EARLY CRETACEOUS SPOROPOLLEN ASSEMBLAGES FROM THE B-D1 WELL IN THE BOR US AREA OF CENTRAL-SOUTHERN DAXINGANLING MOUNTAINS

With systematic studies on the sporopollen fossils discovered from the section of 22-255.70 m of B-D1 well in Bor Us area, central-southern Daxinganling Mountains, 47 genera and 65 species (including undefined species) are obtained. According to their palynomorphs, contents and variation characteristics, the sporopollen fossils are assigned to the Lycopodiacidites-Densoisporites-Piceaepollenites assemblage with geological age of early stage of Early Cretaceous. The host stratum is corresponding to the Baiyingaolao Formation. Based on the analysis on the growing environment of major species and their parent plants, it is inferred that the central-southern Daxinganling Mountains were in warm temperate-subtropical climate conditions during the early stage of Early Cretaceous. In the meantime, the appearance of a large number of xerophytes indicates the influence of drought but different from typical arid environment, which is possibly related to volcanic activity at the time.