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Cambrian palaeomagnetic data confirm a Natal Embayment location for the Ellsworth-Whitmore Mountains, Antarctica, in Gondwana reconstructions

Randall, Darren E.; Mac Niocaill, Conall. 2004 Cambrian palaeomagnetic data confirm a Natal Embayment location for the Ellsworth-Whitmore Mountains, Antarctica, in Gondwana reconstructions. Geophysical Journal International, 157 (1). 105-116. 10.1111/j.1365-246X.2004.02192.x

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Abstract/Summary

The Ellsworth-Whitmore Mountains (EWM) are one of five terranes that form West Antarctica. Constraining the positions of these terranes in pre-break up Gondwana is crucial to understanding the history of the palaco-Pacific Gondwana margin. We report the results of a detailed palaeomagnetic investigation of the EWM, which comprises some 150 sites in six formations, ranging in age from Cambrian to Permian. Five of the studied units yield only viscous remnant magnetizations of recent age, or unstable natural remanent magnetizations. The remaining unit, the mid-late Cambrian Frazier Ridge Formation, yielded stable magnetizations at 16 of 35 sites. This component passes a fold test at the 95 per cent confidence level, indicating that it pre-dates Permian deformation, and we argue that it is of primary origin. The resulting palaeopole (9degreesN; 293degreesE; A(95) = 5.1degrees) is in good agreement with two previously published palaeopoles from similarly aged rocks in the EWM. Collectively these data indicate that the EWM were located in the Natal Embayment prior to Gondwana break-up, and underwent 90degrees of anticlockwise rotation during break-up. All three studies, however, yield inclinations that are slightly too shallow when compared with coeval Gondwana reference poles.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1111/j.1365-246X.2004.02192.x
Programmes: BAS Programmes > Antarctic Science in the Global Context (2000-2005) > Antarctica in the Dynamic Global Plate System
ISSN: 0956-540X
NORA Subject Terms: Earth Sciences
Date made live: 25 Jan 2012 08:49
URI: http://nora.nerc.ac.uk/id/eprint/12353

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