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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    南秦岭柞水−山阳矿集区金盆梁金矿床载金硫化物矿物学特征及成矿指示

    Mineralogical Characteristics and Metallogenic Indication of Gold−Bearing Sulfides in the Jinpenliang Gold Deposit, Zhashui−Shanyang Ore Cluster Area, South Qinling

    • 摘要: 金盆梁金矿床位于南秦岭柞水−山阳金多金属矿集区北部,矿体呈近东西向赋存于上泥盆统桐峪寺组的沉积建造中,受左行韧性断层控制。关于矿石矿物学与金成矿过程尚缺乏系统的认识。基于岩矿相学鉴定、背散射电子图像(BSE)、能谱(EDS)及电子探针分析(EPMA)等方法,查明矿石组构与载金硫化物毒砂、黄铁矿、辉锑矿及白铁矿的矿物学特征,探讨金的赋存状态与成矿物理化学条件,初步厘定矿床成因类型。结果显示,热液成矿期的金矿化以微细浸染型为主,可划分为黄铁矿−毒砂−硅化(Ⅰ)、石英−辉锑矿−白铁矿±锑氧化物(Ⅱ)及方解石−石英(Ⅲ)3个阶段。不同载金硫化物的“不可见金”赋存状态差异显著,由毒砂的晶格金Au+,到早世代黄铁矿(Py-1)的晶格金Au+−纳米金Au0,至晚世代黄铁矿(Py-2)和白铁矿的纳米金Au0。金属矿物组合由毒砂−黄铁矿至辉锑矿−白铁矿,成矿流体由较高温的相对自然金不饱和状态,逐渐演化为相对低温的自然金饱和状态。金盆梁金矿床形成于较高硫逸度的中高温、中浅成环境,属于卡林型金矿床。

       

      Abstract: The Jinpenliang gold deposit is located in the northern part of the Zhashui−Shanyang ore cluster area, South Qinling. The E−W trending main orebodies, occurring in sedimentary rocks of the Upper Devonian Tongyusi Formation, are strictly controlled by the left−lateral ductile faults. To date, there is still insufficient understanding of the ore mineralogy and gold mineralization processes. In this paper, we obtain data from a variety of experimental methods, such as petrographic identification, Back−Scattered Electron imaging (BSE), Energy Dispersive Spectrometry (EDS), and Electron Probe Micro−Analysis (EPMA), to determine the mineralogical characteristics of gold−bearing sulfides (arsenopyrite, pyrite, stibnite, and marcasite), and discuss the chemical states of Au and physicochemical conditions for gold mineralization. The results show that the micro−disseminated gold mineralization in hydrothermal period can be divided into three stages: pyrite−arsenopyrite−silicification stage (Ⅰ), quartz−stibnite−marcasite±antimony oxides stage (Ⅱ), and calcite−quartz stage (Ⅲ). The occurrence states of “invisible gold” vary greatly among different gold−bearing sulfides, from Au+ in arsenopyrite to Au+ and Au0 in early generation pyrite (Py-1), then to Au0 in late generation pyrite (Py-2) and marcasite. The metal mineral assemblage changes from arsenopyrite−pyrite to stibnite−marcasite, while the ore−forming fluid gradually evolves from relatively high−temperature solutions unsaturated with respect to native gold to low−temperature solutions saturated with respect to native gold. The Jinpenliang gold deposit is a Carlin−type gold deposit, which was formed in a medium−high temperature and shallow−moderate depth with logf(S2) ranging from −8.5 to −4.5.

       

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