新疆东准噶尔卡拉麦里造山型金成矿系统与区域构造演化

新疆东准噶尔卡拉麦里地区以金水泉、双泉、南明水、苏吉泉东等为代表的金矿床,构成了一套与晚古生代碰撞造山有关的金成矿系统。矿床夹持于区域性的卡拉麦里深大断裂和清水—苏吉泉大断裂之间,矿化受次级脆-韧性断层控制,以中等至陡倾斜的含金石英脉和破碎蚀变岩的形式产于晚古生代浅变质火山沉积岩中。流体包裹体、H-O-S-Pb同位素和热液锆石U-Pb年代学研究表明,成矿流体具中高温(集中于240~330 ℃)、低盐度(<6% NaCl_eq)、富CO₂的变质流体特征,成矿物质来自赋矿的火山沉积岩系,流体不混溶(相分离)和水-岩反应(围岩硫化作用)是导致金沉淀的主要机制,成矿深度变化于7~15 km之间,成矿时代约为314 Ma。晚石炭世至早二叠世,研究区的构造体制由挤压向走滑或走滑伸展转换,构造应力的释放导致深部变质脱水形成的低盐度CO₂-H₂O-NaCl±CH₄含金流体,沿走向NW至近EW向的走滑剪切断裂向地壳浅部流动,并在脆-韧性过渡带或脆性变形带的次级断裂中形成含金石英脉及蚀变岩型金矿石。

The orogenic Au mineralization system and regional tectonic evolution in the Kalamaili area,East Junggar,Xinjiang

Au deposits, including the Jinshuiquan, Shuangquan, Nanmingshui, and East Sujiquan Au deposits in the Kalamaili area of eastern Junggar, Xinjiang, constitute a mineralization system related to the late Paleozoic collisional orogeny. The deposits are sandwiched between the regional Kalamaili and Qingshui-Sujiquan faults. Au mineralization is controlled by the subsidiary brittle-ductile faults in slightly metamorphosed, late Paleozoic volcanic sedimentary rocks, and typically occurs as medium-to-steep dipping auriferous quartz veins and surrounding altered rocks. Fluid inclusions, H-O-S-Pb isotopes, and hydrothermal zircon U-Pb dating indicate that the ore-forming fluids are characterized by medium-to-high temperature (mostly 240-330 ℃), low salinity (<6 wt% NaCl_eq), and CO₂-rich metamorphic water. The ore-forming material was sourced from host volcanic sedimentary rocks. Fluid immiscibility (phase separation) and fluid-rock interaction (wall-rock sulfidation) are the principal mechanisms of Au deposition. The timing of mineralization was approximately 314 Ma, and mineralization depths ranged from 7 to 15 km. From the Late Carboniferous to Early Permian, the transition of the tectonic system from compression to strike-slip or strike-slip extension in the study area resulted in the migration of deep metamorphic auriferous CO₂-H₂O-NaCl±CH₄ fluids to shallower depths along NW- to EW-trending strike-slip faults. Au precipitation in the subsidiary faults of the brittle-ductile transition zone or brittle deformation zone led to the formation of auriferous quartz veins and related altered rock ores.