- Assay results reinforce a wide corridor up to 8.5 km of base metal sulphide mineralisation at Revere Gold and Base Metals Project (“Revere”)
- Near surface gold mineralisation feeders confirmed at depth, pathfinders indicate potential for a large orogenic gold system to exist
- Downhole Electromagnetic Survey indicates the extent of multiple strong conductors as drill targets for base metals
- Follow up drilling planned for the June 2024 quarter
- Bulk sampling programme mobilisation schedule nearing completion
“These results from EMC’s first pass deep holes confirm the potential of the Revere Project to host multiple copper-gold-zinc deposits given the significant mineralisation intersected at targets spread over an area of 8.5km2. DHEM surveys indicate the conductive plates extend to the survey tool open limits. Mineralisation is open both laterally and in down-plunge directions. Leading Area Geologist Mr Bruce Hooper has confirmed results display a typical Orogenic Gold signature and provide excellent follow up targets, which compliment EMC’s prolific gold at surface, to be quantified with the bulk sampling program over the coming months. Cognisant of the results, EMC continues to consolidate its footprint around the project area, and we look forward to updating the market further in the near future”.Commenting on the drilling results at the Revere Gold and Base Metal Project, Chief Operating Officer Simon Philips said:
Everest Metals Corporation Limited (ASX: EMC) (“EMC” or “the Company”)is pleased to provide drilling results of the deep drilling program, designed to test the base metal potential at the Revere Gold Project (“RGP” or “Revere”) in Western Australia, 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.
What work has been completed at the Revere Deeps Project?
Drilling and Assays
To date, the Company has drilled 5 x Diamond Holes and 1 x RC, all of which have encountered zones of mineralisation anomalous for Zn, Ag, Cu, Au and As.
In addition, the Company has undertaken DHEM surveys on REV-01, REV-05, REV-03 and REV-04 with three of these holes encountering multiple significant conductors at depth.
|DHEM No Anomalies
What has the results of this work demonstrated?
Based on work to date the Company has delineated an extremely large footprint of mineralisation approximately 8.5km by 2.5km in size totalling 22km2, which is currently open NE-SW and at depth.
The geological similarities and intersected mineralisation in all drill holes strongly suggests the potential existence of a substantially mineralised system at Revere similar to what can be seen at the Thaduna Green Dragon and the sedimentary hosted Enigma prospect.
The drillhole assays and the base metals signatures so far detected, supports the Company’s geological theory that there is strong potential for Orogenic gold and SEDEX (and possibly VHMS) ore bodies to exist in the Doolgunna graben formation and further exploration at the Revere Project is definitely warranted.
What is the way forward ahead?
The 6 x holes drilled by the Company to date have intersected the lense and/ or the peripheral of the source (feeder) of the main ore body of mineralisation. In order to hone in on this source, further drilling followed by a DHEM and air core program is required in order to test the geochemical occurrences and VTEM anomalies as the Company systematically works to pinpoint the source of this extensive system.
Please refer to the announcement below for a detailed report of this summary.
PHASE-1 AND 2 DEEP DRILLING RESULTS
The Phase-1 drilling program with three diamond deep holes (REV-01, REV-04 and REV-05) for a total of 1038.4 meters was completed at RGP and sulphide mineralisation was intersected in all holes. Some of the thickest and highest grade intersections are outlined below:
- Hole REV01 – between 329‐338m, intersected 9m anomalous zinc (Ave.112ppm Zn) and a 4m encountered additional zone of anomalous zinc from 377‐381m (Ave. 107ppm Zn), also 2m from 207-209m (Ave.115ppm Zn).
- Hole REV04 – significant silver intercepts coincident with zinc, a 3m zone of anomalous zinc, copper, and silver from 166.5‐169.5m intersected (Ave. 27.8g/t Ag, 248ppm Zn and 190ppm Cu), including 1m at 83.5g/t Ag and 435ppm Cu from 166.5-167.5m.
