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A revised sedimentary and biostratigraphical architecture for the Type Llandovery area, Central Wales

Published online by Cambridge University Press:  29 October 2012

JEREMY R. DAVIES*
Affiliation:
British Geological Survey, c/o Institute of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, SY23 3DB, UK
RICHARD A. WATERS
Affiliation:
Department of Geology, National Museum of Wales, Cathays Park, Cardiff, CF10 3NP, UK
STEWART G. MOLYNEUX
Affiliation:
British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK
MARK WILLIAMS
Affiliation:
Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH, UK
JAN A. ZALASIEWICZ
Affiliation:
Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH, UK
THIJS R. A. VANDENBROUCKE
Affiliation:
UMR 8217 du CNRS: Géosystèmes, Université Lille 1, bâtiment SN5, Avenue Paul Langevin, 59655 Villeneuve d'Ascq cedex, France
JACQUES VERNIERS
Affiliation:
Ghent University, WE13 Palaeontology, Krijgslaan 281 S8, BE-9000 Ghent, Belgium
*
Author for correspondence: jrdav@bgs.ac.uk

Abstract

The global standard for the Llandovery Series (early Silurian) in central Wales is re-assessed in the light of detailed geological surveying, biostratigraphical sampling and a rigorous examination of published datasets. A new sedimentary and biostratigraphical architecture is presented. Key graptolite, brachiopod, acritarch and, for the first time, chitinozoan assemblages are critically assessed. Upper Hirnantian to Aeronian strata record events that followed the Late Ordovician glacial maximum and comprise a series of progradational sequences bounded by flooding surfaces, but inferred still to be glacioeustatic in origin. Significant faunal renewals associated with many of the flooding levels underpin their potential for international recognition. Compound non-sequences are a feature of proximal parts of the system where erosion associated with fault footwall uplift was an important process. Extensive slump sheets contribute to further stratal loss and displacement in distal facies. A re-assessment of the Aeronian Stage GSSP reveals shortcomings with the biostratigraphical criteria used in its selection. Telychian portions of the succession display the disrupting effects of intra-Wenlock synsedimentary sliding; hence the relevance of key published fossil assemblages and the criteria used to erect the stage GSSP are undermined. However, the Llandovery area remains one of the best studied early Silurian successions in the world. This, together with regional considerations, supports the retention of the series standard in mid Wales where the contiguous deep-water basinal succession affords internationally cited exposure of richly graptolitic facies for the whole series and, significantly, for the post-sedgwickii Biozone interval.

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Original Articles
Copyright
Copyright © Cambridge University Press 2012

