Langbahn Team – Weltmeisterschaft

Sturtian glaciation

The Sturtian glaciation was a worldwide glaciation during the Cryogenian Period when the Earth experienced repeated large-scale glaciations.[2][4] As of January 2023, the Sturtian glaciation is thought to have lasted from c. 717 Ma to c. 660 Ma, a time span of approximately 57 million years.[2] It is hypothesised to have been a Snowball Earth event, or contrastingly multiple regional glaciations, and is the longest and most severe known glacial event preserved in the geologic record after the much earlier Huronian glaciation.

Etymology of name

Ultimately, current usage of the term is in reference to the globally significant Sturt Formation (originally Sturtian Tillite)[5] within the Adelaide Superbasin of Australia. The Sturt Formation is named after Sturt Gorge, South Australia;[6][7] itself named after the Sturt River, which was given its name in April 1831 by British Military Officer Captain Collet Barker,[8] after fellow officer and explorer Charles Sturt.[9]

The Sturtian glaciation is an informal, but commonly used name for the older of two worldwide glacial events (the other is known as the Marinoan/Elatina glaciation) preserved in Cryogenian rocks.[6] The term Sturtian was originally defined[10] as a chronostratigraphic unit (Series) and later proposed as an international chronostratigraphic division;[11] however, this has been superseded by international nomenclature.[further explanation needed] The suggestion of the glacial nature of the Sturt Formation during the early 20th century resulted in discussion about Neoproterozoic glaciations (thought to be Cambrian at the time) and encouraged the research that eventually resulted in the Snowball Earth hypothesis.[6][12]

Geology

Rocks preserving evidence for the Sturtian Glaciation are found on every continent. Notable sections are found in Australia, Canada, China, Ethiopia, Namibia, Siberia, and Svalbard.

According to Eyles and Young, "Glaciogenic rocks figure prominently in the Neoproterozoic stratigraphy of southeastern Australia and the northern Canadian Cordillera. The Sturtian glaciogenic succession (c. 740 Ma) unconformably overlies rocks of the Burra Group." The Sturtian succession includes two major diamictite-mudstone sequences which represent glacial advance and retreat cycles. It is stratigraphically correlated with the Rapitan Group of North America.[13]

Reusch's Moraine in northern Norway may have been deposited during this period.[14]

In 2024 researchers at the University of Adelaide and University of Sydney, using a combination of known geological formations from the Cryogenian Period and plate tectonic modelling, using EarthByte computer models, proposed the low temperature was the result of low levels of CO2 degassing along mid-ocean ridges, the result of the break-up of the supercontinent Rodinia.[15]

The duration of the ice sheet advance at the start of the Sturtian glaciation lasted for less than a million years.[16]

Effects on life

In the aftermath of the Sturtian glaciation, biomarkers and body fossils indicate an increase in biological complexity.[17]