- Hole REV05 –a 4m gold and zinc zone between 310.8-314.8mencountered with average 0.4g/t Au and 483ppm Zn and arsenic was anomalous over 14m from 300.8‐314.8m (Ave. 42ppm As), including 1m at 0.97g/t Au and 1710ppm Zn from 313.8-314.8m. A lower gold zone at 146.5-147.5m and 118.4-119.4m intersected respectively 0.51g/t Au and 0.37 g/t Au.
Figure 1: Phase-1 drillhole (yellow) and Phase-2 (red) collar locations. VTEM target outlines (black) 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.
During the Phase-2 drilling campaign, two diamond deep holes (REV-02 and REV-03) and one RC hole (REV-06) for a total of 1078.1 meters were completed. The intervals of the cores with sulphide mineralisation were selected for assaying and were marked up and recorded for cutting. Samples consisted of ½ core splits from core and one-metre splits from RC chip samples. A total of 119 drill samples were submitted to the ALS laboratory in Perth for multi-element analysis using four acid digest method with ICP-MS finish and fire assay for gold.
- Hole REV03 – the hole was drilled in the Revere Reef zone and about 850m northeast of the Revere costean to a depth of 402.2m to test electromagnetic conductors at depth (Figure 1 and 2). The hole intersected an upper sedimentary sequence consisting of interbedded siltstone, shale, and basalt (3-102m) before passing through graphitic carbonate iron oxide (hematite) rich (102- 319m). The drill hole was terminated in graphitic silicified dolomite with disseminated sulphides and numerous quarts-carbonate veinlets being intersected from a depth of 319m to the end of hole. Additionally, silicified dolomite with graphitic sulphide rich alteration zones and hydrothermal alteration was well developed in this hole. The dolomite exhibited a high degree of silicification and fractures and suggests the potential presence of a volcanic breccia pipe feeder source in close proximity. Two gold anomalies were intersected – 295.4-296.4m at 0.1 g/t Au and 306.4-307.4m at 0.2 g/t Au – and several zones of elevated zinc, copper, lead, silver, arsenic, and antimony were encountered:
- 6m @ 233ppm Cu, and 56ppm As from 219.2m ‐ 225.2m
- 3m @ 381ppm Cu, 103ppm Zn and 102ppm As from 274.4m ‐ 277.4m
- 3m @ 208ppm Cu and 106ppm As from 281.1m ‐ 284.1m
- 6m @ 420ppm Cu, 1.2g/t Ag, 17.7ppm Sb and 72ppm As from 292.4m ‐ 298.4m
- 3m @ 403ppm Cu, 1.1g/t Ag, 15.3ppm Sb and 66ppm As from 304.4m ‐ 307.4m
- 7m @ 0.4% Zn, 277ppm Cu and 11ppm Sb from 339.2m ‐ 345.8m (including 2m at 0.8% Zn and 378ppm Cu)
- 4m @ 0.2% Zn, 172ppm Cu, 9.1ppm Sb, 205ppm Pb and 41ppm As from 367.1m ‐ 371.1m
- 3m @ 0.5% Zn, 180ppm Cu, 141ppm Pb and 43ppm As from 378.6m ‐ 381.6m
- 2m @ 320ppm Cu, and 56ppm As from 389.6m ‐ 391.6m
- Hole REV02 – the hole was completed to a depth of 375.9m. REV-02 was approximately 1200 meters south of the Revere costean and targeted the modelled conductive plates identified from the VTEM survey in the Revere Reef (Figure 1). Hole REV-02 was inclined at 60 degrees to the southeast (azimuth 45 degrees). Logging of cores indicated siltstone (7-84m), then shale, basalt, and graphitic shale (84-150m) and silicified dolomite with graphitic sulphide rich alteration zones (245-375.9m, EOH). Moreover, the elevated levels of copper and zinc were primarily associated with hydrothermal fluids present in the graphitic alteration zones.
