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Regional Crustal Setting of Iron Oxide Cu-Au Mineral Systems of the Olympic Dam Region, South Australia: Insights from Potential-Field Modeling

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Direen, NG and Lyons, P (2007) Regional Crustal Setting of Iron Oxide Cu-Au Mineral Systems of the Olympic Dam Region, South Australia: Insights from Potential-Field Modeling. Economic Geology, 102. pp. 1397-1414. ISSN 0361-0128

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Abstract

Detailed analysis and modeling of regional gravity and magnetic data from the Stuart Shelf around the
Olympic Dam iron oxide copper-gold (IOCG) deposit, constrained by geologic observations obtained from
deep drill cores, show that the eastern Gawler craton basement at 1.61 to 1.59 Ga consisted of an Archean core
with two sequences of successively younger supracrustal rocks stepping out eastward from it. These were overprinted
by the tectonothermal Hiltaba event. Forward models of potential-field data show no convincing evidence
for the presence of widespread mafic rocks or extensional basin systems developed immediately prior to,
or during, IOCG mineralization. The high intrusive level and sill-like geometry of Hiltaba Suite plutons emplaced
immediately prior to IOCG mineralization is difficult to explain in terms of a genetic association with a
dominantly extensional tectonic setting. Instead, the tectonic setting inferred from the basement architecture
during mineralization is one of low-strain shortening, consistent with regional field observations. A case can be
made for intrusion of the Hiltaba Suite in localized accommodation zones in an overall orogenic setting.
This style of low-strain shortening (<10%) is consistent with maximum rates and volumes of fluid flow in the
upper crust, and access of these fluids to a variety of basement rock types to buffer metal-scavenging fluids.
This fluid-driving mechanism does not necessitate a role for regional mafic magmatism and volcanism in the
formation of IOCG deposits. Modeling of regional gravity and magnetic data is generally applicable to exploration
for IOCG systems, and other mineral systems, in covered terranes that have distinctive geophysical signatures
resulting from fluid–wall-rock redox geochemical reactions.

Item Type: Article
Journal or Publication Title: Economic Geology
Page Range: pp. 1397-1414
ISSN: 0361-0128
Additional Information:

©2007 Society of Economic Geologists, Inc.

Date Deposited: 07 Sep 2010 02:35
Last Modified: 18 Nov 2014 04:12
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