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
- Most Read
- Most Cited
- Most Downloaded
2017, 91(5):0-0.
Abstract:
2017, 91(5):0-1.
Abstract:
2017, 91(5):1-1.
Abstract:
JIANG Shan , JI Shu-an , MO Jinyou
2017, 91(5):1523-1529.
Abstract:Chroniosuchians are basal tetrapods owing to Anthracosauromorpha and the oldest species of chroniosuchians have been recorded in the Late Permian of Russia so far. In this study, we present evidence for their existence in the Middle Permian of China, based on well preserved diagnostic vertebrae with associated osteoderms from the Dashankou fanua in northwestern China. The finds clearly show interosteoderm articulation pattern between the adjacent scutes in bystrowianids. The features observed in Yumenerpeton yangi may warrant the close proximity or phyletic succession of the chroniosuchid and bystrowianid types of the osteoderm design.
SONG Bowen , ZHANG Kexin , JI Junliang , HAN Fang , WANG Chaowen , WANG Jiaxuan , AI Keke
2017, 91(5):1530-1541.
Abstract:With a thick sequence of early Eocene to Pleistocene terrestrial records, the Qaidam Basin on the northern Tibetan Plateau provides an important sedimentary archive for understanding the paleoenvironmental evolution of the northeast Tibetan Plateau. In this study, specimens of fossil fish remains are collected from the late Middle Miocene (Serravallian, ~12Ma) of the middle member of the Shang Youshashan Formation, Dahonggou (DHG) section, in the northern Qaidam Basin. Based on a systematic study of these materials, the remains have assigned to Cyprinidae, with typical pharyngeal teeth and dorsal fin spines with serrations on the posterior edge. Our discovery improves understanding of the cyprinid fish distribution characteristics in the Qaidam Basin during the Cenozoic. Co-occurrences of terrestrial brackish ostracod species Cyprideis and long chain alkenonesin the layer indicate that the studied cyprinid fish lived in a generally large brackish to saline water body during the late middle Miocene (Serravallian), when the climate of Qaidam Basin was still not sufficiently dry to form an extreme saline water lake.
GUO Caiqing , YAO Jianxin , ZHANG Jianwei , WU Pengcheng , LI Chengsen
2017, 91(5):1542-1552.
Abstract:Sixteen liverwort specimens collected from the Lower Cretaceous Yixian Formation of Huangbanjigou Village, Liaoning Province, China are studied in this work. The plants are thalloid and preserved in brown arenaceous mudstone as impressions. Based on examinations, the liverworts are assigned to two new genera and five new species: Riccardiothallus palmata sp. nov., Pallaviciniites stricta sp. nov., Pellites latithallus gen. et sp. nov., Conocephalumites hexagonites gen. et sp. nov. and Metzgerites multifidus sp. nov., belonging to five families and five genera. The fossil research indicates that the divergence of families, Aneuraceae and Metzgeriaceae, Pallaviciniaceae and Hymenophytaceae, Pelliaceae and Fossombroniaceae, was in the Lower Cretaceous (125 Ma). The research provides significant additions to the fossil liverwort records in Western Liaoning and offers fossil evidence for studying the classification and evolution of extant liverworts.
Amir BARZEGARI , Manouchehr GHORASHI , Hamid NAZARI , Michel FONTUGNE , Mohammad A. SHOKRI , Mohsen POURKERMANI
2017, 91(5):1553-1572.
Abstract:The Astara Fault System (AFS) is located in the northwest Alborz, east of Talesh Mountain (TM) and west of the South Caspian Basin (SCB). The AFS is one of the basement rock faults in Iran that is heavily involved in seismotectonic activity of the Talesh region, and to which subsidence of the SCB is attributed. There is little information available concerning previous AFS seismic activities and its properties. In order to elucidate the seismic behavior and activities of the AFS, we conducted a research study on paleoseismology of the fault. Based on paleoseismic evidence, two scenarios could be taken into consideration, one of which has three and another has four seismic events with magnitudes Mw in the range of 6.7 to 7.2. Evidence of these seismic events is within sedimentary succession as they have occurred during the past 3 ka (this age is determined based on the deposition rate of the region). Six carbon samples were taken for C14 age determination tests, the results of which clearly demonstrated that the EvIV (scenario A) and EvIII (scenario B) had occurred before 27,444 cal BP, while other events occurred in the time period between 27,444 cal BP and 3 ka ago. If we consider the occurrence of three or four seismic events (based on the two scenarios) to be between 27,444 cal BP and 3 ka ago, the average recurrence interval is 7,119 ± 1,017, but evidence for these events has been removed. If we assume EvI to be the youngest event (in both scenarios), the minimum elapsed time is therefore 3 ka.
