Spectral analysis of marine geoid heights and ocean depths: Constraints on models of lithospheric and sublithospheric processes |
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| Authors: | Martin T Black David C Mcadoo |
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| Institution: | (1) Astronomy Program, University of Maryland, 20742 College Park, MD, USA;(2) Geophysics Branch, NASA Goddard Space Flight Center Greenbelt, 20771, MD, USA;(3) National Geodetic Survey, Charting and Geodetic Services, National Ocean Service, National Oceanic and Atmospheric Administration, 20852 Rockville, MD, USA |
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| Abstract: | Cross-spectral analysis has been used to study the relationship between geoid and bathymetry in 16°×16° blocks in the oceans. The admittances resulting from this analysis have been compared with thermomechanical models of the lithosphere and sublithosphere in order to determine modes of topographic compensation in different parts of the oceans. Peak admittances at short wavelengths ( <800 km) indicate that loads are supported by the mechanical strength of the lithosphere, while peak admittances at long wavelengths (>800 km) are indicative of lithospheric cooling or dynamic sublithospheric processes. Models of upper mantle convection predict higher admittances at long wavelengths than do models of lithospheric cooling. In most areas the observed admittances can be explained by models of the thermomechanical properties of the lithosphere, but in the eastern Pacific Ocean, the northern Indian Ocean, and over the Cape Verde Rise high long-wavelength admittances are evidence for the existence of upper mantle convection. |
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| Keywords: | Geoid bathymetry admittance lithosphere convection isostasy |
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