Influencia de la carbonatación edáfica en la datación por luminiscencia de depósitos aluviales semiáridos en el SE de la Península Ibérica

Abstract

The recent developments in luminescence dating have made it possible to establish robust chronologies on semiarid alluvial deposits in the SE of the Iberian Peninsula reaching up to 300 ka. Despite the significant improvements in the technique, the reliability of the estimated ages can be compromised by the abundance of carbonate (Nathan y Mauz, 2008) which might lead to the misestimation of the representative dose rate (ionizing radiation received per time unit) for the burial period. Since the sampled deposits show carbonate enrichment with calcrete development with carbonate enrichment, the effect of this on the estimated ages has been analysed. The 10 samples measured show a clear correlation between the calculated dose rate and the concentration of carbonates. A correction of the estimated ages has been applied according to this correlation, deriving in a reduction of up to 40% for the samples with the highest concentrations (CaCO3>70%). The corrected ages are coherent with the stratigraphy and provide a consistent chronology of the tectonic activity of the studied region. This study points out the effect of carbonates on the estimated ages and shows the major impact that could have on active tectonics studies in the Eastern Betics, where slip rates are often based on OSL ages obtained from semiarid alluvial fan deposits with high carbonate content.