Altair Copper-Zinc Prospect
The Altair Copper Prospect is interpreted to be Volcanic-Hosted Massive Sulphide (VHMS) style copper mineralisation associated with black shales and intermediate volcanics (Figure 1). The Company interprets the geological setting of the mineralisation at Altair to be that of a VHMS / SEDEX environment. Evidence for this interpretation includes:
- Restrictive black shale depositional environment, overlying an interpreted volcanic exhalative chert horizon;
- Extensive chlorite alteration and pyrite development in footwall intermediate volcanics;
- Evidence for mineralisation to have formed pre-deformation, and possibly syn-deposition; and
- Anomalous geochemical pathfinder elements characteristic of VHMS / SEDEX systems.
Volcanic-associated mineral deposits tend to occur in district-scale “camps”, with individual deposits occurring in favourable stratigraphic positions over many kilometres. In this respect, the Company considers the Teutonic Bore group of deposits, located approximately 200km southeast of Altair, to be a relevant analogy. Teutonic Bore contains three former or operating mines (Teutonic Bore, Bentley, Jaguar), that host current Resources totalling 6.5Mt @ 5.6% Zn, 0.9% Cu, 85g/t Ag and 0.4g/t Au (refer to Independence Group NL announcement dated 23 October 2017).
Limited drilling in the 1990’s by Goldfields Exploration intersected broad zones of copper mineralisation at Altair, including the following assay results:
- 44m @ 1.2% Cu from 56m (ALAC005);
- 24m @ 1.0% Cu from 64m (ALRC007);
- 20m @ 1.1% Cu from 52m (ALRC002); and
- 20m @ 0.9% Cu from 64m (ALRC006).
In 2018 and 2019 Horizon Gold Limited drilled 23 RC and diamond holes for 7,269m beneath the Goldfields Exploration intercepts returning the following significant zinc-copper intercepts from the base of a black shale sequence (refer to Horizon Gold Limited ASX Announcements dated 13 February 2019, 26 March 2019 and 2 April 2019). Significant assay results included:
- 78.0m @ 1.90% Zn and 0.32% Cu from 288.0m incl. 14.0m @ 2.34% Zn and 0.51% Cu from 342.0m (ALDD014)
- 62.6m @ 2.45% Zn and 0.42% Cu from 262.0m incl. 19.0m @ 3.09% Zn and 0.53% Cu from 297.0m (ALDD019)
- 38.0m @ 1.89% Zn and 0.64% Cu from 97.0m incl. 21.0m @ 2.47% Zn and 0.55% Cu from 106.0m (ALDD007)
- 36.0m @ 2.58% Zn and 0.41% Cu from 344.0m incl. 21.0m @ 3.10% Zn and 0.55% Cu from 358.0m (ALDD017)
- 32.0m @ 1.90% Zn and 0.37% Cu from 154.0m incl. 14.3m @ 2.59% Zn and 0.55% Cu from 166.0m (ALDD009)
- 35.6m @ 2.44% Zn and 0.43% Cu from 120.0m incl. 19.0m @ 3.42% Zn and 0.54% Cu from 129.0m (ALDD016)
- 30.0m @ 1.89% Zn and 0.34% Cu from 135.0m incl. 13.0m @ 2.30% Zn and 0.43% Cu from 150.0m (ALDD022)
- 26.1m @ 1.93% Zn and 0.25% Cu from 244.0m and 43.5m @ 2.96% Zn and 0.50% Cu from 274.2m (ALDD012)
- 18.0m @ 2.41% Zn and 0.52% Cu from 97.0m incl. 8.0m @ 3.00 % Zn and 0.88% Cu from 107.0m (ALDD008)
- 15.2m @ 2.33% Zn and 0.27% Cu from 136.0m incl. 5.4m @ 3.84% Zn and 0.23% Cu from 137.0m (ALDD011)
The Altair primary zinc-copper mineralisation forms a thick, steeply south dipping, contiguous lens of mineralisation that plunges to the southeast and remains open at depth in this direction where additional drilling is planned.
The extensive geophysical data set (including airborne and ground EM, is being reviewed and re-modelled with the aim of testing EM conductors and gravity highs at depth to the south of Altair and along strike to the north at the Mensa Prospect.
Figure 1: Geological plan of the central Gum Creek project area showing the location of Altair and Mensa Prospects
Figure 2: Altair Prospect – drill hole location plan
Figure 3: Altair Prospect – long section (7006480N)
Figure 4: Altair Prospect – long section (7006420N)
Figure 5: Altair Prospect – long section (7006360N)
Figure 6: Altair Prospect – cross section (731350E)
It is important to note that base-metal geochemistry at Altair (and potentially more regionally) is strongly depleted to around 50m depth. As can be seen in Figures 3 to 5, the supergene copper mineralisation occurs below 50m depth, and was not intersected in the initial vertical RAB and air-core holes drilled in the early 1990’s. This suggests that the historical wide-spaced and shallow drilling conducted in the Gum Creek Greenstone Belt may not have been an effective test for this style of mineralisation.
Regional mapping and geophysical interpretation at Gum Creek suggests the target stratigraphy hosting the Altair prospect may extend at least 5km to the north to the Mensa Prospect (Figure 1). At Mensa, shallow drilling in the 1990’s by previous explorers intersected anomalous zinc mineralisation in a similar geological setting as Altair, including the following intercept calculated using a 0.1% Zn lower cut-off*:
- 6m @ 0.22% Zn from 50.0m in GMRC001
Additional drilling is planned for the Mensa Prospect.
*Refer to the following open-file historical company technical reports submitted to the WA Department of Mines, Industry Regulation and Safety (DMIRS):
- WA Exploration Services Pty Ltd, Annual Report E53/665, Gum Creek Project, 1998. GSWA open-file report A54645