See also

References

  1. ^ a b Arnaud, Emmanuelle; Halverson, Galen P.; Shields-Zhou, Graham Anthony (30 November 2011). "Chapter 1: The geological record of Neoproterozoic ice ages". Geological Society, London, Memoirs. 36 (1): 1–16. doi:10.1144/M36.1.
  2. ^ a b c d Hoffman, Paul F.; Abbot, Dorian S.; Ashkenazy, Yosef; Benn, Douglas I.; Brocks, Jochen J.; Cohen, Phoebe A.; Cox, Grant M.; Creveling, Jessica R.; Donnadieu, Yannick; Erwin, Douglas H.; Fairchild, Ian J.; Ferreira, David; Goodman, Jason C.; Halverson, Galen P.; Jansen, Malte F. (2017-11-03). "Snowball Earth climate dynamics and Cryogenian geology-geobiology". Science Advances. 3 (11): e1600983. Bibcode:2017SciA....3E0983H. doi:10.1126/sciadv.1600983. ISSN 2375-2548. PMC 5677351. PMID 29134193.
  3. ^ Brocks, Jochen J. (2018-09-28). Lyons, Timothy W.; Droser, Mary L.; Lau, Kimberly V.; Porter, Susannah M. (eds.). "The transition from a cyanobacterial to algal world and the emergence of animals". Emerging Topics in Life Sciences. 2 (2): 181–190. doi:10.1042/ETLS20180039. ISSN 2397-8554. PMID 32412625.
  4. ^ Arnaud, Emmanuelle; Halverson, Galen P.; Shields-Zhou, Graham Anthony (30 November 2011). "Chapter 1: The geological record of Neoproterozoic ice ages". Geological Society, London, Memoirs. 36 (1): 1–16. doi:10.1144/M36.1.
  5. ^ Howchin, Walter (1920). "Past Glacial Action in Australia". Year Book. Vol. 13. Australia: Australian Bureau of Statistics. pp. 1133–1146.
  6. ^ a b c Lloyd, Jarred Cain; Preiss, Wolfgang V.; Collins, Alan S.; Virgo, Georgina M.; Blades, Morgan L.; Gilbert, Sarah E.; Subarkah, Darwinaji; Krapf, Carmen B. E.; Amos, Kathryn J. (2022-03-24). "Geochronology and formal stratigraphy of the Sturtian Glaciation in the Adelaide Superbasin". Geological Magazine. 160 (7): 1321–1344. doi:10.31223/x50g9n. hdl:2440/140662 – via EarthArXiv.
  7. ^ "Australian Stratigraphic Units Database, Geoscience Australia". asud.ga.gov.au. Retrieved 2023-01-04.
  8. ^ "Barker, Collet (1784–1831)". Australian Dictionary of Biography. National Centre of Biography, Australian National University.
  9. ^ "Captain Charles Sturt". Flinders Ranges Research and South Australian History. Retrieved 2007-12-24.
  10. ^ Mawson, Douglas; Sprigg, Reginald (1950). "Subdivision of the Adelaide System". Australian Journal of Science. 13 (3): 69–72.
  11. ^ Dunn, P. R.; Thomson, B. P.; Rankama, Kalervo (1971). "Late Pre-Cambrian Glaciation in Australia as a Stratigraphic Boundary". Nature. 231 (5304): 498–502. Bibcode:1971Natur.231..498D. doi:10.1038/231498a0. ISSN 1476-4687. S2CID 4298290.
  12. ^ Cooper, Barry (2010-12-01). "'Snowball Earth': The Early Contribution from South Australia". Earth Sciences History. 29 (1): 121–145. Bibcode:2010ESHis..29..121C. doi:10.17704/eshi.29.1.j8874825610u68w5. ISSN 0736-623X.
  13. ^ Eyles, Nicholas; Young, Grant (1994). "Geodynamic controls on glaciation in Earth history". In Deynoux, M.; Miller, J. M. G.; Domack, E. W.; Eyles, N.; Fairchild, I. J.; Young, G. M. (eds.). Earth's Glacial Record. Cambridge: Cambridge University Press. pp. 5–10. ISBN 978-0521548038.
  14. ^ Arnaud, Emmanuelle; Eyles, Carolyn H. (2002). "Glacial influence on Neoproterozoic sedimentation: the Smalfjord Formation, northern Norway". Sedimentology. 49 (4): 765–788. Bibcode:2002Sedim..49..765A. doi:10.1046/j.1365-3091.2002.00466.x. S2CID 128719279.
  15. ^ "What turned Earth into a giant snowball 700 million years ago? Scientists now have an answer". ScienceDaily. 7 February 2024. Archived from the original on 25 March 2024. Retrieved 1 April 2024.
  16. ^ Zhao, Kun; Lang, Xianguo; Zhu, Shengxian (August 2023). "An ice sheet advancing sequence at the beginning of the Cryogenian Sturtian glaciation". Global and Planetary Change. 227: 104185. Bibcode:2023GPC...22704185Z. doi:10.1016/j.gloplacha.2023.104185. Retrieved 2 October 2024 – via Elsevier Science Direct.
  17. ^ Bowyer, Fred T.; Krause, Alexander J.; Song, Yafang; Huang, Kang-Jun; Fu, Yong; Shen, Bing; Li, Jin; Zhu, Xiang-Kun; Kipp, Michael A.; van Maldegem, Lennart M.; Brocks, Jochen J.; Shields, Graham A.; Le Hir, Guillaume; Mills, Benjamin J. W.; Poulton, Simon W. (25 August 2023). "Biological diversification linked to environmental stabilization following the Sturtian Snowball glaciation". Science Advances. 9 (34): eadf9999. Bibcode:2023SciA....9F9999B. doi:10.1126/sciadv.adf9999. ISSN 2375-2548. PMC 10456883. PMID 37624887.


Quelle: http://en.wikipedia.org/wiki/Sturtian_glaciation