Tanami Region (Gold)
The Tanami Project, located in the Kimberley region of WA, occupies approximately 900km2. It is positioned approximately 1,500km northeast of Perth, 220km south-southeast of Halls Creek in the Tanami desert, adjacent with the Northern Territory (NT) border.
While a remote area, the Tanami Road provides access to the project from Halls Creek, with station and exploration tracks providing access to prospects. Currently under care and maintenance, the Coyote Gold Mine is the region’s most significant modern mining project. Northern Star Resources Limited own the Coyote Gold Mine, the village and operations are located just 10km from the project area.
Structurally controlled orogenic Gold deposits host the majority of Gold mineralisation in the Granite – Tanami Orogen. Identifying areas of thrusting, anticlinal stacks, crustal penetrating shear zones and associated structures is considered key to discovering gold in the region. Historically mineralisation has been identified in the Killi Killi Formation, and Stubbins Formation (equivalent to Dead Bullock Formation in the Northern Territory), both metamorphosed sedimentary sequences of the Tanami Group. These formations along with intrusive granitoids dominate the geology underlying PVW tenements. The Lewis Granite, part of the Granites Supersuite, is a significant geological feature and itself represents a prospective host for Au, Cu and Sn mineralisation.
PVW are exploring for Gold in the Tanami, the potential for other commodities including REE’s, Sn and PGE’s adds to the prospectivity of the large tenement holding.
Tanami Project and tenement location
The bedrock geology of the Project area is dominated by the Tanami Group sequence of Lower Proterozoic folded metasediments. The Killi Killi Formation overlies the Stubbins Formation, a sequence of metasediments and minor volcanics which in turn overlies Archaean basement. The Killi Killi Formation is a sequence of turbidites, predominantly sandstones, greywackes and shales metamorphosed to greenschist grade. Because of weathering and their composition, the rocks seldom outcrop and usually only do so as lateritised low ridges with quartz veining.
The structural grain of the district is west-northwest reflecting the major element of faulting, the Tanami Structural Corridor, which extends from the west into the Tanami and Granites/Callie goldfields of NT. Near the Coyote mine it is manifested in the large quartz reef referred to as the Tanami Fault reflecting a regional fracture.
A number of granites intrude the Lower Proterozoic sediments, predominantly comprise ‘I- type’ biotite ± hornblende monzogranite and granodiorite. Several granite intrusions occupy diapiric structures within the Killi Killi Formation. The Lewis Granite, a large granite pluton was drilled by Orion and found to be a variably magnetic K-feldspar – biotite granite with subdued geochemical character.
Strongly magnetic bodies within stratigraphy have not been effectively targeted in historical exploration efforts. They may have been intruded during rifting phases, folded with stratigraphy during orogenesis. Their origin is uncertain and will be tested during exploration activities.
Regional geology of the Tanami Project
The early explorer Talbot passed through the area in 1909 and recorded the presence of gold at several locations in the Tanami. The project area was first explored commercially by Queensland Mines Ltd in 1969 as a uranium project that found small quantities of secondary uranium. However, a small suite of samples was analysed for yttrium and REE. Petrology was also done, and this work first confirmed the existence of crystalline xenotime mineralisation (Premoli & Day, 1970). Ongoing since the 1950’s, Geoscience Australia, GSWA and GSNT have undertaken geological mapping, compiled total magnetic intensity, bouguer gravity and radiometric images, and undertaken numerous research initiatives throughout the Tanami region.
