新疆巴里坤湖粒度组分分解及其环境指示意义

选择位于西风影响区的天山东段巴里坤湖湖泊岩芯样品,对沉积物粒度组分进行经验正交函数(EOF)分解,并探讨各分量的环境意义.结果显示,EOF1组分与沉积物粒度小于2μm组分相关系数达0.64以上,并与代表区域有效湿度的碳酸盐氧同位素指标有很好的对应关系,故将EOF1解译为区域有效湿度的替代指标.EOF2组分与粒级为45-...

Decomposition of the Grain-size Component and Its Climate Implication from Lake Barkol, Xinjiang

A 426 cm core from Lake Barkol, eastern Tian Shan, provides the evidence of Holocene climate in Westerly dominated Asia. Here, we present a grain size component series decomposed by empirical orthogonal function and the chronology is based on radio carbon dating. The results show that the EOF1 component has a high correlation coefficient (0.64) with the volume percentage of the component less than 2 μm, furthermore it is similar to the evolution pattern of oxygen isotope from carbonate which is a proxy indicating the regional effective moisture, so the EOF1 component is an indicator of the effective moisture in the region. Modern dust grain size analysis from Barkol shows a peak percentage around 61.2 μm. Coincidently, the EOF2 component has a high positive correlation coefficient with the grain size ranging from 45 to 138 μm, which suggests that the EOF2 indicates the regional dust activity. EOF results suggested that the effective moisture was low and the dust activity was strong in mid Holocene, which was consistent with the mid Holocene arid interval occurred in the northern Mongolia Plateau. The enhanced Siberia high intensified the Westerly circulation and winter monsoon, and which could be the main reason for the arid and dusty mid Holocene climate in the research region.