新疆昭苏卡拉盖雷铜金矿床地质地球化学特征及成因探讨

Geological-Geochemical Characteristics and Genesis of Kalagailei Copper-Gold Deposit in Zhaosu County,Xinjiang

卡拉盖雷铜金矿床位于新疆西天山那拉提构造带境内西段,为近年在该成矿带内发现的首例以Cu为主,伴生Au、Co等的火山岩型热液矿床。δD、δ18O分析结果表明,成矿流体在早—中阶段以岩浆热液为主,晚阶段有大气降水加入。δ34S分析结果表明,硫源主要来自深部地壳或上地幔,并有地层硫混入。铅同位素分析表明,矿区铅源为壳、幔混合俯冲带铅。辉钼矿的Re-Os同位素模式年龄为(259.6±9.7)Ma,说明矿床早阶段的成矿年龄为早二叠世末期。笔者进一步探讨了矿床成因,认为大哈拉军山组火山岩为早期矿源层;在晚石炭世后碰撞伸展阶段,来自地壳深部的含矿岩浆热液沿区域深大断裂、火山通道及浅部断裂系统运移并萃取早期矿质元素,于有利构造部位形成矿体。

Kalagailei copper-gold deposit,located in the western Nalati tectonic belt of Western Tianshan Mountains,Xinjiang,is the first Cu-dominated volcanic hydrothermal deposit accompanied by Au and Co etc. in this metallogenic belt. The hydrogen and oxygen isotope compositions show that ore-forming fluids were mainly made up of magmatic water in the early period and added by rainwater in the later period. The characteristics of sulfur isotope show that the sulfur sources originate from the deeper crust and upper mantle,accompanying with the interfusion of strata sulfur. The lead isotope compositions indicate that lead sources are mixture of crust and mantle. The Re-Os isotopic model age of molybdenite is （259. 6 ± 9. 7） Ma,indicating that early stage mineralization age of the deposit falls into the mid-late Permian. The authors probe into the genesis and consider the volcanic rocks of Dahalajunshan Formation are the source beds. At the collision-extensional stage of late Carboniferous,mineral-enriched magmatic hydrothermal fluids originating from the deep crust migrate through regional and large faults,volcanic vents and shallow faults system,and extract early mineral elements,forming the orebody in the favorable tectonic positions.