Sohaib AHMAD , Asghar ALI , Khaista REHMAN
2017, 91(5):1573-1623.
Abstract:Detailed micro–meso to macroscopic structural analyses reveal two deformation phases in the western limb of the Hazara-Kashmir Syntaxis (HKS). Bulk top to NW shearing transformed initially symmetrical NNE–SSW trending meso to macroscopic folds from asymmetric to overturned ones without changing their trend. Sigmoidal en-echelon tension gashes developed during this deformation, that were oblique to bedding parallel worm burrows and bedding planes themselves. Strain analyses of deformed elliptical ooids using the Rf/f method constrain the internal strain patterns of the NNE–SSW structures. The principal stretching axis (S3) defined by deformed elliptical ooids is oriented N27°E at right angles to WNW–ESE shortening. The deformed elliptical ooids in sub-vertical bedding vertical planes contain ooids that plunge ~70° SE due to NW-directed tectonic transport. Finite strain ratios are 1.45 (Rxy) parallel to bedding plane and 1.46 (Ryz) for the vertical plane. From these 2D strain values, we derive an oblate strain ellipsoidal in 3D using the Flinn and Hsu/Nadai techniques. Strains calculated from deformed elliptical ooids average –18.10% parallel to bedding and –18.47% in the vertical plane. However, a balanced cross-section through the study area indicates a minimum of ~–28% shortening. Consequently, regional shortening was only partially accommodated by internal deformation.
ZHANG Beihang , ZHANG Jin , WANG Yannan , ZHAO Heng , LI Yanfeng
2017, 91(5):1624-1643.
Abstract:The apatite fission track (AFT) ages and thermal modeling of the Longshoushan and deformation along the northern Hexi Corridor on the northern side of the Qinghai-Tibetan Plateau show that the Longshoushan along the northern corridor had experienced important multi-stage exhumations during the Late Mesozoic and Cenozoic. The AFT ages of 7 samples range from 31.9 Ma to 111.8 Ma. Thermal modeling of the AFT ages of the samples shows that the Longshoushan experienced significant exhumation during the Late Cretaceous to the Early Cenozoic (~130–25 Ma). The Late Cretaceous exhumation of the Longshoushan may have resulted from the continuous compression between the Lhasa and Qiangtang blocks and the flat slab subduction of the Neo-Tethys oceanic plate, which affected wide regions across the Qinghai-Tibetan Plateau. During the Early Cenozoic, the Longshoushan still experienced exhumation, but this process was caused by the Indian-Eurasian collision. Since this time, the Longshoushan was in a stable stage for approximately 20 Ma and experienced erosion. Since ~5 Ma, obvious tectonic deformation occurred along the entire northern Hexi Corridor, which has also been reported from the peripheral regions of the Qinghai-Tibetan Plateau, especially in the Qilianshan and northeastern margin of the plateau. The AFT ages and the Late Cenozoic deformation of the northern Hexi Corridor all indicate that the present northern boundary of the Qinghai-Tibetan Plateau is situated along the northern Hexi Corridor.
HAN Zhiyong , LI Xusheng , WANG Nairui , CHEN Gang , WANG Xianyan , LU Huayu
2017, 91(5):1644-1652.
Abstract:The stream power model was applied to Lushan Mt. in South China in order to verify its capability of interpreting the uplift of a small block mountain. On a log-log plot, the longitudinal profiles of 9 rivers derived from a 30m DEM exhibit primary characteristics similar to those derived from a 5m DEM; however, the 5m DEM clearly reveals more minor knickpoints, and the positions of knickpoints are pinpointed more accurately. All of the studied rivers on the block mountain are in a transient state due to geological perturbations. Some of them exhibit two segments in steady state separated by a slope-break knickpoint. Such rivers generally develop in a longitudinal valley, which are less perturbed by substrate inhomogeneities. The similar heights of the slope-break knickpoints and the similar uplift rate indicated by the ksn values demonstrate an almost simultaneous headward erosion induced by the fall in base level. This modelling result is consistent with the mode of formation of this particular block mountain. Our study demonstrates that the stream power model is applicable to a small tectonically-active massif only if the channel segments are in a steady state.
2017, 91(5):1653-1679.
