The fluid inclusions and C,H and O isotopic geochemistry of the Mineralized Zone No.1 at the Halasu copper deposit,Xinjiang.
The fluid inclusions and C,H and O isotopic geochemistry of the Mineralized Zone No.1 at the Halasu copper deposit,Xinjiang.
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作者：
M. Key
青河县哈拉苏铜存款Ⅰ号矿化带位于卡拉仙格尔斑岩铜矿带内，含铜矿物主要以不均匀的团块、细脉、细脉状浸染状产出于花岗闪长斑岩、石英闪长斑岩、玄武岩和辉石斑晶玄武岩中，流体包裹体有H_2 O-NaCl和H_2 O-CO_2两种类型，包裹体中的含铜矿物主要以水、水、水包裹体均一化温度为120 ~ 431℃，在390、290和190℃有三个温度峰，盐度为0.53%~ 66.76%NaCl_（eqv），包裹体的盐度为0.53%~ 66.76%NaCl_（eqv），包裹体的盐度为0.53%~ 66.76%NaCl_（eqv）。在19.5%NaCl_（eqv）、12.5%NaCl_（eqv）、9.5%NaCl_（eqv）和1.5%Na-Cl_（eqv）处有四个峰。矿石流体密度为0.55 ~ 1.11 g/cm~ 3，石英和方解石的δ~（18）O_（smow）值为2.9‰ ~ 12.3‰，相应的δ~（18）O_（fluid）值为-5.81 ‰ ~ 4.83‰，流体包裹体的δD值为-129 ‰ ~-80 ‰。哈拉苏铜存款的成矿流体主要来自岩浆流体，方解石的δ~（13）C_（PDB）值在-2.4 ‰ ~-1.4 ‰之间，δ~（18）O_（smow）值在-1.4 ‰ ~-1.4 ‰之间。结果表明，成矿流体中的碳主要来源于岩浆，Re-Os同位素年龄为8.3‰ ~ 9.2‰。得出的等时线年龄（378.3±5.6）Ma，与381- 388 Ma的年龄一致。375 Ma，早期成矿作用形成于中泥盆世，晚中期构造-岩浆-热液-热液-岩浆成矿作用与哈拉苏铜存款矿床早期斑岩成矿作用重叠。
The Mineralized Zone No.Ⅰat 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%Na-Cl_(eqv). Ore fluid densities range from 0.55 to 1.11 g/cm~3.Theδ~(18)O_(smow)values of quartz and calcite in the ore vein range from 2.9‰to 12.3‰with correspondingδ~(18)O_(fluid)values of-5.81‰to 4.83‰andδD 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.Theδ~(13)C_(pdb)values of calcite define a narrow range of-2.4‰to-1.4‰andδ~(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.