Evolución geomorfológica cuaternaria del Alto Ebro: sector cuenca de Miranda (España)

Abstract

Sedimentological, morphostratigraphical and chronological analysis of sediments has determined the geomorphological evolution of the Miranda Basin. These analyses have identified 5 terrace levels related to the Ebro river: a fluvial level linked to the Arroyo San Miguel, 2 pediment levels and various slope deposits. Terrace levels T4 and T5 have been dated using Optically Stimulated Luminescence at 13 and 10 ka. Terrace levels T1, T2 and T3 were formed at 191 ka, 109 ka and 70 ka. Remnants of the Arroyo San Miguel were created during the Early Pleistocene. Pediment G1 dates back to 70 ka and G2 to 13 ka. Slope deposits originated during the Last Glacial Maximum. Presented evidence shows a geomorphological system mainly active during glacial stages. The Ebro river experienced fluvial sedimentation phases during interglacial stages too, but with very different characteristics. Fluvial incision coincides with climatic transitions and pediment incision with interglacials.