安徽铜陵新桥铜硫铁矿床成矿地质条件及矿床成因分析

Geological ore-formation conditions and genesis of Xinqiao Cu-S-Fe deposit, Tongling, Anhui Province

从地层、构造和矶头复式岩株与成矿的关系入手,对新桥硫铁矿床的成矿地质条件进行分析。研究结果表明:地层对成矿作用的有利性表现为提供了"硅—钙—硅"构造和由假整合面形成的层间破碎2种良好成矿环境;层间滑脱破碎带、岩体侵入接触带和这两者形成的复合部位是新桥铜硫铁矿床最主要的3种控矿构造;矶头复式岩株的闪长岩类岩石属于硅酸弱饱和类钙碱性准铝质岩石,其岩浆主要来源于上地幔,且在岩浆上升过程中受到地壳物质的混染;岩体中Cu元素强烈富集,其具备提供成矿物质的潜力;1号矿体主要矿物围绕矶头岩株呈现出与典型岩浆热液矿床温度分带相对应的特征。岩浆是区内成矿的重要因素,新桥铜硫铁矿床应是以接触交代作用为主形成的矽卡岩型铜硫铁矿床。

According to the relationship between the stratums,structures,Jitou rock strains in Xinqiao Cu-S-Fe deposit and the mineralization, the geological ore-formation conditions in Xinqiao Cu-S-Fe deposit were discussed. The results show that stratums provide favorable environment for mineralization, namely ‘Si-Ca-Si＇ structure and interlayer fracture zone from pseudoconformity, and that the main ore-controlling structures are decollement fracture zone between the layers,intrusive contact zone of rock mass and composite parts between the formers. Jitou rock strains are weak silicate saturated, vice-metaluminous and calc-alkaline, originated from upper mantle and was contaminated by crustal materials during diagenetic evolution process. Cu in Jitou rock strains is so rich that magma has the potential to supply metallogenic substances,and that the zoning characteristics of main minerals around Jitou rock strains in orebody No.1are similar to the temperature zoning characteristics of typical magmatic hydrothermal deposit. Magma is the important factor of the mineralization, and Xinqiao Cu-S-Fe Deposit is skarn-type Cu-S-Fe deposit because of contact metasomatism.