Abstracts Earth and Environmental Sciences

Magma genesis and slab-wedge interaction across an island arc-continent collision zone, East Sunda Arc, Indonesia

by J.A. Hoogewerff

This thesis presents the results of a detailed trace element and isotope geochemistry study into the magma-genesis ofvolcanoes in the Adonara-Pantar Section (APS) ofthe East Sunda Arc in Indonesia, a setting where an oceanic island arc is colliding with a passive continental margin. Sr, Nd, Pb, Ra, Th and U isotopes were analysed together with major and trace elements from five active and more than ten inactive volcanic centres on seven islands ofthe APS. In order to characterise the input into the subduction zone, literature data and additional analyses on samples of marine sediments from locations in front ofthe Timor Trough (Vroon, 1982; Vroon et aI., 1995) were used. The results of this study (1) identify different mantle and subduction-related components that contribute to the magma source region in the sub-arc mantle ofthe APS, (2) provide constraints for the mode of material transfer between the subducted slab and these magma sources, and (3) provide insight into spatial changes of this process as a function ofthe depth ofthe Benioff-Zone.