Globally asynchronous sulphur isotope signals require re-definition of the Great Oxidation Event.

Pascal Philippot (1, 2) , Janaína N. Ávila (3) , Bryan A. Killingsworth (4) , Svetlana Tessalina (5) , Franck Baton (1) , Tom Caquineau (1) , Élodie Muller (1) , Ernesto Pecoits (1) , Pierre Cartigny (1) , Stefan Lalonde (4) , Trevor R. Ireland (3) , Christophe Thomazo (6) , Martin J. van Kranendonk (7) , Vincent Busigny (1)

1 IPGP - Institut de Physique du Globe de Paris
2 Géosciences Montpellier
3 RSES - Research School of Earth Sciences [ANU, Canberra]
4 LDO - Domaines Océaniques
5 John de Laeter Centre for Isotope Research
6 BGS - Biogéosciences [UMR 6282]
7 BEES - School of Biological, Earth and Environmental Sciences [Sydney]

The Great Oxidation Event (GOE) has been defined as the time interval when sufficient atmospheric oxygen accumulated to prevent the generation and preservation of mass-independent fractionation of sulphur isotopes (MIF-S) in sedimentary rocks. Existing correlations suggest that the GOE was rapid and globally synchronous. Here we apply sulphur isotope analysis of diagenetic sulphides combined with U-Pb and Re-Os geochronology to document the sulphur cycle evolution in Western Australia spanning the GOE. Our data indicate that, from ~2.45 Gyr to beyond 2.31 Gyr, MIF-S was preserved in sulphides punctuated by several episodes of MIF-S disappearance. These results establish the MIF-S record as asynchronous between South Africa, North America and Australia, argue for regional-scale modulation of MIF-S memory effects due to oxidative weathering after the onset of the GOE, and suggest that the current paradigm of placing the GOE at 2.33–2.32 Ga based on the last occurrence of MIF-S in South Africa should be re-evaluated.

Domaines: Géochimie

Pascal Philippot, Janaína N. Ávila, Bryan A. Killingsworth, Svetlana Tessalina, Franck Baton, et al.. Globally asynchronous sulphur isotope signals require re-definition of the Great Oxidation Event.. Nature Communications, 2018, 9 (1), pp.2245. ⟨10.1038/s41467-018-04621-x⟩. ⟨hal-01822553⟩