Thermoelastic properties of zircon: Implications for geothermobarometry
- Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, U.S.A.
- Department of Earth and Environmental Sciences, University of Pavia, Via A. Ferrata, 1 27100 Pavia, Italy
- IGG CNR, Via Giovanni Gradenigo, 6, 35131 Padova, Italy
- Bayerisches Geoinstitut, Universität Bayreuth Universitätsstraße 30, 95447 Bayreuth, Germany
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, U.K.
Abstract A thermal-pressure equation of state has been determined for zircon (ZrSiO4) that characterizes its thermoelastic behavior at metamorphic conditions. New pressure-volume (P-V) data from a “Mud Tank” zircon have been collected from 1 bar to 8.47(1) GPa using X-ray diffraction, and elastic moduli were measured from room temperature up to 1172 K by resonance ultrasound spectroscopy. These data were fitted simultaneously with temperature-volume (T-V) data from the literature in EosFit7c using a new scaling technique. The parameters of a third-order Birch-Murnaghan EoS with a Mie-Grüneisen-Debye model for thermal pressure have compressional EoS parameters K0T = 224.5(1.2) GPa, K0T' = 4.90(31) with a fixed initial molar volume V0 = 39.26 cm3/mol and thermal parameters γ0 = 0.868(15), q = 2.37(80), and ΘD = 848(38) K. EoS parameters that describe the variation of unit-cell parameters with pressure and temperature were determined using an isothermal-type EoS. This new EoS confirms that zircons are stiffer than garnets and exhibit a much lower thermal expansion. This results in steep isomekes between zircon and garnets, which makes zircon trapped as inclusions in garnets at metamorphic conditions a good piezothermometer.
- Research Organization:
- Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- SC0016448
- OSTI ID:
- 1981039
- Journal Information:
- American Mineralogist, Vol. 107, Issue 1; ISSN 0003-004X
- Publisher:
- Mineralogical Society of America
- Country of Publication:
- United States
- Language:
- English
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