Mississippian reef development in the Cracoe Limestone Formation of the southern Askrigg Block, North Yorkshire, UK

A detailed biostratigraphy is established, using the high foraminiferal abundance and diversity at Trowbarrow Quarry, which is also proposed as a stratotype section for the late Asbian (late Visean), a substage not previously formally subdivided. The foraminiferal assemblages suggest that the early Asbian has to be revised, which has implications for the chronostratigraphy of many late Visean outcrops in Britain, which are probably erroneously interpreted. From the upper part of the Park Limestone Formation at Trowbarrow Quarry, near the base of the section, the transition between foraminifers assigned to the early and late Asbian (Cf6α–β to Cf6γ subzones) is identified. The Urswick Limestone Formation contains excellent biostratigraphic records of many important taxa, enabling the subdivision of the formation into five foraminiferal assemblage zones for the late Asbian, namely Cf6γ1a, Cf6γ1b, Cf6γ2a, Cf6γ2b and Cf6γ2c. The last assemblage is currently recognized only in the North Pennines and at Trowbarrow. These assemblages enable revision of the stratigraphic range of many taxa used as biostratigraphic markers in Britain and Ireland. Owing to its excellent foraminiferal record, the late Asbian subdivisions will significantly facilitate the reinterpretation of other well‐known Asbian platform carbonate successions in Britain. Although there are some faunal differences, the base of the late Asbian can be confidently correlated to other European zonal schemes, with its base being equivalent to the base of the former V3bγ or more recent MFZ14 foraminiferal zones of Belgium, and the base of the Mikhailovian Substage in Russia.

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“…1991; Waters et al . 2017 b ) and other authors claiming its first occurrence in the Cf6γ2 assemblage (Jones & Somerville 1996; Somerville 2008).…”

Section: Biozonation and Analysismentioning

confidence: 89%

A late Asbian (Mississippian) stratotype for England: Trowbarrow Quarry, Cumbria, UK

Cózar

Somerville

Hounslow

et al. 2022

Papers in Palaeontology

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“…While in Vachard (1974), the markers for the V3bγ supérieur were Bradyina rotula, Neoarchaediscus and common Endothyranopsis. Unfortunately, Howchinia is rather poorly represented in Britain during the Asbian in shallow-water platform facies, as well as Euxinita (e.g., Waters et al 2017a), although they are more common in the deeper-water Cracoan mud mound facies (Waters et al 2017b). On the other hand, Bradyina is a strongly facies-controlled taxon, and in many cases, it first occurs close to the Asbian-Brigantian boundary interval or just above the boundary in the basal Brigantian.…”

Section: Asbianmentioning

confidence: 99%

Foraminifers in upper Viséan–lower Serpukhovian limestones (Mississippian) from South Wales: regional correlation and implications for British foraminiferal zonal schemes

Cózar

Somerville

2020

PYGS

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Foraminiferal assemblages have been recorded in sections from the Gower Peninsula and North Crop in South Wales, of Holkerian (Stormy Limestone Formation), late Asbian to early Brigantian (Oxwich Head Limestone Formation) and uppermost early to late Brigantian (Oystermouth Formation) age. The absence of lower Asbian foraminifers in the studied successions is confirmed. These formations and biostratigraphic boundaries are correlated with those in northern England, where similar foraminiferal assemblages are recorded.It is considered that Loeblichia paraammonoides does not occur in Wales. Its record is based on a misidentification of L. ammonoides and its presence in Britain is questioned. The distribution of Bibradya in Britain seems to be restricted to the late Asbian. Archaediscus at angulatus stage and ancestral forms of Palaeotextularia are confirmed in the uppermost Holkerian. Ancestral forms of Koskinobigenerina and Climacammina recorded below the upper Asbian and lower Brigantian, respectively, are considered to be misidentifications. Archaediscus at tenuis stage recorded from the Oystermouth Formation can form a plausible marker for the equivalent Three Yard Limestone and Four Fathom Limestone members in northern England. The acme of discoidal archaediscids is equivalent to the Four Fathom Limestone Member. In contrast to a ready comparison with foraminiferal microfaunas from northern England, comparison with North Wales is problematic. Nevertheless, it would appear that most assemblages previously cited as early Asbian, would now likely be reassigned to the late Asbian, similar to the observations in South Wales.

