Summary:
Savannah mineralisation.
The original Savannah sulphide rich nickel, copper and cobalt orebody is hosted by the layered mafic-ultramafic Savannah Intrusion which is enveloped by aluminous metasediments and para-gneisses of the Tickalara Metamorphics. The Savannah Orebody is mostly confined to a marginal norite unit up to 40 metres thick developed above the base of the intrusion. Areas of massive, matrix and disseminated sulphide mineralisation, dominated by pyrrhotite, chalcopyrite, pentlandite and minor pyrite occur throughout the marginal norite unit.
Prior to the development of the Savannah Open Pit, the marginal norite unit outcropped as a prominent 250 metre long limonite-goethite gossan with fresh sulphide mineralisation developing approximately 20 metres below surface. At approximately 500 metres below the surface, a significant sub-horizontal fault, the 500 Fault, cuts the orebody and offsets it 200 metres to the northwest. A similar fault at approximately 900 metres below surface, the 900 Fault, offsets the orebody a further 250 metres to the northwest. Mineralisation above the 500 Fault is referred to as the “Upper Zone”, between the 500 and 900 faults as the “Lower Zone” and below the 900 Fault as the “sub 900 Fault Zone”.
The Savannah mineralisation is 350m along strike (east), varies in thickness from 1 to 50m and averages 8m thick, from the surface to 1100m depth. The Savannah Resource reported herein relates to an area within 5,400mE to 6,300mE.
Savannah North mineralisation.
The SNM (Savannah North mineralisation) is based on mining ore associated with the Savannah Intrusion; a palaeo-proterozoic mafic/ultramafic magma conduit. The Ni-Cu-Co rich massive sulphide mineralisation occurs as “classic” magmatic breccias developed about the more primitive, MgO rich basal parts of the conduit.
Magmatic Ni-Cu-Co sulphide Resources hosted by the Savannah North Intrusion (SNI) located to the north of the Savannah Mine.
The Savannah North mineralisation dips moderately (40-45 degrees) to the north-west and comprises two main zones, the Upper Zone is developed on the basal contact of the North Olivine Gabbro, the second Lower Zone is a consistent remobilised zone of massive sulphide mineralisation, in part associated with the 500 Fault. Both zones are well defined by the drilling and the interpretation is considered sufficiently robust for resource modelling. Additional minor mineralised zones include 5 domains in the hanging wall position to the Upper Zone and a minor mineralized sub-vertical fault.
The Savannah North mineralisation has been defined over a strike length of approximately 1km. The Savannah North Resource reported herein relates to an area with a strike length of 1,125m from 5,300mE to 6,425mE and extends from 615m to 1,575m below surface with an average domain thickness of approximately 4 to 5 metres.