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GEOREF RECORD

Porphyry Au-Cu mineralization controlled by reactivation of an arc-transverse volcanosedimentary subbasin

Nathan Fox, David R. Cooke, Anthony C. Harris, Dean Collett and Graeme Eastwood
Porphyry Au-Cu mineralization controlled by reactivation of an arc-transverse volcanosedimentary subbasin
Geology (Boulder) (July 2015) 43 (9): 811-814

Abstract

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.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 43
Serial Issue: 9
Title: Porphyry Au-Cu mineralization controlled by reactivation of an arc-transverse volcanosedimentary subbasin
Affiliation: University of Tasmania, Centre of Excellence in Ore Deposits, Hobart, Tasmania, Australia
Pages: 811-814
Published: 20150728
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 27
Accession Number: 2015-079085
Categories: Economic geology, geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., geol. sketch maps
S37°30'00" - S28°15'00", E141°00'00" - E153°30'00"
Secondary Affiliation: Newcrest Mining, AUS, AustraliaMacquarie Group, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201534
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