Abstract:The Mazaertag layered intrusion is located in the northwestern part of the Tarim large igneous province where several early Permian layered ma?c-ultrama?c intrusions host important Fe-Ti oxide deposits. The intrusion covers an area of ~0.13 km2 and has a vertical stratigraphic thickness of at least 300 m. It consists chie?y of olivine clinopyroxenite, and is cut through by the nearby mafic-ultramafic dykes. In this paper, we report new mineral chemistry data and whole-rock chemical and isotopic compositions for the Mazaertag intrusion along with whole-rock isotopic compositions for the nearby mafic dykes. The averaged compositions of cumulus olivine, clinopyroxene and intercumulus plagioclase within individual samples range from Fo71?73, Mg# = 76 to 79 and An65?75 but they do not define sustained reversals. The observed mineral compositions are consistent with the differentiation of a single batch of magma in a closed system. Rocks of the Mazaertag intrusion are characterized by enrichment in light REE relative to heavy REE, positive Nb and Ta anomalies and a small range of age-corrected εNd(t) (?0.1 to +0.9) and initial 87Sr/86Sr values (0.7044 to 0.7068). The slightly lower εNd(t), initial 206Pb/204Pb and higher initial 87Sr/86Sr values of the intrusion compared to those of the least contaminated dykes [εNd(t) = +2.8 to +3.4; (206Pb/204Pb)i = 18.516?18.521; (87Sr/86Sr)i = 0.7038?0.7041] imply that the Mazaertag magma was subjected to small to modest degrees of contamination by the upper crust. The Sr-Nd isotopic compositions of the least contaminated dykes are consistent with derivation from a FOZO-like mantle source. The parental magma of the Mazaertag intrusion, estimated from clinopyroxene compositions using mineral-melt partition coef?cients, has trace element compositions similar to some of the most primitive mafic dykes in the same area. This suggests that the Mazaertag intrusion and mafic dykes shared a similar mantle source. Therefore, the parental magma of the Mazaertag intrusion was interpreted to have originated from a mantle plume. Based on the Cr2O3 contents in titanomagnetite and less-evolved characteristics of the Mazaertag intrusion compared to the Wajilitag Fe-Ti oxide deposit in Bachu, it is speculated that there might not be a potential to ?nd economic Fe-Ti oxide mineralization in the intrusion.
ZHAO Xiaochen , LIU Chiyang , WANG Jianqiang , DUAN Liang , ZHAO Yan , ZHANG Qihang , LUO Wei
2017, 91(5):1680-1703.
Abstract:The eastern Hexi Corridor Belt (HCB) is located in the transitional belt among the Alxa Block, the Qilian Orogenic Belt and the North China Block. Because of its unique tectonic location, the tectonic setting, provenance, and even the age of the sedimentary strata in the eastern HCB during the Early Paleozoic remain controversial. This study analyzes the provenance of the poorly studied Xiangshan Group, discusses its age of development and tectonic setting in the eastern HCB using a combination of petrological, geochemical and LA-ICP-MS U-Pb zircon dating methods. Based on the youngest age peaks and the fossil evidence, we suggest that the Xiangshan Group is Middle Cambrian to Late Ordovician in age. The complexity of the geochemical characteristics and associated diagrams suggests that the early stage of the Xiangshan Group developed in a passive continental margin environment, late in the back-arc basin of the eastern HCB. Based on the sandstone detrital composition, whole-rock geochemistry and detrital zircon ages, we conclude that the Xiangshan Group had an early provenance that was mainly from the Qilian Block and a late provenance from the Qilian Block and the western Alxa Block. The eastern HCB and its northern and southern blocks have similar palaeontology, lithology and basement age characteristics to the South China Block. This indicates that the eastern HCB might not have formed in the intra-continental aulacogen of the North China Block during the Early Paleozoic but has a close affinity to eastern Gondwana.
YAO Meijuan , CAO Ye , LIU Jiajun , REN Zongbao
2017, 91(5):1704-1716.
