Implications of slab mineralogy for subduction dynamics

• Published in: Physics of the earth and planetary interiors Vol. 127; no. 1; pp. 51 - 66
• Main Authors: Bina, Craig R., Stein, Seth, Marton, Frederic C., Van Ark, Emily M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2001
• Subjects: Morphology; Slab mineralogy; Subduction; Slab mineralogy; Morphology; Subduction
• ISSN: 0031-9201; 1872-7395
• DOI: 10.1016/S0031-9201(01)00221-7

Phase relations among mantle minerals are perturbed by the thermal environment of subducting slabs, both under equilibrium and disequilibrium (metastable) conditions. Such perturbations yield anomalies not only in seismic velocities but also in density. The buoyancy forces arising from these density anomalies may exert several important effects. They contribute to the stress field within the slab, in a fashion consistent with observed patterns of seismicity. They may affect subduction rates, both by inducing time-dependent velocity changes under equilibrium conditions and by imposing velocity limits through a thermal feedback loop under disequilibrium conditions. They may affect slab morphology, possibly inhibiting penetration of slabs into the lower mantle and allowing temporary stagnation of deflected or detached slabs. Latent heat release from phase transitions under disequilibrium conditions in slabs can yield isobaric superheating, which may generate adiabatic shear instabilities capable of triggering deep seismicity.