Luminescence dating of Middle Pleistocene (MIS 7) marine shoreline deposits along the eastern coast of Tunisia: A comparison of K-feldspar and Na-feldspar IRSL ages

Abstract In the present study, we applied the IRSL 50°C dating method to both K- and Na-feldspar coarse grains from interglacial coastal deposits in north-eastern Tunisia. We used the yellow IRSL 50°C signal of Na-feldspars and the blue IRSL 50°C signal of K-feldspars. The key-sites for this study are at El Hajeb (Sahel area) and Dar Oufa (Cap Bon Peninsula). These deposits belong to the “Douira Unit” which has previously been assigned to marine isotope stage (MIS) 7 on the basis of amino acid ratios and chronostratigraphic evidence. In order to assess the reliability of the IRSL 50°C ages of the “Douira Unit”, we extended the IRSL dating technique to K- and Na-feldspars from two MIS 5 samples, with independent age control, collected within shallow-marine sands in the Sahel area and on the Jerba island (southern Tunisia). Two protocols of age correction for the observed fading in K- and Na-feldspars have been applied: (1) the Huntley and Lamothe (2001) fading correction and (2) the dose rate correction developed by Lamothe et al. (2003). The fading corrected IRSL ages of the “Douira Unit” and both MIS 5 control samples, measured on K- and Na-feldspars, are in good agreement with their expected ages.