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Electronic environments of ferrous iron in rhyolitic and basaltic glasses at high pressure

Solomatova, Natalia V. and Jackson, Jennifer M. and Sturhahn, Wolfgang and Rossman, George R. and Roskosz, Mathieu (2017) Electronic environments of ferrous iron in rhyolitic and basaltic glasses at high pressure. Journal of Geophysical Research. Solid Earth . ISSN 2169-9313. (In Press) http://resolver.caltech.edu/CaltechAUTHORS:20170831-141936485

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Abstract

The physical properties of silicate melts within Earth's mantle affect the chemical and thermal evolution of its interior. Chemistry and coordination environments affect such properties. We have measured the hyperfine parameters of iron-bearing rhyolitic and basaltic glasses up to ~120 GPa and ~100 GPa, respectively, in a neon pressure medium using time domain synchrotron Mössbauer spectroscopy. The spectra for rhyolitic and basaltic glasses are well explained by three high-spin Fe^(2+)-like sites with distinct quadrupole splittings. Absence of detectable ferric iron was confirmed with optical absorption spectroscopy. The sites with relatively high and intermediate quadrupole splittings are likely a result of fivefold and sixfold coordination environments of ferrous iron that transition to higher coordination with increasing pressure. The ferrous site with a relatively low quadrupole splitting and isomer shift at low pressures may be related to a fourfold or a second fivefold ferrous iron site, which transitions to higher coordination in basaltic glass, but likely remains in low coordination in rhyolitic glass. These results indicate that iron experiences changes in its coordination environment with increasing pressure without undergoing a high-spin to low-spin transition. We compare our results to the hyperfine parameters of silicate glasses of different compositions. With the assumption that coordination environments in silicate glasses may serve as a good indicator for those in a melt, this study suggests that ferrous iron in chemically complex silicate melts likely exists in a high-spin state throughout most of Earth's mantle.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1002/2017JB014363DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2017JB014363/abstractPublisherArticle
ORCID:
AuthorORCID
Solomatova, Natalia V.0000-0002-2331-3427
Rossman, George R.0000-0002-4571-6884
Additional Information:© 2017 American Geophysical Union. Received 22 APR 2017; Accepted 9 AUG 2017; Accepted article online 14 AUG 2017. We would like to thank E.E. Alp and W. Bi for isomer shift measurements of the reference stainless steel foils, D. Zhang and R.A. Morrison for their assistance with the measurements, and T.S. Toellner for valuable discussions. We are thankful to NSF-CSEDI-EAR-1600956, NSF-EAR-1322082, and the Keck Institute for Space Studies for financial support. We acknowledge COMPRES for partial support of Sector 3 and the Mössbauer Laboratory at the Advanced Photon Source (APS). This work was supported by the French ANR Program (2011JS56 004 01, FrIHIDDA) and by the Region Nord-Pas de Calais to M.R. Ruby fluorescence measurements were conducted at GSECARS and HPCAT at the APS. Use of the APS is supported by U.S. DOE, Office of Science (DE-AC02-06CH11357). We thank two anonymous reviewers for their thoughtful comments. The composition of the glasses, the hyperfine data, and select correlation matrices are tabulated in this manuscript; additional data may be obtained from N.V. Solomatova. The CONUSS software, developed by W. Sturhahn, is open source and available at http://www.nrixs.com/conuss.html.
Group:Seismological Laboratory, Keck Institute for Space Studies
Funders:
Funding AgencyGrant Number
NSFEAR-1600956
NSFEAR-1322082
Keck Institute for Space Studies (KISS)UNSPECIFIED
Agence Nationale pour la Recherche (ANR)2011JS56 004 01
Region Nord-Pas de CalaisUNSPECIFIED
Department of Energy (DOE)DE-AC02-06CH11357
Subject Keywords:silicate glass; silicate melt; Mossbauer spectroscopy; high pressure; coordination environment; ferrous iron
Record Number:CaltechAUTHORS:20170831-141936485
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20170831-141936485
Official Citation:Solomatova, N. V., J. M. Jackson, W. Sturhahn, G. R. Rossman, and M. Roskosz (2017), Electronic environments of ferrous iron in rhyolitic and basaltic glasses at high pressure, J. Geophys. Res. Solid Earth, 122, doi:10.1002/2017JB014363
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81035
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:31 Aug 2017 21:31
Last Modified:31 Aug 2017 21:31

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