Huronian glaciation

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The Huronian glaciation (or Makganyene glaciation) was a glaciation that extended from 2400 Mya to 2100 Mya, during the Siderian and Rhyacian periods of the Paleoproterozoic era. The Huronian glaciation followed after the Great Oxygenation Event (GOE), a time when increased atmospheric oxygen decreased atmospheric methane.

It is the oldest known ice age, occurring at a time when only simple, unicellular life existed on Earth.

Name origin[edit]

This geological era was named from geologic findings in the Lake Huron region in North America where three separate horizons of glacial deposits are separated by non-glacial sediment.

Geological context[edit]

The Huronian glaciation was one of the most severe and longest ice ages in geologic history.

Causes[edit]

It is possible that there were multiple contributing factors.

As the Sun was notably weaker at the time, the Earth's climate may have relied on methane, a powerful greenhouse gas, to maintain surface temperatures above freezing. The Huronian glaciation occurred at around the time the earth became aerobic, the Great Oxygenation Event. This rise of oxygen resulted in the elimination of methane in the atmosphere, which in turn could have led to decreased temperatures.[1]

Drawdown of atmospheric carbon dioxide, also a greenhouse gas (albeit weaker), has also been suggested. CO2 levels could have been reduced due to increased silicate weathering of fresh basaltic surfaces[1] or due to a 250 million year lull in volcanic activity reducing the amount of released CO2.

Finally, the placement of the continental landmasses (a probable cause of the Cryogenian glaciation), and the Earth's orbit around the Sun may have been contributing factors.

References[edit]

  1. ^ a b Melezhik, V.A. (2006). "Multiple causes of Earth's earliest global glaciation". Terra Nova 18 (2): 130–137. doi:10.1111/j.1365-3121.2006.00672.x. 
Proterozoic Eon
Paleoproterozoic EraMesoproterozoic EraNeoproterozoic Era
SiderianRhyacianOrosirianStatherianCalymmianEctasianStenianTonianCryogenianEdiacaran