Summary: The Great Oxygenation Event

Prior to the Great Oxygenation Event (GOE) there was little oxygen in the atmosphere. Oxygenation of the atmosphere occurred in two steps, at the beginning and end of the Proterozoic eon (Frei, et al., 2013). In the GOE the surface oceans began to become oxygenated (Holland, 2006). The Second stage of oxygenation is known as the Neoproterozoic Oxygenation Event (NOE) and occurred after the 650-635Ma in the Marinoan glaciation (Sahoo, et al., 2012) (Feulner & Kienert, 2014). The NOE is thought to represent either further oxygenation (Holland, 2009) or deep ocean oxygenation (Canfield, 1998). This event is marked by resurgence in Banded Iron Formation (BIF) deposits which mark this second marine oxidation (Ilyin, 2009) (Frei, et al., 2009). The Marinoan and the Sturtian glaciations were two …show more content…
The Great Oxidation Event (GOE) occurred before the Neoproterozoic and lead to the oxygenation of the upper ocean, or parts of it. After this event however no further significant oxidation occurred meaning ocean oxygen introduced by the GOE is likely to have been used up by bacterial respiration, weathering and hydrothermal processes (Stern, et al., 2013). These processes could not have continued into the snowball Earth glaciations as the theory of snowball earth states a frozen sea must be present (Hoffman, et al., 1998). It does not however dictate that the continents also must be entirely frozen. However for no hydrological cycle and thus no weathering or carbon dioxide draw down to occur most continental areas would have to be covered by at least thin ice sheets. This is evidence that the seas remained anoxic throughout the snowball glaciations. If these glaciations can be attributed to δ13 C excursions in the Neoproterozoic it proves that the marine biosphere changed prior to the Snowball glaciations. This change could potentially have been caused by input of DOC (Tziperman, et al.,