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Adiabaticity and viscosity in deep mantle convection
Author(s) -
Quareni Francesca,
Yuen David A.,
Saari Marc R.
Publication year - 1986
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl013i001p00038
Subject(s) - mantle (geology) , adiabatic process , mantle convection , convection , rheology , internal heating , radiogenic nuclide , thermodynamics , geology , geophysics , physics , mechanics , lithosphere , paleontology , tectonics
We have studied steady convection with adiabatic and viscous heating for variable viscosity in the Boussinesq limit using the mean‐field theory. A strong nonlinear coupling is found between the thermodynamic constants governing adiabatic heating and the rheological parameters. We have established the range of rheological values for which adiabaticity would occur throughout the mantle. Too large an activation volume, greater than 6 cm³/mol for the cases examined here, would produce unreasonably high temperature at the bottom of the mantle (>6000 K) and superadiabatic gradients, especially in the lower mantle. Radiogenic heating plays a profound role in controlling dynamically mantle temperatures. Present values for the averaged mantle heat production would yield objectionably high temperatures in the lower mantle.