Yi H. H., Balan Etienne, Gervais C., Segalen L., Roche D., Person A., Fayon F., Morin G., Babonneau F. (2014). Probing atomic scale transformation of fossil dental enamel using Fourier transform infrared and nuclear magnetic resonance spectroscopy : a case study from the Tugen Hills (Rift Gregory, Kenya). Acta Biomaterialia, 10 (9), p. 3952-3958. ISSN 1742-7061.
Titre du document
Probing atomic scale transformation of fossil dental enamel using Fourier transform infrared and nuclear magnetic resonance spectroscopy : a case study from the Tugen Hills (Rift Gregory, Kenya)
Yi H. H., Balan Etienne, Gervais C., Segalen L., Roche D., Person A., Fayon F., Morin G., Babonneau F.
Source
Acta Biomaterialia, 2014,
10 (9), p. 3952-3958 ISSN 1742-7061
A series of fossil tooth enamel samples was investigated by Fourier transform infrared (FTIR) spectroscopy, C-13 and F-19 magic-angle spinning nuclear magnetic resonance (MAS NMR) and scanning electron microscopy (SEM). Tooth remains were collected in Mio-Pliocene deposits of the Tugen Hills in Kenya. Significant transformations were observed in fossil enamel as a function of increasing fluorine content (up to 2.8 wt.%). FTIR spectroscopy revealed a shift of the nu(1) PO4 stretching band to higher frequency. The nu(2) CO3 vibrational band showed a decrease in the intensity of the primary B-type carbonate signal, which was replaced by a specific band at 864 cm(-1). This last band was ascribed to a specific carbonate environment in which the carbonate group is closely associated to a fluoride ion. The occurrence of this carbonate defect was consistently attested by the observation of two different fluoride signals in the 19F NMR spectra. One main signal, at similar to-100 ppm, is related to structural F ions in the apatite channel and the other, at -88 ppm, corresponds to the composite defect. These spectroscopic observations can be understood as resulting from the mixture of two phases: biogenic hydroxylapatite (bioapatite) and secondary fluorapatite. SEM observations of the most altered sample confirmed the extensive replacement of the bioapatite by fluorapatite, resulting from the dissolution of the primary bioapatite followed by the precipitation of carbonate-fluorapatite. The nu(2) CO3 IR bands can be efficiently used to monitor the extent of this type of bioapatite transformation during fossilization.
Plan de classement
Sciences fondamentales / Techniques d'analyse et de recherche [020]
;
Géologie et formations superficielles [064]
