Dating the Earliest Pleistocene alluvial terrace of the Alcanadre River (Ebro basin, NE Spain): insights into the landscape evolution and involved processes

Abstract

This work presents the results of a multi-approach study of the extensive highest terrace (Qt1) of the Alcanadre River system (Ebro Basin, Spain). The timing of the earliest morphosedimentary fluvial archives in the Ebro Basin (NE Spain) under exorheic conditions is provided from ESR dating techniques applied to optically bleached quartz grains and complemented by palaeomagnetic data and morphopedosedimentary features. A mean ESR age estimate of 1276 ± 104 ka based on the Ti-centre provides the oldest numerical age obtained for a Quaternary terrace in the Iberian Peninsula. The polarity determined by palaeomagnetic analysis is normal, although it must be contained within the Matuyama reversed period. Therefore, Cobb Mt is the more suitable chron, although Jaramillo cannot be fully ruled out. This age is consistent with the last stretch of the Matuyama reversed Chron deduced from palaeomagnetism. Relevant consequences concerning the palaeogeographical setting, palaeoclimatic context and fluvial incision rates are discussed to elucidate the landscape evolution of NE Iberia.