HR: 1340h
AN: T43A-1101    [Abstracts]
TI: Strike-slip Tectonics in the Schouten Basin: Western Branch of the Bismarck Sea Seismic Lineation
AU: * Llanes Estrada, P
EM: pllanes@geo.ucm.es
AF: Dpto. Geodinámica, Universidad Complutense de Madrid, Fac. CC. Geológicas, Ciudad Universitaria, Madrid, 28040, Spain
AU: Hoffmann, G
EM: garyh@pmc.ucsc.edu
AF: Dept. of Earth Sciences, University of California, 1156 High st., Santa Cruz, CA 94064, United States
AU: Silver, E
EM: silver@pmc.ucsc.edu
AF: Dept. of Earth Sciences, University of California, 1156 High st., Santa Cruz, CA 94064, United States
AU: Day, S
EM: sday@pmc.ucsc.edu
AF: Dept. of Earth Sciences, University of California, 1156 High st., Santa Cruz, CA 94064, United States
AU: Olaiz Campos, A
EM: ajolaizc@geo.ucm.es
AF: Dpto. Geodinámica, Universidad Complutense de Madrid, Fac. CC. Geológicas, Ciudad Universitaria, Madrid, 28040, Spain
AB: The Schouten Basin is located offshore the north-western coast of Papua New Guinea, approximately between longitudes 144° and 145°. The major tectonic feature in the area is the Bismarck Sea Seismic Lineation (BSSL), a sinistral strike-slip fault that bounds the north side of the basin and separates the North and South Bismarck Sea Plates. We collected bathymetry and backscatter data in the Schouten Basin and elsewhere in the Bismarck volcanic arc in 2004 aboard the research vessel Kilo Moana. In the area of the Schouten Islands, the BSSL changes its orientation from WNW east of Wei Island (144°21.5) to ENE west of Wei. The predominant structural geometry is a pattern of in-line structures, where several faults are parallel to the strike- slip zone. This geometry could be a result of strain partitioning to accommodate oblique shortening. The fault zone crosses less than 2 km off Wei's south coast and has probably affected the island itself. Our data reveals a major contrast offshore north and south of Wei, with a well developed insular slope and apron on the north side, eroded by a radial system of submarine canyons, and an extremely steep and uncommon insular slope on the south side, that also lacks the presence of an insular apron. We suggest that this south part of the island has been cut off and displaced left-laterally by the BSSL a distance of 45 km. In addition to the main structural direction, approximately E-W, the other predominant direction is given by a set of NE-SW faults. The latter are controlling the orientation of a set of submarine canyons off-shore from the Sepik and the Ramu rivers. These faults may also control local volcanism through the alignment of seamounts.
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 8150 Plate boundary: general (3040)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting