Fig. 1.

Bulk rock-CRS ∆³³S, ∆³⁶S, and δ³⁴S measurements from the Seidorechka Sedimentary Formation (Lower) and Polisarka Sedimentary Formation (Upper). Core log summarized from previous studies (15, 17). Filled circle color corresponds to lithostratigraphic member: Seidorechka Sedimentary Formation: orange = Sandstone-Siltstone member, yellow = Quartzite member, brown = Limestone-Shale member, gray = Shale member; Polisarka Sedimentary Formation: dark blue = Limestone member, yellow = Diamictite-Greywacke member. Data point values and uncertainties are listed in SI Appendix, Tables S1 and S2; δ³⁴S error bars fall within the size of the symbol. Age dates that constrain the dataset are discussed in the text.