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Deposit Synonyms
Mineral District
Deposit Summary
minor vein style Uranium mineralisation associated with IOCG deposit. Best assay result of 145ppm U between 113-116m in drillhole MPRC029.
Deposit Description
NORTH PORTIA, Cu-Au-(Mo-Co-U) mineralisation located under cover on the eastern flank of the Benagerie Ridge Magnetic Complex, which occupied the core of a regional anticline in the Palaeoproterozoic basement metasediment. The mineralisation followed a zone around this core, concealed beneath 70-80m of Cainozoic sediment. The mineralised sequence was associated with the interface between oxidised rock of the Curnamona Group, and more reduced rocks of the overlying Bimba-Portia Formation and Strathearn Group. The zone of primary sulphides was overlain by a significant resource of secondary Cu-Au-Mo mineralisation typically weathered to saprolitic clays. Ore mineralogy was dominantly chalcocite, bornite, and chalcopyrite, with significant levels of Mo.
Drilling identified mineralisation as bedding plane replacement and veins within a ~200m thick sequence of low-grade metamorphic, highly albitised metasediment contained numerous carbonate-rich domains intercalated with evaporitic metasediment. A SHRIMP U-Pb zircon age of the host rock was1703-6Ma. The metasediment was overlain by carbonaceous phyllite, and underlain by a dominantly albite-magnetite-hematite unit. Hydrothermal monazite formed during the albitisation event gave SHRIMP U-Pb ages of ~1630Ma. Monazite associated with the mineralisation yielded SHRIMP U-Pb ages of ~1605Ma. Metal source was possibly the numerous, highly fractionated and altered diorite bodies known to be present on the Benagerie Ridge (1595-1580Ma). The mineralisation has a distinctive geochemical association of Cu, Au, Mo, W, Bi, and a metal zonation of Cu-Au grading to Pb-Zn.
Research thesis by J. Bryant, 1999, indicated an ore paragenesis of 8 stages, with the most significant event being albitisation that preceded mineralisation, and affecting all rocks of the mineralised sequence. In particular the development of stockwork veining, and pervasive replacement of the original mineralogy.
Resource drilling by Havilah Resources on the shallower secondary copper-gold resource has returned intercepts of high grades of copper, significant gold and molybdenum, with down dip transitions into wide zones of primary sulphide mineralisation, ie 74m @ 1.065Cu, 1.2g/tAu, 238ppm Mo. The drilling appears to have closed off the extent of mineralisation along strike, but not down plunge. Drillhole MPRC029 penetrated minor vein style uranium mineralisation, with a best assay of 145ppm U from 113-116m.
Discovery Year
? 2005
Commodities
Copper, Gold, Molybdenum, Cobalt
Ore Minerals
Chalcopyrite, Gold, Molybdenite
Gangue Minerals
Albite, Quartz
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