The Longmyndian Supergroup and related Precambrian sediments of England and Wales

Pauley, J. C.

doi:10.1007/978-94-009-0401-9_2

Cited by 7 publications

(5 citation statements)

References 35 publications

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“…A lapilli tuff at the base of the Stretton Shale Formation has been dated at 566.6 ± 2.9 Ma and another from within the Longmyndian succession at the base of the Lightspout Formation at 555.9 ± 3.5 were dated by Compston, Wright & Toghill (2002). It has also recently been proposed that the Wentnor Group is unconformable on the Stretton Group (Compston, Wright & Toghill, 2002), but no new evidence was presented and is not reconcilable with our field observations (Pauley, 1990(Pauley, , 1991McIlroy & Horák, in press). The Uriconian is, however, in unconformable contact with the overlying Wrekin Quartzite, which is estimated at about 530 Ma, with the local marine Cambrian * Author for correspondence: dmc@esd.mun.ca transgression thus being estimated as spanning 520-530 Ma (Wright et al 1993).…”

Section: Introductioncontrasting

confidence: 82%

“…Elsewhere, structures resembling these types have been recorded from around the world from Neoproterozoic (Ediacaran) strata and ascribed to various body and trace fossil taxa including Beltanelliformis, Intrites, Medusinites, Nemiana, Sekwia and Vendella (Palij, 1976;Palij, Posti & Fedonkin, 1979;Fedonkin, 1981Fedonkin, , 1983Fedonkin, , 1985Hofmann, Fritz & Narbonne, 1983;Bekker, 1985;Gureev, 1987;Narbonne & Hofmann, 1987). Similar Pauley, 1990). Black areas on the inset map (a) represent the Neoproterozoic-Cambrian outcrops of England and Wales.…”

Section: Introductionmentioning

confidence: 88%

“…(a) The part of the Burway Formation in which some of the structures were found has been shown on Pauley, 1990). detailed sedimentological evidence (J. C. Pauley, unpub.…”

Section: The Nature Of the Supposed Organic Structuresmentioning

confidence: 99%

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Fossils and matgrounds from the Neoproterozoic Longmyndian Supergroup, Shropshire, UK

McIlroy

Crimes

Pauley³

2005

Geol. Mag.

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Body and trace fossils of Ediacaran affinity are described from strata of the late Neoproterozoic Longmyndian Supergroup exposed near Church Stretton, Shropshire, UK. The almost spherical soft-bodied Ediacaran fossil Beltanelliformis brunsae Menner occurs rarely in the Burway Formation, but much smaller, simpler, discoidal structures are common in both the Burway and Synalds formations and are referred to Beltanelliformis minutae sp. nov. Similar discoidal structures, but with a distinct central depression, are included in Intrites punctatus Fedonkin and are common at several horizons. Two blocks with numerous examples of Medusinites aff. asteroides (Sprigg) Glaessner & Wade were recovered from the Burway Formation. The purported Ediacaran body fossil ‘Arumberia’ Glaessner & Walter is common at several horizons but its biogenicity is not accepted herein. ‘Arumberia’ is thus treated along with evidence for microbially bound sediment surfaces or matgrounds that have been suggested by several authors to be necessary for some types of Ediacaran preservation. The assemblage of simple trace and body fossils along with matgrounds is typical of latest Neoproterozoic time, though some elements range into the Phanerozoic.

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Section: Introductioncontrasting

confidence: 82%

Section: Introductionmentioning

confidence: 88%

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Fossils and matgrounds from the Neoproterozoic Longmyndian Supergroup, Shropshire, UK

McIlroy

Crimes

Pauley³

2005

Geol. Mag.

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“…Coeval sedimentary successions that are dominated by volcanogenic turbidites are locally associated with these arcrelated magmatic rocks, and have been attributed to deposition in a variety of intra-arc, interarc and back arc basins (e.g., Pe-Piper and Murphy 1989;Pauley 1990;Smith and Socci 1990;O'Brien et al 1996;Murphy et al 1999). This magmatic activity and the generation of arc-related basins are interpreted to reflect oblique subduction beneath the northern Gondwanan margin.…”

Section: Geologic Settingmentioning

confidence: 99%

Neoproterozoic?Early Paleozoic evolution of peri-Gondwanan terranes: implications for Laurentia-Gondwana connections

Murphy

Pisarevsky

Nance

et al. 2004

Int J Earth Sci (Geol Rundsch)

270

134

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Neoproterozoic tectonics is dominated by the amalgamation of the supercontinent Rodinia at ca. 1.0 Ga, its breakup at ca. 0.75 Ga, and the collision between East and West Gondwana between 0.6 and 0.5 Ga. The principal stages in this evolution are recorded by terranes along the northern margin of West Gondwana (Amazonia and West Africa), which continuously faced open oceans during the Neoproterozoic. Two types of these so-called peri-Gondwanan terranes were distributed along this margin in the late Neoproterozoic: (1) Avalonian-type terranes (e.g.

