Chronology and formation processes of the Middle to Upper Palaeolithic deposits of Ifri n'Ammar using multi-method luminescence dating and micromorphology

Abstract

The existence of an early Upper Palaeolithic culture at the transition from the Middle Palaeolithic to the Upper Palaeolithic in North African cave sites is currently under debate. We studied Ifri n‘Ammar in North-East Morocco, which is one of the oldest settlement sites of anatomically modern humans (AMH) in the Maghreb and contains several sediment layers which are attributed to Middle and Upper Palaeolithic occupations. In order to investigate processes of sediment accumulation and postdepositional alteration, we studied thin sections from these levels. According to micromorphological analysis, aeolian input considerably contributed to sediment accumulation and postdepositional mixing by bioturbation occurred. We compared multiple and single-grain quartz and multiple-grain feldspar luminescence dating of three samples from corresponding sediment layers to achieve a comprehensive chronology. The single-grain dose distributions scatter strongly and the source of the scatter is unclear. We used an arithmetic mean to calculate the equivalent doses. Archaeological evidence and age control from radiocarbon dating was essential to interpret the data. Quartz and feldspar multiple-grain luminescence ages are between 15 and 80 ka. The central part of the profile shows an intermediate accumulation, which lacks specified lithic artefacts. This supports the idea of an occupational gap between Middle and Upper Palaeolithic layers.