Composition chimique de quelques Mammifères fossiles d’un milieu continental phosphaté (Aubrelong I, Lot, France, Oligocène inférieur)

Fossil mammal long bones from Lower Oligocene from Aubrelong 1 (Quercy) were analysed for a range of elements using electron microprobe technique and infrared spectrometry. Fossil mammal teeth were analysed using electron microprobe technique. Comparison of the fossil samples is made with those of recent samples. Infrared spectra show the decrease and the alteration of the organic matrix content in fossil bones. Values for the elements P, Ca are significantly higher, and S lower in the fossil samples relative to the recent samples. The high concentrations of these elements in the fossil samples are clearly a result of diagenetic alteration. In most fossil sites, all the tissues are enriched in Ca, P contents being higher or lower than in the recent tissues. All the fossil tissues of the Aubrelong site are enriched in P. Thus one may tentatively conclude that there is a relationship between the phosphatic composition of sediment and the behavior of P. The chemical composition of all the fossil tissues seems to converge. The organic and the mineral phases are altered by diagenetic processes.