北祁连西段干巴河脑钼钨矿床辉钼矿Re-Os测年及C-H-O-S同位素特征

Molybdenite Re-Os Dating and C-H-O-S Isotopic Characteristics of the Ganbahenao Mo-W Deposit in Western Segment of North Qilian Mountains

干巴河脑钼钨矿是在北祁连山地区新近发现的中型石英脉型钼钨矿床。在研究矿床地质特征基础上,根据石英包裹体的C、H、O稳定同位素和辉钼矿Re、S含量的研究,认为成矿物质来自地壳,成矿流体以岩浆流体为主,成矿与S型花岗岩有关;通过辉钼矿的Re-Os同位素定年,获得等时线年龄(424±10)Ma,成矿时间与其围岩——金佛寺S型花岗岩的成岩时间相近。综合区域构造演化认为,矿床与晚志留世古北祁连海闭合后、陆陆碰撞过程形成的金佛寺S型花岗岩有着成因联系,金佛寺花岗岩体为成矿提供了成矿物质。

The Ganbahenao deposit in the north Qilian Mountains is a middle Mo-W deposit newly discovered in the western segment of north Qilian Mountains.It belongs to the quartz vein type.Both molybdenite and wolframite are dominant metal minerals in the ore. Through the study of the geological features of the deposit, the C,H, O isotopic compositions of fluid inclusions in quartz and the content of both Re and S in molybdenite, authors conclude that ore-forming materials were derived from the crust, the ore-forming fluid mainly came from the magmatic fluid. The Ganbahenao deposit was genetically related to the S-type granite. Re-Os dating of molybdenite yields model ages between （413.3±6.0）-（426.4±6.6） Ma and an isochrone age of （424±10） Ma, which is nearly equal to that of the wall rock, the Jinfosi S-type plutons.The Ganbahenao deposit and the Jinfosi plutons are formed in the environment of the continent-continent collision after the closure of the north Paleo-Qilian ocean in Late Silurian Period.The Jinfosi plutons offers the ore-forming sources and space.