西藏羌塘北部地区晚二叠世地层再研究

Restudy on the Late Permian Strata in Northern Qiangtang Area,Tibet

西藏羌塘北部晚二叠世地层,主要分布在双湖办事处-热觉茶卡一带,称为“热觉茶卡组”,其下部为深灰色、灰绿色粉细砂岩、粉砂质页岩、夹生物碎屑灰岩、含竹蜓类、腕足类等化石;上部为黄灰色砂岩夹炭质粉砂岩、泥岩和多层煤层,含植物化石。上、下两部分之间为断层接触。根据1/25万玛依岗日幅区域地质调查的最新资料,其上部产大羽羊齿植物化石的陆相碎屑岩沉积与下部产竹蜓类动物化石的海相沉积,二者为连续沉积。通过古生物化石的研究与岩石地层学分析,将原热觉茶卡组拆分为两个组,保留下部含有竹蜓类等化石海相沉积为主的热觉茶卡组,将上部含植物化石的地层建立一新的岩石地层单位—黑土沟组,代号P3h。

The Late Permian strata,namely Raggyorcaka Formation,is distributed along the line from Shuanghu agency to Raggyorcaka area.The Formation comprises two parts divided by fault.The lower part is mainly composed of shale and carbonate containing fusulinids and brachiopods while the upper part is dominated by flora-bearing sandstone and mudstone.Acording to the new materials got from 1∶250 000 scale Mayigangri map,the upper terrestrial flora-bearing deposits conformably overlie the lower marine fusulinids-beari...