LAKE JOHNSTON PROJECT
The Lake Johnston Project consists of Okapi’s 100% owned tenement E63/2039 and a joint venture with Lithium Australia NL (ASX: LIT) to earn 75% on tenement E63/1903. The tenements are located in the central Lake Johnston Greenstone Belt (Figure 1), approximately 450km east of Perth.
Based on a review of open file historical data Okapi applied for tenement E63/2039 to cover an interpreted structural target and coincident gold in soil anomaly. The tenement also contains the historical Maggie Hays Hill gold workings. These workings comprise two lines of SE-trending historical gold pits and shafts, hosted in sheared amphibolites and minor felsic units. They are among the few historical gold workings in the belt and have therefore been a focus for the limited previous gold exploration programmes. The priority target zone sits adjacent to the historical workings but has not yet been adequately drill tested (Figure 2).
Tenement E63/1903 is located at the southern end of the Lake Johnston Greenstone Belt in central Western Australia. The belt hosts the Mount Holland Gold Mine (Wesfarmers, ASX:WES) and Lake Johnston nickel mines (Poseidon Nickel, ASX:POS). The Project is located ~10km from the Maggie Hays and Emily Ann underground nickel mines and also the Windy Hill accommodation village owned by Poseidon Nickel (ASX:POS) (Figure 1).
Figure 1: Location of the Okapi’s tenements in southern Western Australia
Figure 2. Anomalous gold zone from open file data
The area has been the focus of nickel and lithium exploration with limited follow up on the gold potential.
At tenement E63/1903, Okapi has identified a high priority structural target from the magnetics, that is coincident with anomalous gold in a soil anomaly over a 10km strike length (Figures 1 and 2). Limited historical drilling near the main target area reported gold mineralisation, including LJPC004 (RC): 26-28m 2m @ 11.04 g/t gold and LJPC0058 (RC): 71-74m, 3m @ 1.74 g/t.
From the data review undertaken by Okapi, the historical drilling appears to have targeted outcropping material and historical workings, with the main geochemical target not drilled tested.
The soil sample results also coincide with a number of anomalous rock chip samples and historical workings. Most of the available rock chip samples appear to have been focussed on old workings and not on the main gold in soils trend, presenting an opportunity for Okapi. Historical drilling appears to have been focussed on rock chip results and not the adjacent soil anomaly.
Drilling results from drilling undertaken by LionOre in 2003 include:
LJPC004 (RC): 26-28m, 2m @ 11.04 g/t Au
LJPC005 (RC): 26-27m, 1m @ 1.64 g/t Au
LJPC0058 (RC): 71-74m, 3m @ 1.74 g/t Au
LJPC0094 (RC): 52-59m, 3m @ 0.88 g/t Au, including 1m @ 1.48 g/t Au from 56m
LJPD0105 (DD): 43.85-44.15m, 0.3m @ 1.14 g/t Au
In addition to the gold opportunity the region hosts nickel deposits in the same geological sequence present in the Lake Johnston Project.
Soil sampling program was completed in 2021 and an anomalous lithium zone above 25 ppm Li over 2,000m of strike length has been recorded including soil results of up to 86 ppm on tenement E63/3029. It was noted from basic mapping conducted during the soil program that several pegmatites were recorded in the zones of LCT mineralisation. The extent of these pegmatites will be confirmed in the near future with more detailed mapping and sampling, with a view towards finalising drilling positions.
Several gold anomalies have also been identified over 5 km in strike length and several hundred metres width on the tenement, along interpreted structures that also extend to gold anomalies on the adjoining tenement E63/1903. The semi-continuous gold anomalies are present above highly metamorphosed intrusive mafics and ultramafics and are accompanied by a zone of silver (Ag), bismuth (Bi) and tungsten (W) anomalism supportive of a gold mineral system. The highest assay values (up to 78 ppb Au) correlate well with zones of shearing and deformation observed in outcrop.
The results reinforce the presence of elevated gold-in-soil anomalism along interpreted structures and in proximity to intrusive felsic bodies on the tenement. The anomalies also lay north-west along strike from gold targets on the adjoining tenement E63/1903. In total, the recent work has confirmed the presence and tenor of gold-in-soil anomalism over nearly 15km of strike length on the project tenements. It was also noted that the gold anomalism is open to the north, past the end of the soil sampling program.