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The influence of interior mantle temperature on the structure of plumes: Heads for Venus, Tails for the Earth
Author(s) -
Jellinek A. Mark,
Lenardic Adrian,
Manga Michael
Publication year - 2002
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 - 10.1029/2001gl014624
Subject(s) - mantle (geology) , venus , geology , geophysics , plume , mantle convection , mantle plume , lithosphere , plate tectonics , convection , core–mantle boundary , boundary layer , subduction , thermal , viscosity , heat flux , upwelling , mechanics , tectonics , heat transfer , thermodynamics , astrobiology , seismology , physics , oceanography
To form mantle plumes with large heads and narrow trailing conduits requires large (>10 2 ) viscosity variations within the hot thermal boundary layer at the plume source. However, new and published data from laboratory experiments show that if a layer of fluid with a temperature‐dependent viscosity is heated from below and cooled from above, convection occurs beneath a stagnant lid, and the interior fluid temperature remains close to that of the hot boundary. Consequently, the viscosity reduction across the hot thermal boundary layer is always <10 and upwellings take the form of discrete plume heads (thermals). Subduction of the stagnant layer (equivalent to recycling lithospheric plates on the Earth) will cool the interior of the mantle, thus increasing the viscosity ratio. Hence, the existence of Earth‐like mantle plumes may be a consequence of plate tectonics. An absence of plate tectonics on Venus may lead to upwellings composed of thermals, the surface expression of which are coronae, as well as a smaller core heat flux than on Earth.