On the coevolution of Ediacaran oceans and animals

*Département des Sciences de la Terre et de l'Atmosphère, Université du Québec, Montréal, QC, Canada H3C 3P8; and
^‡Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138

Contributed by Paul F. Hoffman, March 4, 2008 (sent for review December 3, 2007)

Abstract

Fe speciation and S-isotope of pyrite data from the terminal Proterozoic Sheepbed Formation in Canada and Doushantuo Formation in China reveal that ocean deep waters were anoxic after the global glaciations (snowball Earth) ending 635 million years ago, but that marine sulfate concentrations and inferentially atmospheric oxygen levels were higher than before the glaciations. This supports a long-postulated link between oxygen levels and the emergence of eumetazoa. Subsequent ventilation of the deep ocean, inferred from shifts in Fe speciation in Newfoundland (previously published data) and western Canada (this report), paved the way for Ediacaran macrobiota to colonize the deep seafloors.

Footnotes

^†To whom correspondence may be addressed. E-mail: shen.yanan{at}uqam.ca or hoffman{at}eps.harvard.edu
Author contributions: Y.S. and P.F.H. designed research; Y.S., T.Z., and P.F.H. performed research; Y.S. analyzed data; and Y.S. and P.F.H. wrote the paper.
The authors declare no conflict of interest.
Freely available online through the PNAS open access option.