TY - JOUR T1 - The 2018-ongoing Mayotte submarine eruption: Magma migration imaged by petrological monitoring A1 - Berthod,Carole A1 - Médard,Etienne A1 - Bachèlery,Patrick A1 - Gurioli,Lucia A1 - Di Muro,Andrea A1 - Peltier,Aline A1 - Komorowski,Jean-Christophe A1 - Benbakkar,Mhammed A1 - Devidal,Jean-Luc A1 - Langlade,Jessica A1 - Besson,Pascale A1 - Boudon,Georges A1 - Rose-Koga,Estelle A1 - Deplus,Christine A1 - Le Friant,Anne A1 - Bickert,Manon A1 - Nowak,Sophie A1 - Thinon,Isabelle A1 - Burckel,Pierre A1 - Hidalgo,Samia A1 - Kaliwoda,Melanie A1 - Jorry,Stephan A1 - Fouquet,Yves A1 - Feuillet,Nathalie AD - Université Clermont-Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, 6 avenue Blaise Pascal, 63178 Aubière, France AD - Observatoire Volcanologique du Piton de la Fournaise, Institut de physique du globe de Paris, F-97418 La Plaine des Cafres, France AD - Université de Paris, Institut de physique du globe de Paris, CNRS, F-75005 Paris, France AD - CNRS, Ifremer c/Brest, F-29280 Plouzané, France AD - BRGM-French geological survey, 3 avenue Claude Guillemin, BP36009, F-45060 Orléans, Cédex 2, France AD - Ludwig-Maximilians-Universität München, Theresienstrasse 41, D-80333 München, Germany AD - Ifremer, GM, F-29280 Plouzané, France UR - https://doi.org/10.1016/j.epsl.2021.117085 DO - 10.1016/j.epsl.2021.117085 KW - Mayotte KW - submarine eruption KW - dredges KW - petrological model KW - mantle reservoirs KW - multiple storage zone N2 - Deep-sea submarine eruptions are the least known type of volcanic activity, due to the difficulty of detecting, monitoring, and sampling them. Following an intense seismic crisis in May 2018, a large submarine effusive eruption offshore the island of Mayotte (Indian Ocean) has extruded at least 6.5 km3 of magma to date, making it the largest monitored submarine eruption as well as the largest effusive eruption on Earth since Iceland's 1783 Laki eruption. This volcano is located along a WNW-ESE volcanic ridge, extending from the island of Petite Terre (east side of Mayotte) to about 3,500 m of water depth. We present a detailed petrological and geochemical description of the erupted lavas sampled by the MAYOBS 1, 2, and 4 cruises between May and July 2019 and use these to infer characteristics and changes through time for the whole magmatic system and its dynamics from the source to the surface. These cruises provide an exceptional time-series of bathymetric, textural, petrological, and geochemical data for the 2018-2019 eruptive period, and hence bring an invaluable opportunity to better constrain the evolution of magma storage and transfer processes during a long-lived submarine eruption. Integrating the petrological signatures of dredged lavas with geophysical data, we show that the crystal-poor and gas-rich evolved basanitic magma was stored at mantle depth (>37 km) in a large (≥10 km3) reservoir and that the eruption was tectonically triggered. As the eruption proceeded, a decrease in ascent rate and/or a pathway change resulted in the incorporation of preexisting differentiated magma stored at a shallower level. Magma transfer from the deep mantle reservoir is syn-eruptive, as indicated by transfer times estimated from diffusion in zoned olivine crystals that are much shorter than the total eruption duration. Our petrological model has important hazard implications concerning the rapid and stealthy awakening of a deep gas-rich magma reservoirs that can produce unusually high output rates and long-lived eruption. Sudden tapping of large crystal poor reservoirs may be the trigger mechanism for other rarely witnessed high-volume (>1 km3) effusive events. Y1 - 2021/10 PB - Elsevier BV JF - Earth And Planetary Science Letters SN - 0012-821X VL - 571 ID - 82273 ER -