Bardoc Tectonic Zone Gold Project ARL 100%
“The majority of the prospective basement rocks within Ardea’s large, strategic tenement package in the Eastern Goldfields of Western Australia are concealed by surface cover and lake clays. However, detailed project assessment has demonstrated that fertile major gold-controlling structures pass through Ardea’s tenements. To intersect significant gold mineralisation in the initial RC drill program at the Aphrodite North area demonstrates proof of concept and is a credit to the Exploration Team. This result is especially exciting as it is only one of many targets defined within Ardea’s extensive BTZ gold target inventory. On the basis of the initial results, a 2,600m follow up RC program has been designed, aiming to commence a drill out of the target zone to further define the gold mineralisation grade tenor and geometry.”
— Ardea’s Managing Director, Andrew Penkethman
The Bardoc Tectonic Zone (BTZ) is a major, gold-fertile, crustal-scale structure that transects the Kalgoorlie Terrane of the Eastern Goldfields. The regional shear/fault system strikes from Paddington in the south to northwest of Ghost Rocks in the north and extends over an approximate 125km strike length, of which some 65km occurs within Ardea tenure. Ardea’s GNCP is unique among the world’s lateritic nickel-cobalt deposits in that it has developed on ultramafic rocks that are within and are a part of a major, crustal-scale gold-mineralised structure being the BTZ.
The BTZ typically dips moderately to the west, hosting the Paddington, Goongarrie, Comet Vale, Yunndaga, Menzies, Lady Irene and Lady Isobel historic gold mining centres. To the south, the BTZ is contiguous with the Boulder-Lefroy Fault, the host to the Kalgoorlie Golden Mile, New Celebration and St Ives gold mining centres and is considered to be part of a single gold-fertile crustal structural system stretching from St Ives in the south to Ghost Rocks in the north.
The Aphrodite North area is located approximately 80km north of the City of Kalgoorlie-Boulder and 6km north along strike of the 1.7Moz Aphrodite gold deposit (BDC, ASX release 25 June 2020). Aphrodite North is entirely covered by transported material and thus exhibits no surface anomalism. The target structure extends in a north-northwest orientation throughout Ardea’s Mining Lease, M29/426.
In July 2020 a 7 hole program of RC drilling was undertaken to test target from previous airfare drilling.
- RC drilling at Aphrodite North within the Bardoc Tectonic Zone (BTZ) has intercepted significant gold mineralisation in newly-defined mineralised lodes.
- AANR0001: 6m at 3.60g/t Au from 44m from the West 2 Lode
including 2m at 9.99g/t Au from 44m
and 8m at 4.94g/t Au from 172m to 180m EOH in Main Lode
including 4m at 9.42g/t Au from 172m
- AANR0002: 10m at 1.52g/t Au from 76m from the East 2 Lode
and 2m at 0.63g/t Au from 226m to 228m EOH from Main Lode
- AANR0004: 12m at 0.73g/t Au from 160m (lode to be determined)
including 2m at 2.39g/t Au from 162m
- AANR0006: 4m at 1.01g/t Au from 140m (lode to be determined)
- AANR0001: 6m at 3.60g/t Au from 44m from the West 2 Lode
- Holes AANR0001 and AANR0002 were stopped whilst drilling in mineralised Main Lode due to drilling difficulties associated with wet surface clays.
- Gold mineralisation intercepted in fresh rock occurs as multiple discrete lodes:
- over +700m NNW strike length;
- over a +170m east-west width around the contact of a western dolerite with eastern andesitic volcaniclastics and shale; and
- strong quartz-pyrite-calcite veining is visually distinct.
- A 2,600m follow up RC drilling program has been approved.
Grafter gold prospect
The Grafter gold prospect is an underexplored area, covering 3.7 x 1.5 km in the south-eastern GNCP, located approximately 65km north northwest of the City of Kalgoorlie Boulder. Around 80% of the area is covered by transported and laterite cover and has been interpreted from a combination of field work and desk top studies as a deformed mafic hangingwall sequence highly prone to gold mineralisation. As the area was previously held by prospectors, there has been no modern systematic exploration. The Ardea exploration team have identified similar structural relationships to BTZ-BLF “structure kinks” as documented at the Paddington, Kalgoorlie and New Celebration gold camps.
