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Shock temperature in calcite (CaCO_3) at 95–160 GPa

Gupta, Satish C. and Love, Stanley G. and Ahrens, Thomas J. (2002) Shock temperature in calcite (CaCO_3) at 95–160 GPa. Earth and Planetary Science Letters, 201 (1). pp. 1-12. ISSN 0012-821X. doi:10.1016/S0012-821X(02)00685-4. https://resolver.caltech.edu/CaltechAUTHORS:20141022-075611973

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Abstract

The temperatures induced in crystalline calcite (CaCO_3) upon planar shock compression (95–160 GPa) are reported from two-stage light gas gun experiments. Temperatures of 3300–5400 K are obtained by fitting six-channel optical pyrometer radiances in the 450–900 nm range to the Planck gray-body radiation law. Thermodynamic calculations demonstrate that these temperatures are some 400–1350 K lower than expected for vibronic excitations of the lattice with a 3R/mole-atom specific heat (R is gas constant). The temperature deficit along the Hugoniot is larger than that expected from only melting. In addition to melting, it appears likely that shock-induced decomposition of calcite occurs behind the shock front. We modeled disproportionation of calcite into CaO (solid) plus CO_2 (gas). For temperature calculations, specific heat at constant volume for 1 mole of CO_2 is taken to be 6.7R as compared to 9R in the solid state; whereas a mole of calcite and a mole of CaO have their solid state values 15R and 6R, respectively. Calculations suggest that the calcite decomposes to CaO and CO_2 at ∼110±10 GPa along the Hugoniot. Recent reanalysis of earlier VISAR measurements of particle velocity profiles [1] indicates that calcite shocked to 18 GPa undergoes disproportionation at much lower pressures upon isentropic expansion.


Item Type:Article
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http://dx.doi.org/10.1016/S0012-821X(02)00685-4 DOIArticle
http://www.sciencedirect.com/science/article/pii/S0012821X02006854PublisherArticle
Additional Information:© 2002 Elsevier Science B.V. Received 12 February 2002; accepted 13 April 2002. Research supported by NASA. We thank Kathleen Holland, Mike Long, Papo Gelle, and Alberto De Vora for technical help and assistance with this work. S.C.G. wishes to thank S.K. Sikka for his encouragement and support. Helpful suggestions of Toshimori Sekine and D.L. Heinz are thankfully acknowledged. Contribution No. 8677 Division of Geological and Planetary Sciences (Caltech).
Funders:
Funding AgencyGrant Number
NASAUNSPECIFIED
Subject Keywords:calcite; shock metamorphism; volatilization; melting
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences8677
Issue or Number:1
DOI:10.1016/S0012-821X(02)00685-4
Record Number:CaltechAUTHORS:20141022-075611973
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20141022-075611973
Official Citation:Satish C Gupta, Stanley G Love, Thomas J Ahrens, Shock temperature in calcite (CaCO3) at 95–160 GPa, Earth and Planetary Science Letters, Volume 201, Issue 1, 15 July 2002, Pages 1-12, ISSN 0012-821X, http://dx.doi.org/10.1016/S0012-821X(02)00685-4. (http://www.sciencedirect.com/science/article/pii/S0012821X02006854)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50656
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:22 Oct 2014 16:44
Last Modified:10 Nov 2021 18:58

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