韩朝辉, 宋玉财, 刘英超, 侯增谦, 程杨, 翟忠保. 伊朗Ahangaran铅(铜)矿床特征及成因[J]. 地质通报, 2020, 39(10): 1625-1638.
    引用本文: 韩朝辉, 宋玉财, 刘英超, 侯增谦, 程杨, 翟忠保. 伊朗Ahangaran铅(铜)矿床特征及成因[J]. 地质通报, 2020, 39(10): 1625-1638.
    HAN Chaohui, SONG Yucai, LIU Yingchao, HOU Zengqian, CHENG Yang, ZHAI Zhongbao. Characteristics and genesis of the Ahangaran Pb Cu deposit Iran[J]. Geological Bulletin of China, 2020, 39(10): 1625-1638.
    Citation: HAN Chaohui, SONG Yucai, LIU Yingchao, HOU Zengqian, CHENG Yang, ZHAI Zhongbao. Characteristics and genesis of the Ahangaran Pb Cu deposit Iran[J]. Geological Bulletin of China, 2020, 39(10): 1625-1638.

    伊朗Ahangaran铅(铜)矿床特征及成因

    Characteristics and genesis of the Ahangaran Pb Cu deposit Iran

    • 摘要: Ahangaran铅(铜)矿床位于伊朗地块(北部)与阿拉伯板块(南部)碰撞形成的扎格罗斯造山带的Sanandaj-Sirjan带内,该碰撞发生在新生代,赋矿围岩为下白垩统白云质灰岩。矿体多呈顺层的透镜状和穿层的脉状产出,成矿前沉淀细粒石英,成矿期出现白云石、方解石、重晶石、粗粒石英、方铅矿、黄铜矿、黄铁矿、黝铜矿。流体包裹体研究显示,成矿流体为Cl--Na+-Ca2+-Mg2+体系,均一温度介于108~210℃之间,盐度介于7%~29% NaCl eq之间,结合脉石矿物和包裹体的碳-氢-氧同位素特征,显示成矿流体主要来自盆地卤水,但不排除有岩浆流体的贡献,在成矿过程中成矿流体与碳酸盐围岩发生相互作用,使围岩发生溶解。重晶石δ34S值介于18.7‰~22.7‰之间,硫化物中δ34S值介于-3.1‰~9.7‰之间,推测还原硫可能主要来自硫酸盐的生物还原(BSR),也不排除有机质热化学还原(TSR)作用的贡献。方铅矿206Pb/204Pb值介于18.4083~18.4054之间,207Pb/204Pb值介于15.6512~15.6548之间,208Pb/204Pb值介于38.5628~38.5515之间,与区域铅锌成矿带内其他赋存在碳酸盐岩中铅锌矿床的铅同位素特征相似,说明这些矿床中金属来源均与经历了"造山"作用的上地壳岩石有关。尽管该矿床矿化和成矿流体特征与密西西比河谷型(MVT)矿床相似,但其富石英和含铜的特征与和岩浆有关的碳酸盐岩交代型矿床(CRD)更接近,建议将该矿床归为后一类。

       

      Abstract: The Ahangaran Pb(Cu) deposit is located in the Sanandaj-Sirjan metamorphic zone of the Zagros orogenic belt, a Cenozoic continental collisional zone between Arabian(south) and Iran(north) blocks. The deposit is hosted in Lower Cretaceous dolomitic limestone and has conformable and lenticular orebodies and bed-crosscutting ore veins. Pre-ore stage of minerals are fine-grained quartz, and ore stage of minerals are composed of dolomite, barite, calcite, coarse-grained quartz, galena, chalcopyrite, pyrite, and tetrahedrite. The study of the fluid inclusions shows that the ore fluids are a Cl--Na+-Ca2+-Mg2+ system, with homogenization temperatures from 108℃ to 210℃ and the salinities from 7%NaCl eq to 29%NaCl eq. Combined with data of C-H-O isotopes from ore stage hydrothermal gangue minerals and associated fluid inclusions, the authors hold that the ore fluids were mainly derived from basinal brine, with or without contribution from magmatic fluids. The mineralization process led to the dissolution of the host carbonate. The δ34S values of barite range from 18.7‰ to 22.7‰, and sulfides range from -3.1‰ to 9.7‰, suggesting that the reduced sulfur was probably the result of biological sulfate reduction(BSR). But this does not exclude the probable contribution of reduced sulfur from thermochemical sulfate reduction(TSR). The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of galena are 18.4083~18.454, 15.6512~15.6548, and 38.5628~38.5515, respectively, which are similar to those of the other Pb-Zn deposits in this region, i.e., the Malayer-Esfahan carbonated-hosted Pb-Zn metallogenic belt. It is suggested that their metals were derived from the same upper crustal rocks. Although the Ahangaran deposit shares some similarities with Mississippi Valley-type(MVT) deposits, the enrichment of ore stage quartz and copper sulfides suggests that the deposit may be classified as a magmatic-related carbonate-replacement-type deposit.

       

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