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Minimal upper mantle temperature variations consistent with observed heat flow and plate velocitiesHeat-flow and plate-velocity measurements are used to model upper-mantle temperature variations; the results are intended to form the basis for a gravity-field-variation model and are also applicable to the interpretation of petrological and seismological data. A 5-deg grid is used, a depth of 280 km is chosen as the fully convecting level, and it is assumed that 85 percent of the global heat production (4.0 x 10 to the 13th W) comes from below this level. The velocity field is calculated by integrating the momentum equations down to 280 km (assuming laterally homogeneous viscosity and density) and then used to determine the temperature fields. The results are presented in graphs, tables, and maps. The largest lateral temperature differences are about 1500 C and occur in the top 20 km, where the largest (about 200 C/Myr) nonlinear terms of the energy equation are also found. Below 50 km, heat transfer becomes more convective than conductive, and the most significant temperature variation appears in the form of negative 'tongues' as cold as -825 C at about 100 km. Temperature variations of at least + or - 180 C are calculated at the fully convecting level.
Document ID
19840035867
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Kaula, W. M.
(California, University Los Angeles, CA, United States)
Date Acquired
August 12, 2013
Publication Date
December 10, 1983
Publication Information
Publication: Journal of Geophysical Research
Volume: 88
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
84A18654
Funding Number(s)
CONTRACT_GRANT: NSG-5263
Distribution Limits
Public
Copyright
Other

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