The archaeological site of St. Maria Veterana (Triggiano, Southern Italy): Archaeometric study of the wall paintings for the historical reconstruction

This paper focusses on the archaeometric investigation of wall paintings of the St. Maria Veterana archaeological site in Triggiano (Bari, Southern Italy) finalised to support the hypothesis on the historical reconstruction of the site based on iconographic interpretations. The site is an original and relevant example of medieval art in Apulia and in Southern Italy and includes a medieval church surrounded by several additionally architectural elements (chapels, crypts, tombs), nowadays buried below by a Renaissance church. Here, the presence of different pictorial cycles, only partially dated, and the evidence of re-use of painted blocks in Renaissance structures pertaining to medieval structures, suggested a complex scenario in which different artisans and clients were possibly succeeded. The site is also framed in a wider regional context, the Apulian region, currently object of an intense archaeological and scientific debate due to widespread action of valorisation of the cultural patrimony as an essential link between the territory and the cultural identity of the citizens. The study of the site involved the sampling and the analysis of 48 samples of painting fragments, investigated by optical microscopy, scanning electron microscopy with EDS microanalysis (SEM-EDS) and micro-Raman spectroscopy. The obtained results allowed a complete material characterization of mortars and pictorial layers, highlighting the use of precious and rare pigments as cinnabar and verdigris, along with more common recipes based on natural ochres and earths more commonly used in other similar sites through the Apulia region. The combined data obtained from the analysis of mortars and pigments allowed to finally propose a reliable hypothesis on the construction and decorative phases of the site, in agreement with the dating based on iconographic interpretations. Up to now, St. Maria Veterana Church was considered a minor site, mainly due to the scarcity of the written sources. However, the new stylistic interpretation of the pictorial cycles, the preciousness of the used materials, the quality of the manufacture technique and the numerous artistic executive phases identified through five centuries (11th–16th) suggest a continuous attendance of the site by artisans and client carriers of high cultural and artistic values.