Geology of the shear zone hosted Dugald River Zn-Pb-Ag deposit, Mt Isa Inlier, NW QLD.

Dugald River is a world-class deposit with a total Mineral Resource of 68 Mt @ 11.6 % Zn, 1.2 % Pb, and 26 g/t Ag. The deposit has experienced a protracted history of polyphasal folding, shearing, boudinage and brecciation with mineralisation governed by a prominent shear zone. This has caused the orebody to become attenuated that anastomoses, pinch and swells into a complex array of ore textures with varying sulphide distribution and alteration occurrence. The deposit is hosted within the Dugald River Slates and consists predominantly of sphalerite with a variable distribution of galena, silver and gangue pyrrhotite, pyrite and carbonate. The key ore texture types include transposed banded ore, milled breccias with massive sulphide matrix, sulphide bearing carbonate crackle breccias and lesser low-grade sphalerite to pyrrhotite-pyrite stringers. Chalcopyrite occurs in the hangingwall of the orebody within quartz vein breccia, with pyrrhotite-pyrite stringers and the brecciated margins of localised albitite. The Cu mineral inventory resource sits at ~10 Mt and is discontinuous due to data paucity but contains strategic value due to the association with Au, Co and Mo. The Dugald River Slates are enriched in K, Ba and Mn as widespread K-feldspar, hyalophane and manganiferous variants of carbonate, garnet and sphalerite. Carbonate and Fe-sulphides are extensive throughout the slates and are considered paragenetically pre-, syn- and post- mineralisation. The deformation history includes S1 preserved within altered porphyroblasts, which are aligned parallel to the pervasively developed S2 cleavage, whilst an S3 crenulation cleavage is localised to the hangingwall micaceous schists and mafic porphyry. Past research presents conflicting deposit origins from exhalative formation, to the structural modification of exhalative sulphides to a pure epigenetic origin post-dating peak metamorphism within the lithologically controlled shear zone. The deposit remains open along strike and at depth with significant opportunities for growth based on current orebody knowledge.Open-Access Online Publication: March 03, 202