| 杨玉林,李光明,杨洪伟,付建刚,李应栩,郭伟康.西藏洛扎县次麦铅锌银多金属矿床的成矿流体研究:来自流体包裹体及 H-O同位素的证据[J].矿产勘查,2025,16(4):777-791 |
| 西藏洛扎县次麦铅锌银多金属矿床的成矿流体研究:来自流体包裹体及 H-O同位素的证据 |
| Study on ore-forming fluids of the Cimai Pb-Zn-Ag polymetallic deposit in Luozha County, Xizang Autonomous Region: Evidence from fluid inclusions and H-O isotopes |
| 投稿时间：2023-10-26 |
| DOI：10.20008/j.kckc.202504009 |
| 中文关键词: 流体包裹体 H-O同位素 次麦铅锌银多金属矿床 成矿流体 西藏洛扎县 |
| 英文关键词: fluid inclusion H-O isotope Cimai Pb-Zn-Ag polymetallic deposit ore-forming fluid Luozha County, Xizang Autonomous Region |
| 基金项目:本文受国家重点研发计划项目(2021YFC2901903)资助。 |
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| 中文摘要: |
| 西藏次麦铅锌银多金属矿床位于喜马拉雅成矿带东段，以铅锌为主伴生银，并产出锡铁矿伴生钨的特征，明显不同于区域上其他的铅锌多金属矿床。金属矿物以方铅矿、闪锌矿、黄铁矿为主，次为磁铁矿、黄铜矿等；非金属矿物以绿帘石为主，次为透辉石、透闪石、石英、方解石、阳起石、符山石等。研究显示，在室温下，与铅锌共生的石英流体包裹体类型主要为气液两相流体包裹体；激光拉曼分析显示流体包裹体中气液相主要为 H2O，含少量气相 CO2。显微测温研究表明，金属硫化物阶段均一温度为 227~337.2 ℃，平均值为 274.3 ℃；冰点温度为-6.2~-0.5 ℃，盐度为 0.9%~9.8% NaCleqv，平均值为 3.9% NaCleqv，对应的流体压力为 555.0~939.7 bar，平均值为 699.2 bar；成矿流体属中高温、低盐度、中高压的 NaCl-H2O体系。石英的 H-O同位素指示成矿流体经历了两阶段演化，早期为与富 δD的沉积地层发生水岩反应的变质流体，后期为含矿热液加入的混合流体。研究认为流体混合作用和含矿流体的地球化学障被打破应是次麦铅锌银多金属矿床中铅锌等金属富集成矿的主要因素。次麦铅锌银多金属矿床为研究受穹隆构造控制的矽卡岩型铅锌多金属矿床提供理想对象。 |
| 英文摘要: |
| The Cimai Pb-Zn polymetallic deposit in Xizang Autonomous Region is located in the eastern partof the Himalayan metallogenic belt. It mainly produces silver associated with lead and zinc, and produces tin ironassociated tungsten, which is obviously different from other Pb-Zn polymetallic deposits in the region. The main me-tallic minerals are galena, sphalerite and pyrite, followed by magnetite and chalcopyrite. The non-metallic mineralsare mainly epidote, followed by diopside, tremolite, quartz, calcite, actinite, Fushan stone, etc. The results show thatat room temperature, the types of quartz fluid inclusions associated with lead and zinc are mainly gas-liquid two-phase fluid inclusions. Laser Raman analysis shows that the gas-liquid phase in the fluid inclusions is mainly H2O and contains a small amount of gas-phase CO2. Microthermometry shows that the phase homogenization temperatureof metal sulfide ranges from 227 to 337.2 ℃, with an average value of 274.3 ℃. The freezing temperature rangesfrom -6.2 to -0.5 ℃, the salinity ranges from 0.9% to 9.8% NaCleqv with an average value of 3.9% NaCleqv, and thecorresponding fluid pressure ranges from 555.0 to 939.7 bar with an average value of 699.2 bar. The ore-formingfluid belongs to the NaCl-H2O system with medium high temperature, low salinity and medium high pressure. TheH-O isotope of quartz indicates that the ore-forming fluid has undergone two stages of evolution. In the early stage,the ore-forming fluid is the metamorphic fluid that reacts with the δD-rich sedimentary strata, and in the late stage,the ore-bearing hydrothermal fluid is the mixed fluid. It is concluded that fluid mixing and the breaking of geo-chemical barrier of ore-bearing fluid should be the main factors for the enrichment and mineralization of Pb and Znin the Cimai Pb-Zn polymetallic deposit. The Cimai Pb-Zn-Ag polymetallic deposit provides an ideal object for thestudy of skarn type Pb-Zn polymetallic deposit controlled by vault structure. |
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