HR: 08:15h
AN: T11D-02 INVITED    [Abstracts]
TI: Subduction Along the South Caribbean Deformed Belt: Age of Initiation and Backthrust Origin
AU: * Mann, P
EM: paulm@ig.utexas.edu
AF: Jackson School of Geosciences, Univ of Texas at Austin, 10100 Burnet Road (Bldg 196), Austin, TX 78758, United States
AU: Kroehler, M
EM: margaretk@ig.utexas.edu
AF: Jackson School of Geosciences, Univ of Texas at Austin, 10100 Burnet Road (Bldg 196), Austin, TX 78758, United States
AU: Escalona, A
EM: alejandro.escalona@uis.no
AF: Dept of Petroleum Engineering, Univ of Stavanger, Risaberguegen 846, Stavanger, 4036, Norway
AU: Magnani, B
EM: mmagnani@memphis.edu
AF: CERI, The University of Memphis, 3890 Central Ave, Memphis, TN 38152, United States
AU: Christeson, G
EM: gail@ig.utexas.edu
AF: Jackson School of Geosciences, Univ of Texas at Austin, 10100 Burnet Road (Bldg 196), Austin, TX 78758, United States
AB: The South Caribbean deformed belt (SCDB) represents a submarine prism formed at the interface between subducting oceanic material in the Colombian and Venezuelan basins and arc terranes along the northern edge of the South American continent. The SCDB and subducted Caribbean slab extends 1500 km from Panama to the Aves Ridge and is similar in scale to better studied magmatic subduction zones in the Lesser Antilles and Central America. The age of subduction of the Venezuelan basin at the SCDB has been examined by dating asymmetrical sediment wedges inferred to have formed above the bending and subducting slab of the Venezuelan basin. Ages are constrained by ties to DSDP wells drilled in the Venezuelan basin ~150 km north of the SCDB. Onlapping wedges are oldest in the western area near the Beata Ridge (middle Eocene), of intermediate age in the central area (early Miocene), and youngest in the east near the Aves Ridge (Mio- Pleistocene). Overlying younger wedges in all areas demonstrate that subduction continued following its initiation. Similar ages of deformed syn-thurst wedges are known from the now inactive continental foreland of northern South America in a belt from western Venezuela to Trinidad. Based on this correlation, we propose a simple back arc thrusting origin for the SCDB that is analogous to the eastern Sunda arc of Indonesia. The obliquity of convergence in the Caribbean case has produced a longlived, eastwardly-migrating backthrust that contrasts to more static backthrust in Sunda. The immediate onset of backthrusting following continental collision means that South America-Caribbean convergence was accommodated by newly organized and focussed subduction at the SCDB backthrust; the "collided" crust of intervening accreted arc terranes remains remarkably unaffected by regional shortening effects.
DE: 1031 Subduction zone processes (3060, 3613, 8170, 8413)
DE: 8123 Dynamics: seismotectonics
DE: 8157 Plate motions: past (3040)
DE: 8158 Plate motions: present and recent (3040)
DE: 8169 Sedimentary basin processes
SC: Tectonophysics [T]
MN: 2007 Fall Meeting