Source area determination of aeolian sediments at Jandia Isthmus (Fuerteventura, Canary Islands)

Abstract

The Jandia Isthmus (Fuerteventura, Canary Islands) is a complex aeolian system composed of Pliocene and Pleistocene marine deposits, which are partially covered of carbonate crusts, palaeosols and sand sheets. The area has been greatly influenced by climate changes during the Quaternary. Nowadays this area presents an arid landscape dominated by the aeolian processes. Grain size, mineralogical and micropalaeontological analyses have been carried out to identify the source area of these wind-blown materials, considering five possible sources: windward beaches, Pliocene dune cliffs, Upper Pleistocene aeolian deposits, carbonate crusts and basaltic outcrops.

Each one of these analyses has been used to discriminate between the possible sources. Especially useful has been the use of foraminifera as natural tracers of the aeolian dynamics, as well as the application of the Rietveld method to quantify the mineralogical composition from the X-ray diffraction analysis (XRD). These techniques indicate that erosion of the Upper Pleistocene aeolian deposits — which partially cover the Isthmus surface — is the process that presently supplies most of the aeolian sediments that blow across the Isthmus. This study suggests the existence of extensive backshore surfaces westward of the present shoreline, during both the Pliocene and the Upper Pleistocene. This backshore was the original source area of aeolian materials transported by the Trade Winds, combined with the dust supply from Saharan desert.