澳大利亚西部哈默斯利铁成矿省BIF富铁矿的成矿特征与控矿因素

    Metallogenic characteristics and ore-control factors of the high-grade BIF of the Hamersley iron province in western Australia

    • 摘要: 澳大利亚西部哈默斯利铁成矿省含有世界级高品位的赤铁矿体。主要铁矿床包括芒特维尔贝克、汤姆普莱斯山、帕拉伯杜等,它们均产于元古宙早期布罗克曼BIF型含铁建造中。高品位铁矿体的空间分布明显受到元古宙区域隆起和拉张环境下形成的古老正断层系统的控制。该成矿省高品位铁矿层的形成可分为3个阶段:第1阶段为深层阶段,该阶段硅从含铁建造中淋滤出来,留下薄层状富含铁氧化物、碳酸盐岩、硅酸镁和磷灰石的残余物;第2阶段为深部大气水氧化阶段,该阶段含铁建造的磁铁矿—菱镁矿组合被氧化为赤铁矿—铁白云石,并以发育假象赤铁矿为特征;第3阶段为浅层风化作用。通过对成矿特征和成矿模式的总结,认为成矿时代、断层、褶皱等构造特征及流体和表生风化作用是富铁矿床形成的主要控矿因素。

       

      Abstract: The Hamersley iron province of Western Australia contains the world-class high-grade hematite deposits hosted within the Lower Proterozoic Brockman Iron Formation (BIF-type) in Mount Tom Price, Mount Whaleback, and Paraburdoo. Spatially, these deposits are structurally constrained by old normal fault systems formed during a period of major uplift and extension in Proterozoic. The formation of the Hamersley high-grade hematite deposits could be divided into three stages, i.e. the first stage or the hypogene metallogenic stage, during which silica was removed, leaving thinned residues rich in iron oxides, carbonates, magnesium silicates and apatite; the second deep meteoric stage, during which magnetite-siderite assemblage was oxidized into hematite-ankerite; the third stage or the supergene stage. Based on a discussion on the metallogenic characteristics and the ore genesis model, the authors have found that the ore-forming epochs, the tectonic characteristics such as faults and folds, fluids, and the supergene weathering constituted the main ore-control factors for the formation of the high-grade iron deposits.

       

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