Chronology of the late Lower and Middle Palaeolithic at Tabun Cave (Mount Carmel, Israel) with insights into diagenesis and dose rate variation using post-IR IRSL (pIRIR290) dating and infrared spectroscopy
Tabun Cave, located on the slopes of Mount Carmel (Israel), constitutes one of the key Levantine Palaeolithic sites because of its exceptionally long sequence (ca. 25 m) that has yielded a suite of lithic industries spanning the Lower and Middle Palaeolithic periods. This site is also known to have produced human remains found in the Middle Palaeolithic layers: a Neanderthal female skeleton (C1), and a mandible (C2) commonly classified as Homo sapiens but whose attribution is still debated. Determining the chronology of Levantine Palaeolithic caves has often been limited by severe diagenetic processes, affecting the accuracy of age results obtained using trapped-charge dating methods. Characterising the mineralogical composition of the sediments in such conditions is an important step that was done in this study using Fourier transform infrared (FTIR) spectroscopy. We show that most of our sediment samples underwent diagenesis from the decomposition of guano, ash or bones, based on the presence of authigenic phosphates, which may impact the dose rate. Considering this information, we report here age results obtained using post-infrared infrared stimulated luminescence (pIRIR290) of polymineral fine grains for Tabun Cave. Our pIRIR290 ages are in overall agreement with thermoluminescence (TL) dating results obtained previously on burnt flints, reinforcing the antiquity of key transitions in the Middle Pleistocene record from Tabun Cave. The ages suggest that the Lower to Middle Palaeolithic transition at Tabun, possibly coinciding with the arrival of Homo sapiens in the Levant, may be constrained between 265 ± 26 ka (late Lower Palaeolithic, Bed 72, Unit X) and 288 ± 29 ka (early Middle Palaeolithic, Beds 63–64, Unit IX), while the age of the base of the overlying mid-Middle Palaeolithic Layer C (Unit I; Beds 22-19) ranges between 204 ± 18 ka and 192 ± 14 ka. Consequently, the Tabun C2 mandible discovered at the base of Layer C may prove to be among the oldest Homo sapiens fossils found outside Africa.
