云南白秧坪银多金属矿床形成的地球化学机制

【作者】 王峰；

【导师】 金景福； 何明友；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2004， 博士

【摘要】 本文以野外地质研究及室内测试数据为依据，研究了白秧坪银多金属矿床的区域地质构造背景、矿床产出的地质环境、同位素地球化学、稀土元素地球化学、微量元素地球化学、包裹体矿物学、流体地球化学、成矿地球化学过程等方面，研究结果表明： ①白秧坪银多金属矿床位于地质构造十分复杂的三江地区北段兰坪盆地的北端，区域复杂的构造演化为矿床的形成提供了有利的地质条件。矿床产在白垩系、侏罗系的次级断裂破碎带内。 ②同位素证据表明，成矿物质来自深部，具壳幔混合特征。含矿流体介质水以大气降水为补给的地下水。 ③微量元素证据表明，白秧坪银多金属矿床与金满铜矿床及喜山期富碱岩体具有相似的元素组合。 ④稀土元素配分模式为近于平坦型或者为中稀土富集型，富集中稀土的样品与盆地内啦井温泉区的泉华、加拿大不伦瑞克块状硫化物喷流型矿床中的矿石所具有的稀土配分特征类似。 ⑤含矿流体的化学性质为酸性，属Na⁺—Cl^-型水溶液。 ⑥成矿元素的助溶剂主要为CO₂，其配合物主要为氯配合物，这些助溶剂和配离子均来自壳幔深部。 ⑦含矿流体中成矿元素主要以CuCl⁺、CuCl₂^-、AgCl⁰、AgCl₂^-等形式迁移。 ⑧成矿过程是一个温度、压力不断降低的过程，随着温度、压力的降低，pH值增加，Eh、f_O2、f_S2不断降低。更多还原

【Abstract】 Based on geologic investigation in the field and a lot of analysis data in the laboratory, this paper has studied the regional geology and structure background of Baiyangping silver and polymetallic deposit, and also studied ore deposit geology, isotopic geochemistry, rare earth element geochemistry, trace elememnt geochemistry, inclusion, solution geochemistry, process of the ore-forming geochemicstry, etc.. The result is that:(1) Baiyangping silver and polymetallic deposit located the northern of Lanping Basin. The complicated regional geology and structure evolvement offer advantageous geological condition for ore-foming.(2) The source of ore-forming material was came from depth, had the crust-mandle mixed characteristic. The water of solution was groundwater supplied by atmosphere precipitation.(3) The Baiyangping deposit, the Jinman copper deposit and Himalayan alkali rich intrusive bodies have the similar elements combination.(4) The REE patterns of vein minerals show an enrichment of middle REE.(5) The chemical quality of solution was acidity, belong to Na+-Cl- solution.(6) Auxiliary agent of ore-forming elements was mainly CO2, and mineralizing agent was Cl-, and all of them were came from the crust-mantle.(7) The ore-forming elements in the solution was transported by CuCl0, CuCl2, AgCl0, AgCl2- and so on.(8) The process of ore-forming was a process of temperature and pressure falling. The T, P was lower, Eh, fO2,fS2 was lower too, pH was rise.更多还原