Renewed uplift of the Central Andes Forearc revealed by coastal evolution during the Quaternary

Abstract

Accepted Manuscript for publication in Earth and Planetary Science LettersMost of the Pacific coast of the Central Andes, between 15°S and 30°S, displays a wide (a couple of kilometres) planar feature, gently dipping oceanwards and backed by a cliff. This morphology, usually of marine orgin, is called rasa, and argues for a recent and spatially continuous uplift of the margin over the 1,500-km-long coastal region we describe. The cliff foot is found at a similar elevation (~110 m amsl) all over the studied area, with the exception of peninsulas such as the Mejillones Peninsula. The compilation of published chronological data and the extrapolation of re-appraised uplift rates provide evidence for a common cliff foot age of around 400 ka (i.e., Marine Isotopic Stage MIS 11). This, together with other geological constraints, indicates a Quaternary renewal of uplift in the Central Andes forearc after a late Pliocene quiescence or subsidence