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“…This type of facies is rather abundant in many other mound complexes (e.g. Bridges & Chapman, 1988;Pickard, 1992;Somerville et al, 1992Somerville et al, , 1996Waters et al, 2017), and facilitated the reconstructions of the surrounding environments to the buildups. The virtual absence of this type of facies in the Montagne Noire suggests that the buildups were growing directly on the shales and siltstones ( Fig.…”

Section: Reconstructions Of the Platformmentioning

confidence: 99%

“…(e.g. Lees & Miller, ; Della Porta et al ., ; Rodríguez‐Martínez et al ., ; Waters et al ., ), although breccias of the Montagne Noire are commonly poorly exposed which complicate its interpretation.…”

Section: Environmental Parametersmentioning

confidence: 99%

Environmental controls on the development of Mississippian microbial carbonate mounds and platform limestones in southern Montagne Noire (France)

Cózar

Izart²,

Somerville

et al. 2019

Sedimentology

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Late Mississippian carbonates in southern Montagne Noire are dominantly domical to laterally‐accreted microbial mounds in some formations, as well as stratiform microbial limestones occurring in hundreds of olistoliths within a flysch basin, constituting pieces of a giant puzzle that are used to help reconstruct a platform in a region that is no longer preserved. Petrographic data of limestone samples from 14 continuous long sections of olistoliths have been analyzed statistically, using multivariate clustering (Q‐mode) of the components/matrix/cement and canonical correspondence analysis that allow the reconstruction of the environmental parameters of carbonate microbial communities in space and time. Clustering analysis separated microbial and non‐microbial facies. The calculation of indices along the various axes from canonical correspondence analysis allows recognition of the controlling factors of the mounds and microbial growth as being turbidity, light penetration, bathymetry and storms. Turbidity and light penetration are the primary factors controlling the morphology of the microbial limestones. Representation of the light penetration and bathymetry indices on the stratigraphical sections defines two vertical environmental gradients. Light penetration can be subdivided into euphotic, euphotic–dysphotic and dysphotic‐aphotic conditions. The representation of the bathymetry allows the subdivision of samples into a deeper outer ramp, external mid‐ramp and internal mid‐ramp. The curve distance from the section base = f (index) suggests a cyclicity for the platform that cannot be compared with the onlap curve defined from other cratonic areas (Moscow Basin), and thus the cyclic succession of the Montagne Noire is interpreted to have been mostly tectonically‐controlled. Integration of the data allowed the reconstruction of the original Mississippian carbonate platform, where, up to the Mikhailovian, it appears to correspond to a platform morphology, with narrow shallow water facies and wide turbiditic systems, whereas the width of shallow‐water settings expanded during the Venevian to the Protvian, forming a ramp or distally‐steepened ramp with widespread microbial limestones.

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Mississippian reef development in the Cracoe Limestone Formation of the southern Askrigg Block, North Yorkshire, UK

Abstract: Abstract:The southern margin of the Askrigg Block around Cracoe, North Yorkshire, shows

Cited by 16 publications

References 40 publications

A late Asbian (Mississippian) stratotype for England: Trowbarrow Quarry, Cumbria, UK

A late Asbian (Mississippian) stratotype for England: Trowbarrow Quarry, Cumbria, UK

Foraminifers in upper Viséan–lower Serpukhovian limestones (Mississippian) from South Wales: regional correlation and implications for British foraminiferal zonal schemes

Environmental controls on the development of Mississippian microbial carbonate mounds and platform limestones in southern Montagne Noire (France)

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