Fig. 4.

δ³⁴S and Δ³³S profiles of sulphides in drill core T3 and associated δ³⁴S-Δ³³S and Δ³³S-Δ³⁶S compositional diagrams. Red dots, bulk analysis; white dots, mean value of in situ analysis for each sample; grey dots, individual spot analysis using the SHRIMP-SI (error bars are standard deviation of 1σ, see Methods). The grey shaded areas in the δ³⁴S and Δ³³S profiles represent the range of individual spot analysis for each sample. ARA, Archaean Reference Array, MDF, mass-dependent fractionation of sulphur isotopes, KFm, quartzite of the Koolbye Formation. The stratigraphic column below 145 m depth corresponds to the domain (ii) discussed in the text and shown in Fig. 2