Premium
Thermal expansion of mantle minerals at high pressures—A theoretical study
Author(s) -
Reynard Bruno,
Price Geoffrey D.
Publication year - 1990
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/gl017i006p00689
Subject(s) - mantle (geology) , forsterite , thermal expansion , geology , thermodynamics , grüneisen parameter , post perovskite , core–mantle boundary , geophysics , mineralogy , materials science , physics
Recent experimental work has shown that the pressure dependence of the thermal expansion coefficient can be expressed as: where δ T , the Anderson‐Gruneisen parameter, is assumed to be independent of pressure, and for the materials studied has a value that lies between 4 and 6. Calculation of δ T from seismic data, however, appears to suggest a contradictory value of between 2 and 3 for mantle‐forming phases. Using an atomistic model based on our previously successful many‐body interatomic potential set (THBl), we have performed calculations to obtain values of δ T for four major mantle‐forming minerals. Our model results are in excellent agreement with experimental data, yielding values of between 4 and 6 for forsterite and MgO, and values in the same range for MgSiO 3− perovskite and γ‐Mg 2 SiO 4 . Moreover, the calculations confirm that δ T is indeed constant with pressure up to the core‐mantle boundary. The apparent conflict between the values of δ T predicted from seismic data and those obtained from experiment, and now from theory, is discussed.