{
  "abstract": "The Earth's mantle has elevated Fe 3+ relative to those of other rocky bodies, a property thought to reflect the disproportionation of ferrous iron into its metallic and ferric counterparts during core formation at elevated pressures. However, whether more massive planets ('super-Earths') become increasingly oxidised is poorly known for lack of constraints on the oxidation-and electronic state of iron at extreme pressures. We present in-situ energydomain synchrotron Mössbauer spectra of 57 Fe-enriched peridotitic-and basaltic glasses at 298 K compressed from 1 bar to 174 GPa in a diamond anvil cell. Three glasses were synthesised with different Fe 3+ /[Fe 3+ + Fe 2+ ] ratios; 0.02 ± 0.02 (Fe 2+ -basaltic, peridotitic) and 1.00 ± 0.02 (Fe 3+ -basaltic), respectively, as determined by colourimetry. While the spectrum of pure Fe 3+ -basaltic glass shows minimal changes in its hyperfine parameters up to 174 GPa, the spectra of Fe 2+ -peridotitic and basaltic glasses are fit by two doublets, D 1 and D 2 . At 1 bar, their relative intensities are ∼92 % and ∼8 %, respectively, but the integral area ratio, D 2 /(D 1 + D 2 ), reaches 0.65 by 172 GPa. Because this transition is reversible with pressure and no metallic iron is detected, the D 2 feature is ascribed to Fe 2+ in its low spin (LS) state, whereas D 1 is consistent with Fe 2+ high spin (HS). The Fe 3+ /[Fe 3+ +Fe 2+ ] of planetary mantles at constant relative f O 2 increases to a maximum near ∼40 GPa, before decreasing at higher pressures due to the stabilisation of Fe 2+ LS . This peak coincides with estimated coremantle equilibrium on Earth, implying that its uniquely oxidised mantle and habitable state may result from core formation within a Goldilocks pressure range. Secondary atmospheres are predicted to transition from H 2rich for Moon-sized bodies, to CO-rich for Earth-like planets and H 2 -and CH 4 -bearing around super-Earths and sub-Neptunes.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": null,
  "author_total": 8,
  "authors": [
    {
      "name": "Alice Girani"
    },
    {
      "name": "Sylvain Petitgirard"
    },
    {
      "name": "Sergey Yaroslavtsev"
    },
    {
      "name": "Georgios Aprilis"
    },
    {
      "name": "James Badro"
    },
    {
      "name": "Antoine Bézos"
    },
    {
      "name": "Hugh St. C. O’neill"
    },
    {
      "name": "Paolo A Sossi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7062t2t6azh3a.bib",
  "cited_by": 0,
  "doi": "10.1016/j.epsl.2026.120168",
  "fulltext_url": null,
  "id": "7062t2t6azh3a",
  "issns": [
    "0012-821X"
  ],
  "landing_url": "https://hal.science/hal-05740204v1",
  "language": "en",
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "hal",
      "0.sdu"
    ],
    [
      "hal",
      "1.sdu.stu"
    ],
    [
      "openalex",
      "1908|High-pressure geophysics and materials"
    ]
  ],
  "openalex": "W7164758043",
  "pdf_url": "https://hal.science/hal-05740204/document",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-15",
  "publisher": "Elsevier",
  "ris": "https://research.draconitic.com/paper/7062t2t6azh3a.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:29Z",
      "native_id": "hal-05740204",
      "source": "hal",
      "url": "https://hal.science/hal-05740204v1"
    }
  ],
  "subjects": [
    {
      "field": "earth",
      "origin": "openalex:1908|High-pressure geophysics and materials",
      "subfield": "geophysics"
    }
  ],
  "title": "Low-spin ferrous iron suppresses mantle oxidation beyond Earth-like pressures",
  "title_text": "Low-spin ferrous iron suppresses mantle oxidation beyond Earth-like pressures",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:17:29Z",
  "url": "https://research.draconitic.com/paper/7062t2t6azh3a",
  "venue": "Earth and Planetary Science Letters",
  "versions": []
}