Preprints
https://doi.org/10.5194/egusphere-2024-1306
https://doi.org/10.5194/egusphere-2024-1306
22 May 2024
 | 22 May 2024
Status: this preprint is open for discussion.

Revised conceptual model of the Solfatara magmatic-hydrothermal system (Campi Flegrei, Italy), time changes during the last 40 years, and prediction of future scenarios

Luigi Marini, Claudia Principe, and Matteo Lelli

Abstract. We revised the conceptual model of the Solfatara magmatic-hydrothermal system based on the results of new gas-geoindicators (Marini et al., 2022) and the available geological, volcanological, and geophysical information from surface surveys and deep geothermal wells. Using the new gas-geoindicators, we monitored the temperature and total fluid pressure over a time interval of ~40 years: (i) in the shallow reservoir (0.25–0.45 km depth), where CO equilibrates; (ii) in the intermediate reservoir (2.7–4.0 km depth), where CH4 attains equilibrium; (iii) in the deep reservoir (6.5–7.5 km depth), where H2S achieves equilibrium. From 1983 to 2022, the temperature and total fluid pressure of the shallow reservoir did not depart significantly from ~220 °C and ~25 bar, whereas remarkable, progressive increments in temperature and total fluid pressure occurred in the intermediate and deep reservoirs, with peak values of 590–620 °C and 1200–1400 bar in the intermediate reservoir and 1010–1040 °C and 3000–3200 bar in the deep reservoir, in 2020. The revised conceptual model allowed us to explain the evolution of: (a) pressurization-depressurization in the intermediate reservoir, acting as the “engine” of bradyseism, (b) time changes of total fluid pressure in the deep reservoir, working as the “on-off switch” of magmatic degassing. We also used the revised conceptual model to predict possible future scenarios in the lack of external factors.

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Luigi Marini, Claudia Principe, and Matteo Lelli

Status: open (until 09 Jul 2024)

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Luigi Marini, Claudia Principe, and Matteo Lelli
Luigi Marini, Claudia Principe, and Matteo Lelli

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Short summary
We revised the conceptual model of the Solfatara magmatic-hydrothermal system and we used new geothermometers and geobarometers, specifically calibrated for the Solfatara fluids, to monitor temperature, T, and total fluid pressure, P, in three distinct reservoirs at different depths, over ~40 years. The T, P changes in the intermediate reservoir (at 2.7–4 km depth) are of utmost interest because its pressurization-depressurization acts as the “engine” of bradyseism currently affecting the area.