Neoproterozoic snowball Earth under scrutiny: Evidence from the Fiq glaciation of Oman

Leather, Jonathan; Allen, Philip A.; Brasier, Martin D.; Cozzi, Andrea

doi:10.1130/0091-7613(2002)030<0891:nseuse>2.0.co;2

Cited by 145 publications

(73 citation statements)

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“…Two different initial conditions were tested: isolated snowball Earth (no ocean-atmosphere exchange) (28)(29)(30) and crevassed snowball Earth (limited oceanatmosphere exchange permitted) (31)(32)(33).…”

Section: Resultsmentioning

confidence: 99%

Dynamic model constraints on oxygen-17 depletion in atmospheric O ₂ after a snowball Earth

Cao

Bao

2013

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

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A large perturbation in atmospheric CO 2 and O 2 or bioproductivity will result in a drastic pulse of 17 O change in atmospheric O 2 , as seen in the Marinoan Oxygen-17 Depletion (MOSD) event in the immediate aftermath of a global deglaciation 635 Mya. The exact nature of the perturbation, however, is debated. Here we constructed a coupled, four-box, and quick-response biosphereatmosphere model to examine both the steady state and dynamics of the MOSD event. Our model shows that the ultra-high CO 2 concentrations proposed by the "snowball' Earth hypothesis produce a typical MOSD duration of less than 10 6 y and a magnitude of 17 O depletion reaching approximately −35‰. Both numbers are in remarkable agreement with geological constraints from South China and Svalbard. Moderate CO 2 and low O 2 concentration (e.g., 3,200 parts per million by volume and 0.01 bar, respectively) could produce distinct sulfate 17 O depletion only if postglacial marine bioproductivity was impossibly low. Our dynamic model also suggests that a snowball in which the ocean is isolated from the atmosphere by a continuous ice cover may be distinguished from one in which cracks in the ice permit ocean-atmosphere exchange only if partial pressure of atmospheric O 2 is larger than 0.02 bar during the snowball period and records of weathering-derived sulfate are available for the very first few tens of thousands of years after the onset of the meltdown. In any case, a snowball Earth is a precondition for the observed MOSD event. (3,(6)(7)(8)(9). Available data show that for the past 750 My, tropospheric O 2 has had a small magnitude of 17 O depletion, except for one unusual episode: the immediate aftermath of the Marinoan glacial meltdown at 635 Mya, when the Δ 17 O O2 probably reached values as negative as ∼−40‰ (6), compared with the −0.34‰ in today's atmospheric O 2 (10). An ultra-high pCO 2 condition was proposed to explain this Marinoan Oxygen-17 Depletion (MOSD) event (3, 6), which is consistent with the "snowball" Earth hypothesis that argues for a completely icecovered globe lasting several million years (11,12). However, it is not known if there are other potential atmosphere-biosphere scenarios that might produce distinctively negative Δ 17 O O2 , such as a condition in which pCO 2 is moderate but pO 2 and/or biosphere O 2 flux are low, as proposed recently in an effort to reconcile organic and inorganic carbon isotope data from the postglacial cap carbonates (13). It therefore is imperative to examine the Δ 17 O O2 variability among geologically reasonable scenarios. Previous modeling studies on Δ 17 O O2 vary the ratio of pO 2 /pCO 2 , but with a fixed O 2 residence time, or focus on steady state without considering dynamic evolution of pO 2 , pCO 2 , or O 2 production fluxes (3, 13) or consider only minor Δ 17 O O2 difference between recent glacial and interglacial periods (14). In addition, a critical piece of information, the evolution of pO 2 before and after the meltdown of the most severe global glaciation in Earth history, w...

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Section: Resultsmentioning

confidence: 99%

Dynamic model constraints on oxygen-17 depletion in atmospheric O ₂ after a snowball Earth

Cao

Bao

2013

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

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“…NE Svalbard, Fairchild & Hambrey 1984;West African Craton, Deynoux 1985). Many sections show evidence of phases of relative ice advance and retreat (Spencer 1971;Lindsay 1989;Leather et al 2002). Close analogies with modern glacial environments of various thermal regimes have been suggested: ranging from high sedimentation rates of the Neogene glacimarine Gulf of Alaska setting (Eyles & Eyles 1983), to ice-stream-fed ice shelves of parts of the modern Antarctic margin (Moncrieff & Hambrey 1990;Fig.…”

