福建省紫金山高硫型Cu-Au矿床表生氧化带金矿体中主要载金矿物褐铁矿研究  

Study on Limonite of the Main Gold-bearing Minerals in the Supergene Oxidized Gold Ore Body of Zijinshan High-sulfidation(HS)Epithermal Cu-Au deposit, Fujian Province

作　　者：陈明勇 王虎 雷嫦 汪莹 CHEN Ming-Yong;WANG Hu;LEI Chang;WANG Ying(111 Geological Party,Guizhou Bureau of Geology Mineral Exploration and Development,Guiyang 550081,Guizhou,China;China Guizhou Geological Engineering Survey and Design Institute Co.,Ltd,Guiyang 550081,Guizhou,China)

机构地区：[1]贵州省地质矿产勘查开发局111地质大队,贵州贵阳550081 [2]贵州地质工程勘察设计研究院有限公司,贵州贵阳550081

出　　处：《贵州地质》2022年第4期322-331,385,共11页Guizhou Geology

基　　金：国家自然科学基金(41773048);国家重点研发计划(2016YFC0600207);中国科学院战略性先导科技专项(B类)(XDB18000000)联合资助。

摘　　要：福建省紫金山Cu-Au矿床是我国典型的高硫型浅成低温热液矿床,具有“上金下铜”的矿化分带。金矿主要产于潜水面以上的氧化带中,而铜矿则主要分布于潜水面以下的原生带中。前人对矿床岩石学、地球化学、矿物学和成矿时代等进行了大量深入研究,积累了丰富的研究成果,但对表生氧化带金矿体内的载金矿物-褐铁矿研究较少。本文通过手标本、矿相显微镜、场发射扫描电镜和电子探针对该褐铁矿进行系统的研究。研究结果表明褐铁矿的产出具有多期次和多结构类型的特点,其矿物成分以针铁矿为主,并含有少量的赤铁矿、绢云母和石英。不同结构类型褐铁矿主要成分(Fe_(2)O_(3))的差异是由于内部含水矿物发生不同程度的氧化脱水导致的,微量成分(SO_(3)、SiO_(2)、Al_(2)O_(3))不同则主要受环境的控制。淋滤过程中形成的Fe(OH)_(3)凝胶,对同时期释放出来的Au的吸附和聚集,并在随后过程中一起沉淀,这为后期形成大储量的金矿床和矿石选采工艺起到关键作用。对紫金山Cu-Au矿床表生氧化带金矿体内褐铁矿的研究,有助于加深对金矿床中自然金富集规律的认识,同时对整个矿床演化体系的理解也具有指导意义。Zijinshan Cu-Au deposit is one of the typical high sulfidation epithermal deposits in Fujian province, SE China.The gold and copper ore bodies show a distinct mineralization zoning of ‘gold up and copper down’:gold mineralization in the upper(shallower)mine levels in the oxidation zone above the modern water table, and copper at deeper levels in the primary zone below the modern water table.The former researches have carried out on the petrology, geochemistry, mineralogy and ore-forming ages, however, there are few researches on the limonite which is gold-bearing mineral in the supergene oxidation zone.In this paper, the limonite in gold ore body was studied by Field Emission Scanning Electron Microscope(FE-SEM)and Electron Probe Microanalysis(EPMA).It shows that the production of limonite was characterized by multiple stages and structural types.Limonite mainly consists of goethite and contains a small amount of hematite, muscovite and quartz.The different content of main ingredient(Fe_(2)O_(3))in different structural types of limonite are caused by different degrees of oxidation and dehydration of water-bearing minerals, the different content of trace ingredient(SO_(3),SiO_(2) and Al_(2)O_(3))is controlled by the forming environment.The Fe(OH)_(3) gel formed during the drum filtering process can adsorb and gather the natural gold that was released at the same time, and precipitates together in the subsequent process.This process plays a key role in applying the application of ore-selected mining processes and forming a large reserves.The study of limonite in the supergene oxidation zone gold ore body of Zijinshan Cu-Au deposit is helpful to deepen the understanding of the enrichment of natural gold rules in the supergene oxidation zone, and also has guiding significance for the understanding of the whole evolution system of the deposit.

关 键 词：紫金山 表生氧化带金矿体 褐铁矿 载金矿物 特征 

分 类 号：P618.41[天文地球—矿床学] P618.51[天文地球—地质学] P578.497