Helium isotopes at Rungwe Volcanic Province, Tanzania, and the origin of East African Plateaux

[1] We report helium isotope ratios (He/He) of lavas and tephra of the Rungwe Volcanic Province (RVP) in southern Tanzania. Values as high as 15RA (RA = air He/He) far exceed typical upper mantle values, and are the first observation of plume‐like ratios south of the Turkana Depression which separates the topographic highs of the Ethiopia and Kenya domes. The African Superplume ‐ a tilted low‐velocity seismic anomaly extending to the core‐mantle boundary beneath southern Africa – is the likely source of these high He/He ratios. High He/He ratios at RVP together with similarly‐high values along the Main Ethiopian Rift and in Afar provide compelling evidence that the African Superplume is a feature that extends through the 670‐km seismic discontinuity and provides dynamic support – either as a single plume or via multiple upwellings – for the two main topographic features of the East Africa Rift System as well as heat and mass to drive continuing rift‐related magmatism. Citation: Hilton, D. R., S. A. Halldórsson, P. H. Barry, T. P. Fischer, J. M. de Moor, C. J. Ramirez, F. Mangasini, and P. Scarsi (2011), Helium isotopes at Rungwe Volcanic Province, Tanzania, and the origin of East African Plateaux, Geophys. Res. Lett., 38, L21304, doi:10.1029/2011GL049589.