Marine redox fluctuation as a potential trigger for the Cambrian explosion

The diversification of metazoans during the latest Neoproterozoic and early Cambrian has been attributed to, among other factors, a progressive rise in surface oxygen levels. However, recent results have also questioned the idea of a prominent rise in atmospheric oxygen levels or a major or unidirec...

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Bibliographic Details
Published in:Geology (Boulder) 2018-07, Vol.46 (7), p.587-590
Main Authors: Wei Guangyi, Wei Guangyi, Planavsky, Noah J, Tarhan, Lidya G, Chen Xi, Chen Xi, Wei Wei, Wei Wei, Li Da, Li Da, Ling Hongfei, Ling Hongfei
Format: Article
Language:English
Subjects:
actinides
adaptive radiation
Anoxia
Asia
Atmospheric oxygen
biodiversity
biologic evolution
biostratigraphy
C-13/C-12
Cambrian
carbon
carbonate rocks
Carbonates
case studies
chemostratigraphy
China
depositional environment
Ecological effects
Ecosystems
Ediacaran
Environmental conditions
Evolution
Explosions
Far East
Geology
Hubei China
isotope ratios
Isotopes
Landscape
Lower Cambrian
marine environment
mass balance
metals
Neoproterozoic
Oxidoreductions
Oxygen
Oxygenation
paleo-oceanography
paleoecology
paleoenvironment
Paleozoic
Phanerozoic
Precambrian
Proterozoic
radioactive isotopes
sea water
sedimentary rocks
shelf environment
stable isotopes
Stratigraphy
U-238/U-235
upper Precambrian
Uranium
Uranium isotopes
Variation
Yunnan China
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Summary:The diversification of metazoans during the latest Neoproterozoic and early Cambrian has been attributed to, among other factors, a progressive rise in surface oxygen levels. However, recent results have also questioned the idea of a prominent rise in atmospheric oxygen levels or a major or unidirectional shift in the marine redox landscape across this interval. Here, we present new carbonate-associated uranium isotope data from upper Ediacaran to lower Cambrian marine carbonate successions. These data provide evidence for short-lived episodes of widespread marine anoxia near the Ediacaran-Cambrian transition and during Cambrian Age 2 (ca. 525 Ma). We suggest that biotic turnover and resulting ecological restructuring, triggered by marine redox fluctuations rather than progressive oxygenation, were the dominant drivers of the Cambrian explosion. Episodes of harsh environmental conditions against a backdrop of Proterozoic-Phanerozoic oceanic oxygenation on the eve of the Cambrian explosion could have, by promoting ecosystem restructuring, spurred the diversification of the Cambrian Evolutionary Fauna.
ISSN:0091-7613
1943-2682
DOI:10.1130/G40150.1