HR: 14:55h
AN: T33E-06    [Abstracts]
TI: Morphotectonic, Morphometric, and Critical Taper Analysis of the Offshore Peruvian Continental Slope – Implications for Wedge Mechanics and Submarine Landscape Evolution
AU: * Kukowski, N
EM: nina@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Hampel, A
EM: andrea.hampel@ruhr-uni-bochum.de
AF: Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum, Universitätsstr. 150, Bochum, 44801, Germany
AU: Hoth, S
EM: shoth@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Norabuena, E O
EM: enorab@nazca.igp.gob.pe
AF: Instituto Geofisico del Peru, Calle Badajoz 169, Urb. Mayorazgo- IV Etapa, Lima, 3, Peru
AU: Bialas, J
EM: jbialas@ifm-geomar.de
AF: Leibniz-Institut für Meereswissenschaften IFM-GEOMAR, Wischhofstr. 1-3, Kiel, 24148, Germany
AB: We use new swath bathymetry data acquired during the RV Sonne cruise GEOPECO and complement them with swath data from adjacent regions to analyse the morphotectonics of the Peruvian convergent margin. The Nazca plate is not covered with sediments and therefore has a rough surface along the entire Peruvian trench. The styles of roughness differ significantly along the margin with linear morphological features trending in various directions, most of them oblique to the trench and roughness magnitudes of a few to several hundred meters. Oblique convergence and resulting strain partitioning cause a transtensional stress regime in the outer fore-arc. The lower slope is locally very rough and at the verge of failure throughout the entire Peruvian margin, as a result of subduction erosion causing the lower slope to oversteepen. Critical taper analysis is applied to the forearc wedge along several transects. Using curvature attributes to quantitatively examine the morphology in the Yaquina and Mendaña areas revealed that the latter shows a larger local roughness both seaward and landward of the trench however, the amplitude of morphological roughness is larger in the Yaquina area. We identified a 250 km² large slump on the Lima middle slope. Morphometric dating suggests an age of 74,500 years within 50% error and incision rates on the upper slope are between 0.1 and 0.3 mm per year suggesting that landscape evolution on the Peruvian submarine continental slope is similarly slow than that in the Atacama desert.
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 3070 Submarine landslides
DE: 8104 Continental margins: convergent
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting