Magmatic evolution of island arc and backarc crust and implications for hydrothermal venting in the NE Tonga arc

Third Party Funds Group - Sub project

Overall project details

Overall project: TONGARIFT

Project Details

Project leader:
Prof. Dr. Karsten Haase

Project members:
PD Dr. Christoph Beier
Dr. Stefan Krumm
PD Dr. Marcel Regelous

Contributing FAU Organisations:
Geozentrum Nordbayern
Lehrstuhl für Endogene Geodynamik

Funding source: Bundesministerium für Bildung und Forschung (BMBF)
Start date: 01/02/2018
End date: 31/03/2020

Abstract (technical / expert description):

Oceanic island arcs probably evolve through different tectonic stages that are marked by the formation and eruption of different magmatic rocks. Boninites have a peculiar geochemical composition reflecting partial melting of highly depleted mantle and are believed to be typical for the early stages of island arc evolution. The main objectives of the proposed project are sampling of shallow crustal profiles at the NE Tonga Ridge and Lau backarc basin where boninitic lavas appear to be very abundant in order to establish the stratigraphic situation of these boninites. Lavas from the N Tonga volcanic islands have unique compositions reflecting very strong depletion of the mantle wedge and re-enrichment by fluids from subducted seamount lavas, whereas some backarc lavas indicate influence of mantle plume material, possibly from Samoa. The Niuatahi volcano is surrounded by young lava flows and volcanic ridges that reach to the NE Lau spreading centre and the abundant on- and off-axis lavas allow studying the magma generation and mixing processes from the arc front to the backarc. We propose to study the composition of the NE Tonga volcanoes to better define the different sources and the implications for mantle and melting dynamics in a subduction zone. The recently active volcanoes in the NE Lau backarc and NE Tonga arc show highly variable hydrothermal venting and thus offer a natural laboratory for the study of the effects of magma degassing on hydrothermal fluid and precipitate composition. We suggest sampling of different vents related to different magmatic structures in order to test models of the effects of varying magmatic volatile input and water depth on the fluids.

External Partners

Universität Bremen
Jacobs University Bremen gGmbH

Last updated on 2018-22-11 at 16:47