- 8m @ 116ppm Zn, and 55ppm Pb from 263.8m ‐ 266.8m
- 3m @ 170ppm Zn, 146ppm Pb and 140ppm Cu from 283.2m ‐ 86.2m
- 1m @ 323ppm Zn, and 146ppm Pb from 336.1m ‐ 337.1m
- Hole REV06 – a vertical Reverse Circulation (RC) borehole was drilled to a depth of 300 meters and took place at the centre of conductor plate with a dimension of 300m x 150m in the northeast of the REV-01 drillhole. The purpose of this drilling was to investigate a conductor plate that had been modelled for a discrete anomaly centred at a depth of 305m downhole. The hole intersected siltstone (27-53m) and graphitic shale (53-120m) before penetrating the graphitic carbonate breccia and shale unit (120-170m) and terminating in basalt and graphitic basalt to EOH (170-300m). Sulphide mineralisation consisting of minor pyrite and pyrrhotite, was observed within graphitic basalt at depths ranging from 285 to 300 meters. An 8m highly anomalous zone at 163ppm Zn, and 55ppm Pb was intersected from 288m -596m.
The geochemical results from the drilling were anomalous gold, copper, and zinc as well as associated trace element geochemistry Ag, Sb, As, Pb, etc. Summary assay results for sulphide intersections at diamond holes REV-03, REV-04, and REV-05 are shown in Table 1 below with full assay tables of drilled holes available in Appendix 2.
Table 1- Revere drilling, significant anomalous precious and base metal geochemistry
- All widths are down-hole, true widths are not known.
The results provide evidence of extensive mineralisation occurrences with large alteration zones which have the potential to contain ore grade base metal concentrations. Although the high-grade intersections returned from these diamond holes are narrow, the overall tenor and grade of the mineralisation encountered is encouraging and supports continued exploration along this corridor.
Figure 2: A schematic cross section shows deep drill holes at the Revere Project along with a simplified geological setting of the Doolgunna Graben (looking west)
Based on specific criteria, including the regional gravity gradient zone, local residual gravity anomalies, northwest crosscutting structures identified through magnetic data interpretation, areas where residual gravity anomalies overlap with magmatic interpreted crosscutting structures within sedimentary formations, the presence of bedrock conductors, and favourable lithological characteristics within the project area, there is a strong indication of significant potential for gold and base metal mineralisation. Furthermore, at depth, the presence of anomalous high values of copper, zinc, and arsenic suggests the potential of orogenic gold and sediment-hosted base metal deposits (SEDEX) type mineralisation beneath the oxidised zone. It’s worth noting that copper and gold occurrences in the region are typically found in shear-hosted shoots, which are narrow and elongated deposits characterised by high-grade mineralisation.
The Revere Project is located in the western margin of the basin with similar setting to structural hosted copper seen at Thaduna Green Dragon (8.2 Mt @ 1.8% Cu) and the sedimentary hosted Enigma prospect located to the northeast of Green Dragon. The geological observations made during the logging of drill holes at Revere reveal the stratigraphy of siliciclastic high-energy environment of the Mooloogool Group within the Yerrida Basin that hosted sedimentary-hosted quartz-sulphide mineralisation in graphitic black shale (Figure 3).
Figure 3: Regional Geology of the Yerrida, Bryah and Padbury groups with major deposits, adapted from Johnson et al. (2013) and modified after Hawke et al. (2016), showing geological setting of the Revere project.
Noteworthy, REV-04 was drilled north of the Southern Boundary Fault and REV-05 drilled south of the Goodin Fault, about 6.5km apart and REV-01, REV-02 and REV-03 in between, at a distance of 1.3-1.8km. (Figures 2 and 4). Drilling has intersected the Conductors which correlate strongly with significant graphite in the sediments and are especially associated with structures. Quartz-Sulphide veining is in parts associated with these shear zones especially in hole REV-03 and REV-05.
