GNGTS 2021 - Atti del 39° Convegno Nazionale

GNGTS 2021 S essione 3.2 442 Geology The structural and geological characteristics of Regalbuto area is strictly related with the tectonic evolution of theMediterranean basin and in particular of the central part of Sicily (Carbone et al. 2010). Regalbuto town is mainly underlain by the Terravecchia Formation (Fig. 1c). This latter consists of grey, grey-blue and greenish-grey marly-clays and clayey-marls, characterized by a flaky or laminated structure, with frequent yellowish-grey silty-sands and grey marls layers and localized polygenic conglomerate lens with heterometric rounded and sub-rounded clasts. Occasionally the Brecciated Clays are found in the Terravecchia Formation, which includes heterometric olistoliths of numidian quartz-arenites and the Argille Varicolori facies. The Brecciated Clays consists of grey-brown silty-clays and marly-clays with flaky and indistinct structure. Localized grey silty-sands and occasional angular to sub-angular polygenic gravels are also present. This sedimentary sequence is characteristic of continental shelf marine facies and delta plain. Themaximum thickness of the Terravecchia Formation is approximately 300 m and it dates back to the upper Tortonian stage (Carbone et al , 2010). Methodology The geophysical technique adopted in this study, called GPR (Ground Penetrating Radar), belongs to the non-invasive methods category, which allows to identify cavities, buried objects and structures and create models of the subsurface. This type of survey is based on the analysis of physical properties variations in the subsurface, in particular the dielectric permittivity, electric conductivity and magnetic permeability. Such electromagnetic properties variations may be related to various factors such as presence of buried objects, changes in the lithology or changes in the mechanical characteristics of the same lithotype (fractures and/or cavities). The data processing is carried out with modern software, which allow us to reconstruct 2D and 3D models of the subsurface structure. Fig. 2 - Planimetry of the church with the GPR scans location.