Fig. 4. Temporal evolution of the early Palaeoproterozoic Earth.

Key features include the Yarrabubba and other impact events, the Great Oxidation Event (2.06–2.45 Ga) and glaciations (2.23–2.54 Ga). Glacial deposition age constraints from ref. ³⁸, the global δ¹³C trend of carbonates is modified from ref. ⁵¹, and the lull in magmatic activity is modified from ref. ⁴⁴. Note the close association of the Yarrabubba impact event to the end of the final Palaeoproterozoic glaciation, the Rietfontein, at 2225 ± 3 Ma and followed by the large positive δ¹³C excursion known as the Lomagundi event^82,83. Other impacts include the 2.02 Ga Vredefort Dome⁸, and the 2.49 Ga correlated Kuruman spherule layer in the Griqualand West basin of South Africa and the Dales Gorge spherule layer of the Hamersley basin in Western Australia⁷.