Carbon 14 dating of some materials found during the excavation of the catacomb of san gennaro in naples: Old research and new data

The review of an old14C dating investigation and the new radi-ometric analysis on 10 different samples, conducted by the Center for Isotopic Research on Cultural and Environmental heritage (CIRCE) of the University of Campania “Luigi Vanvitelli”, through the AMS (Accelerator Mass Spectrometry), offer useful elements to date the excavation and relative phases of the catacomb of St. Ianuarius, the most important Late Antique cemetery in Naples. Several excavations have been carried out in the catacomb since the nineteenth century, not always conducted in a systematic manner and published only in part. In the last decade, the Pontifical Commission for Sacred Archeology has started the edition of the old excavations and finds, thanks also to the archaeometric analysis. The recalibration of a previous measurement of a beam fragment discovered during the excavations carried out in the 1970s, based on the new IntCal 13 Calibration Curve and the Oxcal Software 4.3, allowed the finding to be more correctly dated to 530-659 A.D. (±2σ). The AMS reduces not only the14C isotopic measurement time but also the weight of the material used for dating. Furthermore, advances in chemical treatments on samples of different nature make it possible not only to quantify radiocarbon in a wider range of organic materials but also, through an innovative calcite extraction process, dating from mortars (first mortar radiocarbon dating of the catacombs analyzed). The results obtained in this study expand our knowledge on the catacomb not only in Late Antiquity and in the Middle Ages, but also in the following centuries (see the dating of the samples Sgn 1, Sgn 2, Sgn 3, Sgn 6).