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Sedimentitas marinas del Neógeno en la bahía de Tumaco, Nariño

 Volume 3 Chapter 3

Chapter 3

Construction of the Eastern Cordillera of Colombia: Insights from the Sedimentary Record

Brian K. HORTON, Mauricio PARRA and Andrés MORA

https://doi.org/10.32685/pub.esp.37.2019.03


Citation is suggested as: 

Horton, B.K., Parra, M. & Mora, A. 2019. Construction of the Eastern Cordillera of Colombia: Insights from the sedimentary record. In: Gómez, J. & Mateus–Zabala, D. (editors), The Geology of Colombia, Volume 3 Paleogene – Neogene. Servicio Geológico Colombiano, Publicaciones Geológicas Especiales 37, p. 85–127. Bogotá. https://doi.org/10.32685/pub.esp.37.2019.03


Abstract 


A continuous, long–lived sedimentary record contains important evidence bearing on the geologic evolution of the Eastern Cordillera in the northern Andes of Colombia. Today, this largely isolated NNE–trending mountain range forms a ~1–3 km–high topographic barrier separating the Magdalena Valley hinterland basin from the Llanos Foreland Basin. A Mesozoic – Cenozoic history of marine and non–marine sedimentation affected the Eastern Cordillera and flanking Magdalena and Llanos provinces during contrasting tectonic regimes. (i) Jurassic to earliest Cretaceous extension led to the development and linkage of extensional sub–basins (commonly half graben features governed by normal faults) in selected regions. (ii) A subsequent phase of postextensional thermal subsidence generated a thermal sag basin across a broader region. (iii) In latest Cretaceous to Paleocene time, initial crustal shortening in the Central Cordillera created a regional flexural basin that was successively broken by the Paleocene – Oligocene emergence of thrust/reverse–fault related uplifts within the Eastern Cordillera and the partitioning of the original regional basin into the Magdalena hinterland basin and Llanos Foreland Basin. (iv) Major Neogene uplift and establishment of an effective topographic barrier occurred as continued shortening became focused along the bivergent eastern and western flanks of the fold–thrust belt comprising the Eastern Cordillera. Shortening commonly involved contractional reactivation of preexisting normal faults and inversion of pre–foreland basin elements. This geologic history is largely expressed in the clastic sedimentary archives of the Eastern Cordillera, Magdalena Valley Basin, and Llanos Basin. Growth strata and cross–cutting relationships among fold–thrust structures and basin fill provide essential timing constraints for individual structures, particularly when integrated with thermochronological data. Regional stratigraphic correlations and sediment accumulation histories help to identify shared and divergent stratigraphic histories during progressive basin compartmentalization. Substantial shifts in sediment provenance, identified through U–Pb geochronology, demonstrate the changes in sediment source regions and paleodrainage patterns during several changes in tectonic conditions.

Keywords:   Eastern Cordillera, foldthrust belt, foreland basin, provenance, UPb geochronology.