藏北温泉-河流-盐湖耦合成矿系统锂的地球化学行为与迁移过程  

Geochemical behavior and migration processes of lithium in the coupled geothermal spring-river-salt lake mineralization system in northern Xizang

作　　者：薛飞[1,2] 谭红兵 张西营[2] 陈国辉[1] 葛璐 李超[1] 苗卫良 XUE Fei;TAN HongBing;ZHANG XiYing;CHEN GuoHui;GE Lu;LI Chao;MIAO WeiLiang(School of Earth Sciences and Engineering,Hehai University,Nanjing 211100,China;Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lakes,Qinghai Institute of Salt Lakes,Chinese Academy of Sciences,Xining)

机构地区：[1]河海大学地球科学与工程学院,南京211100 [2]中国科学院青海盐湖研究所,青海省盐湖地质与环境重点实验室,西宁810008

出　　处：《岩石学报》2025年第3期968-982,共15页Acta Petrologica Sinica

基　　金：第二次青藏高原综合科学考察研究(2022QZKK0202);国家自然科学基金项目(U22A20573);中央高校基本科研业务费专项资金(B230201014);青海省盐湖地质与环境重点实验室开放基金(2024-KFKT-A07)联合资助.

摘　　要：青藏高原是我国最重要的锂(Li)资源基地,广泛分布着特色盐湖卤水锂矿和富锂地热泉,两者存在密切的物源联系,共同构成了温泉-河流-盐湖外生锂耦合成矿系统。然而,对于锂在该系统内部运移过程中的地球化学行为仍缺乏详细刻画。本研究系统采集了夏康坚温泉、索美藏布河和拉果错的水样,分析了样品的水化学组成、微量元素组成及Li同位素组成。结果表明,索美藏布上游河水中的溶解态锂主要源自硅酸盐的风化,表现出低锂(7.84μg/L)和高δ^(7)Li值(+8.21‰)的特征。在经过富锂(8071.73μg/L)且低δ^(7)Li值(+0.19‰)的夏康坚温泉排泄补给后,索美藏布河水发生了锂的显著富集和锂同位素的负漂移,锂元素富集了200多倍,达到1777.02μg/L,δ^(7)Li值降低了8.07‰,降至+0.14‰。经过温泉区后,河水中的锂浓度在流动过程中大体保持稳定(1105.49~1452.33μg/L),δ^(7)Li值仅提高0.6‰(+0.12~+0.72‰),这表明硅酸盐风化和次生矿物吸附对富锂河水地球化学成分影响有限,充足的锂能够通过河流稳定地补给到盐湖中,表现出与低锂背景河流不同的演化特征。夏康坚温泉-索美藏布-拉果错盐湖共同组成了一个从地史时期持续到现在的耦合成矿系统。富锂温泉作为主要的内生物源,河流作为矿质表生输送路径,尾闾湖泊作为容矿场所,高寒干旱气候条件导致的蒸发浓缩作为成矿驱动力,持续形成盐湖卤水锂矿。锂元素完成了从源到汇、从深部到浅部的运移富集,实现了从内生成矿到外生成矿的形式转换,成为锂循环的重要一环。The Qinghai-Tibet Plateau is China s most significant lithium(Li)resource base,characterized by extensive distributions of Li-rich salt lakes and Li-enriched geothermal springs.These two sources are closely linked,forming a coupled exogenous Li mineralization system involving hot springs,rivers and salt lakes.However,the geochemical behavior of lithium during its migration within this system remains inadequately detailed.This study systematically collected water samples from the Xiakangjian hot spring,the Suomei Zangbo river and the Laguo Co salt lake,and analyzed their hydrochemical,trace elemental and Li isotopic compositions.The results show that the dissolved Li in the upper reaches of the Suomei Zangbo primarily originates from silicate weathering,characterized by low Li concentration(7.84μg/L)and highδ^(7)Li values(+8.21‰).Following the discharge from Xiakangjian spring with high Li concentrations(8071.73μg/L)and lowδ^(7)Li(+0.19‰),the river exhibits an extraordinary Li enrichment and a negative shift in Li isotopes,with Li concentration increasing by over 200 times reaching 1777.02μg/L,andδ^(7)Li values decreasing by 8.07‰to 0.14‰.After passing through the hot spring area,the river s Li concentration stabilizes(1105.49~1452.33μg/L)with a slight increase in Li isotopes(0.12‰~0.72‰),indicating limited influence from silicate weathering and secondary mineral adsorption on the geochemistry of the Li-rich river water.Consequently,sufficient Li can be stably supplied to the salt lakes via the river,displaying evolutionary characteristics distinct from those of low-Li rivers.The Xiakangjian geothermal spring,Suomei Zangbo and Laguo Co together constitute a continuously operating coupled mineralization system from geological history to the present.The Li-rich hot springs act as the primary endogenous source,the river as the transport pathway,and the terminal lake as the deposition site,with evaporation and concentration driven by the cold,arid climate facilitating the ongoing formation of Li bri

关 键 词：锂同位素 水化学 成矿系统 温泉-河流-盐湖 青藏高原 

分 类 号：P592[天文地球—地球化学] P595[天文地球—地质学]