Occhipinti, Dr Sandra , Metelka, Dr Vaclav1, Lindsay, Dr Mark2, Aitken,Dr Alan2
1CSIRO, Kensington, Australia; 2Centre of Exploration Targeting, University of Western Australia, Crawley, Australia
Opening up greenfields regions for minerals exploration programs is best facilitated through the understanding of regional minerals prospectivity. The Capricorn Orogen is a greenfields-dominated region, for which a multicommodity mineral systems analysis has been completed forming the basis for new prospectivity analysis and mapping. Known mineral occurrences or deposits in the region formed between the Paleoproterozoic and Neoproterozoic. Mineralisation can be related to basin development and orogenesis in the region, in turn related to periods of supercontinent assembly and breakup. These were manifested in the region through the contractional 2005–1950 Ma Glenburgh, 1830–1780 Ma Capricorn, and c. 1030–950 Ma Edmundian and 920–850 Ma Kuparr orogenies. These periods of orogenesis were preceded and interspersed with periods of subsidence, perhaps including the 1680–1620 Mangaroon Orogeny, which led to the development of volcanosedimentary and sedimentary basins throughout the region. Prospectivity models were generated for several commodity groups of various ages and ore genesis mechanisms, including combinations of Ni, Cu, PGEs, V, Ti, Au, Pb, Zn, channel Fe and U. The work has found a link between key mineral systems and a spatial relationship between disparate styles of mineral deposits in the region. Crustal-scale tectonic architecture was analysed by allying a 2D map view geological-geophysical interpretation with 2.5D magnetic and gravity joint inversions of selected profiles, a 3D Moho model, and by inference from 2D and 3D magnetotelluric models, 2D reflection seismic images and 3D passive seismic models from the region. This work clearly illustrates that different ‘zones’ of the Capricorn Orogen are prospective for different commodity groups due to the tectonic environment in which they developed. Major crustal-scale deformational zones intrinsically control the location of known ore deposits in the area, and are inferred to be sites of fluid migration associated with ore deposition. Of these, some are considered to be of Archean origin, whereas others are thought to have first developed during the early Paleoproterozoic. In both cases, many structures have been re-activated through time, influencing the formation of basins over them and perhaps the formation of ore deposits.
Sandra Occhipinti is a geologist with over 20 years experience in regional mapping, geophysical interpretation, mineral systems analysis and structural geology. She is the research director of the Discovery Program, CSIRO Mineral Resources