Mass-dependent and mass-independent sulfur isotope fractionation (δ34S and δ33S) from Brazilian Archean and Proterozoic sulfide deposits by laser ablation multi-collector ICP-MS

Mass-independent sulfur isotope fractionation (MIF) has been observed in rocks of the geological record older than about 2.45 Ga, a characteristic which is thought to be related to processes in the Neoarchean atmosphere. Samples recording a MIF effect therefore have to contain sulfur of the exogenic sulfur cycle, while endogenic sulfur should not show this effect. The sulfides analysed from six Brazilian deposits represent either exogenic or...