四川甘洛则板沟铅锌矿床成因及找矿方向探讨

【作者】 曾令刚；

【导师】 顾雪祥； 王小春； 唐菊兴； 钟康惠；

【作者基本信息】 成都理工大学 ， 矿物学、岩石学、矿床学， 2006， 硕士

【摘要】 四川甘洛则板沟铅锌矿床位于扬子地台西缘甘洛—小江断裂上的甘洛成矿亚带北段。矿床赋存于震旦系灯影组顶部的灰黑色～灰白色白云质粉砂岩和砂质白云岩中，容矿构造为层间破碎带，马拉哈大断裂紧邻矿区东侧，矿带西南面和东南面有晚二叠纪峨眉山玄武岩出露。 前人资料和作者研究表明，围岩及上覆古生界地层含有较丰富的Pb、Zn及有机质，为后期雨水热液及混合热液活动成矿提供了物质基础。 通过对该矿床稀土元素、微量元素、硫、铅、氢、氧及碳同位素、流体包裹体的研究，作者认为，该矿经历了两种主要成矿作用：雨水热液活动成矿作用和与玄武岩有关的混合热液成矿作用。成矿物质主要来自上覆古生界地层和灯影组围岩。成矿流体主要来自大气降水补给。成矿流体盐度多为9.9～15.6wt.NaCl％，温度84～253℃，压力20～65.5MPa；铅、锌以PbCl₄^2-、ZnCl₄^2-及有机络合物形式迁移；促使Pb、Zn沉淀的主要原因是温度变化导致有机质还原硫酸盐的热化学反应（RST）及Pb、Zn有机络合物的分解，增加溶液中S^2-、Pb²⁺和Zn²⁺的浓度。 基于上述认识，结合矿带矿床特征及其分布特点，建立了该矿床的成矿模式，圈定了矿区外围3个找矿有利地段。更多还原

【Abstract】 The Zebangou Lead-Zinc deposit is situated in the north sect of Ganluo ore-forming subzone, Ganluo-Xiaojiang fracture zone in the western margin of the Yangtze platform.The deposit is hosted in ashen-atrament dolomitic powdery siltstone and sandy dolostone of Dengying Formation of Upper Sinian, the interbedded fracture zone is the structure of the deposit, Malaha large faultage pass by field east. Emeishan Basalt emerge in southwest and southeast of the ore-forming subzone.There are high content of Pb、 Zn and organic matter in the wall rack of the deposit and the upper Paleozic stratum, which would provide substance for ore-forming by the movement of later rainwater and mixed themic water.Through the study on the race earth and trace elements, the isotopes of sulfur, lead, hydrogen, oxygen and carbon, and fluid inclusions, the author concludes that the metallogenic material drived from the Dengying Formation and Palaeozoic Erathem; the main metallogenic fluid came from the meteoric water. The most ore-forming thermal solution is characterized by the middle salinity:9.9¹5.6wt.NaCl%,T=84 253°C, P=10⁶5.5MPa; Lead and Zinc were migrated in the form of PbCl₄^2- ZnCl₄^2- or organic-complex in the solution. The change of temperature lead to the thermochemical sulphat reduction（TSR） and the decompounding of organic-complexs which offer added S^2- 、Pb²⁺ and Zn²⁺, and promoting the sedimentation of PbS、 ZnS from the ore-forming thermal solution.By the cognition above, and combined with the deposits ’ feature and their distribution on the ore-forming zone, a ore-forming for the deposit established and the ore-prospecting direction near by this area are suggested.更多还原