1. Analysis of the weathering profile associated with the near surface 2 Lens & B Lode of the Giant Broken Hill PB-ZN-AG Orebody, Perilya Limited's Southern Operation, Broken Hill NSW
- Author
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Graham, Luke Michael and Graham, Luke Michael
- Abstract
The Southern Operations (CML 8) is situated within the Curnamona Province of Western New South Wales, along the southern extent of the Giant Broken Hill Pb-Zn-Ag orebody. Previous estimates of the near surface reserves of both 2 Lens and B Lode between sections 10 – 30 have been calculated to consist of 705 kT of ore at 81 kT combined Pb/Zn. However the metallurgical recovery (floatability) of these reserves may be substantially lower than previously estimated due to the oxidation of hypogene ore following climatic adjustment (prevailing arid regime) during the last glacial maximum. Therefore whilst the identification of a secondary zone within the central mining field has been substantially documented by previous academics, with mineral assemblages correlating to a two-phase oxidation cycle following the decline in the regions palaeo-water table (illuvial zone), the irregularity of the orebody‟s geometry, mineralogy (internal stratification) and structural geology indicates that a simple paragenetic model cannot be applied over the entire mine sequence. As a result field-based observations, whole rock geochemistry and petrographic analysis were used to describe the mineralogical/elemental nature of the secondary zone within the southern mining district, relative to observations made by earlier academics within the central mining leases. These investigations further support the notion of two-phase oxidation cycle with samples within both the gossanous and complex carbonate zone of 2 Lens and B Lode exhibiting a diversification of secondary minerals within several morphological forms, relative to the overprinting of the palaeo-supergene blanket following redissolution. However in comparison with the central mining district the southern extent of 2 Lens and B Lode notably displays a less extensive secondary zone, with only an estimated 1681.53 t (2.076% of the reserve) of pre-existing hypogene ore having undergone oxidation to form secondary minerals (i.e. cerussite a
- Published
- 2014