Cryogenian of Yukon

Macdonald, Francis A.; Schmitz, Mark D.; Strauss, Justin V.; Halverson, Galen P.; Gibson, Timothy M.; Eyster, Athena; Cox, Grant; Mamrol, Peter; Crowley, James L.

doi:10.1016/j.precamres.2017.08.015

Cited by 82 publications

(69 citation statements)

References 86 publications

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“…635.5-541 Ma Ediacaran period; [44]) have demonstrated remarkable consistency in the age of two Cryogenian (Sturtian and Marinoan) snowball glaciations globally (Figure 1 and Supplementary Material). For example, the onset of the Sturtian glaciation is now tightly constrained to have begun between 717.5 and 716.5 Ma based on U-Pb zircon ID-TIMS ages acquired on volcanic rocks just below and above the basal glacial contact in the Ogilvie Mountains of Yukon, Canada [50,51]. Similarly, U-Pb zircon ages from the Marinoan glacial deposits [15] and overlying cap carbonates deposited in the immediate aftermath of Snowball glaciation [16] date the boundary between the Cryogenian and Ediacaran periods to 636.6-634.2 Ma.…”

Section: Gssp Refers To Formally Defined Global Stratotype Section Anmentioning

confidence: 99%

Dating the late Proterozoic stratigraphic record

Halverson

Porter

Gibson

2018

Emerging Topics in Life Sciences

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The Tonian and Cryogenian periods (ca. 1000–635.5 Ma) witnessed important biological and climatic events, including diversification of eukaryotes, the rise of algae as primary producers, the origin of Metazoa, and a pair of Snowball Earth glaciations. The Tonian and Cryogenian will also be the next periods in the geological time scale to be formally defined. Time-calibrating this interval is essential for properly ordering and interpreting these events and establishing and testing hypotheses for paleoenvironmental change. Here, we briefly review the methods by which the Proterozoic time scale is dated and provide an up-to-date compilation of age constraints on key fossil first and last appearances, geological events, and horizons during the Tonian and Cryogenian periods. We also develop a new age model for a ca. 819–740 Ma composite section in Svalbard, which is unusually complete and contains a rich Tonian fossil archive. This model provides useful preliminary age estimates for the Tonian succession in Svalbard and distinct carbon isotope anomalies that can be globally correlated and used as an indirect dating tool.

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Section: Gssp Refers To Formally Defined Global Stratotype Section Anmentioning

confidence: 99%

Dating the late Proterozoic stratigraphic record

Halverson

Porter

Gibson

2018

Emerging Topics in Life Sciences

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“…Hoffman et al, 2017) of the Cryogenian Period. This subdivision, though still informal, appears justifiable in light of the geochronological evidence that 1) the Sturtian glaciation is now thought to have begun at c. 717 Ma (Macdonald et al, 2010(Macdonald et al, , 2018McLennan et al, 2018) and ended at c. 660 Ma (Rooney et al, 2015;Cox et al, 2018;Wang et al, 2019) synchronously worldwide, within the uncertainty of available ages, and that 2) the Marinoan glaciation, though shorterlived and of uncertain duration (between about 4 and 17 Myr; Hoffmann et al, 2004;Condon et al, 2005;Prave et al, 2016;Nelson et al, 2020) also ended synchronously at c. 635.5 Ma (Crockford et al, 2018;Zhou et al, 2019). The start of the Cryogenian Period has now been changed to c. 720 Ma so as to encompass only the glacigenic sequences, pending proposal and ratification of a GSSP.…”

Section: IImentioning

confidence: 99%

Towards a new geological time scale: A template for improved rock-based subdivision of pre-Cryogenian time

Shields¹,

Strachan²,

Porter³

et al. 2022

Preprint

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Four first-order (Hadean, Archean, Proterozoic and Phanerozoic eon) and nine second-order (Paleoarchean, Mesoarchean, Neoarchean, Paleoproterozoic, Mesoproterozoic, Neoproterozoic, Paleozoic, Mesozoic and Cenozoic era) units continue to provide intuitive subdivision of geological time. Major transitions in Earth's tectonic, biological and environmental history occurred at approximately 2.5-2.3, 1.8-1.6, 1.0-0.8 and 0.7-0.5 Ga, and so future rock-based subdivision of pre-Cryogenian time, eventually by use of global stratotypes (GSSPs), will likely require only modest deviation from current chronometric boundaries (GSSAs) at 2.5, 1.6 and 1.0 Ga, respectively. Here we argue that removal of GSSAs could be expedited by establishing event-based concepts and provisional, approximate ages for eon-, era-and period-level subdivisions as soon as practicable, in line with ratification of an Ediacaran GSSP in 2004 and chronostratigraphic definition of the Cryogenian Period at c. 720 Ma in 2012. We also outline the geological basis behind current chronometric divisions, explore how they might differ in any future rock-based scheme, identify where major issues might arise during the transition, and outline where some immediate changes to the present scheme could be easily updated/formalised, as a framework for future GSSP development. In line with these aims, we note that the currently recommended four-fold Archean subdivision has not been formally ratified and agree with previous workers that it could be simplified to an informal threefold subdivision, pending more detailed analysis. Although the ages of period boundaries would inevitably change in a more closely rock-based or chronostratigraphic scheme, we support retention of all currently ratified period names. Existing period names, borrowed from the Greek, were chosen to delimit natural phenomena of global reach. Any new global nomenclature ought to follow this lead for consistency, and so we discourage the use of supercontinent names (e.g. Rodinian, Columbian) and regional phenomena, however exceptional. In this regard, we tentatively suggest that a new period (e.g. the 'Kratian'), could precede the Tonian as the first period of the Neoproterozoic Era and we concur with previous authors that the existing Siderian Period (named for banded iron formations) would fit better as a chronostratigraphically defined period of the terminal Archean. Indeed, all pre-Cryogenian subdivisions will need more conceptual grounding in any future chronostratigraphic scheme. We conclude that improved rock-based division of the Proterozoic Eon would likely comprise a threefold , period-level subdivision of the Paleoproterozoic Era (Oxygenian Rhyacian, Orosirian), a four-fold subdivision of the Mesoproterozoic Era (Statherian, Calymmian, Ectasian, Stenian) and potentially four-fold subdivision of the Neoproterozoic Era (pre-Tonian 'Kratian', Tonian, Cryogenian and Ediacaran). Future refinements towards an improved rockbased pre-Cryogenian geological time scale could be propoosed by new interna...

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“…Yukon-Alaska border region ( Fig. S1; Tables S1, S2; Young, 1982;Macdonald et al, 2018). This sample was collected along the Tatonduk River from a very coarse-grained and normal graded sublitharenite horizon interbedded with grey-black shale.…”

Section: J1119 Sample J1119 Is From the Ediacaran Upper Tindir Groupmentioning

confidence: 99%

“…Sample W7 is from the Ediacaran Gametrail Formation in the Wernecke inlier of eastern Yukon ( Fig. S1; Tables S1, S2; Macdonald et al, 2018). The sample was collected from the base of a well-sorted, medium-grained quartz arenite horizon with minor, shard-like lithic fragments.…”

Section: S1601 Sample S1601 Is From An Ediacaran Portion Of Undiffermentioning

confidence: 99%