新疆准噶尔北缘玉勒肯哈腊苏铜(钼)矿成矿流体研究

Ore-forming Fluid of Yulekenhalasu Cu—Mo Deposit on the Northern Margin of Junggar Basin, Xinjiang

玉勒肯哈腊苏中型斑岩铜(钼)矿是新疆准噶尔北缘卡拉先格尔斑岩铜矿带上的一个重要矿床。主要赋存于闪长玢岩中,少量在北塔山组火山岩及似斑状石英二长岩中,矿化呈细脉状、细脉—浸染状和浸染状,围岩蚀变主要为钾化、硅化、绢云母化和青磐岩化。主成矿阶段石英中包裹体类型为纯气体包裹体、气体包裹体、液体包裹体、含液体CO2的三相包裹体和含CO2两相包裹体五种。主成矿阶段成矿温度主要集中于140～340℃,流体盐度在3.06%～14.97%之间,密度集中于0.61～1.01g/cm3。成矿流体的气体成分以H2O、CO2为主,其次为N2、CH4、C2H6;液相成分阳离子以Na+为主,其次为Ca2+、K+、Mg2+;阴离子以SO2-4为主,其次为Cl-和F-。单个石英包裹体拉曼谱测试表明,主成矿阶段石英中包裹体具有明显的CO2谱峰,此外还有H2O(-OH)峰,部分具有CH4峰和N2峰。主成矿阶段成矿流体为H2O—NaCl—CO2—CH4(N2)体系。主成矿阶段的流体具有深源特征,成矿作用与斑岩有关,发生在浅成氧化环境。碳酸盐阶段方解石中包裹体类型主要为液体包裹体,少量气体包裹体。碳酸盐阶段具中低温(161～298℃)、低盐度(4.65%～7.17%)和低密度(0.78～0.95g/cm3)的特征,反映流体主要来自大气降水。

Yulekenhalasu medium porphyry copper--molybdenum deposit, which mainly hosted by the dioritic porphyrite and slightly occurs in volcanic rocks and porphyraceous adamellite of the Beitashan Formation, is an important deposit in the Kalaxiangeer porphyry copper belt on the Northern edge of the Junggar Basin. Cu--Mo mineralization disseminated or as veinlet and the main type of rock alterations are potassic alteration, silicification, sericitization and propylitization. Inclusions in quartz of the main ineralizing stage have five types： pure vapor inclusions, gas inclusions, liquid inclusions, three-phase CO2-type inclusions and two-phase CO2-type inclusions. In the main ineralizing stage, the ore-forming temperature is mainly 140 -340℃and salinity ranges from 3.06% to 4.97% NaC1 equiv, the density ranges from0.61g/cm3 to 1.01g / cm3. The gases in fluid inclusions are chiefly composed of H20 and CO2, N2, CH4, C2H6 secondly. The cations in inclusions are dominanted by Na and Ca2＋ , K＋ ,Mg2＋ secondly, the anions are SO24- and C1- ,F-secondly. Laser Raman spectra of quartz inclusions indicates that gases in fluid inclusions are major of CO2 and H20（ - OH） , a few of CH4 and N2. The inclusions system of main ineralizing stage is H20--NaC1--CO2--CH4 （N2 ）with deep-sourced characteristics. These suggest that the copper deposits are related to the porphyry and occurred in epizonal oxidation environment. Inclusions in calcite of the carbonate stage are mainly liquid inclusions, and gas inclusions in the minority. The carbonate stage have low medium temperature（ from 161℃ to 298℃ ）, low salinity （from 4.65% to 7.17% ） and low density （0.78 - 0. 95g/cm3） , which reflect the ore-forming fluids are the meteoric water mainly.