--> Abstract: Tectonic Evolution of the Limon Fold and Thrust Belt, Limon Back-Arc Basin, Costa Rica, by Christian Brandes, Allan Astorgao, Peter Blisniuko, Ralf Littkeo, and Jutta Winsemann; #90039 (2005)

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Tectonic Evolution of the Limón Fold and Thrust Belt, Limón Back-Arc Basin, Costa Rica

Christian Brandes1, Allan Astorga2, Peter Blisniuk3, Ralf Littke4, and Jutta Winsemann1
1 Universität Hannover, Hannover, Germany
2 Escuela Centroamericana de Geología, San José, Costa Rica
3 Universität Potsdam, Potsdam, Germany
4 Technical University of Aachen (RWTH), D-52056 Aachen, Germany

The Limón Back-arc Basin belongs to the southern Central American arc-trench system and is situated beneath the present-day coastal plain and continental shelf of eastern Costa Rica. The basin is subdivided into a northern and into a southern sub-basin, separated by the E-W striking Trans Isthmic Fault System. The northern basin is nearly undeformed whereas the southern basin has been overprinted by the development of a large fold-and-thrust belt. A dense grid of 2D seismic lines orientated parallel and perpendicular to the basin axis allows a detailed reconstruction of the deformation in both regions. The South Limón fold-and-thrust belt is dominated by concentric or asymmetric hangingwall anticlines and southwestward dipping listric thrusts, which indicate a northeast-southwest directed compression. All thrusts sole into one horizontal detachment. Below the detachment no significant deformation can be observed. The position of this detachment is controlled by a lithological change from shales to limestones. A subsidence curve derived from 1D basin modelling implies an onset of deformation in Mid-Miocene times. The geometry of the fold-belt indicates a northeastward propagation of folding and thrusting. In addition, small and asymmetric piggy-back basins are associated with the fold-belt. These basins show highest sediment thickness in their central parts and a decrease in thickness towards the hangingwall anticlines. Together with onlap patterns, this gives evidence for contemporaneous sedimentation and deformation. Tectonic forward modelling was executed to reconstruct the interplay of fault-propagation, anticline growth and filling of the piggy-back basins.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005