阿尔泰可可托海3号脉花岗伟晶岩侵位机制、熔-流体演化、稀有金属富集机理及待解之谜  

The emplacement mechanism,melt-fluid evolution,rare-element metallogenesisand puzzles of the Koktokay No.3 pegmatite rare elemental deposit,Altai

作　　者：秦克章[1,2] 周起凤 唐冬梅[1] 王春龙 朱丽群[1,2] QIN Kezhang;ZHOU Qifeng;TANG Dongmei;WANG Chunlong;ZHU Liqun(Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Institute of Mineral Resources Research,China Metallurgical Geology Bureau,Beijing 101300,China;Faculty of Earth Resources,China University of Geosciences,Wuhan,Hubei 430074,China)

机构地区：[1]中国科学院矿产资源研究重点实验室,中国科学院地质与地球物理研究所,北京100029 [2]中国科学院大学地球与行星科学学院,北京100049 [3]中国冶金地质总局矿产资源研究院,北京101300 [4]中国地质大学资源学院,湖北武汉430074

出　　处：《地质学报》2021年第10期3039-3053,共15页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41602095);中国科学院重点部署项目(编号ZDRW-ZS-2020-4-1);国家“十二五”科技支撑计划新疆305项目(编号2011BAB06B03-04)联合资助的成果。

摘　　要：新疆阿尔泰可可托海3号脉以独特的实心礼帽形态、完美的同心环状结构分带和复杂的稀有金属矿化组合闻名于世,是我国最重要的稀有金属矿床之一。可可托海3号脉伟晶岩岩浆具有不均一性和高度演化特征。伟晶岩岩浆沿缓倾斜节理上侵,在周缘断裂的帮助下通过岩浆顶蚀形成实心礼帽形态。岩浆就位后经历了岩浆阶段、岩浆-热液阶段和热液阶段,分别伴随Be-Nb-Ta、Li-Be-Nb-Ta和Ta-Cs-Rb-Hf矿化。结晶分异作用和液相不混溶控制着3号脉的稀有金属富集和沉淀序列,流体交代可影响稀有金属再分配。外部带(Ⅰ~Ⅳ带)的强烈结晶分异过程和发生于Ⅳ带与Ⅴ带间的流体大规模出溶,有利于岩浆达到锂饱和浓度,开始锂的大规模沉淀。指出熔-流体演化过程的精细刻画、稀有金属成矿机理的进一步解析、岩浆成因的深入探讨、挥发分P、F、B、Li和CO_(2)对稀有金属成矿的影响以及缓倾斜帽沿深部找矿为未来研究方向。The Koktokay No.3 pegmatite dyke is famous for its overall shape of a hat,concentric zonation pattern,and complex rare-elemental mineralization assemblages.The magma of the Koktokay No.3 pegmatite is heterogeneous and highly evolved.The main emplacement mechanism for the No.3 pegmatite dyke involves upward intrusion of the pegmatite magma along gently inclined joints and stay in place in the form of a solid hat with the help of periperal faults.After emplacement,the pegmatite magma experienced three stages of melt,melt-fluid and late hydrothermal accompanied by mineralization of Be-Nb-Ta,Li-Be-Nb-Ta and Ta-Cs-Rb-Hf,respectively.Fractional crystallization and liquid immiscibility control the enrichment and deposition sequence of rare elements in the Koktokay No.3 pegmatite and hydrothermal replacement may have played a role on redistribution of the rare elements.The strong fractional crystallization of the outer zones(Ⅰ~Ⅳ)and large fluid exsolution between zonesⅣandⅤare favorable for the magma to achieve lithium saturation concentration and the system to begin lithium deposition.An important future research focus should be on the detailed description of melt-fluid evolution process,further analysis of metallogenetic mechanism of the rare elements,a thorough discussion on the genesis of magma,influence of P,F,B,Li and CO_(2) on rare metal mineralization,and deep prospecting along the gently inclined brim.

关 键 词：花岗伟晶岩 侵位机制 结晶分异 液相不混溶 稀有金属富集 新疆可可托海 

分 类 号：P618.6[天文地球—矿床学] P588.131[天文地球—地质学]