Glacial and fluvial deposits in the aragón valley, central‐western pyrenees: chronology of the pyrenean late pleistocene glaciers

Abstract

The ragón alley glacier (entral estern yrenees) has been studied since the late nineteenth century and has become one of the best areas in the yrenees to study the occurrence of leistocene glaciations and the relationships between moraines and fluvial terraces. New morphological studies and absolute ages for moraines and fluvial terraces in the ragón alley allow a correlation with other yrenean glaciers and provide solid chronologies about the asynchroneity between global last glacial maximum and the maximum ice extent. Six frontal arcs and three lateral morainic ridges were identified in the illanúa basin terminal glacial complex. The main moraines (1 and 2) correspond to two glacial stages (oxygen isotopic stages 6 and 4), dated at 171 ± 22-ka and 68 ± 7-ka, respectively. From a topographical point of view, moraine M1 appears to be linked to the 60 m fluvioglacial terrace, dated in a tributary of the ragón iver at 263 ± 21-ka. The difference in age between 1 moraine and the 60 m fluvioglacial terrace suggests that the latter belongs to an earlier glacial stage ( 8). Moraine 2 was clearly linked to the fluvioglacial 20 m terrace. Other minor internal moraines were related to the 7–8 m terrace. The dates obtained for the last glacial cycle (20–18-ka) are similar to other chronologies for Mediterranean mountains, and confirm the occurrence of an early in the entral yrenees that does not coincide with the global .