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Thermal expansion of mantle and core materials at very high pressures

Duffy, Thomas S. and Ahrens, Thomas J. (1993) Thermal expansion of mantle and core materials at very high pressures. Geophysical Research Letters, 20 (11). pp. 1103-1106. ISSN 0094-8276. doi:10.1029/93GL00479.

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The thermal expansivities (α) of MgO and high-pressure phases of CaO, CaMgSi_2O_6, and Fe at ultrahigh pressure are obtained by comparing existing shock compression and temperature measurements to 300 K compression curves constructed from ultrasonic elasticity and static compression data. For MgO, α can be represented by: α = ρ_oγ_oC_V(ρ_o/ρ)^(0.5±0.5)/K_T where γ is the Grüneisen parameter, C_V is the constant volume specific heat, K_T is the isothermal bulk modulus, and ρ is the density. Using this expression, the thermal expansivity of MgO is 28-32×10^(−6)K^(−1) at the pressure of the top of the lower mantle and 10-16×10^(−6)K^(−1) at its base (at 2000 K). New data for α of ε-Fe, together with an inner core temperature of 6750 K, constrain the density of the inner core to be 5±2% less than the density of ε-Fe, implying the inner core contains a light element.

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Additional Information:© 1993 by the American Geophysical Union. Paper number 93GL00479. Received June 26, 1992; revised January 28, 1993; accepted February 25, 1993. We appreciate the comments of D. Isaak, O. L. Anderson, and two reviewers on an earlier version of this manuscript. This research was supported by the NSF. Division of Geological and Planetary Sciences, California Institute of Technology contribution 5165.
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Caltech Division of Geological and Planetary Sciences5165
Issue or Number:11
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ID Code:50810
Deposited By: Tony Diaz
Deposited On:24 Oct 2014 22:39
Last Modified:10 Nov 2021 19:01

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