摘要:
里伍铜矿床是产于江浪穹窿的中型富铜矿床,其磁黄铁矿的成分和结构对矿床成因有重要的指示意义。基于对矿床地质特征的认识,采用偏光显微镜、扫描电镜能谱分析、X射线衍射等方法,对主矿体内不同构造类型矿石中的磁黄铁矿的化学成分和结构进行了分析。结果表明,矿体内部只产出六方磁黄铁矿,Fe原子含量百分比为48.63%~47.99%,其成矿温度高于304℃;矿体边部同时存在六方和单斜磁黄铁矿,Fe原子百分比为45.97%~47.54%,成矿温度迅速降低至254℃以下。结合磁黄铁矿标型特征和矿床地质特征,推断里伍铜矿床是在原始矿胚发生变形变质活化的基础上,经历了燕山期中高温热液叠加改造而富集成矿。
Abstract:
The Liwu copper deposit is a medium-sized copper-rich copper deposit hosted in the Jianglang metamorphic core complex dome in Jiulong, western Sichuan. The present paper deals with the chemical compositions and structural types of pyrrhotite from the Liwu copper deposit based on the microscopic examination, energy spectrum analysis and X-ray diffractional analysis. The analytical results show that there occurs only hexagonal pyrrhotite in the inner part of the copper deposit, with the Fe atomic percentages ranging between 48.63% and 47.99% and metallogenic temperatures higher than 304℃. On the contrary, both the hexagonal and monoclinic pyrrhotite are observed in the outer part of the copper deposit, with the Fe atomic percentages ranging between 45.97% and 47.54% and metallogenic temperatures lower than 254℃. It is inferred from the typomorphic characteristics of pyrrhotite and geological characteristics of the copper deposit that the Liwu copper deposit resulted from the activation caused by deformation and metamorphism in original source beds, and superimposed reworking of moderate-to high-temperature hydrothermal solutions during the Yanshanian.
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