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

Published online by Cambridge University Press:  21 January 2008

A. Maestro*
Affiliation:
Instituto Geológico y Minero de España, Ríos Rosas, 23, 28003 Madrid, Spain Departamento de Geología y Geoquímica, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 MadridSpain
J. López-Martínez
Affiliation:
Departamento de Geología y Geoquímica, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 MadridSpain
F. Bohoyo
Affiliation:
Instituto Geológico y Minero de España, Ríos Rosas, 23, 28003 Madrid, Spain
M. Montes
Affiliation:
Instituto Geológico y Minero de España, Ríos Rosas, 23, 28003 Madrid, Spain
F. Nozal
Affiliation:
Instituto Geológico y Minero de España, Ríos Rosas, 23, 28003 Madrid, Spain
S. Santillana
Affiliation:
Instituto Antártico Argentino, Cerrito 1248, 1010 Buenos Aires, Argentina
S. Marenssi
Affiliation:
Instituto Antártico Argentino, Cerrito 1248, 1010 Buenos Aires, Argentina

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 (σ3) 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 σ3 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 σ3 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.

Information

Type
Earth Sciences
Copyright
Copyright © Antarctic Science Ltd 2008

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