罗布泊八一泉剖面孢粉组合及意义

THE SPORE-POLLEN ASSEMBLAGE AND ITS SIGNIFICANCE OF BAYI QUAN PROFILE IN LOP NUR, XINJIANG

罗布泊东部八一泉剖面出露近 7m厚的地层 ,从中系统进行孢粉组合分析 ,剖面可划分成三个孢粉组合带。通过多方面的综合分析和区域对比 ,确定其时代为中更新世晚期 -晚更新世早期 ,该时代的确定为该区第四纪地层划分提供重要依据。孢粉组合特征表明 ,罗布泊地区中更新世晚期气候以温干为主 ,略有波动。

The Pollen records from the Bayiquan profile in Lop Nur region, Xinjiang, are characterized by high content of herb pollen, especially that of Artemisia 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 (6.8～5.2m) 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(5.2～1.1m), the pollen situation is similar to that in Taitema Lake region, the content of Pinus pollen decreases whereas that of Artemisia pollen increases. These suggest that the climate was drier and warmer than that of zone 1 in this region. In zone 3 (1.1～0.0m), herb pollen is the dominant one, and the percentages of Arteminsia, 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.