GEOCHEMICAL AND GEOPHYSICAL RESEARCH AIMED AT CHARACTERIZING THE HYDRO-GEOLOGICAL STRUCTURES OF A KARST FORMATION

Geochemical and geophysical research was effected in an area between the Madonia mountain range and the coast around the Rock of Cefalù, at the base of which there are a number of large-sized springs. The aim of the study was to reconstruct the buried hydro-geological structures that carry the waters from the Madonia Mountains to the areas along the coast where they surface. The Madonia Mountains are prevalently made up of carbonatic formations and terrigenous deposits of the Numidian Flysch. Outcrops of the Cozzo Terravecchia formation are also present, as are Messinian evaporitic deposits and recent detritic deposits of alluvial and marine origin. The Karst processes that develop in the limestone of the Panormid Unit, have a predominant role in the geo-morphological and hyro-geological structure of the area. A model of the subterranean circulation of the waters was built by means of hydro-geochemical and geophysical investigations. The research was carried out using integrated geophysical methods in order to obtain a three-dimensional model of the structures under investigation. Geophysical data obtained from previous studies were used, as were electrical survey data (SEV) and electro-magnetic survey data (TDEM). The model we obtained (for which the spatial distribution of the uncertainties of the estimation of some parameters was also calculated), shows characteristics that are compatible with the main geological-structural evidence of the area and identifies the presence of carbonatic rocks below the Numidian Flysch. These rocks are able to carry the waters that infiltrate down from the high Madonia Mountains to the area named Presidiana on the Cefalù coast where they surface.