摘要
长坑金银矿床为沉积岩中的微细浸染型金矿与交代型银矿构成的矿床组合,金、银矿化与碳酸盐和碎屑岩围岩的硅化蚀变关系密切并呈分带现象,矿石类型主要为含矿硅化岩。矿化温度主要在300～170 C之间,成矿流体的主要成分为K^-、Na^-、Ca^(2+)、Mg^(2+)、Cl^(-)。金属配合物的分配计算显示,金在成矿热液中主要以疏氢配合物迁移,而银、铁、铅、锌则以氯配合物为主,铁、铅、锌在成矿后期的中性-弱碱性环境下可转变为羟基和硫氢配合物。热液-碳酸盐岩反应模拟证实水-岩相互作用是银矿石形成的有效机制。矿物组合的溶解度分析表明,金、银矿物分别在早期弱酸性和后期中-碱性条件下沉淀富集,这是造成金、银矿体分离和分带的主要或有利因素。
The Changkeng gold-silver deposit is composed of sedimentary rock-hosted, disseminated gold deposit and replacement-type silver deposit. The mineralization of gold and silver is zoned and closely related to silicification of carbonate and clastic rocks, so siliceous ore dominates in the deposit. The mineralizing temperature ranges mainly from 300 C to 170 C, and K+ , Na ' , Ca2+ , Mg2+ , and Cl- are the major ions in ore-forming fluid. Calculation of distribution of metal complexes shows that gold is mainly transported by hydrosulphide complexes, but chloride complexes of silver, iron, lead, and zine, which are transformed into hydroxyl and hydrosulfide complexes under neutral to weak-basic circumstances in the late stage, predominated in the mineralizing solution. Computer modeling of reaction of hydrothermal solution with carbonate rocks has confirmed that water-rock interaction was the effective mechanism for the formation of silver ore. The solubility analyses demonstrate that the precipitation of gold and silver minerals that take place under weak acid and neutral to weak basic pH conditions, respectively, is the main or favourable factor for the ore zonation and separation of gold from silver.
出处
《地质学报》
EI
CAS
CSCD
北大核心
1998年第1期52-63,共12页
Acta Geologica Sinica
基金
中国科学院黄金办基金
博士点基金
关键词
金矿床
银矿床
成矿机制
热力学模拟
computer modeling
transport form of element
water-rock reaction
precipi- tation of mineral
gold-silver deposit
