贵州从江县大融砖厂新元古界浅变质岩现代风化壳剖面中微量元素分布特征与相关性分析

Trace Element Distribution Characteristics and Correlation Analysis of Modern Weathering Crust Profile of Neoproterozoic Epimetamorphic Rocks in Darong,Congjiang County,Guizhou Province

前人对贵州第四纪碳酸盐岩风化壳红粘土已经进行大量的地球化学研究,但贵州东部大片的新元古界浅变质岩分布区第四纪风化壳地球化学至今尚未被研究。作者以从江大融砖厂新元古界浅变质岩风化壳为研究对象,对该系统的微量元素分布状况进行研究,发现风化壳剖面具有与碳酸盐岩风化红粘土类似的特征,即上部发育褐铁矿层,底部富集Mn、Co、Mo、Cd、Cs、Ba、Tl、Pb等元素,pH值的增加对多种微量元素沉淀富集起至关重要的作用。母岩微量元素含量背景值低及岩石节理发育可能是研究剖面微量元素含量整体表现为亏损特征的主要原因。利用SPSS软件对大融砖厂风化剖面土壤中各种微量元素进行R型聚类分析,根据其相关性大小划分为四类。在聚类过程中,突出地表现出一条原则,即为表生环境中地球化学活动性相似的元素往往归为一类。

There is a lot of geochemical research on red clay resulting from weathering in the Quaternary weathering crust of car- bonate rocks in Guizhou Province. However, no research has been conducted on the Quaternary weathering crust geochemistry of expansive Neoproterozoic low-grade metamorphic regions in eastern Ouizhou. In this paper the authors take the Neoprotero- zoic low-grade metamorphic weathering crust at Darong Brickyard of Congjiang as the subject of study to explore the distribu- tion of trace elements in this system. Finally, it was discovered that this modern weathering crust profile and red clay resulting from weathering of carbonate stones show similar features that in the upper part of the weathering crust is developed limonite layers, and in the bottom Mn, Co, Mo, Cd, Cs, Ba, T1, Pb, etc. are highly enriched, The increase of pH value plays a vital role in deposition and enrichment of various trace elements. The main cause that the study profile shows low trace element con- tents integrally might be that the parent rocks have a low background level of trace element contents and developed diaclases. On the basis of the magnitude of correlation, trace elements in the earth of Darong Brickyard weathering crust profile are clus- ter analyzed by SPSS software. There is, in cluster analysis p, an obvious principle that trace elements with the similar geo- chemical motility in the supergene-environment are classified as the same group.