Calibrating the Cryogenian

Macdonald, Francis A.; Schmitz, Mark D.; Crowley, James L.; Roots, C F; Jones, David S.; Maloof, Adam C.; Strauss, Justin V.; Cohen, Phoebe; Johnston, David T.; Schrag, Daniel P.

doi:10.1126/science.1183325

Cited by 522 publications

(391 citation statements)

References 29 publications

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“…The massive Franklin LIP at ca. 717 Ma (45) immediately preceded the most dramatic and longest global glaciation of the Neoproterozoic, the Sturtian (46). This overall period is characterized by the second most dramatic change in surface redox conditions linked with Snowball Earth glaciations (47) and accompanied high rates of organic carbon burial (48,49).…”

Section: Discussionmentioning

confidence: 99%

Timing and tempo of the Great Oxidation Event

Gumsley

Chamberlain

Bleeker

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

407

274

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The first significant buildup in atmospheric oxygen, the Great Oxidation Event (GOE), began in the early Paleoproterozoic in association with global glaciations and continued until the end of the Lomagundi carbon isotope excursion ca. 2,060 Ma. The exact timing of and relationships among these events are debated because of poor age constraints and contradictory stratigraphic correlations. Here, we show that the first Paleoproterozoic global glaciation and the onset of the GOE occurred between ca. 2,460 and 2,426 Ma, ∼100 My earlier than previously estimated, based on an age of 2,426 ± 3 Ma for Ongeluk Formation magmatism from the Kaapvaal Craton of southern Africa. This age helps define a key paleomagnetic pole that positions the Kaapvaal Craton at equatorial latitudes of 11°± 6°at this time. Furthermore, the rise of atmospheric oxygen was not monotonic, but was instead characterized by oscillations, which together with climatic instabilities may have continued over the next ∼200 My until ≤2,250-2,240 Ma. Ongeluk Formation volcanism at ca. 2,426 Ma was part of a large igneous province (LIP) and represents a waning stage in the emplacement of several temporally discrete LIPs across a large low-latitude continental landmass. These LIPs played critical, albeit complex, roles in the rise of oxygen and in both initiating and terminating global glaciations. This series of events invites comparison with the Neoproterozoic oxygen increase and Sturtian Snowball Earth glaciation, which accompanied emplacement of LIPs across supercontinent Rodinia, also positioned at low latitude.Great Oxidation Event | Snowball Earth | Paleoproterozoic |

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Section: Discussionmentioning

confidence: 99%

Timing and tempo of the Great Oxidation Event

Gumsley

Chamberlain

Bleeker

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

407

274

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“…Chuar sediments were deposited in a shallow marine restricted seaway [14] located within 188 of the palaeoequator [15]. A U-Pb detrital zircon age of ca 782 Ma from the underlying Nankoweap Formation [16] and a U-Pb zircon age of 742 + 6 Ma from an ash at the top of the Chuar Group [17] place these strata in the late Tonian Period of the Neoproterozoic Era, about 20 Myr prior to the 'snowball Earth' glaciations [18], during the first major diversification of eukaryotes [9].…”

Section: Background and Methodsmentioning

confidence: 99%

Tiny vampires in ancient seas: evidence for predation via perforation in fossils from the 780–740 million-year-old Chuar Group, Grand Canyon, USA

Porter¹

2016

Proc. R. Soc. B.

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One explanation for the Early Neoproterozoic expansion of eukaryotes is the appearance of eukaryovorous predators—i.e. protists that preyed on other protists. Evidence for eukaryovory at this time, however, is indirect, based on inferences from character state reconstructions and molecular clocks, and on the presence of possible defensive structures in some protistan fossils. Here I describe 0.1–3.4 µm circular holes in seven species of organic-walled microfossils from the 780–740 million-year-old Chuar Group, Grand Canyon, Arizona, USA, that are similar to those formed today by predatory protists that perforate the walls of their prey to consume the contents inside. Although best known in the vampyrellid amoebae, this ‘vampire-like’ behaviour is widespread among eukaryotes, making it difficult to infer confidently the identity of the predator. Nonetheless, the identity of the prey is clear: some—and perhaps all—of the fossils are eukaryotes. These holes thus provide the oldest direct evidence for predation on eukaryotes. Larger circular and half-moon-shaped holes in vase-shaped microfossils from the upper part of the unit may also be the work of ‘tiny vampires’, suggesting a diversity of eukaryovorous predators lived in the ancient Chuar sea.

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“…The 720 Ma lower Cryogenian boundary is close to a cluster of precise U-Pb dates on zircons recording the onset of glaciation in NW Canada (716-717 Ma, Macdonald et al 2010), Oman (711 Ma, Bowring et al, 2007) and South China (716 Ma, Lan et al, 2014). Likewise, the basal, globally correlated cap carbonate to the Marinoan glaciation, which defines the Cryogenian-Ediacaran boundary, is well-constrained to ca.…”

Section: Introductionmentioning

confidence: 99%

The Late Cryogenian Warm Interval, NE Svalbard: Chemostratigraphy and genesis

Fairchild

Bonnand²,

Davies

et al. 2016

Precambrian Research

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms At the base of E3, interstratification of cap carbonate with ice-rafted and redeposited glacial sediments occurs. Early diagenetic stabilization of carbonate mineralogy from a precursor, possibly ikaite, to calcite or dolomite is inferred. E3 is predominantly dolomitic silt-shale, with sub-millimetre lamination, lacking sand or current-related sedimentary structures. Thin fine laminae are partly pyritized and interpreted as microbial mats. Dolomite content is 25-50%, with δ 13 C values consistently around +4‰, a value attributed to buffering by dissolution of a precursor metastable carbonate phase. Local calcite cement associates with low δ 13 C values. The carbonates form silt-sized, chemically zoned rhombic crystals from an environment with dynamically changing Fe and Mn. Three-dimensional reconstructions of cm-scale disturbance structures indicate that they represent horizontally directed sock-like folds, developed by release of overpressure into thin surficial sediment overlying an early-cemented layer.A shoaling upwards unit near the top of E3 displays calcium sulphate pseudomorphs in dolomite in the north, but storm-dominated limestones in the south, both being overlain by peritidal oolitic dolomites, exposed under the succeeding Wilsonbreen glacial deposits. There is no Trezona δ 13 C anomaly, possibly implying top-truncation of the succession.Regular 0.5 m-scale sedimentary rhythms, reflecting subtle variations in sediment texture or composition occur throughout E3 and are interpreted as allocyclic. They are thought to be mainly primary in origin, locally modified slightly during early diagenetic cementation. Rhythms are proposed to represent ca. 18 kyr precession cycles, implying 6-8 Myr deposition between glaciations.

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Calibrating the Cryogenian

Cited by 522 publications

References 29 publications

Timing and tempo of the Great Oxidation Event

Timing and tempo of the Great Oxidation Event

Tiny vampires in ancient seas: evidence for predation via perforation in fossils from the 780–740 million-year-old Chuar Group, Grand Canyon, USA

The Late Cryogenian Warm Interval, NE Svalbard: Chemostratigraphy and genesis

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