云南祥云金厂箐金(铜)矿床的成矿流体特征及流体来源

CHARACTERISTICS OF ORE-FORMING FLUIDS AND THEIR ORIGIN IN JINCHANGQING GOLD(COPPER) ORE DEPOSITS IN XIANGYUN,YUNNAN

金厂箐金(铜)矿床原生流体包裹体和流体氢氧同位素的研究成果表明该矿床改造期早阶段流体为中温、中等盐度,形成于酸性和相对较还原环境的硫酸盐型热卤水。晚阶段流体为低温、低盐和相较于早阶段形成压力更低和更氧化环境的氯化物型热卤水。成矿流体水来源于(晚阶段)或主要来源于(早阶段)雨水源地下水,其同成矿时的原始雨水(δ18O=-15.3‰)相比,氧同位素组成要重12‰～17‰,是在水岩比(W/R)较小的条件下与围岩水岩反应进行同位素交换的产物。

Based on the study of primary fluid inclusions, hydrogen and oxygen isotopes,it was considered that the early stage ore-forming fluid from Jinchangqing gold(copper) ore deposits was sulfate hot brine characteristic of intermediate temperature and salinity originated from the late stage ore-forming fluid under acidic and more reductive environment. However, the late stage ore-forming fluid was a sort of low temparature and salinity chloride hot brine originated from a lower pressure, acidic and more oxidative environment.The ore fluids were from(the late stage) or mainly from(the early stage) meteoric ground water which had a heavier oxygen isotope composition(12‰~17‰) than the original rain water(δ^(18)O= -15.3‰) formed during the gold mineralization.It was resulted from the exchange of oxygen isotopes during the reaction between ore-forming fluid water and wallrock under a lower water/rock ratio.