亚速海地区Chumbur-Kosa黄土剖面元素地球化学特征

Geochemical characteristics of elements in Chumbur-Kosa loess-paleosol sequences in the Sea of Azov

选取俄罗斯南部亚速海地区的Chumbur-Kosa(CK)黄土剖面作为研究对象,系统地分析了剖面中常量地球化学元素质量分数以及它们在风化过程中的迁移变化规律,并通过常量元素的相关比值参数(化学蚀变指数、w(Na)/w(K)和残积系数)对剖面的风化淋溶程度进行了初步分析.结果表明:CK剖面主要物质组成以Si、Fe、Ca为主,三者质量分数平均值的总和达到77.61%,常量元素w(Si)>w(A1)>w(Ca)>w(Fe)>w(K)>w(Mg)>w(Na);相对于上部陆壳的平均值,CK剖面呈现贫Na富Ca的特征;常量地球化学元素氧化物以及参数比值与CK剖面各地层特征有较好的对应关系.S2古土壤层中的常量元素氧化物及参数比值呈现出与其他古土壤层相反的变化,产生这种现象的原因可能是在L2沉积初期,由于降水作用导致土壤湿度增加,使活动性元素向下淋溶,并在S2中发生富集;CK剖面尚处于早期以去Ca、Na为主的初级风化阶段,风化程度弱.亚速海地区黄土化学风化过程主要受气候条件的影响,其中降水因素可能起着更为重要的制约作用.

The Chumbur-Kosa（CK） loess-paleosol sequences were taken as the study subject.Major geochemical elements and the element migration orders of the Chumbur-Kosa section were analyzed.According to the chemical indexes of alterations,w（Na）/w（K）,eluvial variations,the weathering intensity of the CK section was studied and the results showed that Si,Fe and Ca were the main elements in the CK profile.The average content of their total concentration accounted for 77.61%of the whole.The sequences of element content were w（Si）w（Al）w（Ca）w（Fe）w（K）w（Mg）vv（Na）.Characterized by the average content of the upper continental crust,the section was obviously enriched in Ca and depleted in Na.The ratio parameter of geochemical elements and stratigraphic characteristics had a good relationship in the CK section.Compared with other paleosol strata in the CK section,the content of major element oxide and the ratio of parameter in L2 showed the opposite variations.The increasing precipitation resulting in the Ca,Mg and Na leaching into L2 might be the main reason for the enrichment that had occurred in S2.The CK section was still being an early stage of Na and Ca depleting period for the chemical weathering degree was weak.Further analysis showed that climate condition（in particular,the precipitation） might have a vital influence on the chemical weathering formation in Sea of Azov.