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


Harris, AC and Cooke, DR and Cuison, ALG and Groome, M and Wilson, AJ and Fox, N and Holliday, J and Tosdal, R, Geologic Evolution of Late Ordovician to Early Silurian Alkalic Porphyry Au-Cu Deposits at Cadia, New South Wales, Australia, Society of Economic Geologists Special Publications No. 23: Geology of the World's Major Gold Deposits and Provinces, Society of Economic Geologists, Inc, RH Sillitoe, RJ Goldfarb, F Robert and SF Simmons (ed), United States, pp. 621-643. ISBN 978-1-629493-12-1 (2020) [Research Book Chapter]

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Copyright 2020 Society of Economic Geologists, Inc.

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DOI: doi:10.5382/SP.23.30


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.

Item Details

Item Type:Research Book Chapter
Keywords:Cadia, porphyry, copper, gold, alkalic, exploration, Ridgeway
Research Division:Earth Sciences
Research Group:Geology
Research Field:Resource geoscience
Objective Division:Mineral Resources (Excl. Energy Resources)
Objective Group:Mineral exploration
Objective Field:Copper ore exploration
UTAS Author:Harris, AC (Dr Anthony Harris)
UTAS Author:Cooke, DR (Professor David Cooke)
UTAS Author:Cuison, ALG (Dr Ana Liza Cuison)
UTAS Author:Fox, N (Dr Nathan Fox)
ID Code:141187
Year Published:2020
Funding Support:Australian Research Council (IH130200004)
Deposited By:CODES ARC
Deposited On:2020-09-30
Last Modified:2020-10-16
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