Degree-one mantle convection: Dependence on internal heating and temperature-dependent rheology

Allen K. McNamara, Shijie Zhong

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

Geophysical and geological observations suggest that a degree-one mantle flow pattern, consisting of one upwelling and one downwelling, may have existed at some time in the mantles of Mars, the Moon, and perhaps even for the Earth during times of supercontinent formation. Simple fluid experiments utilizing isoviscous rheologies predict shorter wavelength flow patterns, and it is therefore important to determine fluid dynamical parameter sets which lead to larger wavelength flow patterns consistent with observations. We perform a series of numerical fluid dynamics calculations in a spherical 3-D geometry in which we vary Rayleigh number, rheological activation parameter, and the degree of internal heating in order to define which parameter choices can lead to degree-one mantle convection. We find that increasing the degree of internal heating increases the interior temperature of the mantle which leads to a larger viscosity contrast across the top thermal boundary layer, and that degree-one mantle flow occurs only in cases which exhibit internal heating, utilize activation coefficients which lead to 103 or higher viscosity contrasts across the mantle, and have viscosity contrasts across the top thermal boundary layer within the range of 200-3000.

Original languageEnglish (US)
Pages (from-to)1-5
Number of pages5
JournalGeophysical Research Letters
Volume32
Issue number1
DOIs
StatePublished - Jan 16 2005

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mantle convection
rheology
Earth mantle
convection
mantle
heating
flow pattern
viscosity
thermal boundary layer
flow distribution
temperature
boundary layer
wavelength
Rayleigh number
activation
fluid
supercontinent
fluid dynamics
downwelling
fluids

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)

Cite this

Degree-one mantle convection : Dependence on internal heating and temperature-dependent rheology. / McNamara, Allen K.; Zhong, Shijie.

In: Geophysical Research Letters, Vol. 32, No. 1, 16.01.2005, p. 1-5.

Research output: Contribution to journalArticle

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