Abstract:It is of great importance to understand the origin of UG2 chromitite reefs and reasons why some chromitite reefs contain relatively high contents of platinum group elements (PGEs: Os, Ir, Ru, Rh, Pt, Pd) or highly siderophile elements (HSEs: Au, Re, PGE). This paper documents sulphide-silicate assemblages enclosed in chromite grains from the UG2 chromitite. These are formed as a result of crystallisation of sulphide and silicate melts that are trapped during chromite crystallisation. The inclusions display negative crystal shapes ranging from several micrometres to 100 μm in size. Interstitial sulphide assemblages lack pyrrhotite and consist of chalcopyrite, pentlandite and some pyrite. The electron microprobe data of these sulphides show that the pentlandite grains present in some of the sulphide inclusions have a significantly higher iron (Fe) and lower nickel (Ni) content than the pentlandite in the rock matrix. Pyrite and chalcopyrite show no difference. The contrast in composition between inter-cumulus plagioclase (An68) and plagioclase enclosed in chromite (An13), as well as the presence of quartz, is consistent with the existence of a felsic melt at the time of chromite saturation. Detailed studies of HSE distribution in the sulphides and chromite were conducted by LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry), which showed the following. (I) Chromite contained no detectable HSE in solid solution. (II) HSE distribution in sulphide assemblages interstitial to chromite was variable. In general, Pd, Rh, Ru and Ir occurred dominantly in pentlandite, whereas Os, Pt and Au were detected only in matrix sulphide grains and were clearly associated with Bi and Te. (III) In the sulphide inclusions, (a) pyrrhotite did not contain any significant amount of HSE, (b) chalcopyrite contained only some Rh compared to the other sulphides, (c) pentlandite was the main host for Pd, (d) pyrite contained most of the Ru, Os, Ir and Re, (e) Pt and Rh were closely associated with Bi forming a continuous rim between pyrite and pentlandite and (f) no Au was detected. These results show that the use of ArF excimer laser to produce high-resolution trace element maps provides information that cannot be obtained by conventional (spot) LA-ICP-MS analysis or trace element maps that use relatively large beam diameters.
TANG Huafeng , KONG Tan , WU Chengzhi , WANG Pujun , PENG Xu , GAO Youfeng
2017, 91(5):1717-1732.
Abstract:The Cenozoic volcanostratigraphy in the Changbaishan area had complex building processes. Twenty-two eruption periods have been determined from the Wangtian’e, Touxi, and Changbaishan volcanoes. The complex volcanostratigraphy of the Changbaishan area can be divided into four types of filling patterns from bottom to top. They are lava flows filling in valleys (LFFV), lava flows filling in platform (LFFP), lava flows formed the cone (LFFC), and pyroclastic Flow filling in crater or valleys (PFFC/V). LFFV has been divided into four layers and terminates as a lateral overlap. The topography of LFFV, which is controlled by the landform, is lens shaped with a wide flat top and narrow bottom. LFFP has been divided into three layers and terminates as a lateral downlap. The topography of LFFP is sheet and tabular shaped with a narrow top and wide bottom. It has large width to thickness ratio. It was built by multiple eruptive centers distributed along the fissure. The topography of LFFC, which is located above the LFFP, has a hummocky shape with a narrow sloping top and a wide flat bottom. It terminates as a later downlap or backstepping. It has large width to thickness ratio. It was built by a single eruptive center. The topography of PFFC/V, which located above the LFFC, LFFP, or valley, has the shape of fan and terminates as a lateral downlap or overlap. It has a small width to thickness ratio and was built by a single eruptive center. The filling pattern is controlled by temperature, SiO2 content, volatile content, magma volume, and the paleolandform. In the short term, the eruptive production of the Changbaishan area is comenditic ash or pumice of a Plinian type eruption. The eruptive volume in future should be smaller than that of the Baguamiao?period, and the filling pattern should be PFFC/V, which may cause huge damage to adjacent areas.
ZHANG Guobin , YANG Yanchen , Alexander S. VAKH , Vadim G. KHOMICH , WANG Keyong , YE Songqing , HAN Shijiong
2017, 91(5):1733-1750.
Abstract:The Berezitovoe deposit is a large-sized Au–Ag–Zn–Pb deposit in the east of the Selenga–Stanovoi superterrane, Russia. Au–Ag orebodies are hosted by tourmaline-garnet-quartz-muscovite metasomatic rocks; Zn–Pb orebodies are hosted by granodiorites, porphyritic granites and tourmaline-garnet-quartz-muscovite metasomatic rocks. These orebodies are surrounded by wall rocks dominated by the Tukuringra Complex granodiorites, porphyritic granites, and gneissic granodiorites. The alteration includes silicification and garnet, sericitization chloritization, carbonatization and kaollinization. LA–ICP–MS U–Pb zircon dating indicates that the gold mineralization can be divided into two stages in the Berezitovoe polymetallic gold deposit (at 363.5 ± 1.5 Ma, and133.4 ± 0.5). Hornblende–plagioclase gneisses of the Mogocha Group in the study area underwent Paleoproterozoic metamorphism (at 1870 ± 7.8 and 2400 ± 13 Ma), gneissic granodiorite of the Tukuringra Complex yields a late Paleozoic magmatic age (at 379.2 ± 1.1 Ma), and subalkaline porphyritic granitoid of the Amudzhikan Complex yield late Mesozoic magmatic ages (133–139 and 150–163 Ma). Granodiorites of the Tukuringra Complex in the study area have high concentrations of SiO2 (average of 60.9 wt%), are aluminum-oversaturated (average A/CNK of 1.49), are enriched in the large ion lithophile elements (e.g., K, Rb, and Ba), U, Th, and Pb, are depleted in high field strength elements (e.g., Ta, Nb, and Ti), and have slightly negative Eu and no Ce anomalies in chondrite-normalized rare earth element diagrams. Fluid inclusions from quartz veins include three types: aqueous two-phase, CO2-bearing three-phase, and pure CO2. Aqueous two-phase inclusions homogenize at 167°C–249°C and have salinities of 4.32%–9.47% NaCl equivalent, densities of 0.86–0.95 g/cm3, and formed at depths of 0.52–0.94 km. In comparison, the CO2-bearing three-phase inclusions have homogenization temperatures of 265°C–346°C, salinities of 7.14%–11.57% NaCl equivalent, and total densities of 0.62–0.67 g/cm3. The geochemical and zircon U–Pb data and the regional tectonic evolution of the study area, show that the Berezitovoe polymetallic gold deposit formed in an island arc or active continental margin setting, most probably related to late Paleozoic subduction of Okhotsk Ocean crust beneath the Siberian Plate.
