Shallow portion of an active geothermal system revealed by multidisciplinary studies: The case of Le Biancane (Larderello, Italy)

Deep Regional Fluid Pathways in an Extensional Setting: The Role of Transfer Zones in the Hot and Cold Degassing Areas of the Larderello Geothermal System (Northern Apennines, Italy)

“…A recent paper, published by Granieri et al. (2023), highlighted some differences in the calculated CO 2 output in the Monterotondo area (encompassing both Monterotondo‐S and ‐N; i.e., 195 t d −1 km −2 ) than that computed by Cabassi et al. (2021) for Monterotondo‐S.…”

“…Nevertheless, when comparing the normalized CO 2 outputs obtained by Granieri et al. (2023), Cabassi et al. (2021), and this work no significant differences can be found since the amount of CO 2 from these areas are perfectly comparable when both Monterotondo areas (‐S and ‐N) are considered (i.e., ∼210 t d −1 km −2 ), hence, suggesting that the calculation procedures used in this and in the previous papers are correct.…”

“… (a) Map showing the main geological structures and geothermal manifestations occurring at the Larderello geothermal field; (b) dot‐map of the δ 13 C values of the CO 2 in natural emissions (data from Granieri et al., 2023; Hooker et al., 1985; Leila et al., 2021; Minissale et al., 1997; Panichi & Tongiorgi, 1975; Tassi et al., 2012; Venturi et al., 2019) and geothermal wells (Gherardi et al., 2005; Magro et al., 2003); (c) dot‐map of the Rc/Ra values measured in natural emissions (data from Hooker et al., 1985; Minissale et al., 1997; Magro et al., 2003) and geothermal wells (Gherardi et al., 2005; Hooker et al., 1985; Magro et al., 2003); (d) distribution of degassing rates computed in this work for central and peripheral areas. The black dashed lines circumscribe the location of most of the geothermal wells drilled in the area (after http://www.geothopica.igg.cnr.it/).…”

“…In the central areas and surroundings, the highest heat flux values of the Larderello geothermal area have been measured, reaching up to ∼1,000 mW m − 2 (Della Vedova et al, 2001), with soil temperatures reaching up to ∼98°C in correspondence with geothermal emergencies (Cabassi et al, 2021;Taussi et al, 2022). These conditions mainly occur along an NNE-striking fault zone, at least 5 km long, that runs from Monterotondo Marittimo to Sasso Pisano Granieri et al, 2023;Hooker et al, 1985;Leila et al, 2021;Minissale et al, 1997;Panichi & Tongiorgi, 1975;Tassi et al, 2012;Venturi et al, 2019) and geothermal wells (Gherardi et al, 2005;Magro et al, 2003); (c) dot-map of the Rc/Ra values measured in natural emissions (data from Hooker et al, 1985;Minissale et al, 1997;Magro et al, 2003) and geothermal wells (Gherardi et al, 2005;Hooker et al, 1985;Magro et al, 2003); (d) distribution of degassing rates computed in this work for central and peripheral areas. The black dashed lines circumscribe the location of most of the geothermal wells drilled in the area (after www.geothopica.igg.cnr.it).…”

“…To reconcile the information derived by the δ 13 C-CO 2 values of the interstitial gas and the soil CO 2 flux populations, both variables are plotted in Figure 11. In this figure, the δ 13 C of the CO 2 emitted from the main vent(s) collected in the studied areas (Libbiano: Panichi & Tongiorgi, 1975;Montemiccioli, Palazzo al Piano: Minissale et al, 1997;Sasso Pisano: Minissale et al, 1997;Tassi et al, 2012;Monterotondo: Venturi et al, 2019;Leila et al, 2021;Granieri et al, 2023) is reported as straight vertical bars. The δ 13 C-CO 2 ranges of the Larderello geothermal fluids (Gherardi et al, 2005), and other relevant geochemical features (Gianelli et al, 1997;Mason et al, 2017;Panichi et al, 1974;Sharp, 2017) are also plotted for comparison.…”