微量元素分析在判别沉积介质环境中的应用——以鄂尔多斯盆地西部中区晚三叠世为例

以鄂尔多斯盆地西部中区晚三叠世样品中微量元素测试结果为基础,选用对沉积介质环境反映比较敏感的锶(Sr)、铜(Cu)、钡(Ba)、铀(U)、钛(Ti)、钒(V)、镍(Ni)等微量元素指标,分析研究区地层中微量元素含量及其比值与沉积介质环境之间的对应关系,进而探讨鄂尔多斯盆地西部中区晚三叠世的沉积介质环境。结果表明,鄂尔多斯盆地西部中区晚三叠世延长组长9-长7期基本为温湿气候且变得越来越温暖潮湿;长9-长7期为微咸水相的淡水环境,长7期盐度含量略有增加;长9、长8期水体的氧化还原条件比较正常,长7期变为厌氧环境;长9-长7期垂向上水体分层不强。

The application of trace elements analysis to identifying sedimentary media environment: a case study of Late Triassic strata in the middle part of western Ordos Basin

This paper deals mainly with sedimentary media environment of Late Triassic epoch in the middle part of western Ordos Basin through identifying the corresponding relationships between trace element compositions and sedimentary media environment on the basis of analytical results of some special trace elements such as Sr,Cu,Ba,U,Ti,V and Ni which are sensitive to sedimentary media environment.The results of the study show that the sedimentary media environment of Late Triassic epoch from Chang-9 to Chang-7 was warm humid climate in general and tended to become increasingly warm and humid in upward direction,indicating the brackish water phase of the freshwater environment with a slight increase in salinity of Chang-7.The redox condition from Chang-9 to Chang-8 was normal,while that of Chang-7 became anoxic.The vertical variation of water column stratification is not obvious from Chang-9 to Chang-7.