Abstract

MONTERO-POHLY, Walter et al. Neotectonic and structural implications based on paleoseismology of the southern sector of the Cartago Transpression Zone, Costa Rica. Rev. Geol. Amér. Central [online]. 2020, n.63, pp.115-146. ISSN 0256-7024.  http://dx.doi.org/10.15517/rgac.v0i63.44028.

In this work we present the principal results of a paleoseismological study performed in trenches dug across the Cocorí fault, located at the southern part of the Cartago Transpression Zone. Based on radiocarbon dating we define tectonic deformations occurred before the last 28000 years and after 10000 years (last part of the Upper Pleistocene and Holocene). The tectonic deformations observed in the trenches are thrust faults with a strike-slip component, probably sinistral. We also defined plastic deformation, where the anticlines show south vergence. Two of the faults had metric displacements and various folds had nearly metric amplitudes. However, the low angle of the faults and the ductile behavior of the materials involved in the deformation, do not allowed us to find evidence of coseismic surface ruptures. This limitation implied that we do not being able to temporally bracket the occurrence of any paleoearthquake. A schematic neotectonic model of two fault-bend folds, trending nearly east-west, allows us to explain the geomorphological characteristics of the southern sector of the Cartago Transpression Zone and the structural observations found in the different trenches.

Keywords : Tectonic geomorphology; Central Costa Rica Deformed Belt; Aguacaliente fault System; Cocorí Fault; Fault-bend fold.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )