Variations in the abundance of photosynthetic oxygen through Precambrian and Paleozoic time in relation to biotic evolution and mass extinctions: evidence from Mn/Fe ratios

Abstract

This paper reports new information about variations in the abundance of photosynthetic oxygen through Precambrian and Paleozoic time. Non-detrital marine sediments (cherts, limestones, and dolomite) were analysed for NH 2 OH•HCl/acetic acid-extractable Mn and Fe, and the Mn/Fe ratio (a proxy for the oxidationreduction potential of the sediment at the time of deposition) was plotted against geologic age. The method has never before been applied to ancient sediments, but previously published data produced independently by other methods confirmed its applicability and underlying assumptions. The Mn/Fe ratio was unexpectedly high ca. 3.416 Ga, implying localised oxidation due to oxygen production by cyanobacteria, but fell dramatically over the interval 3.416-3.298 Ga, suggesting mass mortality or mass extinction of early Archean cyanobacteria owing to asteroid impacts. However, the ratio increased continuously, though at episodically varying rates, from a minimum at ~1.8783 Ga to a maximum at ~0.680 Ga, signifying accumulation of oxygen in the atmosphere and hydrosphere. The rate of increase was relatively high at first but dropped abruptly at some point during the interval 1.8783-1.6 Ga, possibly signaling the appearance of eukaryotic herbivores. The ratio increased exponentially from 1.6 to 0.8 Ga and then rose more rapidly from 0.8 to 0.680 Ga, indicating a late Proterozoic upsurge of oxygen production, whereupon it fell catastrophically to a minimum in the Cambrian, reflecting widespread anoxia due to mass extinction of Ediacaran organisms. The crisis at the Precambrian-Cambrian boundary was followed by a logarithmic increase from the Cambrian to the Permian, indicating a resurgence of photosynthetic activity.

A Tonian age for the Visingsö Group in Sweden constrained by detrital zircon dating and biochronology: implications for evolutionary events

“…Shallow marine habitats must have been relatively well oxygenated to sustain planktonic and benthic autotrophs, allowing them to fulfil their metabolic and life cycle requirements for sexual reproduction, as known from modern analogues (see discussion by Moczydłowska, 2008 a , 2016). Relatively well-oxygenated ocean surface waters or at least oxygenated local basins in such a state are supported by geochemical studies (Jackson, 2015; Lalonde & Konhauser, 2015; Turner & Bekker, 2016; Spence, Le Heron & Fairchild, 2016) and this is in agreement with the presence of a microbiota of inferred algal affinities that were reproducing sexually in the Visingsö Group at the time, and in contemporaneous successions. Progressive evolution of phytoplankton in the Tonian Period, evident by comparison with the Mesoproterozoic record (Yan & Liu, 1993; Javaux, Knoll & Walter, 2004; Lamb et al .…”

“…2013). The oxygen level rose owing to the steady-state photosynthetic production of free oxygen (Falkowski & Raven, 2007; Jackson, 2015; Schirrmeister, Gugger & Donoghue, 2015), and cyanobacteria and red and green algae thrived at the time (Schopf, 1992; Butterfield, 2000; Sergeev, 2006; Moczydłowska, 2008 a , 2016; Love et al . 2009; Moczydłowska et al .…”

“…2.3 Ga; Holland, 2002; Bekker et al . 2004) or possibly earlier (Lyons, Reinhard & Planavsky, 2014; Jackson, 2015; Lalonde & Konhauser, 2015). The ocean redox state fluctuated but oxygen content increased in Neoproterozoic time (Halverson et al .…”