A Comparative Study Of The Pollen Assemblages Between The East And West Basins Of Zhuye Lake During The Mid-Holocene

Pollen in lake sediments is an important proxy for reconstructing the paleo-environment. In Zhuye Lake, northwest China, the Holocene pollen records indicate variable environmental histories in different locations of the lake basin. Previous studies focused on the western lake basin, in the east part of the lake basin, the pollen assemblages were less reported. Lake carbonate sediments can show alkaline sedimentary environment, while alkaline environment has serious corrosion on pollen affecting pollen conserving.According to the relationship between carbonate and pollen concentration in lake sediments, we can explore whether the regional pollen conserving was affected by carbonate.In this research, we analyzed the pollen assemblages of the SKJ and JTL sections in the east part of the basin for conducting a comparative study of the pollen assemblages in the entire lake basin during the mid-Holocene. The result has showed that the high carbonate content and the high pollen concentration corresponded with each other in Zhuye Lake during the Holocene. The climate was warm and wet in Zhuye Lake during the period of lake expansion, while there is a large amount of pollen input, although alkaline environment has serious corrosion on pollen conserving. Therefore, the alkaline sedimentary environment was not enough to change the pollen concentration. The different mid-Holocene pollen assemblages in different location of the lake basin were not resulted by the pollen conserving. The results showed that the pollen assemblages were similar between the shores of the eastern lake basin and the central lake area, while the pollen assemblages of the SJC section were different from those of the QTH02and QTL-03sections. There were also disparities in pollen types between the eastern and western lake areas. The main reasons for these differences are as follows:the west-lake area was greatly influenced by the hydrodynamic conditions, and the pollen assemblage was affected by basin-wide vegetation types. The pollen assemblage for the eastern part mainly came from local and transported by wind; the sedimentary environment is relatively stable; therefore, the pollen assemblages there can reflect the mid-Holocene environment in Zhuye Lake, not for the entire drainage basin. Totally, sedimentary re-deposition effects caused by water disturbance and lake water waves are the main dynamic reasons for the different pollen records in the lake basin.