Thermochronological constraints for reconstructing the tectonic history of the northern Central Cordillera (Serranía de San Lucas), Colombia

The Northern Andes are characterized by episodes of exhumation at around 80, 60–50, 40, 25 and 15–0 Ma in the Central and Eastern Cordilleras, Santander Massif, Sierra Nevada de Santa Marta and Merída Andes. Here we present a preliminary set of low-temperature thermochronological data from the Serranía de San Lucas in the northern Central Cordillera, which demonstrate that the timing of exhumation of this region is different from that of the surrounding massifs such as the Antioquia batholith, the Santander Massif or the Sierra Nevada de Santa Marta. The thermochronological data show that the volcanic rocks of the Early Jurassic Noreán Formation exposed in the Serranía de San Lucas to the west of the Middle Magdalena River basin and the northern Santander Massif were buried beneath 6–7 km of Upper Jurassic to Upper Cretaceous/Paleocene sedimentary rocks, then slow erosional exhumation resumed at about 80–60 Ma as reflected by slow cooling rates of 2–4°C/myr. No evidence is found for exhumation at 25 Ma as it has been previously detected in the Antioquia batholith or the Santander Massif. The Serranía de San Lucas tectonic evolution is seen in connection with Mid-Late Jurassic to Early Cretaceous extension and Late Cretaceous compression and accretion of oceanic blocks to the western margin of the South American plate, and flat slab subduction of the Caribbean plate during the Eocene–Oligocene.