Editors
Paul F. Hoffman
Document Type
Article
Publication Date
12-17-2019
Publication Title
Proceedings of the National Academy of Sciences of the United States of America
Volume
116
Issue
51
First page number:
25478
Last page number:
25483
Abstract
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 that the outwash of subglacial meltwater supplied oxygen to the synglacial oceans, creating glaciomarine oxygen oases. The confluence of oxygen-rich meltwater and iron-rich seawater may have provided sufficient energy to sustain chemosynthetic communities. These processes could have supplied the requisite oxygen and organic carbon source for the survival of early animals and other eukaryotic heterotrophs through these extreme glaciations.
Keywords
Oxygenation; Glaciation; Snowball Earth; Iron formation; Fe isotopes
Disciplines
Earth Sciences | Physical Sciences and Mathematics
File Format
File Size
1.230 KB
Language
English
Repository Citation
Lechte, M. A.,
Wallace, M. W.,
van Smeerdijk Hooda, A.,
Li, W.,
Jiang, G.,
Halverson, G. P.,
Asael, D.,
McColl, S. L.,
Planavsky, N. J.
(2019).
Subglacial Meltwater Supported Aerobic Marine Habitats During Snowball Earth. In Paul F. Hoffman,
Proceedings of the National Academy of Sciences of the United States of America, 116(51),
25478-25483.
http://dx.doi.org/10.1073/pnas.1909165116