GEOMORPHIC EVIDENCE FOR POST-10 MA UPLIFT OF THE WESTERN FLANK OF THE CENTRAL ANDES 18°30'-22°S

The western Andean mountain front forms the western edge of the Altiplano Plateau. Between 18.50 and 22 degrees latitude, the mountain front has ~3000 m of relief over ~ 50 km horizontal distance that has developed in the absence of major Neogene deformation. Models of the evolution of the plateau, as well as paleoatlimetry estimates all call for continued uplift of the Plateau into the late Miocene. Examination of longitudinal river profiles from 20 basins draining the western Andean mountain front reveal several streams that contain knick point bounded segments that are used to reconstruct the history of post 10 Ma relief creation in this part of the Andes. We can account for the existence of 1 km of uplift occurring between 10 and ~6.3 Ma.