Acritarchs, miospores and correlation of the Ludlovian-Downtonian and Silurian-Devonian boundaries

Richardson, John B.; Rasul, Syed M.; Al-Ameri, Thamer K.

doi:10.1016/0034-6667(81)90039-7

Cited by 48 publications

(27 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…- Table 1. 380 d. edwards and j. b. richardson silurian and lower devonian plant assemblages Richardson et al (1981) approached the problem of the first two boundaries by attempting to relate acritarchs and spores, and later chitinozoans and spores in the Welsh Borderland and Cantabrian Mountains to those of Podolia where, unlike the Klonk sucession, the first appearances of Monograptus uniformis uniformis and M. uniformis angustidens are not coeval. The stratotype sequence in the Czech Republic (Klonk) has yielded only poor palynomorphs (Richardson 1984) apart from chitinozoans.…”

Section: Spores/ Invertebratesmentioning

confidence: 99%

“…The detailed descriptions of the taxa leading to the identification and nomenclature of the species and hence to the definition of the spore assemblage zone will be published elsewhere. The presence of Turinia pagei, with pre-MN Zone spores of the Apiculiretusispora spE Zone (Richardson et al 1981 below the top of the Raglan Mudstone Formation means that the base of the Devonian is at least 33 m below the base of the St Maughans Formation. In the Podolian sections, pre-MN spore assemblages, in an equivalent position to the Apiculiretusispora spE Zone, occur above the graptolite Monograptus uniformis var.…”

Section: Spores/ Invertebratesmentioning

confidence: 99%

See 1 more Smart Citation

Silurian and Lower Devonian plant assemblages from the Anglo‐Welsh Basin: a palaeobotanical and palynological synthesis

Edwards

Richardson

2004

Geological Journal

Self Cite

View full text Add to dashboard Cite

A comprehensive survey of plant assemblages from Upper Silurian (Gorstian-Pȓídolí) and Lower Devonian (LochkovianPragian) localities in South Wales and the Welsh Borderland is presented, together with some comments on recent improvements in dating and correlation. Spore assemblages provide a stratigraphic framework for plant evolutionary studies and, along with microvertebrates, enable correlation from continental to marine rocks, i.e. near-shore to shelf deposits. While it is recognized that the assemblages provide the most complete and extensive record of the history of vascular plants in a restricted geographical area during the time interval, it seems likely that major evolutionary innovation occurred elsewhere. The plants themselves display a number of types of fossilization. Particularly important are the pyrite permineralizations which have helped in the elucidation of the ultrastructure of tracheids in early vascular plants. Minute, coalified, relatively uncompressed fossils (mesofossils) from the Pȓídolí Lochkovian of the Welsh Borderland are hypothesized to be the products of wildfire, the earliest records to date. In addition to displaying often exquisite anatomical detail, the sporangia contain spores which have been linked to those in dispersed assemblages. Such relationships are helpful in the reconstruction of local and regional vegetation, even in the absence of meso-and megafossils. However, because these fossils are allochthonous and preserved in fluvial sediments, the habitats of the plants remain uncertain. A new hypothesis suggests that interfluvial areas, where calcretes are interpreted as relicts of vertisols and a seasonally dry climate, provided refugia in the Lower Devonian for the cryptosporeproducing plants which dominated Ordovician and Lower Silurian land vegetation, while vascular plants colonized areas in the immediate vicinity of rivers. Variation in regional vegetation is explored via comparisons of composition of spore assemblages in southern Britain and Scotland and timing of appearances of derived taxa, integrated with limited information on the spore producers.

show abstract

Section: Spores/ Invertebratesmentioning

confidence: 99%

Section: Spores/ Invertebratesmentioning

confidence: 99%

Silurian and Lower Devonian plant assemblages from the Anglo‐Welsh Basin: a palaeobotanical and palynological synthesis

Edwards

Richardson

2004

Geological Journal

Self Cite

View full text Add to dashboard Cite

show abstract

“…Muitos desses zoneamentos foram baseados em espécies atribuídas a acritarcos e posteriormente reinterpretadas como algas prasinofíceas (QUA-DROS 1985, OLIVEIRA 1997 Vale observar que nos depósitos cambrianos a devonianos, a bioestratigrafia do grupo está geralmente integrada a distribuição de outros elementos marinhos, tais como quitinozoários (PARIS et al 2007), graptozoários (VECOLI 1996) e invertebrados fósseis, tais como os trilobitas (RAEVSKAYA & GOLUBKOVA 2006, RAEVSKAYA & SERVAIS 2009), e com associações terrestres de miósporos (RICHARDSON et al 1981).…”

Section: Potencial Bioestratigráficounclassified

Acritarcos (grupo acritarcha evitt 1963): conceitos gerais, aplicações e importância na análise estratigráfica do intervalo pennsilvaniano e permiano da Bacia do Paraná

Félix

Souza

2012

Rev. Inst. Geol.

