Earliest laterites and possible evidence for terrestrial vegetation in the Early Proterozoic

Paleosols preserve information about the composition of the atmosphere and paleoclimatic conditions. Here we report the discovery of the first pisolitic laterites of Precambrian age. The laterites are immediately above the regional unconformity at the base of the Early Proterozoic Gamagara Formation in paleokarst depressions on the Campbellrand dolomite, Transvaal Supergroup, South Africa. The paleosol profiles are very well preserved and show zoning, relict soil textures, and chemical composition virtually identical to those of modern laterites. The pisolitic laterites provide not only evidence for a highly oxygenated atmosphere and possible hot and humid climatic conditions in Early Proterozoic time, but also indicate the presence of terrestrial life on the Kaapvaal craton ∼2.0-2.2 b.y. ago.