shan since Miocene.
WANG Pengpeng , HU Yuzhao , LIU Lu , JIANG Xiaojun , LI Chao , Chad Joseph Bartholomew , ZHANG Guiquan
2017, 91(6):2153-2163.
Abstract:Abundant organic inclusions are present in the Qinglong antimony deposit. However, the source rocks of these organic matters have not been reliably identified. Recently, a paleo–oil reservoir was found in the Qinglong antimony deposit. In view of similar components of gaseous hydrocarbon, we propose that the organic matters observed in inclusions in Qinglong antimony deposit would come from this paleo–oil reservoir. We used the Re–Os dating method to determine the age of the bitumen from this paleo–oil reservoir, and obtained an isochron age of 254.3±2.8 Ma. The age indicates that the oil-generation from source rock occurred in the early Late Permian, earlier than the Sb mineralization age (~148±8.5 Ma) in the Qinglong antimony deposit area. After oil generation from Devonian source rock, first and secondary migration, the crude oil have probably entered into the fractures and pores of volcanic rocks and limestone and formed a paleo–oil reservoir in the western wing of Dachang anticline. As burial process deepened, the crude oil has turned into natural gas, migrates into the core of Dachang anticline and formed a paleo–gas reservoir. The hydrocarbons (including CH4) in the reservoirs can serve as reducing agent to provide the sulfur required for Sb mineralization through thermal chemical reduction of sulfates. Therefore, the formation of oil–gas in the area is a prerequisite for the Sb mineralization in the Qinglong antimony deposit.
NIE Xiao , SHEN Junfeng , LIU Haiming , DU Baisong , WANG Shuhao , LI Jie , XU Liwei , WANG Ran
2017, 91(6):2164-2179.
Abstract:The Gangcha gold deposit was discovered in 2011 in the Xiahe-Hezuo region, West Qinling Orogen, China. Five types of pyrite have been identified in the ore according to the detailed mineral paragenetic studies. Geochemical data are presented for type I pyrite (py1) rim-core zonation and for the different types of pyrite based on in-situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and electron probe microanalysis (EPMA). The results show that pyrites are characterized with heterogeneous Au concentrations, which indicate that Au occurs mainly as micro- or nano-particle native inclusions. Time-resolved depth profiles demonstrate that As, Co and Ni occur as solid solutions in pyrite, whereas Cu, Pb, Zn and Ag occur mainly as inclusions. Trace element concentrations differ between rims and cores in py1, and the differences also exist within different pyrite types. These differences indicate complex chemical evolution of the ore-forming fluids, and the overall geology, geochronology, and stable isotope and pyrite data suggest that the ore-forming fluids were closely linked to magmatic activity during the Triassic Period in West Qinling orogenic belt.
Ali AAMIR , Ullah MATEE , Hussain MATLOOB , Asher Samuel BHATTI , Rehman KHAISTA
2017, 91(6):2180-2199.
Abstract:The successful exploration and production of shale-gas resources in the United States and Canada sets a new possible solution towards the energy crisis presently affecting most countries of Asia. This study focuses on the use of well log and 2D seismic data for the characterization of the shale oil/gas potential of a Paleocene–Eocene succession — the Meyal area in the Potwar Basin of Pakistan. Two shaly plays are identified in Paleocene–Eocene strata in well logs using ΔLogR and modified ΔLogR cross-plot techniques. The results indicate that Paleocene shale (the Patala Formation) and the lower shaly part of Eocene limestone (Sakesar Formation) can be potentially mature source rocks. However, the thermal maturity modelling proves that only the Paleocene shale is mature. Our results also suggest that the maturity responses on ΔLogR models for the lower shaly part of the Eocene limestone are due to trapped hydrocarbons in the intra-formational fractures. Petroelastic/petrophysical analysis of the Patala Formation reveals two potential shale oil/gas zones on the basis of Young’s modulus, Poisson’s ratio, Brittleness index and Total Organic Content at an exploitation depth of 3980–3988 m. This work can provide valuable insight for estimating shale oil/gas potential in highly deformed basins not only in Asia but in other parts of the world.
WU Xiaoqi , LIU Quanyou , LIU Guangxiang , WANG Ping , LI Huaji , MENG Qingqiang , CHEN Yingbin , ZENG Huasheng
2017, 91(6):2200-2213.
