RECENT VOLCANISM NEAR MAYOTTE ISLAND

In April-May 2018 a strong seismic crisis shook the island of Mayotte, a French overseas territory in the Indian Ocean. In May 2019, scientists aboard a follow-up cruise (Mayobs) described the largest effusive eruption since Laki in 1000 (Feuillet et al. 2021). The eruption lasted from mid-2018 to at least late 2020 / early 2021 and erupted more than 7 km3 of basanitic magma. A number of monitoring and research cruises (Mayobs cruises, Geoflamme, Scratch) have since extensively sampled the seafloor of the previously unknown submarine volcanic province offshore Mayotte. I am involved with a number of colleagues in the petrological, geochemical and volcanological analysis of the erupted products of recent eruptions, and their implications for hazard evaluation.

Some collaborators (partial list):
* UCA : Lucia Gurioli, Tristan Lacombe (PhD student), Pauline Verdurme (PhD student), Patrick Bachèlery, Oryaelle Chevrel, Emma Chaudron (master student), Théo Hassen-Ali (master student)
* IPGP : Carole Berthod, Jean-Christophe Komorowski, Pascale Besson, Charles Le Losq, Nathalie Feuillet
* LGL : Andrea Di Muro

FANI MAORE SUBMARINE VOLCANO

I have recalibrated an accurate Al-in hornblende barometer from experimental litterature data on rhyolites (Médard and Le Pennec, submitted). This new barometer takes into account the effect of both edenite and Tschermack substitutions on Al concentrations. Existing litterature data show a very good pressure-dependence of the Tschermack substitution (correlation coefficient of 0.95) for amphibole in equilibrium with biotite, plagioclase and quartz. Our new barometer reproduces experimental pressures with an average error of 58 MPa (equivalent to a depth of 2.2 km) in the 100-400 MPa range. More experiments are underway to improve the barometer’s accuracy. Compared to previous barometers, this new calibration is independent of temperature, and gives a much better resolution for magma chamber depth.

Collaborators: Philipson Bani, François Nauret, Estelle Rose-Koga, Yves Moussallam, Kenneth Koga, Christy Harruel (PhD student)

Moussallam Y, Médard E, Georgeais G, Rose-Koga EF, Koga KT, Pelletier B, Bani P, Grandin R, Boichu M, Shreve TL, Tari D, Peters N (submitted) How to turn off a lava lake? A petrological investigation of the 2018 intra-caldera and submarine eruptions of Ambrym volcano.

Moussallam Y, Rose-Koga EF, Koga KT, Médard E, Bani P, Devidal JL, Tari D (2019) Fast ascent rate during the 2017-2018 Plinian eruption of Ambae (Aoba) volcano; a petrological investigation. Contribution to Mineralogy and Petrology 174: 90, doi: 10.1007/s00410-019-1625-z.

PETITE TERRE RECENT VOLCANISM

I have recalibrated an accurate Al-in hornblende barometer from experimental litterature data on rhyolites (Médard and Le Pennec, submitted). This new barometer takes into account the effect of both edenite and Tschermack substitutions on Al concentrations. Existing litterature data show a very good pressure-dependence of the Tschermack substitution (correlation coefficient of 0.95) for amphibole in equilibrium with biotite, plagioclase and quartz. Our new barometer reproduces experimental pressures with an average error of 58 MPa (equivalent to a depth of 2.2 km) in the 100-400 MPa range. More experiments are underway to improve the barometer’s accuracy. Compared to previous barometers, this new calibration is independent of temperature, and gives a much better resolution for magma chamber depth.

Collaborators: Carole Berthod, Lucia Gurioli, Patrick Bachèlery, Andrea Di Muro

Berthod C, Médard E, Bachèlery P, Gurioli L, Di Muro A, Peltier A, Komorowski JC, Benbakkar M, Devidal JL, Langlade J, Besson P, Boudon G, Rose-Koga E, Deplus C, Le Friant A, Bickert M, Nowak S, Thinon I, Burckel P, Hidalgo S, Kaliwoda M, Jorry S, Fouquet Y, Feuillet N (submitted) The 2018-ongoing Mayotte submarine eruption: magma migration imaged by petrological monitoring.

