Exploration

The Tropicana deposit was discovered in 2005 after AngloGold Ashanti followed up an unexplained gold-in-soil anomaly Independence had recognised in public domain regional data collected in the 1990s.

Discovered in a remote, barely-explored area along an ancient collision zone between the Yilgarn Craton and the Albany-Fraser Province, not previously thought to be prospective for gold, Tropicana is the most significant gold find in Australia for more than a decade.

The discovery prompted the JV partners to peg more than 15,000 square kilometres of tenements in what is now recognised to be a new gold province.

As well exploring in the immediate vicinity of what is now the Tropicana Gold Mine, the partners have been carrying out comprehensive regional geochemical and geophysical surveys.

On a regional scale, first pass aircore drilling programs over domains of anomalous soil/auger geochemistry have, in many areas, returned anomalous results warranting follow up exploration.

District scale gold potential is delineated by a corridor of anomalism extending 220 km to the south-west of Tropicana to the Beachcomber prospect and 30 km to the north-east to the Voodoo Child prospect.

Drilling at the Madras and Sanpan prospects in 2014 and 2015, located 25km south and 50km southeast respectively of the Tropicana Gold Mine, returned significant results, including, but not limited to 15 metres at 5.08 g/t, 25m at 2.47 g/t and 17m at 4.22 g/t. Initial results from Madras were within a zone of supergene mineralisation spatially associated with a broad shear zone. 

Exploration techniques used by the joint venture include geochemical sampling and geophysical surveys along with aircore, RC and diamond drilling.

By the mid 2014, the JV tenement holding had been reduced to just under 10,000 sq km.

The exploration team continues to test promising targets within trucking distance of the mine along with regional exploration targets. Outside of the immediate mine area the exploration team is testing promising targets within trucking distance of the mill, along with regional targets and will spend approximately $12 million on near-mine exploration and $5 million on the regional search.

In the mine area the Tropicana, Havana and Boston Shaker deposits have been drill-tested to a vertical depth of 1,000m. The resource remains open down dip at all three deposits and to the south of the Havana deposit.

A major milestone was achieved in 2013 when approval was obtained to explore within the EPBC Referral area (see Environmental Compliance section for more detail). This will allow exploration to occur on a number of greenfields tenements for the first time.

A 3D seismic survey undertaken in 2014 also generated an invaluable dataset and enabled the company to image the mineralised zones down dip of the Tropicana ore bodies and generate a structural model to help cost-effectively target deep drill holes.

The first drill testing of these targets has returned encouraging results and confmmred the structural interpretation and the seismic survey data will now support a substantive resource definition drilling programme as part of the mining study.