M3 Mining Limited (ASX: M3M) has identified a highly conductive body north of the historic Victoria Copper Minewith results from a FLE survey of the Victoria Bore Copper Project (Victoria Bore or the Project), located approximately 115km South of Onslow in WA.
In June 2022, a Fixed Loop Electromagnetic (FLEM) geophysical survey was completed over the highly prospective Victoria Bore area. The survey utilised SQUID sensor technology in order to delineate conductivity beneath the previously intersected shale. It was successful in identifying the presence of a strong conductor on the northern boundary of the survey.
The newly identified conductor coincides with a termination structure interpreted from government magnetics data. It is an order of magnitude stronger than the anomalies previously intersected by drilling at the Victoria Bore mine.
The EM response of this zone is interpreted to represent an accumulation of semi-massive to massive sulphides, potentially associated with base metal mineralisation.
Since the maiden drilling programme, the M3 team has been eagerly awaiting the results and analysis from the SQUID FLEM survey,” Executive Director, Simon Eley, said.
“We are excited to see that the survey has found a target that’s in close proximity to an interpreted regional structure. Conductive responses of this scale are particularly encouraging, due to the historic copper, lead, zinc and silver occurrences in the area and the previously intersected disseminated/matrix sulphides.
“We look forward to testing these targets with a follow-up drill program as soon as practicable.”
High Powered SQUID FLEM Survey
GAP Geophysics were engaged to complete a Fixed Loop Electromagnetic (FLEM) geophysical survey using two large-scale loops (600m x 400m), utilising highly sensitive equipment over the Victoria Bore area.
The survey lines were spaced at 100m, and stations spaced at 50m along the lines. The survey comprised of 280 individual station readings across a total of 13.2km. The FLEM survey was designed considering the presence of the previously intersected, weakly conductive shale.
By offsetting the transmitter loops and using the specialised SQUID sensor, the survey was able to identify strong conductive bodies in close proximity to the shale. Plate modelling reveals that the shale unit has a conductive level of ~250 Siemens (S) whilst the highly conductive target reads at ~5,000S. Three response channels have been used in the interpretation.
Channel 10 shows the early-time response and outlines the linear trend of the weakly conductive shale unit over the entire survey length. Channel 25 shows a medium-time response and indicates that the shale EM response increases in strength towards the north, due to higher conductivity and/or thickening.
Lastly, Channel 35 shows the late-time response which is where the strong conductive body is highlighted on the northern boundary of the survey.
Confirmation from the consultant geophysicist indicates that it is unlikely that a continuous shale could change conductivity levels from 250S to 5,000S over a distance of 400m. It is more likely that the strong conductor represents a discrete separate conductive body. The conductive source detected on the northern limit of the survey remains open to the north and trends adjacent to the NNW trending shale unit. It may be associated with an accumulation of semi-massive to massive sulphides. The presence of base metals in the Project area increases the chance of the new target hosting base metal mineralisation.
The new target aligns with the northern extent of a NW trending magnetic anomaly present in government magnetics data.
The magnetic trend appears to be terminated by a regional scale structure that is interpreted to trend approximately north-east. The combination of an interpreted regional scale structure, highly conductive body and regionally anomalous Cu, Pb, Zn and Ag is very encouraging for the discovery of a significant base metals deposit. The EM anomaly is located 400m north of VBRC001 which targeted a historical MLEM anomaly. At the planned target depth, VBRC001 intersected mostly shale as well as disseminated sulphides. Subsequently, a DHEM survey detected a discrete off-hole target up-dip to the east which could be a southern continuation of the highly conductive SQUID FLEM target.
Follow-up Drilling
The company is planning an expedited drill programme to test the high-priority conductor to the north. Based on the modelled plates, the planned programme expects to intercept the target as shallow as 200m below surface. The program will also test the exceptionally conductive (30,000S) smaller plate that was identified near VBRC001 in the DHEM survey.