Drilling by QMines (ASX: QML) at the historic Mt Chalmers copper-gold project in Queensland has intersected new mineralisation outside of the current resource envelope.
The new drillholes were designed to provide a better understanding of the geological interpretation of the Mt Chalmers ore body and grow the resource.
The company confirmed that visible chalcopyrite in stringer veins was intersected in all drillholes outside the existing resource envelope.
An upgrade to the Mt Chalmers resource is expected later this year.
Mt Chalmers is a high-grade copper-gold mine which operated for 84 years before its closure in 1982.
During this time, the mine produced a total 1.2 million tonnes at 2% copper, 3.6 grams per tonne gold and 19g/t silver.
It has a current inferred resource of 3.9Mt at 1.15% copper, 0.81g/t gold and 8.4g/t silver.
The Mt Chalmers system contains copper, gold, zinc, lead and silver mineralisation and is recognised as one of the world’s highest-grade gold volcanogenic massive sulphide (VHMS) mineral systems.
Mt Chalmers mineralisation
The Mt Chalmers mineralisation is situated in the early Permian Berserker Beds, which occur in the 120km long Berserker Graben structure, bounded on the east side by the Tungamull Fault and on the west by the Parkhurst Fault.
The Berserker Beds lithologies consist of acid to intermediate volcanics, tuffaceous sandstone and mudstone, with generally flat-lying, locally-folded strata.
The most common lithotypes are rhyolitic and andesitic lavas, ignimbrites or ash flow tuffs with numerous breccia zones.
The rocks of the Berserker Beds are weakly metamorphosed and have not been subjected to major tectonic disturbance, except for normal faults and localised high strain zones that are interpreted to have developed during and after basin formation.
Recent geological work by Queensland’s Department of Natural Resources and Mines placed the volcanic and sedimentary units of the prospective Chalmers formation – which is the host unit to the Mt Chalmers copper-gold mineralisation – at the base of the Berserker Beds.
Soil sampling data recently digitised by QMines indicated the potential for the discovery of additional preserved VHMS systems in the region.
These soil anomalies appear to have geochemical and lithological similarities to Mt Chalmers.