Unveiling the origins: Multi-analytical study on the provenance determination of white marble from the ecclesiastical complex of Beati Severi basilica in Classe (Ravenna, Italy)

The strategic role of Ravenna (Italy) in the northwestern Adriatic became particularly evident in the early fifth century, when it assumed the role of a sedes imperii and developed into a key center of the Western Roman Empire. This prominence was significantly supported by its seaport Classis, which functioned as one of major hubs for the trade and cultural exchange across the Mediterranean. In the past, the precious marble artefacts in Ravenna and its artistic circuit were described exclusively from stylistic and typological points of view, with no scientific methods employed for determining provenance. This study presents the results of a multi-analytical investigation into fifteen white marble samples, representative of the late antique and early medieval contexts of the ecclesiastical complex of Beati Severi Basilica in Classe. To determine the provenance of the marble, a combination of mineralogical-petrographic techniques (including polarizing, cathodoluminescence and electron microscopy, as well as X-ray powder diffraction) and geochemical methods (stable carbon and oxygen isotope analysis and trace element content via ICP-MS) was employed. The geochemical data were processed using discriminant analysis and compared with reference datasets from known ancient quarries. Most calcitic samples were identified as Proconnesian marble. The remaining calcitic samples were attributed to Aphrodisias, Dokimeion, and Thassos-Aliki (Thassos-2). Two dolomitic samples were attributed to the Cape Vathy/Saliara (Thassos-3), although without statistical evaluation. For the studied marble samples, the most diagnostic factors for provenance determination were a combination of microscopic features (microfabric, grain size, mineral composition, and CL microfacies), carbon and oxygen isotope ratios, and trace element contents – primarily Mn, Sr, Y + REEs, and Pb. Although the combination of the aforementioned methods proved the generally accepted hypothesis that the Ravennate marbles originated from the Proconnesos quarries, it also revealed that these were not the only source. The provenance determinations of marble, imported to Ravenna and Classe in Late Antiquity and reused in the Middle Ages, offers critical insight into the city’s role within Mediterranean trade and cultural networks. It further underscores Ravenna’s orientation towards the Eastern Mediterranean, and its function as a redestribution centre in the broader regional context.