湖南金船塘锡铋矿床辉钼矿Re-Os同位素测年及其地质意义  

Re-Os dating of the molybdenite from the Jinchuantang tin-bismuth deposit in Hunan Province and its geological significance

作　　者：刘晓菲[1] 袁顺达[1,2] 吴胜华[1,2] 

机构地区：[1]地质过程与矿产资源国家重点实验室,中国地质大学地球科学与资源学院,北京100083 [2]中国地质科学院矿产资源研究所,国土资源部成矿作用与矿产资源评价重点实验室,北京100037

出　　处：《岩石学报》2012年第1期39-51,共13页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40930419、40903020、40434011);中国博士后科学基金(20080430457);中国地质大学地质过程与矿产资源重点实验室基金(GPMR200839);公益性行业基金(200911007-11)联合资助

摘　　要：湖南东坡矿田位于南岭成矿带的西段,构造位置上处于扬子板块与华夏板块的对接地带,矿田内以千里山岩体为中心,发育一系列与燕山期花岗质岩浆作用有关的超大型、大型和中型钨锡钼铋多金属矿床。金船塘锡铋矿床是东坡矿田内一个以锡铋为主的大型矽卡岩型多金属矿床。本文对该矿床的矽卡岩型矿石中的辉钼矿进行了Re-Os同位素测年。结果显示,辉钼矿Re-Os同位素模式年龄范围为157.2±2.8Ma至162.4±2.4Ma,加权平均值为159.8±2.9Ma,对应的Re-Os等时线年龄为158.8±6.6Ma;这些年龄数据与柿竹园矿床辉钼矿的Re-Os等时线年龄(151.0±3.5Ma)在误差范围内基本一致,亦与区内千里山岩体锆石U-Pb年龄(152±2Ma)接近,指示金船塘Sn-Bi矿床与区内花岗岩具有密切的时间和成因关系。结合区域上已有的研究成果,包括金船塘矿床在内的东坡矿田的成岩成矿作用主要集中在149～161Ma,与南岭地区大规模的钨锡多金属成矿作用时限(150～160Ma)一致;另外,区域上的研究表明,幔源物质广泛参与了湘南钨锡矿集区晚中生代的成岩成矿作用,指示该区中-晚侏罗世爆发式的成岩成矿作用可能是区域地壳拉张-岩石圈伸展减薄背景下,强烈的壳幔相互作用的结果。The Dongpo ore field is in the western part of the Nanling polymetallic metallogenic belt,which is located in the intersection between Yangtze block and Cathaysian block.There are a series of large-and medium-sized W-Sn-Mo-Bi polymetallic deposits distributed around the Qianlishan granite in the Dongpo ore field.The Jinchuantang deposit is a large-sized skarn-type tinbismuth deposit in the Dongpo ore field.Direct Re-Os dating on molybdenites collected from the skarn ore in the Jinchuantang deposit have been carried out,in order to further restrict the age of mineralization.The results show that Re-Os model ages range from 157.2 ±2.8Ma to 162.4±2.4Ma,with an average of 159.8±2.9Ma,and give an isochron age of 158.8±6.6Ma.Combined with the ReOs isochron age（151.0±3.5Ma）of Shizhuyuan deposit and zircon SHRIMP U-Pb ages（152±2Ma）of the Qianlishan granite,it is suggested that the mineralization of the Jinchuantang Sn-Bi deposit is temporally and genetically related to the granite in this area. Based on previous studies,petrologenesis and metallogenesis of the Dongpo ore field,including the Jinchuantang deposit,mainly occurred 149～161Ma,which is similar to the large-scale tungsten-tin polymetallic mineralization（150～160Ma）in the Nanling region.Coupled with previous studies in this region,it is suggested that mantle components were extensively involved in the petrologenic and metallogenic processes of the Mesozioc W-Sn polymetallic ore district,southern Hunan Province,indicating that the Middle-Late Jurassic explosive mineralization of this region is probably as results of crust-mantle interactions under a geodynamic setting of the lithospheric thinning and extension.

关 键 词：RE-OS同位素 辉钼矿 锡铋矿床 金船塘 湖南 

分 类 号：P618.63[天文地球—矿床学] P618.69[天文地球—地质学]