Dating of late Pleistocene and Holocene fluvial sediments Using OSL, Uranium series and 14C methods in the Saqqez River,

Fluvial sediment dating surveys are one of the quaternary researches which can help to explicit many environmental issues. In the present study, samples taken to direct age determination belong to a depositional profile located in one of the tributaries of Saqqez River. This profile is located at southwest of Saqqez city and at the outlet of Saqqez basin. The OSL method was used to determine the age of three samples including sandy lens, floodplain and conglomerate sediments. 14C and U/Th methods was applied to dating of the charcoal in conglomerate sediments and pedogenic/ cement carbonates respectively. The age of the unit is constrained by OSL dating of a sandy lens, at the base of the profile, at 68.35±9.50 ka and the overlying floodplain deposits at 26.76±6.96 ka (i.e. Late Pleistocene). Floodplain consolidated sediment (conglomerate) has been OSL dated at 5.79±1.88 ka which belongs to Mid-Holocene period. Concerning the fluvial sediments ages by the U/Th method, it should be noted that since the ratio of thorium to uranium was much higher than its standard value in both pedogenic and cement carbonate samples, it is not possible to determine the age of carbonate samples using the uranium series method. The calendar age reported by 14C is around 1995, looks enigmatic considering the context from which the sample has been collected and the time required for crystallization of the enclosing carbonate cements. Therefore, it seems that among the different methods of fluvial sediment absolute dating methods, luminescence is more suitable for quaternary fluvial sediments dating in Saqqez River basin