新疆北部阿尔泰造山带扎格依库都克金矿床成因机制:来自流体包裹体和硫同位素的制约  

Genesis of the Zhageyikuduke Gold Deposit in the Altay Orogenic Belt,North Xinjiang:Constraints from Fluid Inclusions and S Isotopes

作　　者：刘莹廷 张雪冰 黄庆 吴世山 LIU Yingting;ZHANG Xuebing;HUANG Qing;WU Shishan(College of Geology and Mining Engineering,Xinjiang University,Urumqi 830017,Xinjiang,China;State Key Laboratory of Deep Earth Processes and Resources,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;Xinjiang Oyasa Mineral Exploration Co.,Ltd.,Urumqi 830011,Xinjiang,China)

机构地区：[1]新疆大学地质与矿业工程学院,新疆乌鲁木齐830017 [2]中国科学院广州地球化学研究所,深地过程与战略矿产资源全国重点实验室,广东广州510640 [3]新疆远山矿业勘查有限公司,新疆乌鲁木齐830011

出　　处：《大地构造与成矿学》2025年第2期351-366,共16页Geotectonica et Metallogenia

基　　金：新疆维吾尔自治区自然科学基金面上项目(2022D01C362)资助。

摘　　要：扎格依库都克金矿床位于新疆阿尔泰造山带南缘额尔齐斯成矿带东南部,其矿体形态与空间展布主要受控于矿区广泛发育的NE向断裂构造。与额尔齐斯成矿带其他金矿床相比,该矿床具有埋藏浅、品位高的特征,但其成矿机制尚未明确。本研究基于矿物组合特征与矿脉穿切关系,将扎格依库都克金矿床的热液成矿过程划分为三个阶段:成矿前黄铁矿‒石英阶段(S1)、主成矿贫硫化物‒石英阶段(S2)和成矿后石英‒方解石阶段(S3)。通过开展各阶段石英与方解石中流体包裹体的岩相学及显微测温研究,识别出三种类型流体包裹体:气液两相水溶液包裹体(L型)、含CO_(2)水溶液流体包裹体(C型)和纯CO_(2)流体包裹体(PC型)。各阶段流体包裹体的均一温度、盐度和压力分别为:S1阶段305~356℃、3.0%~9.4%NaCl_(eqv),145~239 MPa;S2阶段248~298℃、1.5%~7.9%NaCl_(eqv)、119~211 MPa;S3阶段157~254℃、0.7%~4.3%NaCl_(eqv)。基于静岩压力计算,S1和S2阶段的成矿深度分别为5.3~8.9 km和4.4~7.8 km。主成矿阶段L型与C型流体包裹体共生组合具有相似的均一温度,表明成矿流体发生了不混溶作用,金沉淀可能与此过程密切相关。S同位素分析结果显示:成矿前阶段黄铁矿(Py1)的δ^(34)S_(ΣS)值为−0.33‰~−0.15‰(中位值−0.26‰);主成矿阶段黄铁矿(Py2)的δ^(34)S_(ΣS)值为−1.30‰~0.69‰(中位值0.46‰),较Py1略有升高;而围岩(玄武岩)中黄铁矿(PyWR)的δ^(34)S_(v)-CDT值为−0.14‰~0.74‰(平均值0.30‰),与Py2相似,由此推测Py2的硫主要来源于地幔,并混入部分围岩硫。且Py2边缘振荡环带处δ^(34)S_(ΣS)值(−1.30‰)显著区别于环带内部(0.18‰~0.69‰),主成矿阶段δ^(34)S_(ΣS)值范围的扩大可能与流体不混溶作用有关。综合矿化特征、围岩蚀变、成矿流体性质及来源等地质特征,扎格依库都克金矿床为中‒浅成造山型金矿床。The Zhageyikuduke gold deposit is located on the southern margin of the Erqis Metallogenic Belt within the Altay Orogenic Belt in Xinjiang.The geometry and spatial distribution of gold orebodies are predominantly controlled by extensive NE-trending fault systems within the ore district.Distinct from other gold deposits in the Erqis Metallogenic Belt,the Zhageyikuduke deposit is characterized by its unique features of shallow burial depth and high-grade mineralization,presenting a significant scientific challenge in understanding its gold mineralization mechanism.Through systematic analysis of mineral assemblages and vein crosscutting relationships,we delineated three distinct hydrothermal mineralization stages:the early stage(pyrite-quartz,S1),middle stage(poor sulfide-quartz,S2),and late stage(quartz-calcite,S3).Comprehensive petrographic and microthermometric investigations of fluid inclusions in quartz and calcite of all stages revealed three primary fluid inclusion types:two-phase aqueous inclusions(type L),three-phase H2O-NaCl-CO_(2) inclusions(type C),and two-phase CO_(2) inclusions(type PC).The ore-forming fluids of stage S1 exhibited medium-high temperatures(305–356)℃with low salinity(3.0%–9.4%NaCl_(eqv))and low-medium pressures(145–239 MPa).Stage S2 fluids demonstrated homogenization temperatures of 248–298,℃salinities of 1.5%–7.9%NaCl_(eqv),and pressures of 119–211 MPa.The ore fluids evolved to low-medium temperatures(157–254)with℃low salinity(0.7%–4.3%NaCl_(eqv))during stage S3.Lithostatic pressure estimates suggest vein formation depths of 5.3–8.9 km for stage S1 and 4.4–7.8 km for stage S2,respectively.The coexistence of type L and type C fluid inclusions in stages S1 and S2 indicates fluid immiscibility,suggesting a potential link between gold precipitation and this immiscibility process.δ^(34)S_(ΣS) values of–0.33‰to–0.15‰(mean–0.26‰)for stage S1 pyrite(Py1)and–1.30‰to 0.69‰(mean 0.46‰)for stage S2 pyrite(Py2)indicate mantle-derived magma sources.The�

关 键 词：流体包裹体 黄铁矿S同位素 成矿流体特征 扎格依库都克金矿床 阿尔泰造山带 

分 类 号：P611[天文地球—矿床学]