Heat flow measurements in the Northern Mozambique Channel

Abstract

Heat flow in the Northern Mozambique Channel is poorly constrained, with only a few old measurements indicating relatively low values of 55-62 mW/m 2 . During the SISMAORE cruise to the Northern Mozambique Channel, we obtained new heat flow measurements at four sites, using sediment corers equipped with thermal probes. Three of the sites yield values of 42-47 mW/m 2 , confirming low regional heat flow in this area. Our values are consistent with a Jurassic oceanic lithosphere around Mayotte, although the presence of very thin continental crust or continental fragments could also explain the observed heat flow. Our values do not support a regional thermal anomaly and so do not favor a hotspot model for Mayotte. However, at a fourth site located 30 km east of the submarine volcano that appeared in 2018 east of Mayotte, we measured a very high heat flow value of 235 mW/m 2 , which we relate to the circulation of hot fluids linked to recent magmatic activity.Résumé. Le flux de chaleur dans le nord du canal du Mozambique, basé sur des mesures anciennes et peu nombreuses, est faible (55-62 mW/m 2 ). Durant la campagne à la mer SISMAORE, nous avons obtenu quatre nouvelles mesures de flux de chaleur. Nos mesures donnent des valeurs de 47, 45 et 42 mW/m 2 qui confirment un flux de chaleur régional faible. Ces valeurs sont cohérentes avec une lithosphère océanique d'âge Jurassique autour de Mayotte, mais elles peuvent aussi être expliquées par une croûte continentale amincie, ou des enclaves de croûte continentale dans une croûte océanique. Nos faibles valeurs de flux ne sont pas en faveur d'une anomalie thermique régionale ni du modèle point chaud pour expliquer le volcanisme de Mayotte. Cependant, nous avons une mesure de flux,

Relative Sea Level and Coastal Vertical Movements in Relation to Volcano-Tectonic Processes at Mayotte Island, Indian Ocean

“…Potentially, this mantle/asthenospheric flow might be a pulse from either a complex hotspot system or a tectono-volcanic system with a deep root in the extension of the East African Rift, at the boundary of the Somali and Lwandle plates (Figure 8). An incipient plate boundary or a mantle heterogeneity could have triggered the volcano-tectonic evolution [109] and caused a complex volcano-tectonic cycle.…”

Volcano-tectonic structures of Mayotte’s upper submarine slope: insights from high-resolution bathymetry and in-situ imagery from a deep-towed camera

“…This region was affected by an episode of NW-SE rifting through the Permo-Triassic which was associated with the fragmentation of Gondwana [∼170-185 Ma, Eagles and König, 2008, Gaina et al, 2015, Leinweber and Jokat, 2012, Mueller and Jokat, 2019, Senkans et al, 2019, opening the Mozambique, Comores and Somali basins, during which Madagascar drifted southward [Mahanjane, 2012, Davis et al, 2016. The nature of the lithosphere (continental vs. oceanic) underlying the Comoros archipelago continues to be debated and has been diversely interpreted over the years [Nougier et al, 1986, Michon, 2016, Masquelet et al, 2022, Rolandone et al, 2022. The origin of volcanism in the area is also poorly understood, and proposed hypotheses include: (a) hot spot activity [Emerick and Duncan, 1982], (b) lithospheric fracture zones facilitating melt transport [Nougier et al, 1986], or (c) coupling of both processes, with the interaction of extensional tectonics and deeper astenospheric processes [e.g., Courgeon et al, 2018, Deville et al, 2018, Famin et al, 2020, Franke et al, 2015, Kusky et al, 2010, Michon, 2016, O'Connor et al, 2019, Wiles et al, 2020.…”

Pliocene-to-Holocene volcano-tectonic activity on Mohéli Island (Comoros archipelago) constrained by new K Ar ages

“…The Comoros archipelago is considered to be built on an oceanic lithosphere (e.g. Phethean et al, 2016;Rolandone et al, 2022;Masquelet et al, 2022), although there is debate about the possible existence of a continental remnant of Madagascar's drift underneath Mayotte (Dofal et al, 2022). According to trace element compositions and Sr-Nd-Pb isotopic ratios, the magmas of Mohéli, Anjouan, and Mayotte may be explained by mixing of a high µ = 238 U/ 204 Pb (HIMU) component and a depleted MORB-mantle (DMM) component at variable degrees of partial melting (Späth et al, 1996;Pelleter et al, 2014;Bachèlery and Hémond, 2016).…”