The Storm Copper Project is located on Somerset Island, Nunavut, approximately 20 kilometres from tidewater at Aston Bay. Storm Copper is a strata-bound and structurally-hosted copper zone of mineralization, hosted in dolomitic sediments of the Allen Bay Formation. Hypogene copper mineralization is present at surface and identified to a depth of at least 100 metres in the form of chalcocite, bornite, covellite and chalcopyrite. Malachite and azurite are common oxide coatings. The geologic setting, mineralogy and zonation suggest affinities to sediment-hosted copper deposits.
Aston Bay Enters into Option Agreement with American West Metals Limited
On March 9, 2021, Aston Bay entered into an option agreement with American West Metals Limited (AWML), a private Australian company, and Tornado Metals Ltd., (a wholly-owned subsidiary of AWML) to earn an 80% interest in Aston Bay’s 100% owned property located on western Somerset Island, Nunavut which hosts the Storm Copper Project and the Seal Zinc Deposit.
HIghlights of the Option Agreement
Storm Copper has been explored intermittently since the 1960s; however, most of the historic work on the property was undertaken by Cominco Ltd. (now Teck Resources Ltd).
Sixty-seven holes (9,032.5 metres) were drilled at Storm between 1996 and 2000. These efforts defined four separate zones of copper mineralization — 2200N, 2750N, 3500N, and 4100N Zones — all of which remain open both laterally and vertically.
Highlights from the historic drilling at Storm Copper include:
In addition to the historical drill results, a 3,970 line-kilometre Versatile Time Domain Electromagnetic (VTEM) airborne survey was completed over the property in 2011. The spatial correlation of conductance anomalies with mineralized intercepts in the historic drilling suggests that the near-surface copper mineralized zones of the Storm copper property can be accurately mapped and modeled with electromagnetic techniques. Three of the twelve holes drilled by BHP Billiton in 2016 targeted VTEM anomalies; all three intersected copper mineralization, including:
Aston Bay believes the Storm Copper project holds significant potential for further development, and is also indicates the potential for other mineralized zones concealed in the subsurface elsewhere on the property.
Aston Bay’s 2017 Geophysical Program
A property-wide Falcon Plus Airborne Gravity Gradiometry survey was conducted by CGG Multi-Physics. The new high-resolution survey was completed over two large blocks within the Nunavut Property area and acquired a total of 15,327 line-kilometres of data at a line spacing of 200m (Figure 1). The Property is underlain mainly by very shallow-dipping Paleozoic carbonate strata. The survey was designed to detect horst-graben features indicative of potentially favourable “structural plumbing” for stratiform base metal mineralization, as well as detection of blind, sub-surface mineralization within the carbonate strata.
Key areas covered by the survey include the Storm Copper prospect and Seal Zinc deposit in the northern block, and the Typhoon Zinc prospect and nearby target areas in the south. All three areas returned strong gravity responses that were evaluated in detail by the Company’s geological and geophysical team prior to selection of diamond drill targets for the 2018 summer field program currently underway.
The Storm Copper prospect and Seal Zinc deposit occur with the northern survey block, characterized by a mainly east-west structural-stratigraphic grain. The Storm prospect comprises four high-grade, dominantly chalcocite occurrences associated with an east-west graben, partially delineated by prior diamond drilling (Figure 2). Copper-silver mineralization occurs both in close association with steeply dipping graben-bounding faults and as broadly stratiform mineralization lateral to the faults. The gravity survey returned strong responses along and within the graben, including three anomalies spatially associated with the 4100N, 2750N and 2200N occurrences; these anomalies extend well beyond the current drilling and are potential drill targets.
A fourth composite gravity anomaly occurs along the eastern extension of the Storm graben and is spatially associated with the Tornado copper occurrence, which to date has seen only two diamond drill holes. The gravity data suggest the presence of a second-order graben on the northern flank of the main structure, to date untested. A fifth gravity anomaly occurs along the northern flank of the Storm graben, west along strike from the large 4100N occurrence, and is also poorly tested to date.
The southern, relatively poorly known, part of the Nunavut Property is underlain by north-south trending Paleozoic carbonate and Precambrian basement strata, with several base metal showings and areas of geological complexity of interest to Aston Bay. The central part of this area was covered by the new survey, which outlined a strong north-south pattern of alternating gravity highs and lows, possibly indicative of favourable horst-and-graben structures. Further refinement of the geology and survey results will be completed to guide ongoing exploration.
