Sedimentary facies and palaeogeography features of Nangqian Tertiary basin in Yushu district, Qinghai

Through studying features of sedimentary and stratigraphic paleontology in Nangqian Tertiary basin,the authors point out the climate at Early Tertiary in basin is tropical-subtropical and rainy,the basin is not more than 1 000 m above sea level.The sedimentary faces and palaeogeography discover that in early basin development sedimentary assemblage is fan-braided-delta-lake which reflects tectonic active;in mature basin development the sedimentary assemblage is river-lake-delta.