Multiple sulfur isotopes of sulfides from sediments in the aftermath of Paleoproterozoic glaciations

TL;DR: Canfield et al. as discussed by the authors presented a review of recent works in multiple sulfur isotope geochemistry with a focus on results that inform our understanding of biogeochemical processes and Earth surface evolution.

TL;DR: In this paper, a 1-D numerical model was used to study the atmospheric photochemistry of oxygen, methane, and sulfur after the advent of oxygenic photosynthesis, and it was shown that the disappearance of a strong MIF sulfur signature at the beginning of the Proterozoic is better explained by the collapse of atmospheric methane, rather than by a failure of volcanism or the rise of oxygen.

TL;DR: Anomalous sulphur isotope signatures indicating mass-independent fractionation (MIF) in olivine-hosted sulphides from 20-million-year-old ocean island basalts from Mangaia, Cook Islands (Polynesia), which have been suggested to sample recycled oceanic crust, suggest that sulphur was subducted into the mantle before 2.45 billion years ago and recycled into theantle source of Mangaia lavas.

TL;DR: Mass-independent isotopic signatures in Precambrian rocks indicate that a change occurred in the sulfur cycle between 2090 and 2450 million years ago, implying that atmospheric oxygen partial pressures were low and that the roles of oxidative weathering and of microbial oxidation and reduction of sulfur were minimal.

TL;DR: The recent discovery that late Neoproterozoic ice sheets extended to sea level near the equator poses a palaeoenvironmental conundrum as discussed by the authors, which does not account for major features such as abrupt onsets and terminations of discrete glacial events, their close association with large (> 10&) negative d 13 C shifts in seawater proxies, the deposition of strange carbonate layers (cap carbonates) globally during postglacial sea-level rise, and the return of large sedimentary iron formations.

TL;DR: The existence of a supercontinent existing before Rodinia, referred to herein as Columbia, a name recently proposed by Rogers and Santosh [Gondwana Res. 5 (2002) 5] for a Paleo-Mesoproterozoic super-continent, was confirmed by available lithostratigraphic, tectonothermal, geochronological and paleomagnetic data as mentioned in this paper.

TL;DR: It is found that syngenetic pyrite is present in organic-rich shales of the 2.32-Gyr-old Rooihoogte and Timeball Hill formations, South Africa, indicating that atmospheric oxygen was present at significant levels during the deposition of these units.