Glaciations Phanerozoic

The ancient evaporites of the Phanerozoic eon were deposited at rates as fest as 100 m per lOOOy. These rapid rates are thought to have been caused by a lowering of sea level associated with tectonic activity and glaciation. Some of the largest of the salt giants are the Messinian evaporites that formed in the Mediterranean Sea during the late Miocene epoch, 5.5 to 6.5mybp. 

Figure 8 Archean distribution of banded iron formations, with short reoccurrence associated with widespread glaciation in the Neoproterozoic, and the Proterozoic and Phanerozoic distribution of sedimentary rocks containing ferric-iron cements (red beds). The end of banded iron formation and beginning of red bed deposition at —2.2 Ga has been taken as evidence for a major oxygenation event in Earth s atmosphere.

The Neoproterozoic interval witnessed supercontinent formation and breakup and profound global-scale glaciations that persisted for perhaps millions of years (Knoll 1991). It therefore is not surprising that this interval experienced substantial isotopic excursions reminiscent of those during the Paleoproterozoic (Fig. 10). Eukaryotic lineages that would lead directly to plants and animals had developed by this time. It is generally believed that the events associated with tectonics, climate and the biogeochemical cycles played important roles in the enormous diversification of plant and animal life at the dawn of the Phanerozoic Eon. 

Crowley TJ (2000) Carbon dioxide and Phanerozoic chmate. In Huber BT, MacLeod KG (eds) Warm Climates in Earth Histoiy. University of Cambridge Press, Cambridge, UK, p 425-444 Crowley TJ, Baum SK (1991) Towards reconciliation of Late Ordovician (-440 Ma) glaciation with very high CO2 levels. J Geophys Res 96 22,597-22,610... 

CroweU JC, Frakes LA (1970) Phanerozoic glaciation and the causes of ice ages. Amer J Sci 268 193-224 CuUington AL (1963) The geomagnetic secular variation in the Ross Dependency. New Zealand J Geol Geophys 6(3) 444-453... 

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