Legend Mining Limited (ASX:LEG) is undertaking low-frequency EM survey work at Area D of the Rockford project in WA’s Fraser Range as the final step before beginning diamond drilling.
The low-frequency moving loop electromagnetic (LF-MLTEM) surveying is being carried out at the D5 conductor.
As well as assisting with diamond drill hold planning, this work is designed to better constrain and resolve this conductor.
D5 highest priority target
Of 17 conductors identified at Area D, extensive geophysical and geological analysis has determined the D5 conductor to be the highest priority target for nickel-copper sulphides.
Legend managing director Mark Wilson said, “This low-frequency EM survey is the final step before diamond drilling at Area D.
“The survey is expected to be completed by the end of September which will facilitate a mid-late October start for the diamond drill program.
“Meanwhile the regional aircore drilling is ongoing.”
Strong nickel prices
This work comes at a time of increased global interest in nickel owing to improved market fundamentals which are supporting strong prices.
As Rockford is also in the proven nickel ground of the Fraser Range as evidenced by the activity of Independence Group NL (ASX:IGO) and Creasy Group interests, Wilson is buoyant about the future for Legend.
The LF-MLTEM survey will involve four 3-kilometre lines spaced 200 metres apart and utilise a 200-amp transmitter with 200-metre x 200-metre loops.
Very low frequencies used
An initial frequency of 0.0625Hz, compared to conventional survey frequencies of 0.025-0.5 Hz, will be run with the capability to reduce the frequency even lower for increased definition if required.
D5 conductor was originally identified by MLTEM surveying and occurs near the SW hinge of a NE-SW trending synformal feature.
Aircore drilling immediately east of D5 increased the prospectivity of the feature with the intersection of magmatic nickel-copper-cobalt sulphides in several holes, including 14 metres at 0.37% nickel, 0.43% copper and 0.03% cobalt from 72 metres.
The LF-MLTEM technique is an extension of previous innovative EM surveying completed by Legend over the Rockford project.
It will use very low frequencies to provide detailed information on the character and possible source of the conductor.
Identifying conductive bodies
The aim of the survey is to identify conductive bodies related to massive nickel-copper sulphide mineralisation, which are potentially masked or adjacent to conductors related to graphite ±barren sulphides known to occur at Area D.
Essentially, the better the EM response in late time, the greater the chance the feature may represent nickel-copper sulphide mineralisation.