The Lithosphere-Asthenosphere Boundary
Lithosphere Asthenosphere dry, melt-free? hydrated? partial melt? Geotherm t Temperature Viscosity Isotropic velocity Figure 1 Schematic models of lithosphere-asthenosphere boundary (LAB) properties (a)Depthprofilethroughthe lithosphere and asthenosphere Arrows show the motion of a coherent lithospheric layer over a deforming asthenosphere
Lithosphere, Asthenosphere, and Perisphere
lithosphere [Wiens and Stein, 1983; Zoback, 1992] The asthenosphere will flow readily at much lower stress levels Asthenospheric viscosities are of the order of 1021 to 10 TM Pa s The lithosphere is generally assumed to have viscosities 2 or 3 orders of magnitude higher According to Barrell [ 1914], the lithosphere is
Viscous coupling at the lithosphere asthenosphere boundary
simple lithosphere‐asthenosphere model, shown in Figure 2 In this model, the thermal lid thickness, marked by an isotherm, T L, increases with distance from the ridge, x, as a result of continuous cooling to the surface The rate of thermal lid thickening decreases away from the ridge The relatively cold temperatures of the lithosphere lead
What makes the lithosphere strong and the asthenosphere weak?
Australia: Sp (Ford et al , in prep) 0 500 1000 1500 2000 2500 3000 Distance (km) AA’ (a) (b) 0 50 TOO YNGARMA EIDS CTAO COEN • Sharp LAB beneath Phanerozoic 100 150 E Australia
Lithosphere-Asthenosphere Interaction Beneath The Western US
Hunen et al 2002; English et al 2003; Saleeby 2003; DeCelles 2004; O’Driscoll et al 2009) is thought to have controlled the intense phase of crustal shortening, uplift and lithosphere modification (metasomatism) during the Sevier-Laramide orogenies (140-
La un peu de asthénosphère relations entre lithosphère et
Afficher les séismes (sélectionner toutes les magnitudes CAD > à 3) et le volcanisme au niveau de la carte - Définir et tracer la coupe au niveau du Pérou - Chili (à l’échelle 1) Pour cela, placer le point 1 du curseur en avant de la fosse (à l’ouest de celle-ci) et le point 2 juste au-delà des séismes profonds (à l’est)
GEOPHYSICS Tomography reveals buoyant asthenosphere
entire oceanic lithosphere The presence of this feature could have major implications for our understanding of the asthenosphere and subduction zone dynamics T he physical causes of the lithosphere-asthenosphereboundary(LAB),possiblyrep-resentingazonethatme chanicallydecouples tectonic plates from th e asthenospheric man-
The density structure of subcontinental lithosphere through time
Gri⁄n and Ryan [13] and Ryan et al [6] have shown that beneath many volcanic provinces there is a sharply de¢ned maximum depth at which garnets depleted in yttrium (a lithosphere signature) are common (Fig 3) They have argued that this depth represents the base of the petro-logically de¢ned lithosphere, and thus corre-sponds to the LAB
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