Transient ocean oxygenation at end-Permian mass extinction onset shown by thallium isotopes
Newby, S.M.; Owens, J.D.; Schoepfer, S.D.; Algeo, T.J. (2021). Transient ocean oxygenation at end-Permian mass extinction onset shown by thallium isotopes. Nature Geoscience 14(9): 678-683. https://dx.doi.org/10.1038/s41561-021-00802-4
In: Nature Geoscience. Nature Publishing Group: London. ISSN 1752-0894; e-ISSN 1752-0908, more
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| Authors | | Top |
- Newby, S.M.
- Owens, J.D.
- Schoepfer, S.D.
- Algeo, T.J.
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| Abstract |
The end-Permian mass extinction (EPME) represents the largest biocrisis in Earth’s history, a result of environmental perturbations following volatiles released during Siberian Traps magmatism. A leading hypothesis links the marine mass extinction to the expansion of oceanic anoxia, although uncertainties exist as to the timing and extent. Thallium isotopes, a novel palaeoredox proxy with a rapid global response due to its short residence time in seawater, track global rates of manganese oxide burial, one of the first redox half-reactions to occur under reduced oxygen conditions. For this study, we analysed thallium isotopes from three widely distributed sites in Panthalassa, the largest ocean basin at the time. Our results provide evidence for the onset of deoxygenation considerably before the EPME, earlier by ≥1 Myr than the onset implied by other proxy records. Notably, there is a transient negative thallium isotope excursion concurrent with the EPME, which requires substantial manganese oxide burial based on the thallium isotope mass balance. This feature suggests a brief oxygenation episode before a return to more anoxic conditions, implying a more complex redox scenario, with rapid changes in oceanic (de)oxygenation leading to spatially and temporally variable biotic stresses. This oxygenation event may have been related to a transient cooling episode, based on published oxygen isotope records. These findings show that the Earth system experienced a highly fluctuating response to forcings linked to volcanogenic volatiles during the EPME. |
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