The eastern foothills of the Eastern Cordillera of Colombia: An example of multiple factors controlling structural styles and active tectonics

Abstract

We decipher the geometry, timing, and kinematics of deformation of a region in the eastern foothills of the Eastern Cor dillera of Colombia. We assess the infl uence of inherited structural fabrics, changes in basin geometry, erosional denudation, and the characteristics of the tectonic stress fi eld with respect to the evolution of the structural styles of the deformation front in the Eastern Cordillera. Detailed structural and geomorphic mapping of an area of ~5000 km 2 , analysis of seismic-refl ection profi les, crosssection balancing, tectonic stress-fi eld indicators, and new apatite fi ssion-track data are used to characterize the partitioning of Late Cenozoic deformation in the eastern foothills of the Eastern Cordillera of Colombia. During the late Miocene-Pliocene, in the Eastern Cordillera, deformation migrated from inverted master normal faults to lowelevation, low-amplitude structures in the foreland. However, this shift in the locus of deformation was not spatially uniform. The deformation front is wider in a northern sector of the Cordilleran foothills, where sedimentary units are thicker, and shortening is perpendicular to the structures. This shortening direction is identical to the direction of the greatest horizontal stress S Hmax as seen in borehole breakouts. During the late MiocenePliocene, basement ranges are passively uplifted by younger, more frontal thrusts. The eastern foothills of the Eastern Cordillera thus reveal a complex combination of factors responsible for the structural styles and partitioning of active deformation in an inversion orogen. Over time, the most important factor changes, from the role of inherited structural fabrics to the geometries of basin fi lls.

Active mountain building along the eastern Colombian Subandes: A folding history from deformed terraces across the Tame anticline, Llanos Basin

“…Additional evidence of neotectonic activity is observed by older strata thrust over Quaternary sediments of the alluvial plain ( Fig. 1C; Mora et al, 2010;Tapias et al, 2007). Fluvial and alluvial sedimentary deposits composed of coarse-grained, poorly sorted conglomerates are sourced from the hinterland.…”

“…1C; Mora et al, 2006Mora et al, , 2008Mora et al, , 2010Tapias et al, 2007). In the south, the right-lateral Guayaquil-Algeciras fault system transfers part of its slip to the Monserrate thrust Veloza et al, 2012), which juxtaposes Paleozoic sediments over the modern alluvial plain.…”

Hyperspectral imaging for the determination of bitumen content in Athabasca oil sands core samples

“…Deformation is dominated by the subducting Caribbean or Nazca plates north and south of 4°N, respectively (Cortés et al, 2005;Mora et al, 2010b). Eastern Colombia is dominated by two main mountain chains, the Central and Eastern Cordilleras, which are separated by the Magdalena intermontane valley (Figure 1).…”

Formation of passive-roof duplexes in the Colombian Subandes and Perú

“…8; cross sections in Fig. 11; for cross sections in the same area, see also Martínez, 2006;Mora et al, 2010b;Egbue and Kellogg, 2012;Jimenez et al, 2013). On the other hand, it is not associated with the foreland-dipping limb on the hinterland side of the frontal syncline in cases where the syncline was at almost the same regional level as the undeformed foreland (Fig.…”

“…More recent publications (Hermoza et al, 2005;Gil et al, 2001;Kley et al, 1999;Ramos et al, 2002;Kozlowski et al, 2005;Echavarria et al, 2003;Espurt et al, 2008Espurt et al, , 2011Mora et al, 2006Mora et al, , 2010aMora et al, , 2010bMora et al, , 2010c have shown almost no new documented passive-roof duplex structures in the outer parts of the Subandean belts, with the notable exception of those mostly located north of the Bolivian orocline. Oil companies have studied these cases mostly because of the exploratory efforts (Dunn et al, 1995).…”