Early Jurassic sporopollen assemblages from the Toksun subbasin in the Turpan-Hami basin， Xinjiang and their significance

Abstract：74 species of spores and pollen of 53 genera are found in the Lower Jurassic deposits in the Toksun subbasin of the Turpan-Hami basin， northwestern China. Through an analysis of the changes in contents of typical general and species and dominant components， two sporopollen assemblages may be distinguished in ascending order as follows： the Osmundacidites - Protopinus - Cycadopites assemblage and the Cyathidites - Piceaepollenites - Cycadopites assemblage. According to the features of the sporopollen assemblages and comparison of related fossil assemblages in China and abroad， the age of the Badaowan Formation should be early Early Jurassic， and the age of the Sangonghe Formation should be late Early Jurassic. At that time the vegetation of the Toksun area consisted of such arbores as Ginkgo， Cycadopites and Coniferales， associated with herbs such as Filices. The paleoclimate should belong to the subtropical one.