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Early–Middle Cambrian Palynomorph Microfossils and Related Geochemical Events in south china

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Journal of Earth Science 2016年第2期27卷 180-186页

作者： Leiming Yin Chunjiang Wang Yuanlong Zhao Zhiji Ou State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences 39 East Beijing Road Nanjing 210008 China State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum Beijing 102249 China College of Resource and Environment of Guizhou University Guiyang 550003 China

The earliest Cambrian acritarch ＇Asteridium-Heliosphaeridium-Comasphaeridium＇ assemblage and the Early Cambrian（＇Chiungchussuan＇） acritarch ＇Skiagia ornate-Fimbriaglomerella membranacea＇ assemblage in south china.can be correlated with assemblages from synchronous strata elsewhere in the world. Recent geochemical study and biomarker evidence further confirm a biostratigraphic change between Cambrian Series 2 and Series 3 and support the recognition of a major geological and biotic event during this time interval.

关键词： Early-Middle Cambrian acritarchs geochemistry south china.

Preliminary Estimation of Paleoproductivity via TOC and Habitat Types:Which Method Is More Reliable?—A Case Study on the Ordovician-Silurian Transitional Black Shales of the Upper Yangtze Platform, south china

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Journal of china.University of Geosciences 2008年第5期19卷 534-548页

作者：苏文博王永标 Bradley D Cramer Axel Munnecke 李志明傅力浦 School of the Earth Sciences and Resources China University of GeosciencesBeijing 100083 China Key Laboratory of Biogeology and Environmental Geology of Ministry of Education China University of GeosciencesWuhan 430074 China Faculty of Earth Sciences China University of GeosciencesWuhan 430074 China Division of Geological Sciences School of Earth Sciences The Ohio State UniversityColumbus Ohio 43210 USA GeoZentrum Nordbayern Fachgruppe Paloumwelt Universitt ErlangenErlangen D-91054 Germany Xi’an Institute of Geology and Mineral Resources Chinese Academy of Geological SciencesXi’an 710054 China

New total organic carbon （TOC） data from the two Ordovician-Silurian transitional graptolite-bearing black shale intervals, the Wufeng （五峰） Formation and the Longmaxi （龙马溪） Formation in Central Guizhou （贵州） and West Hubei （湖北）, respectively, as well as previously reported TOC data from the same intervals in other places on the Yangtze platform of south china. have been used to produce an initial estimate of the primary paleoproductivity via a conventional inverse method （i.e., ***）. The values of the *** are estimated to be 32 （43-21） gC/（m^2·a）（Wufeng Formation） and 21 （27-16） gC/（m^2·a）（Longmaxi Formation）. Also, simultaneously, the habitat types （i.e., HT; cf., BA： benthic assemblage） and their temporal and spatial changes have been documented from the same succession, and an initial estimate of the primary paleoproductivity has been produced using a forward method （i.e., Rpp-forward） Beingbounded mainly by the peritidal to inner-shelf environment shelly-facies or mixed-facies successions with BA1 to BA3 faunas both at the top and the base, which indicates the habitat types from HT Ⅱ to HT Ⅲ2, the biohabitat type of the two graptolite-bearing black shale intervals can be limited to HT III to HT IV, corresponding to the inner shelf to the outer shelf, with depths from roughly 60 m to 200-300 m. Based on the current data from the south china.Sea and the southern part of the East china.Sea, values of Rpp-forward should be about 100 to 400 gC/（m^2·a）. The difference in the results via the two methods suggests that paleoproductivity estimates from the geological strata need to be made cautiously, with particular attention paid to the paleogeographic setting, oxic-anoxic conditions, as also the preservation factor of organic carbon.

关键词： primary productivity black shale TOC habitat type (HT) Ordovician-Silurian transition south china.

Trace Elements Characteristics of Black Shales from the Ediacaran Doushantuo Formation, Hubei Province, south china. Implications for Redox and Open vs. Restricted Basin Conditions

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Journal of Earth Science 2018年第2期29卷 342-352页

作者： Bi Zhu Shaoyong Jiang Daohui Pi Lu Ge Jinghong Yang Institute of Isotope Hydrology School of Earth Sciences and Engineering Hohai University Nanjing 210098 China State Key Laboratory of Geological Processes and Mineral Resources Faculty of Earth Resources Collaborative Innovation Center for Exploration of Strategic Mineral Resources China University of Geosciences Wuhan 430074 China State Key Laboratory for Mineral Deposits Research School of Earth Sciences and Engineering Nanjing University Nanjing 210093 China

