Summary:
The Dugald River style of mineralisation is a sedimentary and shear hosted base metal deposit. The main sulphides are sphalerite, pyrite, pyrrhotite and galena with minor arsenopyrite, chalcopyrite, tetrahedrite, pyrargyrite, marcasite and alabandite.
The deposit is located within a 3km-4km along strike north-south trending high strain domain named the Mount Roseby Corridor and is hosted by steeply dipping mid Proterozoic sediments of the Mary Kathleen Zone in the Eastern Succession of the Mount Isa Inlier. The host sequence is composed of the Knapdale Quartzite and the Mount Roseby Schist Group (which includes the Hangingwall calc-silicate unit, the Dugald River Slate and the Lady Clayre Dolomite). The sequence is an interbedded package of greenschist to amphibolite grade metamorphosed carbonate and siliclastic lithologies.
The main Dugald River lode is hosted within a major N-S striking steeply west dipping shear zone which cross cuts the strike of the Dugald River Slate stratigraphy at a low angle. All significant zinc-lead-silver mineralisation is restricted to the main lode. Lesser-mineralised hanging wall and footwall lenses are present.
The five main types of mineralisation style recognised at Dugald River are sulphide stringer, banded ore, slatey breccia, pyrrhotite-slatey breccia and massive breccia.
The geometry of the deposit consists of the boudinaged main lens, which pinches and swells in thickness along strike and to depth. It is recognised that the previously modelled hangingwall and footwall domains (1A, 2, 3, 4 and 5) are part of the main lens which anastomoses, splits and merges. All zinc and associated lead-silver mineralisation are governed by this geometry.
The mineralogy of the Dugald River lode is typical of a shale-hosted base metal deposit. The gangue within the lode is composed of quartz, muscovite, carbonates, K-Feldspar, clays, graphite, carbonaceous matter and minor amounts of calcite, albite, chlorite, rutile, barite, garnet, and fluorite.
The mineralised zone extends approximately 2.4km in strike length and up to 1.4km down-dip.
Dimensions
The Dugald River lode is hosted within a major N-S striking steeply west dipping shear zone which cross cuts the strike of the Dugald River Slate stratigraphy at a low angle.
The strike length of mineralisation is approximately 2,400 m. Dip varies between 85° and 40° to the west.
The true thickness of the majority of the Mineral Resource is between 3 m and 30 m with the thickest zones occurring to the south.
The mineralisation is open at depth. The deepest drill intersection of mineralised material is about 1,140 m below the surface.