Modern exploration in the project area has been dominated by the “Western Tanami Project” commenced by Shell in 1992 and continuing for 22 years through a series of tenements, deals and various joint ventures involving 8 other companies concluding with Tanami Gold NL, as follows:
- 1992 – 1995 Shell Company of Australia Ltd
- 1993 – 1996 Acacia Resources Ltd
- 1994 – 1995 Zapopan
- 1995 – 1996 Cove Mining NL
- 1994 – 1996 Zapopan NL
- 1994 – 2000 Tanami Gold NL
- 1995 – 2000 AngloGold (Acacia Resources Ltd)
- 2000 – 2003 AngloGold Australia
- 2000 – 2004 Barrick Gold of Australia Ltd
- 2004 – 2014 Tanami Gold NL
Most recent exploration efforts in 2012 involved surface geochemical rock chip sampling at the Killi Killi East prospect, and RC drilling program at both Killi Killi East and Killi Killi West. Rock chip sampling of conglomerate lenses at Killi Killi East returned encouraging REE assays, delineated a strike length of more than 1km of REE anomalism with totaled REE assays averaging 4,730ppm TREE. While the drill REE assays were disappointing, gold mineralisation was intersected in 3 holes, with a best intercept of 16m @ 2.48g/t Au from 60m in KKO-116. In 2013 mapping investigated gold mineralisation in KKO-116 confirming drilling had intersected an outcropping shear zone.
The bulk of PVW’s efforts have been on integrating the regional data and reprocessing GSWA seismic data with a focus on interpretation of shallow data. The work to date has significantly improved the understanding of major structures and where they provide possible drill targets. In conjunction with further geophysical data collection and interpretation, field work will be focused on follow up drilling of existing gold anomalies. Detailed geophysics will be ongoing and essential to efficiently target within the large tenement package.
Exploration Gaps – Discovery Potential
The Tanami region which incorporates PVW’s Tanami Project has received around 22 years of modern exploration, in those 22 years 9 companies have explored for various commodities. Key points to consider following a short history of exploration:
- Exploration success has been limited to areas of outcropping or sub-cropping mineralisation.
- Given there is a lack of outcrop in the Tanami, the effective application of surface exploration is limited.
- This lack of outcrop led early explorers to apply shallow drilling techniques to investigate the near surface geochemistry.
- Importantly the depth of regolith (transported and in situ) is generally unknown, the transported profile is complicated, and without testing in-situ material below the transported cover the effectiveness of shallow drilling is unknown.
- Most of the project has been sparsely and superficially explored with very shallow <6m deep RAB or Vacuum drilling (Figure 2).
Exploration success has been hampered by some significant geological obstacles, these are technical challenges that can be overcome and include:
- A regional lack of outcrop or consistent surface sample medium, highlighting the need for detailed geophysics, and where applicable drilling to bedrock.
- There is a lack in variation of outcrop and a lack of bedrock intersected in the regional drilling. The preferentially mineralised units have variable geochemistry relative to their hosting stratigraphy. Finding the variations in the right structural setting is essential to finding further mineralisation, requiring deeper thinking to target and deeper drilling to test targets.
- Downhole geochemistry is lacking in the region. While geophysics will be essential to targeting, geochemistry will be essential to evolution of the targets, hence the need for routine downhole geochemistry to distinguish preferred host lithologies.
Understanding these obstacles, provides PVW with an opportunity, and overcoming the technical challenges improves the likelihood of a discovery.
Tanami Project and Drill Hole Depth Analysis. Note Orange Drill Holes are <6m depth.
Planned Exploration Activities
Exploration activities aim to refine key target areas and generate new targets. Initial field work will follow Heritage and Cultural approvals that will be completed with representatives of the traditional owners, the Tjurabalan. All follow up activities will also require communication and approval with the traditional owners following our Heritage Agreement.
Proposed exploration activities will include:
- Acquisition of 50m line spaced airborne geophysical data.
- Southern Geoscience Consultants to undertake interpretation and detailed litho-structural interpretation and targeting.
- Integration of available Seismic data.
- Integration of available Gravity data.
- Field confirmation of targets, including the Killi Killi West drilling results and other targets resulting from litho-structural interpretation.
- Drilling along strike from Killi Killi West.
- Drilling of other targets.
- Application to EIS incentive for Diamond drilling of magnetically anomalous units.
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