Textural and geochemical evidence for the provenance of aeolian sand deposits on the Aquitaine coast, SW France

Abstract

Abstract The coastal dune system of the Aquitaine region, SW France, is the largest in Europe. At the present time the dunes are mostly stabilized by forest vegetation which is largely the product of dune stabilization schemes undertaken since the late 18th century. Much of the shoreline is currently eroding at rates of 1–2ma −1 , which are likely to increase if predictions of accelerated sea-level rise and increased storminess are correct. The sources of the beach and dune are poorly understood, and need to be identified in order to assess the sand budgets and likely dynamic response of the dune systems to changes in environmental forcing factors. This paper presents the results of an investigation to characterize the beach and aeolian sand in the region, and to identify its origin. The dune sands were found to be texturally and compositionally similar to the Quaternary Sable de Landes which occurs landward of, and partially beneath, the coastal dune belt. The results suggest that marine, aeolian and local fluvial reworking of the Sable de Landes has provided the main source of coastal dune sand, although marine erosion of Pleistocene deposits exposed in the coastal cliffs of the Medoc has made a secondary contribution.