喜马拉雅成矿带祥林大型锡铍钨矿床铍赋存状态及其富集机制  

The occurrence status and enrichment mechanism of beryllium in the Xianglin large tin-beryllium-tungsten deposit in the Himalayan metallogenic belt

作　　者：王艺云 李光明 张志 张林奎 马国桃 石洪召 黄春梅 黄勇[2] WANG YiYun;LI GuangMing;ZHANG Zhi;ZHANG LinKui;MA GuoTao;SHI HongZhao;HUANG ChunMei;HUANG Yong(Chengdu Center,China Geological Survey(Geosciences Innovation Center of Southwest China),Chengdu 610299,China;Research Center of applied Geology,China Geological Survey,Chengdu 610036,China)

机构地区：[1]中国地质调查局成都地质调查中心(西南地质科技创新中心),成都610299 [2]中国地质调查局军民融合地质调查中心,成都610036

出　　处：《岩石学报》2025年第5期1547-1570,共24页Acta Petrologica Sinica

基　　金：国家重点研发计划项目(2023YFC2906805、2021YFC2901903);国家科技重大专项(2024ZD1003205);国家自然科学基金项目(91955208、42002097、42202061);地质调查项目(DD202402028、DD202402069)联合资助详细信息。

摘　　要：铍是典型的双性元素,其富集成矿方式复杂多样。喜马拉雅成矿带错那洞穹隆近年来发现了具有超大型资源前景的铍锡钨多金属矿,但关于该区铍从岩浆阶段到岩浆-热液过渡阶段再到热液阶段的富集成矿作用过程及其控制因素尚不明确。本文以错那洞穹窿北侧的祥林大型锡铍钨矿床为研究对象,运用光学显微镜、电子探针(EPMA)、激光剥蚀等离子质谱仪(LA-ICP-MS)及原位微区XRD等手段,系统研究了铍的赋存状态及其富集机制。研究表明,祥林矿床铍主要以绿柱石形式赋存于伟晶岩型和锡石硫化物脉型矿体中,在矽卡岩型矿体中则主要以类质同象形式赋存于符山石、方柱石等矽卡岩矿物中,仅有极少量硅铍石、羟硅铍石和锂白榍石等独立铍矿物产出。伟晶岩型绿柱石(Brl-I)属Li-Cs绿柱石,呈均一结构;热液脉型绿柱石(Brl-II)属Na绿柱石,发育环带结构,成分复杂,反映了明显的热液叠加改造作用。两期绿柱石均为t型,其c/a值从伟晶岩期到热液脉期呈递减趋势(1.0011→1.0007),指示Li+置换Be^(2+)程度增强。元素置换机制从单一的八面体(NaFe^(2+)□^(-1) Al^(-1))置换通道演变为复杂的四面体((Na,Cs)Li□^(-1) Be^(-1))和八面体((Na,Cs)(Fe^(2+),Mg)□^(-1) Al^(-1))置换通道。铍的富集成矿经历了从岩浆期到热液期的多阶段演化,具体过程为:(1)岩浆分异期,导致Be在残余熔体中富集;(2)伟晶岩期,流体出溶和过冷却作用促使Brl-I结晶;(3)矽卡岩期,Be主要通过[BeO_(4)]^(6-)置换铝硅酸盐矿物中的[AlO_(4)]^(5-);(4)热液脉期,Be以氟络合物形式(BeF_(4)^(2-)、BeF_(3)^(-)等)迁移,在碱交代作用和水岩反应过程中形成Brl-II。这些发现深化了对岩浆-热液型铍多金属矿床成矿理论的认识,为区域找矿勘查提供了重要参考。Beryllium is a typical amphoteric element,and its enrichment and mineralization processes are complex and diverse.The Cuonadong Dome in the Himalayan metallogenic belt has recently discovered a polymetallic beryllium-tin-tungsten deposit with promising large-scale resource potential.However,the processes and controlling factors of beryllium enrichment and mineralization,ranging from the magmatic stage to the magmatic-hydrothermal transition stage and further into the hydrothermal stage,are not yet fully understood.This study focuses on the Xianglin large tin-beryllium-tungsten deposit located on the northern side of the Cuonadong Dome.Utilizing optical microscopy,electron probe microanalysis(EPMA),and laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS),we systematically investigated the occurrence and enrichment mechanisms of the beryllium.The results reveal that beryllium in the Xianglin deposit primarily occurs as beryl in the pegmatitic and cassiterite-sulfide vein-type ore bodies.In the skarn-type ore bodies,beryllium is mainly present as isomorphic substitution in skarn minerals such as wollastonite and andradite,with only small amounts of independent beryllium minerals such as phenakite,bertrandite and bityite.The pegmatitic beryl(Brl-I)is a Li-Cs beryl with a homogeneous structure,whereas the hydrothermal vein-type beryl(Brl-II)is a Na-rich beryl that develops zoned structures,with complex compositions indicating significant hydrothermal overprinting.Both types of beryl are t-type,with c/a values decreasing from the pegmatitic stage to the hydrothermal vein stage(1.0011→1.0007),suggesting enhanced Li+substitution for Be^(2+).The substitution mechanism evolved from simple channel-octahedral substitution(NaFe^(2+)□^(-1) Al-1)to more complex channel-tetrahedral substitution((Na,Cs)Li□^(-1) Be^(-1))and channel-octahedral substitution((Na,Cs)(Fe^(2+),Mg)□^(-1) Al-1).Beryllium enrichment and mineralization underwent multi-stage evolution from the magmatic to hydrothermal stages through

关 键 词：绿柱石 关键稀有金属 富集机制 错那洞穹窿 喜马拉雅成矿带 

分 类 号：P578.953[天文地球—矿物学] P618.72[天文地球—地质学]