微量元素分析在判别沉积环境中的应用——以柴达木盆地西部锶矿区富锶地层为例

摘要

沉积岩中的微量元素对沉积环境水介质的变化较为敏感,是研究沉积物沉积时古气候、古环境的有效手段.选取了对沉积环境介质较为敏感的锶(Sr)、钡(Ba)、铜(Cu)、铀(U)、钒(V)、镍(Ni)、钍(Th)等元素作为判别指标,对柴达木盆地西部上新统油砂山组、狮子沟组和更新统七个泉组三套富锶岩层的古气候和古沉积环境特征进行了研究.结果表明,柴达木盆地西部从油砂山组到七个泉组沉积时总体上为干旱的气候环境;湖盆水体的盐度较高,表现为咸水环境,且从油砂山组到七个泉组随着地层变新,盐度有逐渐增大的趋势;油砂山组、狮子沟组和七个泉组沉积时湖盆水体均表现为中等分层、湖水循环较为顺畅的氧化环境.%The trace elements in sedimentary rocks are sensitive to the change of sedimentary environments, which are effective means to study the paleoclimate and paleoenvironment during sediments deposition. In this paper, elements including Sr, Ba, Cu, U, V, Ni and Th are applied to investigate the paleoclimate and paleoenvironment of three sets of strontium-rich sedimentary rocks in the Miocene Youshashan Formation and Shizigou Formation, and the Pleistocene Qigequan Formation in the western Qaidam Basin. The results show that the western Qaidam Basin was generally dominated by arid climate from the Youshashan Formation to the Qigequan Formation; The salinity of the lake waters was high, showing saltwater environment, and from the Youshashan Formation to the Qigequan Formation, the salinity gradually increased; The lake water in the Youshashan Formation, Shizigou Formation and Qigequan Formation all showed moderate stratification and relatively smooth lake water cycle, indicating an oxidation environment.