1932

Abstract

Seismological models of upper-mantle structure are providing new constraints on the physical and chemical properties that differentiate the lithosphere from the asthenosphere. A wide variety of studies are consistent with an oceanic lithosphere that corresponds to a dry, chemically depleted layer over a hydrated, fertile asthenosphere. At the lithosphere-asthenosphere boundary beneath oceans and many Phanerozoic continental regions, observed seismic velocity gradients require a contrast in mantle hydration, fertility, and/or melt content, perhaps in combination with a vertical gradient in velocity anisotropy. Beneath cratons, evidence is growing for a deeper—but globally ubiquitous—asthenosphere. Some studies conclude that the cratonic lithosphere-asthenosphere boundary is gradual enough to be matched by a purely thermal gradient, whereas others indicate a more rapid transition and a contrast in composition or perhaps melt content.

Loading

Article metrics loading...

/content/journals/10.1146/annurev-earth-040809-152438
2010-05-30
2024-04-18
Loading full text...

Full text loading...

/content/journals/10.1146/annurev-earth-040809-152438
Loading
/content/journals/10.1146/annurev-earth-040809-152438
Loading

Data & Media loading...

  • Article Type: Review Article
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error