典型文献
Organic geochemistry characteristics of Jurassic black shales from the Amdo area,northern Tibet,China
文献摘要：
The Jurassic black shales of the Qiangtang Basin,northern Tibet are known to be amongst the most important source rocks.To date,there is no detailed study on the organic geochemistry of the Bathonian/Calllovian coccolith-bearing sediments and their source-rock charac-teristics.Here,we focus on the black limestones,marls,and shales at the Amdo 114 station section using Rock-Eval pyrolysis and biomarkers for sources,types,and thermal maturity of organic matter and the reconstructed depositional environment.All samples are characterized by(1)relatively high TOC values(0.20-2.56 wt％)and rela-tively low Tmax values between 428 and 452℃;(2)short-chain n-alkanes with a maximum at C14 to C18 and Pr/Ph＞1;(3)31-35 homohopanes and gammacerane with lower abundance;and(4)C27-C28-C29 regular steranes with C29 being slightly dominant.The organic matter is Type Ⅱ and thus dominantly derived from phytoplankton,especially algae.Thermal maturity indicators include the Ts/(Ts+Tm),C31 22S/(22S+2R),C29 ααα20S/(20S+0R),C29 ββ/(ββ+αα)and C27 Dia/(Dia+Reg),which are regarded as immature to very early mature.Additionally,the high Pr/Ph,Pr/nC17,and Ph/nC18 ratios,Pr/Ph vs Gammacerane index suggest that these black shales were deposited in unstratified marine waters of normal salinity under dysoxic to weakly reduced conditions.
文献关键词：
中图分类号：
作者姓名：
Guiwen Xu;Lan Chen;Weiguang Zhu;Xuejuan Da;Zhangxiong Zhu;Haisheng Yi
作者机构：
State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,99 West Lincheng Road,Guiyang 550081,China;University of Chinese Academy of Sciences,Beijing 100049,China;Department of Earth Sciences,Chongqing University of Science and Technology,Chongqing 401331,China;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China
文献出处：
引用格式：
[1]Guiwen Xu;Lan Chen;Weiguang Zhu;Xuejuan Da;Zhangxiong Zhu;Haisheng Yi-.Organic geochemistry characteristics of Jurassic black shales from the Amdo area,northern Tibet,China)[J].地球化学学报（英文版）,2022(03):393-405
A类：
Amdo,Bathonian,Calllovian,coccolith,marls,homohopanes,gammacerane,22S+2R,20S+0R,Dia+Reg,Gammacerane,unstratified,dysoxic
B类：
Organic,geochemistry,characteristics,Jurassic,black,shales,from,area,northern,Tibet,China,Qiangtang,Basin,known,amongst,most,important,rocks,To,date,there,detailed,study,organic,bearing,sediments,their,Here,focus,limestones,station,section,using,Rock,Eval,pyrolysis,biomarkers,sources,types,thermal,maturity,matter,reconstructed,depositional,environment,All,samples,characterized,by,relatively,high,TOC,values,wt,Tmax,between,short,chain,alkanes,maximum,C14,Pr,Ph,lower,abundance,C27,C28,C29,regular,steranes,being,slightly,Type,thus,dominantly,derived,phytoplankton,especially,algae,Thermal,indicators,include,Ts+Tm,C31,which,regarded,immature,very,early,Additionally,nC17,nC18,ratios,suggest,that,these,were,deposited,marine,waters,normal,salinity,under,weakly,reduced,conditions
AB值：
0.520098
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