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Mobility of chromium in high temperature crustal and upper mantle fluids

J. Huang1,

1Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA

J. Hao1,2,

1Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
2Laboratoire de Geologie de Lyon, Observatoire de Lyon, Universite Claude Bernard Lyon1, 69007 Lyon, France

F. Huang1,3,

1Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
3Rensselaer Polytechnic Institute, NY 12180, USA

D.A. Sverjensky1

1Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA

Affiliations  |  Corresponding Author  |  Cite as  |  Funding information

Huang, J., Hao, J., Huang, F., Sverjensky, D.A. (2019) Mobility of chromium in high temperature crustal and upper mantle fluids. Geochem. Persp. Let. 12, 1–6.

Johns Hopkins University, Deep Carbon Observatory, National Science Foundation, Department of Energy.

Geochemical Perspectives Letters 12  |  doi: 10.7185/geochemlet.1926
Received 18 March 2019  |  Accepted 26 July 2019  |  Published 13 November 2019
Copyright © The Authors

Published by the European Association of Geochemistry
under Creative Commons License CC BY-NC-ND 4.0




Figure 1 (a, b) Effect of temperature and pressure on the valence state of ions at 25 °C and Psat (dashed lines), 200 °C and Psat (dotted dashed lines) and 600 °C and 2.0 GPa (solid lines). Horizontal lines represent the QFM buffer (black): (a) Fe3+/Fe2+ (orange) and Cr3+/Cr2+ (green) (b) Cu2+/Cu+ (blue) and Cr3+/Cr2+ (green). (c, d) Experimental Cr2O3 solubilities in HCl-rich fluids at 500–700 °C and 0.1–1.0 GPa. (c) HCl = 1.646 mol kg-1. (d) HCl = 2.249 mol kg-1. Solid curves are fitted to the experimental data at QFM + 1.
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Figure 2 Experimental Cr2O3 solubilities in KCl fluids at 1000 °C and 4.0 GPa. Curves were fit to the highest two KCl points from QFM - 2 to QFM + 2.
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Figure 3 Regression of log K for CrCl(OH)0 for dissociation reaction versus (a) pressure and (b) temperature up to 6.0 GPa and 1100 °C.
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Figure 4 Prediction of Cr solubility in model fluids. (a) MOR, subduction zone, and diamond-forming fluids. (b) mafic eclogitic fluid at 570 °C and 2.0 GPa, Cr concentration versus Cl at QFM (red), QFM - 1 (green) and QFM - 2 (blue). Effects of Cl concentration and activity of Cr species on the solubility of Cr2O3(s) and Cr speciation at 600 °C and 2.0 GPa: (c) a(Cl-) = 0.5 (solid blue), 1 (dashed green) and 2 (dashed red) mol kg-1, assuming a(CrCl(OH)0) = a(Cr(OH4)< = 10-5 mol kg-1. (d) a(CrCl(OH)0) = a(Cr(OH4)) = 10-5 (solid blue), 10-4 (dashed green), 10-3 (dashed red) mol kg-1, when a(Cl-) = 0.5 mol kg-1.
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