The first data on mass-independent fractionation of sulfur isotopes in sulfides from rocks of the eastern part of the Fennoscandian Shield

The first data on the multi-isotope composition of sulfur ( 32 S, 33 S, 34 S) in samples from the Fennoscandian Shield were obtained by the laser local method. An anomalous concentration of the stable isotope 33 S was registered in some samples. Δ 33 S ranges from–0.45 to +0.24‰, which indicates the mass-independent fractionation of S isotopes and provides evidence for the processes of primarily sedimentary accumulation of sulfides in the Archean oxygen-free atmosphere.