Epithermal deposits of the Central Pilbara tectonic zone Description and exploration significance

Epthermal textures have recently been recognised in north-northwest-trending quartz veins hosted by Mesoarchaean rocks of the Central Pilbara tectonic zone. These veins occur near the inferred unconformity with the overlying Neoarchaean Fortescue Group. Geological relationships and Pb isotope model ages of possibly correlative mineralisation suggest that this epithermal mineralising event was associated with the opening and early development of the Hamersley Basin at around 2750 million years. These results have significance not only to the potential for the Pilbara Craton and overlying Fortescue Group, but also to other Archaean terranes; preservation, not age, is the determining factor for Archaean epithermal mineralisation.