Uplift of the Altiplano-Puna plateau: A view from the west

Abstract

[1] The western flank of the Central Andean Plateau is a crustal-scale monoclinal fold, expressed in the geomorphology and in the westward tilt of fore-arc basin strata. Data from three fore-arc basins quantify the magnitude and time of displacement of the plateau system relative to the fore arc. From 18°30′S to 22°S there is a single monocline strand. There, other authors documented ∼2000 m (±500 m) of early and middle Miocene structural relief growth across small-scale monoclines, and our data reveal 810 m (±640 m) of ∼11–5 Ma relief growth and 400 m (±170 m) relief growth since ∼5 Ma across a long-wavelength monoclinal fold limb. This structural relief growth since ∼11 Ma approximates the topographic relief growth between the fore arc and the Altiplano plateau. From 22°S to 24°S there are two subparallel long-wavelength monoclines. Structural relief on the east side of the fore arc increased by 2840 m (±2510 m) during ∼17–10 Ma and by 2320 m (±1050 m) since ∼10 Ma. Some part of this monoclinal limb rotation led to topographic uplift of the adjacent Puna plateau. Rotation across the western monocline could have increased the altitude of the fore-arc basins by <900 m since ∼6 Ma and may result from intense heating of the eastern margin of the cold and strong Atacama lithosphere block. Although the wavelengths of the monoclines vary along strike and through time, the monoclinal style of deformation dominated the uplift history of the eastern fore arc of the central Andes throughout the Neogene.