Evolution of the Late Pleistocene Aspe River (Western Pyrenees, France). Signature of climatic events and active tectonics

摘要

We make use of the cosmogenic nuclide ~(10)Be exposure to date an alluvial terrace of thernAspe River in the foothills of the northwestern Pyrenees. Initially ascribed to the Rissianrnglaciation, our dating shows that the terrace was abandoned at 18 u0002 2 kyr. In reference tornthe Late Pleistocene climatic chronology, two kinds of terraces can be distinguished: highstandingrnfill terraces probably deposited during glacial events and lower cut-in-fill and strathrnterraces cut during the postglacial river incision. A part of the terrace aggradations could havernoccurred during the Wu¨ rmian glacial episodes. Hence, the dated terrace fits in with thernprevailing view of incision during climate transitions. Our study also shows that elevation isrnnot a good criterion of terrace correlation, which should be better carried out on the basis ofrnabsolute dating. In addition, this dating also suggests a potential Late Pleistocene faultrnreactivation of the Mail Arrouy thrust in this tectonically active area of the Western Pyrenees.