Section: Glacial Deposits In Neoproterozoic Sedimentary Basinsmentioning

confidence: 99%

“…For example, the strong positive feedback inherent in the albedo driver proposed in the Snowball Earth model should produce a rapid-in and rapid-out monotonic stratigraphic record lacking the high-frequency sea-level variation characteristic of the more delicately balanced feedbacks acting in the Quaternary. The seemingly abrupt and synchronous termination of the Marinoan glaciation (Condon et al 2005) in China and Namibia would suggest this difference, whereas the repeated alternations of glacial and non-glacial facies reported in some Neoproterozoic formations would stress the similarity to the Quaternary (Condon et al 2002;Leather et al 2002;Arnaud & Eyles 2006). In their overview of Neoproterozoic glacial deposits, Etienne et al (2007) found that the styles of preservation of glacial facies can all be matched with Phanerozoic examples and that there are no characteristics requiring extreme frigidity.…”

Section: Glacial Deposits In Neoproterozoic Sedimentary Basinsmentioning

confidence: 99%

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Neoproterozoic glaciation in the Earth System

Fairchild

Kennedy

2007

JGS

216

116

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The Neoproterozoic contains severe glacial intervals (750–580 Ma) including two extending to low palaeomagnetic latitudes. Paucity of radiometric dates indicates the need for chronostratigraphic tools. Whereas the marine 87 Sr/ 86 Sr signatures show a steady rise, δ 13 C fluctuates, the most reproducible variations being negative signatures in carbonate caps to glacial units, but more diagenetic work is needed. Four conceptual models for the icehouse conditions are contrasted: Zipper-Rift Earth (diachronous glaciation related to continental rift margins), High-tilt Earth (high-obliquity and preferential low-latitude glaciation), Snowball Earth (extreme glaciation related to runaway ice–albedo feedback) and Slushball Earth (coexistence of unfrozen oceans and sea-level glaciers in the tropics). Climate models readily simulate runaway glaciation, but the Earth may not be able to recover from it. The Slushball state requires more extensive modelling. Biogeochemical models highlight the lack of CO 2 buffering in the Neoproterozoic and the likely transition from a methane- to a CO 2 -dominated climate system. Relevant processes include tropical weathering of volcanic provinces, and new land biotas stimulating both clay mineral formation and P delivery to the oceans, facilitating organic C burial. Hence a step change in the Earth System was probably both facilitated by organisms and responsible for moderating Phanerozoic climate.

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“…Both early and late Cryogenian glaciations, referred to as the Sturtian and Marinoan (based on locations in South Australia), respectively, appear to be globally distributed (Li et al, 2013). In some regions, the history of one or both glaciations is locally or regionally complex, with distinct glacial retreat intervals recognized in South Australia (Williams et al, 2008, Le Heron et al, 2011Rose et al, 2013), Namibia (Hoffman, 2011;Le Heron et al, 2013), Scotland (Spencer, 1971;Arnaud and Fairchild, 2011) and Oman (Leather et al, 2002;Rieu et al, 2007a). However, semi-continuous Cryogenian successions display a clear stratigraphic motif in which two glacial units bound an unambiguously non-glacial interval, representing a mid-Cryogenian interlude of unknown duration (~5-27 My; Rooney et al, 2014).…”

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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Neoproterozoic snowball Earth under scrutiny: Evidence from the Fiq glaciation of Oman

Cited by 145 publications

References 6 publications

Dynamic model constraints on oxygen-17 depletion in atmospheric O ₂ after a snowball Earth

Dynamic model constraints on oxygen-17 depletion in atmospheric O ₂ after a snowball Earth

Neoproterozoic glaciation in the Earth System

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

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Neoproterozoic snowball Earth under scrutiny: Evidence from the Fiq glaciation of Oman

Cited by 145 publications

References 6 publications

Dynamic model constraints on oxygen-17 depletion in atmospheric O 2 after a snowball Earth

Dynamic model constraints on oxygen-17 depletion in atmospheric O 2 after a snowball Earth

Neoproterozoic glaciation in the Earth System

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

Contact Info

Product

Resources

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Dynamic model constraints on oxygen-17 depletion in atmospheric O ₂ after a snowball Earth

Dynamic model constraints on oxygen-17 depletion in atmospheric O ₂ after a snowball Earth