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    陕西石泉县羊坪湾金矿床地质-地球化学特征及金的富集规律

    Geological and geochemical characteristics and gold enrichment regularity of the Yangpingwan gold deposit in Shiquan, Shaanxi Province

    • 摘要: 提要:羊坪湾金矿床是在南秦岭造山带石泉—汉阴北部地区继黄龙金矿床和鹿鸣金矿床开发之后近年来新发现的金矿床,对该金矿床的研究对于该区域找矿实践及金成矿理论研究具有重要意义。笔者通过野外调研和室内测试相结合对羊坪湾金矿床地质、地球化学特征及金的富集规律进行了研究。羊坪湾金矿产于下志留统梅子垭组(S1m)含炭二云母石英片岩中,目前矿区圈出南、北两条平行展布的金矿化蚀变带,在矿带内圈出3条平行展布的金矿体。金矿化特征为硅化、黄铁矿化。金粒度较粗,主要为明金,以粒间金、裂隙金等形式赋存。含炭二云母石英片岩夹石英岩互层有利岩性段和韧(脆)性剪切构造控制着金矿的产出。流体包裹体研究表明:均一温度为170~220℃,属中—低温;氢、氧同位素的特征显示,成矿热液中的水介质是以大气降水和变质分泌水为主的混合水。硫同位素的变化范围是7.5‰~11.7‰,说明成矿物质主要来源于地层。综合地质地球化学特征认为该矿床为沉积-改造型中低温热液矿床。

       

      Abstract: Abstract:The Yangpingwan gold deposit was found after the discovery of the Huanglong and Luming gold deposits in the northern Shiquan-Hanyin area of the Qinling orogenic belt. The study of regional gold prospecting and gold metallogeny is of great importance. Geological and geochemical characteristics were studied in this paper through field investigation and laboratory experiment. Gold mineralization occurs in schist of the Lower Silurian Meiziya Formation (S1m). The northern and southern ore-forming belts which contain three ore bodies have been delineated. Gold mineralization is characterized by silicon and pyrite. Gold exists mainly as visible gold between mineral grains or in cracks. Gold mineralization is controlled by schist strata intercalated with quartzite layer and shearing structure. Metallogenic temperature of fluid inclusions is 170-220℃, suggesting mesothermal-epithermal mineralization. D and O isotopes show that ore-forming fluids were derived from precipitation and metamorphosed water. S values vary in the range of 7.5‰-11.7‰, implying that metallogenic materials came from strata. Geological and geochemical characteristics indicate that the Yangpingwan gold deposit is a sedimentary-reformation type deposit formed at middle-low temperatures.

       

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