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麦卡因大型VMS型Au-Ag-Cu-Zn-Pb矿床位于中哈萨克斯坦西北部的Baidaulet-Akbastau地区。地质剖面测量和岩石薄片研究表明,麦卡因矿区发育中基性火山岩(玄武岩和安山岩)和次火山岩(辉绿-辉长岩和辉绿岩),矿化主要与安山岩有关。对矿区火山岩地球化学分析表明,矿区岩石分为两种类型:类型Ⅰ为拉斑-钙碱性系列中基性火山岩(玄武岩和安山岩)和次火山岩(辉绿-辉长岩和辉绿岩),岩石具平坦的稀土配分模式,亏损Nb和富集Th/Yb,显示俯冲特点;类型Ⅱ为钙碱性系列安山岩,具典型的右倾型稀土配分模式,亏损Nb和富集Th/Yb,指示其形成于岛弧环境。含矿岩石为类型Ⅱ安山岩。对类型Ⅱ安山岩进行了锆石Lu-Hf同位素和SIMS U-Pb年龄分析,结果表明,锆石εHf(t)为较高的正值(+4.28~+14.84),指示其是地幔物质部分熔融的产物,锆石SIMS U-Pb年龄为459.1±4.8Ma,指示其成岩年龄属于晚奥陶世。因此,哈萨克斯坦麦卡因大型VMS型矿床含矿火山岩为钙碱性系列安山岩,形成于晚奥陶世岛弧环境。对比研究认为,哈萨克斯坦早古生代波谢库尔-成吉思斑岩型-VMS型成矿带向东延伸到我国西准噶尔沙尔布提山,沙尔布提山具有形成VMS型矿床的岩浆条件和构造环境。
The large-scale CMS-type Au-Ag-Cu-Zn-Pb deposit is located in the Baidaulet-Akbastau region in the northwestern part of Kazakhstan. Geological profiling and thinning of rock show that the basic mica rocks (basalts and andesites) and sub-volcanic rocks (diabase-gabbro and diabase) develop in the McCain mine and are mainly related to andesite. Geochemical analysis of volcanic rocks in the mining area shows that there are two types of rock in the ore district: Type I is basaltic volcanic rocks (basalts and andesite) and subvolcanic rocks (diabase-gabbro and diabase) , The rocks have a flat REE pattern, depleted in Nb and enriched in Th / Yb, showing subduction characteristics. Type II is a series of calc-alkaline andesite with typical right-inclined REE patterns, depleted Nb and enriched Th / Yb, indicating It is formed in an island arc environment. The ore-bearing rocks are type Ⅱ andesite. The zircon-Lufnium isotopic dating and the SIMS U-Pb dating of type II andesite show that εHf (t) is a high positive value (+4.28 ~ +14.84) indicating that it is a partial melting of the mantle material The zircon SIMS U-Pb age is 459.1 ± 4.8Ma, indicating that the diagenetic age belongs to Late Ordovician. Therefore, the large-scale coal-bearing type VMS deposits in the McCoy, Kazakhstan, are calc-alkaline andesite formed in the arc environment of the late Ordovician island. The comparative study shows that the Early Paleozoic Bostikar-Chenggisi porphyry-VMS metallogenic belt in Kazakhstan extends eastward to the Shalbuti Mountain in west Juggar, China. The Shalbuti Mountain has the magmatic conditions for forming the VMS deposit And the construction environment.