This work is based on the evaluation and elaboration of already existing hydro-geochemical data collected by Istituto Nazionale di Geofisica e Vulcanologia – Palermo (INGV-PA) on behalf of the Regional Government of Sicily, that published the results on-line 3. Of all the many methodologies used to discover and characterize geothermal reservoirs ( IGA Service GMBH, 2014), those based on geochemical surveys are among the most useful and reliable ( D’Amore and Panichi, 1985 Nicholson, 1993). Our purpose was to provide basic information in order to identify areas where there is a greater chance of finding viable geothermal conditions to be considered for future exploitation. Exploitation of the local geothermal resources appears, therefore, of the utmost importance to provide both the population and the economic activities with a power source that is cheap, readily and widely available and with a low environmental impact, especially in a moment of world economic crisis mostly affecting the energy market. The area under study is important also because: (i) it is densely populated (almost one million people live there, distributed among thirty-five municipalities) (ii) it is the site of two of the largest industrials centers of southern Italy (iii) local land is used for many economic activities mostly related to agriculture (grapes, lemons, oranges, almonds, tomatoes, cheese, etc.). The origin of the gases in the most intense emission points was found to be mantle ( Bonfanti et al., 1993 Dall’Aglio et al., 1995 De Gregorio et al., 2002 Grassa, 2002 Giammanco et al., 2007). This sector of Sicily is today affected by several zones with focused gas emissions, diffuse degassing anomalies and thermal springs, in general associated with deep regional faults ( Bonfanti et al., 1993 De Gregorio et al., 2002 Grassa, 2002 Grassa et al., 2006 Giammanco et al., 2007). Our study has been focused on a south-eastern sector of Sicily, where volcanism has been active until middle Pleistocene and strong earthquakes have periodically occurred in historical times ( Barberi et al., 1974 Dall’Aglio et al., 1995). However, still a large portion of the Italian territory has not been investigated, despite of clear evidence of existing geothermal systems ( Minissale et al., 2019). There is a growing interest in Italy on studies regarding the recognition of geothermal areas and their potential in terms of possible exploitation ( Zervos et al., 2011). Geothermal resources range from shallow ground reservoirs to vapor- or water-dominated systems accessed by drilling wells down to thousands of meters below the Earth’s surface 1, 2 ( Bertani, 2012 Botteghi et al., 2012 Abate et al., 2014 Albanese et al., 2014). Geothermics is a clean and sustainable source of energy, as geothermal power plants involve no combustion, unlike classic thermal power plants, and thus they emit very low levels of greenhouse gasses. Finally, we mapped the factor scores obtained from PCA and we focused on those likely related with geothermal conditions in order to highlight the areas with the highest geothermal potential. We then applied Principal Component Analysis (PCA) to this restricted dataset and we were able to discriminate between different sources of solutes, both natural and anthropogenic. We identified and thence selected the most promising sites (water springs and wells) based both on their main geochemical characteristics and on their calculated equilibrium temperature (resulting in the range between 50 and 140☌). Today, though no active volcanism occurs, it is site of surface gas manifestations of focused degassing to which a mantle source has been attributed. The area was affected by volcanism until about 1.4 Ma. We analyzed a large dataset (143 water sampling sites, 22 variables) of chemical parameters in local groundwaters from the south-east sector of Sicily, namely the Hyblean plateau, in order to set an original evaluation of its geothermal potential using applied geochemistry. 2PH3DRA Laboratories (PHysics for Dating Diagnostic Dosimetry Research and Applications), Dipartimento di Fisica e Astronomia, Università di Catania & INFN Sezione di Catania, Catania, Italy.1Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, Sezione di Catania, Catania, Italy.Gloria Maria Ristuccia 1, Pietro Bonfanti 1, Salvatore Giammanco 1* and Giuseppe Stella 2
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