Pollen and spore assemblages ages and climate of Tuchengzi Formation in Qianjiadian Basin Beijing

In this paper, pollen and spore assemblages of the first and second members of Tuchengzi Formation in Qianjiadian Basin, Yanqing, Beijing, were studied an discussed.There are 12 genera, 8 species and 6 undetermined species of pollen and spore in the strata.The dominant pollen and spore assemblage isClassopollis spp.(over 90%), and secondary pollen is riblessbicapsular pollen of some conifers.Fern spores are very few, whose genus and species differentiation and content are much lower than those of gymnosperm pollen, accounting for only 2.13% of pollen and spore assemblage.The current pollen and spore assemblage is peak-time Classopollis assemblage.It is inferred that its age is early stage of late Jurassic.Based on the analysis of other fossils in the area, it is considered that, under the wholly arid or semi-arid climate conditions of Tuchengzi Period, there at least existed local lake climate.