The geological similarities and intersected mineralisation in drill holes strongly suggests the potential existence of a substantially mineralised system at Revere. The drilling and analyses received to date suggest that the electromagnetic features represent mineralised volcaniclastic breccia, peperitic mafic basalt and turbiditic sediments, graphitic carbonate, silicified dolomite, and shale sequences containing disseminated and semi-massive sulphide mineralisation as well as disseminated and vein style base metal mineralisation, is closely associated with silica flooding and dominated by pyrite- pyrrhotite and chlorite- sericite- hematite alteration. Generally, sulphide mineralisation appeared from a depth of 150- 200m beneath the red-brown siltstone. Particularly, mineralisation found associated with breccias, sulphides (Pyrite), graphite and quartz veins. Strong magnetic anomalies within the sedimentary basin provide an excellent brittle host setting for gold deposition. Thick Dolomites, carbonaceous sediments, mafic volcanics, thin mafic volcanics intersected in some sequences and strong structural displacement create a favourable environment for gold and base metal mineralisation.
Figure 4: Map showing location of Revere deep holes over colour gravity with 1VD filter applied over a greyscale magnetic derivative image (TMIRTP 1VDAGC), and gold mineralisation outlines (red)
Strong lithological control on multi-element assay represents high Ca, Mg, Mn in Dolomite (e.g., REV-04), high Fe, Mg, Ti, low Mn in mafic rocks (e.g., REV-05) and low Fe, Mn, high V, S in sediments. The drilling has provided significantly improved stratigraphic control, with a focus on tracing intersections of quartz veins/veinlets, sulphide mineralisation and alterations. The drillhole analyses also explains the highly anomalous values of Cd, As, Te, W and Sb which are the base metals signatures so far detected and provide strong support for the Company’s orogenic gold and SEDEX targeting models in the Doolgunna graben and further exploration at the Revere Project. However, due to some similarities between VHMS and SEDEX, coupled with the limited number of borehole and assay data for an early-stage project, it is too early to determine which mineralisation type and metallogenic model is more dominant for base metal mineralisation. It is worth noting, the occurrence of volcanic breccia rocks with hydrothermally mobilised sulphides and trace element geochemistry of assay data is conformable to the classic VHMS metal zonation model which was caused by the changing physical and chemical environments of the circulating hydrothermal fluid, while the increased presence of black shale and/or carbonate lends support to the SEDEX model, along with a higher zinc content in comparison to copper. This is further underscored by the presence of banded pyrite/pyrrhotite, sphalerite, and chalcopyrite, along with the observation of carbonate veining in certain intervals and increase of phosphorus with the zinc and silver. Nonetheless, superimposition of late phase mineralisation linked to hydrothermal (mesothermal) alterations, especially within the shear zone, hinders the clear evaluation and assessment of the mineralisation system at the Revere Project. For example, at drill hole REV-04, significant anomalous pathfinder elements that occur in association with copper and zinc, exhibit an average of Ba 319ppm, Sb 8ppm, Cd 2ppm, P 454ppm, As 45ppm, W 4.9ppm and Te 0.7ppm and contained elevated maximum values in individual drilling assay Ba 700ppm, Sb 30 ppm, Cd 21ppm, P 2240ppm, As 196ppm, W 26ppm, Te 32ppm.
The Yerrida Basin sedimentary package also contains a number of the key elements necessary for SEDEX style base metal mineralisation, including evaporites, siliciclastic, hydrocarbons and basin bounding faults. Extensive exploration activities were completed in the late 1980’s and 1990’s focussed on discovery of base metal deposits using this model. Exploration drilling by Enterprise Metals Limited testing the SEDEX style Borg and Bono targets about 25km to the northeast of Revere project has identified anomalous levels of base metals and pathfinder elements associated with sulphides hosted in carbonaceous shales. The rocks exhibit enrichment in Mg, P, Mn, Fe, Ni, Cu, Zn, As, Sb, Ti and Pb. Notably, the concentrations of certain elements stand out, with levels significantly exceeding their corresponding background concentrations. This suggests that pyrite is likely the main host mineral for these elements. Specifically, Co (average 16 ppm, maximum 128 ppm), Ni (average 49 ppm, maximum 223 ppm), Cu (average 75 ppm, maximum 768 ppm), As (average 21 ppm, maximum 196 ppm), Ag (average 0.5 ppm, maximum 77 ppm), Sb (average 3 ppm, maximum 31 ppm), Ti (average 0.4 ppm, maximum 1.3 ppm), and Bi (average 0.3 ppm, maximum 1.8 ppm) all show significant enrichment.
