黑龙江宝山夕卡岩型铜钼钨多金属矿床成岩成矿时代及其地质意义

Diagenetic and Metallogenic Ages of Baoshan Cu-Mo-W Deposit in Heilongjiang Province,China and Its Geologic Significance

宝山铜钼钨多金属矿床为小兴安岭—张广才岭成矿带上的一个典型夕卡岩型矿床,赋存于花岗闪长岩-正长花岗岩体与下寒武统铅山组富镁质碳酸盐岩的接触部位。本文通过锆石LA-ICP-MS U-Pb同位素定年,获得赋矿花岗闪长岩的成岩年龄为(248.4±2.1)Ma,表明其侵位时代为早三叠世。对矿石中的辉钼矿进行了Re-Os同位素分析,获得等时线年龄为(242.0±1.0)Ma,加权平均年龄为(241.9±1.7)Ma。成矿、成岩作用发生于早—中三叠世,与古亚洲洋闭合时间吻合,发生于大陆碰撞环境中。

Baoshan Cu-Mo-W deposit is a typical skarn deposit located in the northern section of the Xiaoxing＇anling-Zhangguangcailing metallogenic belt. It occurs at the contact zone between granitoid rocks and carbonate rocks of the Cambrian Qianshan Formation. In this paper, we present new data about zircon U-Pb age of ore-hosting granodiorite and molybdenite Re-Os age. The LA-ICP-MS U-Pb zircon analyses yield a concordia age of （248.4± 2.1 ） Ma for granodiorite, indicating that the granodiorite was intruded in the Early Triassic. The Re-Os isochron age of molybdenlte is （242. 0±1. 0） Ma with a weighted average of （241.9±1.7） Ma, which is slightly younger than the emplacing age of granodiorite. Intrusion of the granodiorite and associated Cu-Mo-W mineralization occurred in a collisional tectonic setting during the Early-Middle Triassic, which is related to the closure of the Paleo-Asian Ocean.