The emergence of the Ediacara biota soon after the Gaskiers glaciation ca. 580 million years ago (Ma) implies a possible glacial fuse for the evolution of animals. However, the timing of Ediacaran glaciation remains controversial because of poor age constraints on the ∼30 Ediacaran glacial deposits known worldwide. In addition, paleomagnetic constraints and a lack of convincing Snowball-like cap carbonates indicate that Ediacaran glaciations likely did not occur at low latitudes. Thus, reconciling the global occurrences without global glaciation remains a paradox. Here, we report that the large amplitude, globally synchronous ca. 571–562 Ma Shuram carbon isotope excursion occurs below the Ediacaran Hankalchough glacial deposit in Tarim, confirming a post-Shuram glaciation. Leveraging paleomagnetic evidence for a ∼90° reorientation of all continents due to true polar wander, and a non-Snowball condition that rules out low-latitude glaciations, we use paleogeographic reconstructions to further constrain glacial ages. Our results depict a ‘Great Ediacaran Glaciation’ occurring diachronously but continuously from ca. 580–560 Ma as different continents migrated through polar–temperate latitudes. The succession of radiation, turnover and extinction of the Ediacara biota strongly reflects glacial–deglacial dynamics.

Termination of the terminal Cryogenian Marinoan snowball Earth glaciation (~650–635 Ma) is associated with the worldwide deposition of a cap carbonate. Modeling studies suggest that, during and immediately following deglaciation, the ocean may have experienced a rapid rise in pH and physical stratification followed by oceanic overturn. Testing these predictions requires the establishment of a high-resolution sequence of events within sedimentary records. Here we report the conspicuous occurrence of pyrite concretions in the topmost Nantuo Formation (South China) that was deposited in the Marinoan glacial deposits. Sedimentary facies and sulfur isotope data indicate pyrite precipitation in the sediments with H₂S diffusing from the overlying sulfidic/euxinic seawater and Fe (II) from diamictite sediments. These observations suggest a transient but widespread presence of marine euxinia in an ocean characterized by redox stratification, high bioproductivity, and high-fluxes of sulfate from chemical weathering before the deposition of the cap carbonate.

Geological evidence indicates that the deglaciation of Marinoan snowball Earth ice age (~635 Myr ago) was associated with intense continental weathering, recovery of primary productivity, transient marine euxinia, and potentially extensive CH₄ emission. It is proposed that the deglacial CH₄ emissions may have provided positive feedbacks for ice melting and global warming. However, the origin of CH₄ remains unclear. Here we report Ni isotopes (δ⁶⁰Ni) and Yttrium-rare earth element (YREE) compositions of syndepositional pyrites from the upper most Nantuo Formation (equivalent deposits of the Marinoan glaciation), South China. The Nantuo pyrite displays anti-correlations between Ni concentration and δ⁶⁰Ni, and between Ni concentration and Sm/Yb ratio, suggesting mixing between Ni in seawater and Ni from methanogens. Our study indicates active methanogenesis during the termination of Marinoan snowball Earth. This suggests that methanogenesis was fueled by methyl sulfides produced in sulfidic seawater during the deglacial recovery of marine primary productivity.