SO232 – The Mozambique Ridge: a document of massive multistage magmatism
The Mozambique Ridge, a prominent basement high in the southwestern Indian Ocean, consists of four major geomorphological segments associated with numerous phases of volcanic activity in the Lower Cretaceous (König and Jokat, 2010). The nature and origin of the Mozambique Ridge have been intensely debated with one hypothesis suggesting a Large Igneous Province origin (Gohl et al., 2011). High-resolution seismic reflection data gathered during Sonne expedition SO232 reveal a large number of extrusion centres with a random distribution throughout the southern Mozambique Ridge and the nearby Transkei Rise. Intrabasement reflections emerge from the extrusion centres and are interpreted to represent massive lava flow sequences. Such lava flow sequences are characteristic for eruptions leading to the formation of continental and oceanic flood basalt provinces, hence supporting a Large Igneous Province origin of the Mozambique Ridge (Uenzelmann-Neben et al., 1999; Sager et al., 2013; Pietsch and Uenzelmann-Neben, 2015). We observe evidence for widespread post-sedimentary magmatic activity that we suggest to correlate with a Neogene southward propagation of the East African Rift System. Based on our volumetric analysis of the southern Mozambique Ridge we infer a rapid sequential emplacement between ~131 and ~125 Ma, which is similar to the short formation periods of other Large Igneous Provinces like the Agulhas Plateau.