Petrogenesis of the volcanic suite of Bouvet ya (Bouvet Island), South Atlantic

Whole rock and mineral compositions of volcanic rocks collected during the Norwegian Polarsirkel expedition (1978/79) to the volcanic island of Bovetøya (close to the Bouvet Triple Junction) are discussed and compared with previously published data from the island. The rock types, hawaiite, benmoreite, and peralkaline trachyte and rhyolite (comendite) are related to each other by crystal fractionation processes. The trace element and radiogenic isotope signatures displayed by the Bouvetøya rocks are those of a moderately enriched oceanic island suite. On several isotope plots Bouvetøya rocks fall on or close to mixing lines between the enriched EM-1 and HIMU mantle components. Mixing between depleted morb mantle (DMM) and enriched components is not likely. Thus, Bouvetøya displays a typical plume signature.