The exhumation of the Northern Patagonian Massif Gondwana Planation surface due to uprising during the Oligocene

Abstract

The altiplano (or high plain) of the Northern Patagonian Massif is a large, 100.000 km2 geomorphological unit that rose from sea level to at least 1200 metres above sea level in Early Oligocene times, as a consequence of epeirogenic uplift. This uniform tableland feature is essentially a Cretaceous planation surface carved on Paleozoic igneous and metamorphic rocks of the Northern Patagonian Massif. This planation surface had been preserved by a thin and scattered cover of Maastrichtian-Danian marine sediments and late Oligocene-early Miocene basaltic flows. Erosion since Middle Miocene times at this tableland has exposed much of the Gondwana planation surface and developed numerous basaltic plateaus by relief inversion.