摘要
马海盆地位于柴达木盆地北部,卤水资源丰富,但关于晶间卤水的系统研究仍相对薄弱,缺乏深入的水文地球化学分析。文章以马海盆地晶间卤水为研究对象,结合水化学特征与δD、δ^(18)O、δ^(34)S和δ^(7)Li等同位素组成,探讨其水文地球化学特征及成因,并构建晶间卤水成因模式。研究表明,马海盆地晶间卤水pH为7.67~8.07,TDS为315.30~335.00 g/L,属高矿化度、弱碱性的Cl-SO_(4)型晶间卤水。水化学分析表明,晶间卤水的溶质主要源于石盐、钾盐和石膏等矿物的溶解,水化学演化过程受蒸发浓缩、水-岩作用及阳离子交换作用的控制,储层封闭性较差,变质程度较低。氢、氧同位素值分别为-38.60‰~-22.80‰和-1.30‰~3.20‰,表明晶间卤水起源于大气降水或冰雪融水,并经历了显著的蒸发浓缩和水岩作用。硫同位素值为9.50‰~11.80‰,进一步反映出储层封闭性较差,且可能存在深部流体的混合补给。锂同位素值为30.49‰~32.74‰,进一步揭示晶间卤水主要受冲积扇地下水(55.56%~73.71%)和Ca-Cl泉水(26.29%~44.44%)的混合补给。综合分析认为,马海盆地晶间卤水的形成受大气降水的入渗补给、石盐及钾盐的溶滤、深部流体的混合及蒸发浓缩等水文地球化学过程共同作用,最终形成其现今的地球化学特征。该研究成果对于深化马海盆地卤水成因研究、提升资源评价水平及促进可持续开发具有重要意义。
The Mahai Basin,situated in the northern Qaidam Basin,hosts abundant brine resources.How‐ever,systematic investigations of intercrystalline brines in the region remain limited,particularly regarding their hydrogeochemical evolution and genesis.This study focuses on the intercrystalline brines of the Mahai Basin,integrating major ion chemistry with stable isotopes(δD,δ^(18)O,δ^(34)S,andδ^(7)Li)to characterize their hydrogeochemical signatures and elucidate their genetic mechanisms.A conceptual genetic model is subse‐quently proposed.The intercrystalline brine exhibits high salinity(TDS=315.30~335.00 g/L)and weak alkalinity(pH=7.67~8.07),and is classified as Cl-SO_(4)-type brine.Geochemical analyses suggest that sol‐utes are predominantly derived from the dissolution of halite,potash salts,and gypsum.Brine evolution is governed by evaporation,water-rock interactions,and cation exchange,while relatively poor reservoir sealing and weak diagenesis are also indicated.TheδD(-38.60‰to-22.80‰)andδ18O values(-1.30‰to 3.20‰)indicate meteoric or glacial meltwater origin,subsequently modified by significant evaporation and water-rock interaction.Theδ^(34)S values(9.50‰to 11.80‰)imply limited reservoir confinement and potential contributions from deep-sourced fluids.Theδ^(7)Li values(30.49‰to 32.74‰)further reveal that the brine is predominantly recharged through mixing of groundwater of alluvial fan(55.56%-73.71%)and Ca-Cl-type spring water(26.29%-44.44%).Collectively,these findings demonstrate that the formation of intercrystalline brine in the Mahai Basin is driven by a combination of meteoric water infiltration,mineral dissolution,deep fluid mixing,and evaporative concentration.This study enhances the current understand‐ing of brine genesis in arid continental basins and provides a theoretical framework for resource assessment and the sustainable development of saline groundwater systems.
作者
冯宁
秦西伟
马玉亮
张帆
刘瑞博
蒋子文
刘成林
丁兆鹏
FENG Ning;QIN Xiwei;MAYuliang;ZHANG Fan;LIU Ruibo;JIANG Ziwen;LIU Chenglin;DING Zhaopeng(School of Geological Engineering,Qinghai University,Xining,810016,China;Key Laboratory of Cenozoic Resource&Environment in North Margin of the Tibetan Plateau,Xining,810016,China;SDI Xinjiang Lop Nur Potash Salt Co.,LTD.,Hami,839000,China;Institute of Advanced Studies,China University of Geosciences,Wuhan,430074,China;The Fourth Geological Exploration Institute of Qinghai Province,Xining,810001,China;Qinghai Key Laboratory of Shale Gas Resources,Xining,810001,China;School of Earth Resources,China University of Geosciences,Wuhan,430074,China)
出处
《盐湖研究》
2025年第6期29-38,共10页
Journal of Salt Lake Research
基金
青海省盐湖地质与环境重点实验室开放基金项目(2024-KFKT-B07)
青海大学部省合建盐湖化工大型系列研究设施自主课题(2024-DXSSZZ-01)
青海大学大学生科研训练计划项目(SRT202526)
青海省地质矿产勘查开发局地质勘查项目(2023-03-18,63000000024T000002987)。
关键词
晶间卤水
地球化学特征
稳定同位素
成因
马海盆地
Intercrystalline brine
Geochemical characteristics
Stable isotopes
Genesis
The Mahai Basin 38
