青海柴北缘滩间山地区金龙沟金矿成矿模式总结与找矿前景分析

An Analysis of Metallogenic Model and Prospecting of Jinlonggou Gold Deposit in Tanjianshan Area,Northern Margin of Qaidam Basin,Qinghai Provice

金龙沟金矿是青海柴北缘成矿带发现的首个大型金矿床,在前人研究资料的基础上,通过分析金龙沟金矿地质背景、矿床特征、矿石质量、成矿期次及蚀变等成矿作用特征,认为金龙沟金矿为两期成矿作用形成的复合叠加浅成中温热液型金矿床,分别为晚志留世(425~400 Ma)变质变形成矿期和中泥盆世(374 Ma)岩浆热液成矿期,主成矿期次为中泥盆世岩浆热液成矿期,与该时代花岗闪长斑岩杂岩体的岩浆活动具有密切的成生关系,成矿构造环境分别为加里东晚期陆壳俯冲碰撞、华力西早期后造山陆内隆升环境;控矿构造样式组合为:北西向剪切带+近北东向皱褶+滑脱断裂裂隙。从控矿构造样式的空间展布特征分析认为金龙沟金矿深部和走向上找矿潜力较小,但其一级控矿构造(区域性北西向韧性剪切带)内叠加有次级皱褶和和断裂构造的区域是该区有利的金成矿部位并具有较好找矿前景。

Jinlonggou gold deposit is the first large-scale gold deposit discovered in the metallogenic belt of northern Qaidam Basin,Qinghai province.Based on the previous research data and the analysis of the geological background,deposit characteristics,ore quality,metallogenic stages and alteration,the authors considered that Jinlonggou gold deposit is a composite superimposed epithermal one formed in a two-stage mineralization:Late Silurian(425400 Ma)metamorphic metallogenic period and Middle Devonian(374 Ma)magmatic hydrothermal metallogenic period.The main metallogenic period is Middle Devonian magmatic hydrothermal metallogenic period,which is closely related to the magmatic activity of granodiorite porphyry complex in this era.The tectonic metallogenic environment is late Caledonian continental crust subduction and collision,and early Variscan post-orogenic intracontinental uplift.The pattern of ore-controlling structure is NW-trending shear zone+near NE-trending fold+detachment fracture.The spatial distribution of ore-controlling structure indicates that there is little prospecting potential in the deep part and in the strike of Jinlonggou gold mine.The areas with secondary folds and fracture structures superimposed in the first-class ore-controlling structure(regional NW-trending ductile shear zone)are favorable gold metallogenic location and prospecting.