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Impact of lower plate structure on upper plate deformation at the NW Sumatran convergent margin from seafloor morphology

DRS at CSIR-National Institute of Oceanography

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Title Impact of lower plate structure on upper plate deformation at the NW Sumatran convergent margin from seafloor morphology
 
Creator Graindorge, D.
Klingelhoefer, F.
Sibuet, J-C.
McNeill, L.
Henstock, T.J.
Dean, S.
Gutscher, M-A.
Dessa, J.X.
Permana, H.
Singh, S.C.
Leau, H.
White, N.
Carton, H.
Malod, J.A.
Rangin, C.
Aryawan, K.G.
Chaubey, A.K.
Chauhan, A.
Galih, D.R.
Greenroyd, C.J.
Laesanpura, A.
Prihantono, J.
Royle, G.
Shankar, U.
 
Subject plate tectonics
active margins
ocean floor
tectonics
 
Description 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) are presented. 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 (seawarddipping) 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.
 
Date 2008-11-25T09:33:39Z
2008-11-25T09:33:39Z
2008
 
Type Journal Article
 
Identifier Earth and Planetary Science Letters, vol.275; 201-210p.
http://drs.nio.org/drs/handle/2264/1500
 
Language en
 
Rights Copyright [2008]. All efforts have been made to respect the copyright to the best of our knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
 
Publisher Elsevier