Two types of gabbroic xenoliths from Niijima volcano, Izu-Bonin arc: petrological and geochemical constraints

Abstract

Basaltic to rhyolitic magmas in a subduction zone setting contain many types of plutonic xenoliths. Niijima volcano is predominantly composed of rhyolitic lava domes and pyroclastic units with minor basaltic to andesitic volcanic units. In this study, we conducted petrographical and geochemical studies on the gabbroic xenoliths contained within the volcanic rocks from the northern part of the volcano. We determined the mineral chemistry, whole-rock major and trace element and isotopic compositions of plutonic xenoliths from Niijima volcano in order to clarify their origin and formation process.