Paleocene–Miocene topographic and tectonic evolution of the northern central Andean plateau, southern Peru

Abstract

The Paleocene–Miocene sedimentary successions along the Western Cordillera – Altiplano Plateau margin in southern Peru record the growth history of the northern Altiplano Plateau and the development of the foreland basin system. We evaluate the paleoelevation history of the northern Altiplano Plateau for the period of primary upper crustal shortening (i.e., Paleocene–Miocene) to determine the amount of shortening-related surface uplift. We provide new apatite fission-track and tuff zircon U–Pb ages to add to the existing age models of the strata. We further calculate the first-order approximation of paleoelevations of these formations from paleo-meteoric water δ18Omw values reconstructed from authigenic carbonate δ18Oc. The calculations show that surface elevations increased by more than 1 km along with the basin development from backbulge and foredeep to wedge-top and hinterland basins. The calculated paleoelevation of 1.8–2.4 km at the end of contractional deformation during the late Miocene indicates that a rapid surface uplift of more than 1.5 km is required to attain the modern high elevations. It is further inferred that this post-late Miocene surface uplift was probably associated with the lower crustal flow and ensuing convective removal of lower lithosphere materials.