Dating of prehistoric caves sediments and flints using ¹⁰Be and ²⁶Al in quartz from Tabun Cave (Israel): Progress report

There is an important need to develop additional dating methods beyond the ¹⁴C limit and independent of thermoluminescence (TL) and electron spin resonance (ESR). We propose to apply the method of burial dating to prehistoric sites using the decay of in situ produced radioisotopes ¹⁰Be and ²⁶Al. The Tabun Cave, Mt. Carmel (Israel) has a sedimentary sequence which represents the type section for about the last 800,000 years in the Levant. The sediments in the cave are mainly of aeolian origin and are rich in quartz. Flint tools are also found in the sediments. Sediment samples and flint tools were selected from the same layer. Physical and chemical procedures to extract ¹⁰Be and ²⁶Al atoms from the quartz fraction of the sediments and from the flint samples were developed, while measuring the natural Al levels as a monitor of the atmospheric component of the cosmogenic nuclides. AMS measurements were performed at the 14UD Pelletron Koffler Accelerator Laboratory, Weizmann Institute, and sensitivities of the order of 1 × 10^-14, in isotopic abundances for both ¹⁰Be and ²⁶Al respectively (corresponding to ∼5×10⁵ atoms) were obtained. First, measurements of a number of Tabun Cave sediment samples and flints show that ¹⁰Be and ²⁶Al analyses have the potential for dating prehistoric cave sediments, provided problems relating to the presence of relatively large amounts of stable Al can be solved, as well as obtaining a better understanding of the burial history of the flints prior to being brought into the cave.