Gigantic Ordovician volcanic ash fall in North America and Europe: Biological, tectonomagmatic, and event-stratigraphic significance

Huff, Warren D.; Bergström, Stig M.; Kolata, Dennis R.

doi:10.1130/0091-7613(1992)020<0875:govafi>2.3.co;2

Cited by 191 publications

(110 citation statements)

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“…However, as the tuffaceous component of the sediments is relatively small, there is no evidence of repeated smothering by ashfall. Furthermore, even major ashfalls do not necessarily result in the catastrophic death of the resident benthic marine fauna (Huff et al 1992). Volcanically-induced geochemical poisoning remains possible.…”

Section: B Amentioning

confidence: 99%

The depositional environment and taphonomy of the Homerian “Aulacopleura shales” fossil assemblage near Loděnice, Czech Republic (Prague Basin, Perunican microcontinent)

Hughes¹,

Kříž²,

Macquaker³

et al. 2014

Bull. Geosci.

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Excavation of Joachim Barrande's classic fossil locality of the "Aulacopleura shales" exposed on Na Černidlech Hill, near Loděnice reveals that most specimens were recovered from a 1.4 m interval exposed in "Barrande's pits". These are located at the eastern end of a 0.4 km trench dug in the mid 1800's to expose the interval along strike. Over an hundred bedding planes occur within the 1.4 m interval, and thousands of articulated trilobites have been collected at the site. Individual bed surfaces vary in the density, size, and taxonomic composition of the fossils contained. Some preserve a diverse benthic shelly fauna, others are almost exclusively dominated by the trilobite Aulacopleura koninckii, and a third variety is apparently barren of all shelly fossils. Isolated sclerites of A. koninckii are rare, and on almost all bedding surfaces exoskeletons are predominantly partially articulated and lack both alignment and sclerite fragmentation. The occurrence of A. koninckii conforms in many ways to the characteristics of a Type I trilobite lagerstätte of Brett et al. (2012). The presence of enrolled A. koninckii suggests that final burial may have resulted from relatively rapid obrution, although the condition of partial articulation indicates that many carcasses or exuviae partially disaggregated before burial. The mean size and density of A. koninckii specimens varies markedly among bedding planes, with some assemblages entirely comprised of juveniles, suggesting that notably dense trilobite clustering was not restricted only to reproductively mature individuals. The presence of multiple clusters of different mean specimen size partly accounts from the unusually comprehensive record of the articulated meraspid and holaspid ontogeny of this species at this locality. Limited bioturbation suggests a dysoxic substrate, and the olenimorphic form and distribution of A. koninckii, combined with a lack of encrustation or predation upon it, suggests that this species may have periodically bloomed in abundance at particular oxygen concentrations that largely excluded other skeletonized benthos. Some bedding plane assemblages might represent mass mortality events, perhaps as available oxygen passed below levels necessary to maintain the metabolism of A. koninckii. •

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Section: B Amentioning

confidence: 99%

The depositional environment and taphonomy of the Homerian “Aulacopleura shales” fossil assemblage near Loděnice, Czech Republic (Prague Basin, Perunican microcontinent)

Hughes¹,

Kříž²,

Macquaker³

et al. 2014

Bull. Geosci.

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“…For example, Ordovician volcanic ashes in the eastern North America and Western Europe represent one of the largest eruptions in Phanerozoic. This eruption produced a total of 1140 km 3 of dense-rock-equivalent with dispersal over several million square kilometers (Huff et al, 1992 Sr) i and high ε Nd values. Toba Tuffs in Sumatra, Indonesia, which are the largest eruption in Quaternary, cover an area of at least 4,000,000 km 2 and erupted~2500 km 3 dense-rock-equivalent of ignimbrite (Chesner, 2012).…”

mentioning

confidence: 99%

Triggers of Permo-Triassic boundary mass extinction in South China: The Siberian Traps or Paleo-Tethys ignimbrite flare-up?

