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    豫西前河金矿热液蚀变地球化学研究

    Hydrothermal alteration geochemistry of the Qianhe gold deposit in western Henan Province

    • 摘要: 提要:含矿热液在迁移过程中与围岩发生了广泛的流体-岩石反应而引起热液蚀变。前河金矿区内主要的热液蚀变有钾长石化、青磐岩化、绢云母化、硅化、黄铁矿化、碳酸盐化和萤石化等7种类型;划分了6个蚀变-成矿阶段,即黑云母-钾长石阶段→青磐岩阶段→绢英岩阶段→黄铁矿-石英阶段→石英-黄铁矿阶段→碳酸盐-卤化物阶段,以及外、中、内3个蚀变带。5种典型蚀变岩的常量和微量元素分析表明,绢英岩化蚀变中,Si、K大量迁入,Pb含量大大增加,在∑REE有所降低的情况下HREE有所富集;δEu和δCe在各蚀变阶段均呈现负异常;这些现象可能是导致金沉淀的元素地球化学响应。各阶段成矿流体-岩石的交代特点在绿泥石单矿物的矿物化学成分变化上也有所反映。

       

      Abstract: Abstract:Hydrothermal alteration is caused by fluid-rock interaction in the migration process of the ore-bearing hydrothermal fluids. The hydrothermal alterations of the Qianhe gold deposit might be divided into seven types, namely potash feldspathization, propylitization, sericitization, silicification, pyritization, carbonation and fluoritization. The alteration-mineralization process and the alteration zones can be divided respectively into six stages and three zones, in order of botite-potash feldspar stage→propylite stage→phyllic stage→pyrite-quartz stage→quartz-pyrite stage→carbonate-halide stage, forming outer, central and inner zones. Analyses of major and trace elements for five typical altered rocks indicate that, during phyllic alteration, Si, K, Pb increased considerably and HREE concentrated a bit with the slight decrease of REE. Negative anomalies of δEu and δCe were present in each alteration-mineralization stage. These factors might be responsible for gold precipitation. The metasomatic characteristics of fluid-rock interaction at every ore-forming stage are also reflected in chemical composition variation of chlorite.

       

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