ESR Chronology of the Fluvial Sequence of Cueva Del Silo (sierra De Atapuerca, Spain)

The Cueva del Silo is part of the lower karst level of the Cueva Mayor-Cueva del Silo karst system (Sierra de Atapuerca, Burgos, Spain), whose evolution has preserved an impressive archeo-paleoanthropological sequence since the Early Pleistocene. Cueva del Silo is remarkable for the presence of fluvial deposits that record the entry of the Arlanz ' on River water in the cave system, providing a key sequence to investigate the fluvio-karstic relationships that give rise to this endokarst system. In order to provide a chronological framework to these fluvial deposits, six sediment samples were dated by Electron Spin Resonance and 16 samples by paleomagnetism, collected from two outcrops: Galeria de las Arenas and Sala del Caos. Our results provide maximum mean age of around 1600 ka and a minimum age of 916 +/- 136 ka for the deposits in Sala del Caos. The younger date from Sala del Caos might represent the last fluvial input from Arlanz ' on River in the lower karst level. In contrast, ESR ages estimates of 1268 +/- 133 ka and 1262 +/- 108 ka were obtained for Galeria de las Arenas sequence, which could indicate re-sedimentation processes from the intermediate karst level where similar ages were published. The annual dose might be wrongly assessed due to the re-sedimentation processes inside the karst, hence, ESR ages for these facies should be treated with extreme caution.