Tracking evolution of Andean ranges bounding the Middle Magdalena Valley basin, Colombia

The shortening history of the northern Andes is important to our understanding of convergent continental deformation. However, the timing of significant shortening-related uplift in the northern Andes is poorly constrained, with estimates ranging from early-Cretaceous to Miocene. Detrital zircon U-Pb ages from the middle Magdelena Valley basin in Colombia reveal two pronounced provenance shifts during the Cenozoic. The first shift occurs between lower and upper Paleocene strata, where age spectra switch from Proterozoic-dominated to Phanerozoic-dominated. We attribute this change to uplift-related exhumation of the Central Cordillera. The second shift occurs between middle-upper Eocene and upper Oligocene strata, where increased Grenville and diminished mid- Jurassic-Cenozoic zircon ages are consistent with initial shortening-related uplift of the Eastern Cordillera. The U-Pb results improve our understanding of the Cenozoic uplift/exhumation history of the Colombian Andes and provide a basis for future studies that consider the possible role of Andean uplift on Cenozoic climate.