新疆哈腊苏铜矿床Ⅰ号矿化带流体包裹体和碳氢氧同位素地球化学

青河县哈腊苏铜矿床Ⅰ号矿化带位于准噶尔北缘卡拉先格尔斑岩铜矿带,铜矿化主要呈不均匀团块、细脉或细脉浸染状产于花岗闪长斑岩、石英闪长斑岩及玄武岩、辉斑玄武岩围岩中。矿石中石英和方解石流体包裹体划分为H_2O-NaCl型和H_2O-CO_2(±CH_4/N_2)-NaCl型。成矿温度主要集中在120～431℃,峰值在390、290和190℃。成矿流体盐度(w(NaCl_(eqv)))变化于0.53%～66.76%,峰值在19.5%、12.5%、9.5%和1.5%。密度为0.55～1.11 g/cm~3。矿脉中石英和方解石的δ~(18)O_(SMOW)值为2.9‰～12.3‰,δ~(18)O_(H_2O)值为—5.81‰～4.83‰,δD_(SMOW)为-129‰～-80‰,表明成矿流体主要为岩浆水和混合大气降水。方解石的δ~(13)C_(PDB)变化于-2.4‰～-1.4‰,δ~(18)O_(SMOW)为8.3‰～9.2‰,表明流体中的碳来自岩浆。对辉钼矿石英脉中辉钼矿进行了Re-Os同位素测年,获得等时线年龄为(378.3±5.6)Ma,与花岗闪长斑岩锆石SHRIMP U-Pb年龄(381～375 Ma)在误差范围内一致。早期成矿作用发生在中泥盆世,与斑岩有关,晚期叠加成矿作用发生在中、晚三叠世,与构造-岩浆-热液活动有关。

The fluid inclusions and C, H and O isotopic geochemistry of the Mineralized Zone No.1 at the Halasu copper deposit, Xinjiang

The Mineralized Zone No.I at the Halasu copper deposit in Qinghe County is situated in Kalaxiange'er porphyry copper belt. The copper-bearing minerals mainly occur in the form of heterogeneous gobbets, veinlets and veinlet-disseminated in the granodiorite porphyry, quartz diorite porphyry, basalt and pyroxene phenocrysts basalt. Two types of fluid inclusions, namely H_2O-NaCl and H_2O-CO_2 (±CH_4/N_2)-NaCl types, have been recognized in quartz and calcite from the ore. Homogenization temperatures of fluid inclusions vary from 120 to 431 ℃, with three temperature peaks at 390,290 and 190 ℃. Salinity ranges from 0.53% to 66.76 % NaCl_(eqv), with four peaks at 19.5% NaCl_(eqv), 12.5% NaCl_(eqv), 9.5% NaCl_(eqv) and 1.5% NaCl_(eqv). Ore fluid densities range from 0.55 to 1.11 g/cm~3. The δ~(18)O_(SMOW) values of quartz and calcite in the ore vein range from 2.9‰ to 12.3‰ with corresponding δ~(18)Ofluid values of -5.81‰ to 4.83‰ and δD values of fluid inclusions between -129‰ and -80‰. The isotopic data imply that the ore-forming fluids of the Halasu copper deposit were mainly derived from magmatic fluids, with some contributions from meteoric water. The δ~(13)C_(PDB) values of calcite define a narrow range of -2.4‰ to -1.4‰ and δ~(18)O_(SMOW) values range from 8.3‰ to 9.2‰ indicating that the carbon in the ore fluids was mainly derived from magma. Re-Os dating was performed on molybdenite from molybdenite vein, which yielded isochron ages of (378.3±5.6) Ma. This isochron age is coincident with the age of 381 - 375 Ma from granodiorite porphyry pluton within error range. Early mineralization formed in the Middle Devonian, which was closely related to porphyry systems. The Late-Middle tectonic-magmatic-hydrothermal-mineralization overlapped the early porphyry mineralization in the Halasu copper deposit.