新疆准噶尔北缘玉勒肯哈腊苏斑岩铜矿床年代学研究

摘要

玉勒肯哈腊苏铜矿是近几年准噶尔北缘卡拉先格尔斑岩铜矿带发现的又一个中型斑岩铜矿,其成岩成矿年代学的研究可以对矿床模型构建、区域成矿规律的总结提供制约.矿区侵入岩发育,矿化主要受闪长玢岩控制,少部分赋存在似斑状黑云母石英二长岩和北塔山组火山岩、火山碎屑岩中.本文利用锆石LA-ICP-MS U-Pb法和辉钼矿Re-Os法对矿区岩体和矿化进行了成岩成矿年代学研究.结合前人的研究,认为矿区存在5次主要岩浆侵入事件:382Ma石英闪长岩侵入,379Ma形成含矿闪长玢岩,375～374Ma形成似斑状黑云石英二长岩,348Ma形成黑云母石英斑岩脉,266Ma形成二长斑岩,前三次岩浆侵入活动对应构造环境为板块俯冲阶段,后二次岩浆侵入活动为后碰撞阶段.9件辉钼矿样品Re-Os同位素等时线年龄为373.9±2.2Ma,表明铜钼成矿时代为中泥盆世晚期,与闪长玢岩侵入有关.%Yulekenhalasu copper deposit is a medium-sized porphyry deposit found in recent years in Kalaxiange'er porphyry capper metaliogenic belt in northlem Junggar area. Study on its geochronology will help further set up raetallogenic model and summarize regional ore-forming pattern. Mang intrusive rocks are exposed in the ore district. The Cu mineralized mainly occurs in the diorite porphyry with subordinate porphyroid biotite quartz monzonite and volcanic rocks and volcaniclastic rocks of Beitashan Formation. This paper studies geochronology of intrusive racks and minerah'zation using zircon LA-ICP-MS U-Pb and molybdenite Rc-Os method. Based on our and other people data .magma intrusion events in the Yulekenhalasu ore district can be divided into five stages: Quartz diorite invading at 382Ma,ore-bearing diorite porphyry forming at 379Ma,porphyroid biotite quartz monzonite forming at 375 to 374Ma,biotite quartz porphyry invading at 348Ma, and quartz monzonite porphyry forming at 266Ma. Three stages before are formed during the subduction of plate,and other stages corresponds to a period of postcollision during Late Paleozoic. Seven samples of molybaenite Re-Os isochron age is 373.9 ±2. 2Ma,suggesting the Cu-Mo mineralization occurred in the Late Middle Devonian,and relating to the diorite porphyry.