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铜陵狮子山矿田金矿床和铜矿床矿石稀土元素地球化学

徐晓春, 赵丽丽,谢巧勤,褚平利,房海波,王文俊   

  1. 合肥工业大学 资源与环境工程学院,合肥 230009
  • 收稿日期:2009-03-20 修回日期:2009-03-20 出版日期:2009-03-20 发布日期:2009-03-20

Rare Earth Elements of Ores in Gold Deposits and Copper Deposits of Shizishan Ore-Field, Tongling Region, Anhui province

XU Xiao-chun , ZHAO Li-li , XIE Qiao-qin , ZHU Ping-li , FANG Hai-bo , WANG Wen-jun   

  1. School of Resources and Environment Engineering, Hefei University of Technology, Hefei 230009, China
  • Received:2009-03-20 Revised:2009-03-20 Online:2009-03-20 Published:2009-03-20

摘要: 在全面收集前人有关安徽铜陵狮子山矿田主要矿床矿石和蚀变岩石稀土元素分析结果的基础上,对比研究了矿田内金矿床和铜矿床的稀土元素地球化学特征。研究表明,金矿床和铜矿床矿石和蚀变岩石的稀土元素组成、轻重稀土比值和(La/Yb)N 值等特征参数承袭了矿区岩浆岩的特征,显示成矿物质的来源以岩浆来源为主,富集地壳组分,反映在成矿过程中深部热液对已固结岩浆岩的淋滤萃取作用和对沉积围岩的叠加改造作用,成矿作用与岩浆作用密切相关;不同成矿阶段和不同类型矿石或蚀变岩石的REE 特征反映REE 的来源和演化可能与成矿金属元素的来源及其富集成矿机制相一致。此外,金矿床和铜矿床矿石稀土元素地球化学行为亦显示出明显的差异性,铜矿床矽卡岩阶段矿石比石英硫化物阶段矿石相对低的REE 含量,以及部分矽卡岩矿石具有La,Ce 明显亏损的富集LREE 折线型配分模式,反映铜矿床这部分矽卡岩具有岩浆成因的特征;而金矿床和部分铜矿床中的矽卡岩及矽卡岩型矿石则以热液交代成因为主;金矿床和铜矿床Eu异常特征则反映了其成矿热液流体起源压力的差异及流体性质的阶段性演化。

Abstract: The REE data of ores, altered rocks and related rocks, and minerals in gold and copper deposits in Shizishan ore-field of Tongling region are collected to compare and discuss the differences of REE geochemical characteristics between gold deposits and copper deposits. The magmatic rocks, ores and related altered rocks in gold and copper deposits have similar chondritenormalized REE patterns, LREE/HREE and (La/Yb)N values, which displays that the ore-forming elements mainly come from the magmatic rocks, and are rich in crust materials. The deep ore-forming hydrothermal fluids may gain REE and ore-forming elements by leaching the crystallized magmatic rocks, and then superimpose and reform the sedimentary rocks. The mineralization is closely associated with magmatism. The REE geochemical characteristics in different stages and in different kinds of ores and altered rocks imply that the origin and evolution of REEs is closely related with that of ore-forming elements. On the other hand,REE geochemical characteristics of ores in gold and copper deposits also have significant differences. The REE contents in ores are lower in skarn stage than in quartz-sulfide stage. The REE distribution patterns of some skarns and skarn ores are LREE enriched, but with La and Ce depletion, which indicates a magmatic origin of these skarns and skarn ores in copper deposits;while the skarns in gold deposits and the other skarns in copper deposits were formed by metasomatism. The δEu values of the ores indicate that the ore-forming hydrothermal fluids had different pressures and different evolutionary features in different mineralization stages.