Multidisciplinary fieldwork in the geothermal area Terme Caronte (Lamezia Terme-Calabria, Italy)

The Terme Caronte is located in the territory of Lamezia Terme city in Central Calabria (Southern Italy). This area was one of the test site in the VIGOR project framework. The Terme Caronte test site is characterized by several hot springs showing the presence of a hydrothermal resource with a deep circulation of water along fractures in Mesozoic rocks outcropping on the north portion of the Catanzaro Graben. The site was investigated by a multidisciplinary approach and geologists, geochemists and geophysicists worked defining the geological and hydrogeological deep structure. From geological and hydrogeological point of view, the investigated area is characterized by a small tectonic windows of Mesozoic carbonate rocks (high permeability), outcropping in Terme Caronte district, extruded within transpressional areas. The Calabride Complex (low permeability) is located above the previous one and represents a remnant of the Paleozoic basement, mainly outcropping in the Sila Massif. The terrigenous, evaporitic and carbonate mio-pliocenic sedimentary succession overlies the igneous-metamorphic basement of the Sila Unit and are strongly controlled by NWstrike-slip system, arranged in a right-hand en ´echelon pattern (Tansi et al., 2007). Several geochemical data were provided and some information on the origin and interactions of the circulating fluids were highlighted. The analysed data showed a normal thermal character of the investigated waters with a normal geothermal gradient (~30°C/km) allowing the existence of low to medium-enthalpy aquifers at a depth of about 1-3 km. The geothermometer for the Caronte system (SO4/F2 Marini et al., 1986) indicates a deep temperature in the range 55-65°C, confirming the low to medium enthalpy of the geothermal system as a whole. Finally, the investigated area misses deep borehole, therefore several deep indirect investigation were analysed. The geophysical work started from the analysis of previous seismic data available from ENI. New eep Geophysical data were acquired in the area: one Deep Electrical Resistivity Tomography and one MT profile. The DERT and the MT method define a multiscale tomography images of the subsoil, until 4 km. The EM data clearly highlight the contact between different electrical layers which should be associated to the geological formations. Moreover, the main structure associated to the geothermal system and the connection with the hot springs of Terme Caronte are detected, and a first geological and hydrogeological conceptual model was made.