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Elasticity of San Carlos olivine to 8 GPa and 1073 K
Author(s) -
Liu Wei,
Kung Jennifer,
Li Baosheng
Publication year - 2005
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 - 10.1029/2005gl023453
Subject(s) - olivine , geothermal gradient , mantle (geology) , geology , mineralogy , anhydrous , thermodynamics , elasticity (physics) , atmospheric temperature range , adiabatic process , analytical chemistry (journal) , bulk modulus , materials science , chemistry , geophysics , physics , organic chemistry , chromatography
Elasticity of San Carlos olivine, (Mg 0.9 , Fe 0.1 ) 2 SiO 4 , has been measured at simultaneous high pressure and high temperature to 8.2 GPa and 1073 K using ultrasonic interferometry in conjunction with synchrotron X‐radiation. The elastic moduli and their pressure and temperature derivatives are precisely determined using a pressure standard free fit using third‐order finite strain equations to the velocity and unit cell volume data in the entire pressure and temperature range, yielding K S 0 = 130.3(4) GPa, G 0 = 77.4(2) GPa, K ′ S 0 = 4.61(11), G ′ 0 = 1.61(4), ∂ K S /∂ T = −0.0164(5) GPa/K, and ∂ G /∂ T = −0.0130(3) GPa/K. Combined with previous thermoelastic data on wadsleyite, the velocity contrasts between α‐ and β‐(Mg, Fe) 2 SiO 4 at 410‐km depth are calculated along a 1673 K adiabatic geotherm with plausible iron partition between the two phases. The fraction of olivine consistent with a ∼5% seismic discontinuity in an anhydrous mantle is constrained to be less than ∼50% with the possibility that a hydrous or a cooler mantle increases the olivine content towards pyrolitic composition.