Thermal and Petrologic Structure of Subduction Zones

  1. Gray E. Bebout,
  2. David W. Scholl,
  3. Stephen H. Kirby and
  4. John P. Platt
  1. Simon M. Peacock

Published Online: 23 MAR 2013

DOI: 10.1029/GM096p0119

Subduction Top to Bottom

Subduction Top to Bottom

How to Cite

Peacock, S. M. (1996) Thermal and Petrologic Structure of Subduction Zones, in Subduction Top to Bottom (eds G. E. Bebout, D. W. Scholl, S. H. Kirby and J. P. Platt), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM096p0119

Author Information

  1. Department of Geology, Arizona State University, Tempe, Arizona

Publication History

  1. Published Online: 23 MAR 2013
  2. Published Print: 1 JAN 1996

ISBN Information

Print ISBN: 9780875900780

Online ISBN: 9781118664575



  • Subduction zones


The subduction of oceanic lithosphere depresses isotherms on a regional scale resulting in large thermal anomalies in the upper mantle. The thermal structure of a subduction zone depends on many parameters including the thermal structure (age) of the incoming lithosphere, convergence rate, geometry of subduction, radioactive heating, induced convection in the overlying mantle wedge, and rate of shear heating along the subduction shear zone. Numerical calculations suggest that subduction shear-zone temperatures beneath the volcanic front generally lie between 500 and 700°C, but considerable uncertainty in the thermal structure of subduction zones results from uncertainties in the rate of shear heating and mantle-wedge convection. Low forearc heat flow (25–50 mW/m2), seismic coupling to depths of ∼40 km, and high-pressure, low-temperature metamorphic rocks all indicate that subduction zones are cool and constrain subduction zone shear stresses in the brittle (frictional) regime to 10–30 MPa or 1–5% of lithostatic pressure. In most subduction zones, the subducting oceanic crust passes through the blueschist[RIGHTWARDS ARROW]eclogite metamorphic facies transition where continuous dehydration reactions may release large amounts of H2O. Integrated over time, aqueous fluids released from the subducting slab cause extensive hydration of the overlying mantle wedge and trigger partial melting in the core of the convecting mantle wedge. Partial melting of subducting oceanic crust occurs only under rare circumstances such as near the subduction of a spreading ridge. Uncertainties in the petrologic structure of subduction zones result from uncertainties in the thermal structure, the distribution of hydrous minerals in the oceanic lithosphere, and possible kinetic barriers to metamorphic reactions. Detailed seismological investigations that illuminate the velocity and attenuation structure of the subducting slab and mantle wedge have the potential to better define the thermal and petrologic structure of subduction zones.