In the present study, we carried out trace element analyses of black shales of the Edia- caran Doushantou Formation from two sections （Jiulongwan, Baiguoyuan） in Hubei Province, south china. Mo-U characteristics of black shales from the two sections and compiled Mo-U data of Dou- shantuo black shales from sections of a variety of sedimentary facies described the temporal/spatial variability in the redox conditions of paleo-seawater during deposition of the Donshantuo Formation. Changes in Mo-U patterns of the Doushantuo Member II （DST2） shales of open marine environments are consistent with a shift from a predominately oxic to a predominately anoxic ocean during their deposition. Mo-U patterns of the DST2 black shales from intra-shelf sections reflect basin restriction may have happened in the intra-shelf basin and are compatible with the redox-stratified model of the intra-shelf basin. Mo-U patterns of black shales of the Doushantuo Member IV （DST4） reveal that the shales from intra-shelf sections have more pronounced Mo enrichment and more significant enrich- ment of Mo over U than the slope shales, indicating the operation of a Mn particulate shuttle in the intra-shelf basin. High Mo/TOC ratios of the DST4 at the intra-shelf sections, in combination with similar Mo-TOC patterns of the DST4 from both intra-shelf and slope sections, indicate the intra- shelf basin was well connected to the open ocean during deposition of the DST4.

关键词： Doushantuo Formation Mo-U eovariation Mo/TOC south china.

Red Palaeosols Development in Response to the Enhanced East Asia Summer Monsoon since the Mid-Pleistocene in south china. Evidence Derived from Magnetic Properties and Molecular Fossil Records

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Journal of Earth Science 2013年第3期24卷 382-396页

作者：顾延生黄咸雨张卫国洪汉烈李永涛 State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences Hubei Key Laboratory of Wetland Evolution & Eco-Restoration (WEER) China University of Geosciences State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Faculty of Earth Sciences China University of Geosciences State Key Laboratory of Estuarine and Coastal Research East China Normal University Faculty of Earth Sciences China University of Geosciences Institute of Geophysics and Geomatics China University of Geosciences

Although Pleistocene red paleosols are widely distributed in south china. paleoenviron-mental interpretation has proved difficult because of intense weathering. Here we combine data from molecular fossil and magnetic properties to reconstruct a record of changes in pedogenic intensity for red paleosols in southeast china. Depth distribution pattern of magnetic properties indicates that lower （higher） χ but higher （lower） values of HIRM （hard isothermal remanent magnetization） and SIRM （saturation isothermal remanent magnetization）/χ has tight relationship with the intensity of pedogenesis,especially the occurrence of well-developed net-like veins, which is absolutely responsible for the presence of anti-ferromagnetic minerals at the cost of fine-grained SP （superparamagnetic）/SD （single domain） ferrimagnetic minerals. The carbon distribution pattern of n-alkanes, n-alkanols, and n-alkanoic acids reflects the predominant contributions of microorganisms to the organic matter during pedogenesis, which provide direct evidence for strong microbial activities in response to theextremely hot-humid condition while white coarse net-like veins occurrence. Our results demonstrate that the presence of the enhanced East Asia summer monsoon has played a key role in the oxide-dominated weathering regime, and pedogenesis, and microbial activities. Changes in molecular ratios and magnetic properties are used to show that red paleosols have undergone three stages of soil formation in striking response to the evolution of the East Asia summer monsoon：（1） the most effective since the Middle Pleistocene; （2） moderately effective since 270 ka or so; （3） least effective since the last glacial. Our research provides important evidence to understand how red paleosols espond to global change since the Middle Pleistocene.

关键词： red paleosols magnetic property molecular fossil pedogenic intensity East Asia sum- mer monsoon south china.

Ages, Trace Elements and Hf-Isotopic Compositions of Zircons from Claystones around the Permian-Triassic Boundary in the Zunyi Section, south china. Implications for Nature and Tectonic Setting of the Volcanism

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Journal of Earth Science 2015年第6期26卷 872-882页

作者： Qiuling Gao Zhong-Qiang Chen Ning Zhang William L.Griffin Wenchen Xia Guoqing Wang Tengfei Jiang Xuefei Xia Suzanne Y.O'Reilly Exploration & Development Research Institute Zhongyuan Oilfield Company School of Earth Sciences China University of Geosciences Australian Research Council Centre of Excellence for Core to Crust Fluid Systems and GEMOC National Key Centre Department of Earth and Planetary Science Macquarie University State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences Shandong Lunan Institute of Geo-Engineering Exploration Jianghan Oilfield Company

