A hydrogeochemical approach to the characterization of low-enthalpy geothermal systems: the Scordia – Lentini graben (Sicily, Italy)

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Gloria Maria Ristuccia
https://orcid.org/0000-0001-5275-9682
Pietro Bonfanti
https://orcid.org/0000-0001-6846-0765
Salvatore Giammanco
https://orcid.org/0000-0003-2588-1441

Abstract




We describe the geochemical characteristics of groundwater samples collected in 23 water wells located on the northern margin of the Hyblean plateau (East Sicily). This area, mostly made of highly permeable carbonate rocks, is rich in low temperature (T < 50° C) hydrothermal groundwaters, distributed in an active sismogenetic zone, with several ENE-WSW-directed tectonic structures that drove magma to the surface during Upper Pliocene and Pleistocene. The chemical features suggest complex mixing between rainwater, CO2-rich groundwater, steam-heated groundwater and geothermal brines, as highlighted by Principal Component Analysis (PCA). Some parameters, however, indicate widespread pollution of the aquifers from human activities.


Stable isotopes analysis confirms the meteoric origin of groundwater and supports the origin of dissolved CO2 mostly from mantle degassing through deep tectonic faults. Geothermometric estimates, mostly based on quartz and Saturation Indexes geothermometers, suggest minimum reservoir temperature between 100 and 120° C.




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How to Cite
1.
Ristuccia GM, Bonfanti P, Giammanco S. A hydrogeochemical approach to the characterization of low-enthalpy geothermal systems: the Scordia – Lentini graben (Sicily, Italy). Ann. Geophys. [Internet]. 2021Nov.16 [cited 2022Jul.5];64(4):HS438. Available from: https://www.annalsofgeophysics.eu/index.php/annals/article/view/8536
Section
Physics of Hydrothermal Systems and Fluids in the Earth

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