Geodynamic implications of the Cenozoic stress field on Seymour Island, West Antarctica

Abstract Palaeostress inferred from brittle mesostructures in Seymour (Marambio) Island indicates a Cenozoic to Recent origin for an extensional stress field, with only local compressional stress states. Minimum horizontal stress (σ 3 ) orientations are scattered about two main NE–SW and NW–SE modes...

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Bibliographic Details
Published in:Antarctic Science
Main Authors: Maestro, A., López-Martínez, J., Bohoyo, F., Montes, M., Nozal, F., Santillana, S., Marenssi, S.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 2008
Subjects:
Geology
Ecology, Evolution, Behavior and Systematics
Oceanography
Antarctic
The Antarctic
Antarctic Peninsula
Weddell Sea
West Antarctica
Scotia Sea
Weddell
Seymour
Seymour Island
Marambio
Larsen Basin
Antarc*
Antarctic Science
Antarctica
Online Access:http://dx.doi.org/10.1017/s0954102007000892
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102007000892
Description
Summary:Abstract Palaeostress inferred from brittle mesostructures in Seymour (Marambio) Island indicates a Cenozoic to Recent origin for an extensional stress field, with only local compressional stress states. Minimum horizontal stress (σ 3 ) orientations are scattered about two main NE–SW and NW–SE modes suggesting that two stress sources have been responsible for the dominant minimum horizontal stress directions in the north-western Weddell Sea. Extensional structures within a broad-scale compressional stress field can be linked to both the decrease in relative stress magnitudes from active margins to intraplate regions and the rifting processes that occurred in the northern Weddell Sea. Stress states with NW–SE trending σ 3 are compatible with back-arc extension along the eastern Antarctic Peninsula. We interpret this as due to the opening of the Larsen Basin during upper Cretaceous to Eocene and to the spreading, from Pliocene to present, of the Bransfield Basin (western Antarctic Peninsula), both due to former Phoenix Plate subduction under the Antarctic Plate. NE–SW σ 3 orientations could be expressions of continental fragmentation of the northern Antarctic Peninsula controlling eastwards drifting of the South Orkney microcontinent and other submerged continental blocks of the southern Scotia Sea.

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