湘东锡田钨锡矿区成岩成矿时代研究

湘东锡田钨锡矿是近年来在找矿上有重大突破的地区。笔者在分析前人资料的基础上,应用Rb-Sr全岩法和Re-Os辉钼矿法对锡田花岗岩及产于其中的云英岩石英脉型钨锡矿进行了精确定年。结果表明:锡田岩体主体、补体和晚期花岗岩形成年龄分别为:165±16Ma(2σ)、151±24Ma(2σ)、114±14Ma(2σ);早期云英岩石英脉型钨锡矿辉钼矿Re-Os等时线年龄为150±2.7Ma。研究显示该区可能还残留有印支期花岗岩,钨锡成矿与燕山期花岗岩侵入活动有关。不同类型钨锡矿生成顺序为:矽卡岩型→早期云英岩石英脉型→晚期云英岩石英脉型→破碎带蚀变岩型。

METALLOGENIC AGES OF THE XITIAN TUNGSTEN-TIN DEPOSIT, EASTERN HUNAN PROVINCE

The Xitian region in eastern Hunan is one of the areas with significant breakthrough for the W-Sn prospecting in recent years.On the basis of the analysis to previous data,authors give accurate ages of the Xitian granite and related greisen-quartz vein type tungsten-tin ores by the whole rock Rb-Sr and Re-Os dating method.The results show that the ages for the main body,complement and the latest of the Xitian granite are,respectively,165±16 Ma(2σ),151±24Ma(2σ)and 114±14Ma(2σ).The Re-Os isochron of molybdenites from the early greisen-quartz vein type is 150±2.7 Ma.It is suggested that there might exist Indosinian granites in this area and the W-Sn mineralization are related to the Yanshanian granite.The order of formation for different type W-Sn ores is as follows:the skarn rock,early greisen-quartz vein,late greisen-quartz vein and fracture zone alteration types.