The Neoproterozoic Havieron Au-Cu Breccia, Paterson Province, Western Australia

Abstract

The Neoproterozoic Havieron Au-Cu deposit is a recently discovered blind polymetallic breccia lying beneath 420 m of postmineral, Permian sedimentary rocks in the Au-Cu-rich Paterson province of Western Australia. Located approximately 45 km east of the large Telfer Au-Cu deposit, Havieron has a horizontal footprint of approximately 800 × 500 m and extends over 1.2 km vertically below the unconformity. The multiphase Havieron Breccia Complex is hosted in thinly laminated clastic and calcareous sedimentary rocks of the Neoproterozoic Malu Formation that forms the SW-dipping limb of a NE-verging anticline. The breccia is spatially associated with a suite of high-Mg tholeiitic basalt and minor granitic intrusions.

Exploration drilling has defined a mineral resource of 7.0 Moz Au and 275 kt Cu (https://www.greatland.com.au/assets/havieron/) contained largely within a part of the breccia named the Crescent zone. This part of the breccia contains semimassive to massive pyrrhotite-chalcopyrite-calcite-quartz in replacement bodies and in breccia cement located at the southeastern contact of the breccia complex, spatially associated with now-brecciated mafic intrusions. The breccias have crackle, jigsaw, and open-space textures with angular clasts as well as locally wispy mafic clasts. Sulfide minerals, along with calcite, actinolite, biotite, and quartz, cement the breccia. The upper few hundred meters of the breccia are overprinted by a chlorite-illite assemblage with pyrite, sphalerite, and galena. Gold and Cu are associated with anomalous lithophile (Bi, W, and Sn) and siderophile (Ni and Co) elements. Available timing constraints for Havieron, coupled with the Au-Cu-Bi-W-Sn-Ni-Co silicate alteration assemblage, suggest a magmatic association for the deposit and its membership within the spectrum of reduced intrusion-related gold systems deposits found in the Paterson province.