HR: 0830h
AN: T31C-0859    [PDF]
TI: Continental Margin Tectonics Along the Convergent Plate Boundary of Central Chile
AU: * Weinrebe, W
EM: wweinreb@geomar.de
AF: GEOMAR, Wischhofstrasse 1-3, Kiel, 24148 Germany
AU: Ranero, C R
EM: cranero@geomar.de
AF: GEOMAR, Wischhofstrasse 1-3, Kiel, 24148 Germany
AU: Diaz, J
EM: jdiaz@ucv.cl
AF: Universidad Catolica de Valparaiso, Av. Altamirano 1480, Valparaiso, NNN Chile
AU: Reichert, C
EM: christian.reichert@bgr.de
AF: BGR, Stilleweg 2, Hannover, 30655 Germany
AU: Vera, E E
EM: era@dgf.uchile.cl
AF: Universidad de Chile, Blanco Encalada, Santiago, NNN Chile
AB: Multibeam bathymetry along central Chile provides a detailed map of recent tectonic deformation of the margin and incoming oceanic plate from about 28? S to 36? S. The data were collected during R/V SONNE cruises 101, 102, 104 and 161 and a cruise with R/V Vidal Gormaz. Individual pings were edited and cleaned and the different surveys have been merged after depth calculations using a different measured velocity function for each of them. The oceanic Nazca plate is covered by about 100 m of pelagic sediment and the morphology of the igneous basement is displayed well in the bathymetric maps. The oceanic plate topography changes markedly along the subduction zone and exerts a first order control in the distribution of trench sediment infill and in the tectonic style of deformation of the margin. A major boundary occurs at latitude 32?-33? S where the hotspot volcanic chain of Juan Fernadez is currently subducting. The chain subducts oblique to the margin strike and thus the tectonic boundary has been migrating along the subduction zone through time. South of the area of ridge subduction the trench is filled with turbidites and a 20-40 km wide accretionary prism occurs at the front of the continental slope. The upper slope has a smooth morphology indicative of a quiet tectonic domain. At the current area of ridge subduction and north of it (28?-33?S) the trench has a reduced turbiditic infill. The trench infill seems to be at minimum at 31-32S and slightly larger to the north as the trench axis becomes deeper. Here, a small ridge at the slope toe may indicate that reduced accretion is active. The continental slope is deeper and more rugged that to the south displaying a series of small midslope basins. Here, the continental slope morphotectonic structure is the product of tectonic erosion due to the passage of the volcanic ridge.
DE: 3045 Seafloor morphology and bottom photography
DE: 8100 TECTONOPHYSICS
DE: 8105 Continental margins and sedimentary basins
DE: 8150 Plate boundary--general (3040)
SC: Tectonophysics [T]
MN: 2003 Fall Meeting