吉尔吉斯斯坦安达什(Andash)金铜矿床地质特征及成矿构造背景分析

Geological characteristics and metallogenic tectonic setting of Andash gold-copper deposit in Kyrgyzstan

安达什(Andash)金铜矿床位于吉尔吉斯斯坦西北部的塔尔迪布拉克—安达什—阿克塔什金铜矿集区,是吉尔吉斯斯坦北天山造山带重要的斑岩型金铜矿床之一。矿床金铜矿化主要呈细脉浸染状发育于花岗闪长岩中,矿体受近东西向和北西向断裂控制。矿床发育钾化、绢英岩化和青磐岩化等斑岩型矿床的特征围岩蚀变,其中金铜矿化与绢英岩化关系最为密切。花岗闪长岩LA-ICP-MS锆石U-Pb测年获得的加权平均年龄为(469.6±3.0)Ma,形成于中奥陶世。结合岩石地球化学特征和区域构造背景分析,认为花岗闪长岩为岛弧岩浆活动的产物,安达什金铜矿床形成于Terskey洋演化末期成熟岛弧环境中。大型构造带的可对接性及相似的构造背景表明中国新疆那拉提山北缘缝合带两侧具有寻找斑岩型铜金矿床的潜力。

The Andash gold-copper deposit is located in the northwestern Kyrgyz and belongs to the Taldybulak-Andash-Aktash gold-copper ore field.It is one of the most important porphyry gold-copper deposits in the North Tianshan orogen of Kyrgyzstan.The gold-copper mineralization is characterised by vein-disseminated sulfides in granodiorite and the ore bodies are controlled by nearly EW and NW fractures.The wall rock alterations of porphyry deposits such as potassium,silicification,sericitization and propylitization are well-developed in the mining area,while the gold-copper mineralization is genetically related to the sericitization.The granodiorite LAICP-MS zircon U-Pb dating yields a weighted mean age of(469.6±3.0)Ma,indicating that it was formed in the middle Ordovician.Therefore we proposed that the granodiorite originated from island arc magmatism and the Andash gold-copper deposit was formed in the mature island arc environment at the end of the Terskey evolution of Ocean.The dovetailability of large tectonic zones and similar tectonic setting suggest that both sides of the suture zone of the northern edge of Nalati Mountain have the potential to find porphyry Au-Cu deposits.