鄂尔多斯盆地白豹地区晚三叠世长4+5沉积期古环境研究

Study on Paleoenvironment of the Late Triassic chang4+5 depositional period of the Baibao area in Ordos Basin

白豹地区位于鄂尔多斯盆地陕北斜坡的中西部,晚三叠世长4+5沉积期发育了一套三角洲～湖泊相陆源碎屑含煤沉积建造。根据研究区28个泥岩样品微量元素的分析,利用沃克法(相当硼法)、亚当斯法(Admas)及元素比值法(Sr/Ba)推断出研究区长4+5沉积期为淡水沉积环境;利用铁矿物组合法和Fe^(2+)/Fe^(3+)比值法判断当时沉积环境为弱还原环境;通过元素组合法(Cu、Ba、Ni等)分析,认为研究区长4+5沉积期为滨湖～浅湖沉积环境;根据元素组合法(Fe、Mn、Cr、V、Ni等)和元素比值法(Sr/Ba、Fe^(3+)/Fe^(2+))分析,认为研究区长4+5沉积期为潮湿气候条件。通过对湖盆水体性质及古气候条件的推断分析,为研究区晚三叠世长4+5沉积期砂体的成因及分布提供了佐证。

Baibao area is located slopes in central and western part of the northern Shanxi in the Ordos Basin,in which a set of delta-lacustrine terrigenous clastic sediments with coal is found in the Late Trias- sic chang4+5 period.According to the trace element analysis of the 28 samples of mudstone from the study area,using the walker method (equivalent boron method),the Adams method and the elemental ratio method (Sr/Ba) conclude that it was the freshwater depositional environment in the period of chang4+5; using...