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Did the Proterozoic ‘Canfield Ocean’ cause a laughing gas greenhouse?

Did the Proterozoic ‘Canfield Ocean’ cause a laughing gas greenhouse? ‘There's not a sea the passenger e’er pukes in, Turns up more dangerous breakers than the Euxine.’ (Byron, Don Juan , V. 5) Though expressed in one of his less noble couplets, Lord Byron's poor opinion of stinking sulfurous seas is probably widely shared. Not so, however, among early Earth geobiologists. Indeed, one of the most stimulating hypotheses about the ancient environment propounded in recent years has been that of the ‘Canfield Ocean’ ( Canfield, 1998 ). The idea is that with the advent of widespread microbial dissimilatory sulfate reduction under a moderately oxygenated atmosphere during the mid‐Proterozoic (roughly 1.85–0.8 Ga), the ocean would have become chemically stratified and euxinic. In other words, it resembled the modern Black Sea with an oxygenated, sulfate‐rich upper layer but with anoxic sulfidic deep waters. Prior to ~2.4 Ga, very low atmospheric oxygen levels would have kept marine sulfate concentrations extremely low, thus inhibiting microbial sulfate reduction and leading to anoxic iron‐rich oceans, though perhaps with oxygenated oases in the upper parts where oxygenic photosynthesis occurred. Between 2.4–1.85 Ga, the supply of sulfate gradually increased due to oxidative weathering of terrigenous sulfide minerals. At around 1.85 Ga, the dissolved sulfate supply, and http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Geobiology Wiley

Did the Proterozoic ‘Canfield Ocean’ cause a laughing gas greenhouse?

BUICK, R.
Geobiology , Volume 5 (2) – Jun 1, 2007
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References (24)

Publisher
Wiley
Copyright
Copyright © 2007 Wiley Subscription Services, Inc., A Wiley Company
ISSN
1472-4677
eISSN
1472-4669
DOI
10.1111/j.1472-4669.2007.00110.x
Publisher site
See Article on Publisher Site

Abstract

‘There's not a sea the passenger e’er pukes in, Turns up more dangerous breakers than the Euxine.’ (Byron, Don Juan , V. 5) Though expressed in one of his less noble couplets, Lord Byron's poor opinion of stinking sulfurous seas is probably widely shared. Not so, however, among early Earth geobiologists. Indeed, one of the most stimulating hypotheses about the ancient environment propounded in recent years has been that of the ‘Canfield Ocean’ ( Canfield, 1998 ). The idea is that with the advent of widespread microbial dissimilatory sulfate reduction under a moderately oxygenated atmosphere during the mid‐Proterozoic (roughly 1.85–0.8 Ga), the ocean would have become chemically stratified and euxinic. In other words, it resembled the modern Black Sea with an oxygenated, sulfate‐rich upper layer but with anoxic sulfidic deep waters. Prior to ~2.4 Ga, very low atmospheric oxygen levels would have kept marine sulfate concentrations extremely low, thus inhibiting microbial sulfate reduction and leading to anoxic iron‐rich oceans, though perhaps with oxygenated oases in the upper parts where oxygenic photosynthesis occurred. Between 2.4–1.85 Ga, the supply of sulfate gradually increased due to oxidative weathering of terrigenous sulfide minerals. At around 1.85 Ga, the dissolved sulfate supply, and

Journal

Geobiology – Wiley

Published: Jun 1, 2007

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