Trace element partitioning in sedimentary pyrite controlled by nanoscale processes
Year: 2026
Type: article
Abstract: The trace element (TE) composition of sedimentary pyrite is widely used as a palaeo-proxy for Earth environments, raising a need to better estimate the pyrite-water TE partitioning during sedimentary pyrite formation. By monitoring TE incorporation into pyrite grown in laboratory experiments at ambient temperature, we determined transfer functions that link the TE signature of early diagenetic pyrites formed under anoxic, Fe-rich conditions to the initial TE concentrations of the corresponding precipitating aqueous medium, relevant to sediment porewater. Synchrotron based X-ray fluorescence mapping at the nanometre scale and correlation plots reveal that TE association modes with pyrite progressively deviate from ideal solid solution from Se to Ni, As, and Co, while Cu and Zn display exsolution behaviour. Nanoscale distributions modulate the solid-solution distribution coefficients with a significant dependence on the total TE:Fe ratio of the pyrite precipitation medium. Hence, we provide revised average concentration factors and a ranking of distribution coefficients: Se > Co ≥ Cu ≥ Ni ≥ As ≥ Zn ≥ Mn. These improved estimates, particularly for Co, Mn and Zn partitioning in sedimentary pyrite, offer refined constraints for palaeoenvironmental reconstructions and Earth oxygenation studies.
Source: Geochemical Perspectives Letters
Institutions: Centre National de la Recherche Scientifique, Sorbonne Université, Institut de minéralogie, de physique des matériaux et de cosmochimie, Université Toulouse III - Paul Sabatier, Centre National d'Études Spatiales, Observatoire Midi-Pyrénées, Géosciences Environnement Toulouse, Institut de Recherche pour le Développement, Synchrotron SOLEIL
Language: English
Subfield: Paleontology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7166548584