Summary:
The Tropicana Gold Project area lies east of a northeast trending magnetic feature, interpreted to be the major tectonic suture between the Yilgarn Craton and the Proterozoic Albany-Fraser Orogen that extends over 700km. The gold deposit is hosted in Archaean gneissic metamorphic rocks (ca. 2,640Ma) with cover sequences generally 10 to 30m thick resulting in the mineral deposit not being exposed at surface.
The 5km long strike of gold mineralisation at Tropicana is subdivided into five shear offset zones from north to south – Boston Shaker, Tropicana, Havana, Havana Deeps, and Havana South. The mineralised corridor is ~1.2km wide and up to 1.5km down dip to the current deepest drill intercepts. Within each zone the gold mineralisation trends north to northeast. Gold is concentrated in ~2m to ~50m thick subparallel layers within the ‘favourable horizon’ which comprises quartz-feldspar gneiss units.
Together, the Tropicana, Havana, Havana South and Boston Shaker deposits define a northeast trending mineralised corridor, approximately 1.2km wide and 5km long that has been tested to a vertical depth of more than 1,200m. The Mineral Resource remains open down-dip from the Tropicana, Havana and Boston Shaker deposits and has the potential to be extended to the north and south. Neither the immediate metamorphic host rocks nor the mineralised zones are exposed at surface due to the presence of widespread younger cover sequences.
The Tropicana area is covered by a 10m to 30m thick unconformable cover of Permian and Tertiary sedimentary rocks that have Tertiary lateritic weathering. In some areas the cover sequence also includes Holocene aeolian sands and colluvium.
The Tropicana deposit comprises a mineralised zone up to 50m thick, hosted predominantly in quartzo feldspathic gneiss with a garnet-gneiss dominated hangingwall package. The mineralisation is comprised of subordinate thin (3 to 5m), discontinuous mineralised lenses that typically return intercepts of >0.5g/t gold. The Havana deposit comprises a lower, laterally continuous, higher-grade lode up to 50m thick that is overlain, in the central and southern parts of the pit, by stacked, typically lower-grade and thinner (up to 25m thick) mineralised zones. Havana is also dominantly hosted in quartzo-feldspathic gneiss, again with a garnet gneiss dominated hangingwall.
Mineralisation is accompanied by pyrite (2% to 8%) with accessory pyrrhotite, chalcopyrite and other minor sulphides and tellurides. The gold mineralisation is related to shear planes that postdate the main gneissic fabric developed during peak granulite-facies metamorphism.
Mineralisation is characterised by pyrite disseminations, bands and crackle veins within altered quartz-feldspar gneiss. Higher grades are associated with close-spaced veins and sericite and biotite alteration.
Mineralisation presents as stacked higher grade lenses within a low-grade alteration envelope.
Dimensions
The underground MRE extends from the base of the open pit MRE below the open pit designs, extending down dip by up to a plan length of 1300m at Havana and Boston Shaker and 500m at Tropicana.
The overall reported MRE has dimensions of approximately 5km along strike, up to 1.5km wide and up to 850m deep, spanning all the major deposits.