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Acritarch dating of latest Tremadoc – earliest Arenig (early Ordovician) sediments in the Carmarthen district, south Wales

Published online by Cambridge University Press:  01 May 2009

S. G. Molyneux  and
K. J. Dorning
S. G. Molyneux
Affiliation:
British Geological Survey, Keyworth, Nottingham NG12 5GG, U.K.
K. J. Dorning
Affiliation:
Pallab Research, 58 Robertson Road, Sheffield S6 5DX, U.K.
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Abstract

An acritarch assemblage from beds beneath the Ogof Hên Formation near Carmarthen (the ‘Login beds’) resembles assemblages from the Watch Hill Grits and underlying sediments of latest Tremadoc or earliest Arenig age in the Skiddaw Group of the English Lake District. We conclude that the Login acritarch assemblage is younger than at least some part of the late Tremadoc Angelina sedgwickii Biozone, but older than the early Arenig Didymograptus deflexus Biozone. Its occurrence may therefore coincide with that of the graptolite Tetragraptus approximatus. This is of particular significance in any attempt to define an internationally correlatable base for the Arenig Series in Britain.

Type
Articles
Information
Geological Magazine , Volume 126 , Issue 6 , November 1989 , pp. 707 - 714
Copyright
Copyright © Cambridge University Press 1989

