Highlights
- New geophysics model identifies conductor targets for deep drilling at Revere Gold Project in Western Australia
- Drilling of these new targets is aimed at intersecting VHMS (DeGrussa Style) copper-gold mineralisation to depths of approximately 300m
- Approvals in place for diamond drill program to commence in second quarter 2023
Commenting on the geophysical interpretation of the Revere Gold Project, Executive Chairman & Chief Executive Officer Mark Caruso said:
“The remodelling of the historic geophysical data using up to date technology highlights the potential of volcanic hosted massive sulphide copper-gold mineralisation within the Revere Gold Project. The predicted targets within the 3D geometry optimises the chances of success with our forthcoming deep diamond drilling program”.
Everest Metals Corporation Limited (ASX: EMC) (“EMC” or “the Company”)is pleased to announce the results of new geophysical modelling designed to optimise targets of an upcoming deep drilling program, testing for copper and gold at the Revere Gold Project (“RGP”) in Western Australia.
PROJECT INFORMATION
The project is located just off the Great Northern Highway approximately 90km to the northeast of Meekatharra in the Murchison Region of Western Australia. The tenement package size, including the tenements under option cover an area of 82km2. This is comprised of granted tenements E51/1766, E51/1770, P51/3240, P51/3241, and pending applications M51/905 E51/2119, E51/2088 (Figure 1). The project sits proximal and along strike of the DeGrussa and Monty Copper-Gold mines, just 55km to the southwest.
The Revere Gold Project is located in the Palaeoproterozoic Yerrida Basin – Doolgunna Formation. The alteration system appears to represent a classic precious metal ductile shear system – the Revere Reef System – that is associated with the Capricorn orogenic event. The historical geochemical anomaly is interpreted to represent hydrothermal mineralisation. Visual observations of the lode material from the Revere Reef indicate that coarse visible gold is contained within gossan iron oxide which forms the matrix of the quartz breccias.
Field assessment by Enterprise Metals (2009-2017), Mineral Commodities (2018-2021), and recent technical review and data interpretation by EMC demonstrated the potential of the Doolgunna formation to host DeGrussa-style Volcanic Hosted Massive Sulphide (“VHMS”) and Plutonic-style orogenic gold deposits. Historical exploration primarily focused on gold targets that could be mined by shallow open pit methods. Deeper exploration was generally limited to the immediate shallow RC drilling seeking to locate quartz vein-bearing gold.
At depth, the anomalous high copper, zinc, and arsenic values indicate the potential for a DeGrussa type copper-gold deposit below the zone of complete oxidisation. Copper and even gold lodes in the region are generally shear hosted shoots, narrow and long, comprised of high-grade lodes. The DeGrussa deposit was discovered in follow up drilling of a zone of oxide gold mineralisation similar to that found at the Revere Gold Project. The west-northwest striking breccia shear zone is interpreted to be related to deep-seated structures and to represent part of a plumbing system for metalliferous fluids that migrated upwards into suitable trap horizons – the quartz breccia or any other suitable structural traps.
GEOPHYSICAL INTERPRETATION
The Company engaged Resource Potentials, a registered geophysical dataset agent for ‘multi-client’ surveys of DMIRS for modelling and interpretation of existing geophysics data over the Revere Gold Project. This model was used to compile a geochemical, geological, and drilling database to optimise the planned deep drilling program for VHMS-type mineralisation at depth. The geophysical database including Gravity, Magnetics, Radiometric, VTEM, Electrical Resistivity, and Induced Polarisation has been processed and interpreted by specialist geophysical consultants. Reprocessing and interpretation of historical geophysical data using new modern technology has identified multiple prospective conductors and drill targets.
Revere Gold Project is situated in Doolgunna Graben between Goodin and Southern faults (Figure 2A). The northeast-southwest trending magnetic structure parallel to the southern fault is known as the Revere Reef (Figure 2B). Along the southern fault, within the Doolgunna sediments, there are areas of intense magnetism (probably magnetite/pyrrhotite) broken by areas of magnetic lows which may represent total magnetite destruction. The magnetite destruction is potentially the result of the outflow of reducing fluids, including copper.
