Imaging the lithospheric structure and plumbing system below the Mayotte volcanic zone

• Published in: Comptes rendus. Geoscience Vol. 354; no. S2; pp. 47 - 64
• Main Authors: Dofal, Anthony, Michon, Laurent, Fontaine, Fabrice R., Rindraharisaona, Elisa, Barruol, Guilhem, Tkalčić, Hrvoje
• Format: Journal Article
• Language: English
• Published: Paris Académie des Sciences. Institut de France 2022; Académie des sciences (Paris); Académie des sciences
• Subjects: Cenozoic; Comoros archipelago; Earth Sciences; Geophysics; Joint inversion; Lithosphere; Magma; Magmatic plumbing system; Mayotte; Receiver function; Reservoirs; Rheological controls; Rheology; Sciences of the Universe; Velocity; Volcanic eruptions; Volcanoes; Wave velocity; Receiver function; Lithosphere; Mayotte; Comoros archipelago; Magmatic plumbing system; Joint inversion; Rheological controls
• ISSN: 1778-7025; 1631-0713; 1778-7025
• DOI: 10.5802/crgeos.190

Teleseismic receiver-functions and Rayleigh-wave dispersion curves are jointly inverted for quantifying \(S\)-wave velocity profiles beneath the active volcanic zone off Mayotte. We show that the lithosphere in the east-northeast quadrant is composed of four main layers, interpreted as the volcanic edifice, the crust with underplating, the lithospheric mantle, and the asthenosphere, the latter two presenting a main low-velocity zone. The depths of the old (10–11 km) and new Moho (28–31 km) coincide with the two magma reservoirs evidenced by recent seismological and petrological methods. We propose that the main magma reservoir composed of mush with an increasing amount of liquid extends down to 54 km depth. This magma storage develops from a rheological contrast between the ductile lower and brittle upper lithospheric mantle and accounts for most of the volcanic eruption-related seismicity. Finally, the abnormally small thickness of the lithospheric mantle (33 km) is likely a result of a thermal thinning since the onset of Cenozoic magmatism.