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Multiple S-isotopic evidence for episodic shoaling of anoxic water during Late Permian mass extinction.

Shen Y, Farquhar J, Zhang H, Masterson A, Zhang T, Wing BA - Nat Commun (2011)

Bottom Line: Global fossil data show that profound biodiversity loss preceded the final catastrophe that killed nearly 90% marine species on a global scale at the end of the Permian.We observe a sulphur isotope signal (negative δ(34)S with negative Δ(33)S) that may have resulted from limitation of sulphate supply, which may be linked to a near shutdown of bioturbation during shoaling of anoxic water.These results indicate that episodic shoaling of anoxic water may have contributed to the profound biodiversity crisis before the final catastrophe.

View Article: PubMed Central - PubMed

Affiliation: CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China. yashen@ustc.edu.cn

ABSTRACT
Global fossil data show that profound biodiversity loss preceded the final catastrophe that killed nearly 90% marine species on a global scale at the end of the Permian. Many hypotheses have been proposed to explain this extinction and yet still remain greatly debated. Here, we report analyses of all four sulphur isotopes ((32)S, (33)S, (34)S and (36)S) for pyrites in sedimentary rocks from the Meishan section in South China. We observe a sulphur isotope signal (negative δ(34)S with negative Δ(33)S) that may have resulted from limitation of sulphate supply, which may be linked to a near shutdown of bioturbation during shoaling of anoxic water. These results indicate that episodic shoaling of anoxic water may have contributed to the profound biodiversity crisis before the final catastrophe. Our data suggest a prolonged deterioration of oceanic environments during the Late Permian mass extinction.

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Related in: MedlinePlus

A cartoon representing the sulphur cycle associated with the shoaling deep anoxic water during the Latest Permian.(a) Sulphur cycle under typical steady-state conditions in which bioturbation aerates shallow sediments and promotes transport of sulphate into and out of the sediments. (b) Sulphur cycle associated with shoaling of deep anoxic water in which bioturbation shuts down, limiting transport of sulphate within sediments and exchange between sediment pore water sulphate and oceanic sulphate pools. High organic content in the sediments promotes nearly quantitative sulphate reduction, resulting in non-steady-state conditions and formation of pyrites with negative δ34S and negative Δ33S values as seen in Figures 1 and 2.
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f3: A cartoon representing the sulphur cycle associated with the shoaling deep anoxic water during the Latest Permian.(a) Sulphur cycle under typical steady-state conditions in which bioturbation aerates shallow sediments and promotes transport of sulphate into and out of the sediments. (b) Sulphur cycle associated with shoaling of deep anoxic water in which bioturbation shuts down, limiting transport of sulphate within sediments and exchange between sediment pore water sulphate and oceanic sulphate pools. High organic content in the sediments promotes nearly quantitative sulphate reduction, resulting in non-steady-state conditions and formation of pyrites with negative δ34S and negative Δ33S values as seen in Figures 1 and 2.

Mentions: The mixing of pyrite observed from Meishan may be indicative of shoaling of anoxic deep water before the end-Permian mass extinction in Beds 25–26. A cartoon that describes the principal features of this hypothesis is presented in Figure 3, and envisions a situation similar to that observed in the Black Sea where oxic waters overly but is separated from a deep water euxinic pool by Fe2+-rich non-sulphidic, anoxic waters (Fig. 3a). This scenario is based on deep-water column euxinia during the latest Permian that has been well documented25143536. When anoxic water shoal, the sulphur cycle within sediments, formerly in the oxic zone, will change from a system with effective transport of sulphate into and out of the sediment (Fig. 3b) to a system in which bioturbation does not play a significant role, and effective exchange of sulphate between the sediment porewater and the overlying water column would be suppressed.


Multiple S-isotopic evidence for episodic shoaling of anoxic water during Late Permian mass extinction.

Shen Y, Farquhar J, Zhang H, Masterson A, Zhang T, Wing BA - Nat Commun (2011)

A cartoon representing the sulphur cycle associated with the shoaling deep anoxic water during the Latest Permian.(a) Sulphur cycle under typical steady-state conditions in which bioturbation aerates shallow sediments and promotes transport of sulphate into and out of the sediments. (b) Sulphur cycle associated with shoaling of deep anoxic water in which bioturbation shuts down, limiting transport of sulphate within sediments and exchange between sediment pore water sulphate and oceanic sulphate pools. High organic content in the sediments promotes nearly quantitative sulphate reduction, resulting in non-steady-state conditions and formation of pyrites with negative δ34S and negative Δ33S values as seen in Figures 1 and 2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3105335&req=5

f3: A cartoon representing the sulphur cycle associated with the shoaling deep anoxic water during the Latest Permian.(a) Sulphur cycle under typical steady-state conditions in which bioturbation aerates shallow sediments and promotes transport of sulphate into and out of the sediments. (b) Sulphur cycle associated with shoaling of deep anoxic water in which bioturbation shuts down, limiting transport of sulphate within sediments and exchange between sediment pore water sulphate and oceanic sulphate pools. High organic content in the sediments promotes nearly quantitative sulphate reduction, resulting in non-steady-state conditions and formation of pyrites with negative δ34S and negative Δ33S values as seen in Figures 1 and 2.
Mentions: The mixing of pyrite observed from Meishan may be indicative of shoaling of anoxic deep water before the end-Permian mass extinction in Beds 25–26. A cartoon that describes the principal features of this hypothesis is presented in Figure 3, and envisions a situation similar to that observed in the Black Sea where oxic waters overly but is separated from a deep water euxinic pool by Fe2+-rich non-sulphidic, anoxic waters (Fig. 3a). This scenario is based on deep-water column euxinia during the latest Permian that has been well documented25143536. When anoxic water shoal, the sulphur cycle within sediments, formerly in the oxic zone, will change from a system with effective transport of sulphate into and out of the sediment (Fig. 3b) to a system in which bioturbation does not play a significant role, and effective exchange of sulphate between the sediment porewater and the overlying water column would be suppressed.

Bottom Line: Global fossil data show that profound biodiversity loss preceded the final catastrophe that killed nearly 90% marine species on a global scale at the end of the Permian.We observe a sulphur isotope signal (negative δ(34)S with negative Δ(33)S) that may have resulted from limitation of sulphate supply, which may be linked to a near shutdown of bioturbation during shoaling of anoxic water.These results indicate that episodic shoaling of anoxic water may have contributed to the profound biodiversity crisis before the final catastrophe.

View Article: PubMed Central - PubMed

Affiliation: CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China. yashen@ustc.edu.cn

ABSTRACT
Global fossil data show that profound biodiversity loss preceded the final catastrophe that killed nearly 90% marine species on a global scale at the end of the Permian. Many hypotheses have been proposed to explain this extinction and yet still remain greatly debated. Here, we report analyses of all four sulphur isotopes ((32)S, (33)S, (34)S and (36)S) for pyrites in sedimentary rocks from the Meishan section in South China. We observe a sulphur isotope signal (negative δ(34)S with negative Δ(33)S) that may have resulted from limitation of sulphate supply, which may be linked to a near shutdown of bioturbation during shoaling of anoxic water. These results indicate that episodic shoaling of anoxic water may have contributed to the profound biodiversity crisis before the final catastrophe. Our data suggest a prolonged deterioration of oceanic environments during the Late Permian mass extinction.

Show MeSH
Related in: MedlinePlus