Geochemical characteristics and environmental significance of Talede loess–paleosol sequences of Ili Basin in Central Asia
Geochemical characteristics and environmental significance of Talede loess–paleosol sequences of Ili Basin in Central Asia
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DOI：
10.1007/s12665-013-2323-1
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发表时间：
2013-03
影响因子：
2.8
通讯作者：
Wenxiang Zhang;Zhengtao Shi;Guangjie Chen;Yong Liu;J. Niu;Q. Ming;Huai Su
中科院分区：
文献类型：
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作者：
Wenxiang Zhang;Zhengtao Shi;Guangjie Chen;Yong Liu;J. Niu;Q. Ming;Huai Su
中亚黄土-古土壤存款是西风带第四纪古气候演变的敏感指示器，为研究第四纪气候历史及其与全球气候变化的关系提供了重要信息。通过对伊犁盆地塔勒德黄土-古土壤序列密集采样地层元素组成的地球化学分析，结果表明：常量元素含量以SiO2最高，其次是Al 2 O3。常量元素的丰度顺序为：SiO2> Al 2 O3> CaO > Fe 2 O3> MgO > Na 2 O> K2 O。微量元素Rb、Sr、Sc、Ni、Cu、Ga、Mo、Y、Pb、Th在古土壤层（S 0、Sm、S1）和黄土层（L1）中相对于下伏黄土层（L2）富集，但Zr、Cs、Nd和La在古土壤层中含量相对于下伏黄土层（L2）富集。富集因子、Rb/Sr比值、淋溶系数（Ki）和化学风化指数等地球化学指标在塔勒德黄土-古土壤存款中均无明显分异。结果表明，间冰期伊犁盆地的化学风化作用较弱，蒸发量较大，有效水分较低，与黄土高原地区相比，气候较弱，为暖干气候。此外，伊犁地区黄土中富含片状矿物，表明该黄土可能来自中亚沙漠，并与中亚地区广泛的干旱化密切相关。
The loess–paleosol deposit in Central Asia is a sensitive indicator of the evolution of the quaternary paleoclimate in the Westerlies, providing insight into the quaternary climate history and its relationship with global climatic changes. Based on the geochemical analysis of elemental composition of densely sampled strata from Talede loess–paleosol sequence in the Ili Basin, the results showed that SiO2had the highest major elements content, followed by Al2O3. The order of compositional abundance of major elements was generally as follows: SiO2> Al2O3> CaO > Fe2O3> MgO > Na2O > K2O. Trace elements (i.e. Rb, Sr, Sc, Ni, Cu, Ga, Mo, Y, Pb, Th) in the paleosol layers (i.e.S0,Sm,S1) and the loess layer ofL1were enriched relative to underlain loess (L2) horizons, except for the contents of Zr, Cs, Nd, and La in paleosol layers. All of geochemical proxies, such as enrichment factor, Rb/Sr ratio, eluvial coefficient (Ki) and chemical weathering index, display no obvious differentiation in the Talede loess–paleosol deposit. The results indicate that the weak chemical weathering, greater evaporation and low effective moisture in Ili Basin, are to a degree weaker than those in the China Loess Plateau and the climate was warm–dry during the interglacial period. In addition, the loess of Ili area is rich in schistose minerals and implies that the loess may come from the deserts of Central Asia and it may be closely related to the widespread aridification of Central Asia.