Varanger glaciation: Difference between revisions
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The Varanger Glacial Event (sometimes termed the Stuartian-Varangian with Stuartian being the earlier part) was a world wide glaciation that occurred around 950-600 Million Years Ago. The population of acritarchs crashed during this glaciation and it is claimed that |
The Varanger Glacial Event (sometimes termed the [[Stuartian-Varangian]] with [[Stuartian]] being the earlier part) was a world wide [[glaciation]] that occurred around 950-600 Million Years Ago. The population of [[acritarchs]] crashed during this glaciation and it is claimed that [[oxygen]] levels in the [[atmosphere]] increased after the glaciation. There are a number of enigmatic features with regard to this glaciation including indications of glaciation at very low latitudes and the presence of [[limestone]]s -- normally warm [[water]] sediments above, below and intermixed with glacial deposits. [[Paleomagnetism]] seems to indicate very high [[continental drift]] rates leading some geologists to question whether some of the phenomena might be due to [[magnetic pole]] wandering rather than plate motion and low [[latitiude]] glaciation. However, cabon isotope analysis indicates that several worldwide glaciations may have occurred. Evidence of the Varanger event is found in various places and times: The [[Congo]] from 950-750Ma and 620-600Ma. [[Australia]] from 800-780Ma and 690-680Ma. [[China]] 800-760Ma, 740-700Ma and 600Ma; Western [[North America]] 850-800Ma, [[Sahara]] 730-650Ma, [[Norway]] 650Ma. [[Spitzpergen]] 593-573Ma. Other known world wide glaciations include the [[Huronian]] from 2400Ma to 2100Ma, [[Andean-Saharan]] from 450-420Ma, the [[Karoo]] glaciation from 360Ma to 260Ma, and the [[Cenozoic]] glaciation which started 30Ma in [[Antarctica]] and may not be over. |
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Revision as of 15:51, 25 February 2002
The Varanger Glacial Event (sometimes termed the Stuartian-Varangian with Stuartian being the earlier part) was a world wide glaciation that occurred around 950-600 Million Years Ago. The population of acritarchs crashed during this glaciation and it is claimed that oxygen levels in the atmosphere increased after the glaciation. There are a number of enigmatic features with regard to this glaciation including indications of glaciation at very low latitudes and the presence of limestones -- normally warm water sediments above, below and intermixed with glacial deposits. Paleomagnetism seems to indicate very high continental drift rates leading some geologists to question whether some of the phenomena might be due to magnetic pole wandering rather than plate motion and low latitiude glaciation. However, cabon isotope analysis indicates that several worldwide glaciations may have occurred. Evidence of the Varanger event is found in various places and times: The Congo from 950-750Ma and 620-600Ma. Australia from 800-780Ma and 690-680Ma. China 800-760Ma, 740-700Ma and 600Ma; Western North America 850-800Ma, Sahara 730-650Ma, Norway 650Ma. Spitzpergen 593-573Ma. Other known world wide glaciations include the Huronian from 2400Ma to 2100Ma, Andean-Saharan from 450-420Ma, the Karoo glaciation from 360Ma to 260Ma, and the Cenozoic glaciation which started 30Ma in Antarctica and may not be over.