Contrasting geophysical and geochemical signatures of a volcano at the axis of the Wharton Fossil Ridge (N-E Indian Ocean)

Hélène Hébert (1) , Benoit Villemant (2, 1) , Christine Deplus (1) , Michel Diament (1)

1 Laboratoire de Gravimétrie et Géodynamique, UMR 7577
2 iSTeP - Institut des Sciences de la Terre de Paris

The Styx volcano is a prominent seamount (20-30 km diameter, 2500 m high) located at the axis of the Wharton fossil spreading center (N-E Indian Ocean), where seafloor spreading stopped 40 Ma ago. Gravity modeling shows that it was emplaced on a weak lithosphere, in agreement with an on axis origin when seafloor spreading was active. The rocks dredged at the summit of the volcano are extreme typical alkaline basalts, indicating a deep enriched mantle source. We show here that most of this seamount was emplaced during the final stage of the seafloor spreading in the Wharton Basin. We then discuss how alkaline magmatism can be emplaced at the summit of the Styx.

Domaines: Sciences de la Terre

Hélène Hébert, Benoit Villemant, Christine Deplus, Michel Diament. Contrasting geophysical and geochemical signatures of a volcano at the axis of the Wharton Fossil Ridge (N-E Indian Ocean). Geophysical Research Letters, 1999, 26 (8), pp.1053-1056. ⟨10.1029/1999GL900160⟩. ⟨insu-01354338⟩