Authors / CoAuthors
Borissova, I. | Colwell, J. | Stagg, H.M.J.
Abstract
Deep-seismic data acquired by Geoscience Australia from the Naturaliste Plateau off southwest Australia in 1997, and from Bruce Rise on the margin of East Antarctica in 2001, allow direct comparison of these conjugate margins for the first time. Sampling has shown that the Naturaliste Plateau is at least partly of continental origin and composed of Proterozoic to Cambrian metamorphic rocks. A rift phase on the Naturaliste Plateau resulting in a series of predominantly E-W oriented grabens is estimated to have occurred in the Late Jurassic to earliest Cretaceous. Similar grabens are also present beneath the Bruce Rise. The Diamantina Zone, south of the Naturaliste Plateau, has been interpreted as a continent-ocean transitional zone with sampling indicating that the southernmost part is comprised of peridotite ridges. In contrast, to the north and northwest of Bruce Rise, the basement seismic character, and headwave velocities interpreted from sonobuoys, suggest that it is likely to be of oceanic origin. This crust lies about 2000 m deeper than the fast-spreading Eocene crust of the Australian-Antarctic Basin. Correlation of magnetic anomalies and the seismic character of the deep crust suggest that it formed either during an episode of Early Cretaceous seafloor spreading coincident with the opening of the Perth and Enderby Basins, rather than during the very slow spreading between Australia and Antarctica that started in the early Campanian. In either case, the breakup of the Naturaliste Plateau and the Bruce Rise appears to have been highly asymmetric with most of the extended continental or transitional crust being attached to the Australian margin.
Product Type
nonGeographicDataset
eCat Id
41497
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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- External PublicationAbstract
- ( Theme )
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- seismics
- ( Theme )
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- continental margins
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- AQ
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2003-01-01T00:00:00
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