内蒙古东北部上二叠统林西组沉积环境

Sedimentary Environment on Upper Permian Linxi Group in Inner Mongolia

在前人研究的基础上,应用地球化学方法,对内蒙古东北地区上二叠统林西组的沉积环境进行了研究。林西组的岩性为灰黑色泥岩、粉砂质泥岩、页岩,灰色泥质粉砂岩、细砂岩。通过常量元素、微量元素和稀土元素的分析,发现林西组砂泥岩样品整体具有高SiO2、Al2O3、V、Zr、Ba,低P2O5、Mn、CaO、Cd的特点;通过沉积环境判别指标的分析,确定林西组为开阔的淡水环境,主要为陆相沉积体系,在其沉积初期为海陆交互环境。同时根据沉积构造和岩性组合,将林西组进一步划分为滨浅湖、半深湖—深湖的湖泊沉积体系和三角洲前缘、前三角洲的三角洲沉积体系。

In this paper, on the basis of previous studies, using geochemical method, the research was done on the Upper Permian sedimentary environment Linxi Group in northeast Inner Mongolia. The lithology in Linxi Group was black mudstone, silty mudstone, shale, gray muddy siltstone, and fine-grained sandstone. By analyzing the constant element, trace element and rare earth elements, it was found that the entire sand-mudstone sample had high SiO2, Al2O3, V, Zr, Ba, and low P2O5, Mn, CaO, Cd character. Through analyzing the discriminant index of the sedimentary environment, open freshwater was identified in Linxi Formation, mainly is the corresponding terrestrial facies, and belongs to marine-continental alternating environment during the initial stage of deposition. Based on the sedimentary structure and lithologic association, Linxi Formation can be divided into lacustrine and delta facies, and the lacustrine can be subdivided into coastal-shallow lacustrine and semi-deep and deep lakes, the delta facies includes delta front and prodelta.