Impact of lower plate structure on upper plate deformation at the NW Sumatran convergent margin from seafloor morphology
|Author(s)||Graindorge D1, Klingelhoefer Frauke2, Sibuet Jean-Claude2, McNeill L3, Henstock T3, Dean S3, Gutscher M1, Dessa J4, Permana H5, Singh S6, Leau H7, White N8, Carton H6, Malod Jacques-Andre1, Rangin C9, Aryawan K10, Chaubey A, Chauhan A6, Galih D5, Greenroyd C11, Laesanpura A12, Prihantono J13, Royle G6, Shankar U14|
|Affiliation(s)||1 : UBO IUEM, UMR Domaines Ocean 6538, F-29280 Plouzane, France.
2 : IFREMER, Brest, France.
3 : Univ Southampton, Natl Oceanog Ctr, Southampton, Hants, England.
4 : UPMC, UMR Geosci Azur, Nice, France.
5 : Indonesia Inst Sci, Geotech Res Ctr, Earth Dynam & Geol Disaster Div, Bandung, Indonesia.
6 : Inst Phys Globe, Paris, France.
7 : Inst Polaire Paul Emile Victor IPEV, Brest, France.
8 : Bullard Labs, Cambridge, England.
9 : Coll France, CNRS, Aix En Provence, France.
10 : Marine Geol Inst, Energy & Earth Resources Dept, Bandung, Indonesia.
11 : Univ Durham, Durham, England.
12 : ITB, Bandung, Indonesia.
13 : Marine & Fishery Dept, Jakarta, Indonesia.
14 : NGRI, Hyderabad, Andhra Pradesh, India.
|Source||Earth and Planetary Science Letters (0012-821X) (Elsevier), 2008-11 , Vol. 275 , N. 3-4 , P. 201-210|
|WOS© Times Cited||54|
|Keyword(s)||Sumatra, Tectonic, Seafloor morphology, Accretionary wedge, Subduction|
|Abstract||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, all unusual style in accretionary wedges worldwide. The N-S elongated lineaments locally act as boundaries between zones with predominant seaward versus landward vergence.|