北阿尔金余石山含金石英脉地质构造特征与流体作用  

Geological Structure Characteristics and Fluid Activity of the Gold-bearing Quartz Veins on the Yushishan Area,North Altyn Tagh

作　　者：李孝文 曹淑云 刘建华[1] 周丁奎 李文轩 蒋少涌[2] 曹汉琛 吴玉[3] LI Xiaowen;CAO Shuyun;LIU Jianhua;ZHOU Dingkui;LI Wenxuan;JIANG Shaoyong;CAO Hanchen;WU Yu(State Key Laboratory of Geological Processes and Mineral Resources,School of Earth Sciences,China University of Geosciences,Wuhan 430074,Hubei,China;State Key Laboratory of Geological Processes and Mineral Resources,School of Resources,China University of Geosciences,Wuhan 430074,Hubei,China;Beijing Research Institute of Uranium Geology,Beijing 100029,China)

机构地区：[1]中国地质大学(武汉)地质过程与矿产资源国家重点实验室和地球科学学院,湖北武汉430074 [2]中国地质大学(武汉)地质过程与矿产资源国家重点实验室和资源学院,湖北武汉430074 [3]核工业北京地质研究院,北京100029

出　　处：《大地构造与成矿学》2021年第6期1061-1093,共33页Geotectonica et Metallogenia

基　　金：国家重点研发计划(2017YFC0602401);优秀青年基金项目(41722207);国家自然科学基金面上项目(41472188,41430211,41802218)联合资助。

摘　　要：北阿尔金构造带东部余石山地区是近年来新发现的极具勘探潜力的稀有金属矿区,区域内出露有含金石英脉矿化体,矿化体的产出总体上受区域韧性剪切带和断层带共同控制。本文重点针对该矿化体,在宏观和显微构造特征观测的基础上,结合流体包裹体性质特征及流体来源进行了深入分析。研究表明,含金石英脉矿化体经历了从成岩‒成矿到被改造的演化过程,其在微观上保留有明显的原生和次生的结构特征。其中原生结构主要包括发育环带的石英及各类金属矿物,而次生结构则为叠加于原生结构之上的蚀变和构造变形特征。石英呈现出明显的韧‒脆性转换构造变形,晶体内发育不同类型的流体包裹体,指示着不同的流体演化环境。其中成矿期流体以富二氧化碳为主要特征,温压环境约为P=125~250 MPa,T=300~365℃,成矿深度约为9~12 km;而改造期流体以贫二氧化碳的水‒盐体系为主要特征,温压环境约为P<100 MPa,T=165~235℃,深度小于8.3 km。流体的不混溶作用在成岩成矿过程中扮演了重要角色,韧‒脆性构造转换所造成的流体压力降低是导致流体不混溶作用的关键因素。成矿流体主要以岩浆水为主,但受后期改造作用的影响而混入了大气降水。总体上含金石英脉矿化体产于韧‒脆性转换带并受剪切带及断裂带的控制,呈现出与剪切带型金矿基本一致的特征。The Yushishan area in the eastern of the North Altyn tectonic belt is a newly discovered rare metal ore belt with high exploration potential.The gold-bearing quartz veins exposed in this area are controlled by the regional ductile shear zone and brittle fault zone.The gold-bearing quartz veins were investigated through detailed macroscopic and microscopic structural observations,combined with the characteristics of fluid inclusions and fluid source analysis.The results show that the gold-bearing quartz veins have undergone an evolutionary process from diagenesis-mineralization to modification and alteration.Under the microscopy,the quartz veins show obvious primary and secondary structural features.The primary structure mainly includes quartz zoning mineral texture and various metallic minerals,while the secondary structure is the characteristics of alteration and structural deformation superimposed on the primary structure.The gold-bearing quartz veins exhibit significant ductile-brittle transition deformation,and different types of fluid inclusions are developed within the quartz crystals,indicating different fluid evolution environments and stages.The fluid in the ore-forming stage is mainly characterized by carbon dioxide-rich,the temperature and pressure environment of P=125‒250 MPa,T=300‒365℃,with a mineralization depth of about 9‒12 km.The fluids in the reformation stage are CO_(2)-poor water-salt system,with P<100 MPa,T=165‒235℃and the depth<8.3 km.The ore-forming fluid is mainly dominated by magma water,but it is mixed with atmospheric precipitation due to the later transformation.Fluid-immiscibility in the gold-bearing quartz veins plays an important role in the ore-forming processes.The depression caused by the ductile-brittle transition is the key factor leading to fluid immiscibility.On the whole,the gold-bearing quartz vein mineralized bodies are controlled by the shear zone and fault zone,showing characteristics basically consistent with that of shear zone type gold deposits.

关 键 词：含金石英脉 石英环带结构 流体包裹体 流体不混溶作用 氢氧同位素 

分 类 号：P542[天文地球—构造地质学]