Mantle plume and rift-related volcanism during the evolution of the Rio Grande Rise

Abstract The Rio Grande Rise in the western South Atlantic Ocean has been interpreted as either an oceanic plateau related to Tristan-Gough mantle plume, or a fragment of detached continental crust. Here we present new major and trace element data for volcanic rocks from eastern adjacent Jean Charcot Seamount Chain. older parts are comprised tholeiitic basalt with moderately enriched compositions likely formed above plume close southern Mid-Atlantic Ridge. Younger alkalic lavas Chain were by lower degrees melting beneath thicker lithosphere intraplate setting possibly during rifting plateau. There is no clear geochemical evidence that remnants crust Rise.