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Dynamically supported geoid highs over hotspots - Observation and theoryHotspots are associated with long wavelength geoid highs, an association that is even stronger when the geoid highs associated with subduction zones are removed. These associations are quantified by expanding the hotspot distribution in spherical harmonics and calculating correlation coefficients as a function of harmonic degree. The hotspot distribution spectrum is essentially white, with peaks at degrees 2 and 6. It is correlated positively with the slab residual geoid for degrees 2 to 6, with low seismic velocity in the lower mantle at degree 2, and with low seismic velocity in the upper mantle at degree 6. A variety of fluid mechanical models were tested for hotspots, including lithospheric delamination and hot plumes, by calculating their predicted dynamic geoid responses and comparing them to the observations. These models include the effects of temperature dependent rheology. The preferred hotspot model, based on observations of the geoid and seismic tomography, has plumes preferentially occurring in regions of large scale background temperature highs in a mantle with substantial viscosity increase with depth, although other models are possible.
Document ID
19880059051
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Richards, Mark A.
(California Inst. of Tech. Pasadena, CA, United States)
Hager, Bradford H.
(California Institute of Technology Pasadena, United States)
Sleep, Norman H.
(Stanford University CA, United States)
Date Acquired
August 13, 2013
Publication Date
July 10, 1988
Publication Information
Publication: Journal of Geophysical Research
Volume: 93
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
88A46278
Funding Number(s)
CONTRACT_GRANT: NSG-7610
CONTRACT_GRANT: NAG5-315
Distribution Limits
Public
Copyright
Other

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