MAYOTTE SUBMARINE EASTERN VOLCANIC CHAIN

I have recalibrated an accurate Al-in hornblende barometer from experimental litterature data on rhyolites (Médard and Le Pennec, submitted). This new barometer takes into account the effect of both edenite and Tschermack substitutions on Al concentrations. Existing litterature data show a very good pressure-dependence of the Tschermack substitution (correlation coefficient of 0.95) for amphibole in equilibrium with biotite, plagioclase and quartz. Our new barometer reproduces experimental pressures with an average error of 58 MPa (equivalent to a depth of 2.2 km) in the 100-400 MPa range. More experiments are underway to improve the barometer’s accuracy. Compared to previous barometers, this new calibration is independent of temperature, and gives a much better resolution for magma chamber depth.

We have been performing detailed thermometric studies on basaltic lava channels at Kilauea (Hawaii) and Piton de la Fournaise (Reunion Island, Indian Ocean). With careful sampling and sample preparation, the olivine/liquid thermometer of Ford (1983) gives enough precision to be able to calculate cooling rates in lava channels. Values of about 7 °C/km have been determined for the Muliwai a Pele lava channel emplaced during the final stage of Mauna Ulu’s 1969–1974 eruption. These values are then integrated into multiparameters models of lava flows that can be then used for prediction of lava flow paths.

Collaborators: Lucia Gurioli, Andrea Di Muro

We have been performing detailed thermometric studies on XXth century basaltic lava channels at Kilauea (Hawaii) and Piton de la Fournaise (Reunion Island, Indian Ocean). With careful sampling and sample preparation, the olivine/liquid thermometer of Ford (1983) gives enough precision to be able to calculate cooling rates in lava channels. Values of about 7 °C/km have been determined for the Muliwai a Pele lava channel emplaced during the final stage of Mauna Ulu’s 1969–1974 eruption. These values are then integrated into multiparameters models of lava flows that can be then used for prediction of lava flow paths.

publications

Berthod C, Médard E, Bachèlery P, Gurioli L, Di Muro A, Peltier A, Komorowski JC, Benbakkar M, Devidal JL, Langlade J, Besson P, Boudon G, Rose-Koga E, Deplus C, Le Friant A, Bickert M, Nowak S, Thinon I, Burckel P, Hidalgo S, Kaliwoda M, Jorry S, Fouquet Y, Feuillet N (2021) The 2018-ongoing Mayotte submarine eruption: magma migration imaged by petrological monitoring. Earth and Planetary Science Letters 571: 117085, doi: 10.1016/j.epsl.2021.117085

Berthod C, Médard E, Di Muro A, Hassen-Ali T, Gurioli L, Chauvel C, Komorowski JC, Bachèlery P, Peltier A, Benbakkar M, Devidal JL, Besson P, Deplus C, Nowak S, Thinon I, Burckel P, Hidalgo S, Feuillet N, Jorry S, Fouquet Y (2021) Mantle xenolith-bearing phonolites and basanites feed the active volcanic ridge of Mayotte (Comoros archipelago, Mozambique Channel). Contribution to Mineralogy and Petrology 176: 75, doi: 0.1007/s00410-021-01833-1

Berthod C, Komorowski J-C, Gurioli L, Médard E, Bachèlery P, Besson P, Verdurme P, Chevrel O, Di Muro A, Peltier A, Devidal J-L, Nowak S, Thinon I, Burckel P, Hidalgo S, Deplus C, Loubrieu B, Pierre D, Bermell S, Pitel-Roudault M, Réaud Y, Fouchard S, Bickert M, Le Friant A, Paquet F, Feuillet N, Jorry S, Fouquet Y, Rinnert E, Cathalot C, Lebas E (2022) Temporal evolution of the 2018-2021 Fani Maoré submarine eruption 50 km east of Mayotte revealed by in-situ submarine sampling and petrological monitoring. Comptes Rendus Geosciences, doi : 10.5802/crgeos.155

Verdurme P, Le Losq C, Chevrel O, Pannefieu S, Médard E, Berthod C, Komorowski J-C, Bachèlery P, Neuville DR, Gurioli L (2023) Viscosity of crystal-free silicate melts from the active submarine volcanic chain of Mayotte. Chemical Geology, in revision