The discovery of palynopollen assemblage from Wanbao Formation of East Ujimqin Banner in Xilingol City, Inner Mongolia, and its geological significance

Abundant sporopollen fossils, which include 38 genera and 82 species, were found for the first time from the upper part of Wanbao Formation in Guolebangou section in East Ujimqin Banner of Xilingol City, Inner Mongolia.In the Cyathidites-Quadraeculina-Neoraistrickia assemblage, the early Middle Jurassic sporopollen species are relatively commonly seen.According to the contrasting with things of other regions, this set of strata should be separated from the original Damoguaihe Formation of Cretaceous and assigned to early Middle Jurassic.Based on the study of the ecological habits of sporopollen assemblage of Wanbao Formation, it is held that the palaeovegetation types in the study area during this period were coniferous-leaved and broad-leaved mixed forest, and the paleoclimate belonged to the semi-arid to semi-humid subtropical climate, which was slightly humid.In addition, the features of sporopollen assemblage were very similar to those of the sporopollen assemblage in whole northern China during the first Jurassic heating event, which seems to have been the palaeovegetation response to the first Jurassic heating event in northern China.