Claypool continued: Extending the isotopic record of sedimentary sulfate

Free and kerogen‐bound biomarkers from late Tonian sedimentary rocks record abundant eukaryotes in mid‐Neoproterozoic marine communities

“…800 Ma and onwards. This is approximately synchronous with observed volatility in Neoproterozoic carbon isotopic records (Halverson et al, ; Shields‐Zhou & Och, ) and increases in the abundance and diversity of eukaryotic acritarchs and other fossils (Butterfield et al, ; Knoll, ; Knoll et al, ; Morais et al, ; Porter & Knoll, ; Strauss et al, ) along with striking changes in marine seawater chemistry, primary productivity and ocean redox conditions (Crockford et al, , ; Isson et al, ; Kuznetsov et al, ; Lenton et al, ; Lenton & Daines, ; Turner & Bekker, ; von Strandmann et al, ), suggesting a more oxygenated and productive marine biosphere.…”

“…A transition to a world with elevated surface oxygenation and nutrients, capable of supporting a more complex and productive marine biosphere, likely occurred during the Neoproterozoic Era (1,000–541 Ma). This is supported by multiple lines of evidence for first‐order perturbations in climatic and tectonic conditions (Evans, ; Hoffman et al, ; Hoffman, Kaufman, Halverson, & Schrag, ; Kuznetsov, Bekker, Ovchinnikova, Gorokhov, & Vasilyeva, ; Li et al, ; Li, Evans, & Halverson, ; Macdonald et al, ; Maloof et al, ; McKenzie, Hughes, Gill, & Myrow, ; Rooney et al, ), ocean‐atmosphere redox (Canfield, ; Husson & Peters, ; Johnston et al, ; Kump, ; Laakso & Schrag, ; Lenton & Daines, ; Planavsky et al, ; Prince, Rainbird, & Wing, ; Shields‐Zhou & Och, ; von Strandmann et al, ; Turner & Bekker, ), carbon and other element cycling (Ader et al, ; Bjerrum & Canfield, ; Canfield & Teske, ; Crockford et al, , ; Fike, Grotzinger, Pratt, & Summons, ; Halverson, Hoffman, Schrag, Maloof, & Rice, ; Horton, ; Lenton, Boyle, Poulton, Shields‐Zhou, & Butterfield, ; Logan, Hayes, Hieshima, & Summons, ; Marais, Strauss, Summons, & Hayes, ; McFadden et al, ; Ridgwell & Zeebe, ; Schrag, Higgins, Macdonald, & Johnston, ), and for biological innovations/radiations (Bosak et al, ; Bosak, Macdonald, Lahr, & Matys, ; Brocks et al, ; Butterfield, ; Falkowski et al, ; Knoll, ; Love et al, ; Porter, ; Porter & Knoll, ; Porter, Meisterfeld, & Knoll, ; Sperling & Stockey, ).…”

A productivity collapse to end Earth’s Great Oxidation

“…2,018.5 to 2,015.4 Ma) are similar to those deposited in the ca. 1,700-Ma Myrtle Shale Formation (14) and ca. 1,400-Ma Sibley Group (19), suggesting that the transition out of the GOE marks the onset of conditions that may have persisted across the >600-My interval separating these deposits ( Fig.…”

“…This large release of phosphorus would have then sustained the posited oxygen overshoot in a feast-like scenario (6,8). In marked contrast to the elevated GPP hypothesized for the GOE, evidence has been presented that characterizes the mid-Proterozoic [∼2,000 to 1,100 Ma (14)] as an interval of remarkably low GPP, possibly just 6% of modern levels (14,19). Although GPP changes across this transition have been assumed (16), quantifying the degree to which the GOE deviated from the mid-Proterozoic GPP state remains largely unexplored, and how quickly such a transition in the biosphere occurred to mark the end of the GOE remains unknown.…”

“…This controversy surrounding the LJE has motivated independent tests of whether such an oxygen overshoot, and corresponding transition from a high-pO 2 syn-Great Oxidation Event (GOE) state to a comparatively low-pO 2 post-GOE state, even occurred. Numerous independent proxies, while differing in degree of severity, broadly characterize this interval as a decline in surface environment oxidant inventories (12)(13)(14)(15)(16)(17)(18). However, it is worth noting that many such records may better reflect local depositional environments and not necessarily global conditions.…”