新疆东准噶尔顿巴斯套金矿床含金黄铁矿Rb-Sr等时线年龄及地质意义

Rb-Sr Isochron Age of Auriferous Pyrites from Dunbasitao Gold Deposit in East Junggar,Xinjiang,and Its Geological Significance

新疆东准噶尔地区金矿床矿石矿物的直接定年研究比较缺乏.顿巴斯套金矿床位于该地区阿尔曼泰构造带东段北东侧,为该构造带中规模最大的金矿床.应用Rb-Sr同位素定年方法对该矿床9件黄铁矿样品进行了成矿时代测定,获得等时线年龄为268±3Ma(MSWD=0.7),该年龄与矿区西北部高钾钙碱性花岗岩成岩时代一致,成矿与中二叠世构造岩浆活动具有密切关系.同时结合近些年来金矿床成岩成矿年代学研究成果,认为中二叠世(270~260Ma)为东准噶尔地区一个重要的金成矿时限.黄铁矿Rb-Sr年龄的厘定,显示顿巴斯套金矿床为中二叠世东准噶尔地区后碰撞伸展背景下构造-岩浆-流体活动的产物,也为东准噶尔金矿床成矿作用对比和找矿实践提供了参考.

The study on direct dating of ore minerals in gold deposits in East Junggar is relatively scarce.The Dunbasitao gold deposit,located in the northeastern part of eastern Aermantai structural belt,is one of typical gold deposits in the region.RbSr isotopic dating of 9 pyrites separated from the Dunbasitao gold deposit yielded an isochron age of 268.3±2.8 Ma(MSWD=0.7),and this result is in good agreement with the high-potassium calc-alkaline granite in the northwestern part of ore district,indicating that gold mineralization was related to granite crystallization.Meanwhile,combining with the studies about metallogenic chronology of diagenetic and mineralization in East Junggar in recent years,it is suggested that Middle Permian from^270 Ma to 260 Ma may be an important time range of gold mineralization in East Junggar,Xinjiang.According to previous studies and the Rb-Sr ages reported,it is interpreted that the Dunbasitao gold deposit was formed in an post-collision extended environment related to lithospheric extension with tectonic,magma and fluid activities during the Middle Permian in East Junggar.The age of Dunbasitao gold deposit reported in this study is of great significance both for comparison studies in mineriza-tion of gold deposits in the region and practice for mineral exploration.