Abstract
Geophysical studies have revealed the existence of regions with major shear wave velocity anomalies both within the top and bottom boundary layers of the mantle. Characteristic of both anomalous regions are their steep lateral gradients, i.e. relatively sharp 'edges', and their large vertical extent into the mantle. At the top of the mantle, positive shear wave velocity anomalies are found below Archean cratons and show that the cratonic lithosphere roots extend down to 300 km from the surface of our planet into the mantle. At the bottom boundary, the two anti-podal, equatorial Large Low Shear Velocity Provinces (LLSVPs) reach up to 1000 km from the core-mantle boundary (CMB) into the mantle. At a first glance, top and bottom boundary anomalies may seem to represent pronounced low and high temperature anomalies, respectively, with associated buoyancy forces directed away from the boundaries, a state which would imply convective instability. Instead, both cratonic roots and LLSVPs have remained stable features throughout long geological time. The sharp lateral gradients of cratons and LLSVPs with the surrounding mantle are supposedly associated with strong convection currents at the sides of the anomalies. (Author)
Citation Formats
Beuchert, Marcus.
Viscoelasticity, centrifugal forces and long-term stability of boundary layer anomalies in mantle convection models.
Norway: N. p.,
2010.
Web.
Beuchert, Marcus.
Viscoelasticity, centrifugal forces and long-term stability of boundary layer anomalies in mantle convection models.
Norway.
Beuchert, Marcus.
2010.
"Viscoelasticity, centrifugal forces and long-term stability of boundary layer anomalies in mantle convection models."
Norway.
@misc{etde_1010766,
title = {Viscoelasticity, centrifugal forces and long-term stability of boundary layer anomalies in mantle convection models}
author = {Beuchert, Marcus}
abstractNote = {Geophysical studies have revealed the existence of regions with major shear wave velocity anomalies both within the top and bottom boundary layers of the mantle. Characteristic of both anomalous regions are their steep lateral gradients, i.e. relatively sharp 'edges', and their large vertical extent into the mantle. At the top of the mantle, positive shear wave velocity anomalies are found below Archean cratons and show that the cratonic lithosphere roots extend down to 300 km from the surface of our planet into the mantle. At the bottom boundary, the two anti-podal, equatorial Large Low Shear Velocity Provinces (LLSVPs) reach up to 1000 km from the core-mantle boundary (CMB) into the mantle. At a first glance, top and bottom boundary anomalies may seem to represent pronounced low and high temperature anomalies, respectively, with associated buoyancy forces directed away from the boundaries, a state which would imply convective instability. Instead, both cratonic roots and LLSVPs have remained stable features throughout long geological time. The sharp lateral gradients of cratons and LLSVPs with the surrounding mantle are supposedly associated with strong convection currents at the sides of the anomalies. (Author)}
place = {Norway}
year = {2010}
month = {Jul}
}
title = {Viscoelasticity, centrifugal forces and long-term stability of boundary layer anomalies in mantle convection models}
author = {Beuchert, Marcus}
abstractNote = {Geophysical studies have revealed the existence of regions with major shear wave velocity anomalies both within the top and bottom boundary layers of the mantle. Characteristic of both anomalous regions are their steep lateral gradients, i.e. relatively sharp 'edges', and their large vertical extent into the mantle. At the top of the mantle, positive shear wave velocity anomalies are found below Archean cratons and show that the cratonic lithosphere roots extend down to 300 km from the surface of our planet into the mantle. At the bottom boundary, the two anti-podal, equatorial Large Low Shear Velocity Provinces (LLSVPs) reach up to 1000 km from the core-mantle boundary (CMB) into the mantle. At a first glance, top and bottom boundary anomalies may seem to represent pronounced low and high temperature anomalies, respectively, with associated buoyancy forces directed away from the boundaries, a state which would imply convective instability. Instead, both cratonic roots and LLSVPs have remained stable features throughout long geological time. The sharp lateral gradients of cratons and LLSVPs with the surrounding mantle are supposedly associated with strong convection currents at the sides of the anomalies. (Author)}
place = {Norway}
year = {2010}
month = {Jul}
}