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 compositio...

Fifteen andesite-dacite stratovolcanoes on the volcanic front of a single segment of the Andean arc show along-arc changes in isotopic and elemental ratios that demonstrate large crustal contributions to magma genesis. All 15 centers lie 90 km above the Benioff zone and 280 _+ 20 km from the trench axis. Rate and geometry of subduction and composition and age of subducted sediments and seafloor...