¹Tian Feng,^1,2Arthur Omran,¹Maheen Gull,³Micah J. Schaible,^3,4Thomas M. Orlando,¹Matthew A. Pasek
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.07.022]
¹School of Geosciences, University of South Florida, NES 204, 4202 East Fowler Ave., Tampa, FL 33620, USA
²Department of Chemistry, University of North Florida, Jacksonville, FL 32224, USA
³School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
⁴School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
Copyright Elsevier

Phosphorus is often present in meteorites as the mineral schreibersite, in which P is in a reduced oxidation state as a phosphide. Phosphides such as schreibersite have been proposed to be important to the development of life on the earth and may serve as indicators of metamorphic grade on meteorite parent bodies. Here we investigate how synthetic schreibersite (as the iron end-member, Fe3P) oxidizes into calcium phosphates through reaction with silicates under high temperature conditions, at specific oxygen fugacities, and in the absence of water. We find that schreibersite readily oxidizes to phosphates at temperatures of 750–850 °C over a few weeks depending on the oxygen fugacity of the environment. The rate of this process is best matched by diffusion-limited kinetics. Therefore, the metamorphic heating timescale required to equilibrate phosphorus in meteoritic samples with small schreibersite grains (∼1 μm), such as in the type 3 ordinary chondrites (3.0–3.3), was short (10–100 days).