西昆仑大同地区加里东期成岩、成矿事件:来自LA-ICP-MS锆石U-Pb定年和辉钼矿Re-Os定年的证据

摘要

Datong district in the western Kunlun have discovered a series of related with intrusive rocks the Cu-Mo occurrences and mineralized spots. Busilajin Cu-Mo occurrence is the new found magmatic hydrothermal vein-type Cu-Mo deposit in Datong district With LA-ICP-MS zircon U-Pb dating to ore-bearing biotitic adamellite and graniteaplite in Busilajin, diagenetic ages are 446Ma and 449Ma respectively. Using molybdenite Re-Os dating in it, metallogenic age is 435 ±25Ma. It was shown that metallogenesis is later than diagenesis. The Busilajin Cu-Mo deposit is a product from structural and magmatic activities in Middle Caledonian, whose metallogenic material came from mixture of crust and mantle. Metallogenesis is related with complex evolution of paleo-Asia structural domain and Tethys structural domain. This large scale mineralization in Middle Caledonian may derive from strong magmatic activities and metallogenesis under local extended settings after accretionary orogenesis and crust thichening in the western Kunlun.%大同地区相继发现了一系列与侵入岩有关的铜钼矿点和矿化点,布斯拉津铜钼矿化点是在大同地区新发现的岩浆热液脉状铜钼矿化点.首次采用LA-ICP-MS锆石U-Pb测年技术对大同地区布斯拉津含矿黑云母石英二长岩和花岗细晶岩进行锆石U-Pb同位素测年,获得成岩年龄分别为446Ma和449Ma；对辉钼矿中Re-Os同位素进行测试,获得等时线年龄为435±25Ma,表明大同地区成矿作用略晚于成岩作用,岩浆热液铜钼矿化是加里东中期的构造、岩浆活动的产物,成矿物质来源以壳幔混源为主,成矿作用与古亚洲构造域和特提斯构造域的复合演化有关.发生于加里东中期的这一成矿事件,是在俯冲挤压背景下的间歇拉张作用影响下的强烈岩浆活动和成矿作用的产物.