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“…1) are defined by their Neoproterozoic evolution on an active continental margin, and by the peri-Gondwanan "Acado-Baltic" fauna of their shallow-marine Cambro-Ordovician overstep sequences (e.g., Rast and Skehan, 1983;Murphy and Nance, 1989;Nance et al, 1991). They include (1) the Avalon composite terrane of New England and Atlantic Canada (e.g., O'Brien et al, 1983;Nance, 1986;, referred to as "West Avalonia"; (2) the predrift continuation of this terrane in southern Britain (e.g., Thorpe et al, 1984;Pharoah et al, 1987;Pauley, 1990a), referred to as "East Avalonia"; and (3) the North Armorican composite terrane in the Cadomian orogenic belt of northwestern France and Bohemia (e.g., Chaloupsky, 1990;Dupret et al, 1990;Rabu et al, 1990;Egal et al, this volume;Strachan et al, this volume), referred to as "Cadomia. "…”

Section: Tectonic Setting Of the Avalonian-cadomian Orogenic Beltmentioning

confidence: 99%

Basement isotopic signatures and Neoproterozoic paleogeography of Avalonian-Cadomian and related terranes in the Circum-North Atlantic

Nance¹,

Murphy²

1996

Special Paper 304: Avalonian and Related Peri-Gondwanan Terranes of the Circum-North Atlantic

118

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Avalonian-Cadomian and related terranes of the circum-North Atlantic constitute portions of an accretionary orogen that developed on an active Gondwanan margin at the periphery of the Neoproterozoic supercontinent Vendia. As a peripheral orogenic belt lying oblique to adjacent cratonic age provinces and the interior collisional orogenic sutures associated with supercontinent assembly, its component terranes are likely to have evolved upon different cratonic basements. Available Nd isotopic data and U-Pb detrital zircon ages support this contention and suggest that West Avalonia, Carolina, and Florida lay adjacent to the Amazonian craton during the Neoproterozoic, whereas Cadomia, Spain, and portions of East Avalonia occupied positions adjacent to the West African craton.Neodymium isotopic compositions for crustally derived felsic rocks from each of these peri-Gondwanan terranes are typical of the upper crust (Sm/Nd ≈ 0.19). However, initial ε Nd values for West Avalonia are strongly positive with 1.1-0.8 Ga depleted mantle model ages, whereas those for Cadomia are predominantly negative and yield crustal residence ages of 1.9-1.0 Ga. Nd evolution diagrams for West Avalonia show little overlap with those for Cadomia (suggesting basements of contrasting isotopic characteristics) but closely match those of the Tocantins Province that borders the Amazonian craton in Central Brazil. A peri-Amazonian position for West Avalonia is also suggested by detrital zircon data from Neoproterozoic metasedimentary units that match all age provinces of the Amazonian craton. By contrast, Nd isotopic data for Cadomian basement (ca. 2.0 Ga Icart Gneiss) closely resemble those for 2.1-2.0 Ga (Eburnian) granitoids in West Africa. Basement of similar isotopic characteristics to that of Cadomia also provided the source for Cambrian sedimentary rocks in the Meguma terrane that contain detrital zircons that match each of the age provinces of the West African craton. East Avalonia shows Nd isotopic affinities with both West Avalonia and Cadomia and may straddle a suture between their respective basements. Zircon ages and Nd isotopic data for Carolina and the Florida subsurface (Suwannee terrane) also show similarities with those for West Avalonia but suggest a more evolved crustal component of possible Grenville age, supporting their derivation from more westerly present-day peri-Amazonian positions.Such variations in basement isotopic signatures provide important constraints for Neoproterozoic paleogeographic reconstruction of the now-dismembered AvalonianCadomian orogenic belt and may be of more general application to the palinspastic restoration of dispersed Precambrian terranes.

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The Longmyndian Supergroup and related Precambrian sediments of England and Wales

Cited by 7 publications

References 35 publications

Fossils and matgrounds from the Neoproterozoic Longmyndian Supergroup, Shropshire, UK

Fossils and matgrounds from the Neoproterozoic Longmyndian Supergroup, Shropshire, UK

Neoproterozoic?Early Paleozoic evolution of peri-Gondwanan terranes: implications for Laurentia-Gondwana connections

Basement isotopic signatures and Neoproterozoic paleogeography of Avalonian-Cadomian and related terranes in the Circum-North Atlantic

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