Geochemical and SrNdHfO isotopic constraints on volcanic petrogenesis at the Sunda arc
Heather Handley, completed PhD
The Sunda island arc of Indonesia formed as a result of the northward subduction of the IndoAustralian Plate beneath the Eurasian Plate. Alongarc variations in the composition and thickness of the overriding Eurasian plate and variation in the type and amount of sediment deposited on the subducting plate create differential effects on Sunda arc lava geochemistry. Detailed study of volcanic rocks from Salak, Gede Volcanic Complex (GVC) in West Java and Ijen Volcanic Complex (IVC) in East Java was carried out in order to establish the relative importance and contributions of various potential source components and compositionmodifying processes at individual volcanic centres, prior to investigating petrogenetic variation along the arc.
Differentiation processes play a major role in modifying the geochemical composition of Sunda arc magmas. However, the relative importance and traceable impact of the different processes varies at each volcanic centre. Fractional crystallisation of a typical Javan island arc mineral assemblage exerts the largest control on major and trace element composition of the volcanic rocks.