Westar Resources Ltd (ASX:WSR) is encouraged by the results of a geological reconnaissance fieldwork program at the 100%-owned Opaline Well Project in the Pilbara of Western Australia that defined a base metal mineralisation trend.
This helicopter-assisted program included traverse mapping and rock chip sampling at previously identified airborne electromagnetic (AEM) conductors along with multiple base-metal, cobalt and gold prospective targets identified from previous fieldwork and compilation of historical data.
AEM gold and base metal target areas were traversed with rock chip samples collected assayed by ALS. One sample, OWK0028, returned 0.89% lead, 3.1ppm silver and 0.1% zinc while another, OWK0032, returned 0.23% zinc.
“Rapid assessment”
Westar managing director Karl Jupp said: “Westar is pleased to have geologists back on the ground at Opaline Well and the heli-supported reconnaissance program has enabled rapid assessment of all targets.
"Whilst surficial explanations of the AEM conductors were not readily observed during the reconnaissance, the identification of several leached gossans and rock chips with base metal signatures is highly encouraging for the potential of the project.”
Program objectives
Westar geologists recently completed the helicopter-assisted reconnaissance program at Opaline Well, which is about 190 kilometres southeast of Port Hedland and 35 kilometres west of Nullagine in the highly prospective Pilbara Mineral Field.
The objectives included ground truthing areas with identified AEM conductors, traversing interpreted ultramafic units as a potential source of regional cobalt anomalism and assessing the potential for gold mineralisation within basin-like geomorphological settings.
A large suite of lithologies was traversed and sampled, including potential leached gossans. Target (NYSE:TGT) areas included Basin targets (North, Central and South), anomalies 101/201/202/203, anomalies 200/102/103/104 and Dalton prospect.
Basin targets
Basin Central and South were observed to be considerably more structurally deformed and complex than Basin North, including a large recumbent fold and extensive quartz veining noted to intrude and cross-cut the chert ridge in Basin Central.
Fieldwork and rock-chip sampling by Westar in 2021 identified base-metal enriched quartz veins within a low ironstone ridge to the east of the Basin North target.
Follow-up in the recent campaign identified sedimentary units in contact with a gossanous mafic horizon and rock-chip sample OWK0028 was noted as an intensely altered and foliated mafic, with the base metal mineralised sampled adjacent to a 1-metre-wide quartz vein.
Evaluating rock chip samples together with historical rock chip assay data, Westar has delineated a ~700 x 1200-metre Basin North mineralised trend, indicating the potential for a large mineralised system.
Anomaly 101 target
Anomaly 101 is interpreted to represent a highly conductive body and was the priority area of interest for the survey.
The anomaly is around 800 metres long, sub-vertical and considered prospective for VHMS style mineralisation due to late-time AEM response, stratigraphically conformably orientation and lack of mapped or interpreted graphitic shales in the area.
Anomalies 201/202/203 are broad, large amplitude, early time, Z component AEM anomalies speculated to be a resultant weathering product from the deeper underlying and more conductive Anomaly 101.
Anomaly 101 Chert ridgeline.
Surficial explanations for the conductors were not readily observed during the reconnaissance, however, the measured orientations of outcropping shale, volcaniclastics, chert and mafic units proximal to the AEM 101 conductor anomaly suggest the possibility of confined bedrock conductors such as massive sulphide accumulations, below the observed surficial zone of oxidation.
Previous explorers were unable to locate any BIF horizons at Anomaly 200 and Westar considers the anomaly to represent potential for sulphide-hosted mineralisation at a sediment-basalt contact.
Surficial observations at the anomalies did not directly identify a source of the EM anomalies, suggesting the conductor source is below the oxidised outcropping units.
Dalton prospect
The Dalton prospect contains a package of ultramafic and mafic intrusive units that could potentially host layered magmatic intrusive nickel-copper-cobalt mineralisation or ultramafic-mafic hosted copper (cobalt, nickel, gold) VMS mineralisation, causative to “potentially the largest coherent cobalt-in stream anomaly in Western Australia”, identified by Anglo American (LON:AAL) stream sediment surveys in the late 1970s.
EW traverses observed large-scale folding within a package of sediments composed of micaceous metasandstone, zinc enriched (0.2%) thinly inter-laminated ferruginised chert/carbonate, shale beds and a large chert horizon.
The sedimentary package was underlain by an ultramafic unit, exposed in eroded synclinal hinges and on the eastern edge of the target area.
This ultramafic contact could possibly represent the same contact containing gold mineralisation reported in the 'Northern Zone' of Greatland Gold's Panorama Project.
Discrete areas of anomalous geology were noted, including brecciated and geothitic quartz veining and a highly weathered ultramafic with minor boxwork textures.
Brecciated Geothitic Quartz vein.
What comes next?
The field reconnaissance has greatly improved understanding of the stratigraphic and structural controls affecting mineralisation potential within Opaline Well project area.
With all rock-chip sample assays returned from ALS, Westar will integrate the information into existing datasets to establish priority prospects for further evaluation and evaluate the potential for RC and/or diamond core drilling.