Upper mantle viscosity and dynamic subsidence of curved continental margins

Buoyancy of the continental upper mantle

[1] The thermal boundary layer beneath continental cratons extends into the Earth’s mantle to depths of at least 200 km. It has been proposed that chemical depletion of the lithospheric mantle during partial melting offsets the effect of increased density from conductive cooling, resulting in neutral buoyancy with respect to the underlying asthenosphere. Mineral compositions of garnet peridotit...

Imaging the continental upper mantle using electromagnetic methods

The internal structure of the continental lithosphere holds the key to its creation and development, and this internal structure can be determined using appropriate seismic and electromagnetic methods. These two are complementary in that the seismic parameters usually represent bulk properties of the rock, whereas electrical conductivity is primarily a function of the connectivity of a minor co...

Lateral variation in upper mantle viscosity: role of water

Differences in the viscosity of the earth’s upper mantle beneath the western US (f 10–10 Pa s) and global average values based on glacial isostatic adjustment and other data (f 10–10 Pa s) are generally ascribed to differences in temperature. We compile geochemical data on the water contents of western US lavas and mantle xenoliths, compare these data to water solubility in olivine, and calcula...

Building and Destroying Continental Mantle

Continents, especially their Archean cores, are underlain by thick thermal boundary layers that have been largely isolated from the convecting mantle over billion-year timescales, far exceeding the life span of oceanic thermal boundary layers. This longevity is promoted by the fact that continents are underlain by highly melt-depleted peridotites, which result in a chemically distinct boundary ...

Numerical Geodynamic Modeling of Continental Convergent Margins