Abstract:The molecular compositions and stable carbon and hydrogen isotopic compositions of natural gas from the Xinchang gas field in the Sichuan Basin were investigated to determine the genetic types. The natural gas is mainly composed of methane (88.99%–98.01%), and the dryness coefficient varies between 0.908 and 0.997. The gas generally displays positive alkane carbon and hydrogen isotopic series. The geochemical characteristics and gas-source correlation indicate that the gases stored in the 5th member of the Upper Triassic Xujiahe Formation are coal-type gases which are derived from source rocks in the stratum itself. The gases reservoired in the 4th member of the Xujiahe Formation and Jurassic strata in the Xinchang gas field are also coal-type gases that are derived from source rocks in the 3rd and 4th members of the Xujiahe Formation. The gases reservoired in the 2nd member of the Upper Triassic Xujiahe Formation are mainly coal-type gases with small amounts of oil-type gas that is derived from source rocks in the stratum itself. This is accompanied by a small amount of contribution brought by source rocks in the Upper Triassic Ma’antang and Xiaotangzi formations. The gases reservoired in the 4th member of the Middle Triassic Leikoupo Formation are oil-type gases and are believed to be derived from the secondary cracking of oil which is most likely to be generated from the Upper Permian source rocks.
ZHU Dongya , ZHANG Dianwei , LIU Quanyou , JIN Zhijun , HE Zhiliang
2017, 91(6):2214-2229.
Abstract:Well-developed dissolution pores occur in the dolomites of the Sinian Dengying Formation, which is an important oil and gas reservoir layer in the Sichuan Basin and adjacent areas in southern China. The pores are often filled with quartz, and some dolomites have been metasomatically altered to siliceous chert. Few studies have documented the characteristics, source or origin of silica-rich fluids and their effects on the dolomite reservoir. The peak homogenisation temperatures (Th) of fluid inclusions in pore-filling quartz are between 150°C and 190°C, with an average of 173.7°C. Gases in the inclusions are mainly composed of CO2, CH4 and N2. Compared with host dolomite, pore-filling quartz and metasomatic chert contain higher amounts of Cr, Co, Mo, W and Fe, with average concentrations of 461.58, 3.99, 5.05, 31.43 and 6666.83 ppm in quartz and 308.98, 0.99, 1.04, 13.81 and 4703.50 ppm in chert, respectively. Strontium levels are lower than that in the host dolomite, with average concentrations in quartz and chert of 4.81 and 11.06 ppm, respectively. Rare earth element compositions in quartz and chert display positive Eu anomalies with a maximum δEu of 5.72. The δDSMOW values of hydrogen isotopes in water from quartz inclusions vary from ?85.1‰ to ?53.1‰ with an average of ?64.3‰, whereas the δ18OSMOW values range from 7.2‰ to 8.5‰ with an average of 8.2‰. The average 87Sr/ 86Sr ratios in quartz and chert are 0.711586 and 0.709917, respectively, which are higher than that in the host dolomite. The fluid inclusions, elemental and isotopic compositions demonstrate that the formation of quartz and chert was related to silica-rich hydrothermal fluid and that the fluid was the deep circulation of meteoric water along basement faults. Interactions with silica-rich hydrothermal fluids resulted in densification of dolomite reservoirs in the Dengying Formation through quartz precipitation and siliceous metasomatism. However, it increased the resistance of the host dolomite to compaction, improving the ability to maintain reservoir spaces during deep burial. Evidence for silica-rich hydrothermal activity is common in the Yangtze Platform and Tarim Basin and its influence on deep dolomite reservoirs should be thoroughly considered
YANG Guang , LIU Changli , FAN Jiarui , CHEN Peng
2017, 91(6):2230-2242.
Abstract:This work aims to reconstruct the burial history of various kinds of sandstones penetrated by the well YS201 in the Yaoyingtai region of the Changling Fault Depression, southern Songliao Basin, China. Analyses of fluid inclusions in the reservoir rocks, combined with a review of the regional tectonic evolution, revealed the hydrocarbon accumulation stage and accumulation age of the Early Cretaceous Denglouku group and the first member of the Quantou group reservoir, which are the future exploration focus for deep gas reservoirs in this region. Acoustic time data and sedimentary rates calculated for sediments in the YS201 well yielded thicknesses for the Yingcheng, Nenjiang, and Mingshui groups of 506, 539.18, and 144.85 m, respectively, thereby revealing the burial history of the sediments in the well. Fluid inclusions of the Denglouku group reservoir and the first member of the Quantou group reservoir contain oil inclusions and hydro-carbonaceous salt water inclusions. The main peaks of the homogenization temperature and salinity of these saltwater inclusions in the first member of the Quantou group reservoir are generally 110–120°C and 6wt%–8wt%, respectively, and for the Denglouku group are 130–140°C and 4wt%–6wt%. The data for both reservoirs show only one main peak, indicating that they both have experienced single-stage accumulation. Combining the homogenization temperature of the reservoir fluid inclusions with the burial and thermal history of the sediments in the YS201 well, we infer that the hydrocarbon gas in these two intervals accumulated at 79 Ma (middle Late Cretaceous).
