Recent application of amino-acid racemization-epimerization to the dating of mixed-age marine deposits of central and southern Italy: age evaluation based on three amino-acid concentrations

Abstract

In this study, we rely on the ratio of D-alloisoleucine to L-isoleucine (aile/ile) in the genera Glycymeris collected from Pleistocene and Holocene mixed-age marine units. Amino Acid Epimerization (AAE) results are in good agreement with those obtained for the same sediments by 230Th/234U, and 14C. In the Montalto di Castro and Tarquinia areas, Latium (Central Italy), four marine mixed-age deposits were identified. Sampled sites are: S. Agostino Nuovo, Podere S. Pietro, Lestra delPOspedale and Bandita S. Pantaleo. The values obtained in these four deposits by ESR and 230Th/234U methods indicate a marine episode. The other mixed-age deposits identified are: S. Reparata in Sardinia; Manca della Vozza and Archi in Calabria (Southern Italy); Gallipoli in Apulia (Southern Italy; Milazzo in Sicily and Sapri in Campania (Southern Italy). From Manca della Vozza, a 230Th/234U dating was also performed. The analysis, which was carried out on Cerastoderma lamarcki cotronensis samples found at the same elevation (170 m a.s.l.) as the 8 Glycymeris insubricus samples, are in good agreement with those obtained by AAE, and put to evidence the mixed-age deposit. Most of AAE results have been published in previous works. From the Sapri deposit, which is examined for the first time in this paper with the Radiocarbon method, two analyses were made on the same Glycymeris spp. samples analyzed with AAE. In this deposit the radiocarbon dates also put to evidence two marine episodes, which are in good agreement with those obtained with AAE. Finally, the three component analysis technique provides important information on kinetic parameters and can be used to estimate the ages of Pleistocene to Holocene mollusks.