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Flexural controls on late Neogene basin evolution in southern McMurdo Sound, Antarctica

Aitken, Alan R.A.; Wilson, Gary S.; Jordan, Thomas; Tinto, Kirsty; Blakemore, Hamish. 2012 Flexural controls on late Neogene basin evolution in southern McMurdo Sound, Antarctica. Global and Planetary Change, 80-81. 99-112. 10.1016/j.gloplacha.2011.08.003

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Abstract/Summary

The basins of southern McMurdo Sound have evolved under the influence of lithospheric flexure induced by the loads of the Erebus Volcanic Province. To characterise these basins, it is important to investigate the lithosphere's flexural properties, and estimate their influence on basin architecture and evolution. Seismic and gravity data are used to constrain 3D forward modelling of the progressive development of accommodation space within the flexural basins. Elastic plate flexure was calculated for a range of effective elastic thicknesses (Te) from 0.5 to 25 km using a spectral method. Models with low, but nonzero, Te values (2 km < Te < 5 km) produce the best fit to the gravity data, although uncertainty is high due to inaccuracies in the Digital Elevation Model. The slopes of flexural horizons revealed in seismic reflection lines are consistent with this, indicating a Te of 2 km to 5 km, although the depths to these horizons are not consistent, perhaps due to a northwards slope, or step, in the pre-flexural surface. These results indicate that the lithospheric strength of southern McMurdo Sound is significantly less than estimates of the regional average (Te ~ 20 km). This low strength may reflect the weakening effects of the Terror Rift, and perhaps also the Discovery Accommodation Zone, a region of major transverse faulting. A low Te model (Te = 3) for southern McMurdo Sound predicts the development of two discrete flexural depressions, each 2–2.5 km deep. The predicted stratigraphy of the northern basin reflects flexure due to Ross Island, predominantly erupted since ca. 1.8 Ma. The predicted stratigraphy of the southern basin reflects more gradual flexure from ca. 10 Ma to ca. 2 Ma, due to the more dispersed volcanoes of the Discovery subprovince. Collectively, these two basins have the potential to preserve a remarkable stratigraphic record of Antarctic climate change through the late Neogene.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.gloplacha.2011.08.003
Programmes: BAS Programmes > Polar Science for Planet Earth (2009 - ) > Environmental Change and Evolution
ISSN: 09218181
Additional Information. Not used in RCUK Gateway to Research.: Referred to by Alan R.A. Aitken, Gary S. Wilson, Tom Jordan, Kirsty Tinto, Hamish Blakemore Reprint of: Flexural controls on late Neogene basin evolution in southern McMurdo Sound, Antarctica Global and Planetary Change, Volumes 96–97, October–November 2012, Pages 9-22
Additional Keywords: flexure; Neogene; basin evolution; volcanic load; McMurdo Sound
NORA Subject Terms: Earth Sciences
Date made live: 18 Dec 2012 16:36 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/20845

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