GUAN Yao , SUN Xiaoming , SHI Guiyong , JIANG Xiaodong , LU Hongfeng
2017, 91(5):1751-1766.
Abstract:The rare earth elements (REE) composition of the polymetallic crusts and nodules obtained from the South China Sea (SCS) were analyzed through inductively coupled plasma mass spectrometry. Results revealed great differences in the REE abundances (ΣREE) of the SCS polymetallic crusts and nodules; the crusts show the highest ΣREE, whereas the nodules exhibit the lowest ΣREE. The similarity in their NASC–normalized patterns, the enriched light REE (LREE), the markedly positive Ce anomaly (δCe), and the non– or weakly positive Eu anomaly (δEu), suggest that the polymetallic crusts and nodules are of hydrogenetic origin. Moreover, the REE contents and their relevant parameters are quite different among the various layers of the crusts and nodules, which probably results from the different marginal sea environments and mineral assemblages of the samples. The growth profiles of the SCS polymetallic crusts and nodules reveal the tendency ΣREE and δCe to slightly increase from the outer to the inner layers, suggesting that the growth environments of these samples changed smoothly from an oxidizing to a relatively reducing environment; in addition, the crust ST1 may have experienced a regressive event (sea–level change) during its growth, although the REE composition of the seawater remained relatively stable. On the basis of the regional ΣREE distribution in the SCS crusts and nodules, the samples collected near the northern margin were influenced by terrigenous material more strongly compared with the other samples, and the REE contents are relatively low. Therefore, the special geotectonic environment is a significant factor influencing the abundance of elements, including REE and other trace elements. Compared with the oceanic seamount crusts and deep–sea nodules from other oceans, the SCS polymetallic crusts and nodules exhibit special REE compositions and shale–normalized patterns, implying that the samples are of marginal sea–type Fe–Mn sedimentary deposits, which are strongly affected by the epicontinental environment, and that they grew in a more oxidative seawater environment. This analysis indicates that the oxidized seawater environment and the special nano property of their Fe–Mn minerals enrich the REE adsorption.
GONG Hujun , ZHU Laimin , LI Ben , XIONG Xiao , DING Lele
2017, 91(5):1767-1777.
Abstract:The Tongyu copper deposit, located in the western part of the North Qinling Orogen, China, is one of several volcanic-hosted massive sulphide (VHMS) deposits with industrial value and is also a typical example of mineralization related to the subduction and metallogenesis during the Caledonian orogeny. We conducted systematic lead–sulphur isotope geochemical analyses of the Tongyu deposit to understand the possible ore-forming material sources and tectonic settings. Twenty-six sulphide samples yielded clustered δ34SCDT values of 1.13‰–3.36‰, average 2.22‰, and show a tower-type distribution, implying that the sulphur of the Tongyu copper deposit mainly originated from a mantle source. The Pb isotope compositions of sulphides (206Pb/204Pb = 17.59225–18.56354, average 18.32020; 207Pb/204Pb = 15.51770–15.69381, average 15.66217; 208Pb/204Pb = 37.99969–39.06953, average 38.52722) are close to the values of the volcanic host rocks (206Pb/204Pb = 18.10678–18.26293, average 18.21158; 207Pb/204Pb = 15.63196–15.68188, average 15.65345; 208Pb/204Pb = 38.43676–38.56360, average 38.49171), thus consistent with the Pb in ores and volcanic host rocks having been derived from a common source that was island-arc Pb related to oceanic crust subduction. The northward subduction of the Palaeo–Qinling oceanic crust triggered dehydration of the slab, which generated a large amount of high-oxygen-fugacity aqueous hydrothermal fluid. The fluid rose into the mantle wedge, activated and extracted metallogenic material and promoted partial melting of the mantle wedge. The magma and ore-forming fluid welled up and precipitated, finally forming the Tongyu VHMS copper deposit.
