安山岩风化过程中元素行为——以豫西熊耳山地区为例  

Behavior of Major and Trace Elements During Weathering of Andesite: A Case Study of the Xiong'ershan Region,Western Henan Province

作　　者：马云涛[1] 龚庆杰[1] 韩东昱[1] 刘宁强[1] 袁玉涛[1] 佟依坤[1] 贾玉杰 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中矿资源勘探股份有限公司,北京100089

出　　处：《地质与勘探》2015年第3期545-554,共10页Geology and Exploration

基　　金：中国地质调查局地质调查工作项目(1212011120950);国家科技支撑计划课题(2011BAB04B09)联合资助

摘　　要：在风化过程中主量元素的风化行为可用风化指数来表征,但对在地球化学中更重要的微量元素的风化行为还缺少研究。本文研究了豫西熊耳山地区—安山岩风化剖面,发现花岗岩风化指数(WIG)也适用于安山岩风化过程的定量表征。基于上陆壳作标准绘制风化剖面样品稀土元素配分曲线时,发现风化过程稀土元素出现分馏现象,表现为富集中稀土;但基于球粒陨石作标准时,风化壳样品均具有相似的稀土配分曲线形态,即上陆壳是一种比球粒陨石更为敏感的稀土元素标准化标尺。牛头沟金矿区安山岩风化过程中部分微量表现出随风化程度增强而显著富集的特征,Au、Ag含量变化可达两个数量级以上,Pb、As、Hg可达一个数量级以上。Behavior of major oxides can be described by chemical indexes of weathering,while behavior of trace elements remains unclear,though it plays a more important role in geochemical exploration. This work focused on a regolith profile of andesite to investigate the behavior of both major and trace elements during weathering,which is located in the Niutougou gold deposit of the Xiong'ershan region,western Henan Province. The results suggest that the weathering index of granite( WIG) is also suitable to describe the weathering degree of the regolith profile developed over andesite. Fractionation of REE( or middle REE enriched more) is observed when REE pattern is plotted on upper continental crust( UCC),but no fractionation of REE( or similar REE pattern) occurs when REE pattern is plotted on Chondrite. Therefore,UCC is more sensitive than Chondrite when they are used as standard samples in REE pattern diagrams. Some trace elements enriched significantly with more extensive weathering in the regolith profile. Contents of Au and Ag of the upper samples in the profile are two magnitudes greater than those of the fresh andesite,and contents of Pb,As and Hg in the upper soils are one magnitude greater with respect to their fresh parent rock.

关 键 词：安山岩 元素风化行为 牛头沟金矿 熊耳山 豫西 

分 类 号：P512.1[天文地球—地质学] P595