云南老王寨金矿的深部地质过程——来自显微岩相学和元素地球化学的证据  

Deep Geological Processes on Laowangzhai Gold Deposit in Yunnan: Evidence from Petrography and Element Geochemistry

作　　者：刘显凡[1,2] 楚亚婷[1] 卢秋霞[1] 赵甫峰[1] 李春辉[1] 肖继雄[1] 董毅[1] 

机构地区：[1]成都理工大学地球科学学院,成都610059 [2]南京大学内生金属矿床成矿机制研究国家重点实验室,南京210093

出　　处：《吉林大学学报（地球科学版）》2012年第4期1026-1038,共13页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(40773031;40473027);高等学校博士学科点专项基金项目(20105122110010;20115122110005);南京大学内生金属矿床成矿机制研究国家重点实验室开放研究基金项目(14-08-3);成都理工大学矿物学岩石学矿床学国家重点(培育)学科建设项目(SZD0407)

摘　　要：通过老王寨金矿围岩、蚀变岩石、矿石的显微岩相学和元素地球化学的系统研究发现:伴随硅化、碳酸盐化等蚀变和硫化物矿化,岩(矿)石中发育沿粒间、裂隙或角闪石解理纹贯入或穿插的黑色不透明超显微隐晶,经电子探针、扫描电镜和能谱分析鉴定,该固体物质主要由超显微晶石英、硅酸盐、碳酸盐、硫化物以及呈熔离交生关系的金红石、白钨矿和镜铁矿(磁铁矿)组成;熔离交生结构与沉淀共晶结构共存的特有岩相学特征指示成矿流体具备由熔体性质向热液性质转化的特性。结合岩(矿)石稀土微量元素研究,认为这种在透射光显微镜下呈黑色不透明的超显微隐晶固体物质,是具熔浆流体特点和超临界流体性质的地幔流体引发交代蚀变的直接微观表现之一;在交代蚀变过程中其性质由熔浆向地壳热液过渡,同时与地壳物质发生混染而有利于成矿作用的进行。The analysis of the micro-petrography and element geochemistry, combined with electron microprobe and SEM, shows that the extremely fine, black opaque materials in the ores consist mostly of super-microcrystalline quartz, silicate, sulfide, carbonate and the liquation of rutile, scheelite and specularite （magnetite）. These materials are distributed in intergranular space, along the cracks in minerals or along amphibole cleavage. They are associated with silicification, carbonation and sulfidation in the wall rocks, mineralized rocks and gold ores in the Laowangzhai gold deposit. The special petrographical texture characters of thees black opaque matters as coexistence of liqutation andprecipitating cocrystallization reveal the transitional features of the mineralizing fluid between the magmatic melt and the hydrothermal fluid. Combined with REE composition of the host rocks and ores, we suggest that these super-microcrystalline solid, black opaque materials under the transmitted-light microscope are the direct microcosmic manifestations of metasomatism of mantle fluids which are thought to be of the characters of melts and supercritical fluids. During the metasomatic alteration, the mantle fluids were transformed into thermal fluids from magmatic melts. Their simultaneous contaminations by hybridization of mantle-derived and crust-derived materials in the deep geological processes were favorable for gold metallogenesis in the area.

关 键 词：显微岩相学 超显微隐晶固体 深部过程 地球化学 壳幔混染 老王寨金矿 

分 类 号：P618.51[天文地球—矿床学]