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Direct shock compression experiments on premolten forsterite and progress toward a consistent high-pressure equation of state for CaO-MgO-Al_2O_3-SiO_2-FeO liquids

Thomas, Claire W. and Asimow, Paul D. (2013) Direct shock compression experiments on premolten forsterite and progress toward a consistent high-pressure equation of state for CaO-MgO-Al_2O_3-SiO_2-FeO liquids. Journal of Geophysical Research. Solid Earth, 118 (11). pp. 5738-5752. ISSN 2169-9313. doi:10.1002/jgrb.50374. https://resolver.caltech.edu/CaltechAUTHORS:20140114-104523180

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Abstract

We performed shock compression experiments on preheated forsterite liquid (Mg_2SiO_4) at an initial temperature of 2273 K and have revised the equation of state (EOS) that was previously determined by shock melting of initially solid Mg_2SiO_4 (300 K). The linear Hugoniot, U_S = 2.674 ± 0.188 + 1.64 ± 0.06 u_p km/s, constrains the bulk sound speed within a temperature and composition space as yet unexplored by 1 bar ultrasonic experiments. We have also revised the EOS for enstatite liquid (MgSiO_3) to exclude experiments that may have been only partially melted upon shock compression and also the EOS for anorthite (CaAl_2SiO_6) liquid, which now excludes potentially unrelaxed experiments at low pressure. The revised fits and the previously determined EOS of fayalite and diopside (CaMg_2SiO_6) were used to produce isentropes in the multicomponent CaO-MgO-Al_2O_3-SiO_2-FeO system at elevated temperatures and pressures. Our results are similar to those previously presented for peridotite and simplified “chondrite” liquids such that regardless of where crystallization first occurs, the liquidus solid sinks upon formation. This process is not conducive to the formation of a basal magma ocean. We also examined the chemical and physical plausibility of the partial melt hypothesis to explain the occurrence and characteristics of ultra-low velocity zones (ULVZ). We determined that the ambient mantle cannot produce an equilibrium partial melt and residue that is sufficiently dense to be an ultra-low velocity zone mush. The partial melt would need to be segregated from its equilibrium residue and combined with a denser solid component to achieve a sufficiently large aggregate density.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1002/jgrb.50374DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/jgrb.50374/abstractPublisherArticle
ORCID:
AuthorORCID
Asimow, Paul D.0000-0001-6025-8925
Additional Information:© 2013 American Geophysical Union. Received 28 March 2013; revised 7 August 2013; accepted 13 September 2013; published 11 November 2013. The authors would like to thank the shock wave lab technical staff—Oleg Fat’yanov, Eprapodito Gelle, and Russel Oliver, and also Denis Andrault and an anonymous reviewer for their helpful comments. This work was supported by the National Science Foundation through award EAR-1119522.
Funders:
Funding AgencyGrant Number
NSFEAR-1119522
Subject Keywords: equation of state; shock compression; silicate liquids; magma oceans; ULVZ
Issue or Number:11
DOI:10.1002/jgrb.50374
Record Number:CaltechAUTHORS:20140114-104523180
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140114-104523180
Official Citation:Thomas, C. W., and P. D. Asimow (2013), Direct shock compression experiments on premolten forsterite and progress toward a consistent high-pressure equation of state for CaO-MgO-Al2O3-SiO2-FeO liquids, J. Geophys. Res. Solid Earth, 118, 5738–5752, doi:10.1002/jgrb.50374.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43357
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:14 Jan 2014 19:25
Last Modified:10 Nov 2021 16:36

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