Continental Magmatism and Asymmetry in the South Atlantic

Melt production rates are estimated for the ocean tracks (Rio Grande Rise, Walvis-Ridge) and the onshore Parana/Etendeka Flood Basalts for the mantle plume currently associated with Tristan da Cunha. There is a marked asymmetry in the melt production rates in both .oceanic and continental areas, and those in the Parana may have been 5-10 times greater than those on the Rio Grande Rise. Melt production rates reflect the presence of volatiles in the sub-continental mantle, and differences in the tectonic regimes on either side of the South Atlantic.