Iron-rich carbonate tidal deposits, Angepena Formation, South Australia: A redox-stratified Cryogenian basin

O’Connell, Brennan; Wallace, Malcolm W.; Hood, Ashleigh v.S.; Lechte, Maxwell A.; Planavsky, Noah J.

doi:10.1016/j.precamres.2020.105668

Cited by 16 publications

(3 citation statements)

References 137 publications

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“…Iron oxide‐rich lithologies are present in all units of the Trezona Formation (from deep water to shallow water), suggesting iron oxidation in both shallow and subtidal conditions. This is consistent with other evidence for ferruginous ocean conditions and fluctuating redox conditions in this Cryogenian basin (Hood & Wallace, 2014; O'Connell et al, 2020) and elsewhere during the Cryogenian (Canfield et al, 2007). We tentatively suggest a chemocline largely situated in deep water around the outer ramp setting.…”

Section: Discussionsupporting

confidence: 91%

Deep water cuspate stromatolites of the Cryogenian Trezona Formation

et al. 2021

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Stromatolites and microbialites contain a rich repository of environmental and biological information. Despite extensive research, questions remain regarding the biological, chemical, and physical processes that control stromatolite macro, meso, and microstructure. We report unusual deep water cuspate stromatolites from the Cryogenian Trezona Formation, South Australia, from a mixed siliciclastic–carbonate open marine ramp setting. Cuspate stromatolite horizons develop near the base of decameter‐scale transgression–regression cycles and typically overlie decimeter‐scale irregular erosion surfaces. The cuspate structure within the stromatolites form near vertical, stacked cusp structures in cross section. In plan view, the cusps form cm‐scale sharp parallel ridges oriented perpendicular to the regional downslope direction and perpendicular to the elongation direction of stromatolites. Stromatolites colonized topographic highs of irregular erosion surfaces (often hardgrounds) and grew in carbonate supersaturated, iron‐rich marine waters in low turbidity sediment‐starved settings. Cuspate stromatolites are interpreted as forming in deep water environments during maximum transgression as condensed intervals. Their microbial metabolism may require low light and low oxygen. A deep water origin for the Trezona Formation cuspate stromatolites and other Precambrian cuspate stromatolites suggests a link between the cuspate morphology and physical/chemical (carbonate supersaturated, low light, and low oxygen) conditions of Precambrian deep water marine settings.

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Section: Discussionsupporting

confidence: 91%

Deep water cuspate stromatolites of the Cryogenian Trezona Formation

et al. 2021

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“…Ce anomalies can respond to redox changes over metre scales [35], although in the open ocean, local signals may be overprinted by basin-wide signals due to slow kinetics [29] (table 1). The magnitude of any Ce anomaly may correspond to the concentration of oxygen or the thickness of the oxic layer, but can also be influenced by other factors such as local Mn oxide fluxes [36]. Rare earth elements, and associated Ce anomalies, substitute for Ca 2+ in the carbonate mineral lattice, and as such, can faithfully record seawater rare earth elements at the site of carbonate formation and are relatively robust to diagenesis and even dolomitization [30,37].…”

Section: Cerium Anomaliesmentioning

confidence: 99%

Reconciling proxy records and models of Earth's oxygenation during the Neoproterozoic and Palaeozoic

Tostevin

Mills

2020

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A hypothesized rise in oxygen levels in the Neoproterozoic, dubbed the Neoproterozoic Oxygenation Event, has been repeatedly linked to the origin and rise of animal life. However, a new body of work has emerged over the past decade that questions this narrative. We explore available proxy records of atmospheric and marine oxygenation and, considering the unique systematics of each geochemical system, attempt to reconcile the data. We also present new results from a comprehensive COPSE biogeochemical model that combines several recent additions, to create a continuous model record from 850 to 250 Ma. We conclude that oxygen levels were intermediate across the Ediacaran and early Palaeozoic, and highly dynamic. Stable, modern-like conditions were not reached until the Late Palaeozoic. We therefore propose that the terms Neoproterozoic Oxygenation Window and Palaeozoic Oxygenation Event are more appropriate descriptors of the rise of oxygen in Earth's atmosphere and oceans.

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“…14), which is reflected in the reddish color characteristic of oxidized iron (Fig. 4A; O'Connell et al, 2020).…”

Section: Trace Elements and Facies Interpretationsmentioning

confidence: 99%

Geochemical investigation of the late Ordovician Bighorn Dolomite of western Wyoming

James¹

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Iron-rich carbonate tidal deposits, Angepena Formation, South Australia: A redox-stratified Cryogenian basin

Cited by 16 publications

References 137 publications

Deep water cuspate stromatolites of the Cryogenian Trezona Formation

Deep water cuspate stromatolites of the Cryogenian Trezona Formation

Reconciling proxy records and models of Earth's oxygenation during the Neoproterozoic and Palaeozoic

Geochemical investigation of the late Ordovician Bighorn Dolomite of western Wyoming

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