Subduction-related oxidation of the sublithospheric mantle evidenced by ferropericlase and magnesiowüstite diamond inclusions

Ekaterina S Kiseeva; Nester Korolev; Iuliia Koemets; Dmitry A Zedgenizov; Richard Unitt; Catherine McCammon; Alena Aslandukova; Saiana Khandarkhaeva; Timofey Fedotenko; Konstantin Glazyrin; Dimitrios Bessas; Georgios Aprilis; Alexandr I Chumakov; Hiroyuki Kagi; Leonid Dubrovinsky

doi:10.1038/s41467-022-35110-x

Subduction-related oxidation of the sublithospheric mantle evidenced by ferropericlase and magnesiowüstite diamond inclusions

Nat Commun. 2022 Dec 6;13(1):7517. doi: 10.1038/s41467-022-35110-x.

Authors

Ekaterina S Kiseeva¹, Nester Korolev², Iuliia Koemets³, Dmitry A Zedgenizov^{4

5}, Richard Unitt⁶, Catherine McCammon³, Alena Aslandukova³, Saiana Khandarkhaeva³, Timofey Fedotenko^{7

8}, Konstantin Glazyrin⁸, Dimitrios Bessas⁹, Georgios Aprilis⁹, Alexandr I Chumakov⁹, Hiroyuki Kagi¹⁰, Leonid Dubrovinsky³

Affiliations

¹ School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland. kate.kiseeva@ucc.ie.
² Institute of Precambrian Geology and Geochronology of the Russian Academy of Sciences, nab. Makarova 2, St. Petersburg, 199034, Russia.
³ Bayerisches Geoinstitut, Universität Bayreuth, D-95440, Bayreuth, Germany.
⁴ A.N. Zavaritsky Institute of Geology and Geochemistry, 15 Vonsovskogo street, Ekaterinburg, 620016, Russia.
⁵ Ural State Mining University, 30 Kuibysheva street, Ekaterinburg, 620014, Russia.
⁶ School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland.
⁷ Materials Physics and Technology at Extreme Conditions, Laboratory of Crystallography, Universität Bayreuth, D-95440, Bayreuth, Germany.
⁸ Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany.
⁹ ESRF-The European Synchrotron, CS 40220, 38043, Grenoble, Cedex 9, France.
¹⁰ Geochemical Research Center, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan.

Abstract

Ferropericlase (Mg,Fe)O is the second most abundant mineral in Earth's lower mantle and a common inclusion found in subcratonic diamonds. Pyrolitic mantle has Mg# (100 × Mg/(Mg+Fe)) ~89. However, ferropericlase inclusions in diamonds show a broad range of Mg# between 12 and 93. Here we use Synchrotron Mössbauer Source (SMS) spectroscopy and single-crystal X-ray diffraction to determine the iron oxidation state and structure of two magnesiowüstite and three ferropericlase inclusions in diamonds from São Luiz, Brazil. Inclusion Mg#s vary between 16.1 and 84.5. Ferropericlase inclusions contain no ferric iron within the detection limit of SMS, while both magnesiowüstite inclusions show the presence of monocrystalline magnesioferrite ((Mg,Fe)Fe³⁺₂O₄) with an estimated 47-53 wt% Fe₂O₃. We argue that the wide range of Fe concentrations observed in (Mg,Fe)O inclusions in diamonds and the appearance of magnesioferrite result from oxidation of ferropericlase triggered by the introduction of subducted material into sublithospheric mantle.

Grants and funding

21-55-50011/Russian Foundation for Basic Research (RFBR)