Dating of palaeoanthropological nuragic skeletal tissues using electron paramagnetic resonance (EPR) spectrometry.

Dating of skeletons of Nuragic population living in Sardinia island centuries BP, based on the quantitative evaluation of the concentration of stable paramagnetic species produced by ionising radiation in tooth enamel was performed by using EPR spectrometry. Applying the additive dose method (60Co gamma rays) and comparative calculations based on analogous measurements done with Roman skeleton of the known age as discovered close to Nuragic tomb (Tombs of Giants, La Testa S. Teresa di Gallura, Sardinia) the age of Nuragic skeleton was evaluated as equal to about 3,200 years (1,200 years BC). The total error of EPR measurements and dose extrapolation was estimated for 10-12%. Crystallinity of bone mineral in Nuragic skeleton evaluated by the EPR technique, adapted earlier by some of the authors of the present paper for biomedical studies on mineralised tissues, is only little changed after the centuries of its deposition in the tomb when compared with contemporary bone tissue. Comparison of chemical composition of Nuragic skeleton contaminated through slow percolation by rain of floods with that of contemporary bone sample shows the increase of the concentration of Fe, PO4, SiO2, Al and Mg, Fe, SiO2, AP are not present in contemporary bones. As expected, the contamination was minimal in tooth enamel.