Abstract

CETINA, Lina María; CUELLAR-CARDENAS, Mario Andrés; OSORIO-NARANJO, Jairo Alonso  and  QUIROZ-PRADA, Carlos Augusto. Evolution of the Cretaceous-Paleocene deformation on the western edge of Colombia (northern sector). Bol. geol. [online]. 2022, vol.44, n.2, pp.15-50.  Epub July 18, 2022. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v44n2-2022001.

In the occidente colombiano we identified an extensional deformation during the Cretaceous, and a transpressive deformation during the Upper Cretaceous-Paleocene; the latter considered to belong to the Calima orogenic event. Evidence for the extensional deformation includes the presence of graben and horst structures at the scale of regional maps, the existence of sub-horizontal mylonitic zones, and dome-like structures that are indicative of core complexes. Based on the compilation of geochronological and paleontological data and an analysis of regional structures, we concluded that the first deformative event occurred in the Cretaceous, with a maximum extensional stress displaying an azimuth of 103°N. A second deformative event started in the western flank of the Cordillera Central at ca. 70 Ma, and propagated to the north - northwest. This event is associated with a dextral-transpressive deformation and reworked the inherited extensional fabric, generating a progressive inversion of the existing graben structures under a prevailing contraction oriented at 194°N. From these conclusions, based on the lithological-structural characteristics of the units, we propose an in-situ origin for the Cretaceous margin of the NW of South America (northern sector of the occidente colombiano) and its subsequent consolidation during Cretaceous-Paleogene. Multiple events shaped this margin, including uplift, topography construction, collapse, erosion, depocenter movements, and closure of basins from the continental edge to northwestern Colombia.

Keywords : Occidente colombiano; Extensional and transpressive deformation; Core complex.

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