柴达木盆地盐湖周边灌丛沙丘微量元素特征与环境意义

Trace Elements’ Geochemical Characteristics of Nebkhas in Qaidam Basin and Their Environmental Implications

中文关键词:  柴达木盆地  盐湖周边  灌丛沙丘  微量元素  地球化学特征

英文关键词:Qaidam Basin  Surrounding of salt lakes  Nebkhas  Trace elements  Geochemical characteristics

中文摘要:

      对柴达木盆地盐湖周边灌丛沙丘沉积物微量元素、粒度测试,并与其他体系沉积物对比,分析微量元素地球化学特征及环境状况。结果表明:1)微量元素以V、Cr、Zn、Rb、Sr含量较大,其中Sr含量最高,Rb次之；与中国黄土、新疆灰钙土相关系数R²为0.96,斜率分别为1.07和0.99,含量总体相似；Sr、U高于灰钙土和黄土,其中,Sr含量表现为灌丛沙丘>灰钙土>黄土,Rb、Sn、Cs、Pb、Th含量介于二者之间,其余元素含量均低于二者；其与中国沉积层元素丰度存在差异。2)Sc、V、Co、Ni、Cu、Cs、U与黏粒(<2 μm)和粉砂(2～63 μm)相关度均较高,而Ga、Rb、Pb主要受控于黏粒组分,Cr、Zn、Sr、Nb、Sn主要取决于粉砂组分；Y、Th与其他元素及不同组分无相关性；Rb/Sr比仅与Ga、Rb、Pb元素及>63 μm的砂组分呈极显著正相关,与其余元素相关度低或不相关,或极显著负相关。3)Rb、Sr分别反映了沉积物近地化学风化成壤作用和源区物理风化过程；Sr/Cu值介于15～20之间,Th/U值介于3.5～4之间,C.V值差异不大,元素垂直变异较小；总体表面灌丛沙丘沉积发育于极端干热环境,未发生明显还原作用。

英文摘要:

      Trace elements and grain-size of the sediments from nebkhas around salt lakes in Qaidam Basin were tested and compared with other sediments. The geochemical characteristics of trace elements and sedimentary environment were studied also. The results show that:1) The trace elements, such as V, Cr, Zn, Rb and Sr are higher in content, and the content of Sr was highest, Rb is the second. The correlations between nebkhas and Chinese loess, Xinjinag sierozem were very strong and R²=0.96, the line slope were 1.07 and 0.99 respectively.The content of Sr and U were higher than the sierozem and loess, and the content of Sr show nebkhas>sierozem>loess.The content of Rb, Cs, Pb, Sn and Th were between sierozem and loess, and the other elements are lower than the two. And trace elements of nebkhas are different from the abundance of the sediments from Chinese layers. 2) Sc,V,Co,Ni,Cu,Cs and U have high correlation with clay(<2 μm) and silt(2~63 μm), and the Ga, Rb, Pb are mainly controlled by clay, the Cr, Zn, Sr, Nb, Sn are mainly controlled by silt. Y and Th are not related to the other elements and sediment components. The values of Rb/Sr are significantly positive correlated with the elements(Ga, Rb, Pb) and sand composition(>63 μm), lowly relative or irrelevant to the other elements, or significantly negatively correlated. 3) The chemical weathering and the physical weathering process of sediments source are indicated by Rb and Sr respectively. The values of Sr/Cu are from 15 to 20, and the Th/U value are from 3.5 to 4, and the content of trace elements has little difference. The results show that nebkhas developed in the extreme dry and hot environment, and there was no significant reduction.