青海玉树尕龙格玛VMS型矿床流体包裹体及H-O-S-Pb同位素特征

发布时间：2018-04-06 23:18

  本文选题：三江成矿带　切入点：尕龙格玛　出处：《地球科学》2017年06期

【摘要】：为确定中国三江成矿带北段尕龙格玛VMS(volcanogenic massive sulfide)型矿床的成矿物理化学条件、成矿物质来源、成矿流体来源,探讨成矿机制,对矿体特征、流体包裹体显微测温和激光拉曼光谱分析以及S、Pb、H、O同位素进行了系统研究.矿体赋存于晚三叠世巴塘群英安质火山岩中,具有VMS型矿床的双层结构,由下部热液流体补给通道相的脉状-网脉状矿化系统和上部海底盆地卤水池喷气-化学沉积系统组成.通道相中流体包裹体可分为富气相包裹体和水溶液包裹体,均一温度为175.6~263.3℃,盐度为1.05%~6.29%NaCl eqv.,密度为0.820~0.935g/cm3,激光拉曼光谱分析包裹体气相成分为H2O、CO2和少量N2;沉积相重晶石中仅发育水溶液包裹体,均一温度为105.2~157.1℃,盐度为0.18%~5.55%NaCl eqv.,密度为0.735~1.173g/cm3,显示了流体由通道相向沉积相温度显著降低,盐度保持不变,密度变大的趋势,与典型VMS型矿床流体特征相似.氢氧同位素(δ18 OH2O:0.25‰~1.75‰,δD:-103.2‰~-65.3‰)研究表明,成矿流体主要来源于岩浆水和海水的混合.综合分析前人硫同位素研究结果(δ34 S:1.13‰~2.45‰,12.36‰~12.37‰)及本次获得硫同位素结果(δ34 S:-22.9‰~-14.7‰)表明硫来源于岩浆和细菌还原的海水硫酸盐或基底岩石.硫化物方铅矿的206 Pb/204 Pb、207 Pb/204 Pb和208Pb/204Pb分别为18.449~18.519、15.699~15.777和38.875~39.141,具有高放射性铅的特征,μ值为9.65~9.80,结果显示Pb等成矿物质主要来自于上地壳,并有岩浆物质参与成矿.成矿流体与海水的混合作用是尕龙格玛矿床形成的主要机制.
[Abstract]:In order to determine the ore-forming physicochemical conditions, ore-forming material sources, ore-forming fluid sources, metallogenic mechanism and ore-body characteristics of Galonggma VMS(volcanogenic massive sulfidetype deposits in the northern part of Sanjiang metallogenic belt, the ore-forming physical and chemical conditions, ore-forming material sources, ore-forming fluid sources, ore-forming mechanism andThe microthermometry of fluid inclusions, laser Raman spectroscopy, and the S _ (Pb) H _ (O) isotopes have been systematically studied.The orebody occurs in the late Triassic Batang Group amphibious volcanic rocks and has the double layer structure of VMS type deposit, which is composed of the vein and network vein mineralization system of the lower hydrothermal fluid supply channel phase and the upper seabed basin brine pool exhalation and chemical deposition system.The fluid inclusions in channel phase can be divided into gas-rich inclusions and aqueous inclusions. The homogenization temperature is 175.6C 263.3 鈩，

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