title: The initiation of segmented buoyancy-driven melting during continental breakup.
abstract: Melting of the mantle during continental breakup leads to magmatic intrusion and volcanism, yet our understanding of the location and dominant mechanisms of melt generation in rifting environments is impeded by a paucity of direct observations of mantle melting. It is unclear when during the rifting process the segmented nature of magma supply typical of seafloor spreading initiates. Here, we use Rayleigh-wave tomography to construct a high-resolution absolute three-dimensional shear-wave velocity model of the upper 250 km beneath the Afar triple junction, imaging the mantle response during progressive continental breakup. Our model suggests melt production is highest and melting depths deepest early during continental breakup. Elevated melt production during continental rifting is likely due to localized thinning and melt focusing when the rift is narrow. In addition, we interpret segmented zones of melt supply beneath the rift, suggesting that buoyancy-driven active upwelling of the mantle initiates early during continental rifting.
authors.affiliation: Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, UK.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Gallacher
authors.affiliation: Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, UK.|Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Florence 50121, Italy.
authors.forename: Derek
authors.initials: D
authors.lastname: Keir
authors.affiliation: Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, UK.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Harmon
authors.affiliation: School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Graham
authors.initials: G
authors.lastname: Stuart
authors.affiliation: Sorbonne Universités, UPMC - ISTEP - CNRS UMR7193, Paris 75252, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Leroy
authors.affiliation: Department of Earth and Planetary Sciences, Birkbeck, University of London, London WC1E 7HX, UK.
authors.forename: James O S
authors.initials: JO
authors.lastname: Hammond
authors.affiliation: School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK.
authors.forename: J-Michael
authors.initials: JM
authors.lastname: Kendall
authors.affiliation: Institute of Geophysics, Space and Astronomy, Addis Ababa University, Addis Ababa, Ethiopia.
authors.forename: Atalay
authors.initials: A
authors.lastname: Ayele
authors.affiliation: School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK.
authors.forename: Berhe
authors.initials: B
authors.lastname: Goitom
authors.affiliation: Eritrea Institute of Technology, Asmara, Eritrea.
authors.forename: Ghebrebrhan
authors.initials: G
authors.lastname: Ogubazghi
authors.affiliation: Sorbonne Universités, UPMC - ISTEP - CNRS UMR7193, Paris 75252, France.|Seismological and Volcanological Observatory Center, Dhamar, Yemen.
authors.forename: Abdulhakim
authors.initials: A
authors.lastname: Ahmed