老寨湾金矿热液独居石地球化学特征及地质意义  

Geochemical Characteristics and Geological Significance of Hydrothermal Monazite in Laozhaiwan Gold Deposit

作　　者：李治平 皮桥辉[1] LI Zhiping;PI Qiaohui(Earth Sciences College of Guilin University of Technology,Guangxi Guilin 541004,China)

机构地区：[1]桂林理工大学地球科学学院,广西桂林541004

出　　处：《山东国土资源》2021年第5期17-25,共9页Shandong Land and Resources

基　　金：国家自然科学基金:运用独居石和磷钇矿U-Pb法精确测定卡林型金矿成矿年龄(项目编号:41674075)。

摘　　要：老寨湾金矿是“滇黔桂金三角”规模较大的微细粒金矿之一,前人对该矿床的研究已十分详尽,但多集中于地质特征和成因方面,对矿石在热液蚀变过程中元素地球化学特征研究甚少。由于后期次生氧化作用会导致独居石的原生结构被破坏,因此对其成因颇有争议。本文通过对老寨湾金矿区的独居石进行电子探针测试,分析独居石的内部结构、矿物组合以及稀土元素地球化学特征。结果表明,在先前存在的富钍独居石边部有新生的贫钍独居石,其地球化学特征与母体完全不同,通过对比分析边部独居石的微量元素地球化学特征,认为其成因应为热液交代,是岩浆期后载金热液流体交代地层碎屑富钍独居石并伴随金的沉淀过程而形成。结合本区地质特征,认为老寨湾金矿的形成很可能与岩浆热液作用有关。Laozhaiwan gold deposit is one of the fine-grained gold deposits with large scale in"Dian-Qian-Gui Golden Triangle Area".Many geological work have been carried out in this deposit in detail,but mostly focus on geological characteristics and the origin.Little research has been carried out on geochemical characteristics of the elements in the process of transformation.Since the secondary oxidation in the later stage will destroy the primary structure of monazite,the formation is quite controversial.In this paper,through the electron probe test of monazite in Laozhaiwan gold mining area,the internal structure,mineral composition and rare earth element geochemical characteristics of monazite have been analyzed.As showed by the results,there is a new thorium-poor monazite at the edge of the pre-existing thorium-rich monazite,and its geochemical characteristics are completely different from the parent body.Through a comparative analysis of the trace element geochemical characteristics of the edge monazite,it is believed that its origin should be heat liquid metasomatism.It was formed by the metasomatism of gold bearing hydrothermal fluid after magmatic stage and accompanied by the precipitation of gold,and accompanied by gold precipitation.Based on geological characteristics of this area,it is believed that the formation of Laozhaiwan gold deposit is probably related to magmatism.

关 键 词：老寨湾金矿 独居石成因 地球化学特征 

分 类 号：P595[天文地球—地球化学] P572[天文地球—地质学]