Western Mines Group intersects copper-zinc at Mulga Tank project
Copper and zinc mineralisation was observed in the final hole of a 10-hole program totalling 3,990m.
Western Mines Group (ASX: WMG) has intersected significant copper-zinc mineralisation in diamond drilling at the Mulga Tank nickel-copper-PGE (platinum group elements) project in Western Australia.
The 10-hole program totalled 3,990m and was designed to test a range of geological and geophysical exploration targets around the Mulga Tank Ultramafic Complex.
The final hole was drilled to test the up-dip component of the NW3 conductor in the Panhandle area, which is a channel-like feature of the Mulga Tank intrusion that extends to the northwest.
It intersected significant copper-zinc mineralisation within a black shale unit containing extensive banded sulphides (25%-35% sulphide, pyrite-pyrrhotite-chalcopyrite) between 110m to 134m depth.
While the sulphides likely explain the modelled up-dip component of the electromagnetic (EM) anomaly in the area, they were encountered at much shallower depths than Western Mines anticipated.
Spot readings
Numerous spot pXRF (portable xray fluorescence) readings in excess of 1% copper were observed in two horizons down the hole, with a mean average of 0.8% copper for eight readings between 110.5m and 113m and a mean average of 1.3% copper for eight readings between 128.5m and 130.5m.
Anomalous zinc readings grading up to 1.8% were also associated with the copper results.
As the hole did not test the main core of the modelled NW3 conductor, Western Mines said the sulphide-rich unit may extend for considerable strike and depth.
Western Mines said this would likely be the distal flank of the Panhandle channel and would lead to a revised interpretation of the area, with the absence of the secondary north-south trending channel.
Geological model
Managing director Caedmon Marriott said the final hole did not encounter komatiite ultramafic as predicted by the company’s geological model, though it did grade into high magnesium oxide basalt and possible komatiite at the end of hole.
“While this hole was the only one in this program to not fit our geological model, it is certainly a very interesting result to encounter significant copper-zinc sulphide mineralisation at shallow depths,” he said.
“The core of the EM anomaly was not drilled and this sulphide unit could be quite extensive.”
Mr Marriott said the mineralisation was likely associated with late-stage hydrothermal fluids around the complex, with the geological environment possibly suggesting nearby volcanogenic massive sulphide-style deposits.