ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    甘肃文县阳山特大型金矿田微量元素特征及其找矿意义

    Elemental Geochemistry and Significance of Prospecting for Yangshan Super-Large Gold Deposit, Gansu Province

    • 摘要: 甘肃省阳山金矿田位于川、陕、甘交界的金三角地区,是近年发现的特大型微细浸染型金矿床。目前发现的4个矿段(床),均赋存于泥盆系三河口组浅变质碎屑岩、碳酸盐岩地层中。矿田受安昌河-观音坝断裂带控制,矿体产于断裂带内褶皱翼部的次级剪切带或断裂中。元素地球化学研究表明:Au、As、Hg、Bi等元素在阳山矿田表现出强烈富集的特征。矿石微量元素分析发现阳山金矿田成矿物质主要来源于岩浆岩。相关分析揭示矿区微量元素主要有Au-As-Sb-Hg和Ag-Mo-Zn两种组合,Au与Hg、As、W、Sb等元素呈明显正相关。空间上Au与Hg、As、W、Sb等具有明显共消长关系。综合分析认为阳山金矿成矿物质主要来源于岩浆岩;Au-Hg-As-W-Sb可作为找矿的指示元素。元素比值特征显示矿体整体剥蚀较浅,目前地表出露应为矿体头部或中上部,且由东向西剥蚀程度逐渐加深,反映向深部矿体应还有较大成矿远景。

       

      Abstract: The Yangshan gold deposit recently found in south Gansu province is a supper-large finegrained,disseminated type deposit in China.Four ore segments found by now in the deposit all occurred in the Devonian low grade metamorphic sandstone and limestone.The ore occurrences are structu rally controlled by the Anchanghe-Guanyinba fault zone and orebodies usually exist in the secondary shear zones and faults of the folds in the Anchanghe-Guanyinba fault zone.The orebodies in lenticular or veinlike forms are spatially related to a plagioclase granite.Pyrite and arsenopy rite are the main metallic minerals,and native gold can usually be seen in pyrite,arsenopy rite and clay minera ls as micrograined inclusions (2~3 μm).Trace elements analyses from samples from vertical and transverse sections of the deposit showst ronglyen riched Au,Hg,As,Bi and Sb in the ore and a positive correlation among the elements.This indicates that the Au,Hg,As,Bi and Sbtogether represents amajor element association for the deposit.Moreover,the analyses suggest that oreforming materials was derived from magmatic rocks and Au-Hg-As-W-Sbcan betreated as an indicator for prospecting.We argue,by the ratios of some indica to relements that the ore deposit has been only eroded to amiddle-upper level,and the denudation,fromeast to west,becomes stronger.Therefore,a much richer deposit could be seen at depth of the deposit.

       

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