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A finite strain approach to thermal expansivity's pressure dependence

George Helffrich
A finite strain approach to thermal expansivity's pressure dependence
American Mineralogist (August 2017) 102 (8): 1690-1695


The pressure dependence of thermal expansivity affects mineral density at pressure and is an extrapolator for calculating self-compression adiabats of a self-gravitating body. I review different models for the pressure dependence of expansivity and how to decide which performs best. A finite strain model, proposed here, performs better when used to calculate adiabatic temperature lapses in both the solid silicate and liquid metal parts of a planet than either an ad-hoc exponential dependence on pressure or a commonly used mineral physics model. Choosing a particular thermal expansivity pressure dependence leads to significantly different temperatures in planetary interiors, and to inferred subsolidus properties related to homologous melting temperature. In particular, thermal expansivity in liquid metal in planetary cores at pressures comparable to Earth's core is significantly affected. The universality of the parameterization provides a simple way to model rocky planet interiors in our solar system and exoplanet interiors.

ISSN: 0003-004X
EISSN: 1945-3027
Serial Title: American Mineralogist
Serial Volume: 102
Serial Issue: 8
Title: A finite strain approach to thermal expansivity's pressure dependence
Author(s): Helffrich, George
Affiliation: Tokyo Institute of Technology, Earth-Life Science Institute, Tokyo, Japan
Pages: 1690-1695
Published: 201708
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 30
Accession Number: 2017-076572
Categories: Extraterrestrial geologySolid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201740
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