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References

Burmann, G. 1970. Weitere organische Mikrofossilien aus dem unteren Ordovizium. Paläontologische Abhandlungen, Abteilung B, 3 (3–4), 289–332.Google Scholar
Cocchio, A. M. 1982. Données nouvelles sur les Acritarches du Trémadoc et de l'Arenig dans le Massif de Mouthoumet (Corbières, France). Revue de Micropaléontologie 25, 26–39.Google Scholar
Combaz, A. 1968. Un microbios du Trémadocien dans un sondage d'Hassi-Messaoud. Actes de la Société linnéenne de Bordeaux 104, série B, no. 29, 26 pp., 4 pls, (dated 1967).Google Scholar
Cooper, R. A. 1979. Sequence and correlation of Tremadoc graptolite assemblages. Alcheringa 3, 7–19.CrossRefGoogle Scholar
Cope, J. C. W., Fortey, R. A. & Owens, R. M. 1978. Newly discovered Tremadoc rocks in the Carmarthen district, South Wales. Geological Magazine 115, 195–8.CrossRefGoogle Scholar
Cramer, F. H. & Diez, M., del, C. R. 1977. Late Arenigian (Ordovician) acritarchs from Cis-Saharan Morocco. Micropaleontology 23, 339–60.CrossRefGoogle Scholar
Dean, W. T. & Martin, F. 1978. Lower Ordovician acritarchs and trilobites from Bell Island, Eastern Newfoundland. Geological Survey of Canada Bulletin no. 284, 35pp.CrossRefGoogle Scholar
Deflandre, G. & Deflandre-Rigaud, M. 1962. Nomenclature et systématique des Hystrichospheres (sens. lat.). Observations et rectifications. Revue de Micropaléontologie 4, 190–6.Google Scholar
Deunff, J. 1959. Microorganismes planctonique du Primaire armoricain. I. Ordovicien du Veryhac'h (Presqu'ile de Crozon). Bulletin de la Société géologique et minéralogique de Bretagne (nouvelle sérié), for 1958, (2), 1–41.Google Scholar
Deunff, J. 1961. Un microplancton à Hystrichosphères dans le Trémadoc du Sahara. Revue de Micropaléontologie 4, 37–52.Google Scholar
Deunff, J., Górka, H. & Rauscher, R. 1974. Observations nouvelles et précisions sur les Acritarches à large ouverture polaire du Paléozoique inférieur. Geobios 7, 5–18, pls 1–7.CrossRefGoogle Scholar
Downie, C. 1958. An assemblage of microplankton from the Shineton Shales (Tremadocian). Proceedings of the Yorkshire Geological Society 31, 331–49, pls 16, 17.Google Scholar
Fortey, R. A. & Owens, R. M. 1978. Early Ordovician (Arenig) stratigraphy and faunas of the Carmarthen district, south-west Wales. Bulletin of the British Museum of Natural History (Geology) 30, 225–94, 11 pls.Google Scholar
Fortey, R. A. & Owens, R. M. 1987. The Arenig Series in South Wales: Stratigraphy and Palaeontology. I. The Arenig Series in South Wales. Bulletin of the British Museum of Natural History (Geology) 41, 69–307.Google Scholar
Górka, H. 1967. Quelques nouveaux Acritarches des silexites du Trémadocien supérieur de la région de Kielce (Montagne de Ste Croix, Pologne). Cahiers de Micropaléontologie, série 1, no. 6, 8 pp., 2 pls.Google Scholar
Jardiné, S., Combaz, A., Magloire, L., Peniguel, G. & Vachey, G. 1974. Distribution stratigraphique des Acritarches dans le Paléozoique du Sahara Algérien. Review of Palaeobotany and Palynology 18, 99–129.CrossRefGoogle Scholar
Martin, F. 1969. Les Acritarches de l'Ordovicien et du Silurien belges. Détermination et valeur stratigraphique. Mémoires de l'Institut royal des sciences naturelles de Belgique no. 160, 175 pp., 8 pls (dated 1968).Google Scholar
Martin, F. & Dean, W. T. 1981. Middle and Upper Cambrian and Lower Ordovician acritarchs from Random Island, Eastern Newfoundland. Geological Survey of Canada Bulletin no. 343, 43 pp.Google Scholar
Molyneux, S. G. 1987. The Arenig Series in South Wales: Stratigraphy and Palaeontology. II. Appendix. Acritarchs and Chitinozoa from the Arenig Series of South-west Wales. Bulletin of the British Museum of Natural History (Geology) 41, 309–64.Google Scholar
Molyneux, S. G. & Rushton, A. W. A. 1988. The age of the Watch Hill Grits (Ordovician), English Lake District: structural and palaeogeographical implications. Transactions of the Royal Society of Edinburgh: Earth Sciences 79, 43–69.CrossRefGoogle Scholar
Monsen, A. 1937. Die graptolithenfauna im Unteren Didymograptusschiefer (Phyllograptusschiefer) Norwegens. Norsk Geologisk Tidsskrift 16, 57–266, pls 1–20.Google Scholar
Owens, R. M. & Fortey, R. A. 1982. Arenig rocks of the Carmarthen–Llanarthney District. In Geological Excursions in Dyfed, South-West Wales (ed. Bassett, M. G.), pp. 249–58. National Museum of Wales, Cardiff.Google Scholar
Owens, R. M., Fortey, R. A., Cope, J. C. W., Rushton, A. W. A. & Bassett, M. G. 1982. Tremadoc faunas from the Carmarthen district, South Wales. Geological Magazine 119, 1–38.CrossRefGoogle Scholar
Rasul, S. M. 1974. The Lower Palaeozoic acritarchs Priscogalea and Cymatiogalea. Palaeontology 17, 41–63.Google Scholar
Rasul, S. M. 1976. New species of the genus Vulcanisphaera (Acritarcha) from the Tremadocian of England. Micropaleontology 22, 479–84.CrossRefGoogle Scholar
Rasul, S. M. 1979. Acritarch zonation of the Tremadoc Series of the Shineton Shales, Wrekin, Shropshire, England. Palynology 3, 53–72.CrossRefGoogle Scholar
Rasul, S. M. & Downie, C. 1974. The stratigraphic distribution of Tremadoc acritarchs in the Shineton Shales succession, Shropshire, England. Review of Palaeobotany and Palynology 18, 1–9.CrossRefGoogle Scholar
Stone, P. & Rushton, A. W. A. 1983. Graptolife faunas from the Ballantrae ophiolite complex and their structural implications. Scottish Journal of Geology 19, 297–310.CrossRefGoogle Scholar
Thomas, D. E. 1960. The zonal distribution of Australian graptolites. Journal and Proceedings, Royal Society of New South Wales 94, 1–58, pls 1–15.Google Scholar
Tjernvik, T. E. & Johansson, J. V. 1980. Description of the upper portion of the drill-core from Finngrundet in the South Bothnian Bay. Bulletin of the Geological Institution of the University of Uppsala, new series 8, 173–204.Google Scholar
Vanguestaine, M. 1978. Critères palynostratigraphiques conduisant à la reconnaissance d'un pli couché Revinien dans le sondage de Grand-Halleux. Annales de la Société géologique de Belgique 100, 249–76.Google Scholar
Vavrdová, M. 1972. Acritarchs from Klabava Shales (Arenig). Věstnik Ústředniho ústavu geologického 47, 79–86.Google Scholar
Vavrdová, M. 1976. Excystment mechanism of Early Paleozoic acritarchs. Časopis pro mineralogii a geologii 21, 55–63, 4 pls.Google Scholar