西昆仑木吉地区卡拉瓦拉伟晶岩型锂铍矿电气石地球化学特征及其成因探讨  

Geochemical characteristics and genesis of tourmaline in the Kalawala pegmatite-type lithium-beryllium deposit in the Muji region of West Kunlun.

作　　者：龙雨兵 王核[1,2,3] 张晓宇 黄亮 孙志强[1,2,3] 张嵩 董瑞[4] 王振宏 LONG YuBing;WANG He;ZHANG XiaoYu;HUANG Liang;SUN ZhiQiang;ZHANG Song;DONG Rui;WANG ZhenHong(Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;Key Laboratory of Mineralogy and Metallogeny,Chinese Academy of Sciences,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100049,China;School of Earth Science and Engineering,Hebei University of Engineering,Handan 056000,China)

机构地区：[1]中国科学院广州地球化学研究所,广州510640 [2]中国科学院矿物学与成矿学重点实验室,广州510640 [3]中国科学院大学,北京100049 [4]河北工程大学地球科学与工程学院,邯郸056000

出　　处：《岩石学报》2025年第3期905-921,共17页Acta Petrologica Sinica

基　　金：第二次青藏高原综合科学考察项目(2019QZKK0802);中国科学院先导战略性先导专项(XDA0430102);第三次新疆综合科学考察(2022xjkk1302)联合资助.

摘　　要：木吉地区的卡拉瓦拉锂铍矿床位于西昆仑-松潘-甘孜稀有金属伟晶岩成矿带的西段,其稀有金属伟晶岩成矿与三叠纪高分异花岗岩密切相关。电气石作为广泛分布于卡拉瓦拉各类伟晶岩中的重要矿物,是研究岩浆和热液系统的理想材料。通过对电气石主量和微量元素数据的详细分析,可以揭示其成因机制并追踪其地球化学演化过程。本文对卡拉瓦拉矿床中贫矿伟晶岩(BK)与含矿伟晶岩(MK)中的两类典型电气石样品进行了电子探针和激光剥蚀电感耦合等离子体质谱分析,发现卡拉瓦拉的电气石可分为碱性系列和X位空位系列,主要由铁电气石和锂电气石组成。BK型电气石主要分布于贫锂的花岗岩及其伟晶岩和细晶岩中,而MK型电气石则全部分布于富锂的花岗伟晶岩和细晶岩中。从BK型到MK型电气石的化学成分变化趋势显示,Fe和Mg含量逐渐减少,而Li、Al和F含量逐渐增加,表明复杂的元素交换过程导致了电气石成分的多样性。此外,电气石中大部分微量元素的含量变化幅度较大,平均含量范围为0.1×10^(-6)~10×10^(-6),其中Sr、Pb和Sn的富集指示电气石受到了热液流体的显著影响。而BK型和MK型电气石中主量元素和微量元素相关性的不一致,则进一步表明存在局部熔体/流体作用的可能性。The Kalawala lithium-beryllium deposit in the Muji region is situated in the western section of the West Kunlun-Songpan-Ganze rare metal pegmatite metallogenic belt,where rare metal pegmatite mineralization is closely associated with Triassic highly fractionated granites.Tourmaline,a widely distributed and significant mineral in various pegmatites of Kalawala,serves as an ideal material for studying magmatic and hydrothermal systems.Detailed analysis of major and trace element data of tourmaline can elucidate its genesis mechanism and trace its geochemical evolution.This study conducted electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry on two typical tourmaline samples from barren pegmatite(BK)and mineralized pegmatite(MK)in the Kalawala deposit.It was found that the tourmaline in Kalawala can be classified into the alkali series and the X-site vacancy series,primarily consisting of schorl and elbaite.BK-type tourmaline is mainly distributed in Li-poor granitoids and their associated pegmatites and aplite fields,whereas MK-type tourmaline is exclusively distributed in granitoid pegmatites and aplite field.The geochemical composition trends from BK-type to MK-type tourmalines show decreasing Fe and Mg contents,and increasing Li,Al and F contents,indicating a complex element exchange process that leads to tourmaline compositional diversity.Furthermore,the content of most trace elements in tourmaline varies significantly,with an average range of 0.1×10^(-6)~10×10^(-6).The enrichment of Sr,Pb and Sn suggests a significant influence of hydrothermal fluids on tourmaline.The inconsistency of major and trace element correlations between BK-type and MK-type tourmaline further indicates the possibility of local melt/fluid interactions.

关 键 词：电气石 稀有金属伟晶岩 西昆仑 岩浆-热液演化 

分 类 号：P578.953[天文地球—矿物学] P588.131[天文地球—地质学] P618.7