Granitoid stones from Calabria (Southern Italy): petrographic, geochemical and petrophysical characterization of ancient quarries of Roman Age

This paper reports the results of a petrographic, geochemical and petrophysical study ofgranitoid rocks from a Roman quarry close to the town of Parghelia (Calabria, southern Italy).Here, remnants of abandoned pillars and well preserved cuts testify that these materials wereemployed as building stones. The lithotypes cropping out in the Parghelia area consist of LateVariscan (~ 300 Ma) two-mica granitoids, occurring into two varieties: a dominant mediumcoarsegrained porphyritic granodiorite and a subordinate heterogranular granite. Thegranitoids from the quarry, for which we propose the term “Granito di Parghelia”, exhibit arestricted compositional range and distinctive petrographic characteristics, such as theoccurrence of K-feldspar megacrysts and white mica, that result useful for archaeometricpurposes. Moreover, ultrasonic investigation showed that Granito di Parghelia is characterisedby average velocity values of compressional waves ~ 4.0 km/s, widely ranging even atmesoscopic scale; this heterogenous mechanical behaviour is due to microfractures andmegacrysts distribution in the rocks. The above textural and physical features may providehelpful constraints in studies concerning the provenance and diffusion of granitoid rocksemployed in monuments of archaeological importance in southern Italy and may shed new light about the granite trade in the Mediterranean during the Roman age.