羌北三叠系康南组灰岩地球化学特征及对古海水的制约  

Geochemical characteristics of Limestone from the Triassic Kangnan Formation, North Qiangtang Basin(Tibet) and their constraint on the seawater

作　　者：屈李华 周晓颖 赵芳 赵同寿 Qu Lihua;Zhou Xiaoying;Zhao Fang;Zhao Tongshou(The Geophysical Team of Xinjiang Geology Mineral Exploration and Development,Changji,Xinjiang,831100,China)

机构地区：[1]新疆维吾尔自治区地质矿产勘查开发局物化探大队

出　　处：《新疆地质》2019年第4期479-487,共9页Xinjiang Geology

基　　金：国土资源部地质调查项目西藏盐湖锂钾资源调查评价（1212011120982）资助

摘　　要：为研究北羌塘三叠系康南组灰岩地球化学特征及沉积环境,对研究区灰岩进行全岩分析,探讨古气候条件及海水特征,反演灰岩形成的海水稀土分布模式。结果表明:样品主量元素含量变化较大;具富集Rb,K,Ba,Sr,U,Zr,Th、亏损Ni,Cs,V,Sc,Hf,Nb,Pb的特征;稀土元素总量较低,重稀土元素相对富集,δEu弱负异常,δCe呈明显负异常。主量元素特征反映样品受到陆源物质的混入且混入作用抑制了灰岩的形成;微量元素比值特征反映样品形成于氧化环境。微量元素特征图解反映样品为正常的海水沉积,δEu及δCe异常反映样品受到后期热液活动的影响;康南组灰岩反演海水稀土元素与正常海水稀土组成一致。The whole rock analysis were carried out for understanding the geochemical characteristics of limestone from Triassic(Kangnan Formation)and its geological background in North Qiangtang area.The paleoclimate and ancient seawater were analyzed,and the rare earth elemental distribution patters of seawater discussed respectively.The results show that major elements vary largely for different samples.The sample are rich in Rb,K,Ba,Sr,U,Zr,Th and poor in Ni,Cs,V,Sc,Hf,Nb,Pb.The rare earth elemental patterns show that limestone has lower total REE and HREE enrichment,and weak Eu depletions,evident Ce depletions.The correlation of major elements indicates that the sample is contaminated with terrestrial materials but this mixed material Inhibition of precipitation of limestones.The ratios of trace elements show that rock was formed in a dry oxidizing environment.In addition,the diagrams denote that the sample as normal seawater deposition,δEu and δCe anomalies indicate that the samples are affected by the late hydrothermal activity.The sample inversion of seawater the rare earth element is accordance to the rare earth element characters of normal seawater.

关 键 词：羌北 三叠系 灰岩 微量元素 沉积环境 

分 类 号：P595[天文地球—地球化学]