The Shuram excursion, or Shuram-Wonoka excursion, is a change in δ13C, or in the ratio of carbon-13 to carbon-12, taking place between around 573 and 562 million years ago, during the Ediacaran Period.[1] It was first noticed in the Wonoka Formation in South Australia in 1990 and later in the Shuram Formation in Oman in 1993.[2] It is the largest negative δ13C excursion in Earth history, and recovery took 50 million years,[3] although the apparent magnitude of the excursion may be distorted due to meteoric water diagenesis.[4]

It is not known what caused the excursion.[5] The Shuram excursion may have played a role in sparking the rise of animals that resulted later in the Cambrian explosion.[6] The oxygen-consuming Ediacara biota experienced a radiation during the isotopic excursion as a response to the transient surplus of oxidants.[7] Microbial blooms of oxygenic phototrophs regulated the recovery of the carbon cycle from the isotopic excursion.[8]

References

  1. ↑ Canfield, Donald Eugene; Knoll, Andrew H.; Poulton, Simon W.; Narbonne, Guy M.; Dunning, Gregory R. (February 2020). "Carbon isotopes in clastic rocks and the Neoproterozoic carbon cycle". American Journal of Science. 320 (2): 97–124. Bibcode:2020AmJS..320...97C. doi:10.2475/02.2020.01. S2CID 214806821. Retrieved 12 March 2023.
  2. ↑ George Williams and Phillip Schmidt (March 2018). "Shuram–Wonoka carbon isotope excursion: Ediacaran revolution in the world ocean's meridional overturning circulation". Geoscience Frontiers. 9 (2): 391–402. Bibcode:2018GeoFr...9..391W. doi:10.1016/j.gsf.2017.11.006.
  3. ↑ Erwan Le Guerroué; et al. (20 April 2006). "Chemostratigraphic and sedimentological framework of the largest negative carbon isotopic excursion in Earth history: The Neoproterozoic Shuram Formation (Nafun Group, Oman)". Precambrian Research. 146 (1–2): 68–92. Bibcode:2006PreR..146...68L. doi:10.1016/j.precamres.2006.01.007. Retrieved 12 March 2023.
  4. ↑ Cui, Huan (15 September 2022). "Ediacaran Shuram Excursion interpreted, reinterpreted, and misinterpreted: A comment". Precambrian Research. 380: 106826. doi:10.1016/j.precamres.2022.106826. Retrieved 18 December 2023 – via Elsevier Science Direct.
  5. ↑ Wei, Guang-Yi; Wang, Jiuyuan; Planavsky, Noah J.; Zhao, Mingyu; Bolton, Edward W.; Jiang, Lei; Asael, Dan; Wei, Wei; Ling, Hong-Fei (1 July 2022). "On the origin of Shuram carbon isotope excursion in South China and its implication for Ediacaran atmospheric oxygen levels". Precambrian Research. 375: 106673. Bibcode:2022PreR..375j6673W. doi:10.1016/j.precamres.2022.106673. S2CID 248115031. Retrieved 17 December 2022.
  6. ↑ Colin Barras (Nov 9, 2019). "The weird creatures that might be the very first complex animals". New Scientist.
  7. ↑ Shields, Graham A.; Mills, Benjamin J. W.; Zhu, Maoyan; Raub, Timothy D.; Daines, Stuart J.; Lenton, Timothy M. (2 September 2019). "Unique Neoproterozoic carbon isotope excursions sustained by coupled evaporite dissolution and pyrite burial". Nature Geoscience. 12 (10): 823–827. Bibcode:2019NatGe..12..823S. doi:10.1038/s41561-019-0434-3. hdl:10871/39006. S2CID 201827639. Retrieved 12 January 2023.
  8. ↑ Cañadas, Fuencisla; Papineau, Dominic; Leng, Melanie J.; Li, Chao (10 January 2022). "Extensive primary production promoted the recovery of the Ediacaran Shuram excursion". Nature Communications. 13 (1): 148. Bibcode:2022NatCo..13..148C. doi:10.1038/s41467-021-27812-5. PMC 8748710. PMID 35013337.
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