The two East Kimberley projects occur within 50-100km of Wyndham with limited road access but good access to support services in Kununurra. Â Some of the areas are subject to travel and access restrictions unless approved by the traditional owners.
Figure 1 Regional setting of the East Kimberley copper projects applied for by AFR
The East Kimberley plateaux comprises flat to near flat lying clastic sediments and volcanic rocks of the Kimberley Group. The lower part of the Kimberley Group contains the Wunaamin Miliwundi sandstones and the Carson Volcanics comprising massive, altered basalts and minor clastic sediments. These are overlain by the massive red siltstones and minor shales of the Elgee Siltstone, and then in turn by the Pentecost Sandstone, comprising Lower, Middle and Upper units.
Known copper occurrences have been mapped within or adjacent to the shale units of the Elgee Siltstone and associated with glauconitic sandstones at the base of the Middle Pentecost Sandstone (see Figure 2). In both instances, these horizons represent reduced sequences which make favourable hosts for copper sulphide precipitation. Copper may have been sourced from the underlying altered basalts of the Carson Volcanics. Copper accumulation may have occurred at structural sites in the reduced host sequences such as fault margins to sub-basins and along the edges of uplifted domes.
Figure 2 District scale geology showing copper occurrences at two distinct stratigraphic positions within the Palaeo-Proterozoic Kimberley Group sediments.
The two projects under application cover known copper occurrences that represent both structural settings:
- The Cambridge Gulf Project contains several known copper occurrences in both the Elgee Siltstone and the base of the Middle Pentecost Sandstone. The area shows significant sub-basin marginal faulting, which may have acted as fluid pathways for copper bearing solutions to move from the underlying Carson Volcanics into the stratigraphically higher trap sites.
- The Menuair Dome Project, as the name implies, contains several copper occurrences around the margins of the Menuair Dome, with copper occurring in both favourable stratigraphic horizons.
No known exploration of any significance for copper has been documented for these two project areas, representing a first mover opportunity for African Energy.
