Pompeii AD 79: A Natural Bone Diagenesis Experiment

Abstract

AbstractThis study aims at comparing the reliability of different types of apatite fractions for which collagen cannot be dated. We focused on the remains of individuals found at the necropolis of Porta Nocera near Pompeii, and for which the date of burial can be assessed independently. The dated human samples range between 1805±49 and 5570±120 14C yr BP and can display a large (up to 1200 14C yr) intra-individual age variability. We show that while a marine diet or an old-wood effect could explain the smallest age shifts, they are not able to explain the largest ones, and propose diagenesis as the main cause. The 14C depletion is likely due to the influence of the 14C-free CO2 emissions of the nearby Vesuvius volcano and the Campi Flegrei volcanic system on the age of secondary carbonate incorporated into the bone and enamel crystallites during diagenesis. This study demonstrates that in volcanic contexts, a large deviation from expected age can be measured, even in calcined apatites. Our calculations indicate that while the absolute amount of contamination is lower in calcined bones than in burnt bone and enamel apatite, its impact on the 14C age of the sample can be much higher due to the low carbon content of calcined bones.