New stratigraphie data on the initiation of mountain building at the eastern front of the Colombian Eastern CordHlera

The Upper Cretaceous to Cenozoic evolution of the central and eastern Colombian Andes is linked to thedevelopment and migration of a foreland basin system (Magdalena Valley Basin) coupled to the CentralCordillera (CC) that became isolated from the present Llanos Foreland Basin after the uplift of the EasternCordillera (EC) (Figure lA).Numerous works (Schamel,