HR: 0800h
AN: T31A-0284    [Abstracts]
TI: Recently active reverse faulting in the Atacama Basin area, northern Chile: Implications for the distribution of convergence across the western South America plate boundary
AU: * Shyu, J H
EM: jbhs@iaag.geo.uni-muenchen.de
AF: Department of Geo- and Environmental Sciences, Ludwig-Maximilians University Munich, Luisenstrasse 37, Munich, 80333, Germany
AU: * Shyu, J H
EM: jbhs@iaag.geo.uni-muenchen.de
AF: Tectonics Observatory, Division of Geological and Planetary Sciences, Caltech, Pasadena, CA 91125, United States
AU: Gonzalez, G
EM: ggonzale@ucn.cl
AF: Departamento de Ciencias Geologicas, Universidad Catolica del Norte, Antofagasta, 1240000, Chile
AU: Simons, M
EM: simons@gps.caltech.edu
AF: Tectonics Observatory, Division of Geological and Planetary Sciences, Caltech, Pasadena, CA 91125, United States
AU: Aron, F
AF: Departamento de Ciencias Geologicas, Universidad Catolica del Norte, Antofagasta, 1240000, Chile
AU: Veloso, A
AF: Departamento de Ciencias Geologicas, Universidad Catolica del Norte, Antofagasta, 1240000, Chile
AB: The western South American margin is one of the most active continental plate boundaries in the world. The ongoing convergence between the Nazca plate, or formerly the Farallon plate, and the South American plate produced the wide deformation belt of the Andes. In order to obtain more information about the active deformations in the central Andean belt to better understand the current distribution of convergence across the orogen, we attempted to map major structures that appear to be active recently by their topographic expressions using SRTM DEM and Landsat satellite images, followed by field observations. Results of our mapping show that there are many reverse faults that may be recently active in the area surrounding the Atacama Basin, in the Preandean Depression in northern Chile. These include a series of active reverse faults and related folds at the southeastern corner of the Atacama Basin, a major fold system that may be produced by an underlying fault just east of the basin, and a series of folds that forms the Cordillera de la Sal in the northern and western part of the basin. At the southeastern corner of the Atacama Basin, several geomorphic features indicate that at least some of the structures there have been active quite recently, including small drainages that cut through the folds and form active alluvial fans. Similar features of active river incision across folds are also present in the northern part of the basin. The fold system east of the basin may be one of the most important structures in the area. Deformed lava flows and deflected drainages indicate that this structure has been active recently, and growth strata near the fold suggest that it has been active for several myr. If so, the structure may be a major reverse fault system that defines the eastern boundary of the Atacama Basin, and may thus be an important onland structure that is responsible for absorbing part of the plate convergence.
DE: 8015 Local crustal structure
DE: 8104 Continental margins: convergent
DE: 8107 Continental neotectonics (8002)
DE: 8175 Tectonics and landscape evolution
SC: Tectonophysics [T]
MN: 2007 Fall Meeting