Located in the richly endowed Laverton region of Western Australia, the Laverton Downs Project (LDP) has demonstrated potential to host both gold and nickel sulphide mineralisation. The LDP commences just 20km north of Laverton in the north-eastern Goldfields where it occupies some high potential mineralised real estate. World-class neighbouring mines include; Granny Smith (Au), Sunrise Dam (Au), Mt Morgans (Au), Mt Windarra (Ni), Wallaby (Au) and Rosemount/Garden Well (Au).
In 2019, CSA Global completed a project evaluation covering geochemistry, litho-structural, and mineral systems analysis and target generation – a similar program to the one completed over the Lake Wells (Yamarna) Gold Project that contributed to the joint venture with SBM. CSA concluded that the Project is prospective for both gold and nickel sulphide deposits, and that exploration is considered at an early stage.
Initial interest in the LDP came after the publication of regional scale prospectivity studies, primarily the pmd* CRC Y4 project. As a predictive tool for gold mineralisation, the Y4 project indicated that the LDP is highly ranked (Figure 1), containing many of the ingredients that other world-class gold deposits exhibit. APC has continued the mineral systems analysis through industry consultants CSA Global and distilled all available data into discrete targets, along with additional conceptual goals that have received little or no compelling exploration.
Figure 1: LDP area output from the pmd* CRC Y4 project
The LDP comprises six granted tenements: E38/2724, E38/3014, E38/3132, E38/3402, E38/3403 and E38/3404.
CSA Global has completed a desktop review the LDP that concluded:
Based on the work compiled by CSA, APC is highly encouraged to continue to explore the LDP.
The gold prospects identified are strongly anomalous with indicator elements such as antimony (Sb), arsenic (As), tungsten (W) and tellurium (Te) and support several +100ppb gold targets.
Regional geology, including known nickel deposits, highlight the potential for nickel sulphide mineralisation within the LDP (Figure 2).
Project evaluation by CSA Global utilised all available data including regional datasets, detailed magnetic data, and high precision geochemical assay results derived from bottom of hole drill samples. Targeting criteria for Kambalda-style nickel deposits is based on identifying nickel bearing ultramafic rocks in contact with sulphur rich sediments. The geochemical results confirm that the high MgO (>25%) ultramafic komatiite rock type is present within the LDP, and also confirms the presence of magmatic nickel sulphides through the relationship of Fe vs S.
Figure 2: Regional location of the Laverton Downs Project showing known nickel sulphide deposits. Regional RTP magnetic image as background.
Opportunistically in November 2020 a small portion of the project area was flown with an airborne Versatile Time Domain Electromagnetic (VTEMTM) (Figure 3). Covering 100 linear kilometres at 100m line spacing, with 50m infill lines over one target, the program was designed to detect massive nickel sulphide mineralisation within highly prospective rocks identified in the CSA Global project evaluation. VTEMTM is an airborne electromagnetic geophysical technique that is designed as a first pass massive sulphide detecting method (Figures 3 & 4).
The VTEMTM program was extremely successful with several very strong EM anomalies identified that show all the hallmarks of massive sulphide mineralisation consistent with the Kambalda-style komatiite-hosted massive nickel sulphide deposit model. Kambalda-style deposits are characterised by massive pyrrhotite-pentlandite sulphide mineralisation that is highly conductive and magnetic, meaning they are amenable to detection with electro-magnetic geophysics.
Figure 3: Helicopter-borne VTEMTM survey in action over the Laverton Downs Project
Priority targets generated from the VTEMTM survey are high amplitude, late-time, discrete anomalies. Conductor plate modelling suggests the conductor sources to be shallow, starting from approximately 100-150m below surface. Despite being considered shallow, these targets are deeper than the deepest historical drill hole that targeted nickel and are consistent with the most recent mineralisation models for the style of deposit targeted.
A diamond drilling program targeting massive sulphide mineralisation was undertaken in June 2021, focusing on the priority targets identified by the VTEMTM survey. The program comprised two holes, drilled to depths of 213.3m and 300.5m. Results confirm the geology logging where the VTEMTM geophysical response is best explained by a stringer sulphide mineralised graphitic shale.
In keeping with the gold mineralisation model for the project, several intervals returned elevated gold and arsenic results, with a peak interval of 8m @ 147ppb Au and 782ppm As from 274m in hole 21LDDD002. Along with the ongoing collection and assay of legacy drill spoils, these results build on strong gold focused targets for future drilling campaigns.
Australian Potash Limited:
Suite 31, 22 Railway Road
Subiaco Western Australia 6008
PO Box 180
Subiaco Western Australia 6904
Tel: +61 8 9322 1003
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