Australian copper explorer American West (ASX: AW1, FRA: R84) has once again impressively confirmed the efficiency of geophysical methods as an aid to exploration on its Storm Copper Project in Nunavut on Somerset Island with a deep diamond drill hole on the Cyclone Deeps target.
As predicted by the data from the airborne Mobile MagnetoTellurics (MMT) survey, drill hole ST25-02 – also the first diamond drill hole of the current season – intersected an approximately 47-meter thick horizon with sediment-hosted copper mineralization at a depth between 284 and 319 meters and 368 and 380 meters.
The geologists had specifically targeted the Allen Bay host horizon within the Central Graben. The type of mineralization and the stratigraphic location of ST25-02 are visually very similar to the mineralization observed at the edges of the Cyclone deposit. Due to the similarities, the geologists suspect that the new discovery could be a continuation of the mineralization shifted into the depths, which has already been found on the Cyclone target.
American West Expects Analysis Results in a few Weeks
The type of mineralogy has typical characteristics for sedimentary copper deposits and the thickness of the intersection is interpreted to mean that the company may be on the edge of another large copper deposit. The detailed evaluation of these sections in the laboratory is expected in four to six weeks.
Dave O’Neill, Managing Director of American West Metals, commented: “Phase 1 of the MMT survey was completed over the Midway, Storm and Tornado areas. The initial data and preliminary results have revealed a number of large, conductive anomalies in favorable geological and structural locations. Significantly, the conductivity of the anomalies is very similar to that of the high-grade copper zones within the Cyclone deposit, suggesting that the anomalies may be associated with copper sulfide accumulations.”
The airborne Mobile MagnetoTellurics (MMT) survey has already identified several new copper targets at the beginning of the drilling season. The measurements were completed along the Midway-Storm-Tornado corridor and provided encouraging preliminary results. Five additional, large and favorably located conductive features were identified at an interpreted depth of 50 m and 350 m. A number of kilometer-scale conductive anomalies were identified in the deeper, low-frequency data, which were interpreted at a depth of more than 350 m. To date, approximately 1,320 line kilometers have been flown, with detailed data processing, interpretation and 3D modeling underway.
MMT uses the energy of natural sources to capture a broader spectrum of EM frequencies than the techniques previously used at Storm. The survey was developed to highlight more subtle/relative contrasts between the host rock and potential accumulations of conductive material (i.e. metal-containing sulfide) with improved spatial and depth resolution. This can be very useful in delineating deeper (>200 m) copper sulfide deposits at Storm, where the resistant host rock causes a signal-to-noise ratio that decreases with depth (and less confidence in the interpretation) in historical geophysics.
The preliminary data has been received and has identified six strong and large conductive features within the higher frequency dataset (anomalies A1-A6, interpreted 350m depth – Figure 5).
American West Has Already Completed 12 RC Drill Holes
RC drilling on the project is also progressing well, with 12 boreholes completed to date. These first boreholes are used to test resource upgrades and high-level exploration targets in the Storm area. The drill rig will soon move on to other regional exploration targets. Of the 12 RC boreholes, 7 boreholes were completed in the Thunder, Lightning Ridge and Corona deposits to upgrade the resource category.
In addition, 2 boreholes were completed to test for shallow resource expansions in the south of the Cyclone deposit and 2 exploration boreholes in The Gap and Southern Graben areas. Reverse circulation drilling (RC drilling) will continue with a pipeline of high-priority geophysical, exploration and resource expansion targets. Samples for 11 of the first RC boreholes were sent to the laboratory for analysis and are expected in the next 4-6 weeks. The unsampled historical diamond drill holes on the Tornado and Midway prospects were sampled and sent to the laboratory for analysis.