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References

Aldridge, R. J. 2000. The Llandovery Series. In British Silurian Stratigraphy (eds Aldridge, R. J., Siveter, D. J., Siveter, D. J., Lane, P. D., Palmer, D. G. & Woodcock, N. H.), pp. 69180. Geological Conservation Review Series, no. 19. Joint Nature Conservation Committee.Google Scholar
Baarli, B. G. 1986. A biometric re-evaluation of the Silurian brachiopod lineage Stricklandia lens/S. laevis . Palaeontology 29, 187205.Google Scholar
Bann, K. L. & Fielding, C. R. 2004. An integrated ichnological and sedimentological comparison of non-deltaic shoreface and subaqueous delta deposits in Permian reservoir units of Australia. In The Application of Ichnology to Palaeoenvironmental and Stratigraphic Analysis (ed. McIlroy, D.), pp. 273310. Geological Society of London, Special Publication no. 228.Google Scholar
Barclay, W. J., Davies, J. R., Humpage, A. J., Waters, R. A., Wilby, P. R., Williams, M. & Wilson, D. 2005. Geology of the Brecon District – a Brief Explanation of the Geological Map. Sheet Explanation of the British Geological Survey. 1:50 000 Sheet 213 Brecon (England and Wales). Keyworth, Nottingham: British Geological Survey, 38 pp.Google Scholar
Bassett, M. G. 1989. Brachiopods. In A Global Standard for the Silurian System (eds Holland, C. H. & Bassett, M. G.), pp. 232–42. National Museum of Wales, Geological Series no. 9.Google Scholar
Bassett, D. A. 1991. Roderick Murchison's The Silurian System: a sesquicentennial tribute. In The Murchison Symposium: Proceedings of an International Conference on the Silurian System (eds Bassett, M. G., Lane, P. D. & Edwards, D.), pp. 790. Special Papers in Palaeontology no. 44. The Palaeontological Association.Google Scholar
Bassett, M. G. & Rong, J. U. 2002. Brachiopods. In Telychian Rocks of the British Isles and China (Silurian, Llandovery Series): An Experiment to Test Precision in Stratigraphy (eds Holland, C. H. & Bassett, M. G.), pp. 124–36. National Museum of Wales, Cardiff, Geological Series no. 21.Google Scholar
Blackett, E., Page, A., Zalasiewicz, J. A., Williams, M., Rickards, R. B. & Davies, J. R. 2009. A refined graptolite biostratigraphy for the late Ordovician–early Silurian of central Wales. Lethaia 43, 8396.CrossRefGoogle Scholar
British Geological Survey. 2005 a. Builth Wells. England and Wales Sheet 196. Solid Geology, 1:50 000. Keyworth, Nottingham: British Geological Survey.Google Scholar
British Geological Survey. 2005 b. Brecon. England and Wales Sheet 213. Bedrock and Superficial Deposits, 1:50 000. Keyworth, Nottingham: British Geological Survey.Google Scholar
British Geological Survey. 2008. Llandovery. England and Wales Sheet 212. Bedrock and Superficial Deposits, 1:50 000. Keyworth, Nottingham: British Geological Survey.Google Scholar
Burgess, N. D. 1991. Silurian cryptospores and miospores from the type Llandovery area, south-west Wales. Palaeontology 34, 575–99.Google Scholar
Caputo, M. V. 1998. Ordovician–Silurian glaciations and global sea-level changes. In Silurian Cycles: Linkages of Dynamic Stratigraphy with Atmospheric, Oceanic and Tectonic Changes (eds Landing, E. & Johnson, M. E.), pp. 1525. New York State Museum Bulletin no. 491.Google Scholar
Cave, R. & Hains, B. A. 1986. Geology of the Country Between Aberystwyth and Machynlleth. Memoir of the British Geological Survey, Sheet 163 (England and Wales). Keyworth, Nottingham: British Geological Survey, 148 pp.Google Scholar
Cocks, L. R. M. 1968. Some strophomenacean brachiopods from the British Lower Silurian. Bulletin of the British Museum (Natural History), Geology Series 15, 283324.Google Scholar
Cocks, L. R. M. 1970. Silurian brachiopods of the Superfamily Plectambonitacea. Bulletin of the British Museum (Natural History), Geology Series 19, 139203.Google Scholar
Cocks, L. R. M. 1971. The Llandovery District. In Geological Excursions in South Wales and the Forest of Dean (eds Bassett, D. A. & Bassett, M. G.), pp. 155–61. The Geologists’ Association of South Wales (South Wales Group).Google Scholar
Cocks, L. R. M. 1978. A review of British Lower Palaeozoic brachiopods, including a synoptic revision of Davidson's monograph. Monograph of the Palaeontographical Society, London 131, 1256.Google Scholar
Cocks, L. R. M. 1989. The Llandovery Series in the Llandovery area. In A Global Standard for the Silurian System (eds Holland, C. H. & Bassett, M. G.), pp. 3650. National Museum of Wales, Cardiff, Geological Series no. 9.Google Scholar
Cocks, L. R. M., Forty, R. A. & Rushton, A. W. A. 2010. Correlation for the Lower Palaeozoic. Geological Magazine 147, 171–80.CrossRefGoogle Scholar
Cocks, L. R. M., Holland, C. H., Rickards, R. B. & Strachan, I. 1971. A correlation of Silurian rocks in the British Isles. Journal of the Geological Society, London 127, 103–36.CrossRefGoogle Scholar
Cocks, L. R. M., Toghill, P. & Ziegler, A. M. 1970. Stage names within the Llandovery Series. Geological Magazine 107, 7987.CrossRefGoogle Scholar
Cocks, L. R. M., Woodcock, N. H., Rickards, R. B., Temple, J. T. & Lane, P. D. 1984. The Llandovery Series of the type area. Bulletin of the British Museum (Natural History), Geology Series 38, 131–82.Google Scholar
Cramer, F. H. 1968. Palynologic microfossils of the Middle Silurian Maplewood Shale in New York. Revue de Micropaléontologie 11 (2), 6170, pl. 1.Google Scholar
Cramer, F. H. 1970. Distribution of selected Silurian acritarchs; an account of the palynostratigraphy and paleogeography of selected Silurian acritarch taxa. Revista Española de Micropaleontología (número extraordinario), 1–203, pls I–XXIII.Google Scholar
Cramer, F. H. & Díez de Cramer, M. del C. R. 1972. North American Silurian palynofacies and their spatial arrangement: acritarchs. Palaeontographica Abteilung B 138, 107–80, pls 31–6.Google Scholar
Cramer, B. D., Loydell, D. K., