东昆仑五龙沟金成矿系统:基本特征、成矿控制与勘查标志

The Wulonggou gold system in East Kunlun Orogen:Geological characteristics,metallogenic controls and prospecting criteria

五龙沟金矿田位于东昆仑造山带东段,金成矿与三叠纪岩浆作用、脆性和/或韧性变形显示密切时空联系。但是,金容矿地质体类型与控矿构造特征尚不清,金成矿受哪些关键要素控矿尚不明确。本文通过广泛深入的文献资料调研与详细的野外调查,详细阐明了五龙沟地区金矿床地质特征与成矿地质环境,系统梳理、总结与对比了不同地段金矿床的矿化类型、容矿地质体与控矿构造。研究表明,五龙沟金矿田发育微细脉型、蚀变岩型、石英脉型等3种矿化类型,容矿地质体主要以元古界—奥陶系变质岩系与侵入岩类为主。早期韧性剪切作用导致矿源层中金的活化与预富集,金矿化主要受控于晚期北西向脆性变形及相关断裂破碎带。大规模金成矿与古特提斯洋关闭及伴随的同/后碰撞构造过程有关。北西向构造—蚀变带、侵入岩类与古老变质基底是五龙沟金矿田的重要勘查标志。

The Wulonggou gold field is located in the eastern segment of the East Kunlun Orogen.The gold metallogeny has close spatial and temporal relationships with Triassic magmatism and brittle and/or ductile deformation.However,the ore-hosting rocks and ore-controlling structures are still unclear,and the key controlling factors for the gold mineralization also remain obscure.In this paper,we conduct extensive and comprehensive literature research and detailed field investigation on the Wulonggou gold field.Based on this,we systematically clarified the characteristics and metallogenic setting of the deposit geology,and summarized and compared the mineralization styles,the ore-hosting rocks,and the ore-controlling structures.The gold mineralization in the Wulonggou gold field can be divided into three types,including the filling-vein,altered-rock,and quartz-vein types.The ore-hosting rocks can be classified into two groups:Proterozoic to Ordovician metamorphic rocks and the intrusive rocks.The early stage of ductile shearing contributes to the reactivation and pre-enrichment of gold,and the mineralization is suggested to be predominantly controlled by the NW-striking brittle deformation and associated fault–fracture zone.The large-scale gold metallogeny can be related to the closure of the Paleo-Tethys Ocean and subsequent syn-/post-collisional event.The NW-striking tectonic–alteration zones,intrusive rocks and ancient metamorphic basement are proposed as the important prospecting criteria for the Wulonggou gold field.