Abstract: The Pollen records from the Bayiquan profile in Lop Nur region, Xinjiang, are characterized by high content of herb pollen, especially that of A rtemisia and Chenopodiaceae pollen. According to the pollen assemblage, the pollen distribution of this period can be divided into three zones from the botton to the top of the profile： In zone 1 (6.8～5.2 m) the percentages of herb pollen are high (68. 6%～77.3%) and the quantity of Pinus pollen are large. These records suggest that the vegetation was sparse and the climate was temperate or dry at that time; In zone 2 (5.2～1.1 m), the pollen situation is similar to that in Taitema Lake region, the content of Pinus pollen decreases whereas that of A rtemisia pollen increases. These suggest that the climate was drier and warmer than that of zone 1 in this region. In zone 3 (1.1～0.0 m), herb pollen is the dominant one, and the percentages of A rteminsia, Chenopodiaceae and Pinus are 45.7%, 20.5% and 17. 5% respectively. These suggest that the climate was even more drier and warmer than that of zone 2. Based on the analysis on the pollen assemblage and and TL dating, the geological age of the Bayiquan profile is determined as about Late mid-Pleistocene to Early late-pleistocene. The results of pollen analysis suggest that there was a climate fluctuation during the late-middle Pleistocene. Comparing with the regional vegetation history, it can be calculated that the modern vegetation has developed from Early or Middle Quaternary.

Key words: Lop Nur region, Bayiquan profile, pollen assemblage, geological age