Mt Aubrey epithermal gold-silver project (100% Godolphin)
Mt Aubrey is located approximately 40 km northeast of Parkes and 30 km southeast of Yeoval and consists of one tenement (EL8543) of around 194 km² and is prospective for epithermal gold-silver and porphyry gold-copper-molybdenum deposits.
The project has an existing resource of 62k ounces of gold (See Godolphin Prospectus, 29 October 2019).
At the southern edge of the tenement there are three backfilled open pits that were mined by BHP in the early 1990s. It is reported that around 100,000 tonnes at 3.0 g/t Au were mined (Ostrowski M., 2019b) from an epithermal vein system. The tenement is also prospective for other deposit types, including porphyry copper-molybdenum, but only a few other minor historical workings are recorded.
The dominant rock types in the area are felsic intrusives, silicic to intermediate volcanics and minor sediments. There is an extensive sheeting of Tertiary and Quaternary alluvials over the tenement, especially over the southern and central portions.
Comprehensive stream sediment sampling has been carried out over the whole tenement. Other exploration activities include; surface mapping, geophysics and drilling, with the drilling mainly centred around the backfilled BHP pits.
Godolphin’s Mt Aubrey Project Phase 1 drill programme commenced in late January 2020 with the drilling of 14 RC drill holes for a total of 1,734 metres (GRL ASX announcement 20 April 2020). All drill holes intersected epithermal goldstyle veins and alteration, and the majority of drill holes reported elevated gold values, and five holes returned greater than 1 g/t Au over broad intervals. There were two standout holes: MAGRC0008 intersected a 22-meter-wide mineralised envelope from 22m below surface (including 6m at 7.21 g/t from 30m down hole) and MAGRC0011 intersected 28m @ 0.92 g/t Au from 60m (including 16m @ 1.1 g/t Au from 72m).
A Phase 2 drill programme commenced in August 2020. Preparation for this drill programme included the processing of data from the Phase 1 programme, field geological mapping, re-interpretation of results from an Induced Polarisation (IP) survey undertaken by previous tenement holder YTC in 2011, and the completion of a ground-magnetic survey. This work helped define drill targets around the historically mined pits. Drilling results received confirm that the mineralised quartz veins extend for more than 350 metres east of the main historical pit, which was mined by BHP in the early 1990s. Broad zones of gold mineralisation were intersected which correlate with the quartz veins intersected. The best assay results received were in drill hole MAGRC016 which intersected multiple zones of 8m @ 0.60g/t gold from 56m, 2m @ 1.22g/t gold from 84m and 2m @ 1.01g/t gold from 96m. (see Figure 5) MAGRC015 and MAGRC017 intersected broad low grade intersections of 10m @ 0.36g/t gold from 24m, and 12m @ 0.41g/t gold from 28m respectively. The mineralised veins intersected east of the main pit remain open along strike. Drill holes targeting geophysical and soil anomalies south-west of the historical pits failed to intersect any significant gold mineralisation.
EL8532 is located approximately 70 km northwest of Orange, centred on the locality of Baldry (Figure 1). Renshaw McGirr Way, which is a sealed road running from Yeoval to Parkes, runs through the centre of the tenement. The tenement covers an area of approximately 194 km².
This project has only minor historical workings (there are gold workings at Blue Hills (Figure 3) and there are references to other workings from the 1880s around Mt Aubrey). Recent activity did include BHP in 1990 mining three shallow oxide pits at Mt Aubrey, producing around 100,000 tonnes of ore at around 3.0 g/t Au. The deposit was based on an epithermal vein system.
The north to north-eastern part of the project area is dominated by the Yennora and Kynura granites. There are also small outcrops of the Cuga Burga mafic volcanics throughout and in the southern area the Dulladerry Volcanics.
The north-eastern corner of the tenement is crossed by a series of northwest trending faults, which appear to slightly offset the stratigraphy.
A west-northwest orientation of the Mt Aubrey deposit is thought to be an en-echelon array partly controlled by the location of major north trending regional structures.
The Mt Aubrey deposit, mined by BHP, is within an approximately 6 km long east-west trending vein system (Figure 2). Quartz vein textures and fluid inclusion studies indicate an epithermal type deposit (Ostrowski M., 2019a).
Surface mapping and drilling indicates that the Mt Aubrey vein system pinches, swells and bifurcates along strike and it is postulated that the vein system has preferentially developed within the more brittle and chemically favourable amygdaloidal basalts rather than the other surrounding felsic rocks.
A Mineral Resource Estimate for Mt Aubrey was completed in August 2019 (Ardea Resources Ltd, 2019a). The Mineral Resource Estimate was reported using a number of gold cut-off grades as tabulated in Table 1 and all Resources were classified as Inferred. A ≥0.5 g/t Au cu-off was used as a base case.
|Category||Cut-off (Au g/t)||Tonnes (Kt)||Au (g/t)||Contained Au (oz)|
Tonnages are rounded to the closest one hundred thousand and gold to the second decimal place.
Ardea completed some ground-based activities including; general reconnaissance, GPR, rock chip sampling and auger drilling. The soil auger programs were completed along strike from the Mt Aubrey deposit and at the Emu Swamp prospect. The Mt Aubrey program returned anomalous results at both strike extensions with results up to 103 ppb Au. The Emu Swamp program returned anomalous molybdenum values which were also associated with anomalous rock chip samples.
There is a high potential to increase the current Mineral Resource for Mt Aubrey as most of the current drilling is restricted to around 50 m below surface and also restricted along strike. Drilling by Ardea will initially target down plunge areas of shoots that have already been identified.
Godolphin is planning to undertake an RC drilling program in and around the Mt Aubrey deposit and use this to update the geological model and the current Mineral Resource Estimate. This may also lead to defining further drilling activities.
Portions of the tenement will also be soil sampled – mainly concentrating in the areas of Blue Hill, Mt Aubrey South, Far North and East, as well as Emu Swamp.
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