Ooid-stromatolite association as a precursor of bioevents (Silurian, Timan–northern Ural Region)

Антошкина, А. И.

doi:10.1016/j.palwor.2014.11.007

Cited by 11 publications

(2 citation statements)

References 16 publications

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“…The broad occurrence of microbial carbonates (Calner 2005a) is represented by open-marine stromatolites (Cherns 1982, Calner 2005c, Antoshkina 2014) and the mass occurrence of oncoids (WigforssLange 1999, Samtleben et al 2000, Arp et al 2001, Calner 2005c, Jeppsson et al 2007, Brett et al 2009, Kozłowski & Munnecke 2010. The event interval contains unusual, globally widespread appearances of oolites (Stel & de Coo 1977, Kozłowski 2003, Calner 2005c, Jeppsson et al 2007, Wigforss-Lange 2007, Eriksson & Calner 2008, Barrick et al 2010.…”

Section: Outline Of the Kozlowski/lau Event Recordmentioning

confidence: 99%

Eolian dust influx and massive whitings during the kozlowski/Lau Event: carbonate hypersaturation as a possible driver of the mid-Ludfordian Carbon Isotope Excursion

Kozłowski¹

2015

Bull. Geosci.

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The mid-Ludfordian Carbon Isotope Excursion (CIE) is one of the biggest perturbation in the isotope and facies record in the Palaeozoic. However, its causes still remain unknown. In the periplatform setting of the Baltica palaeocontinent the event interval contains rock-forming minute calcite crystals, interpreted here as suspension-originated analogues of recent whitings and calcite rafts. The grains were preferentially formed around picocyanobacterial filaments, which are preserved as tubes inside. An event-related, 9 m-thick, massive calcisiltite bed points to the persistent hypersaturated state conditions (HSS) during the increasing limb of the CIE. The studied interval contains also a significant admixture of minute-sized detrital dolomite grains, appear for the first time several meters below and reach peak abundance immediately below the calcisiltite interval. The dolomite grains show consistent δ 13 C values (~0‰) across the CIE. Their record is decoupled from the bulk-rock C-isotope record and thus indicates overwhelmingly pre-sedimentary formation and extrabasinal provenance of the dolomite. The size and provenance of the grains, along with their incorporation into surface water precipitates and formation of specific very thin laminas with internal density gradation of grains (dolomite-quartz couplets), suggest the eolian delivery of the grains to the basin. The dust influx pulses seem to have triggered the calcite precipitation events. Furthermore, the size-frequency distribution of the pyrite framboids across the studied interval shows that the progressing dust influx was followed by persistent euxinia occurring right before and during the increasing limb of the CIE. In the proposed model, globally enhanced eolian delivery of iron during the assumed glaciation promoted high net pyrite formation. The resulting "sulphate to bicarbonate exchange", a hypothetical dissolution of eolian carbonate dust particles in deep basins, a concurrent bicarbonate supply from the carbonates emerged due to the sea-level fall, and a parallel cessation of the carbonate factory (exposed carbonate platform tops), raised the alkalinity and formed the global carbonate hypersaturated state (HSS) of the ocean. The processes needed largescale invasion of the CO 2 , consumed in the ocean by bicarbonate formation processes. It is hypothesized that during the subsequent initial transgression, the HSS was discharged by massive carbonate precipitation. The rapid "carbonate reflux" returned the earlier uptaken CO 2 to the atmosphere by fast degassing. Its fast transfer resulted in the globally synchronized, kinetic, residual, 13 C DIC -enrichment of water pools localized over individual carbonate platforms. During "carbonate reflux", the local CIE amplitude depended on the carbonate production rate, water column thickness and pool residence time.•

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Section: Outline Of the Kozlowski/lau Event Recordmentioning

confidence: 99%

Eolian dust influx and massive whitings during the kozlowski/Lau Event: carbonate hypersaturation as a possible driver of the mid-Ludfordian Carbon Isotope Excursion

Kozłowski¹

2015

Bull. Geosci.

