DGO’s Mallina tenements adjoin De Grey Mining’s Mallina Gold Project and share a similar geological and structural setting to De Grey’s tenements which host substantial structurally controlled gold resources and the significant Hemi discovery.
The DGO tenement package incorporates over 30km’s of strike length of a major ENE-trending structure that parallels the Mallina Shear Zone (MSZ). Gold occurrences in the region are commonly associated with intrusives and anticlinal axes. Gold nugget discovery and soil samples up to 1.2g/t at Scottie Well, and Coziron drilling results at Top Camp, supports a target over 16km strike length at the intersection of anticlines and the ENE trending structure.
Yerrida is located 25 to 100 kilometres from Sandfire Resources’ DeGrussa operations. Detailed data review and analysis has confirmed that the Yerrida Basin represents a favourable, intra-cratonic, restricted basin setting of the right age, prospective for stratiform sediment-hosted copper (SSH Cu) deposits analogous to the world-class Zambian Copper Belt (ZCB).
Targets for ZCB copper mineralisation are associated with the reduced carbonaceous and pyritic siltstones of the Johnson Cairn Formation immediately overlying the oxidised clastic units of the Juderina Formation. The carbonaceous shales and siltstones of the Maraloou Formation overling the basal Juderina Formation are also targets.
An EM survey over 20km Au-Cu-Zn soil anomaly in 2019 defined seven priority EM conductors within the Killara and Doolgunna Formations, the stratigraphic equivalents of the formations in the Bryah Basin that hosts the DeGrussa copper/gold deposit. A further eight priority targets were identified representing conductors within the targeted Killara, Doolgunna and Johnson Cairn formations. One of the identified targets is 1.6 kilometres long and lies adjacent and parallel to a line of anomalous gold and copper soil geochemical results recorded by earlier explorers.? This high priority target occurs at the interpreted contact between the Johnson Cairn shale and the underlying Juderina sandstone formation, on-lapping a granite basement high. This setting has characteristics analogous to the environment and setting that hosts the Zambian Copper Belt deposits.
DGO’s Pernttty Lagoon tenements are located in the Eastern Gawler Craton, South Australia within the Stuart Shelf Copper-Gold Province which hosts BHP’s world class Olympic Dam copper-gold-uranium mine, and a number of other copper-gold deposits including Oz Minerals’ Prominent Hill and Carapateena. DGO’s tenements cover 1,146km2 over four granted exploration licences immediately to the east and south of the Mount Gunson copper deposits, approximately 120km northwest of Port Augusta.
DGO engaged the services of Dr Stuart Bull, an expert in Zambian Copper Belt deposits, to review the historic data and drill core in the Stuart Shelf. His analysis identified a +20km long transition zone between shallow water carbonates on a basement high (Woocalla Dolomite) and reduced basin shales (Tapley Hill shale) overlying an oxidised sandstone (Pandurra Formation). The Tapley Hill Formation is part of the Neoproterozoic Adelaide Rift Complex-Stuart Shelf succession and is the same age as the Katangan Supergroup which hosts the Zambian Copperbelt. The basin setting at Pernatty Lagoon has many similarities with the edges of the Katangan basin which hosts deposits such as Chambishi (124Mt @ 2.6% Cu).
The review identified significant copper in historic drillholes immediately east of DGO’s tenements at the Tapley Hill-Pandurra contact close to the interpreted transition zone such as 1.9m @ 1.7% Cu from 185m (hole PRL10/SAR5). On the western side of DGO tenements, chalcocite is present in an intersection of Woocalla Dolomite within drillhole PY4. These results highlight the lack of exploration within the interpreted transition zone and the potential for significant mineralisation.
DGO also completed a collaborative research project with the Centre for Ore Deposits and Earth Sciences (CODES) at the University of Tasmania which delineated a particularly strong Zambian Copper Belt (ZCB) style target masked by Pernatty Lagoon. The research program applied laser-based analysis of sedimentary pyrite in the Tapley Hill Formation to identify the presence of traces of indicator elements and isotopes providing vectors towards sediment-hosted copper mineralisation.
A cluster of historic drill holes approximately 5km to the east of Pernatty Lagoon, analysed by CODES show Pb isotope ratios, and elevated Ag, Cu, As and Ti in pyrite which supports the contention that a copper mineralised body could be present along the east dipping Tapley Hill-Padurra unconformity surface below and to the east of Pernatty Lagoon. In particular, analyses by CODES on samples from drillhole PN-06-03 suggest that it is proximal to a copper mineralised body.
Pernatty Lagoon is a shallow, compelling, and highly prospective copper target in a province where sedimentary copper potential has been largely ignored for the last 40 years and which warrants further work.
DGO’s Bryah tenements are prospective for sediment-hosted gold with the central tenement containing areas of known gold nugget occurrences adjacent to Judge’s Find. At Judge’s Find, surface mining for gold has occurred for some time, although the source of this alluvial gold is unknown. Gold mineralisation is thought to be controlled by thrust-fault bounded, anticlinal structures at the contact of the Juderina Sandstone and Johnson Cairn Formation black shales.
An EM survey in 2019 identified thirteen conductive anomalies, including nine along the axis of a regional anticlinal structure within the Juderina Formation.? Drilling of four high priority anomalies along strike from Judge’s Find nugget field occurred in March 2020.
DGO’s Black Flag tenements are approximately seven kilometres north-northwest of Horizon Minerals’ Teal Well open pit. This mine produced 21,800 ounces of gold at a grade of 3.2g/t. Mineral resources at Teal, Peyes Farm and Jacques Find total 4.25 million tonnes at 2.1g/t Au for 289,000 ounces (IRC Quarterly Activities Report 30 June 2019). The mineralisation is hosted in a series of semi-parallel shears within Black Flag felsic volcanics and sediments defining a +200 metre wide northwest trending, mineralised structural corridor which trends into First Au Limited’s tenements then onto DGO’s tenements to the north.
High grade gold mineralisation was discovered in 2018 by First Au at Gimlet immediately north of Teal Well. A mineral resource of 68,700 ounces at a grade of 3.3g/t Au has been established (FAU: ASX announcement 7 May 2019) and high-grade diamond core results including 32m at 4.9g/t Au from 93m have subsequently been reported (FAU: ASX announcement 28 May 2019).
Interpretation of regional airborne magnetic data shows that potential extensions of the north-northwest trending Teal-Gimlet structural corridor extend for six kilometres within DGO’s tenements. This structure was the target of recent drilling by DGO and resulted in intersections of:
Lake Randall is located 50km east of Gold Fields St Ives operation and immediately south of Silverlake Resources’ Mt Belches Mining Centre. DGO Holds 230km2 of untested, prospective terrain under lake and transported sediment cover.
Gold mineralisation at Mt Belches is hosted in Banded Iron Formation (BIF) units and is localised in anticlinal fold hinges and on the limbs of chevron folds within the Mount Belches area. DGO recently completed a ground gravity survey (results pending) to identify similar structural targets to those hosting the Mt Belches resources.
DGO’s Tom Price tenements cover a large, 70 km long regional anticlinal structure, with the Pyradie Formation outcropping in the central zone of the structure and interpreted to lie below younger units on the limbs. Previous exploration of the structure identified anomalous gold mineralization up to 2.8 g/t gold in rock chip samples of siliceous chert units assigned to the Pyradie Formation (IGO ASX announcement 28 July 2003).