Hammad Tariq JANJUHAH , José Antonio GáMEZ VINTANED , Ahmed Mohamed Ahmed SALIM , Ibrahima FAYE , Mumtaz Muhammad SHAH , Deva Prasad GHOSH
2017, 91(5):1778-1796.
Abstract:The Luconia Province – offshore Sarawak – is a key geological unit for understanding the distribution of hydrocarbon resources in Malaysia. Nevertheless, little effort has been made to address the palaeoenvironmental characteristics of the Tertiary carbonates in the key sector of Central Luconia. We study the sedimentology and petrography of core samples from a well in Central Luconia, for which thirteen microfacies have been identified reflecting different depositional settings. This is the first microfacies scheme elaborated for Luconian carbonates. Lithofacies and microfacies distribution are compatible with deposition in a reef complex, originating around a framework reef, within the euphotic zone. Sediments were deposited in environments of backreef, reef crest, and forereef. The fair weather wave base is marked by the presence of coralline red algae, foraminifera, decreasing degree of bioclast fragmentation and other microfacies features. As a result, a depositional-environmental model is constructed, depicting a reef complex built around a framework reef developed on the margin of an isolated platform. In addition, an innovative, preliminary time series analysis of facies, microfacies and depositional environment data reveal the existence of seasonal cycles in the stacking patterns of facies and microfacies.
Mahnaz SABBAGH BAJESTANI , Asadollah MAHBOUBI , Reza MOUSSAVI-HARAMI , Ihsan AL-AASM , Mehdi NADJAFI
2017, 91(5):1797-1819.
Abstract:The study area is located in the east Tabas Block in Central Iran. Facies analysis of the Qal’eh Dokhtar Formation (middle Callovian to late Oxfordian) was carried out on two stratigraphic sections and applied to depositional environment and sequence stratigraphy interpretation. This formation conformably overlies and underlies the marly-silty Baghamshah and the calcareous Esfandiar formations, respectively. Lateral and vertical facies changes documents low- to high energy environments, including tidal-flat, beach to intertidal, lagoon, barrier, and open-marine. According to these facies associations and absence of resedimentation deposits a depositional model of a mixed carbonate–siliciclastic ramp was proposed for the Qal’eh Dokhtar Formation. Seven third-order depositional sequences were identified in each two measured stratigraphic sections. Transgressive systems tracts (TSTs) show deepening upward trends, i.e. shallow water beach to intertidal and lagoonal facies, while highstand systems tracts (HST) show shallowing upward trends in which deep water facies are overlain by shallow water facies. All sequence boundaries (except at the base of the stratigraphic column) are of the no erosional (SB2) types. We conclude eustatic rather than tectonic factors played a dominant role in controlling carbonate depositional environments in the study area.
YANG Zhi , LI Qiyan , WU Songtao , LIN Senhu , LIU Xinshen
2017, 91(5):1820-1835.
Abstract:The tight sandstone gas in Upper Paleozoic Formation of the northern Ordos Basin is a typical giant unconventional tight gas province. Evidences from geochemistry, reservoir geology and paleo-tectonic setting all verify that the present-day tight sandstone gas accumulation in the Ordos Basin is the result of near-source accumulation. The evidences are listed as following: tight sandstone gas is mainly distributed in the area with high gas-generating strength; gas composition was not subjected to fractionation; gas saturation significantly decreases with the distance away from the source rocks; gas isotopes suggest their origin is the same and maturity is consistent with in-place source rocks; reservoirs have experienced three types of densification digenesis, including intense compaction, siliceous cementation and calcareous cementation, which took place before the formation of a large amount of tight sandstone gas, forming tight reservoirs with low porosity and permeability, fine pore throat and great capillary resistance; the paleo-structural gradient ratio is small from the main hydrocarbon generation period to present. It is indicated the present distribution of tight sandstone gas in the northern Ordos Basin is the result of near-source and short-distance migration and accumulation.
XIE Zengye , LI Jian , LI Zhisheng , GUO Jianying , LI Jin , ZHANG Lu , DONG Caiyuan
2017, 91(5):1836-1854.
