柴达木盆地中部上油砂山组泥岩地球化学特征及古环境古气候  

Characteristics of geochemistry,paleoenvironment and paleoclimate of mudstone in the Shangyoushashan Formation in the central Qaidam Basin

作　　者：陈晶源 陈金牛 祁善智 汪青川 宋桂春 张明珠 CHEN Jingyuan;CHEN Jinniu;QI Shanzhi;WANG Qingchuan;SONG Guichun;ZHANG Mingzhu(Qaidam Comprehensive Geological and Mineral Exploration Institute of Qinghai Province,Golmud 816099,Qinghai,China;Qing-hai Provincial Key Laboratory of Exploration Research of Salt Lake Resources in Qaidam Basin,Golmud 816099,Qinghai,China)

机构地区：[1]青海省柴达木综合地质矿产勘查院,青海格尔木816099 [2]青海省柴达木盆地盐湖资源勘探研究重点实验室,青海格尔木816099

出　　处：《矿产勘查》2025年第1期67-81,共15页Mineral Exploration

基　　金：国家重点研发计划项目“青海柴北陆相深层砂砾型卤水富钾规律、勘查技术与增储示范”(2023YFC2906501);青海省地质矿产勘查开发局(青地矿水[2023]5号)联合资助。

摘　　要：泥岩不仅记录了地球的沉积历史,还为理解古环境演化和气候变化提供了重要信息。本文以柴达木盆地中部鸭湖地区Y43钻孔上油砂山组泥岩为研究对象,对该钻孔22个样品(5.289~5.246 Ma)进行微量元素和稀土元素分析。研究表明,研究区具有明显的Eu负异常,指示沉积物继承了长英质地壳的风化产物。古盐度指标Sr/Ba、Th/U指示陆相淡水环境,古氧化还原指标V/Cr、Ni/Co、U/Th、V/Sc一致指示为氧化环境,古气候指标Sr/Cu值与Sr、Rb/Sr值反映了整体偏湿的气候环境,并伴随波动性干旱气候特征。结合沉积综合柱状图和构造演化历史,本文认为自9.7 Ma以来,青藏高原隆升及特提斯海退导致了阶段性干旱气候,但研究区上油砂山组沉积早期仍是以偏湿润气候为主。Mudstones not only record the sedimentary history of the Earth,but also provide important informa⁃tion of the evolution of paleoenvironment and paleoclimate.In this paper,the trace element and rare earth element of 22 samples(5.289-5.246 Ma)of mudstone from Y43 borehole in the Yahu area of the central Qaidam Basin are analyzed.The results show that the samples of Shangyoushashan Formation have obvious negative Eu anomaly,which indicate the sediments are mainly derived from the felsic crust by weathering.The paleo-salinity indices Sr/Ba and Th/U indicate terrestrial freshwater environment.The oxidation-reduction indices V/Cr,Ni/Co,U/Th and V/Sc indicate oxidation conditions.The paleoclimate indices Sr/Cu are consistent with the climatic trends indicated by Sr and Rb/Sr indicating the climate was generally humid with a fluctuating arid climate.Combined with sedimentary histogram and tectonic evolution history,we consider that the uplift of Tibetan Plateau and the regression of the Te⁃thys caused periodic arid climate since 9.7 Ma,but the climate in the early sedimentary period of Shangyoushashan Formation was still humid in the study area.

关 键 词：柴达木盆地中部 上油砂山组 地球化学 古环境 古气候 

分 类 号：P532[天文地球—古生物学与地层学]