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Instabilities from phase transitions and the timescales of mantle thermal evolution
Author(s) -
Steinbach Volker,
Yuen David A.,
Zhao Wuling
Publication year - 1993
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 - 10.1029/93gl01243
Subject(s) - mantle (geology) , mantle convection , convection , thermal , geophysics , geology , earth's internal heat budget , transition zone , layering , rayleigh number , natural convection , thermodynamics , physics , lithosphere , seismology , botany , biology , tectonics
We have investigated the effects of mantle phase‐transitions on the Earth's thermal evolution by numerical modelling. Our results show that the tendency of layering grows with increasing vigor of convection. A self‐consistent model which couples the convective dynamics of the mantle to the secular cooling of the core is constructed. For a temperature‐dependent effective viscosity, we found that the thermal history of the Earth is characterized by two timescales, one is associated with layered convection in the early period, which is followed by a transition period with dramatic overturns. As the Rayleigh number decreases sufficiently low, whole mantle convection prevails and a faster cooling timescale ensues.