A simple three-dimensional model of thermo–chemical convection in the mantle wedge

Future directions in subduction modeling

“…(viii) Suppression of 3D thermal instabilities in the mantle wedge by low density chemical anomalies originating from downgoing slabs slab (e.g., due to hydration) and instead stabilization of thermal-chemical plumes and/or an internally convecting chemically buoyant "cold nose" (Fig. 9b, right) in the upper corner of the mantle wedge (Honda et al, 2010). Richard and Bercovici (2009) have recently investigated the consequences of deep dehydration of subducted slabs for mantle convection based on 2D thermo-mechanical models including water diffusion (Fig.…”

“…Honda and Saito (2003) developed the first simple 3D regional subduction model, where a kinematically prescribed inclined slab was used to study mantle wedge dynamics. This approach has been used by a number of additional studies to investigate 3D thermal, compositional and flow structures around descending slabs (e.g., Honda and Yoshida, 2005;Honda, 2009;Honda et al, 2010). Zhu et al (2009Zhu et al ( , 2011 also developed complex thermal-chemical-mineralogical regional 3D subduction models with a free-surface, high-resolution mesh and spontaneously bending slabs (Zhu et al, 2009(Zhu et al, , 2011.…”

“…Further investigations of thermal-chemical, mantle wedge convection will likely involve broadening the 3D modeling approaches and theoretical understanding of the variability of modeled plume morphologies in the mantle wedge (e.g., Zhu et al, 2009Zhu et al, , 2011Honda et al, 2010). Further progress in understanding the relative significance of thermal and chemical components of mantle wedge convection will likely require the implementation of more sophisticated fluid and melt transport algorithms (e.g., Iwamori, 1998Iwamori, , 2007Connolly and Podladchikov, 1998;Rozhko et al, 2007) that may help to better quantifying the actual magnitude of chemical buoyancy present above slabs in nature.…”

“…(a) Model byZhu et al (2009), the 1077 • C isosurface of temperature (yellow) with partially molten hydrated rocks (red), which are responsible for plume buoyancy, note two trench-parallel lines of plumes that develop from the slab at different depths. (b) Model byHonda et al (2010), finger-like (left) and sheet-like (right) patterns of convection in the mantle wedge depending on the chemical/thermal buoyancy ratio (R ), the 1000 • C isosurface of temperature (yellow) is shown).…”

Melt evolution above a spontaneously retreating subducting slab in a three-dimensional model

“…Zhu et al (2009) showed threedimensional (3-D) complex thermochemical plumes and their corresponding integrated melt productivities at the modeled surface. Honda et al (2010) used 3-D simple models to analyze the influence of water on the mantle flow. However, there is no knowledge about melt distribution inside 3-D natural subduction zone.…”