Tectonic setting of Mayor Island volcano (Note)

Abstract

Mayor Island, a peralkaline volcano in the northwestern Bay of Plenty, is chemically different from all other Cenozoic lavas in the North Island. It is of similar pantelleritic composition to the islands of Pantelleria and Socorro and the silicic volcanoes of the Main Ethiopian Rift, each of which is associated with a tensional environment. Mayor Island is near the edge of the continental shelf, within a southeastwards extension of the Ngatoro Basin, a steep sided graben structure which is regarded as an extensional island-arc basin. The tectonic setting of the island is thus comparable to the other known pantelleritic volcanoes.