In the carbonate rocks of the Kursk block of Sarmatia, evidence of global perturbations in the atmosphere and hydrosphere of the Earth has been recorded. Dolomites of the Rogovskaya Formation accumulated on the passive continental margin and are characterized by a chondrite Y/Ho ratio, the absence of Ce* anomalies, and δ¹³C and δ¹⁸O values typical of Neoarchean and Early Paleoproterozoic marine carbonates. Therefore, their accumulation took place before the GOE . Limestones of the Tim Formation are contrastingly distinguished by negative Ce* anomalies, superchondrite Y/Ho ratio, and anomalously high values of δ¹³C = 10.4 to 12.1 ‰ V-PDB. It follows from this that carbonates of the Tim Formation were formed after the GOE during the Yatuli-Lomagundi event. Their Pb-Pb age of 2233 ± 8 Ma is close to its lower boundary.