A growing body of evidence shows that volcanism near the Permian-Triassic boundary（PTB） may be crucial in triggering the Permian–Triassic（P–Tr） mass extinction. Thus, the ash beds near the PTB in south china.may carry information on this event. Three volcanic ash layers, altered to clay, outcropped in the PTB beds in Zunyi Section, Guizhou Province, southwest china. The U-Pb ages, trace elements, and Hf-isotope compositions of zircon grains from these three ash beds were analyzed using LA-ICPMS and LA-MC-ICPMS. The zircons are mainly magmatic in origin（241-279 Ma） except for two inherited/xenocrystic zircons（939 and 2 325 Ma）. The ages of these magmatic zircons indicate three episodes of magmatism which occurred around the MiddleLate Permian boundary（-261.5 Ma, MLPB）, the Wuchiapingian-Changhsingian boundary（-254.5 Ma, WCB）, and the PTB（-250.5 Ma）, respectively. The first two episodes of magmatism near the MLPB and WCB may be attributed to magmatic inheritance or re-deposition. All magmatic zircons share similar trace-element and Hf-isotope compositions. They have Y, Hf, Th and U contents and Nb/Ta ratios are typical of zircons from silicic calc-alkaline magmas. These zircons also exhibit enriched Hf-isotope compositions with _（εHf）（t） values of-11.4 to ＋0.2, which suggests that the three magmatic episodes involved melting of the continental crust. The more enriched Hf-isotope composition （_（εHf）（t）=-11.4--4.8） of Bed ZY13（-250.5 Ma） implies more input of ancient crustal material in the magma. Integration of the Hf-isotope and trace-element compositions of magmatic zircons suggest that these three episodes of magmatism may take place along the convergent continent margin in or near southwestern south china.as a result of the closure of the Palaeo-Tethys Ocean.

关键词： Permian-Triassic boundary zircon trace elements Hf isotope silicic volcanism,convergent continental margin south china.

Transformation from Neoproterozoic Sinistral to Early Paleozoic Dextral Shearing for the Jingdezhen Ductile Shear Zone in the Jiangnan Orogen, south china

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Journal of Earth Science 2018年第2期29卷 376-390页

作者： Xianbing Xu Shoufa Lin Shuai Tang Xuefen Zhang School of Earth Sciences China University of Geosciences Department of Earth and Environmental Sciences University of Waterloo School of Resources and Environment Hefei University of Technology No.266 Geological Party Nuclear Industry Geological Bureau of Jiangxi Province State Key Laboratory for Nuclear Resources and Environment East China Institute of Technology

The Jingdezhen ductile shear zone is evolved from the Neoproterozoic Zhangyuan ophiolite melange belt in the eastern Jiangnan Orogen, south china. Comprehensive study of geometry, kinematics, quartz c-axis fabric, temperature-pressure conditions and geochronology were conducted in this study. The Jingdezhen shear zone extends -180 km along the NE orientation with two groups of subvertical fo- liation and subhorizontal lineation. One group of foliation strikes NEN orientation whereas another one NEE orientation. Field investigation, microscopic observation and quartz c-axis fabric show that sinistral shearing along NEN-striking foliation occurred earlier than dextral shearing along NEE-striking foliation. Syn-tectonic staurolite porphyroblasts and deformation manner of feldspar imply that sinistral shearing occurred at 530-420 ℃ and 6-2 kbar. Deformation manner and c-axis fabric of quartz and pre-tectonic staurolite porphyroblasts indicate that dextral shearing took place at 420-300 ℃. LA-ICP-MS zircon U-Pb and mica ^40Ar/^39Ar dating indicate that the sinistral shearing occurred during Neoproterozoic oro- geny （830-800 Ma） whereas the dextral shearing at 447＋12 Ma. The sinistral shearing resulted from the Neoproterozoic final assembly between the Yangtze and Cathaysia blocks. The dextral shearing was caused by Early Paleozoic orogen parallel extension and clockwise rotation.

关键词： Jingdezhen ductile shear zone quartz c-axis fabric temperature-pressure condition geochronology Jiangnan Orogen south china.

