东天山哈密地区赤湖钼铜矿区斜长花岗斑岩锆石SHRIMP U-Pb年龄

Zircon SHRIMP U-Pb dating of plagiogranite porphyry in the Chihu molybdenum-copper district, Hami, East Tianshan

东天山赤湖斑岩钼铜矿床的形成时代和成矿地质背景至今尚存在争议,前人根据同一成矿带中土屋-延东斑岩铜矿的同位素地质年龄信息,认为赤湖钼矿的形成时代为中-晚泥盆世,系塔里木板块北部活动陆缘泥盆纪岛弧火山-深成作用的产物:近期一些研究者根据赤湖斑岩钼铜矿区斜长花岗斑岩锆石U-Pb和谐曲线年龄,认为矿化斜长花岗斑岩的侵位时代为晚石炭世,成矿作用与哈萨克斯坦-准噶尔板块南部活动陆缘晚石炭世汇聚阶段钙碱性岩浆侵入作用有关。在前人研究基础上,笔者对赤湖斑岩钼铜矿区矿化斜长花岗班岩体进行了锆石SHRIMP U-Pb定年研究,获得322Ma±10Ma(95％可信度)的年龄值, 表明赤湖斑岩铜矿床的形成时代为晚石炭世,成矿作用与晚石炭世钙碱性岩浆浅成侵位有关。

The age and geological setting of the Chihu molybdenum-copper deposit in the East Tianshan orogenic belt are still in dispute. According to the isotopic age data of the Tuwu-Yandong porphyry copper deposit in the same metallogenetic belt, the predecessors considered that the Chihu molybdenum-copper deposit formed during the Mid-Late Devonian and should be the product of Devonian island-arc volcanism and plutonism on the northern active continental margin of the Tarim plate. However, according to the zircon U-Pb concordia age of plagiogranite porphyry in the Chihu porphyry molybdenumcopper district, recently some researchers believe that the mineralized plagiogranite porphyry was emplaced during the Late Carboniferous and that the mineralization is related to calc-alkaline magmatic intrusion in the Late Carboniferous convergence stage on the southern active margin of the Kazakhstan-Junggar phte. SHRIMP U-Pb dating was carried out on zircons from mineralized plagiogranite porphyry in the Chihu molybdenum-copper district in this research on the basis of previous research. It yielded an age of 322±10 Ma （95% level of confidence）, which suggests that the Chihu molybdenum-copper deposit formed during the Late Carboniferous and that the mineralization is related to Late Carboniferous hypabyssal intrusion of calcalkaline magma.