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Title: Quantification of water in hydrous ringwoodite

Abstract

Here, ringwoodite, γ-(Mg,Fe) 2SiO 4, in the lower 150 km of Earth’s mantle transition zone (410-660 km depth) can incorporate up to 1.5-2 wt% H 2O as hydroxyl defects. We present a mineral-specific IR calibration for the absolute water content in hydrous ringwoodite by combining results from Raman spectroscopy, secondary ion mass spectrometery (SIMS) and proton-proton (pp)-scattering on a suite of synthetic Mg- and Fe-bearing hydrous ringwoodites. H 2O concentrations in the crystals studied here range from 0.46 to 1.7 wt% H 2O (absolute methods), with the maximum H 2O in the same sample giving 2.5 wt% by SIMS calibration. Anchoring our spectroscopic results to absolute H-atom concentrations from pp-scattering measurements, we report frequency-dependent integrated IR-absorption coefficients for water in ringwoodite ranging from 78180 to 158880 L mol -1cm -2, depending upon frequency of the OH absorption. We further report a linear wavenumber IR calibration for H 2O quantification in hydrous ringwoodite across the Mg 2SiO 4-Fe 2SiO 4 solid solution, which will lead to more accurate estimations of the water content in both laboratory-grown and naturally occurring ringwoodites. Re-evaluation of the IR spectrum for a natural hydrous ringwoodite inclusion in diamond from the study of the crystal contains 1.43more » ± 0.27 wt% H 2O, thus confirming near-maximum amounts of H 2O for this sample from the transition zone.« less

Authors:
 [1];  [2];  [2];  [3];  [3];  [4];  [5];  [6];  [3]
  1. Univ. of Nevada, Las Vegas, NV (United States)
  2. Northwestern Univ., Evanston, IL (United States)
  3. Univ. de Bundeswehr Munchen, Neubiberg (Germany)
  4. Carnegie Inst. of Washington, Washington, D.C. (United States)
  5. Helmholtz-Zentrum Potsdam, Deutsches GeoForschungsZentrum (GFZ), Potsdam (Germany)
  6. Univ. of Colorado, Boulder, CO (United States)
Publication Date:
Research Org.:
Carnegie Inst. of Washington, Washington, DC (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1335510
Grant/Contract Number:  
NA0002006; EAR-1215957; EAR-0748707
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Frontiers in Earth Science
Additional Journal Information:
Journal Volume: 2; Journal ID: ISSN 2296-6463
Publisher:
Frontiers Research Foundation
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; IR spectroscopy; water in nominally anhydrous minerals; transition zone; mineral-specific absorption coefficient; SIMS; Raman spectroscopy; proton-proton scattering; ringwoodite

Citation Formats

Thomas, Sylvia -Monique, Jacobsen, Steven D., Bina, Craig R., Reichart, Patrick, Moser, Marcus, Hauri, Erik H., Koch-Muller, Monika, Smyth, Joseph R., and Dollinger, Gunther. Quantification of water in hydrous ringwoodite. United States: N. p., 2015. Web. doi:10.3389/feart.2014.00038.
Thomas, Sylvia -Monique, Jacobsen, Steven D., Bina, Craig R., Reichart, Patrick, Moser, Marcus, Hauri, Erik H., Koch-Muller, Monika, Smyth, Joseph R., & Dollinger, Gunther. Quantification of water in hydrous ringwoodite. United States. doi:10.3389/feart.2014.00038.
Thomas, Sylvia -Monique, Jacobsen, Steven D., Bina, Craig R., Reichart, Patrick, Moser, Marcus, Hauri, Erik H., Koch-Muller, Monika, Smyth, Joseph R., and Dollinger, Gunther. Wed . "Quantification of water in hydrous ringwoodite". United States. doi:10.3389/feart.2014.00038. https://www.osti.gov/servlets/purl/1335510.
@article{osti_1335510,
title = {Quantification of water in hydrous ringwoodite},
author = {Thomas, Sylvia -Monique and Jacobsen, Steven D. and Bina, Craig R. and Reichart, Patrick and Moser, Marcus and Hauri, Erik H. and Koch-Muller, Monika and Smyth, Joseph R. and Dollinger, Gunther},
abstractNote = {Here, ringwoodite, γ-(Mg,Fe)2SiO4, in the lower 150 km of Earth’s mantle transition zone (410-660 km depth) can incorporate up to 1.5-2 wt% H2O as hydroxyl defects. We present a mineral-specific IR calibration for the absolute water content in hydrous ringwoodite by combining results from Raman spectroscopy, secondary ion mass spectrometery (SIMS) and proton-proton (pp)-scattering on a suite of synthetic Mg- and Fe-bearing hydrous ringwoodites. H2O concentrations in the crystals studied here range from 0.46 to 1.7 wt% H2O (absolute methods), with the maximum H2O in the same sample giving 2.5 wt% by SIMS calibration. Anchoring our spectroscopic results to absolute H-atom concentrations from pp-scattering measurements, we report frequency-dependent integrated IR-absorption coefficients for water in ringwoodite ranging from 78180 to 158880 L mol-1cm-2, depending upon frequency of the OH absorption. We further report a linear wavenumber IR calibration for H2O quantification in hydrous ringwoodite across the Mg2SiO4-Fe2SiO4 solid solution, which will lead to more accurate estimations of the water content in both laboratory-grown and naturally occurring ringwoodites. Re-evaluation of the IR spectrum for a natural hydrous ringwoodite inclusion in diamond from the study of the crystal contains 1.43 ± 0.27 wt% H2O, thus confirming near-maximum amounts of H2O for this sample from the transition zone.},
doi = {10.3389/feart.2014.00038},
journal = {Frontiers in Earth Science},
number = ,
volume = 2,
place = {United States},
year = {Wed Jan 28 00:00:00 EST 2015},
month = {Wed Jan 28 00:00:00 EST 2015}
}

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