投稿时间：2016-11-24
修订日期：2017-02-20
网络发布日期：2017-05-13
中文摘要:滇西北金顶巨型Zn-Pb矿田产于兰坪晚中生代-新生代盆地中北部,对其成矿作用机制仍存在分歧。跑马坪铅锌矿床是其北东部的一个大型隐伏矿床,由众多规模不等、呈筒柱状、大脉状及不规则囊状的矿体(群)组成。大量的地质填图及坑道观察表明,该矿床的形成严格受北西向逆断层破碎带的控制,矿体就位于云龙组(Ey)砂泥岩不整合面下伏的三合洞组(T3s)碎裂状灰岩、砂结灰岩质角砾岩内;断层破碎带中的矿化更强,而旁侧的次级裂隙多被砖红色砂泥岩充填。依据矿物组合及矿石组构特点,自矿体中心向外,依次可分为致密块状富锌矿带、脉状细粒硫化物矿化带、脉状胶粒状硫化物矿化带、方解石-天青石-铁氧化物矿化带和碳酸盐化带5个矿化带,各带之间多为渐变过渡关系。显微镜、扫描电镜观测和能谱面扫描分析发现,矿石中存在代表流体混合成矿特征的环-胶状构造及包含结构等显微组构,指示富含金属离子及硫酸盐的卤水与富含还原性硫的流体在高渗透性碎裂状灰岩或灰岩质角砾岩中混合而快速沉淀成矿。因此,逆断层控制的幕式流体混合作用可能是跑马坪铅锌矿床的重要成矿机制。
Abstract:The Paomaping Zn-Pb deposit is a large concealed deposit located in the northeastern segment of the Jinding giant lead-zinc orefield within the Late Mesozoic to Cenozoic Lanping Basin in Southwest China, which consists of numerous ore clusters with highly variable sizes. The ore genesis has remained enigmatic between syngenetic and epigenetic origin. Based on detailed geological mapping, tunnel logging and data synthesizing, the authors found that the tube columned-, large vein- and irregular capsular-type orebodies are hosted in the fracture-shaped cataclastic limestone and sand-cemented limestone-breccia of the Upper Triassic Sanhedong Formation (T3s), adjacent to the unconformity between the Sanhedong Formation and the Paleogene Yunlong Formation muddy siltstone and mudstone (Ey). Associated mineralization was controlled by NW-trending reverse faults, some secondary fractures of the reverse fault are filled with brick-red siltstone-mudstone, whereas metals mineralization exclusively occurs in the main fractures zone. Field observations identified five mineralization zones with different mineral assemblages and ore textures surrounding each orebody. Outward from an orebody, these zones are compact massive Zn-rich orebody, vein-like fine-grained sulfides mineralization, vein-like colloform sulfides mineralization, calcite-celestine-iron oxides, and carbonations zones, respectively. The boundary between two nearby zones is always gradual. Microscopic and electron scanning microscopic observations about ore micro-textures checked by energy spectrum area scanning reveal many zonal colloform and poikilitic textures. The textural relationships indicate that the multistage fluids mixing processes once took place within pores and fractures of the high porous and permeable limestones and limestone breccias. Zonal colloform textures of sulfide-sulfate-carbonate minerals were induced when metalliferous fluid containing SO2-4 was mixed with another kind of fluid with reduced sulfur trapped in porous limestone, and the crystal seeds of the sulfide-sulfate-carbonate minerals nucleated rapidly and grew rhythmically. Therefore, the Paomaping Zn-Pb polymetallic mineralization might have been formed with the multistage fluids mixing controlled by NW-trending thrust faults. On such a basis, the paragenetic sequences of a single mineralization pulse were established.
keywords:geology micro-textures multistage fluids mixing ore-forming processes Paomaping Zn-Pb deposit in Jinding Lanping Basin
文章编号：
中图分类号：P618.42;P618.43
文献标志码：
基金项目:本文受到国家重点研发计划“深地资源勘查开采”专项“青藏高原碰撞造山成矿系统深部结构与成矿过程”课题（编号：2016YFC0600306-6）、国家自然科学基金项目（编号：U0933605、41373049、41302073）、中国地质调查局地质调查项目（编号：1212011121065、12120114064302、1212011020000150011）和教育部博士点基金项目（编号：20125314110006）的联合资助
引用文本：
余静,薛传东,杨天南,侯增谦,宋玉财,向坤,梁明娟,王红岩,廖程,唐靓,来瑞娟,杨天云露,杨献珍,刘星.2017.兰坪金顶跑马坪铅锌矿床幕式流体混合成矿作用——矿石组构证据[J].矿床地质,36(2):391~411YU Jing,XUE ChuanDong,YANG TianNan,HOU ZengQian,SONG YuCai,XIANG Kun,LIANG MingJuan,WANG HongYan,LIAO Cheng,TANG Jing,LAI RuiJuan,YANGTIAN YunLu,YANG XianZhen,LIU Xing.2017.Mineralization resulting from multistage fluids mixing at Paomaping Zn-Pb depo sit in Jinding,Lanping Basin,northwestern Yunnan Province:Evidence from ore micro-textures[J].Mineral Deposits36(2):391~411
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