Early Palaeolithic bone diagenesis in the Arago cave at Tautavel, France

Bones from level G in the Arago cave (Tautavel, Southern France, 450 ky) we re analysed using a combination of particle induced X-ray and gamma-ray emi ssion (PIXE and PIGME) and X-ray diffraction (XRD). Human occupation and gu ano production by bats introduced a large amount of phosphate into the cave and as a result a decarbonated pocket was formed in the sediment, characte rized by the dissolution of clay minerals, calcite and bones, and by the pr ecipitation of phosphate secondary minerals. The Al released by clay minera ls was reprecipitated as crandallite in the few remaining bones, and as mon tgomeryite with traces of crandallite in the surrounding sediments. Bones w ithin the pocket have very high levels of Al, Fe, F and Zn and often have ' diffusive' type U-shaped concentration profiles. These profiles show that p ost-mortem uptake of trace elements occurred, and thus that trace element c omposition has to be used with care in palaeonutritional studies but is ind icative of local palaeoenvironment. This uptake is complicated by a large i ncrease in hydroxylapatite crystallinity in Palaeolithic bones compared to modern or more recent ones, as a result of the large P influx which occurre d in the Arago cave after the sediment deposition.