Magma storage and degassing beneath the youngest volcanoes of the Massif Central (France): Lessons for the monitoring of a dormant volcanic province

• Published in: Chemical geology 2023-09, Vol.634, p.121603, Article 121603
• Main Authors: Boudoire, G., Pasdeloup, G., Schiavi, F., Cluzel, N., Rafflin, V., Grassa, F., Giuffrida, G., Liuzzo, M., Harris, A., Laporte, D., Rizzo, A.L.
• Format: Article
• Language: English
• Subjects: Barometry; Earth Sciences; Fluid inclusions; Magma degassing; Monitoring; Noble gases; Sciences of the Universe
• ISSN: 0009-2541; 1872-6836
• DOI: 10.1016/j.chemgeo.2023.121603

Developing appropriate monitoring strategies in long-quiescent volcanic provinces is challenging due to the rarity of recordable geochemical and geophysical signals and the lack of experienced eruptive phenomenology in living memory. This is the case in the Massif Central (France) where the last eruptive sequence formed the Pavin's Group of Volcanoes, about 7 ka ago. There, current evidence of a mantle activity reminiscence is suggested by the presence of mineral springwaters, mofettes, and soil degassing. It appears fundamental as a prerequisite to decipher the evolution of the gas phase in the magmatic system at the time of the eruptive activity to understand the meaning of current local gas emissions. In this study, we develop an innovative approach coupling CO2 densimetry and geochemistry of fluid inclusions from products erupted by the Pavin's Group of Volcanoes. 3D imagery by Raman spectroscopy revealed that carbonate forming in fluid inclusions may lead to underestimation of CO2 density in fluid inclusions by up to 50% and thus to unreliable barometric estimates. Fortunately, we found that this effect may be limited by focusing on fluid inclusions with a small diameter (