北疆晚更新世以来植被与气候演化的初步研究

PRELIMINARY STUDY ON VEGETATIONAL AND CLIMATIC EVOLUTION IN NORTHERN XINJ—IANG SINCE THE LATE PLEISTOCENE

本文根据5个剖面总的孢粉分析结构和^(14)C数据,应用数理统计方法,结合孢粉图式特征,将北疆晚更新世以来的古环境演化划分为7个阶段。同时探讨了各阶段的植被景观特征,并由此推断各时期古气候环境经历了冷湿——暖干——冷湿——偏冷偏湿——热干——偏凉略干——温干的演变过程。其中1～3阶段为晚更新世,4～7阶段属全新世。

Based on the sporo—pollen analysis and ^(14)C dating from five drillings and sections, the spore— pollen assemblages array survey in the Northern Xinjiang since the Late pleistocene is drawn out, and seven comprehensive spoio—poilen zones are divided. Thus the ancient vegetational evolution process induced to seven stages. Stage Ⅰ and Ⅲ Correspond to two glacial eplches in the Late Pleistocene separately, when the climate was cold—humid and the main vegetation forms on the piedment plain are shrub—grasslands and meadow steppe. Stage Ⅱ is inter- glacial epoch. The climate was dry—hot, the ground layer was siccideserta. The arrival of Holocene is in the stage Ⅳ. Under a cooler and slightly humid climate, the ground covered by grasslands, Stage Ⅴ was Atlantic Period. At that time, Xinjiang was extremely hot and dry, and emerged siccideserta and barren desert landscape. Then the gragsslands flora was recovered for a time in stage Ⅵ. The environment was similar to that in nowadays since stage .Dominated by the continental climate, Xinjiang has the special accompany state of dry—wet and cold—warm since the Late Pleistocene, which is contrary to that in Eastern China. Judged by the result of sporo—pollen analysis, dry—hot or cold—humid is the general pattern of climate variation in the Northern Xinjiang since the Late Pleistocene, despite there is the possibility that warm—wet or cold-—dry climate may dominant Xinjiang in some short periods.