Crustal setting of iron oxide Cu-Au mineral systems of the Olympic Dam region, South Australia: Insights from potential-field data  

Authors / CoAuthors

Lyons, P. | Direen, N.G.

Abstract

Detailed analysis and modeling of regional gravity and magnetic datasets from the Stuart Shelf around the Olympic Dam iron oxide-copper-gold (IOCG) deposit, constrained by geological observations from deep drillcores, show that the eastern Gawler Craton at 1.61-1.59 Ga consisted of an Archean core with two volumes of supracrustal successions stepping out eastward from it. This pattern is consistent with that displayed on the Eyre Peninsula. Detailed models of potential-field data show no 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 geometry of Hiltaba Suite plutons emplaced immediately prior to IOCG mineralization is difficult to explain in terms of a genetic association with mantle plumes, continental extension, or rifting. Instead, the tectonic setting inferred from the basement architecture during mineralization is one of low-strain compression, based on geometric considerations. A case can be made for mild extension in a localized accommodation zone during emplacement of the Hiltaba Suite and Gawler Range Volcanics, in an overall orogenic setting with northwest-southeast directed tectonic transport in present coordinates. An IOCG minerals system produced during low-strain compression 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 require, or implicate, a genetic role for regional mafic magmatism and volcanism synchronous with IOCG mineralization. The approach used in this study is generally applicable to exploration for IOCG systems, and other mineral systems in covered terranes that have distinctive geophysical signatures resulting from redox fluid-wallrock geochemical reactions.

Product Type

nonGeographicDataset

eCat Id

63710

Contact for the resource

Keywords

• External Publication

( Theme )

• geophysics

( Theme )

• mineral exploration

( Theme )

• economic geology

( Theme )

• gravity

( Theme )

• magnetics

• AU-SA

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

Publication Date

2005-08-17T00:00:00

Creation Date

Security Constraints

Australian Government Security ClassificationSystem    

Classification - unclassified

Legal Constraints

Creative Commons Attribution 4.0 International Licence    

Access - restricted

Use - license

Status

Purpose

Maintenance Information

unknown

Topic Category

geoscientificInformation

Series Information

Lineage

Unknown

Parent Information

Extents

[-32.58, -29.88, 135.96, 138.22]

Reference System

Spatial Resolution

Service Information

Associations

Downloads and Links

Source Information

Source data not available.