Zhong

et al. 2014

Lithos

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“…If this extra-sedimentation of carbonates (compared to the Ordovician average) was not accompanied by an increment of the CO 2 degassing due to igneous and metamorphic activities, the lowering in CO 2 that seemingly accompanied the Hirnantian glaciation could broadly be estimated. This premise seems certainly adequate in view of the decline in volcanic activity described for the late Ordovician , after the important volcanic outgassing associated with eruption of Caradoc bentonites along the magmatic arc of eastern Laurentia [Huff et al, 1992[Huff et al, , 1993Lavoie, 1995]. Although a global evaluation of the whole Upper Ordovician carbonates recorded all over the world is beyond the scope of this work, we can propose a preliminary approximation by estimating the carbonate mass deposited during that time span in two key regions where the increment in carbonate sedimentation was particularly important : the northern Gondwana margin and Laurentia.…”

Section: The Late Ordovician Carbonate Sedimentationmentioning

confidence: 99%

The late Ordovician carbonate sedimentation as a major triggering factor of the Hirnantian glaciation

Villas

Vennin

Álvaro

et al. 2002

Bulletin De La Société Géologique De France

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Abstract. -A new approach explaining the main forcing factor of Hirnantian glaciation is proposed herein. It follows the models associating occurrences of continental glaciations with periods of low atmospheric CO 2 levels. The accumulation of great volumes of carbonates during pre-Hirnantian late Ordovician, in regions where these deposits were previously absent, is suggested as a major sink of atmospheric CO 2 . This would have caused an important lowering of the average temperature in the early Hirnantian, after CO 2 values had attained a certain threshold. This process was maintained by other positive feedbacks, such as the short-term carbonate weathering CO 2 sink. An increase of the direct flux of CO 2 from the atmosphere to the oceans by means of dissolution would have been driven by the enhancement of carbonate deposition. The great inundation of the low latitude Laurentia craton during Cincinnatian times and the establishment of a temperate-water carbonate sedimentation on the North Gondwana margin during pre-Hirnantian Ashgill allowed the burying of more than 840 × 10 15 kg (1.9 × 10 19 mol) of dissolved CO 2 . This mass is equivalent to nearly 350 times the present values of atmospheric CO 2 . This is important enough to have greatly altered the equilibrium between the CO 2 dissolved in the oceans and the partial pressure of CO 2 in the air, eventually causing an important reduction of the latter. The new model also offers a simple explanation for the end of the glaciation after a short time-span. Glacioeustatic lowering of the sea level, concomitant with the glaciation, would have stopped the extra-sedimentation of carbonate due to the retreat of the oceans from the platforms, closing this CO 2 sink. Pre-glacial CO 2 levels would then recover, due to volcanic and metamorphic CO 2 outgassing. After subsequent melting of the ice cap, oceanic circulation did not recover pre-Hirnantian Ashgill strength, resulting in a strong stratification of ocean waters and precluding the recovery of an extensive carbonate deposition. The well-known positive shift in the δ 13 C at the base of the Hirnantian is assumed to have been caused by weathering and dissolution of carbonates, relatively enriched in 13 C, during the glacioeustatic regression and exposure of the platforms.La sédimentation carbonatée ordovicienne : un des principaux facteurs déclencheur de la glaciation hirnantienneMots clés. -Carbonates, Glaciation, Puits de CO 2 , Hirnantien, Gondwana septentrional.Résumé. -Une nouvelle approche concernant le déroulement de la glaciation hirnantienne est proposée dans ce travail. Elle s'intéresse aux principaux facteurs clés de cette dernière et associe les effets d'une glaciation continentale à une pé-riode de bas niveau du CO 2 atmosphérique. L'accumulation d'un important volume de carbonates au cours de l'Ordovicien terminal pré-Hirnantien dans des régions où ces derniers étaient antérieurement absents est considérée comme un important puits de CO 2 atmosphérique. Cette accumulation pourrait être la cause d'une...

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Gigantic Ordovician volcanic ash fall in North America and Europe: Biological, tectonomagmatic, and event-stratigraphic significance

Cited by 191 publications

References 0 publications

The depositional environment and taphonomy of the Homerian “Aulacopleura shales” fossil assemblage near Loděnice, Czech Republic (Prague Basin, Perunican microcontinent)

The depositional environment and taphonomy of the Homerian “Aulacopleura shales” fossil assemblage near Loděnice, Czech Republic (Prague Basin, Perunican microcontinent)

Triggers of Permo-Triassic boundary mass extinction in South China: The Siberian Traps or Paleo-Tethys ignimbrite flare-up?

The late Ordovician carbonate sedimentation as a major triggering factor of the Hirnantian glaciation

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