Transient fertilization of a post-Sturtian Snowball ocean margin with dissolved phosphate by clay minerals

Marine sedimentary rocks deposited across the Neoproterozoic Cryogenian Snowball interval, ~720–635 million years ago, suggest that post-Snowball fertilization of shallow continental margin seawater with phosphorus accelerated marine primary productivity, ocean-atmosphere oxygenation, and ultimately the rise of animals. However, the mechanisms that sourced and delivered bioavailable phosphate from land to the ocean are not fully understood. Here we demonstrate a causal relationship between clay mineral production by the melting Sturtian Snowball ice sheets and a short-lived increase in seawater phosphate bioavailability by at least 20-fold and oxygenation of an immediate post-Sturtian Snowball ocean margin. Bulk primary sediment inputs and inferred dissolved seawater phosphate dynamics point to a relatively low marine phosphate inventory that limited marine primary productivity and seawater oxygenation before the Sturtian glaciation, and again in the later stages of the succeeding interglacial greenhouse interval.

Ernest Chi Fru, Jalila Al Bahri, Christophe Brosson, Olabode Bankole, Jérémie Aubineau, Abderrazzak El Albani, Alexandra Nederbragt, Anthony Oldroyd, Alasdair Skelton, Linda Lowhagen, David Webster, Wilson Y. Fantong, Benjamin J. W. Mills, Lewis J. Alcott, Kurt O. Konhauser, Timothy W. Lyons