南疆地区历史时期气候与环境演化

Paleoclimatic and Paleoenvironmental Changes in Southern Xinjiang during Historical Period

通过塔克拉玛干沙漠南缘具有较高分辨率的尼雅剖面记录多指标的综合研究 ,结合南疆地区其他地质记录和历史资料 ,恢复了南疆历史时期 (近 40 0 0年 )以来气候与环境演化的特征与序列 ,共划分出 3个相对冷湿期和 3个相对暖干期。结果表明 ,此地区气候环境的演化在冷暖变化序列上基本吻合于我国东部地区 ,而在干湿波动上则具较为显著的西风型环境演变特征。同时还发现 。

Based on synthetic researches of multi index geological records of Niya section, which are of high resolution in southern margin of the Tarim Basin, together with other geologic records in southern Xinjiang, this paper has reconstructed the history of paleoclimatic changes in this region since about 4 0 ka BP) During the last 4000 years, the area of southern Xinjiang has experienced alternations of relative cold wet and relative warm dry periods Three evident cold wet periods and three warm dry periods are identified (1)Relative cold wet period (4000 3450 a BP) Multi geologic index and pollen assemblege in the layer of Niya profile shows the characters of aridity (2)Relative warm dry period(3450 2500 a BP) The period corresponds to the Shang, Western Zhou dynasties and Spring and Autumn Period The result of study shows that this period is a relative warm dry period (3)Relative cold wet period(2500 1900 a BP) The phase likely corresponds to the Warring States, Qin and Han dynasties The peaks of the curves of geochemical element ratios, δ 13 C and Xlf, as well as A/C all indicate a relative wet character, and coincides with the research results of other areas in Xinjiang (4)Relative warm dry period in climate(1900 1400 a BP) The phase corresponds to the later part of the Western Han Dynasty and most of the Wei and Jin as well as Northern and Southern Dynasties The changes of the geochemical element ratios,δ 13 C and Xlf all display evident warm dry characters (5)Relative cold wet period in climate(about 1400 1000 a BP) The period includes Sui and Tang dynasties (581 907AD) and early Song Dynasty Although several slight cold wet and warm dry fluctuations appeared, it was mainly cold wet in climate, the paleoclimate began to be desiccated in the later period (6)Relative warm dry period in climate(1000 a BP present) The average values of P/Mn, SiO 2/Al 2O 3, Na 2O/K 2O and δ 13 C are high,which imply that the region has entered a relative steady warm dry period