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