Global InformationGaskiers glaciation information
The Gaskiers glaciation is a period of widespread glacial deposits (e.g. diamictites) that lasted under 340,000 years, between 579.88 ± 0.44 and 579.63 ± 0.15 million years ago[1] — i.e. late in the Ediacaran Period — making it the last major glacial event of the Precambrian.[2] It was also the last and the shortest of at least three major ice ages in the Neoproterozoic era. It is assumed that, in contrast to the Sturtian and Marinoan glaciations, it did not lead to global glaciation ("Snowball Earth").[3]
Deposits attributed to the Gaskiers — assuming that they were all deposited at the same time — have been found on eight separate paleocontinents, in some cases occurring close to the equator (at a latitude of 10–30°). The 300-metre-thick (984 ft) name-bearing section at Gaskiers (Newfoundland) is packed full of striated dropstones.[1] Its δ13C values are very low (pushing 8‰), consistent with a period of environmental abnormality.[1] The bed lies just below some of the oldest fossils of the Ediacaran biota, leading to early suggestions that the passing of the glaciation and the subsequent sharp rise in the ocean oxygen levels may have paved the way for the evolution of these odd organisms.[4] More accurate dating methods have shown that there is a 9-million-year gap between the diamictites and the 570 Ma macrofossils.[1]
The Bou-Azzer glaciation, an Ediacaran glaciation known from evidence collected from the West African Craton, may be equivalent to the Gaskiers glaciation. Alternatively, it has also been suggested to have been part of a glacial event later in the Ediacaran.[3]
- ^ a b c d Pu, Judy P.; Bowring, Samuel A.; Ramezani, Jahandar; Myrow, Paul; Raub, Timothy D.; Landing, Ed; Mills, Andrea; Hodgin, Eben; MacDonald, Francis A. (2016). "Dodging snowballs: Geochronology of the Gaskiers glaciation and the first appearance of the Ediacaran biota". Geology. 44 (11): 955. Bibcode:2016Geo....44..955P. doi:10.1130/G38284.1.
- ^ F. M. Gradstein, Gabi Ogg, Mark Schmitz, The Geologic Time Scale, Elsevier, 2012, p. 428.
- ^ a b Vernhet, E.; Youbi, N.; Chellai, E. H.; Villeneuve, M.; El Archi, A. (February 2012). "The Bou-Azzer glaciation: Evidence for an Ediacaran glaciation on the West African Craton (Anti-Atlas, Morocco)". Precambrian Research. 196–197: 106–112. Bibcode:2012PreR..196..106V. doi:10.1016/j.precamres.2011.11.009. Retrieved 17 December 2022.
- ^ D. E. Canfield, S. W. Poulton, G. M. Narbonne (January 2007). "Late-Neoproterozoic deep-ocean oxygenation and the rise of animal life". Science. 315 (5808): 92–95. Bibcode:2007Sci...315...92C. doi:10.1126/science.1135013. PMID 17158290. S2CID 24761414.
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