Paleomagnetic analysis of river terraces of the Arlanza, Arlanzón, and Duero rivers (N Spain) and chronological context

Abstract

The Duero basin, like most of the Cenozoic basins of the Iberian Peninsula, is filled with Pleistocene continental sediments of detrital origin, reflecting progressive river inicision in the form of staircases terraces present in the basin. In the Northeast of the Basin, these morphological features are particularly important, given their relationship with the development of the karst complex where the archaeological sites of Atapuerca are found. The precise chronology of the fluvial terraces is still under debate, although; analysis by electromagnetic spin resonance (ESR), have provided ages of about a million years for the upper terraces (Moreno et al., 2012). This paper presents an approach to the chronology of the upper Duero river terraces using paleomagnetic analysis on samples from the Arlanza, Arlanzón and Duero rivers. Samples have been taken from a total of five different locaties, which correspond at the total number of terraces studied, spread across these three rivers: Tordómar and Santa Inés in the Arlanza,; Zalduendo and Villacienzo in the Arlanzón; and Alconaba in the Duero. Our initial results reveal a dominance of positive (normal) polarity directions which can be attributed to the Upper Pleistocene. Details on the rock magnetic properties as well as the Anisotropy of Magnetic Susceptibility will also be discussed.