Huronian glaciation

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The Huronian glaciation (or Makganyene glaciation)

Gya), during the Siderian and Rhyacian periods of the Paleoproterozoic era. Evidence for glaciation is mainly based on the recognition of diamictite, that is interpreted to be of glacial origin. Deposition of the Huronian succession is interpreted to have occurred within a rift basin that evolved into a largely marine passive margin setting.[2]
The glacial diamictite deposits within the Huronian are on par in thickness with Quaternary analogs.

Description

The three glacial diamictite-bearing units of the Huronian are, from the oldest to youngest, the Ramsay Lake, Bruce, and Gowganda formations. Although there are other glacial deposits recognized throughout the world at this time, the Huronian is restricted to the region north of Lake Huron, between Sault Ste. Marie, Ontario, and Rouyn-Noranda, Quebec. Other similar deposits are known from elsewhere in North America, as well as Australia and South Africa.[3]

The Huronian glaciation broadly coincides with the

shallow seas.[5][6]

Discovery and name

In 1907, Arthur Philemon Coleman first inferred a "lower Huronian ice age"[7][8] from analysis of a geological formation near Lake Huron in Ontario. In his honour, the lower (glacial) member of the Gowganda Formation is referred to as the Coleman member. These rocks have been studied in detail by numerous geologists and are considered to represent the type example of a Paleoproterozoic glaciation.[9][10]

The confusion of the terms

Diachronic or geochronometric
units should be used.

Geology and climate

The Gowganda Formation (2.3 Gya) contains "the most widespread and most convincing glaciogenic deposits of this era", according to Eyles and Young. In North America, similar-age deposits are exposed in Michigan, the

Griquatown Basin of South Africa, as well as India and Australia.[13]

The tectonic setting was one of a rifting continental margin. New continental crust would have resulted in chemical weathering. This weathering would pull CO2 out of the atmosphere, cooling the planet through the reduction in greenhouse effect.[citation needed]

Popular perception is that one or more of the glaciations may have been snowball Earth events, when all or most of Earth's surface was covered in ice.[11][14][15] However the palaeomagnetic evidence that suggests ice sheets were present at low latitudes is contested,[16][17] and the glacial sediments (diamictites) are discontinuous, alternating with carbonate and other sedimentary rocks, indicating temperate climates, providing scant evidence for global glaciation.

Implications

Before the Huronian Ice Age, most organisms were

Great Oxygenation Event
.

The once-reducing atmosphere, now an oxidizing one, was highly reactive and toxic to the anaerobic biosphere. Further more, atmospheric methane was depleted by oxygen and reduced to trace gas levels, and replaced by much less powerful greenhouse gases such as carbon dioxide and water vapor, the latter of which was also readily precipitated out of the air at low temperatures. Earth's surface temperature dropped significantly, partly because of the reduced greenhouse effect and partly because solar luminosity and/or geothermal activities were also lower at that time,[6] leading to an icehouse Earth.

After the combined impact of oxidization and

eukaryotic organisms during the Proterozoic.[citation needed
]

See also

References

  1. doi:10.1016/j.gsf.2013.02.003
    .
  2. doi:10.1016/S0037-0738(01)00076-8
    .
  3. S2CID 245528915
    , retrieved 16 March 2022
  4. ^ EPA.gov page "Understanding Global Warming Potentials"
  5. ^ "Geologists uncover ancient mass extinction from 2 billion years ago". 5 September 2019.
  6. ^ a b Plait, Phil (28 July 2014). "When a Species Poisons an Entire Planet". Slate Magazine. Retrieved 16 March 2022.
  7. ISSN 0002-9599
    .
  8. ISBN 978-3-642-27833-4
    .
  9. doi:10.1016/0031-0182(70)90070-2
    .
  10. S2CID 4339149
    .
  11. ^
    PMID 16061801
    .
  12. ISSN 0149-1423
    .
  13. ISBN 978-0-521-54803-8
    .
  14. doi:10.1016/j.epsl.2013.08.037
    .
  15. S2CID 244217078
    .
  16. ISSN 0012-821X
    .
  17. PMID 16061801
    .
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