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university of Provence - Aix-Marseille I |  |
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university of Provence - Aix-Marseille I | |
| HAL: insu-00354708, version 1 |
| DOI: 10.1016/j.epsl.2008.04.053 |
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| Earth and Planetary Science Letters 275, 3-4 (2008) 201-210 |
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| Impact of lower plate structure on upper plate deformation at the NW Sumatran convergent margin from seafloor morphology |
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David Graindorge 1Frauke Klingelhoefer 2 |
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| (2008-11-15) |
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| We present results from multibeam bathymetric data acquired during 2005 and 2006, in the region of maximum slip of the 26 Dec. 2004 earthquake (Mw 9.2). These data provide high-resolution images of seafloor morphology of the entire NW Sumatra forearc from the Sunda trench to the submarine volcanic arc just north of Sumatra. A slope gradient analysis of the combined dataset accurately highlights those portions of the seafloor shaped by active tectonic, depositional and/or erosional processes. The greatest slope gradients are located in the frontal 30 km of the forearc, at the toe of the accretionary wedge. This suggests that long-term deformation rates are highest here and that probably only minor amounts of slip are accommodated by other thrust faults further landward. Obvious N–S oriented lineaments observed on the incoming oceanic plate are aligned sub-parallel to the fracture zones associated with the Wharton fossil spreading center. Active strike-slip motion is suggested by recent deformation with up to 20–30 m of vertical offset. The intersection of these N–S elongated bathymetric scarps with the accretionary wedge partly controls the geometry of thrust anticlines and the location of erosional features (e.g. slide scars, canyons) at the wedge toe. Our interpretation suggests that these N–S lineaments have a significant impact on the oceanic plate, the toe of the wedge and further landward in the wedge. Finally, the bathymetric data indicate that folding at the front of the accretionary wedge occurs primarily along landward-vergent (seaward-dipping) thrusts, an unusual style in accretionary wedges worldwide. The N–S elongated lineaments locally act as boundaries between zones with predominant seaward versus landward vergence. |
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| 1: | Domaines Océaniques |
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Institut Universitaire Européen de la Mer (IUEM) – Université de Bretagne Occidentale [UBO] – Observatoire des Sciences de l'Univers – CNRS : UMR6538 |
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| 2: | IFREMER Centre de Brest (IFREMER) |
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Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) |
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| 3: | National Oceanography Centre |
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Univesity of Southampton |
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| 4: | Géoazur (GEOAZUR) |
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Université Nice Sophia Antipolis [UNS] – CNRS : UMR6526 – Institut de recherche pour le développement [IRD] – Observatoire de la Côte d'Azur – INSU – Université Pierre et Marie Curie [UPMC] - Paris VI |
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| 5: | Earth Dynamics and Geological Disaster Division |
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Indonesia Institute of Sciences |
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| 6: | Institut de Physique du Globe de Paris (IPGP) |
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CNRS : UMR7154 – INSU – IPG PARIS – Université Pierre et Marie Curie [UPMC] - Paris VI – Université Paris VII - Paris Diderot – Université de la Réunion |
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| 7: | Institut Paul Emile Victor |
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Institut Paul Emile Victor |
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| 8: | Bullard Laboratories |
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Bullard Laboratories |
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| 9: | Centre européen de recherche et d'enseignement de géosciences de l'environnement (CEREGE) |
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CNRS : UMR6635 – Institut de recherche pour le développement [IRD] – INSU – Université de Provence - Aix-Marseille I – Université Paul Cézanne - Aix-Marseille III |
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| 10: | Marine Geological Institute |
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Energy and Earth Resources Department |
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| 11: | National Institute of Oceanography |
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National Institute of Oceanography |
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| 12: | Durham University |
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Durham University |
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| 13: | ITB |
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ITB |
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| 14: | Marine and Fish Department |
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Marine and Fish Department |
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| 15: | NGRI |
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NGRI |
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| subject | : | Sciences of the Universe/Earth Sciences/Geophysics Physics/Physics/Geophysics Environmental Sciences/Global Changes |
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| subduction – accretionary wedge – seafloor morphology – tectonic – Sumatra |
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| Attached file list to this document: | |||||
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| insu-00354708, version 1 | |
| http://hal-insu.archives-ouvertes.fr/insu-00354708 | |
| oai:hal-insu.archives-ouvertes.fr:insu-00354708 | |
| From: Dominique Gac | |
| Submitted on: Friday, 18 February 2011 17:30:46 | |
| Updated on: Monday, 21 February 2011 11:18:33 | |
