HR: 1340h
AN: T13C-1471    [Abstracts]
TI: Southern Costa Rica: an Island-arc Segment That Behaves Like a Doubly Vergent Orogen
AU: Brandes, C
EM: brandes@geowi.uni-hannover.de
AF: Institut für Geologie, Leibniz Universität Hannover, Callinstr. 30, Hannover, 30167, Germany
AU: * Winsemann, J
EM: winsemann@geowi.uni-hannover.de
AF: Institut für Geologie, Leibniz Universität Hannover, Callinstr. 30, Hannover, 30167, Germany
AB: Southern Central America is a Mesosoic/Cenozoic island-arc that evolved from the subduction of the Farallón Plate below the Caribbean Plate. The southern Costa Rican land-bridge comprises deformed fore-arc and back-arc basins in the west and east, respectively, separated by the up to 3.8 km high Talamanca Range. The structure of the southern Central American island-arc is similar to doubly vergent and asymmetric orogens. The deformed fore-arc basin in the west and the Limon fold-and-thrust belt in the east can be interpreted as pro-wedge and retro-wedge, respectively. The Talamanca Range represents the uplifted block in between. The pro-wedge is wider and has a lower slope angle than the retro-wedge. The uplift of the Talamanca Range is probably related to a system of conjugate shear zones. Precipitation is unevenly distributed, with orographic effects concentrating precipitation in SW Costa Rica, which has caused pro-wedge denudation, leading to exhumation of granitic rocks at in the interior of the mountain range. The large-scale structure of the Central American island-arc in southern Costa Rica can be described using models of continental collision zones. Previous studies attributed the deformation and uplift pattern to the subduction/collision of the Cocos Ridge. Another reasonable driving mechanism for the evolution of such an orogen in an oceanic island-arc setting is the basal traction due to long-term subduction of the Cocos Plate at a very low angle.
DE: 8185 Volcanic arcs
SC: Tectonophysics [T]
MN: 2007 Fall Meeting