GreenTech Metals’ recent downhole electromagnetic (DHEM) survey at its Whundo project in Western Australia’s Pilbara region has identified a big conductor plate measuring 400m long and between 50m and 100m wide at its Shelby target.
Shelby’s recent life as zone of specific interest began with Fox Resources’ geophysical work in 2006, which picked up a deep conductor associated with a weak magnetic response, about 500m north of the old Whundo open pit. Fox’s follow-up drilling under Shelby bored through 11.25m going 1.6 per cent copper from 391.25m depth including 5.8m running 2.4 per cent copper from 391.25m.
Further drilling by GreenTech two years ago intercepted 14m at 0.5 per cent copper from 417m including the last 3m of that hit running 1.3 per cent copper. Other attempts to drill the company’s previous EM target were frustrated by excessive hole deviation.
GreenTech says it is uncertain if the new conductor represents the same mineralisation as that which was successfully intercepted in a previous drillhole, or if it is a separate deeper zone of mineralisation. However, it is encouraged by the stronger conductor response of 15,000 Siemens from the latest DHEM survey, which distinguishes it from the previous conductor signals.
The first of those ran a relatively weak 1500 to 2500 Siemens, while the second response ran between 5000 and 10,000 Siemens.
Additionally, the latest strong DHEM response was obtained from the most recent, albeit deviated, hole that runs west away from and about 100m deeper (to 648m) than the previous holes. It is also well away from the respective mineral intercepts, so the hole ended up being of considerable value in the end and turned out to be in a perfect location to deploy the DHEM.
A further pointer to the possibility of the new response representing a different conductor is that while it also dips westward at much the same angle as the previous interpretations, it is a few degrees flatter, ranging from between 100m and 200m deeper and extending along strike for about 400m.
It is possible that the overall dip trend shown by the three conductor plates could be signalling a gentle flattening of the mineralisation with increasing depth.
GreenTech Metals executive director Tom Reddicliffe said: “We are excited to see such a large conductor materialise at depth at our Shelby target. This is exactly the scale of anomaly that we are targeting at Whundo which has the potential to significantly increase our copper resources.”
In other work, both the company’s Ayshia and Austin targets were drilled in the most recent program and DHEM surveys were also run on those holes, so there could be more encouraging responses to come.
GreenTech is now awaiting the pending analytical results and the geophysical interpretations of the DHEM surveys from Austin and Ayshia before planning a new drilling program, which will also include further testing of Shelby now that there is a healthy-looking conductor to sink the bit into.
The company has all of its required work programs and heritage clearances in hand, enabling it to move quickly on to its next round of drilling as soon as it can line up a rig.
And with Shelby now a definite target that has thrown up three conductor plates in the same general zone and showing increasing intensity with depth, GreenTech is keen to get started as soon as possible.
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By Doug Bright
