塔里木盆地南缘沉积物磁化率、δ13C与粒度及其气候环境意义

本文研究表明,塔里木盆地南缘湖沼相沉积物质量磁化率与碳酸盐δ¹³C呈正相关关系,与粒度参数中056～3557μm各组分呈显著负相关,其中同1783～3170μm部分负相关性最为显著;与5637～2244μm之间各组分显著正相关,其中与7096～200μm各组分正相关性最为显著。其气候环境背景与意义表现为:在寒冷期中,δ¹³C偏轻,相对湿度和植被盖度增加,地表侵蚀减弱,只有较细物质才能向湖泊沼泽搬运加积,地表氧化环境减弱,磁化率减小;而在温暖期中,则相反。在区域对比基础上,根据上述指标将近40ka以来此地区气候环境变化划分了8个阶段。本文的各种指标（特别是粒度指标）与GreenlandGISP2冰芯δ¹⁸O记录之间有很好的吻合,表明研究区近40ka以来的气候与环境变化可能具有全球背景。

The correlation and climatic significance of the mass susceptibility, carbonate δ13C and grain size revealed from a historic sediment in the southern margin of Tarim Basin

Study of a historic sediment in the south margin of the Tarim Basin, where is influenced by the Westerlie force evidently, shows that the mass susceptibility correlates positively with carbonate δ¹³C and strongly with the components of 56.37-224.4μm(especially with components of 70.96-200μm), but correlates negatively with the components of 0.56-35.57μm (especially with components of 17.83-31.70μm.). The correlation among three proxies bears profound significance of climate and environmental changes. When temperature declined in the extreme arid area, the relative humidity increased greatly, resulting in restrains of evaporation and prosperity of vegetation, protecting the land surface from erosion, and only relative finer debris can be carried to deposit in lake, carbonate δ¹³C declined. Less oxidation strength during a relatively cold period led to lower mass susceptibility. Conversely, when temperature increased, relative humidity declined sharply and resulted in increase in evaporation, the vegetation cover reduced so that the erosion intensity on the land surface increased, leading to coarser component being loaded and deposited in lake and rise in carbonate δ¹³C. Strengthened oxidation during a relatively warm period resulted in an increase in mass susceptibility. Based on the interpretation of the proxies and widely regional comparison, this paper identifies 8 characteristic climatic periods during the last 4.0ka. Most significantly, the similarity which can be observed between the fluctuation of climate proxies in this paper (especially the proxies of grain size ) and the Greenland GISP2 ice core δ¹⁸O record shows that climate change of the studied area may have global background, and on the other hand, it also incarnates evident regional characteristics.