A multi-analytical study of bone diagenesis: the Neolithic site of Bercy (Paris,France)

Abstract

Bone remains play an important role in archaeology as a source of informationabout the past. However, they alter over time. Alteration occurs at all scales fromthe macroscopic to nanoscopic level. The evaluation of information extracted onpalaeodiets, ages and palaeoclimates from their chemical and isotopiccomposition requires the study of diagenetic modifications by means of differentcomplementary analytical methods. Diagenetic parameters that quantifythe post-mortem alteration of bone are bone histology, porosity, proteincontent, crystallinity of bone apatite, carbonate content, enrichment andleaching of chemical species in general. The investigation of these featurescan be performed by a combination of complementary elemental andstructural analyses (particle-induced x-ray emission, particle-induced γ-rayemission, scanning electron microscopy (SEM) coupled with energy dispersivex-ray (EDX), electron microprobe, x-ray diffraction, infrared spectroscopy,transmission electron microscopy (TEM) with EDX), microscopic observations(optical, SEM, TEM) and porosity measurements.The study of animal bonesfrom the Neolithic site of Bercy, France (4000 BC) from the same archaeologicallayer within different local depositional, hydrological and redox environmentsillustrates the possible information that can be extracted from the diageneticstudy on the processes affecting the state of bone preservation. The maincharacteristic of the bone buried in the waterlogged zone is a high level ofpreservation of the organic matter and a low level of porosity inhibitingmajor structural or chemical modifications. The bone sample from thezone with a fluctuating hydrological regime shows a low level of organicmatter and high porosity. Knowledge of the diagenetic patterns enables anestimation of the reliability of information obtained from bone analyses.