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Full-fit reconstructions of the southern Australian margin and Antarctica – implications for correlating geology between Australia and Antarctica

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Williams, SE and Whittaker, JM and Muller, RD (2012) Full-fit reconstructions of the southern Australian margin and Antarctica – implications for correlating geology between Australia and Antarctica. In: Eastern Australasian Basins Symposium IV, 10-14 September 2012, Brisbane, QLD.

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Abstract

The sedimentary basins along the southern Australian and
conjugate Antarctic margins formed as a result of Mesozoic
rifting. A number of alternative models have been proposed for the
pre-rift configuration of Australia and Antarctica. They differ both
in how tight the fit between these continents is, and in the lateral
juxtaposition of the two continents, ie. some reconstructions place
Australia further to the east, relative to a fixed Antarctica, than
others. The continuity of comparable geological terranes, surfacemapped
shear-zones, and geophysical signatures (e.g. magnetic
anomalies) between Australia and Antarctica within Gondwana
has implications for assessing these different reconstruction
models.
To investigate this issue, we tested a range of scenarios for
the full-fit configuration of Australia and Antarctica. In the light
of palinspastic reconstructions of the extended continental crust
within each margin, we investigate how different reconstruction
models reconcile geological and geophysical signatures from the
conjugate plates. We find that a model that matches the Leeuwin
Fracture Zone (in the Australian margin) with the Vincennes
Fracture Zone (in the Antarctic margin) reconciles Proterozoic
structures previously correlated between the continents based on
their geological similarity. These include rocks from the Albany-
Fraser orogeny, and the Kalinjala mylonite zone and Mertz shear
zones. This model also reconciles the constraints from palinspastic
reconstruction of Mesozoic extension better than models
that place Australia further east or west relative to Antarctica
within Gondwana. This model does not produce a postulated
alignment between the Darling Fault in Western Australia and
the Denman Glacier in Western Wilkes Land. The preferred fullfit
reconstruction model, together with other evidence from the
early breakup history between the Australian and Antarctic plates,
suggests that the overall opening direction between the two
continents was broadly NNW-SSE, but this includes phases of N-S
and NW-SE–directed extension.

Item Type: Conference or Workshop Item (Paper)
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Copyright 2012 PESA

Date Deposited: 27 Aug 2013 00:09
Last Modified: 18 Nov 2014 04:53
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