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When does small-scale convection begin beneath oceanic lithosphere?A numerical model of small-scale convection in a fluid of variable viscosity is described. The results indicate that recently observed gravity anomalies showing a pattern of highs and lows aligned in the direction of oceanic plate motion may be the result of small-scale mantle flow. The convective flow must begin in the first six Myr of lithospheric cooling to produce the observed signals, which is not inconsistent with constraints on the viscosity of the mantle. The calculated trend for the subsidence of the ocean floor is found to be almost linear with the square root of time even when small-scale convection has significantly changed the rate of subsidence. For average shallow asthenospheric viscosities of about 10 to the 18th Pa/s, the model subsidence can match data for the oceans and reproduce the magnitude and wavelength of the observed gravity anomalies.
Document ID
19850044996
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Buck, W. R.
(Lamont-Doherty Geological Observatory, Palisades, NY; MIT, Cambridge MA, United States)
Date Acquired
August 12, 2013
Publication Date
February 28, 1985
Publication Information
Publication: Nature
Volume: 313
ISSN: 0028-0836
Subject Category
Geophysics
Accession Number
85A27147
Funding Number(s)
CONTRACT_GRANT: NAG5-41
Distribution Limits
Public
Copyright
Other

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