Fig. 2From: Weak hydrothermal carbonation of the Ongeluk volcanics: evidence for low CO2 concentrations in seawater and atmosphere during the Paleoproterozoic global glaciationStratigraphy of the Transvaal Supergroup in the Griqualand West region, South Africa. The relationship among the Ongeluk Formation, the Makganyene diamictite, and the overlying Hotazel Formation are shown (after Kirschvink et al. 2000). The Ongeluk Formation (~ 500–1000 m thick) conformably overlies the Makganyene Diamictite (~ 3–70 m thick) and underlies a dropstone layer at the bottom of the Hotazel Formation (~ 100–250 m thick) (Hoffman 2013)Back to article page