Located in the accreted remnants of the Ordovician Macquarie Arc (Australia), Cadia East is the largest alkalic porphyry Au-Cu deposit currently known. The deposit is centered on a 2-km-long, northwest-trending volcanosedimentary subbasin, which was identified by mapping variations in the distribution and thickness of faulted sedimentary marker horizons. The normal faults that define the subbasin predate porphyry mineralization and are oriented parallel to a major arc-transverse lineament. Porphyry Au-Cu mineralization was controlled by reactivation of the subbasin during postorogenic extension as the Macquarie Arc was accreted to the Gondwana margin in the early Silurian. Dilation of the northwest-trending subbasin faults facilitated emplacement of alkalic porphyry dikes and associated sheeted quartz-sulfide veins that define the Cadia East orebody. During the middle Silurian, north-trending fault-bound marine basins buried Cadia East, significantly enhancing preservation of the ore system. These north-trending faults were optimally oriented for reactivation during Devonian east-directed compression, leaving the mineralized Cadia East volcanosedimentary subbasin largely intact. We identify the significance of reactivated premineralization structures within an arc-transverse lineament in controlling porphyry Au-Cu mineralization in a postsubduction setting. At Cadia East, the manifestation of such premineralization structures can be observed at regional, district, and deposit scales, and highlights the influence of preexisting crustal architecture on the structural character, geometry, and preservation potential of porphyry deposits throughout the arc life cycle.

Item Type:	Refereed Article
Keywords:	porphyry copper, alkalic porphyry, basin, faults, arc, gold
Research Division:	Earth Sciences
Research Group:	Geology
Research Field:	Resource geoscience
Objective Division:	Mineral Resources (Excl. Energy Resources)
Objective Group:	Mineral exploration
Objective Field:	Precious (noble) metal ore exploration
UTAS Author:	Fox, N (Dr Nathan Fox)
UTAS Author:	Cooke, DR (Professor David Cooke)
ID Code:	103093
Year Published:	2015
Web of Science® Times Cited:	13
Deposited By:	Centre for Ore Deposit Research - CODES CoE
Deposited On:	2015-09-21
Last Modified:	2017-10-30
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