Late Pleistocene epoch lake facies sedimentary characteristics, paleoplant-cover and definition of climate transformation since 17.4 ka B.P.Tanggula area, Qinghai

According to chronology research, sedimentary characteristics and interrelated botany analysis. It can make sure that three stages of paleo-plant cover evolve since Late Pleistocene epoch over Tanggula area, the paleoclimate had gone throngh the cyclical develop procress of dryness,cold-moist-dryness,cold.Meanwhile,the climate transformation event of wind-water had been defined from the Late Pleistocene epoch lake facies sediment, which occurred about 17.4 ka B.P.(TL).Corresponding plant cover characteristics also changed the stages from the main part of herbaceous-woody plant to the absolute advantage of herbaceous plant and low sporo-pollen zone appeared in the eolian deposite after 17.4 ka B.P.(TL).