Subglacial meltwater supported aerobic marine habitats during Snowball Earth
Maxwell A Lechte, Malcolm W Wallace, Ashleigh van Smeerdijk Hood, Weiqiang Li, Ganqing Jiang, Galen P Halverson, Dan Asael, Stephanie L McColl, Noah J Planavsky
Proceedings of the National Academy of Sciences of the United States of America | NATL ACAD SCIENCES | Published : 2019
The Earth's most severe ice ages interrupted a crucial interval in eukaryotic evolution with widespread ice coverage during the Cryogenian Period (720 to 635 Ma). Aerobic eukaryotes must have survived the "Snowball Earth" glaciations, requiring the persistence of oxygenated marine habitats, yet evidence for these environments is lacking. We examine iron formations within globally distributed Cryogenian glacial successions to reconstruct the redox state of the synglacial oceans. Iron isotope ratios and cerium anomalies from a range of glaciomarine environments reveal pervasive anoxia in the ice-covered oceans but increasing oxidation with proximity to the ice shelf grounding line. We propose ..View full abstract
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Awarded by Australian Research Council
Awarded by NASA Astrobiology Institute
We thank A. Greig, P. Schreck, G. Hutchinson, and B. O'Connell for laboratory assistance; A. Shuster for field assistance; and A. Prave, D. Le Heron, and K. Hoffmann for locality advice. This work was supported by funding from the Australian Government Research Training Program Scholarship and Albert Shimmins Award to M.A.L.; Australian Research Council Discovery Grant DP130102240 to M.W.W.; and NASA Astrobiology Postdoctoral Fellowship, Puzey Fellowship, and Australian Research Council Discovery Early Career Researcher Award (DE190100988) to A.v.S.H. N.J.P. acknowledges support from the NASA Astrobiology Institute under Cooperative Agreement NNA15BB03A, issued through the Science Mission Directorate. We thank the handling editor and 2 reviewers for their constructive feedback.