湘南九嶷山大坳钨锡矿的Re-Os同位素定年研究

Re-Os isotope dating of the Da'ao tungsten-tin deposit in the Jiuyi Mountains,southern Hunan Province

湘南九嶷山大坳钨锡矿床与具有铝质A型花岗岩特征的金鸡岭复式花岗岩关系密切。矿床类型包括云英岩体型、破碎带蚀变岩型、变花岗岩型和云英岩-石英脉型等4类。通过对云英岩-石英脉型钨锡矿中辉钼矿Re-Os同位素测年,获得辉钼矿的等时线年龄为(151.3±2.4)Ma,与花岗岩成岩年龄(151～156Ma)一致,显示成矿与成岩是同时的。通过对区域上获得的高精度成矿年龄综合分析对比,认为150～160Ma为南岭地区中生代大规模成矿作用的高峰期,九嶷山大坳钨锡矿床正是这一高峰期的产物。这为进一步研究区域成矿规律,指导区域找矿提供了重要同位素年代学依据。

The Da＇ao tungsten-tin deposit in the Jiuyi Mountains, southern Hunan, is closely related to the Jinjiling composite granite which has the characteristics of aluminous A-type granite. The deposit types include the greisen type, altered granite type, fractured zone alteration type and greisen-quartz vein type. Based on the precise Re-Os dating of molybdenite from the ore-bearing greisen-quartz vein, a mineralization age of 151.3± 2.4 Ma was obtained, which is consistent with the formation age （151-156 Ma） of granite, suggesting that the mineralization occurred simultaneously with the rock formation. An integrated analysis and comparison of highly precise mineralization ages obtained on a regional scale shows that the period of 150-160 Ma was the peak stage of Mesozoic large-scale mineralization in the Nanling region and that the Da＇ao tungsten-tin deposit in the Jiuyi Mountains is just the product of this peak stage. The new data provide important isotope chronological evidence for the further study of the regional lnetallogenic characteristics and guidance of regional mineral prospecting.