Limestones in the Roman Architecture of Oderzo and Concordia Sagittaria (Italy): Petrography and Provenance

This paper presents the results of a research project on the use of stone in Roman architecture in Oderzo and Concordia Sagittaria, located between the Tagliamento and the Piave rivers (Italy). The study involved a documental survey, material sampling and analysis, provenance identification, and interpretation of results to reconstruct ancient stone trade routes. During sampling, 33 carbonate rock specimens were collected from archaeological sites and architectural elements in Oderzo, and 52 from Concordia Sagittaria. In both cities, these rocks were primarily used for architectural elements such as columns and capitals, whereas these lithotypes were less frequently employed in structures and infrastructures. The analysis revealed a significant reliance on regional limestones. Petrographic examinations (PLM-TL) identified six main limestone groups, many of which were linked to quarries located in the Aurisina and in the Triestine Karst region, as well as in the Prealps and Berici Hills. The study encountered several challenges: many analysed samples displayed petrographic characteristics consistent with multiple sources, complicating the precise identification of their extraction site. Despite a detailed understanding of the region’s geology, reference geological datasets often overlook outcrops that may have been exploited in antiquity. Consequently, when samples lacked distinctive features, tracing them to a particular quarrying basin proved difficult. In conclusion, the research underscores the extensive use of local limestones while acknowledging the challenges posed by limited petrographic reference data, which hinder the precise identification of the source basins of the materials used in Roman construction.