SONG Dangyu , LI Chunhui , SONG Boyi , YANG Cunbei , LI Yunbo
2017, 91(6):2243-2254.
Abstract:As the mercury emitted from coal combustion can lead to serious environmental issues, researchers pay more attention to the content, distribution and occurrence of mercury in coal. In this paper, the content, distribution, and occurrence of mercury in the Permian tectonically deformed coals from Peigou Mine, Xinmi coalfield, Henan Province were investigated. A total of 18 bench samples were taken from No.2-1 coals seam in Peigou Mine, including 15 coal bench samples, two roofs and one floor. The mercury concentration, mineral composition, and main inorganic element content of 18 samples were determined by DMA-80 direct mercury analyzer, XRD, and XRF respectively. The results show that the mercury content ranges from 0.047 ppm to 0.643 ppm, with an average of 0.244 ppm. Though the coal seam has turned into typical tectonically deformed coal by the strong tectonic destruction and plastic deformation, the vertical distribution of mercury has remarkable heterogeneity in coal seam section. By the analysis of correlation between mercury and the main inorganic elements and the mineral composition in coal, we infer that majority of mercury mainly relates to pyrite or kaolinite.
LI Shengli , YU Xinghe , ZHANG Feng , LIANG Xingru , LI Shunli , HUANG Jie , CAO Nanzhu
2017, 91(6):2255-2267.
Abstract:The Baxian depression is a typical half-graben located in the Jizhong sub-basin, north China. Commercial petroleum traps have been discovered in the Jizhong sub-basin. However, the 3rd and 4th members of the Shahejie Formation in this sub-basin have been poorly explored. These two members, belonging to the Lower Paleogene age, are buried deeply in the depression. Favorable petroleum reservoir conditions exist in such deep intervals of the half-graben due to the presence of different types and extent of deltas and turbidity fans in various areas. In fact, three types of turbidite fans are developed in the sag below the transitional belt on the eastern gentle slope. This work summarized three stratigraphic trap belts, i.e., the steep slope, gentle slope, and sag. On the steep slope, structural-stratigraphic traps with small-scale delta fronts and turbidite sandbodies are well developed. On the gentle slope, hydrocarbons generally accumulate in the large-scale delta front, onlapping beds and those sandbodies adjacent to unconformities. In the sag, petroleum trap models are typically characterized by pinched-out turbidite sandbodies. Stratigraphic traps were easily formed in turbidite fans below the eastern transitional belt. The petroleum traps that have already been discovered or predicted in the study area indicate that stratigraphic traps have favorable petroleum exploration potential in deeply buried areas (depth >5000 m) in a half-graben basin or depression.
Rajeev?SARASWAT , Manumalenki?MANASA , Thejasino?SUOKHRIE , Mohammad?Syed?SAALIM , Rajiv?NIGAM
2017, 91(6):2268-2282.
Abstract:A total of 97 surface sediment samples were collected from the continental shelf and slope of the western Bay of Bengal to assess the potential application of Asterorotalia trispinosa as a paleomonsoon proxy. The relative abundance of living as well as total (living and dead) A. trispinosa ranges from being absent to a maximum of ~31%. The highest abundance of A. trispinosa is close to the outfall region of the Ganga-Brahmaputra Rivers and decreases away from the river mouths. Contrary to that, A. trispinosa is rare in front of both the Cauvery and Pennar river outfall regions, in the central part of the western Bay of Bengal. The living A. trispinosa abundance is the lowest in between two major river systems, viz. Ganga-Brahmaputra-Mahanadi and Krishna-Godavari. The relative abundance of both the total and living A. trispinosa is strongly positively correlated with ambient seawater temperature, and negatively correlated with %Corg and salinity. Based on the spatial distribution, we conclude that A. trispinosa is stenohaline in nature, rather than euryhaline, and further that the increased relative abundance of A. trispinosa indicates warmer and only marginally hyposaline environment. Even though the ecological preference of A. trispinosa suggests it as a potential paleomonsoon proxy, the restricted distribution implies limited application.
ZHANG Guowei , LI Sanzhong , GUO Anlin , SUO Yanhui
2017, 91(6):2283-2301.
