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   The thermal structure of subduction zones provides important insight into the thermal and chemical exchange between subducted oceanic lithosphere and overlying mantle wedge and into magma generation and transport. Various thermal models have been developed based on analytical approximations (Molnar and England, 1990, 1995; Davies, 1999), analytical solutions for wedge corner flow (Peacock, 1990a,b, 1991, 1996, 2003; Peacock and Hyndman, 1999; Peacock and Wang, 1999; Billen and Gurnis, 2001), and more recently, temperature- and stress-dependent viscosity (von Hunen et al., 2000; van Keken et al., 2002; Gerya and Yuen, 2003).
   Dehydration of subducting lithosphere likely trasports fluids into the mantle wedge where the viscosity is decreased. Such a decrease in viscosity could form a low viscosity wedge or a low viscosity channel on top of the subducting slab. Using numerical models, we investigate the influence of low viscosity wedges and channels on subduction zone structure (Manea and Gurnis, 2007).

References

♦Billen, M.I., and Gurnis, M., 2001. A low viscosity wedge in subduction zones. Earth and Planetary Science Letters, v. 193, no. 1-2, pp.227-236.
♦Davies, J.H., 1999. The role of hydraulic fractures and intermediate-depth earthquakes in generating subduction-zone magmatism. Nature, v.398, p.142-145.
♦ Gerya, T.V., and Yuen, D.A., 2003. Rayleigh-Taylor instabilities from hydration and melting propel "cold plumes" at subduction zones. Earth and Planetary Science Letters, v.212, pp.47-62.
♦ Manea, V.C., and Gurnis, M., 2007. Subduction zone evolution and low viscosity wedges and channels. Under review, Earth and Planetary Science Letters. Molnar, P., and England, P., 1990. Temperatures, heat flux, and frictional stress near major thrust faults. Journal of Geophysical Research, v.95, pp.4833-4856.
♦ Molnar, P., and England, P., 1995. Temperatures in zones of steady state underthrusting of young oceanic lithosphere. Earth and Planetary Science Letters, v.131, pp.57-70.
♦ Peacock, S.M., 1990a. Fluid processes in subduction zone. Science. v. 248, no.4953, pp.329-337.
♦ Peacock, S.M., 1990b. Numerical simulation of metamorphic pressure-time paths and fluid production in subducting slabs. Tectonics, v.9, no.5, pp.1197-1211.
♦ Peacock, S.M., 1991. Numerical simulation of subduction zone pressure-temperature-time paths: Constraints on fluid production and arc magmatism, in Tarney, J., et al., eds., The behaviour and influence of fluids in subduction zones. Philosophical Transactions of the Royal Society of London, A335, pp.341-353.
♦ Peacock, S.M., 1996. Thermal and petrologic structure of subduction zones, in Bebout, G.E., et al., eds., Subduction zones, top to bottom. Washington, D.C., American Geohysical Union, Geophysical Monograph 96, pp.119-133.
♦ Peacock, S.M., 2003. Thermal structure and metamorphic evolution of subducting slabs, in Eiler, J., ed., Inside the subduction factory. Washington, D.C., American Geohysical Union, Geophysical Monograph 138, pp.7-22.
♦ Peacock, S.M., and Hyndman, R.D., 1999. Hydrous minerals in the mantle wedge and the maximum depth of subduction thrust earthquakes. Geophysical Research Letters, v.26, pp.2517-2520.
♦ Peacock, S.M., and Wang, K., 1999. Seismic consequences of warm versus cool subdcution metamorphism: Examples from southwest and northeast Japan. Science, v.286, pp.937-939.
♦ van Keken, P.E.,Kiefer, B., and Peacock, S.M., 2002. High resolution models of subduction zones: Implications for mineral dehydration reactions and transport of water into deep mantle. Geochemistry, Geophysics, Geosystems, v.3, no.10, p.20.
♦ von Hunen, J., van den Berg, A.P., and Vlaar, N.J., 2000. A thermo-mechanical model of horizontal subduction below an overriding plate. Earth and Planetary Science Letters, v.182, p.157-169.