Paleovegetation Subei Basin XH-2 Holes And Ancient Climate Research Since The Pleistocene

There is a series of significant climate transition in the global climate transform of Middle Pleistocene, one is Middle Pleistocene Transition (MPT) and another significant climate change is Mid-Brunhes event (MBE). These transformation events in different regions of climate and vegetation change are the current global change research hotspot. Because of Subei Basin is in the northern edge of the China’s eastern monsoon triangle, so its vegetation and climate influenced by the monsoon. Then we choose it to conduct research and this can reveal the. well-being of sensitivity to fluctuations in climate and vegetation of the region during the Quaternary and the evolution evidence of East Asian monsoon. Taken from the5.81-80.84m continuous core at the upper section of the XH-2hole in the Subei Basin recorded climate change information since the middle Pleistocene. In this paper, we main analysis the pollen data of XH-2hole and then the initial establishment the evolution of the climate and vegetation transition at Middle Pleistocene.By the comparison of Arbos percentage data and climate of the deep-sea oxygen isotope and magnetic susceptibility of loess stratigraphic correlation, combined with14C and the loss Magnetic susceptibility data, we contrast the age and layer sequence from Mid Pleistocene of XH-2hole.Combines data processing and analysis, we divide the Pleistocene biostratigraphic into14pollen assemblage zones, given the limits of accuracy of the pollen assemblages with similar vegetation succession in the merger process, and finally divide into following several succession:80.84-75m, containing deciduous broad-leaved forest-75-53m, evergreen-deciduous broad-leaved forest-53-45m, deciduous forest-45-30m,evergreen-deciduous broad-leaved forest-30-10m, containing deciduous broad-leaved forest-10-5.81m, reeds vegetation.The deposition records the Subei Basin XH-2hole Since the middle Pleistocene shows significant cooling event occurred at MIS16and MIS12, resulting in a significant change in vegetation composition. At the MIS19-17period, the lush subtropical common deciduous broad-leaved species of Carya, Platanus, Juglans and lately morer deciduous broad-leaved Celtis all have a rapid decrease trend in the MIS16stage. Before and after MIS12period, Arbors percentage was significantly higher than the percentage of Herb percentage and then equal to or even lower than the percentage of Herb. The vegetation composition those fit warm and humid such as Quercus, Cyclobalanopsis, Liquidambar, Pterocarya are almost extinct in MIS16,then gradually prosperous during MIS15-13, rapid reduce during MIS12.This changes have a good contrast with loess L6, S5, L5.As can be seen from the pollen record, the climate of Subei Basin in0.45Ma have a significant change,10,0000years of ice volume cycle began to show strong, with deep-sea oxygen isotope records correspond well.