West Australian gold explorer Lodestar Minerals Limited (ASX: LSR) has identified new early stage gold targets for the Yowereena farm‐in tenements located immediately north of the company’s 100%‐owned Ned’s Creek project (see Figure 1).
- Data review identifies two large, untested gold geochemical targets in previous cover‐bedrock interface sampling.
- Preliminary field sampling by Lodestar has identified two additional areas of interest for further investigation:
- A potential gold trend along strike from Boundary Fence prospect.
- Strongly oxidised gossanous breccia veins on northern margin of Contessa granite anomalousin Bi, Mo and Au.
- Further fieldwork planned for both new areas
The update incorporates the results from a program of field exploration completed by Lodestar in April 2017 and an ongoing compilation and review of historical data.
Lodestar announced a farm‐in agreement with emerging gold miner Vango Mining Limited over Vango’s Yowereena tenements on 14th March 20171. Lodestar is earning up to an 80% interest in the tenements by meeting minimum expenditure commitments of A$357,000 for the project for the 12 months following the execution date of the agreement.
The Yowereena tenements comprise four granted mining leases covering the northern margin of the Contessa granite and poorly exposed Archaean basement along the southern tectonic margin of the Marymia Inlier. The Archaean sequence at Yowereena has demonstrated gold potential with high‐grade gold mineralisation reported from drilling at the Boundary Fence prospect and a number of anomalous gold intercepts in historic first‐passregional drilling. Furthermore, the geological model Lodestar has developed during four years of gold exploration at the adjacent Ned’s Creek projectsupports the potential for both syenite‐hosted and structurally controlled gold mineralisation at Yowereena.
A recent field visit and ongoing review of historic exploration data has revealed large scale gold and multi‐ element anomalism across the Yowereena – Contessa area, strongly supporting Lodestar’s belief that the area within this major tectonic zone has potential for significant discoveries.
Geological Database Review
As part of Lodestar’s comprehensive review of the available data generated from earlier exploration at Yowereena, two large gold targets beneath areas of alluvial cover have been identified from Homestake Gold’s 2001 geochemical drilling program.
Homestake carried out systematic shallow drilling in the eastern part of the project on a 160m grid spacing (maximum depth 18m) to sample the contact between transported cover and underlying weathered rock. This technique is a cost efficient way to refine areas for deeper drilling targeting bedrock gold mineralisation.
A total of 330 holes were drilled and a single 3 or 4 metre composite sample was collected from each hole at the contact (cover‐bedrock interface sampling or CBI). Each sample was analysed for gold and multi‐elements.
The CBI sampling revealed two large, contiguous anomalies (>10ppb gold) within the northeast trending structural corridor (see Figure 2). Neither target was subsequently followed up with any further drilling.
Anomaly A, located to the north, reported maximum gold to 76ppb Au partly coincident with gold anomalies along a traverse of 100m spaced aircore drilling. Three adjacent holes near the western end of the anomaly reported:
- YHAC030 – 1m at 0.316g/t Au from 58m;
- YHAC031 – 1m at 0.364g/t Au from 78m; and
- YHAC032 – 1m at 0.283g/t Au from 75m.
Anomaly A has a gold – bismuth association suggesting a fluid source derived from felsic intrusions. The next closest line of drilling is 800m south west of the anomaly.
Anomaly B occurs closer to the northern contact of the Contessa granite and reported a maximum 41ppb Au. Anomaly B has an arsenic – gold association with strongly anomalous arsenic of up to 311ppm in individual holes. There has been no bedrock drilling in the area of Anomaly B which islocated 300m north of the Contessa granite and is aligned with a northeast trending shear zone interpreted from aeromagnetic data.
Reconnaissance Sampling Program Reconnaissance surface sampling was conducted by Lodestar within the 35 square kilometre area of Mining Leases M52/779 to M52/782. The field visit was intended primarily to visit sites of previous activity, check historic drill hole locations and access for future exploration programs. In general, the samples reported here were intentionally collected from residual outcrop that had not been targeted or tested by historic sampling.
The most significant result from this program was a rock sample reporting 1.25g/t gold, 517ppm bismuth, 365ppm molybdenum and 15ppm tellurium from a siliceous ironstone breccia located 1 kilometre south west and along strike from Boundary Fence (sample results listed in Table 1). Some relevant observations are as follows:
- This sample is located on the same north‐easterly structural trend as Boundary Fence and there has been no drilling over this area or the intervening distance towards Boundary Fence.
- The metal association (Au‐Bi‐Mo‐Te) is the same as that observed at Lodestar’s Brumby prospect (syenite‐hosted) and is consistent with metal associationsreported from syenite and granite intrusion‐ related gold deposits within Australia and elsewhere.
- The sample is located on a (concealed) granite contact (interpreted from VTEM data and mapping by Marymia Exploration – see Figure 2). The regional geology placesthe granite within the Marymia Inlier; however the results suggest it may belong to the same suite as the Contessa‐Brumby composite intrusion, which is believed to be the expression of a partial melting and mineralising event within the Jenkin tectonic corridor.
Initial drilling at Boundary Fence, planned for later this year, will aim to confirm the high grade gold intercepts reported in Marymia Exploration’s 1993 historic drilling. Detailed structural mapping, to be carried out prior to drilling, willseek to identify potentialstructural controlsto assess whether historic drilling was not optimally oriented to intersect oblique or plunging mineralisation.
A second area, located at a fault offset on northern contact of the Contessa granite, hosts several slightly outcropping,strongly oxidised, gossanous quartz veins with sulphide boxwork textures (see Figure 2). The veins reported low‐level gold with weakly elevated bismuth, molybdenum and tellurium. While the sulphidic, haematite and high‐grade gold bearing veins at Brumby retain fresh pyrite, the gossanous veins are totally oxidised and may be leached of metals, including gold. The granite adjacent to the quartz veins is locally intensely albite altered which is a characteristic of intrusion‐related gold systems.
The newly identified areas will be the focus of follow‐up fieldwork, including a sampling campaign to determine the extent and significance of these preliminary results. Lodestar will continue to seek to collate any other available sources of historic data for Yowereena to assist with future targeting.
These early results at Yowereena are highly encouraging and continue to demonstrate widespread gold anomalism and the potential for this under‐explored terrain to host a significant discovery. It also further supports Lodestar’s regional geological model. The newly identified gold targets strengthen Lodestar’s inventory of targets which includes the Brumby, Contessa, Marymia and West Pinyrinny prospects.