The Ernest Giles project is located 250km north-east of Laverton in the Yilgarn in central Western Australia. The project covers over 2,000sq km of unexplored Yilgarn Craton hosting greenstone belts and intrusives with over 210km of strike of prospective rocks.
Greatland believes the project has the potential to deliver significant shareholder value with the discovery of large +5 mil oz gold camps and 5-10Mt nickel deposits.
The eastern Yilgarn Craton is the most highly mineralised area in Western Australia, containing numerous gold deposits e.g. Laverton +25mil oz, Tropicana +5mil oz, Yamarna +6mil oz, all of which are found in greenstone belts of similar size to that in the Ernest Giles area.
Due to its remote nature and cover sequences there has been only limited previous exploration in the Ernest Giles area. CRA Exploration and WMC Exploration explored parts of the project area between 1996 and 1999. Limited reverse circulation (RC) drill holes were completed by WMC Exploration which confirmed the presence of gold prospective Archean rocks at a depth of 170m.
Greatland Gold results so far are very encouraging considering the unexplored nature of the property.
Interpretation of aeromagnetics has outlined numerous gold prospective targets under recent desert sand and sediments. These targets are at various stages of exploration.
Surface sampling has returned very high results with up to 338ppb Au in soil, in target areas which are yet to be drilled.
Over 7,600m of RC and 1,500m of diamond drilling by Greatland in other targeted areas revealed large alteration systems and gold mineralisation over 1g/t.
The 2016 RC drill programme comprised 23 holes for 5,581m. Hole locations were based on a broad spaced grid pattern of 1,600m x 800m. Holes were designed to test basement lithologies for gold mineralisation and also test beneath surface geochemical anomalies.
Mineralisation was observed in 13 of the 23 holes. Initial 4m composite analysis of drill spoils shows gold anomalism between 5 and 95ppb in more than 10 holes peaking at 784ppb. Several holes exhibiting gold anomalous zones over tens of metres, for example ERC011 140-200m (60m) peaking at 0.78g/t gold with mineralisation at end of hole, and ERC014 224-278m (54m) peaking at 0.17g/t gold also with mineralisation at end of hole.
Results of drilling outline two, large, north-west trending zones of mineralisation. The Western Zone being 6km long and 1.5km wide and open to the north, and the Eastern Zone 2km long and 1.5km wide which remains open to the north and south.
The cover sequence was not as thick as expected with shallowest intercept of 119m, but generally around 180m depending on location. Varying basement lithologies were intersected including basalt, band iron formation and syenite. Silica and biotite alteration were prevalent with quartz veining and sulphide mineralisation.
Additional 1m sampling of several zones of interest was undertaken to confirm preliminary results and better define mineralisation. Only holes ERC011, ERC013 and ERC014 were sampled with a total of 174 single metre samples collected. Many significant gold results were returned up to 2g/t, including 2m at 1.51g/t and 1m at 1.54g/t. Anomalous silver was also noted in many samples. Results confirm mineralisation is present over a large area and suggest that Greatland has discovered a new gold province in this largely unexplored region.
Recent acquisition of a large, detailed airborne survey has highlighted several new structural targets suitable for gold mineralisation.
The Ernest Giles project area clearly shows similarities of size, structure, and magnetic signatures to the Mt Magnet area which has yielded in excess of 5 million ounces of gold. One objective of our planned exploration will be to better understand the geology at Ernest Giles which the Company believes is very similar to Mt Magnet.
The Yilgarn greenstones also contain both disseminated and massive nickel-sulphide mineralization.
The Carnegie target in the Ernest Giles project area resembles both the geophysical signature and size of Sirius ‘ Nova nickel deposit.
The Nova deposit hosts 10.2Mt at 2.4% Ni, 1.0% Cu & 0.08% Co for 242,000 tonnes Ni, 100,000 tonnes Cu & 7,700 tonnes Co based on a 0.6% nickel equivalent cut-off.
24 line kilometers of MMI sampling has been conducted over this Ni target, with results leading to a drill target. Drilling commenced in Q2 2015 intersecting mafic intrusive rocks from 286m below the surface to end of hole at 300m. These rocks displayed very strong heamatite and magnetite alteration, supporting the presence of a mafic intrusive body prospective for nickel sulphides. Analytical results highlight the prospectivity, with elevated As and Pb to 18ppm and 40ppm, respectively, at end of hole.
Greatland’s Carnegie target (left) & Sirius’ Nova deposit (right) to same scale
The project area covers two buried Archean greenstone belts, part of the Yilgarn Craton. The Archean basement is recognised to be part of the far eastern Yilgarn Craton. The eastern Yilgarn region contains the Wiluna, Leonora, Kalgoorlie, St Ives, and Norseman gold camps and the ‘world-class’ nickel sulphide deposits of Mt Keith, Leinster, and Kambalda.
At Ernest Giles, the locations of the Archean greenstone belts have been interpreted from aeromagnetic data collected by the Australian government and Western Mining Corporation (WMC).
These aeromagnetic images clearly show the presence of linear, strongly magnetic lithologies within the project tenements. The Archean greenstone sequence is covered by approximately 10m of recent desert sands along with +50m of fine grained Proterozoic sediments. Modern geophysics and geochemistry allows us to ‘see’ through the cover sequences to define drill targets.
Similar Archean stratigraphy is seen at Mt Magnet, 600km to the west. Gold deposits at Mt Magnet have yielded in excess of 5 million ounces of gold.
The Tropicana gold resource, 250km south of Ernest Giles, currently stands at over 5 million ounces of gold and this discovery has been made beneath desert sands in the order of 20 to 40 metres thick.