Abstract
Iron(Fe)-water reactions in a magma ocean can influence water storage and density of planets. These reactions can form Fe-O-H phases, whose density, melting, and electronic properties at planetary interior conditions are important for informing planetary models. Here, we study natural goethite (α-FeOOH) that is shock-compressed along its principal Hugoniot. Analysis of our velocity interferometer system for any reflector (VISAR) results extends the equation of state to over 800 GPa. X-ray diffraction and VISAR reflectivity results indicate the onset of melting occurs at ~95 GPa with complete melting by 166 GPa, which may be relevant to low seismic velocity anomalies observed above the core-mantle boundary. Analysis of X-ray emission spectroscopy results up to 285 …
Abstract
Iron(Fe)-water reactions in a magma ocean can influence water storage and density of planets. These reactions can form Fe-O-H phases, whose density, melting, and electronic properties at planetary interior conditions are important for informing planetary models. Here, we study natural goethite (α-FeOOH) that is shock-compressed along its principal Hugoniot. Analysis of our velocity interferometer system for any reflector (VISAR) results extends the equation of state to over 800 GPa. X-ray diffraction and VISAR reflectivity results indicate the onset of melting occurs at ~95 GPa with complete melting by 166 GPa, which may be relevant to low seismic velocity anomalies observed above the core-mantle boundary. Analysis of X-ray emission spectroscopy results up to 285 GPa shows the spin crossover of Fe, with dominantly low spin Fe above ~265 GPa in the melt, supporting formation of dense basal magma oceans in terrestrial planets. Using our measured FeOOH densities, we model planetary interiors up to 10 Earth masses. Assuming FeOOH forms via iron-water reactions, the radius decreases by up to 28%, while the density increases by up to 165% compared to the unreacted case, providing an avenue to investigate water storage and evolution in super-Earths and sub-Neptunes.
Data availability
The experimental results are provided in tables in the Supplementary Information. The raw data can be provided upon reasonable request.
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Acknowledgements
The authors thank Minkyung Han (Stanford), Claudia Parisuana (Stanford and SLAC), and Tommaso Vinci (LULI, Ecole Polytechnique) for their experimental assistance or technical support. Y.Z. thanks Dr. Bo Gan (Sichuan University) for discussions on data analysis. The MEC instrument of LCLS was supported by the US Department of Energy (DOE) Office of Science, Fusion Energy Science under contracts SF00515 and FWP100182. Y.Z., A.E.G., W.L.M., X.W., and D.S. acknowledge support from the NSF CSEDI Program (EAR2153968) and NASA Exoplanet Program (80NSSC23K0265). C.D. acknowledges support from the Swiss National Science Foundation under grant TMSGI2_211313. This work has been carried out within the framework of the NCCR PlanetS supported by the Swiss National Science Foundation under grant 51NF40_205606. A.E.G. acknowledges support from DOE 2019 ECA. The authors thank the Sorbonne University Mineral Collection for the loan of samples. E.B. acknowledges support from the French National Research Agency (ANR) grant no. ANR-22-CE49-0005. G.M., A.R., and L.L. would like to thank the support of the CNRS travel grant GoToXFEL and the ANR grant MinDIXI (ANR-22-CE49-0006). This research was supported by the French National Research Agency (ANR) and the Deutsche Forschungsgemeinschaft (DFG) through the projects PROPICE (grant No. ANR 22-CE92-0031 and DFG Project No. 505630685) (A.R.).
Author information
Author notes
These authors contributed equally: Komal Bali, Caroline Dorn, Hong Yang, Silvia Pandolfi, Amanda J. Chen, Xuehui Wei, Lélia Libon.
Authors and Affiliations
Earth and Planetary Sciences, Stanford University, Stanford, CA, USA
Yanyao Zhang, Hong Yang, Amanda J. Chen, Arianna E. Gleason & Wendy L. Mao 1.
Institute for Particle Physics and Astrophysics, ETH Zürich, Zürich, Switzerland
Komal Bali & Caroline Dorn 1.
Laboratoire LULI, CNRS - École Polytechnique - CEA - Sorbonne Université, Palaiseau Cedex, France
Alessandra Ravasio & Alessandra Benuzzi-Mounaix 1.
Sorbonne Université, Muséum National dʼHistoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Paris, France
Silvia Pandolfi, Lélia Libon, Eglantine Boulard & Guillaume Morard 1.
School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
Xuehui Wei & Sang Heon Shim 1.
ISTerre, Université Grenoble Alpes, CNRS, Grenoble, France
Lélia Libon & Guillaume Morard 1.
SLAC National Accelerator Laboratory, Menlo Park, CA, USA
Qijun Che, Hae Ja Lee, Eric Galtier, Nicholas A. Czapla, Dimosthenis Sokaras, Roberto Alonso-Mori, Arianna E. Gleason & Wendy L. Mao 1.
Department of Geosciences, Princeton University, Princeton, NJ, USA
Donghao Zheng
Authors
- Yanyao Zhang
- Komal Bali
- Caroline Dorn
- Alessandra Ravasio
- Hong Yang
- Silvia Pandolfi
- Amanda J. Chen
- Xuehui Wei
- Lélia Libon
- Qijun Che
- Donghao Zheng
- Eglantine Boulard
- Alessandra Benuzzi-Mounaix
- Hae Ja Lee
- Eric Galtier
- Nicholas A. Czapla
- Dimosthenis Sokaras
- Roberto Alonso-Mori
- Arianna E. Gleason
- Sang Heon Shim
- Guillaume Morard
- Wendy L. Mao
Contributions
Y.Z., R.A-M., A.E.G., S.H.S., G.M., and W.L.M initiate the project. Y.Z., A.R., H.Y., S.P., A.J.C., X.W., L.L., E.B., A.B.-M., H.J.L., E.G., N.A.C., R.A.-M., A.E.G, S.H.S, G.M, and W.L.M perform experiments. Y.Z., A.R., H.Y., S.P., X.W., D.Z., and E.B. perform data analysis and interpretation. K.B. and C.D. develop models. Q.C. performs computations. Y.Z., K.B., C.D., and W.L.M contribute to the initial draft of the paper. C.D., D.S., R.A.-M., A.E.G., S.H.S, G.M., and W.L.M supervise the group. All authors review and/or edit the manuscript.
Corresponding authors
Correspondence to Yanyao Zhang, Caroline Dorn, Roberto Alonso-Mori, Arianna E. Gleason, Sang Heon Shim, Guillaume Morard or Wendy L. Mao.
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Zhang, Y., Bali, K., Dorn, C. et al. Shock compression of FeOOH and implications for iron-water interactions in super-earth magma oceans. Nat Commun (2025). https://doi.org/10.1038/s41467-025-67845-8
Received: 28 June 2025
Accepted: 10 December 2025
Published: 27 December 2025
DOI: https://doi.org/10.1038/s41467-025-67845-8