The link between water and ferric iron in Earth's lower mantle

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Authors

Johannes Buchen, Olivia S. Pardo, Vasilije V. Dobrosavljevic, Wolfgang Sturhahn, Takayuki Ishii, Stella Chariton, Eran Greenberg, Thomas S. Toellner, Jennifer M. Jackson

Abstract

As the most massive geochemical reservoir, the lower mantle affects Earth's budget of volatile elements, including hydrogen or H2O. The properties of minerals in Earth's lower mantle are further affected by changes in the electronic configurations of iron cations, i.e., spin transitions. Potential feedback between deep H2O retention and spin transitions in mantle minerals, however, remain unexplored. We constrained the excess energy arising from the spin transition of ferric iron in high-pressure oxyhydroxide phases by a combination of high-pressure experiments. Our results show that the spin transition of ferric iron may stabilize oxyhydroxide phases in the lower mantle even at low H2O concentrations. In addition, the spin transition expands the thermal stability of high-pressure oxyhydroxides and creates a geochemical link between H2O and ferric iron in Earth's lower mantle that might be sampled by rising plumes and reflected in related magmas produced at the surface.

DOI

https://doi.org/10.31223/X5W12K

Subjects

Earth Sciences, Geochemistry, Mineral Physics

Keywords

Earth's mante, spin transition, deep H2O cycle

Dates

Published: 2024-10-10 10:11

License

CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
Supplementary Tables S1 and S2 are available from the corresponding author upon request.