The Tobruk and Monza JV projects are both with Newmont Australia and in total covers an area of around 6,820 square kilometres of exploration licences and applications in the Tanami Region of the Northern Territory. The Tobruk JV was signed in May 2019 with Newmont sole funding exploration activities on the project to potentially earn up to a 70% stake in the project. The Monza JV was signed in November 2021 with Newmont able to earn a 51% stake in the project through funding exploration and will then be able to increase this to 70% through a decision to mine.
The Tobruk Project covers the prospective Tanami group rocks that host Newmont Goldcorp’s Callie Gold deposit and several smaller deposits including Groundrush and Titania-Oberon. The Project’s potential for the discovery of a significant new gold deposit is further enhanced by having an analogous structural setting to known Tanami deposits including tightly folded stratigraphy, Trans-Tanami parallel faults and drill-defined anomalous geochemistry positioned on the margins of magnetic features.
The Project includes exploration licences and applications along strike of, and containing structures parallel to, the Trans-Tanami Fault trend. This trend is the regional control of major gold deposits in the area, including Newmont Mining’s 14.2 million ounce Callie Gold Mine (1Schmeider et al 2018).
Previous exploration has primarily been soil sampling and patchy reconnaissance drilling with 10 of the 18 tenements in the Project having no drilling in the last 20 years.
The Project hosts key targets along strike or parallel to the Trans-Tanami Fault trend which have seen limited or no previous exploration. Positive results have been received from previous drilling completed at the Dune Prospect, located 1.5 kilometres to the south of Newmont’s Oberon Deposit
Previous RC drilling within the Project area has defined significant gold anomalies in oxide at Dune over a strike length of 1.4 kilometres. Within this area results included (ASX: 22 Jan 2019, 19 Aug 2019 & 28 Nov 2019):
- 2 metres @ 12.0 g/t Au from 105 metres (EUR0006)
- 8 metres @ 1.9 g/t Au from 94 metres (EUR0003)
- 36 metres @ 0.6 g/t Au from 104 metres, including 20 metres @ 0.95 g/t Au from 105 metres (EUR0010)
- 18 metres @ 0.4 g/t Au from 126 metres, including 2 metres @ 1.24 g/t Au from 126 metres (EUR0019)
- 10 metres @ 0.3 g/t Au from 146 metres (EUR0021).
1 S. Schmeider, S. Perazzo, L. Griesel, and C. Robinson 2018. Tanami Operations, Callie mine: Multiple new discoveries supporting transformational growth in a mature mining camp, Abstract and Presentation in ‘Annual Geoscience Exploration Seminar (AGES) 2018. Record of Abstracts’. Northern Territory Geological Survey, Record 2018
The Newmont exploration team are actively exploring the JV tenements with a first phase soil geochemical sampling campaign planned in the short term. Newmont have been active on these projects now regional exploration can restart after the Covid-19 restrictions from the past few years.
Geology and Mineralisation
The Proterozoic Granites-Tanami Inlier is located about 600km NW of Alice Springs, in the Northern Territory and forms part of the broader Northern Australian Orogenic Province (2Plumb, 1990). The Inlier underlies, and is bounded by, the Palaeozoic Canning, Neoproterozoic Wiso and Paleoproterozoic Victoria River Basins to the west, east and north respectively. The Arunta Complex lies to the south and may represent a continuation of the Halls Creek Orogen in Western Australia (3Hendrickx, et al, 2000). To the north-west, clastic sediments of the Middle Proterozoic Birrindudu Basin overlie and separate the Inlier from the similar age rocks in the Halls Creek Province.
The oldest rocks of the Tanami region belong to the Billabong Complex, a suite of Archaean age gneiss and schist. This is unconformably overlain by the basal Proterozoic sequence known as the MacFarlanes Peak Group dominated by mafic volcanic and volcanoclastic rocks suggestive of a rift setting. The Macfarlanes Peak Group has a maximum age of deposition of 1880 Ma. This is followed by a thick, possibly dis-conformable succession of clastic sediments making up the Tanami Group representative of a passive margin sequence. (3Hendrickx et al, 2000). The Tanami Mine Group is subdivided into a thin basal meta-quartzite, the lower Tanami Group (Dead Bullock Formation) made up of carbonaceous siltstone, BIF’s and calc-silicates and an upper sequence of turbidites (Killi Killi Formation). A suite of pre-to syn-deformation dolerites and gabbros are found intruding both the MacFarlane Peak and Tanami Groups. Complex, polyphase deformation during the Tanami Orogeny (1845-1835 Ma) has affected the entire Inlier (4Vandenberg et al., 2001). Peak regional metamorphism during the Tanami Orogeny reached amphibolite facies, but is more generally greenschist facies through the Inlier. Contact metamorphic aureoles are well developed at the margins of granite plutons emplaced throughout deformation. Formation of molasse during the
Tanami Orogeny occupies a small syn-orogenic sub-basin to the west of the inlier (Pargee Sandstone). A period of crustal extension (≈1830Ma) followed the Tanami Event, this resulted in the deposition of basalt and turbiditic volcanics in an inferred failed rift (Mt Charles formation) along with high level granite intrusion and felsic volcanism from ≈1830-1800Ma (5Dean, 2001). At least three suites of granitic intrusives and two volcanic complexes are present. The last intrusion of (undeformed) granite occurred at around 1805 – 1790Ma, with intrusion of The Granites Suite (Dean, 2001). Residual hills of gently folded Birrindudu Group siliciclastics unconformably overlie early Proterozoic lithologies and provide platform cover sequences. Younger flatlying Cambrian Antrim Plateau Basalts are also preserved in areas protected from erosional stripping. Tertiary drainage channels, now completely filled with alluvial sediment, lacustrine clays and calcrete are a major feature of the region. Some drainage profiles exceed 10 km wide, 100m depth, presenting a formidable barrier to mineral exploration. A desert terrain comprising transported and residual colluvial cover sediments and aeolian sand blanket a large portion of the Inlier, with an estimated outcrop exposure of less than 10% of the early Proterozoic lithological units. Gold mineralisation within the Tanami is dominantly hosted by the Tanami Group and Mt Charles Formation, though mineralisation has been recorded in all Proterozoic units older than the Birrindudu Group cover sequences. Owing to their more resistant nature, only the cherts and iron-formations and associated interbedded graphitic schists tend to outcrop above the sand plain.
2 Plumb, 1990 Halls Creek Province and The Granites-Tanami Inlier – regional geology and mineralisation, in Geology of the Mineral Deposits of Australia and Papua New Guinea (Ed F.E. Hughes) pp 681-695 (The Australasian Institute of Mining and Metallurgy: Melbourne).
3 Hendrickx, M., Slater., K., Crispe, A., Dean, A., Vandenberg, L. & Smith, J. 2000. Palaeoproterozoic stratigraphy of the Tanami Region: regional correlations and relation to mineralization- preliminary results. NT Geological Survey Record GS2 2000-13.
4 Vandenberg, L.C., Hendrickx, M.A. & Crispe, A.J., 2001. Structural geology of the Tanami region. NT Geological Survey Record 2001/4.
5 Dean, A.A., 2001. Igneous rocks of the Tanami Region. NTGS Record 2001-003