Seismic imaging, plate velocities and geoid: the direct and inverse problem
| Autor: | Yanick Ricard, Claude Froidevaux |
|---|---|
| Přispěvatelé: | Laboratoire de Sciences de la Terre (LST), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), ricard, yanick |
| Jazyk: | angličtina |
| Rok vydání: | 1990 |
| Předmět: |
010504 meteorology & atmospheric sciences
Mantle wedge [PHYS.PHYS.PHYS-GEO-PH] Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] Geophysics 010502 geochemistry & geophysics Geodesy 01 natural sciences Mantle (geology) Physics::Geophysics Physics::Fluid Dynamics Mantle convection 13. Climate action Asthenosphere Seismic tomography Core–mantle boundary Geoid Slab Geology 0105 earth and related environmental sciences |
| Zdroj: | pp.553-569, 1990 Scopus-Elsevier Glacial Isostasy, Sea-Level and Mantle Rheology ISBN: 9789401054928 |
| Popis: | The dynamics of the Earth’s mantle, which has a clear signature at the surface in the form of plate motion, can only be investigated indirectly. The geoid reflects the density heterogeneities driving this mantle circulation. Recent tomographic models mapping lateral seismic velocity variations can help defining at first order the deep mass anomalies. We discuss a physical model based on a viscous mantle with rigid surface plates. The mantle circulation excited by seismically defined density heterogeneities is computed. It is highly 3-D, and exhibits two major upwellings located beneath the two observed geoid highs. The surface plates are depicted in the framework of spherical harmonics up to degree 15, and their predicted velocities agree well with observations when the upper mantle viscosity amounts to 2. × 1020 Pa.s. and the lower mantle is 50 times more viscous. The same physical model is then used to solve the inverse problem, where plate velocities, geoid and plate surface topography are used as constraints for predicting the best mantle viscosity profile. It increases smoothly by two orders of magnitude from the asthenosphere to the middle of the lower mantle, and decreases again approaching the core. Furthermore the inversion predicts a 3-D density distribution with better slab definition than derived from seismic tomography. |
| Databáze: | OpenAIRE |
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