Abstract:The alternative development of coal-bearing hydrocarbon source rocks and low-porosity and low-permeability tight sandstone reservoirs of the Triassic Xujiahe Formation in the Sichuan Basin is favorable for near-source hydrocarbon accumulation. The natural gas composition of the Xujiahe Formation in the Sichuan Basin is dominated by hydrocarbon gases, of which the methane content is 80.16%–98.67%. Typically, the C2+ content is larger than 5% in main wet gas. The dry gas is mainly distributed in the western and northern regions of the basin. The non-hydrocarbon gases mainly contain nitrogen, carbon dioxide, hydrogen, and helium, with a total content of <2%. The carbon isotope ranges of methane and its homologues in natural gas are: δ13C1 of ?43.8‰ to ?29.6‰, δ13C2 of ?35.4‰ to ?21.5‰, δ13C3 of ?27.6‰ to ?19.8‰, and δ13C4 of ?27.7‰ to ?18.8‰. δ13C3>δ13C4 occurs in some natural gas with a low evolution degree; such gas is mainly coal-related gas from humic-type source rocks of the Xujiahe Formation. As for the natural gas, δ2HCH4 values ranged from ?195‰ to ?161‰, δ2HC2H6 values ranged from ?154‰ to ?120‰, and δ2HC3H8 values ranged from ?151‰ to ?108‰. The dry coefficient, δ13C and δ2HCH4 are all positively correlated with the maturity of source rocks. The higher the maturity of source rocks is, the larger the natural gas dry coefficient is and the larger the δ13C and δ2HCH4 values are, indicative of the characteristic of near-source accumulation. The δ2HC2H6 value of natural gas is influenced by paleosalinity to a relatively large extent; the higher the paleosalinity is, the larger the δ2HC2H6 value is. The Pr/Ph value of the condensate oil ranged from 1.60 to 3.43, illustrating light oxidization–light reduction and partial-oxidization characteristics of the depositional environment of coal-bearing source rocks of the Xujiahe Formation. The natural gas light hydrocarbon (C5–C7) from the Xujiahe Formation presented two characteristics: the first was the relatively high aromatic hydrocarbon content (19%–32.1%), which reveals the characteristic of natural gas with humic substances of high-maturity; the second was the low content of aromatic hydrocarbon (0.4%–9.3%), reflecting water-washing during the accumulation of the natural gas. The reported research outcomes indicate a potential mechanism for natural gas accumulation in the Xujiahe Formation, which will further guide natural gas exploration in this region.
JIANG Youlu , LIU Hua , SONG Guoqi , WANG Yongshi , LIU Jingdong , ZHAO Kai , LYU Xueying
2017, 91(5):1855-1872.
Abstract:Significant differential hydrocarbon enrichment occurs in depressions in a petroliferous basin. There are multiple depressions in the Bohai Bay Basin, and each depression as a relatively independent unit of hydrocarbon generation, migration and accumulation, contains significantly different hydrocarbon generation conditions and enrichment degree. On the basis of previous documents and a large number of statistical data, this work comparatively analyzed the differential hydrocarbon enrichment and its major controlling factors in depressions of the Bohai Bay Basin. The results show that depressions in the Bohai Bay Basin have various hydrocarbon enrichment degrees, and can be categorized into four types, namely enormously oil-rich, oil-rich, oily and oil-poor depressions. In general, the enormously oil-rich and oil-rich depressions are distributed in the eastern part of the basin along the Tan–Lu and Lan–Liao faults, whereas depressions in the western part of the basin are poor in hydrocarbons. Moreover, the vertical distribution of hydrocarbons is also highly heterogeneous, with Pre-Paleogene strata rich in hydrocarbons in the northern and western depressions, Paleogene strata rich in hydrocarbons in the entire basin, and Neogene strata rich in hydrocarbons in the off-shore areas of the Bohai Bay Basin. From early depressions in onshore areas to the late depressions in offshore areas of the Bohai Bay Basin, the source rocks and source-reservoir-cap rock assemblages gradually become younger and shallower, and the hydrocarbon resource abundance gradually increases. Hydrocarbon supplying condition is the key factor constraining the hydrocarbon enrichment for different depressions, while the main source-reservoir-cap rock assemblage, sufficient hydrocarbons and the transportation capacity of faults control the vertical distribution of hydrocarbons. The main factors controlling hydrocarbon enrichment are different for different layers. The hydrocarbon supplying condition of source rocks is the key controlling factor, whereas the source-reservoir configuration, the main source-reservoir-cap rock assemblages, and the fault transportation are the main factors of hydrocarbon enrichment in the Paleogene, Paleogene and Neogene, respectively.
LIU Wei , HE Siming , OUYANG Chaojun
2017, 91(5):1873-1883.
