Study of the Mortars from the St. George’s Cathedral in the Yuryev Monastery (Veliky Novgorod) Based on Neutron Activation Analysis Data

Dating is one of the most important tasks in archaeology. Studies of elemental composition using neutron activation analysis, combined with statistical data treatment, enable the establishment of indirect dating for the investigated artifacts. In this study, 11 mortar samples were studied. The samples were collected from buildings located on the territory of the Yuryev Monastery (Veliky Novgorod, Russia). For irradiation, the IREN facility at Joint Institute for Nuclear Research (Russia) and the WWR-K reactor at Institute of Nuclear Physics (Kazakhstan) were used. Using neutron activation analysis, mass fractions of 34 chemical elements were obtained. By applying multivariate statistical methods (hierarchical cluster analysis, principal component analysis, and factor analysis), it was established that the elemental composition of mortars from various historical periods differs significantly. This enabled the identification of groups corresponding to specific historical periods. It was shown that the content of rare earth elements in samples dating back to the pre-Mongol period is elevated compared to samples with later dating. The obtained data enabled the classification of samples with unknown dating using the method of indirect dating.