From the geochemical perspective, the presence of Ba, Pb and the high anomaly of silver with an average of 0.6g/t and 83.5 g/t Ag associated with strongly anomalous zinc values up to 0.8% are suggestive of a distal SEDEX mineralisation halo. Whereas the more easily transported volatile elements like Sb may produce halos which may extend over several hundreds of metres and are therefore amongst the most investigated fluid-mobile elements in sedimentary hosted base metal systems. It seems the mineralised part of the drill holes intersected halo mineralisation/stringer zone containing pyrite, and fine grain sulphides sphalerite/galena. Sphalerite is associated with early-stage exhalative mineralisation, intermediate sulfidation hydrothermal suite minerals and sulphide minerals enriched in the hydrothermal trace element suite (Au, Ag, As, Bi, Co, Sb, etc.). This emphasises the potential of sedimentary hosted base metal systems in carbonaceous shale units in the margin of basin, close to the Goodin Fault and the Southern Fault as well as orogenic gold targets at Revere (Figure 5).
The results provide evidence of extensive mineralisation occurrences with large alteration zones which have the potential to contain ore grade base metal concentrations. Although the high-grade intersections returned from these holes are narrow, the overall tenor and grade of the mineralisation encountered is encouraging and supports continued exploration along this corridor.
Figure 5: Breccia zones with sulphides, graphite, typical orogenic gold setting from REV04
DOWNHOLE ELECTOMAGNETIC SURVEY
Following the completion of Phase-2 drilling, the Company carried out an additional Downhole Electromagnetic (“DHEM”) survey on two deep drilled holes to search around the holes at depth for potential conductors that might indicate the presence of massive sulphide mineralisation.
The location of the DHEM transmitter (“Tx”) wire loop is important to ensure the primary EM field generated by the Tx electrically couples with conductive targets in the ground. If an electrical bedrock conductor is “null-coupled” to the primary EM field generated by the Tx loop, then the conductive source body would be invisible to this DHEM survey configuration. Tx loops for the recent DHEM surveys were single-turn wire loops measuring approximately 500m x 500m (REV-04) and 600m x 400m (REV-03) in dimensions and were positioned to provide EM coupling with interpreted target orientations. A Tx frequency of 1Hz was used to identify slowly decaying anomalies related to strong conductors, as well as quickly decaying sources related to weak conductors. The DHEM survey data has been processed and interpreted by specialist geophysical consultants.
The DHEM survey in REV-03 identified multiple overlapping conductor anomalies and suggests multiple conductor sources with variable locations and orientations in a complex geological setting. The anomaly shapes observed between the different components help to determine the location and orientation of the conductor source relative to the drillhole trace, whereas the DHEM decay channels in which an anomaly is observed indicates the electrical conductance of the source.
Figure 6: 3D view looking south and down on the REV-03 drillhole trace (black line), DHEM Tx loop (black outline) and DHEM modelled conductor plates coloured by electrical conductance.
The 10 conductor plates modelled from the REV-03 DHEM data range in size, orientation, and electrical conductance, formed a complex conductive area (Figure 6). Additional DHEM surveying in new drillholes in this area are highly recommended to help constrain this conductor model and test different parts of the conductors to determine which may be related to base metal mineralisation.
The REV-04 DHEM survey identified two long-wavelength anomalies suggesting large conductor sources, as illustrated by the DHEM mid-late decay channel profiles to the bottom left using linear scale. The first anomaly is a clear response centre data approximately 115m downhole. The negative peak in the A component data suggest an off-hole conductor source, and the crossover inflection anomalies in the U and V component data suggest the source to be located below, or downdip (NW), from the drillhole trace. The second anomaly identified in REV-04 is alate-time decay anomaly growing beyond the end of the survey depth suggesting a large and conductive source located far below and to the SE of the drillhole trace.
The two DHEM conductor plates located downdip from drillhole REV-04 coincide with VTEM conductor plates modelled in this area, (Figure 7) and drill testing the second conductor plates is recommended to evaluate base metals mineralisation. The large and blue conductor plate located below and SE of drillhole REV-04 is thought to present a stratigraphic conductor and is not considered to be a drill target.