VTEM and gravity gradiometry delineate copper mineralization at Storm
At Storm, hole AB18-09 targeted a 200 by 200 metre VTEM anomaly coincident with the western flank of a gravity anomaly, ~2.2 kilometres along strike from the 2750N zone (Figures 4 and 5). An historical drill hole, ST97-15, was drilled northwards to intersect local copper mineralisation (3m grading 1.5% Cu) on what Aston Bay’s modelling interpreted as the flank of the VTEM anomaly. Drill hole AB18-09 was drilled southwards and intersected significant copper in variably brecciated dolomudstone of the Allen Bay Formation from 39 to 83 metres downhole, primarily as fracture-controlled chalcocite with lesser to minor chalcopyrite, native copper and cuprite. Significant results within the 44m copper mineralized zone include:
These results demonstrate the continued effectiveness of VTEM, in conjunction with modelled gravity gradiometry, in detecting shallow copper sulphides. The remaining holes at Storm intersected local pyrite mineralisation, primarily in Allen Bay dolomudstones (Figures 5 and 6). The origin of these targeted gravity gradiometry anomalies remains unclear: variations in bulk rock density, topography and depth to target are possible explanations being investigated in advance of targeting and drill planning for the 2019 season. Density data obtained from this year’s core drilling will be instrumental in improving the targeting. Numerous gravity targets in the vicinity of the ~5km-long Storm graben remain untested, and drilling to date has been shallow relative to the prospectivity for stratiform mineralisation at depth.
Aston Bay’s 2018 Drill Program
Aston Bay’s 2018 drill program consisted of 3,135 metres of drilling over a total of nine drill holes targeting high-grade copper mineralization in the vicinity of Storm Copper and adjacent prospects, as well as targeting Polaris-type zinc mineralization at the Seal Zinc deposit and the Seal South prospect. The program comprised seven holes at the Storm copper prospect and two along strike from the Seal zinc deposit. Targets were based primarily on interpreted gravity gradiometry anomalies proximal to known mineralisation at Storm and Seal. Unusually challenging weather reduced the planned meterage for this drill season and several anomalies remain untested. The majority of the drill holes were relatively shallow at approximately 300m or less.
The 2021 EM surveys, commissioned by Aston Bay’s partner American West Metals Limited (“American West”), targeted extensions along strike and at depth of known mineralization, and followed up on previous geophysical anomalies. The surveys were completed in August 2021 to enhance existing targets and identify new potential drill targets ahead of the proposed 2022 drilling campaign. Previous EM surveys have successfully identified several strong conductive anomalies that are associated with known copper mineralization in the Storm Project area, including a large conductive anomaly associated with the high-grade 4100N Zone (intercepts include 67.6 m @ 1.33% Cu from 43.4 m in hole ST99-47).
The 2021 EM surveys confirmed the correlation between elevated conductivity and high-grade copper mineralization at the main Storm Copper showings, producing numerous shallow conductors coincident with drill confirmed mineralization. Known high-grade copper mineralization at Storm is hosted in gently dipping Paleozoic carbonate rocks, along and adjacent to the northern and southern margins of a west-northwest to east-northeast trending, ~1 km wide, fault-bounded valley or graben. Inversion and plate modelling of the EM data also defined multiple prospective conductors associated with the Storm graben within areas previously untested by drilling.
Seven untested shallow conductors of interest were identified (Figures 1 and 2; dark blue rectangles): two east along strike from the 2200N and 2750N zones, two west-northwest along strike from the 4100N Zone, one immediately west of the drilled area of the 4100N Zone conductive anomaly, one northeast of the 4100N Zone, and one northeast of the 3500N Zone. All seven untested shallow conductors are located along or in close proximity to the bounding faults of the Storm graben, in areas of elevated density identified by the 2017 airborne gravity gradiometry (AGG) survey (see Aston Bay News Releases dated November 30, 2017 and June 21, 2018). The conductors east of the 2200N and 2750N zone are also associated with significant copper in soil geochemical anomalies.
