Early precipitated micropyrite in microbialites: a time capsule of microbial sulfur cycling. - Tout INSP Accéder directement au contenu
Article Dans Une Revue Geochemical Perspectives Letters Année : 2022

Early precipitated micropyrite in microbialites: a time capsule of microbial sulfur cycling.

Anthony Bouton
Nicolas Olivier
Emmanuelle Vennin

Résumé

Microbialites are organosedimentary rocks that have occurred throughout the Earth’s history. The relationships between diverse microbial metabolic activities and isotopic signatures in biominerals forming within these microbialites are key to understanding modern biogeochemical cycles, but also for accurate interpretation of the geologic record. Here, we performed detailed mineralogical investigations coupled with NanoSIMS (Nanoscale Secondary Ion Mass Spectrometry) analyses of pyrite S isotopes in mineralising microbial mats from two different environments, a hypersaline lagoon (Cayo Coco, Cuba) and a volcanic alkaline crater lake (Atexcac, Mexico). Both microbialite samples contain two distinct pyrite morphologies: framboids and euhedral micropyrites, which display distinct ranges of δ34S values1. Considering the sulfate-sulfur isotopic compositions associated with both environments, micropyrites display a remarkably narrow range of Δpyr (i.e. Δpyr ≡ δ34SSO4 − δ34Spyr) between 56 and 62 ‰. These measured Δpyr values agree with sulfate-sulfide equilibrium fractionation, as observed in natural settings characterised by low microbial sulfate reduction respiration rates. Moreover, the distribution of S isotope compositions recorded in the studied micropyrites suggests that sulfide oxidation also occurred at the microbialite scale. These results highlight the potential of micropyrites to capture signatures of microbial sulfur cycling and show that S isotope composition in pyrites record primarily the local micro-environments induced by the microbialite.

Domaines

Géochimie
Fichier principal
Vignette du fichier
GPL2209_noSI.pdf (15.33 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-03655569 , version 1 (02-05-2022)

Licence

Paternité - Pas d'utilisation commerciale - Pas de modification

Identifiants

Citer

Johanna Marin-Carbonne, M.-N. Decraene, Robin Havas, L. Remusat, V. Pasquier, et al.. Early precipitated micropyrite in microbialites: a time capsule of microbial sulfur cycling.. Geochemical Perspectives Letters, 2022, 21, pp.7-12. ⟨10.7185/geochemlet.2209⟩. ⟨hal-03655569⟩
357 Consultations
67 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More