Aston Bay Holdings Ltd. (TSXV: BAY) has identified significant gravity anomalies in results from the high-resolution ground gravity geophysical program at the Storm Copper Project on Somerset Island, Nunavut, Canada. The programme was conducted this April and May.
“These are spectacular results from the gravity survey conducted at Storm this spring by our partners American West,” stated Thomas Ullrich, CEO of Aston Bay.
“The anomalies are large, with a strike length of several kilometres, and spatially coincident with the known shallow high-grade copper mineralization. Importantly, the anomalies are relatively shallow, with an upper boundary at about 200m depth, well within range of the diamond drill.
“The upper margin of one of the largest gravity anomalies was intersected by drill hole ST22-10 in the 2022 drill campaign. Targeting a conductivity anomaly, the hole ended in 68m of sulphide mineralization. Being both dense and electrically chargeable, the sulphide is a plausible cause for both the gravity and conductivity anomalies.
“Further, the dominantly pyrite-chalcopyrite sulphide mineralization in the intercept is the style of mineralization found on the periphery of the high-grade copper zones elsewhere at Storm. Here we have a drill hole intercepting peripheral-style sulphide mineralization on the margin of a very large gravity anomaly – this is an exciting target for the summer 2023 drill programme.”
The gravity survey is interpreted to have effectively defined a series of dense features that are spatially associated with the interpreted graben fault architecture and known copper sulphide mineralization at Storm. These geological features closely adhere to the typical sediment-hosted copper model as seen in the large copper deposits of central and southern Africa and highlight the exceptional exploration potential of the area.
The interpretation has highlighted a series of NW-SE orientated gravity anomalies along the main Storm graben axis, which are discontinuous and/or are offset in places due to a series of N-S oriented faults. The anomalies appear to have higher densities where they intersect the main graben faults, and form a series of lobes with decreasing density away from the faults.
The ‘northern fault’ gravity anomaly extends over approximately 4.8km, is located to the north of the main fault, and is broken into two main zones. The easternmost zone is located directly below the 4100N Zone, where ongoing drilling has defined thick and continuous copper mineralization in the near-surface (<100m depth) over one km of strike.
The ‘southern fault’ gravity anomaly is approximately 4km long, lies south of the graben fault, and is bounded by the 3500N, 2750N and 2200N high-grade copper zones.
A 3D inversion was completed on the gravity data to produce a series of gravity contrast iso-shells, which are designed to highlight the areas with the greatest density contrasts in 3D. These could represent potential areas of stronger copper mineralization and are high priority drill targets.
The largest of the 3D gravity targets is located along the northern fault and directly underneath the 4100N Zone. The feature commences at approximately 200m depth and is approximately 2.3km long. The gravity feature is coincident with a strong historical IP anomaly on its upper contact. This is a highly significant association and indicates a both dense and electrically chargeable body. The only known dense and chargeable geological feature at depth in the Storm area are sulphides.
Several other gravity targets are also defined by the 3D inversion along the southern fault. The data indicate that a strong gravity anomaly is located near the surface to the west of the high-grade 2750N Copper Zone. This location also features strong EM and IP anomalies associated with known copper mineralization in sparse, shallow historic drilling (5m @2% Cu and 0.8m @20% Cu in drill hole ST00-66).
Planned Programme
- Drilling at the 4100N Zone will continue in the summer field programme, with a focus on the expansion of the mineralized footprint. This programme will be followed by resource definition drilling at the 2200N and 2750N Zones – drilling here intersected high-grade copper sulfides close to surface including 41m @4.18% Cu from 38m (ST22-05), 110m @2.45% Cu from surface (ST97-08) and 56.3m @3.07% Cu from 12.2m (ST99-19).
- Processing and interpretation of the Moving Loop EM (MLEM) data collected during the spring program are almost complete.
- Diamond drilling will be scheduled to test new high-priority exploration targets identified from the gravity survey.
- Sorting and beneficiation test work for a potential direct shipping product operation is continuing with results to follow shortly.
- An environmental baseline survey is scheduled to begin this summer at Storm.
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