Testing a New Model for Initiation of Subduction in the Western Pacific: 3He/4He Analysis of Middle Eocene Boninites
PROJECT DETAILS ONLY - NO DATA. This proposal seeks to test the hypothesis that a mantle hotspot was responsible for generating boninite magmas in the Izu - Bonin - Mariana (IBM) arc during the middle Eocene. Reconstruction of the plate configuration at that time places the nascent IBM arc close to the location of the present Manus Basin, where a high 3He/4He hotspot has been identified through helium isotope data and tomographic imaging. This project will deliver: 3He/4He data for middle Eocene boninites to resolve the hotspot-present or hotspot-absent models for initiation of the IBM arc. Pb and O isotope ratios and U and Th concentration data to aid in constraining subduction and crustal contamination in the petrogenesis of these rocks. A framework for investigating Archean tectonics and volcanic massive sulphide deposits.