Abstract:To investigate the movement?mechanism?of debris flow,?a two-dimensional, two-phase, depth-integrated model is introduced. The model uses Mohr-Coulomb plasticity for the solid rheology, and the fluid stress is modeled as a Newtonian fluid. The interaction between solid and liquid phases, which plays a major role in debris flow movement, is assumed to consist of drag and buoyancy forces. The applicability of drag force formulas is discussed. Considering the complex interaction between debris flow and the bed surface, a combined friction boundary condition is imposed on the bottom, and this is also discussed. To solve the complex model equations, a numerical method with second-order accuracy based on the finite volume method is proposed. Several numerical experiments are performed to verify the feasibilities?of model and numerical schemes. Numerical results demonstrate that different solid volume fractions substantially affect debris flow movement.
WANG Ning , LI Suting , HU Yaowu , SONG Guoding
2017, 91(5):1884-1892.
Abstract:We present here a pilot study to examine trophic level effects and migration patterns at the middle Shang Dynasty site of Xiaoshuangqiao in Henan Province using δD results combined with δ13C and δ15N values. A total of 33 specimens (17 humans, 7 cattle, 5 pigs, 3 sheep, 1 dog) of bone collagen were isotopically analyzed for δ13C, δ15N, and dD values. A strong positive correlation (R2 = 0.94) between mean δ15N and δD values of herbivores (cattle and sheep), omnivores (pig), carnivores (dog) and humans was observed. The δD results were found to increase by ~10‰ to 20‰ from herbivores to omnivores to carnivorous, evidence that collagen δD results are a useful indicator for the study of trophic levels and dietary patterns at archaeological sites. The δD results were also used to examine the origins of two different groups of individuals buried at Xiaoshuangqiao. Individuals buried in sacrificial pits of district V had mean δD values (?47.0 ± 2.9‰, n = 11) that were significantly (p = 0.049) elevated compared to the people buried in the stratigraphy of district IX (?51.3 ± 3.3‰, n = 3), indicating that they were ingesting water from different locations. In addition, the D values of the people buried in the stratigraphy were similar to the pigs (?54.5 ± 4.2‰, n = 5) at Xiaoshuangqiao, suggesting that they were most probably of the local population, and that the individuals buried in the sacrificial pits were most possibly from the coast and prisoners of the Dongyi (“东夷”) people. Thus, δD results have the potential to examine human origins and migration patterns and should be increasingly used in conjunction with δ13C and δ15N values at archaeological sites.
2017, 91(5):1892-1893.
Abstract:
SHAO Tiequan , ZHANG Hu , WANG Qi , LIU Yunhuan , ZHANG Yanan
2017, 91(5):1893-1903.
Abstract:The Jehol fauna was initially represented by a bony fish, concostracan and an insect, as a Lycoptera davidi–Eosestheria–Ephemeropsis trisetalis association, but since the researches of recent decades, the Jehol Biota is now completely different from the past low-diversity, and encompasses a native terrestrial biota that includes many well-preserved vertebrates, invertebrates and plants. There are more than 20 important biological categories, thousands of taphonomically unusual fossils, especially noted for the wide variety of biological tissues. The Jehol Biota has caused a sensation in the world with its wide distribution, large quantity, great variety, fine preservation and detailed information, which records the rise and fall of the numerous taxa, and provides significant evidence for three origins: of birds, eutherian mammals, and angiosperms. The Jehol Biota is a highlight of basic scientific research in China, and we honor it as a world–class fossil treasury and “a Mesozoic Pompeii”.
2017, 91(5):1903-1094.
Abstract:
2017, 91(5):1905-1906.
Abstract:
DU Qingxiang , HAN Zuozhen , SHEN Xiaoli , HAN Chao , SONG Zhigang , GAO Lihua , HAN Mei , ZHONG Wenjian , YAN Junlei
2017, 91(5):1910-1914.
Abstract:
WANG Chaoyang , MENG En , LI Yanguang , CAI Jia , YANG Hong , LI Zhuang
2017, 91(5):1919-1923.
Abstract:
WANG Chenglong , ZHANG Meisheng , SUN Kai , WANG Yini , LI Xiaobo , LIU Xuesong
2017, 91(5):1924-1925.
Abstract:
LU Shansong , QIU Xiaofei , JIANG Tuo , PENG Lianhong , ZHAO Xiaoming , WEI Yunxu , DUAN Ruichun , WU Nianwen
2017, 91(5):1926-1927.
Abstract:
2017, 91(5):1936-1937.
Abstract:
SONG Yougui , LI Yue , LI Yun , AN Zhisheng , CHENG Liangqing , SUN Huanyu , Rustam OROZBAEV
2017, 91(5):1942-1943.
Abstract:
2017, 91(5):1943-1944.
Abstract:
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