A modest “toe in the water” first-pass RC exploration program has commenced at Grafter to test three different types of target (A / Lady Charlotte, B and C), with the knowledge gained to be used to continue to refine the exploration targeting approach on concealed BTZ gold targets. Two RC holes were completed at Lady Charlotte in July 2020. The initial RC result from ABFR0286, 8m at 6.57g/t Au from 24m, is an excellent start to the first round of gold exploration drilling at Grafter. This intercept is interpreted to represent high grade supergene mineralisation, with the primary lode position and orientation to be defined by follow-up RC drilling.
The prospect is located immediately south of an extensive plain of transported cover. The initial Grafter drilling was selected at Lady Charlotte on the expectation of shallower transported cover, thus allowing a more cost-effective window in on the sub-surface geology. On the regional scale, it is very interesting that on drill-testing, the first exposures for several kilometres are mineralised. Follow-up exploration drilling is planned to recommence in late September 2020.
Big Four gold prospect
The Big Four gold prospect is located within the BTZ south of Goongarrie and offers an exceptional gold exploration opportunity for Ardea with high gold grades apparent in shallow geological settings. Limited historic mining around the 1920s to 1930s recovered 571.5t of ore for 10.53kg Au (~339oz Au), at an average grade of 18.4g/t Au. This gold occurrence cropped out at surface so was discovered by prospectors. Most of Ardea’s tenure is covered by shallow alluvial cover and/or the development of a laterite profile which obscures the underlying gold potential.
The most recent Ardea drill results from the Big Four area, as well as reassessed historic data, shows that strong, laterally extensive gold anomalism is present beneath the full 20km strike length of the nickel-cobalt orebodies of the GNCP. The exceptional thickness and grade of the GNCP laterite is interpreted to be directly attributable to deep and intense weathering along BTZ bedrock shear structures, particularly at the eastern contact of the Walter Williams Formation (WWF) laterite host rock with the stratigraphically overlying Siberia Komatiite.
Infill and extensional drilling completed by Ardea in January 2020 and historic data collated by the Company has enabled estimation of an Inferred Mineral Resource being 178kt at 2.7g/t gold for 15,300oz gold (0.5g/t Au cut off).
This result provides proof of concept of the gold mineralisation potential of the BTZ within Ardea’s GNCP, which elsewhere is concealed by Quaternary sediments and the overprinting nickel laterite profile.
Metallurgical composites have been prepared from the RC drill samples and are currently undergoing metallurgical testwork, confirming gravity and cyanide leach recoverable gold (no refractory gold identified). Once completed, the total gold recoveries will be available to advance discussions on monetising the Big Four Gold deposit.
Ghost Rocks gold prospect
Three main prospect areas have been defined at Ghost Rocks, being the Lady Isobel gold prospect, the Twelve Mile base metal prospect and Ghost Rocks Southeast gold and nickel prospect. Soil auger drilling, rock chip and geological mapping data have been used to generate drill targets around historic gold workings at Lady Isobel. A first phase drilling program targeting quartz veins subject to historic mining is planned to be completed in Q1, 2020.
Windanya gold prospect
Windanya is a historical gold mining centre that was operational in the 1900s. It is hosted within the BTZ, 20km south of the GNCP Scotia Dam nickel-cobalt deposit. Historic gold workings are evident on the tenement and extend as a corridor to other workings to the north and south of the Ardea tenement. The trend of the mineralised zone appears to be approximately 330˚.
Gold mineralisation appears to be focused on a marker unit designated by the Geological Survey of WA as the Big Dick Basalt and the overlying Mt Pleasant Gabbro. The location of the mineralisation, in the hangingwall of the Siberia Komatiite, is analogous to the New Boddington gold mining centre at Goongarrie, and to parts of the Ardea Zeus prospect at Big Four, which both trend around 330˚. Like these prospects, the mineralisation may well be stretched along sheared stratigraphic contacts, but also localised on minor cross-cutting structures.
Compilation and interpretation of historic data continues with records sourced for the Half Mile Reef located near the centre of Ardea’s Windanya tenure, indicating that between 1897 and 1906, 23,480 tonnes of ore were mined from an underground operation, producing 12,993 ounces of gold. This indicates a recovered gold grade of 17.2 g/t.