Drilling Recommenced at Revere Gold-Copper Project to Test Prospectivity for Massive Sulphide Mineralisation Identified by Down Hole Electromagnetic Survey (DHEM)
Highlights
- DHEM results show conductive sources, confirming prospectivity for massive sulphide mineralisation
- Phase-2, 1,000m drilling campaign has commenced, comprising 3 x ~300m drill holes
- Phase-2 drilling programme targets the DHEM modelled conductor plates as well as untested VTEM anomalies
Commenting on the DHEM results and recommencement of the drilling program at the Revere Gold-Copper Project, Chief Operating Officer Simon Philips said:
“The DHEM survey results are a part of a further systematic geological approach in identifying where we need to be to follow up the significant visual mineralisation encountered in our phase 1 diamond drill program. This systematic approach and the results continue to confirm the outstanding potential at the Revere Gold-Copper Project.”
Everest Metals Corporation Limited (ASX: EMC) (“EMC” or “the Company”)is pleased to provide an update on exploration activities at the Revere Gold Project (“RGP”) in Western Australia being the DHEM results and commencement of the phase-2 deep drilling campaign, designed to follow up and test the copper and gold potential at the Revere Project.
BACKGROUND
The project is located just off the Great Northern Highway approximately 90km to the northeast of Meekatharra in the Murchison Region of Western Australia and 900km north of Perth. 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 and E51/2145 (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-Copper 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.
The 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. At depth, the anomalous high copper, zinc and arsenic values indicates the existence for a potential DeGrussa style 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 Company carried out remodelling and re-interpretation of the historic geophysical data using up to date technology – the results highlighted the potential of VHMS copper-gold mineralisation within the RGP[1]. 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 new target areas adjacent to previously drilled conductors. Data from the VTEM survey indicates that this discrete conductor strikes northeast. The strongly conducting nature of the EM anomalies suggest they are either massive sulphide or highly graphitic bodies. A significant conductor was defined immediately north of the Revere Reef, south of DD Reef, and southwest of Tree Quartz Reef (Figure 3).
In July 2023, EMC completed a phase-1 drilling program designed to test the separate plate conductors which are considered to be priority targets, drilling deep holes into each reef system[2]. Three diamond deep holes (REV-01, REV-04 and REV-05) were drilled for a total of 1038.4 meters with sulphide mineralisation intersected in all holes. Mafic breccia, volcaniclastics and shales with chalcopyrite, sphalerite and pyrrhotite/pyrite were intersected at various intervals. Geological logging (lithology, mineralogy, alteration, and structure) of the three drill holes at Revere represent the same stratigraphy as the Mooloogool Group in the Yerrida Basin that hosted the world class Monty, Taduna and Green Dragon deposits all of which also have a strong synergetic relationship with the DeGrussa copper-gold deposit. The areas being investigated have proved to be highly prospective for sediment or volcanic hosted copper sulphide deposits. Assay results from phase-1 are expected to be received by mid-September 2023.
DOWNHOLE ELECTOMAGNETIC SURVEY
The Company engaged Wireline Services Group to undertake a Downhole Electromagnetic (“DHEM”) survey on deep drilled holes to search around the holes at depth for any other conductors potentially indicative of massive sulphide mineralisation. A rectangular loop of dimensions 500m x 500m was deployed around drillholes REV01 and REV05 and a transmitter frequency of 1Hz was employed. The DHEM survey data acquired in both drillholes REV01 and REV05 were of good quality. The DHEM survey data has been processed and interpreted by specialist geophysical consultants Resource Potentials.
The REV01 DHEM survey identified multiple anomalies of interest at the Revere Reef, including a mid-time off-hole anomaly centre data approximately 305m downhole. This anomaly was recorded in all 3 receiver (Rx) components and has a shortwave length indicating a conductor source near the drillhole. Also, data identified multiple long-wavelength anomalies suggesting large conductor sources. These long wavelength features were identified in early decay channels in the shallow parts of the drillhole, suggesting weakly conductive regolith, and were also identified in late decay channels, growing with increasing depth, indicating large and distant conductor sources beyond the end of the drillhole. The REV01 area is electrically complex, with multiple conductor sources, including stratigraphic conductors having variable orientations and flat lying surficial conductors in the regolith, as imaged by the VTEM survey. Conductor plate modelling from REV01 showed 4 separate conductor plates, as shown in Figure 1. Conductor Plate 1 (red) was modelled for the discrete anomaly centred at 305m downhole, has approximate dimensions of 300m x 150m, an electrical conductance of 100S, and is located approximately 20m NE from the drill hole trace. This model conductor plate is considered to be a priority target and is recommended to be drilled.
