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Geologic Evolution of Late Ordovician to Early Silurian Alkalic Porphyry Au-Cu Deposits at Cadia, New South Wales, Australia

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posted on 2023-05-22, 18:30 authored by Anthony HarrisAnthony Harris, David CookeDavid Cooke, Ana Liza CuisonAna Liza Cuison, Groome, M, Wilson, AJ, Fox, N, Holliday, J, Tosdal, R
The Cadia district of New South Wales contains four alkalic porphyry Au-Cu deposits (Cadia East, Ridgeway, Cadia Hill, and Cadia Quarry) and two Cu-Au-Fe skarn prospects (Big Cadia and Little Cadia), with a total of ~50 Moz Au and ~9.5 Mt Cu (reserves, resources, and past production). The ore deposits are hosted by volcaniclastic rocks of the Weemalla Formation and Forest Reefs Volcanics, which were deposited in a submarine basin on the flanks of the Macquarie Arc during the Middle to Late Ordovician. Alkalic magmatism occurred during the Benambran orogeny in the Late Ordovician to early Silurian, resulting in the emplacement of monzonite intrusive complexes and the formation of porphyry Au-Cu mineralization. Ridgeway formed synchronous with the first compressive peak of deformation and is characterized by an intrusion-centered quartz-magnetite-bornite- chalcopyrite-Au vein stockwork associated with calc-potassic alteration localized around the apex of the pencil-like Ridgeway intrusive complex. The volcanic-hosted giant Cadia East deposit and the intrusion-hosted Cadia Hill and Cadia Quarry deposits formed during a period of relaxation after the first compressive peak of the Benambran orogeny and are characterized by sheeted quartz-sulfide-carbonate vein arrays associated with subtle potassic, calc-potassic, and propylitic alteration halos.

Funding

Australian Research Council

AMIRA International Ltd

BHP Billiton Ltd

Newcrest Mining Limited

History

Publication title

Society of Economic Geologists Special Publications No. 23: Geology of the World’s Major Gold Deposits and Provinces

Volume

23

Editors

RH Sillitoe, RJ Goldfarb, F Robert and SF Simmons

Pagination

621-643

ISBN

978-1-629493-12-1

Department/School

School of Natural Sciences

Publisher

Society of Economic Geologists, Inc

Place of publication

United States

Extent

40

Rights statement

Copyright 2020 Society of Economic Geologists, Inc.

Repository Status

  • Open

Socio-economic Objectives

Copper ore exploration; Precious (noble) metal ore exploration

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