闽西南中甲锡多金属矿床的Re-Os同位素年龄及其地质意义

Re-Os AGES OF THE ZHONGJIA TIN POLYMETALLIC DEPOSIT,SOUTHWESTERN FUJIAN, AND THEIR GEOLOGICAL SIGNIFICANCE

矿床成矿时代是矿床成因研究的重要任务之一,长期以来只能通过间接方法确定。Re Os同位素测年方法是直接精确测定辉钼矿及相关矿化模式年龄的有效手段。本文使用碱熔法和ICPMS技术对中甲锡多金属矿床辉钼矿Re Os同位素年龄进行测定,结果表明,中甲锡多金属矿床矿化模式年龄为193～196Ma,属燕山早期早阶段成矿,和成矿有关的黑云母花岗岩则形成于晚印支期—早燕山期。东南大陆在晚印支期开始了从特提斯构造域向环太平洋构造域的转换。燕山早期成矿的确定为区域上寻找新的成矿远景区提供了直接的年代学证据。

The mineralization age of ore deposits is one of the imp ortant subjects in the study of the genesis of ore deposits and it has long been obtained by means of indirect methods.The Re-Os dating technique is an effecti ve means for the direct accurate determination of the model ages of molybdenite and related mineralization.The alkali fusion combined with ICPMS was used in thi s study to determine the Re-Os ages of molybdenite in the Zhongjia tin poly metallic deposit.The results indicate that the model age of mineralization of th e Zhongjia tin polymetallic deposit is 193-196 Ma,assigned to the early stage o f the early Yanshanian period.The biotite granite related to mineralization was e mplaced during the late Indosinian-early Yanshanian The transformation from the T ethys tectonic domain to the circum-Pacific tectonic domain in the continent of southeastern China began in the late Indosinian.The tin polymetallic mineraliza tion resulted from the transformation of the two tectonic domains.The determinat ion of the early Yanshanian mineralization provides direct chronological evidenc e for looking for new regional ore prospect areas.