Geochemical and petrographic analysis on the stones and integrated digital survey of the Cathedral of Sant'Antioco di Bisarcio (Ozieri, Italy)

The medieval Cathedral of Sant'Antioco di Bisarcio is one of the most important Romanesque churches in Sardinia. The countryside church is located on a volcanic hill in the area of Chilivani (Ozieri, north Sardinia). It was built with local Eocene-Miocene pyroclastites at the beginning of the XI century by Tuscan-Lombard workforce, according to three constructive phases, which reveal specific features both in terms of architecture and in relation to the use of building materials, represented by several pyroclastic rocks. The collected results of geochemical-petrographic analysis on the volcanic rocks and 3D Laser Scanner survey of ancient building, together with a historical research, have shed light on the provenance and alteration of geomaterials, the evolution and the mutilations suffered by the church at later times; among these it can be distinguished the opening of a mullioned window, which was the starting point of our specific focus on the elements of the capital and the original 'pulvino'. The study of these elements was conducted through surveys and digital photogrammetry techniques.