Tectonic and Climatic Signatures of Cenozoic Mountain Building in the Colombian Andes

Saylor, Joel E.¹; Mora, Andres; Anderson, Veronica J.; Caballero, Victor M.; Horton, Brian K.; Shanahan, Timothy M.; Parra, Mauricio; Nie, Junsheng; Quintero, Isaid; and Ramirez Arias, Juan Carlos
¹[email protected]

A multi-year academic-industry collaboration has advanced understanding of the long-term tectonic and climatic evolution of the Eastern Cordillera of Colombia and adjacent basins using diverse stratigraphic, structural, geochronologic, and geochemical techniques. The combined US-Colombia research group has published results in over 12 peer-reviewed articles that address the linked deformation and basin histories of the Middle Magdalena Valley (MMV), Floresta (axial Eastern Cordillera), and Llanos foreland basins.

Regional detrital provenance signatures from Upper Cretaceous–lower Paleocene strata point to an eastern (cratonic) source. By the mid-Paleocene, sediment was sourced from the western magmatic arc (Central Cordillera) to the retro-arc foreland basin system encompassing the MMV and Floresta regions. Eastward propagation of the retro-arc thrust belt exhumed MMV basement producing a mid-Eocene unconformity. Diverse detrital signatures from synchronous strata in the Floresta basin suggest rapid exhumation of a metamorphic basement source. However, coeval sediments in the Eastern Foothills were derived from the eastern craton, suggesting an underfilled Paleogene foreland basin with an emergent forebulge separating the Floresta region from the Eastern Foothills. Eastward advance of shortening into the Eastern Cordillera is recorded by late Eocene–early Oligocene recycling of foreland sediments (originally deposited in the Eastern Cordilleran zone) toward both the west (into the MMV) and east (into the Floresta and Eastern Foothills basins). The post-Oligocene sedimentary and structural record in the MMV and Eastern Foothills basin record generalized inversion acriss the Eastern Cordillera during the late Oligocene-early Miocene and fragmentation of a previously contiguous foreland basin.

This protracted early history of crustal shortening was followed by late Miocene-Pliocene topographic growth of the Eastern Cordillera. Preliminary branched GDGT paleo-temperature estimates for the ~2600-m-high Bogota plateau (in the Eastern Cordillera) suggest a major shift between 6 and 4 Ma that may record a rapid increase in surface elevation of >1 km. Such a punctuated history of uplift contradicts the long-term history of Cenozoic shortening and crustal thickening, underscoring the need to better explore the potential dynamic links among deformation, erosion, climate, and surface uplift.

AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013