Original paper

Geophysical prospection on Late Quaternary sediments in the Gállego Valley, Central Spanish Pyrenees

Hirsch, Florian; Raab, Thomas

Abstract

This study aims to characterize the Late Quaternary stratigraphy in a type region of Pleistocene glaciation in the Central Spanish Pyrenees by using geophysical prospection techniques to extrapolate stratigraphical field information from soil pits. The main objectives are (i) to identify the thickness of the Quaternary sediments, (ii) to characterize the internal structures and stratifications within the Quaternary deposits and (iii) to test the validity of combined geophysical prospection techniques, including shallow seismic refraction (SSR) and electric resistivity tomography (ERT). We focus on two selected study sites: the Late Pleistocene terminal moraine at Senegüé on the bottom of the Gállego Valley and a Pleistocene non-glaciated slope located nearby. This study proves that information about the depth, structure and distribution of Late Quaternary sediments (glacial, periglacial and fluvial) can be gathered by the combination of geophysical techniques (SSR and ERT). These techniques allow for a reliable, inexpensive and fast extrapolation of stratification information from soil pits and enable Late Quaternary and Eocene sediments to be distinguished. The reconstruction of the sediment genesis is facilitated by the geophysical techniques due to the potential to prospect the internal structures of large areas.

Keywords

electrical resistivity tomographylate quaternary sedimentsshallow seismic refraction