Barremian–Aptian palynological assemblages of Transbaikalia (Belaya Gora section, Chita region): An integrated approach to biostratigraphy and facies reconstruction

Research subject. Barremian-Aptian palynomorph assemblage of terrestrial and lacustrine genesis in the Belaya Gora (Semyon) section, Transbaikalia, Chita region. Aim. Based on integrated approach to palynomorph study, to determine the age of the sediments as well as the specific features of paleoflora and its relationship with climatic conditions, paleolandscape and transgressive-regressive fluctuations in the paleolake. Materials and Methods. Samples were processed by a standard technique using heavy cadmium liquid, hydrochloric and hydrofluoric acids. Results . Diverse assemblage of spores and pollen of terrestrial plants of the Turga type is defined, which is strongly dominated by gymnosperms and contains rare angiosperms that is consistent with data from other biofossils. Abundant microphytoplankton of lacustrine genesis is also present. The stages of low and high stands in the lake are determined based on quantitative dynamics of spores, pollen and microphytoplankton. Conclusion . Biofacies analysis of palynological material shows that the sediments were formed in shallow slow-flowing mesotrophic lake surrounded by rich forest vegetation with highly diverse conifers, which is typical for warm and humid climate. Specific features of terrestrial paleoflora and mesotrophic type of the Belogorskoye lake suggest an elevated, but not sharp relief on the surrounding areas. Biostratigraphic range of the section is defined as the Upper Barremian - Lower Aptian. Literature data show that the Barremian-Aptian palynological assemblages of the Turga type are well defined in central regions of Transbaikalia as well as in Mongolia and China.