Paleovegetation And Paleoclimate Of Pliocene For The Dongwenquan Basin In East Kunlun Mountains

The thesis studied the lacustrine deposits in Pliocence in Dongwenquan basin in the East Kunlun Mountains. Based on the theory and methodology of Sporopollen analysis and micropaleontology, a detailed study on three lacustrine sediment profiles in Pliocene was carried out, the Paleovegetation and Paleoclimate were restored and compared with those of in the Zada basin, Zhenquancuo lake basin and Qaidam Basin. The relationship between the evolution of Paleovegetation and Paleoclimate in the study area and the uplift of the Tibet was simply discussed as well in the thesis.The main results and conclusions obtained by this study are as follows:1. Through a comprehensive analysis of Pollen, the evolution of Paleovegetation in Pliocence was restored, which was: Coniferous forest grassland→Alpine coniferous forest vegetation→Sparse coniferous forest steppe vegetation or Grassland vegetation.2. Through a comprehensive analysis of Fossil Ostracods, the evolution of Paleovegetation in Pliocence was restored, which was: Cooler and dry→Warm and humid (Fluctuations between warm and cold there )→Cool and dry arid.3. Compared the evolution of Paleovegetation and Paleoclimate with those of in the Zanda Basin, Zhenquancuo Basin, Qaidam Basin and Dongwenquan Basin, the conclusions are made by follows: (1) Early to middle Pliocene:The type of vegetation in the Northern Tibet was mainly Coniferous forest grassland or Broad-leaved forest vegetation sparse shrub steppe and the climate was relatively cool and dry; The type of vegetation in the Southern Tibet was mainly Coniferous forest vegetation and the climate was relatively warm and humid. (2) Middle to late Pliocene: The type of vegetation in the Northern Tibet was Coniferous forest vegetation and the climate was warm and humid but with fluctuations between warm and cold. The type of vegetation in the Southern Tibet was Broad-leaved forest steppe vegetation and the climate was dry and cold. (3) Late Pliocene: Both in the Northern and southern Tibet, the type of vegetations was the same -- Shrub steppe or Grassland vegetation. The climate in both of areas was cold and dry. (4) With the uplift of the Tibetan Plateau, the vegetation in Pliocene was evoluted from Alpine coniferous forest to Shrub steppe and the climate became dry and cold from Warm and humid. However, the climate change in the Southern Tibet was earlier than that of in the Northern Tibet, which indicates that there are some differences in different areas during the periods of the climatic deterioration in Pliocene.4. Discussed the relationship between the evolution of Paleovegetationand Paleoclimate and the uplift of the Tibet. Conclusion is that the uplift of the Tibet Plateau is an obvious impact on the climate and environment in the study area. The overall positive correlation -- with the continuous increase in altitude, the general change trend of the climate and environment was cold and dry. But these two do not always linear, the evolution of climate and environment should also be a combination of factors. According to the Pliocene pollen of the measured profiles vertical distribution of vegetation height and the current plants indicators of environment, suggesting that the elevation of the Pliocene in Dongwenquan basin should not be less than 3300m.