Rheology of the mantle

The study of how Earth's solid mantle deforms and flows over geological timescales, from grain-scale creep to whole-mantle convection.

Dislocation creep: Deformation by motion of crystal defects through the lattice; strain rate depends weakly on grain size. The dominant deformation mechanism in much of the upper mantle, with its own distinctive flow law.
Low-velocity zone: A depth interval in the upper mantle where seismic waves slow, possibly marking partial melt or weakening. Whether it contains melt that decouples plates from the mantle remains disputed.
Creep: Slow, permanent deformation of solids under sustained stress below their breaking point. The general phenomenon of which mantle flow is the planetary-scale case.
Mantle convection: The slow circulation of solid mantle rock driven by internal heat, the engine beneath plate motion. Convection models solve the mantle flow laws to predict plate speeds and patterns.
Reginald Aldworth Daly: Harvard geologist who argued in the 1920s that the mantle behaves as a weak solid capable of flow. Early advocate that solid rock could flow, preparing geology for convection ideas.
Diffusion creep: Deformation by atoms diffusing along grain boundaries, making strain rate strongly grain-size dependent. Competes with dislocation creep; which one governs flow changes viscosity's grain-size dependence.
Mantle plumes: Narrow hot upwellings from the deep mantle proposed to explain intraplate volcanism like Hawaii. How plumes rise through a viscosity-stratified mantle tests convection models.
Newtonian fluid: A fluid whose strain rate is linearly proportional to applied stress. Mantle convection models often assume Newtonian behavior; real dislocation creep is non-linear.
Glacial isostatic adjustment: Ongoing deformation of Earth from loading and unloading by Pleistocene ice sheets. Inference of viscosity depth profiles from rebound shapes sea-level and ice-mass estimates.
Felix Chossudovsky: Not a recognized figure in mantle rheology or geophysics. Placeholder entry; no established contributions connect this name to mantle flow studies.

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