Evolution of the Great Australian Bight, Southern Australian Passive Margin, from Integrated Geophysical Studies  

Authors / CoAuthors

Ball, P. | Ebinger, C. | Trifonova, P. | Eagles, G. | McClay, K. | Totterdell, J.

Abstract

Existing models for the evolution and break-up of weakly magmatic passive margins have been derived largely from observations of the North Atlantic margins. It is therefore unknown whether the observations from the Iberian margins are unique and site specific. Studies of Australo-Antarctic margins provide a broader spectrum for the development of conceptual models of the formation of weakly magmatic passive margins. Weakly magmatic passive margins record large amounts of extensional strain prior to breakup, but the role of magma intrusion and the along-strike variability of strain remain poorly understood. We re-evaluate existing onshore and offshore gravity, magnetic, seismic reflection, and well data from the Australo-Antarctic margins to probe the evolution of along-axis segmentation during progressive stages of rifting through to breakup and the onset of seafloor spreading. Our integrated plate reconstruction and geodynamic model for the break-up of the Australian-Antarctic conjugate margin provides a regional framework for analyses of continental breakup in weakly magmatic rift systems. The southern Australian margin evolved through at least two distinct phases of extension, but the timing of the phases was diachronous along the length of the rift: 1) strain concentrated along large offset border faults now located beneath the continental shelf break; 2) localisation of strain to a narrow zone of incipient break-up. Minor extrusive magmatism occurred only during the second rifting stage and within ~10 My prior to the first well-defined seafloor spreading anomaly.

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nonGeographicDataset

eCat Id

68817

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• External PublicationScientific Journal Paper

( Theme )

• continental margins

( Theme )

• geophysics

( Theme )

• plate tectonics

( Theme )

• marine

• AU-SA

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

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2009-04-16T00:00:00

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Australian Government Security ClassificationSystem    

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Creative Commons Attribution 4.0 International Licence    

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