The Great Oxidation Event preceded a Paleoproterozoic "snowball Earth"

Abstract

The inability to resolve the exact temporal relationship between two pivotal events in Earth history, the Paleoproterozoic Great Oxidation Event (GOE) and the first "snowball Earth" global glaciation, has precluded assessing causality between changing atmospheric composition and ancient climate change. Here we present temporally resolved quadruple sulfur isotope measurements (δ³⁴S, ∆³³S, and ∆³⁶S) from the Paleoproterozoic Seidorechka and Polisarka Sedimentary Formations on the Fennoscandian Shield, northwest Russia, that address this issue. Sulfides in the former preserve evidence of mass-independent fractionation of sulfur isotopes (S-MIF) falling within uncertainty of the Archean reference array with a ∆³⁶S/∆³³S slope of -1.8 and have small negative ∆³³S values, whereas in the latter mass-dependent fractionation of sulfur isotopes (S-MDF) is evident, with a ∆³⁶S/∆³³S slope of -8.8. These trends, combined with geochronological constraints, place the S-MIF/S-MDF transition, the key indicator of the GOE, between 2,501.5 ± 1.7 Ma and 2,434 ± 6.6 Ma. These are the tightest temporal and stratigraphic constraints yet for the S-MIF/S-MDF transition and show that its timing in Fennoscandia is consistent with the S-MIF/S-MDF transition in North America and South Africa. Further, the glacigenic part of the Polisarka Formation occurs 60 m above the sedimentary succession containing S-MDF signals. Hence, our findings confirm unambiguously that the S-MIF/S-MDF transition preceded the Paleoproterozoic snowball Earth. Resolution of this temporal relationship constrains cause-and-effect drivers of Earth's oxygenation, specifically ruling out conceptual models in which global glaciation precedes or causes the evolution of oxygenic photosynthesis.

Keywords: Great Oxidation Event; mass independent fractionation; quadruple sulfur isotopes; snowball Earth.

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.

Fig. 2.

(A) Cross-plot of ∆³³S and ∆³⁶S values from both the Polisarka (squares) and Seidorechka (circles) successions with marker color as assigned in Fig. 1 and shown in the key. Slope values were calculated using linear regression. Error bars are as listed in SI Appendix, Tables S1 and S2. (B) Orthogonal regression plot of all facies from the Seidorechka Sedimentary Formation (gray circles) showing calculated ∆³⁶S/∆³³S slope (blue line) and 3σ confidence interval (shaded blue area). (C) Orthogonal regression plot of the Limestone member (Polisarka Sedimentary Formation; dark blue squares) showing calculated ∆³⁶S/∆³³S slope (gray line) and 3σ confidence interval (shaded blue area).

Fig. 3.

Cross-plot of ∆³³S and δ³⁴S values from both the Polisarka (red squares) and Seidorechka (blue circles) successions. Error bars displayed are as listed in SI Appendix, Tables S1 and S2.

Fig. 4.

Summary of the age constraints exerted on the timing of the S-MIF/S-MDF transition across Fennoscandia, South Africa, North America, and western Australia. Last known occurrences of S-MIF are shaded green and first known occurrences of S-MDF are shaded red, with intermediate faded shading between the two representing periods of nondeposition, undated strata, and strata with no multiple sulfur isotope record. The approximate position of the Makganyene snowball Earth deposit is shown as a blue band across the four cratons. The possible timing of the atmospheric S-MIF/S-MDF transition is shown as an orange band. Further details on age constraints, including references, are given in SI Appendix, Table S3.