Timing of Uranium Mineralization and Geological Implications of Shazijiang Granite-Hosted Uranium Deposit in Guangxi, south china. New Constraint from Chemical U-Pb Age

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Journal of Earth Science 2015年第6期26卷 911-919页

作者： Jincheng Luo Ruizhong Hu Shaohua Shi State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry Chinese Academy of Sciences University of Chinese Academy of Sciences Hunan Institute of Geological Survey

Miaoershan（MES） uranium ore field is one of the most important uranium sources in china. hosts the largest Chanziping carbonaceous-siliceous-pelitic rock type uranium deposit in south china.together with many other granite-hosted uranium deposits. The Shazijiang（SZJ） uranium deposit is one of the representative granite-hosted uranium deposits in the MES uranium ore field, situated in the Ziyuan, Guangxi Province, south china. Uranium mineralization in the SZJ deposit mainly occurs as uraninite with quartz and calcite veins that is spatially associated with mafic dykes in the region. The hydrothermal alteration includes silicification, carbonation and hematitization. New uraninite chemical U-Pb geochronology and petrographic evidences provide the timing constraints and new insights into the formation of the SZJ uranium deposit. The results show that the first stage of uranium mineralization formed at 97.5±4.0 Ma, whereas another stage of uranium mineralization occurred at 70.2±1.6 Ma. Two stages of uranium mineralization are fairly consistent with two episodic crustal extensions that occurred at -100 and -70 Ma throughout south china. This study indicates that there are two uranium mineralization events in SZJ uranium ore field controlled by mafic dyke, supporting that mafic dykes play an important topochemical role in uranium concentration and/or mobilization. Therefore, geochemical U-Pb age firstly reinforces that ore-forming age of the SZJ uranium deposit mainly yields at 97.5±4.0 and 70.2±1.6 Ma. Additionally, geochemical age method is particularly useful for interest samples which record information on multi-stage uranium mineralizations in south china.

关键词： Shazijiang uranium deposit uraninite U-Pb age EMPA uranium mineralization crustal extension south china.

The Marine Redox Change and Nitrogen Cycle in the Early Cryogenian Interglacial Time: Evidence from Nitrogen Isotopes and Mo Contents of the Basal Datangpo Formation, Northeastern Guizhou, south china

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Journal of Earth Science 2016年第2期27卷 233-241页

作者： Wei Wei Dan Wang Da Li Hongfei Ling Xi Chen Guangyi Wei Feifei Zhang Xiangkun Zhu Bin Yan State Key Laboratory for Mineral Deposits Research Department of Earth Sciences Nanjing University Institute of Geology CAGS Laboratory of Isotope Geology MLR State Key Laboratory for Continental Tectonics and Dynamics

Cryogenian Datangpo Formation was deposited during the interglacial time between the Sturtian and Marinoan ice ages. We studied nitrogen isotope compositions and contents of Mo of the black shales from the basal Datangpo Formation in northeastern Guizhou, south china. for an attempt to reconstruct the marine redox change and nitrogen cycle during the interglacial time. Based on lithostratigraphy as well as geochemical profiles, the basal black shales can be divided into four intervals： Interval 1 has the lowest δ^（15）N value（＋5.0‰）; in interval 2, δ^（15）N values vary between ＋6.4‰ and ＋7.4‰（the first peak）; interval 3 records stable values of δ^（15）N around ＋6‰; and interval 4 is characterized by its higher δ^（15）N values, between ＋6.7‰ and ＋7.8‰（the second peak）. The values of enrichment factor of Mo decrease from 56.8 to 2.6 with the ascending stratigraphic trend. It indicated that immediately after the Sturtian glaciations, the marine seawater above the transitional zone between the shelf to slope of the southern margin of the Yangtze Platform was stratified, with shallow seawater being oxic but deep water being sulfidic. Subsequently, high denitrification rates prevailed in expanded suboxic areas in spite of a short emergence of an oxic condition in the surface seawater, and the deep seawaters were still anoxic or even euxinic.

关键词： nitrogen isotope molybdenum content Early Cryogenian interglacial time black shale,Datangpo Formation Yangtze Platform south china.

Megascopic Symmetrical Metazoans from the Ediacaran Doushantuo Formation in the Northeastern Guizhou,south china

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Journal of china.University of Geosciences 2008年第3期19卷 200-206页

作者：王约王训练黄禹铭 School of the Earth Sciences and Resources China University of GeosciencesBeijing 100083 China School of Resources and Environments Guizhou University Guiyang 550003 China

In south china. various megascopic symmetrical metazoan fossils were found in the upper Doushantuo （陡山沱） Formation of the Neoproterozoic Ediacaran. The worm-like fossil is characterized by modern taxological annelid, for many metameres, parapodia, one possible tentale, an alimentary canal, and a dorsal vessel. The triradiate discoidal fossils belong to Trilobozoa, and the octaradiate discoidal fossil might be Ctenophora. All these fossils indicate that the megascopic metazoans have appeared in the Doushantuoian of Eidacaran and imply that the symmetrical metazoans must have originated at least 550 Ma ago.

关键词： symmetrical metazoan Doushantuo Formation Neoproterozoic Ediacaran south china.