Figure 7: 3D view looking NE and down on the REV-04 drillhole trace (black line), DHEM Tx loop (black outline) and DHEM modelled conductor plates coloured by electrical conductance.
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).
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 8). The project sits proximal and along strike of the DeGrussa and Monty Copper-Gold mines, just 55km to the southwest.
Figure 8: Revere Gold Project location
RGP is situated in the Palaeoproterozoic Yerrida Basin siliciclastic, within Doolgunna Graben – Doolgunna Formation. The Yerrida Basin has a faulted contact with the Bryah Basin in the northwest (Goodin Fault) and unconformably overlies, or is in tectonic contact with, Archaean granite-greenstone rocks of the Yilgarn Craton and the Marymia and Goodin Inliers to the south and east. A second major fault parallel to the Goodin Fault is recognised in the project area; termed the Southern Boundary Fault, which offsets the Yerrida Group units. The system is associated with the Capricorn orogenic event. The alteration system appears to represent a typical classic precious metal ductile shear system, known as the Revere Reef System. 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 assessment and data interpretation conducted by EMC demonstrated the potential of the Doolgunna formation to host volcanic hosted massive sulphide (“VHMS”), sediment hosted base metals (“SEDEX”) and Plutonic-style orogenic gold deposits. The Company undertook a process of remodelling and reevaluating historical geophysical data using modern technology. The new developed model is designed to target a discrete conductor that coincides with a discrete magnetic anomaly, potentially indicating the presence of pyrrhotite mineralisation. It’s important to note that chalcopyrite and sphalerite, while not inherently strong conductors, may exhibit conductivity depending on the concentration of associated pyrrhotite. The modelled conductive plates have identified fresh target areas adjacent to previously explored conductors. Data obtained from the VTEM survey indicates that this discrete conductor strikes northeast. The strongly conducting nature of the electromagnetic anomalies suggest they could be either massive sulphide or highly graphitic bodies. Considering that these anomalies are found within a sedimentary package and are in close proximity to the target stratigraphy, it’s conceivable that they are associated with reduced facies, possibly shale formations. A significant conductor was defined immediately north of the Revere Reef, south of DD Reef, and southwest of Tree Quartz Reef (Figure 1). The Phase-1 and 2 drilling programs were designed to test the separate plate conductors considered to be priority targets, a deep hole in each reef system. In July 2023, EMC completed the Phase-1 drilling program designed to test the separate plate conductors which are priority targets, drilling deep holes into each reef system. Initially, 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. The Phase-2 drilling commenced in August 2023 to continue to test the VTEM conductors and a DHEM survey over Phase-1 drill holes was then completed.
- Further drilling over the DHEM and VTEM target areas across the tenement is planned for 2024;
- Continued planning for 36,000 tonne bulk sampling program proposed to commence Q1, 2024; and
- Regional Air core program to further test Geochemical occurrences.
 ASX: SFR announcement; Resource Estimation report for Thaduna/Green Dragon deposit, dated 19 October 2017
 ASX: SRI announcement; New ‘Record’ Intersection at Enigma 34m @ 2.8% Cu, including 11m @ 7.6% Cu, dated 24 August 2013
 ASX: ENT announcement; DOOLGUNNA PROJECT: BORG – BONO BASE METAL TARGETS CONFIRMED, dated 24 December 2015
 ASX: EMC announcement; Drilling Recommenced at Revere Gold-Copper Project to Test Prospectivity for Massive Sulphide Mineralisation, dated 10 August 2023
 ASX: EMC announcement; Geophysical Modelling Identifies Deep Drilling Targets at Revere Gold Project, dated 7 March 2023
 ASX: EMC announcement; Drilling Identifies DeGrussa Style Mineralisation Under Revere Gold Project, dated 12 July 2023
 ASX: EMC announcement; Drilling Recommenced at Revere Gold-Copper Project to Test Prospectivity for Massive Sulphide Mineralisation, dated 10 August 2023