云南麻栗坪铅锌矿床成矿地质背景及成矿作用

Metallogenic geologic setting and mineralization process of the Maliping Pb- Zn deposit in Huize county,Yunnan

滇东北麻栗坪铅锌矿位于扬子板块西南缘活动大陆边缘,川、滇、黔铅锌成矿区之昭通—曲靖铅锌成矿带中部。大陆边缘局限盆地为区域铅锌矿化的有利岩相古地理条件,布格重力异常区域重力线稀疏、拐弯或有变异的部位,剩余重力异常零值或负异常线附近拐弯处及膨缩部位为该区域铅锌矿成矿有利部位;呈南北向带状分布的元素Pb、Zn、Ag、Sb、Hg、As及Ba中低温热液成因组合的组合异常,且与震旦系、寒武系及石炭系分布区域对应较好的地区,为铅锌成矿最有利地段。南北向的甘洛—小江断裂、北东向顺层断裂褶皱构造及北北东向为主的羽状裂隙系统分别为铅锌矿化主要的导矿、控矿容矿及次级容矿构造。麻栗坪铅锌矿均产于寒武系下统渔户村组,为热卤水沉积成因,后期经华力西晚期峨眉山玄武岩浆活动,热动力改变古地热场形成热水循环,产生叠加改造。

The Maliping Pb- Zn deposit located in the northeastern Yunnan Province,occur in the central part of Zhaotong-Qujing lead- zinc metallogenic belt which belongs to the lead- zinc metallogenic province among the boarder area of Sichuan,Yunnan,and Guizhou Province. The paper has summarized favorable conditions for lead- zinc mineralization as followings：（ 1） restricted basin located in the active continental margin of Yangtze plateas favorable lithofacies paleogeographic condition;（ 2） where the gravity bouguer line became thinning,bending,or varying,residual gravity anomaly near to zero or bending and swelling parts of negative gravity anomaly within the gravity bouguer gravity anomaly area;（ 3） geochemical anomalies of Pb- Zn- Ag- Sb- Hg- As and Ba element combination of low to medium temperature hydrothermal mineralization which are zonally distributed along north- south strikeand had better are correspond to the outcropped areas where Sinian,Cambrian and Carboniferous strata occur. The NS- trending Ganluo- Xiaojiang fault,NE- trending interlayer fractures and fold structures and NNE- trending dominated secondary feather fractures are the main conducting structure of the hydrothermal fluid,ore- controlling and ore deposition structure and secondary ore depositionstructures during lead- zinc mineralization respectively. The Maliping lead- zinc orebodies are mainly hosted in the Lower Cambrian Yuhucun formation,and the deposit genesis belongs to the sedimentary genesis by the hot brine fluid,then were reformed and superimposed by recycled hrdrothemal fluid resulted from the Emei basalt magma activity in the Hercynian period.