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Alteration and mineralization styles related to high-grade iron ore in the eastern Hamersley Province, Western Australia

Hamersley province, Western Australia

This two-year postdoctoral project will widely extend (and possibly revise) the knowledge of iron ore genesis and controls in the eastern Hamersley basin. The study is desiged to integrate the extensive, but unpublished, database of BHPB Iron Ore with new data obtained from field and laboratory work. It aims to test the present genetic model, and eventually generate revised genetic and new conceptual exploration models.  

The eastern Hamersley basin hosts a great number of largely fault-controlled, high-grade martite-microplaty and martite-goethite iron ore deposits within the Brockman and Marra Mamba iron formations (e.g. Mt Whaleback and Mining Area C, respectively). However, the understanding of ore formation throughout the enire Hamersley basin is limited, which has led to contrasting genetic models. These are namely the supergene-metamorphic and supergene-modified hydrothermal models, both explaining microplaty hematite formation differently, and the so far untested electrochemical cell hypothesis for deep-seated martite-goethite ore.

However, recent findings show that fluid sources and processes in space and time are too complicated to be explained by either of the models alone: for example, there is a locally close spatial relationship between both martite-microplaty and martite-goethite ore and martite-microplaty ore has been found in the Marra Mamba Formation (Clout 2005), concealed iron ore bodies below largely unaltered BIF were delineated (Taylor et al. 2001), and carbonate alteration in wall rocks at Mt. Whaleback has been observed (Webb et al. 2004). The latter may indicate genetic similarities to major deposits in the central Hamersley basin (e.g., Thorne et al. 2004). These intruiging findings are to be investigated and may lead to a revision of existing models.