New geological insights and structural control on fluid circulation in La Fossa cone (Vulcano, Aeolian Islands, Italy)

Stéphanie Barde-Cabusson (1, 2) , Anthony Finizola (3, 4, 5) , A. Revil (6, 7) , T. Ricci (4) , S. Piscitelli (8) , E. Rizzo (8) , B Angeletti (9, 10) , M. Balasco (8, 11) , L. Bennati (1, 12) , S. Byrdina (1, 5) , N. Carzaniga (13) , Agnès Crespy (9) , F. Di Gangi (14) , J. Morin (5, 15) , A. Perrone (8, 11) , M. Rossi (16, 17) , E. Roulleau (18) , B. Suski (19) , Nicolas Villeneuve (20)

1 LMV - Laboratoire Magmas et Volcans
2 DST - Dipartimento di Scienze della Terra [Firenze]
3 LGSR - Laboratoire GéoSciences Réunion
4 INGV - Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma
5 IPGP - Institut de Physique du Globe de Paris
6 Department of Geophysics [Golden CO]
7 LGIT - Laboratoire de Géophysique Interne et Tectonophysique
8 Hydrogeophysics Laboratory
9 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement
10 International Institute of Earthquake Engineering and Seismology
11 Laboratory of Geophysics
12 Department of Earth and Atmospheric Sciences [West Lafayette]
13 Department of Geology and Geosciences
14 INGV - Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo
15 UP1 - Université Paris 1 Panthéon-Sorbonne
16 Dipartimento di Geoscienze [Padova]
17 UNIMIB - Università degli Studi di Milano-Bicocca = University of Milano-Bicocca
18 GEOTOP - Centre de recherche sur la dynamique du système Terre
19 Institut de Geophysique
20 Institut de Recherche pour le Développement, US 140 ESPACE, La Réunion, France

Accepted 1 June 2009 Available online 21 June 2009 Keywords: electrical resistivity self-potential soil CO2 degassing temperature fluid circulation hydrothermal system structural boundary Vulcano La Fossa cone Electric resistivity tomography (ERT), self-potential (SP), soil CO2 ux, and temperature are used to study the inner structure of La Fossa cone (Vulcano, Aeolian Islands). Nine profiles were performed across the cone with a measurement spacing of 20 m. The crater rims of La Fossa cone are underlined by sharp horizontal resistivity contrasts. SP, CO2 flux, and temperature anomalies underline these boundaries which we interpret as structural limits associated to preferential circulation of fluids. The Pietre Cotte crater and Gran Cratere crater enclose the main hydrothermal system, identified at the centre of the edifice on the base of low electrical resistivity values (b20 Ω m) and strong CO2 degassing, SP, and temperature anomalies. In the periphery, the hydrothermal activity is also visible along structural boundaries such as the Punte Nere, Forgia Vecchia, and Palizzi crater rims and at the base of the cone, on the southern side of the edifice, along a fault attributed to the NWmain tectonic trend of the island. Inside the Punte Nere crater, the ERT sections show an electrical resistive body that we interpret as an intrusion or a dome. This magmatic body is reconstructed in 3D using the available ERT profiles. Its shape and position, with respect to the Pietre Cotte crater fault, allows replacing this structure in the chronology of the development of the volcano. It corresponds to a late phase of activity of the Punte Nere edifice. Considering the position of the SP, soil CO2 flux, and temperature maxima and the repartition of conductive zones related to hydrothermal circulation with respect to the main structural features, La Fossa cone could be considered as a relevant example of the strong influence of preexisting structures on hydrothermal fluid circulation at the scale of a volcanic edifice.

Mots clés: Vulcano; La Fossa cone.; fluid circulation; hydrothermal system; structural boundary; soil CO2 degassing; temperaturefi; La Fossa cone; self-potential; electrical resistivity

Domaines: Volcanologie

Stéphanie Barde-Cabusson, Anthony Finizola, A. Revil, T. Ricci, S. Piscitelli, et al.. New geological insights and structural control on fluid circulation in La Fossa cone (Vulcano, Aeolian Islands, Italy). Journal of Volcanology and Geothermal Research, 2009, 185 (3), pp.231-245. ⟨10.1016/j.jvolgeores.2009.06.002⟩. ⟨insu-00446813⟩