Constraining the timing of alluvial fan response to late quaternary climatic changes, southern Tunisia

The evolution of the Oued es Seffaia alluvial fan during the last 50,000 years is analyzed in the light of chronometric data derived from AMS radiocarbon and optical dating techniques. These ages have enabled the temporal constraint of the distalward progression of the intersection point (the upper limit of the locus of deposition) which has resulted in the telescopic segmentation of the fan. Comparison of these data with the Late Quaternary climatic history of the Maghreb highlights several problems of interpretation; due both to our limited knowledge of regional palaeoclimates and of the response of dryland fluvial systems to climate changes. However, our data provide some evidence to suggest that fan incision and formation of telescopic segments occurs in response to changes from arid to less arid conditions, supporting the conclusions of some of the work from other areas.