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“…Similar to the previous facies association, the shoal bar association seems to record the alternation between low energy and occasional high energy sedimentation pulses. Low–moderate energy deposits are represented by small cross‐stratifications, well‐sorted ooids and giant ooids of facies 4, which indicate prolonged sediment reworking in a wave swept shallow shoal, possibly influenced by tidal currents and intra‐lagoonal circulation (Lehrmann et al ., 2012; Antoshkina, 2015; Thorie et al ., 2018). Massive oncoid–stromatolite boundstones (f5), however, were likely deposited by episodic high energy events (storms and abnormal high tides), which were powerful enough to erode bio‐construction fragments from neighbouring reefal stromatolite buildups (cf.…”

Section: Discussionmentioning

confidence: 99%

Sedimentary evolution and sequence stratigraphy of Ediacaran high‐grade phosphorite–dolomite–shale successions of the Bocaina Formation (Corumbá Group), Central Brazil: Implications for the Neoproterozoic phosphogenic event

et al. 2023

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Extensive phosphorite deposition is observed in the Neoproterozoic after a prolonged hiatus during most of the Mesoproterozoic era. This event is thought to represent an important record of major palaeoenvironmental, palaeoceanographic and biotic changes that shaped Neoproterozoic ecosystems, suggesting close relationships between phosphogenesis and the preservation of key Ediacaran biotas. However, high‐grade Ediacaran phosphorite deposits are relatively uncommon, diminishing the opportunity to test current phosphate mineralization–deposition models and their implications for Neoproterozoic research. In this scenario, widespread Ediacaran phosphorite–dolomite–shale successions of the Bocaina Formation (Corumbá Group – Central Brazil) are poorly explored in international literature. Nevertheless, recent advances in phosphate exploration gave access to continuous drill core sections and freshly opened mine pits, revealing an unprecedented record of complex phosphatic successions featuring the occurrence of Ediacaran microfossils assigned to the Doushantuo–Pertatataka assemblages. This work seeks to constrain main lithofacies, sequence stratigraphy and depositional settings from these phosphatic successions in order to analyse the sedimentary evolution of the unit under the current Neoproterozoic phosphorite research framework. These results indicate that the Bocaina Formation records secular sustained phosphate deposition. These deposits are related to unprecedented, microbialite reef rim phosphorites deposited during a lower accretionary rimmed platform stage, followed by the deposition of Doushantuo‐like, whole platform phosphorites associated with a later, drowned platform stage, therefore, reinforcing the evidence for the operation of strong allogeneic controls on phosphate mineralization–concentration. In addition, this study concludes that fossiliferous Ediacaran phosphatic deposits such as the Bocaina Formation are important to understanding Neoproterozoic phosphogenic events, because they may record the transition from a Precambrian to Phanerozoic‐like phosphogenesis associated with the instauration of the Ediacaran–Cambrian phosphatic taphonomic window. This evidence hints that the growing dataset from the Bocaina Formation may bring new, exciting perspectives for Neoproterozoic research as a whole.

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Comparative study of two relatives, MISS and Stromatolites: example from the Proterozoic Kunihar Formation, Simla Group, Lesser Himalaya

Mukhopadhyay

Thorie

2016

Arab J Geosci

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Ooid-stromatolite association as a precursor of bioevents (Silurian, Timan–northern Ural Region)

Cited by 11 publications

References 16 publications

Eolian dust influx and massive whitings during the kozlowski/Lau Event: carbonate hypersaturation as a possible driver of the mid-Ludfordian Carbon Isotope Excursion

Eolian dust influx and massive whitings during the kozlowski/Lau Event: carbonate hypersaturation as a possible driver of the mid-Ludfordian Carbon Isotope Excursion

Sedimentary evolution and sequence stratigraphy of Ediacaran high‐grade phosphorite–dolomite–shale successions of the Bocaina Formation (Corumbá Group), Central Brazil: Implications for the Neoproterozoic phosphogenic event

Comparative study of two relatives, MISS and Stromatolites: example from the Proterozoic Kunihar Formation, Simla Group, Lesser Himalaya

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