| 全长恩.东昆仑东段那更银多金属矿床成因：来自流体包裹体、锆石U-Pb年代学和稳定同位素的制约[J].地质与勘探,2022,58(6):1154-1169 |
| 东昆仑东段那更银多金属矿床成因：来自流体包裹体、锆石U-Pb年代学和稳定同位素的制约 |
| Genesis of the Nagengsilver polymetallic deposit in the eastern section of East Kunlun: Constraints from fluid inclusions, zircon U-Pb chronology and stable isotopes |
| 投稿时间：2022-03-23 修订日期：2022-06-03 |
| DOI：10.12134/j.dzykt.2022.06.002 |
| 中文关键词: 流体包裹体 锆石U-Pb定年 H-O-S同位素 那更银多金属矿 东昆仑东段 |
| 英文关键词: fluid inclusions, zircon U-Pb dating, H-O-S isotope, Nageng silver polymetallic ore, eastern section of East Kunlun |
| 基金项目:青海省科技计划项目“东昆仑东段与岩浆-火山热液有关的铜-铅-锌-银多金属成矿系统形成及找矿方向研究”（编号：2020-ZJ-762）资助 |
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| 中文摘要: |
| 那更银多金属矿床位于东昆仑成矿带东段，是青海境内截至目前发现的首个大型独立银矿床，对其开展成矿研究具有突出的代表性。本文对矿区内的矿化流纹岩、含矿石英脉进行了流体包裹体、H-O-S同位素以及U-Pb年代学研究，探讨该矿床成矿流体来源和成因类型。对流纹岩中的锆石进行U-Pb测年获得的加权平均年龄为219.2±1.4 Ma，属于晚三叠世。矿化石英脉样品中流体包裹体NaCl-H2O-CO2体系温度范围为75~346 ℃，盐度（NaCleqv）为2.57%~7.86%，具有中低温、低盐度特征，并计算得出其成矿深度为0.330~1.046 km。δDSMOW值和δ18OH2O值的变化范围分别为-118.2‰~-86.7‰和-11.02‰~10.02‰，黄铁矿、闪锌矿、方铅矿的δ34S值为-6.1‰~0.5‰，指示成矿流体主要来源于深源岩浆水与大气水的混合体系。综合分析认为，含矿流纹质熔浆在近地表结晶过程中析出的含水流体，沿断裂带上升至浅部开放体系时，在静水条件下减压沸腾引发流体系统中的温度和硫逸度快速降低，从而导致银、铅、锌等元素沉淀成矿，其成因类型属于浅成低温火山热液型。 |
| 英文摘要: |
| The Nageng silver polymetallic deposit, located in the eastern section of the East Kunlun metallogenic belt, is the first large-scale independent silver deposit discovered in Qinghai Province so far. It is a prominent representative to carry out metallogenic research. This work studied the fluid inclusions, H-O-S isotopes and U-Pb chronology of mineralized rhyolites and ore-bearing quartz veins in the deposit to discuss the ore-forming fluid source and genetic type. The weighted average age of the zircons in rhyolite obtained by U-Pb dating is 219.2±1.4 Ma, belonging to the Late Triassic. The temperature range of NaCl-H2O-CO2 system of fluid inclusions in mineralized quartz vein samples is 75~346 ℃, and the salinity(NaCleqv) ranges in 2.57%~7.86%. The mineralization depth is calculated to be 0.330~1.046 km.TheδDSMOW values vary form-118.2‰ to -86.7‰, and theδ18OH2O valueslie between -11.02‰ and 10.02‰. The δ34S values of pyrite, sphalerite and galena range between -6.1‰ and 0.5‰. It is indicated that the ore-forming fluids mainly come from the mixed system of deep-seated magmatic water and atmospheric water. Comprehensive analysis shows that when the aqueous fluid precipitated from the ore-bearing rhyolitic melt in the process of near surface crystallization rose to the shallow open system along the fault zone, the decompression boiling under hydrostatic conditions caused the rapid reduction of temperature and sulfur fugacity in the fluid system, resulting in the precipitation and mineralization of elements such as silver, lead and zinc. Its genetic type belongs to epithermal volcanic hydrothermal type. |
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