Global marine redox changes drove the rise and fall of the Ediacara biota.

Autor: Zhang F; School of Earth Sciences and Engineering, Nanjing University, Nanjing, China.; Department of Geology and Geophysics, Yale University, New Haven, CT, USA.; The Globe Institute, University of Copenhagen, Copenhagen K, Denmark.; School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA., Xiao S; Department of Geosciences, Virginia Tech, Blacksburg, VA, USA., Romaniello SJ; School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA., Hardisty D; Department of Earth and Environmental Science, Michigan State University, East Lansing, MI, USA., Li C; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China., Melezhik V; Geological Survey of Norway, Trondheim, Norway., Pokrovsky B; Geological Institute, Russian Academy of Sciences, Moscow, Russia., Cheng M; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China., Shi W; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China., Lenton TM; Global Systems Institute, University of Exeter, Exeter, UK., Anbar AD; School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA.; School of Molecular Science, Arizona State University, Tempe, AZ, USA.
Jazyk: angličtina
Zdroj: Geobiology [Geobiology] 2019 Nov; Vol. 17 (6), pp. 594-610. Date of Electronic Publication: 2019 Jul 28.
DOI: 10.1111/gbi.12359
Abstrakt: The role of O 2 in the evolution of early animals, as represented by some members of the Ediacara biota, has been heavily debated because current geochemical evidence paints a conflicting picture regarding global marine O 2 levels during key intervals of the rise and fall of the Ediacara biota. Fossil evidence indicates that the diversification the Ediacara biota occurred during or shortly after the Ediacaran Shuram negative C-isotope Excursion (SE), which is often interpreted to reflect ocean oxygenation. However, there is conflicting evidence regarding ocean oxygen levels during the SE and the middle Ediacaran Period. To help resolve this debate, we examined U isotope variations (δ 238 U) in three carbonate sections from South China, Siberia, and USA that record the SE. The δ 238 U data from all three sections are in excellent agreement and reveal the largest positive shift in δ 238 U ever reported in the geologic record (from ~ -0.74‰ to ~ -0.26‰). Quantitative modeling of these data suggests that the global ocean switched from a largely anoxic state (26%-100% of the seafloor overlain by anoxic waters) to near-modern levels of ocean oxygenation during the SE. This episode of ocean oxygenation is broadly coincident with the rise of the Ediacara biota. Following this initial radiation, the Ediacara biota persisted until the terminal Ediacaran period, when recently published U isotope data indicate a return to more widespread ocean anoxia. Taken together, it appears that global marine redox changes drove the rise and fall of the Ediacara biota.
(© 2019 John Wiley & Sons Ltd.)
Databáze: MEDLINE
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