View full text Add to dashboard Cite

RESUMOEmbora constituam palinomorfos de natureza biológica incerta, os acritarcos são comumente utilizados para fins bioestratigráficos e de interpretação paleoambiental, principalmente para os depósitos de idade entre o Cambriano e o Devoniano. Este trabalho apresenta uma revisão atualizada sobre os aspectos morfológicos, classificação, distribuição estratigráfica e aplicações dos microfósseis de parede orgânica alocados neste grupo no âmbito das Geociências. Registros brasileiros são exemplificados, principalmente de bacias intracratônicas paleozoicas, com destaque para os depósitos pennsilvanianos e permianos da Bacia do Paraná. Como principais resultados obtidos para este intervalo na bacia, destacam-se: (i) muitos dos táxons identificados como acritarcos possivelmente têm parentesco com algas prasinofíceas e zignematáceas e (ii) a constatação de intervalos com associações abundantes em espécimes atribuídos aos gêneros Micrhystridium e Veryhachium, corroborando interpretações prévias sobre um marco estratigráfico permiano de natureza marinha, incluindo depósitos da porção superior da Formação Palermo à porção mais inferior da Formação Irati. A revisão taxonômica revela um período de declínio acentuado da diversidade de espécies (blackout fitoplanctônico) para o Carbonífero e Permiano em nível mundial, principalmente considerando a riqueza em nível genérico, muito menor que aquela observada para os depósitos pré-carboníferos no Brasil e em outras partes do mundo.Palavras-chave: palinologia, Paleozóico Superior, fitoplâncton, Bacia do Paraná, Gondwana. ABSTRACTDespite their uncertain biological affinity, the palynomorphs known as acritarchs are commonly used for biostratigraphic and paleoenvironmental interpretation, particularly of Cambrian to Devonian deposits. This paper presents an updated review of the morphology, classification and stratigraphic distribution of organicwalled microfossils included in this group, as well as their application in Geosciences. Brazilian records from Paleozoic intracratonic basins, especially from Pennsylvanian and Permian deposits of the Paraná Basin, are discussed. The main results of the analysis of this interval in the basin are (i) many of the taxa identified as acritarchs are related to species of prasinophyceae and zygnemataceae algae, and (ii) the record of intervals with abundant association of specimens assigned to the genera Micrhystridium and Veryhachium, which corroborates previous interpretations of a Permian stratigraphic marker of marine nature at the top of the Palermo Formation and base of the Irati Formation. The taxonomic review supports the idea of a worldwide decrease in diversity of these taxa during the Pennsylvanian and Permian interval (phytoplankton blackout), especially considering richness at the generic level, which was much lower than that observed in pre-Carboniferous deposits in Brazil and in other parts of the world.

show abstract

“…There are considerable difficulties involved with correlation between Upper Silurian-Lower Devonian sequences in Britain, the Ardennes-Rhenish region and the type area of Bohemia because the deposits are represented by different facies and therefore contain different groups of fossils (see Richardson, Rasul & Al-Ameri, 1981;Richardson, 1984;Richardson, Ford & Parker, 1984;Steemans, 1989). The British sequences can be correlated with those in the Ardennes-Rhenish region using spore biostratigraphy (e.g.…”

Section: C Spore Biostratigraphy and Age Determinationmentioning

confidence: 99%

“…Thus a basic intercorrelation between the four areas is achieved (e.g. Richardson, Rasul & Al-Ameri, 1981;Streel et al 1987;Steemans, 1989), although precise correlation between the type Bohemian stages (Lochkovian and Pragian) and those used in the Ardennes-Rhenish region (Gedinnian and Siegenian) has yet to be accomplished. Nevertheless, current data suggest that the breconensis-zavallatus/BZ zone, and hence the 'older' spore assemblages from the Llanstadwell Formation, are of late Lochkovian (late Gedinnian)-earliest Pragian (?earliest Siegenian) age, and the polygonalis-emsiensis/PoW zone, and hence the 'younger' spore assemblages from the Burton Cliff, Mill Bay and lowermost Lawrenny Cliff formations, are of early Pragian (?early Siegenian)-latest Pragian (?latest Siegenian) or possibly earliest Emsian age (Richardson & McGregor, 1986;Streel et al 1987;Steemans, 1989).…”

Section: C Spore Biostratigraphy and Age Determinationmentioning

confidence: 99%

The Cosheston Group (Lower Old Red Sandstone) in southwest Wales: age, correlation and palaeobotanical significance

Wellman

Thomas²,

Edwards

et al. 1998

Geol. Mag.

View full text Add to dashboard Cite

Upper Silurian–Lower Devonian ‘Lower Old Red Sandstone’ facies deposits cropping out in southwest Wales are poorly age-constrained and difficult to correlate. Spore assemblages have been recovered from sequences of these deposits belonging to the lower part of the Cosheston Group. The spore assemblages are equated with the breconensis–zavallatus and polygonalis–emsiensis Spore Assemblage Biozones and indicate an early Devonian age (late Gedinnian (late Lochkovian)–Siegenian (Pragian)). The new biostratigraphical data enable correlation of the lower part of the Cosheston Group with the Senni Beds from the main outcrop of the Lower Devonian in South Wales and the Welsh Borderland. In addition, the new age data and stratigraphical correlation place important plant megafossil assemblages from the Cosheston Group and Senni Beds in a more secure stratigraphical framework, thus facilitating comparisons with other Lower Devonian plant megafossil assemblages and enhancing palaeobotanical understanding. Evidence from palynofacies analysis supports sedimentological interpretations which suggest that the ‘Lower Old Red Sandstone’ facies deposits belonging to the Cosheston Group accumulated in a continental fluviatile environment.

show abstract

Acritarchs, miospores and correlation of the Ludlovian-Downtonian and Silurian-Devonian boundaries

Cited by 48 publications

References 8 publications

Silurian and Lower Devonian plant assemblages from the Anglo‐Welsh Basin: a palaeobotanical and palynological synthesis

Silurian and Lower Devonian plant assemblages from the Anglo‐Welsh Basin: a palaeobotanical and palynological synthesis

Acritarcos (grupo acritarcha evitt 1963): conceitos gerais, aplicações e importância na análise estratigráfica do intervalo pennsilvaniano e permiano da Bacia do Paraná

The Cosheston Group (Lower Old Red Sandstone) in southwest Wales: age, correlation and palaeobotanical significance

Contact Info

Product

Resources

About