云南普朗斑岩铜矿蚀变带成矿流体特征及其成矿意义

云南普朗铜矿位于义敦—中甸岛弧带南缘,是近年来我国发现的一个大中型斑岩铜矿床。该矿床具有典型的斑岩铜矿蚀变分带,由中心向外依次为钾硅化带、绢英岩化带、青盘岩化带。对矿区不同蚀变带中的石英流体包裹体进行了岩相学观察、均一温度测量和激光拉曼探针成分分析。均一温度测量结果表明,从普朗斑岩铜矿床钾硅化带到绢英岩化带再到青盘岩化带,成矿流体的平均均一温度从274.4℃到236.4℃再到203.0℃,呈明显下降趋势,可能与天水参与成矿有关。同时,激光拉曼探针成分分析结果表明,普朗斑岩铜矿床矿化期间的成矿流体属于富硫富氯流体,这种温度较高且富硫富氯的成矿流体在钾硅化带和绢英岩化带发生矿化作用将导致成矿物质强烈富集成矿。

Characteristics of the Ore-forming Fluids in Alteration Zones of the Pulang Porphyry Cupper Deposit in Yunnan Province and Its Metallogenic Significance

The Pulang porphyry copper deposit occurs in the southern segment of the Indosinian Yidun-Zhongdian island-arc belt and is a large-sized copper deposit discovered in China in recent years.This deposit has a typical alteration zonation of porphyry copper deposit,varying from potash and silicic alteration in the inner through phyllic alteration in the middle to propylitic alteration in the outer.This paper presents new petrographic observations,homogeneous temperature measurements and laser Raman microprobe analyses of fluid inclusions in quartz grains from the three alteration zones of the deposit.It is shown that the average homogeneous temperature of ore-forming fluid decreases from 274.4 ℃ through 236.4 ℃ to 203.0 ℃ with outward variation of alteration zone and indicates an evident temperature decreasing trend,which may be resulted from partial participation of meteoric water in mineralization.The laser Raman microprobe analyzing data are consistent with existence of ore-forming fluid with high sulfur and chlorine during mineralization in the deposit,and support occurrence of intensive mineralization caused by this high temperature ore-forming fluid with high sulfur and chlorine in the potash and silicic and phyllic alteration zones.