Geochemical and iron isotopic study of iron deposits at Mayotte submarine volcanic system…and first vanadium isotopic measurements

Since 2018, a new volcanic edifice, Fani Maore, has grown on the volcanic ridge located on the eastern submarine flank of Mayotte (Comoros archipelago, Indian Ocean). Fani Maore lies at 3500m deep, is 820m high and is located 50km east of Mayotte. This event led to lava flows emplacements on its flanks as well as deposits of tephra and iron oxides in the surrounding sediments. This eruption is the largest submarine event ever documented and offers a unique opportunity to better understand the iron biogeochemical cycle in the deep ocean just after the emplacement of a such extreme event. To tackle these questions, the multidisciplinary GEOFLAMME cruise (10.17600/18001297) conducted in May 2021on board the R/V Pourquoi Pas? allowed us to sample water particles, Fe-rich deposits and sediment cores along several eastward transects from the Fani Maore edifice towards the open Indian Ocean. This seminar will present the geochemical and iron isotopic data that have enabled an understanding of the origin and processes associated with these major iron deposits on sediments.