Abstract:The Indian Ocean and the West Pacific Ocean and their ocean-continent connection zones are the core area of "the Belt and Road". Scientific and in-depth recognition to the natural environment, disaster distribution, resources, energy potential of “the Belt and Road” development, is the cut-in point of the current Earth science community to serve urgent national needs. This paper mainly discusses the following key tectonic problems in the West Pacific and North Indian oceans and their ocean-continent connection zones (OCCZs): 1. modern marine geodynamic problems related to the two oceans. Based on the research and development needs to the two oceans and the ocean-continent transition zones, this item includes the following questions. (1) Plate origin, growth, death and evolution in the two oceans, for example, 1) The initial origin and process of the triangle Pacific Plate including causes and difference of the Galapagos and West Shatsky microplates; 2) spatial and temporal process, present status and trends of the plates within the Paleo- or Present-day Pacific Ocean to the evolution of the East Asian Continental Domain; 3) origin and evolution of the Indian Ocean and assembly and dispersal of supercontinents. (2) Latest research progress and problems of mid-oceanic ridges: 1) the ridge-hot spot interaction and ridge accretion, how to think about the relationship between vertical accretion behavior of thousands years or tens of thousands years and lateral spreading of millions years at 0 Ma mid-oceanic ridges; 2) the difference of formation mechanisms between the back-arc basin extension and the normal mid-oceanic ridge spreading; 3) the differentials between ultra-slow dian Ocean and the rapid Pacific spreading, whether there are active and passive spreading, and a push force in the mid-oceanic ridge; 4) mid-oceanic ridge jumping and termination: causes of the intra-oceanic plate reorganization, termination, and spatial jumps; 5) interaction of mantle plume and mid-oceanic ridge. (3) On the intra-oceanic subduction and tectonics: 1) the origin of intra-oceanic arc and subduction, ridge subduction and slab window on continental margins, transform faults and transform-type continental margin; 2) causes of the large igneous provinces, oceanic plateaus and seamount chains. (4) The oceanic core complex and rheology of oceanic crust in the Indian Ocean. (5) Advances on the driving force within oceanic plates, including mantle convection, negative buoyancy, trench suction and mid-oceanic ridge push, is reviewed and discussed. 2. The ocean-continent connection zones near the two oceans, including: (1) Property of continental margin basement: the crusts of the Okinawa Trough, the Okhotsk Sea, and east of New Zealand are the continental crusts or oceanic crusts, and origin of micro-continent within the oceans; (2) the ocean-continent transition and coupling process, revealing from the comparison of the major events between the West Pacific Ocean seamount chains and the continental margins, mantle exhumation and the ocean-continent transition zones, causes of transform fault within back-arc basin, formation and subduction of transform-type continental margin; (3) strike-slip faulting between the West Pacific Ocean and the East Asian Continent and its temporal and spatial range and scale; (4) connection between deep and surface processes within the two ocean and their connection zones, namely the assembly among the Eurasian, Pacific and India-Australia plates and the related effect from the deep mantle, lithosphere, to crust and surface Earth system, and some related issues within the connection zones of the two oceans under the super-convergent background. 3. On the relationship, especially their present relations and evolutionary trends, between the Paleo- or Present-day Pacific plates and the Tethyan Belt, the Eurasian Plate or the plates within the Indian Ocean. At last, this paper makes a perspective of the related marine geology, ocean-continent connection zone and in-depth geology for the two oceans and one zone.
2017, 91(6):2301-2301.
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2017, 91(6):2309-2309.
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WANG Qi , LIU Yunhuan , QIN Jiachen , ZHANG Hu , ZHANG Ya’nan , SHAO Tiequan , ZHANG Ting , WEI Ronghao , ZHANG Hongze , WANG Feng
2017, 91(6):2310-2311.
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Xing Lida , Chou Chunyong , Martin G. LOCKLEY , Yangchen Dolkar , Chen Xingru , Ma Xinghong , Zhou Wenjun , Xu Hantian
2017, 91(6):2312-2313.
Abstract:
CUI Yuliang , Qu Hongjie , CHEN Yingfu , WANG Sen , MENG Xianfeng , SONG Dianlan , ZHANG Wenyong , WANG Huan
2017, 91(6):2330-2332.
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2017, 91(6):2345-2345.
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2017, 91(6):2349-2361.
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2017, 91(6):2362-2365.
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Chief Editor:HOU Zengqian
Governing Body:China Association for Science and Technology
Organizer:Geological Society of China
start publication :1922
ISSN:ISSN 1000-9515
CN:CN 11-2001/P