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High-resolution 3D geochemical-petrological-thermomechanical modelling of subduction and magmatic arcs development

English title High-resolution 3D geochemical-petrological-thermomechanical modelling of subduction and magmatic arcs development
Applicant Tackley Paul
Number 126832
Funding scheme Project funding
Research institution Institut für Geophysik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geophysics
Start/End 01.10.2009 - 30.09.2011
Approved amount 225'647.00
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Keywords (12)

Mantle convection; Subduction; Geochemistry; melting; melt migration; magma transport; back-arc volcanism; dehydration; volcanic arcs; numerical modelling; mantle wedge; slab dehydration

Lay Summary (English)

Lead
Lay summary
Subduction zones are the places where oceanic plates enter the Earth's interior and sink downwards, and the regions above the subducting plates (slabs) are the locations of complex melting-fluid-petrological processes. Seismic studies of the mantle above subduction zones and the spatial and temporal variability of volcanism in related magmatic arcs indicate that Earth's uppermost mantle above slabs (i.e. in so called mantle wedges) has a complex 3D structure. This structure is mainly related to intense hydration and melting processes triggered by slab dewatering. However, published 3D models of subduction are rather simplified and performed for relatively large scales and at relatively coarse resolution which does not allow capturing the complexity of mantle wedge structures in nature. Also, no hydration, melting and dewatering processes associated with subduction have yet been implemented in 3D, which precludes relating mantle wedge processes to the spatial variations in volcanic activity at the surface. In this project we are performing high-resolution 3D modelling of subduction using our recent 3D advanced numerical geodynamic modeling codes. The main objective of this project is to achieve a better understanding of processes controlling (1) 3D thermal and chemical mantle wedge dynamics (2) the formation of isolated magmatic activity centers in magmatic arcs. We are modeling in 3D hydration, melting and dewatering dynamics during subduction and analyze different subduction scenarios such as retreating/advancing intra-oceanic and oceanic-continental subduction. In cooperation with other research groups we will also perform comparison and testing of our numerical simulations at the subduction zone scale to natural data on magmatic activity distribution in subduction zones and seismic structure of mantle wedges.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Influences of the buoyancy of partially molten rock on 3-D plume patterns and melt productivity above retreating slabs
Zhu GZ, Gerya TV, Honda S, Tackley PJ, Yuen DA (2011), Influences of the buoyancy of partially molten rock on 3-D plume patterns and melt productivity above retreating slabs, in PHYSICS OF THE EARTH AND PLANETARY INTERIORS, 185(3-4), 112-121.
Melt evolution above a spontaneously retreating subducting slab in a three-dimensional model
Zhu GZ, Gerya T, Yuen DA (2011), Melt evolution above a spontaneously retreating subducting slab in a three-dimensional model, in JOURNAL OF EARTH SCIENCE, 22(2), 137-142.
A simple three-dimensional model of thermo-chemical convection in the mantle wedge
Honda S, Gerya T, Zhu GZ (2010), A simple three-dimensional model of thermo-chemical convection in the mantle wedge, in EARTH AND PLANETARY SCIENCE LETTERS, 290(3-4), 311-318.
Subduction of the Western Pacific Plate underneath Northeast China: Implications of numerical studies
Zhu GZ, Shi YL, Tackley P (2010), Subduction of the Western Pacific Plate underneath Northeast China: Implications of numerical studies, in PHYSICS OF THE EARTH AND PLANETARY INTERIORS, 178(1-2), 92-99.
Three-dimensional dynamics of hydrous thermal-chemical plumes in oceanic subduction zones
Zhu GZ, Gerya TV, Yuen DA, Honda S, Yoshida T, Connolly JAD (2009), Three-dimensional dynamics of hydrous thermal-chemical plumes in oceanic subduction zones, in GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, 10, 1-1.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
11th International Workshop on Modelling of Mantle Convection & Lithospheric Dynamics 22.07.2011 Braunwald, Switzerland
Japan Geoscience Union 22.05.2011 Makuhari, Japan
EGU General Assembly 03.04.2011 Vienna
Western Pacific Geoscience Meeting 2010 22.06.2010 Taipei
European Geosciences Union General Assembly 2010 02.05.2010 Vienna
International Workshop on Geodynamical Phenomena: From Field, Observational, Computational, Seismological and Rheological Perspectives 19.08.2009 Suzdal, Russia
European Geoscience Union General Assembly 2009 19.04.2009 Vienna
American Geophysical Union Fall Meeting 2008 11.12.2008 San Francisco


Associated projects

Number Title Start Funding scheme
116381 Coupled chemical-thermal-mechanical modelling of magma generation and migration in subduction zones 01.04.2007 Project funding
113672 Coupled geochemical-petrological-geodynamical modelling of subduction zones and global mantle convection 01.12.2006 Project funding

Abstract

Thermomechanical structures and mantle flows above subducting slabs are likely to be inherently 3D, as indicated by seismic tomography of mantle wedges and spatial and temporal variability of arc volcanism. Numerical modelling of subduction zones and mantle wedges in 3D is a rapidly evolving topic, with significant progress during the last decade. However, published 3D models of subduction are rather simplified and performed for relatively large scales and at relatively low resolution which does not allow capturing the complexity of mantle wedge struc-tures in nature. Also, no hydration and melting processes associated with subduction (and modelled in 2D) have yet been implemented in 3D, which precludes relating mantle wedge processes to the spatial variations in volcanic activity at the surface. Here we propose to fill the gap in high-resolution 3D modelling of subduction using our recent 3D petrological-thermomechanical numerical geodynamic modeling codes. The main objective of this project is to achieve a better understanding of processes controlling (1) 3D thermal-chemical mantle wedge dynamics, which significantly affects the subduction process and (2) the formation of isolated magmatic activity centers in subduction-related magmatic arcs. Our 3D simulations will therefore account for: (i) mantle flow associated with the sponta-neously bending subducting plate, (ii) slab water release, (iii) slab fluid propagation that will trigger partial melting at the slab surface, (iv) melt ascent, (vi) variations in density and viscos-ity of both fluids and rocks as a function of local conditions and (v) relations between melting an melt transport dynamics in 3D and crustal growth (volcanic activity) at the surface. We will model and analyze different subduction scenarios such as retreating/advancing intra-oceanic and oceanic-continental subduction in term of thermal-chemical structures and melting pat-tern forming in the mantle wedge and resulting pattern of crustal growth (volcanic activity) forming at the surface. Of particular interest for our study is the relative efficiency of compet-ing porous and diapiric melt transport modes in the mantle wedge, which will strongly depend upon the relative rate of porous flow compared to the velocity of mechanical ascent of buoyant diapiric structures. In cooperation with other research groups we will also perform comparison and testing of our numerical simulations at the subduction zone scale to natural data on magmatic activity distribution in subduction zones and seismic structure of mantle wedges. We request funds for two years for one postdoc and research costs involved by his work. This project builds on a previous SNF-funded postdoc project.
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