Recent seismological evidences imply that the boundary between the lithosphere and asthenosphere is a compositional boundary in the oceanic upper mantle, and a rapid increase of viscosity at this boundary is suggested. We modeled a thermal convection in the oceanic mantle numerically using the finite element method, and investigated geodynamical consequences of such a rheological layering. Earl...

A variety of geophysical data indicates that long wavelength temperature variations of the asthenosphere depart from the mean by + 200øC, not the + 20øC adopted by plume theoreticians. The 'normal' variation, caused by plate tectonic processes (subduction cooling, continental insulation, smallscale convection) encompasses the temperature excesses that have been attributed to hot jets and therma...

A simple model for the development and evolution of sedimentary basins is proposed. The first event consists of a rapid stretching of continental lithosphere, which produces thinning and passive upwelling of hot asthenosphere. This stage is associated with block faulting and subsidence. The lithosphere then thickens by heat conduction to the surface, and further slow subsidence occurs which is ...

Most of the earthquake faults in North-East India, China, mid Atlantic-ridge, the Pacific seismic belt and Japan are found to be predominantly dip-slip in nature. In the present paper a dip-slip fault is taken situated in an elastic layer over a viscoelastic half space representing the lithosphere-asthenosphere system. A movement of the dip-slip nature across the fault occurs when the accumulat...

Electrical conductivity of minerals is sensitive to water content and hence can be used to infer the water content in the mantle. However, previous studies to infer the water content in the upper mantle were based on pure olivine model of the upper mantle. Influence of other minerals particularly that of orthopyroxene needs to be included to obtain a better estimate of water content in view of ...

Since the beginning of the 1980s seismic tomography studies have helped to unravel the deep structure and to constrain the kinematic models of tectonic evolution of Italy. In this chapter I describe the main features of the upper mantle structure beneath the Tyrrhenian – Apennine system obtained by jointly analysing the tomographic results with the distribution of subcrustal earthquakes. A new ...

• S-wave velocity gradients with depth and absolute velocities in the Alaskan crust mantle. Thin upper plate lithosphere low asthenospheric reflect subduction effects. Thick high northern Alaska, part due to original tectonic terranes. The present-day lithospheric structure of Alaska is result a unique history terrane accretion that controls thickness rheology. To provide new constraints on man...

The eastern Tibetan Plateau has attracted widespread attention due to its complex topography and strong seismicity. However, the mechanism controlling growth of this margin remains enigmatic. Here, we present detailed upper mantle structures easternmost northeastern from dense-array adjoint waveform tomography. seismic images show mushroom-shaped low-velocity zones atop at uppermost slab-shaped...