新疆乌伦布拉克铜矿流体包裹体特征及含矿岩体年代学

乌伦布拉克铜矿位于新疆东准噶尔野马泉-琼河坝铜多金属成矿带中，其矿床成因和成矿时代存在较大争议，从流体包裹体和锆石U-Pb定年等方面做了研究探讨.矿床主要发育富液相包裹体，成矿流体为低温（136.9~224.5℃）、低盐度（1.7%~5.6% NaCl eqv.）、低密度（0.97~1.01 g/cm3）流体，估算的成矿压力为2.76×107~4.49×107 Pa，对应的成矿深度为1.04~1.95 km，属于浅成矿床.激光拉曼探针测试结果表明流体液相组分主要为水，气相组分除水蒸气外，还含有一定量CH₄、N₂和H₂.锆石U-Pb测年结果显示含矿石英闪长岩年龄为440.5±3.3 Ma，不含矿石英斑岩年龄为419.7±3.3 Ma，表明研究区至少经历了2期岩浆活动，成矿作用从早志留世就已开始.矿床由内向外发育典型的"斑岩型"蚀变分带（强硅化带-钾化带-绢英岩化带-青磐岩化带），表明乌伦布拉克铜矿为斑岩型铜矿，形成于志留纪古亚洲洋向南俯冲的岛弧环境.东准噶尔甚至新疆北部地区在志留纪处于岛弧环境，该时期的岩浆岩带是形成和寻找斑岩型铜矿的有利地区. 

Fluid Inclusions and Geochronology of Wulunbulake Copper Deposit in Xinjiang

Wulunbulake copper deposit is located at the north-western segment of the Yemaquan-Qiongheba Cu-polymetallic metallogenic belt, East Junggar, Xinjiang. However, its genetic type and mineralizing age has been debated. This study presents new results on fluid inclusions and zircon U-Pb dating to precisely constrain the type and time of mineralization. The dominant fluid inclusions in Wulunbulake copper deposit are liquid-rich type, with low homogenization temperature (136.9-224.5℃), low salinity (1.7%~5.6% NaCl eqv.) and low density (0.97-1.01 g/cm3), the mineralizing pressure is 2.76×107-4.49×107 Pa and the corresponding depth is 1.04-1.95 km. The laser Raman spectroscopy results indicate that the ore-forming fluids consist of H₂O, CH₄, N₂, H₂. Zircon U-Pb dating results show that the formation age of ore-bearing quartz diorite and quartz porphyry is 440.5±3.3 Ma, and 419.7±3.3 Ma, respectively, indicating that there had experienced two-stage magmatic activities from Early Silurian. From the interior to the outer part of the deposit, there exist typical alteration zonation characteristics of porphyry deposits (silica alternation-potassic alternation-phyllic alternation-propylitization), and the geochemical characteristics of ore-bearing indicate that they were most possibly formed in arc setting. Its genetic type should be typical porphyry copper deposit and related to the southward subduction of the Paleo-Asian oceanic crust in the Early Silurian period. The East Junggar even northern Xinjiang was in the island arc environment in the Silurian, and the magmatic zone is a potential area for formation and prospecting of porphyritic Cu deposit.