Hera: Evidence for Multiple Mineralisation Events and Remobilisation in a Sediment-Hosted Au-Ag-Pb-Zn Deposit, Central New South Wales Australia.

The Hera Au-Ag-Pb-Zn deposit of central NSW, Australia with a total resource of 3.6 Mt @ 3.3g/T Au, 25g/T Ag, 2.6% Pb and 3.8% Zn occurs on the SE margin of the Cobar Basin. It is hosted by the shallow marine Mouramba Group and overlying turbiditic Amphitheatre Group. The siltstones comprise various mixtures of quartz, plagioclase, muscovite-phengite, biotite and clinochlore, along with relatively abundant accessory titanite and ilmenite. The deposit comprises a number of discrete lodes which are steeply west-dipping and strike NNW. Each lode has different abundances of the main ore minerals sphalerite, galena, chalcopyrite, pyrrhotite and gold. The North Pod and Far West lenses have the most diverse ore mineralogy in addition containing arsenopyrite, native silver, gudmundite, Ag-tetrahedrite, acanthite, dyscrasite, native antimony, nisbite and breithauptite. Electrum (continuous spectrum from Ag-rich to Au-rich) is associated with sulfides in the main ore lenses while native gold occurs in the host rocks along cleavages and away from the main ore. Most of the deposit has experienced greenschist facies metamorphism with pervasive green chlorite alteration, though the North Pod differs in being distinctly Ag and Sb rich and has reached at least amphibolite facies metamorphism with a garnet-wollastonite-vesuvianite-tremolite assemblage. Tremolite is relatively abundant throughout a number of the other lodes suggesting widespread low-T skarn alteration. Cross-cutting pegmatites comprise quartz, plagioclase (labradorite-andesine) and microcline. Scheelite is relatively abundant in the upper levels of the deposit, most commonly in cross-cutting quartz veins.