Quaternary palynological records and climatic signifiance of S9 borehole in Sanhe City of Hebei Plain

For exploring the evolution characteristics of vegetation and climate in eastern Hebei Plain since Pleistocene period, the authors in this paper studied the palynoflora of the S9 borehole in Dachang Depression. According to sporopollen distribution of S9 borehole, 6 sporopollen assemblages were divided from bottom to up. The assemblage I and II were broad-leaved mixed forests dominant by the coniferous, with assemblage III-Ⅵ were sparsely forested grassland vegetation, the whole area was dominant by savannah-type vegetation environment. Besides, the climate change regularity was restored based on the palynological assemblages. In Early Pleistocene, the climate of the study area was warm and semi-arid, and the climate became cold in the beginning of Middle Pleistocene, with warm and dry trends in general afterwards. In Late Pleistocene, the climate of the study area continued to get warm, with the transition from wet to dry. The evolving pattern of palynoflora in the study area was similar with environment change of other regions in North Central China, and is well consistent with climate change characteristics of East Asia, North Pacific and the Southern Hemisphere.