Seven untested deeper conductors of interest were also identified in the Storm Copper area (Figures 1 and 2; dark green rectangles). These broad, low-amplitude anomalies are generally at least partially associated with areas of elevated density identified by the 2017 AGG survey. Six of the seven anomalies are located along or adjacent to the bounding faults of the Storm graben. The geometry and mostly gentle dips of the modelled deep conductors suggest that they may be related to stratiform type targets, and may be indicative of traditional sedimentary type copper mineralization at depth. Given the highly resistive nature of the host dolomites, even subtle conductors are considered to be prospective when combined with coincident geochemical or airborne gravity anomalies.
BACKGROUND AND TECHNICAL DISCUSSION
Two distinct types of mineralization have been discovered at the Project to date (Figure 3).
The copper mineralization at Storm is chalcocite dominant and occurs as massive sulphides in breccias and veinlets within, or immediately adjacent to, sub-vertical faults. Although chalcocite (and chalcopyrite) are relatively low in conductance (when compared to some other sulphides), the dolomite host rocks generally have no EM response and therefore the contrast between the two is sufficient to allow EM to be an effective targeting tool.
The are no other conductive lithologies present in the Storm area, which increases the confidence that any anomalies may be related to copper mineralization.
The mineralization present within the Seal Deposit is stratabound where sphalerite occurs as massive sulphide replacement of the host dolomite and sandstone cements. Sphalerite and the host rocks generally have very low conductivity, and a test survey was completed to confirm if any contrasts between the different units were visible.
Success of Geophysical Surveys:
A number of geophysical techniques have been used to explore the Storm and Seal Project areas and wider tenure since the first copper and zinc discoveries in the early 1990’s.
Electromagnetics were proven to be an effective exploration tool when the Storm area was first surveyed with airborne EM in 1997. This survey determined a clear relationship between known, outcropping copper mineralization with newly identified EM anomalies. Subsequent higher resolution airborne and surface EM surveys, backed up by drilling, further confirmed this association.
The 2021 EM surveys utilised a time domain electromagnetic (TDEM) system featuring low noise / high power and were completed using a fixed conventional loop configuration. A total area of approximately 18km2 was completed for 945 stations, with a nominal station spacing of 100m at the Storm Copper prospect and 50m at the Seal Zinc deposit. Infills on a number of prospects at Storm were completed at 50m spacings.
The results of three EM survey lines over the high-grade zinc-silver Seal deposit indicated that the known mineralization at Seal is not visible to this particular EM system, and therefore no anomalies could be identified in the vicinity of the deposit. While this work does not preclude other EM systems effectively being used to explore around Seal, the nearby Tier 1 Polaris Zinc-Lead deposit was discovered using gravity surveys, and this will continue to be the preferred geophysical tool for testing the extensive Seal stratigraphic horizon.
Further ground EM surveys will be planned for the 2022 season to screen the Tornado and Blizzard areas. These areas lie east along strike from Storm and have existing copper in soil and gravity (AGG) anomalies.
Methodology and QA/QC
The 2021 Storm Project surface time domain electromagnetic (TDEM) survey was completed using a fixed conventional loop configuration (in and out of loop), with a nominal station spacing of 100 m with 50 m infills at the Storm Copper prospect, and 50 m at the Seal Zinc deposit. Storm loops 1 through 10 were sized 1,000 m by 1,000 m oriented at a 0° azimuth. Seal loop 11 was sized 400 m by 200 m oriented at a 45° azimuth. A Geonics TEM57 MK-2 transmitter with TEM67 boosters was used in conjunction with a portable Honda generator to produce a maximum output of 1.2 kW or 20 A or 60V. The Storm loops carried a current of 13-14 A and the Seal loop carried a current of 19.5 A. An ARMIT Mk2.5 sensor and EMIT SMARTem 24 receiver were used to measure and collect vertical (Z) and horizontal (X and Y) components of the B-Field and its partial derivative dB/dt. EMIT Maxwell software was used for QC, data processing, modelling, presentation and interpretation of the results. Seequent Montaj software was used for additional interpretation and to produce coloured maps.
Prior to the survey, the transmitter and generator were checked for maximum output using calibrated loads. Receivers were calibrated and synchronized to the transmitter prior to and during data acquisition. Polarity of the primary field components was checked and corrected, as necessary. All data were inspected, validated, and inspected for abnormal or problematic noise. No abnormal or problematic noise was observed.