Figure 1: Left: 3D view looking NE at the REV01 drillhole trace, DHEM Tx loop and modelled conductor plates Right: Revere project tenement outlines (blue), REV01 collar location (yellow dot), Tx loop outline (black) and modelled conductor plates, all over a ternary VTEM anomaly image of EM decay channels 20 (red), 14 (green) and 8 (blue) with a 1VD filter applied, and a filtered greyscale magnetic background image.
No anomalies of interest were identified in the REV05 DHEM survey. The elevated response observed in the decay data indicate a large conductive background but cannot be a conductor plate modelled due to the lack of anomalies coincident in the different Rx components. The bumps and spikes in the late-time decay channels are considered to be system noise amplified by the logarithmic scale.
PHASE-1 DEEP DRILLING, UPDATE
A total of 1038.4 meters were completed at the Revere Gold-Copper Project with sulphide mineralisation intersected in all holes[3]. The intervals of the core that were selected for assaying were marked up and recorded for cutting and sampling. Samples consisted of 1/2 core splits from core and 147 drill samples were submitted to the ALS laboratory in Perth in late July 2023 for multi-element analysis using four acid digest method with ICP-MS finish and fire assay for gold. Assay results are expected to be received by mid-September 2023. The Company will update the market when laboratory analytical results become available.
Figure 2: An example of significant sulphide mineralisation in Revere drill cores observed during core cutting in REV-04, A: 167m, B: REV-04, 162m (refer to announcement dated 12 July 2023).
In relation to the disclosure of visual mineralisation of base metal bearing sulphides in the core which have been included in this release including photos and commentary for geological context, the Company cautions that visual estimates of mineral abundance should never be considered a proxy or substitute for laboratory analysis. Laboratory assay results are required to determine the widths and grade of the visible mineralisation (if reported) in preliminary geological logging.
PHASE-2 DEEP DRILLING PROGRAMM
Three boreholes are planned for the phase-2 drilling campaign, including two diamond deep holes (REV-02 and REV-03) for approximately 350m each, targeting the modelled conductive plates identified from the VTEM survey in the Revere Reef (Figure 3). The strongly conducting nature of the EM anomalies suggested that they are either massive sulphide or highly graphitic bodies. The targets are discrete conductors 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.
Figure 3: Preliminary VTEM target outlines (black), phase-1 drillhole collar locations (yellow) and phase-2 drill hole locations (red) including REV-02, 03 and 06 over Revere project tenement border (blue), a ternary VTEM anomaly image of EM decay channels 20 (red), 14 (green) and 8 (blue) with a 1VD filter applied, all overlying a greyscale magnetic image (TMIRTP HP500mAGC).
The third hole (REV-06) has been designed based on interpretation of the DHEM survey on drillhole REV-01 and targets a conductor plate modelled for the discrete anomaly centred at 305m downhole, with a dimension of 300m x 150m in the northeast of the REV-01 drillhole. A vertical drill has been considered for this target.
Phase-2 drilling is expected to commence on 9th August 2023 and the program is expected to take approximately 15 days. The coordinates of the planned drill hole collars, dip and dip direction are detailed in table 1.
Table 1- Details of planned deep drill holes
| HoleID | Prospect | Easting MGA94 | Northing MGA94 | Height (m) | Planned depth (m) | Dip (degrees) | Azimuth (degrees) |
| Rev-02 | Revere Reef | 701293 | 7125574 | 517 | 350 | -60 | 45 |
| Rev-03 | Revere Reef | 702108 | 7127137 | 530 | 350 | -60 | 90 |
| Rev-06 | Revere Reef | 700794 | 7127044 | 543 | 300 | 90 | 0 |
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
- Assays results of phase-1 drilling due mid-September 2023
- Initial results of phase-2 drilling programme due September 2023
- Complementary DHEM survey planned
- Continued planning of the Bulk Sampling Program at surface
[1] ASX: EMC announcement; Geophysical Modelling Identifies Deep Drilling Targets at Revere Gold Project, dated 7 March 2023
[2] ASX: EMC announcement; Drilling starts at Revere Gold Project, dated 6 June 2023
[3] ASX: EMC announcement; Drilling Identifies DeGrussa Style Mineralisation Under Revere Gold Project, dated 12 July 2023
