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为探讨甘肃小铁山矿床的成矿流体来源、性质及其演化过程,对其含矿石英脉、重晶石样品开展了系统的流体包裹体研究。结果表明,包裹体类型主要为气液两相包裹体、纯气体包裹体、纯液体包裹体以及含CO_2的三相包裹体。显微测温结果表明,小铁山矿床下盘脉状矿体中石英的流体包裹体的均一温度为174~452℃,盐度为0.88%~9.86%NaCl_(eqv);重晶石中流体包裹体的均一温度为149~388℃,盐度为2.07%~12.16%;块状矿体中的流体包裹体均一温度为178~296℃,盐度为1.91%~14.46%NaCl_(eqv)。氢氧同位素研究显示,含矿石英脉状中δ~(18)O_(H_2O)为-1.14‰~4.68‰,δD_(V-SMOW)为-88.0‰~-153.2‰,结合包裹体的岩相学、流体性质等特征,推断成矿热液应为岩浆流体与加热海水的混合流体。
In order to explore the source, nature and evolution of ore-forming fluid in Xiaoshan iron deposit, Gansu, systematic fluid inclusion studies on ore-bearing quartz veins and barite samples were carried out. The results show that the main types of inclusions are gas-liquid two-phase inclusions, pure gas inclusions, pure liquid inclusions and three-phase inclusions containing CO_2. The microscopic temperature measurement results show that the homogenization temperature of quartz inclusions in the vein of the lower part of the Xiaotieshan deposit is 174 ~ 452 ℃ and the salinity is 0.88% ~ 9.86% NaCl_ (eqv). The fluid in the barite The homogenization temperature of the inclusions is 149 ~ 388 ℃ and the salinities are 2.07% ~ 12.16%. The homogenization temperatures of the fluid inclusions in the massive ore bodies are 178 ~ 296 ℃ and the salinities are 1.91% ~ 14.46% NaCl eqv. The study of hydrogen and oxygen isotopes shows that δ 18 O_ (H_2O) in the ore-bearing veinlets is -1.14 ‰ ~ 4.68 ‰ and δD_ (V-SMOW) is -88.0 ‰ ~ -153.2 ‰, combining the lithofacies of the inclusions It is inferred that the mineralization hydrothermal fluid should be a mixed fluid of magma fluid and heated seawater.