The historical helicopter-borne Versatile Time Domain Electromagnetic (“VTEM”) survey (late time, Channel 30) data indicated that there are several discrete conductors along the northern margin of the magnetic anomaly which require follow up deep drilling. A significant conductor was defined immediately north of the Revere, DD, and Tree quartz reefs (Figure 3). Data from the VTEM survey indicates that this discrete conductor strikes northeast. The strongly conducting nature of the EM anomalies suggested that they were either massive sulphide or highly graphitic bodies. Considering the anomalies are hosted in a sedimentary package, and the proximity to the target stratigraphy is conformable to reduced facies and could be shale through to conglomerate. Furthermore, Induced Polarisation (“IP”) profiles over the Reefs and magnetic anomalies detected strong conductors on the northern margin of the magnetic body[1].
Previous drilling, primarily focused on gold targets that could be mined by shallow open pit methods. Historical RC drilling in the area has been sporadic and poorly oriented, with many holes potentially oriented in the same direction as the strike of the gold-bearing structures, where they have been oriented to best intersect the overall structural trend. However, a number of RC holes targeted VTEM and IP conductors and intersected siltstones and graphitic black shale quartz veinlets and volcanic breccia containing pyrite, arsenopyrite, and trace chalcopyrite. Anomalous copper, zinc, arsenic, and gold values at depth are more associated with the shear/fault zone and interpreted anticline hinge (e.g., 2640ppm at 12m (DRC034) and 1150ppm at 22m (DRC033)[2]). However, increasing copper and zinc grades at depth indicates the highly oxidised/leached nature of the near surface environment. Additionally, these sulphide mineralisation and geochemical anomalies remain open at depth.
During the reinterpretation of data, conductor plate modelling of the EM decay data was carried out by using Maxwell EM modelling software and was reviewed and processed. The target areas for deep drilling are the VTEM conductors, especially those located on or near interpreted structures between the major fault zones, and it is associated with the west-northwest striking breccia zones interpreted to be related to a deep-seated structure that provides a pathway for metalliferous fluids that migrated upwards into suitable trap horizons (e.g., the quartz breccia). Many modelled conductance plates remain untested by drilling and represent priority target areas (Figure 4).
Historically, multiple RC holes were drilled into the conductor trends. These related to shale and were non-magnetic. VHMS ore minerals assemblage displays weak conductivity, even though they do have magnetic properties. The new model targets a discrete conductor that coincides with a discrete magnetic anomaly and suggests possible pyrrhotite mineralisation. Chalcopyrite and sphalerite are not strong conductors, and their conductance mostly depends on concentrations of associated pyrrhotite. The modelled conductive plates identified seven new target areas, adjacent to previously drilled conductors. Five of them ranked as priority 1 and two of them as priority 2. Deep drill holes up to approximately 300m are planned to test separate plates and the Company intends to commence an initial 1,000m diamond drilling program in the June quarter 2023 to drill three deep holes at priority targets to test mineralisation
An application for the Western Australian Government’s Exploration Incentive Scheme (“EIS”) co-funded drilling was submitted to the Department of Mines, Industry Regulations, and Safety in February 2023. Subject to the success of the application, the government will reimburse the Company up to 50% of the costs for a single deep hole.
A summary of important assessment and reporting criteria used for this Exploration Results announcement is provided in JORC Table 1 in accordance with the checklist in the Australian Code for the Reporting of Exploration Results, Mineral Resources, and Ore Reserves (the JORC Code, 2012).
NEXT STEPS
- Bulk sampling, metallurgical test works, and diamond drill program to commence late Q2, 2023.
[1] ENT, Annual Mineral Exploration Reports, Combined Tenement Group No. C213/2008, (WAMEX A84456, A87533, A99937 and A109599).
[2] MRC, Annual Mineral Exploration Reports, Combined Tenement Group No. C72/2019, (WAMEX A120658 and A127726)
