Academic Commons

Articles

Questions on the existence, persistence, and mechanical effects of a very small melt fraction in the asthenosphere

Holtzman, Benjamin K.

This paper integrates current questions in rock physics on the effects and behavior of very small melt fractions (<< 1%) in the asthenosphere. In experiment and theory, it has been shown that a very small melt fraction forming a connected network has a large effect on the diffusion creep shear viscosity, as well as in the anelastic behavior. Because small concentrations of volatiles, particularly H2O and CO2, significantly lower the peridotite solidus, a small melt fraction is expected in the asthenosphere. Even with connected networks, permeability will be low and surface tension will generate a strong force resisting complete draining of small melt fractions. The anelastic reduction of shear velocity due to melt could cause a ≥ 5% shear velocity contrast across the solidus, consistent with the contrast measured on features in the shallow suboceanic upper mantle that are often interpreted as the lithosphere-asthenosphere boundary.

Files

  • thumnail for Holtzman_G3_2016_corr__2_.pdf Holtzman_G3_2016_corr__2_.pdf application/pdf 2.33 MB Download File

Also Published In

Title
Geochemistry, Geophysics, Geosystems
DOI
https://doi.org/10.1002/2015GC006102

More About This Work