安徽铜陵狮子山矿田铜、金共生与分离的热力学研究  

Thermodynamic study of the Paragenesis and Fractionation of Copper and Gold in the Shizishan Orefield, Tongling, Anhui Province

作　　者：徐晓春[1] 楼金伟[1,2] 谢巧勤[1] 肖秋香[1] 梁建锋[1] 褚平利[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]安徽省公益性地质调查管理中心,合肥230001

出　　处：《地质学报》2011年第5期731-743,共13页Acta Geologica Sinica

基　　金：国家自然科学基金项目(40972063);国土资源部公益性行业科研专项(201011050-03)资助

摘　　要：狮子山矿田是安徽铜陵矿集区内最具代表性的大型铜金多金属矿田。矿田内铜、金矿床或矿体既各自独立产出,又相互共生或伴生,铜矿化和金矿化在时间上和空间上存在既共生又分离的现象。本文选择矿田内代表性铜矿床和金矿床开展系统的流体包裹体地球化学研究,并进行成矿流体中铜、金溶解度的热力学理论计算和分析,探索铜、金共生与分离的机制和制约因素。研究认为,狮子山矿田成矿热液流体中的铜主要以CuCl2-和CuCl0络合物形式迁移,铜的溶解度受热液中的Cl-浓度影响,铜的卸载沉淀主要受温度、pH值、fO2和fS2等因素控制;金主要以Au(HS)2-和Au2S(HS)22-络合物形式迁移,金的溶解度受热液中的总硫浓度影响,金的卸载沉淀同样受温度、pH值、fO2和fS2等因素控制。共存于同一成矿流体中的铜和金由于其络合物类型和溶解度的差异及其对物理化学条件变化作出的响应不同,铜在较高温度及偏酸性条件下即开始沉淀,而金则在较低温度和弱碱性条件下开始沉淀,因而导致铜和金的时空分离,进而分别形成铜矿床和金矿床。Shizishan orefield is the most representative large-scale copper-gold orefield in the Tongling ore-intensive district,Anhui Province.Copper deposits and gold deposits in the district exist individually or paragenetically.Copper and gold mineralization occurs in paragenesis or separation both temporally and spatially.This study carried out systematic geochemical research on fluid inclusions from typical Cu-Ag deposits in the orefield and calculated and analyzed the solubility of Cu and Au in the ore-forming fluids so as to probe the mechanism of separation and paragenesis of copper and gold and controlling factors.The research indicates that copper in the ore-forming fluids of the Shizishan orefield occurred mainly as Cu complexes CuCl-2 and CuCl0 which migrated.Copper solubility was affected by the Cl- concentration and unloading and precipitation of copper were affected by temperature,pH,fO2 and fS2.While gold occurred as the complexes Au（HS）-2 and Au2S（HS）2-2 to migrate and gold solubility was always influenced by the total sulfur concentration.The unloading and precipitation of gold was controlled by temperature,pH,fO2 and fS2.Due to the complex types and solubility difference,copper and gold in the same ore-forming fluid responded very differently to the physicochemical conditions.Copper precipitates in relatively acid condition at high temperature while gold in a weak alkaline condition at relatively low temperature,thus resulting in temporal-spatial separation and mineralization of copper and gold.

关 键 词：共生与分离 迁移形式 热力学理论 狮子山铜金矿田 安徽铜陵 

分 类 号：P618.51[天文地球—矿床学]