Low-velocity layer in upper mantle of western Tibet from Rayleigh wave tomography
Abstract
We present a shear velocity model for the crust and upper mantle beneath the Y2 array in western Tibet. The model is constrained by new measurements of the fundamental-mode Rayleigh wave phase velocity for periods from 20 to 60s. This dispersion data was derived using the two-plane-wave joint inversion method, including realistic sensitivity kernels to improve lateral resolution. To better constrain the crust, the dispersion data was combined with existing receiver function and group velocity data in a joint inversion for the final shear velocity model. The phase velocity data, which show slow velocities at long periods, indicate that there is a low velocity layer in the upper mantle of this region. In the best-fitting case, the layer, with Vs of around 4.2km s-1, begins at a depth of around 150km and extends to the limits of the study region at around 300km depth. The low-velocity layer could be interpreted as warm material upwelling following delamination, or might represent subducted Indian crust.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.T43B3043M
- Keywords:
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- 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICSDE: 8124 Earth's interior: composition and state;
- TECTONOPHYSICSDE: 8159 Rheology: crust and lithosphere;
- TECTONOPHYSICSDE: 8164 Stresses: crust and lithosphere;
- TECTONOPHYSICS