Dating the rise of atmospheric oxygen

Abstract

Several lines of geological and geochemical evidence indicate that the level of atmospheric oxygen was extremely low before 2.45 billion years (Gyr) ago, and that it had reached considerable levels by 2.22 Gyr ago. Here we present evidence that the rise of atmospheric oxygen had occurred by 2.32 Gyr ago. We found that syngenetic pyrite is present in organic-rich shales of the 2.32-Gyr-old Rooihoogte and Timeball Hill formations, South Africa. The range of the isotopic composition of sulphur in this pyrite is large and shows no evidence of mass-independent fractionation, indicating that atmospheric oxygen was present at significant levels (that is, greater than 10(-5) times that of the present atmospheric level) during the deposition of these units. The presence of rounded pebbles of sideritic iron formation at the base of the Rooihoogte Formation and an extensive and thick ironstone layer consisting of haematitic pisolites and oölites in the upper Timeball Hill Formation indicate that atmospheric oxygen rose significantly, perhaps for the first time, during the deposition of the Rooihoogte and Timeball Hill formations. These units were deposited between what are probably the second and third of the three Palaeoproterozoic glacial events.

Osmium evidence for synchronicity between a rise in atmospheric oxygen and Palaeoproterozoic deglaciation

“…For the measurements of Mo and U abundance, we used ~100 mg of the rock powder. The powder samples were digested with HNO 3 , HClO 4 and HF. After evaporation of acids to near dryness, the residues were dissolved in a HNO 3 (2%) and HF (0.1%) solution.…”

“…E arth's atmosphere is suggested to have shifted from anoxic to oxic in early Palaeoproterozoic during ~2.45-2.2 billion years ago (Ga) [1][2][3][4][5][6][7][8] . Any increase in O 2 would have resulted in reduced atmospheric methane levels, triggering glaciations 2 .…”

Iron formations: A global record of Neoarchaean to Palaeoproterozoic environmental history

“…2.4 Ga because of greater iron solubility under reducing conditions (e.g., Rye and Holland, 1998); (3) the appearance of red beds after ca. 2.3 Ga (e.g., Roscoe, 1969;Chandler, 1980;Melezhik et al, 2005;Bankole et al, 2016); (4) the loss of S-MIF in sulfide and sulfate minerals in sedimentary rocks deposited after 2.3 Ga (Farquhar et al, 2000;Bekker et al, 2004;Papineau et al, 2007;Partridge et al, 2008;Guo et al, 2009;Williford et al, 2011;Luo et al, 2016;Gumsley et al, 2017); and (5) the increase in Cr and U contents in IF at 2.45 Ga that records the onset of oxidative continental weathering Partin et al, 2013a). anomaly (Alibert and McCulloch, 1993), suggesting a strong hydrothermal imprint on the REE systematics during its deposition, although, as noted above (Fig.…”

A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia

“…In addition, the low concentrations of some redox-sensitive elements (e.g., Mo, U) in sedimentary archives suggest low seawater concentrations of these elements because of their limited oxidative mobilization from the Archean continental crust (Scott et al, 2008;Partin et al, 2013). The Great Oxidation Event (GOE) is marked by a permanent increase of atmospheric O 2 content to >0.001% present atmospheric level (PAL), starting between 2.45 and 2.32 Ga (Pavlov and Kasting, 2002;Bekker et al, 2004;Gumsley et al, 2017). This transition was accompanied by the appearance of new mineral species containing redox-sensitive elements in their highest oxidation states, reduction in BIF deposition, disappearance of S-MIF, and an increase in seawater Mo, U, and sulfate concentrations Schrö der et al, 2008;Scott et al, 2008Scott et al, , 2014Sverjensky and Lee, 2010;Hazen et al, 2011;Planavsky et al, 2012;Reuschel et al, 2012;Partin et al, 2013;Reinhard et al, 2013a).…”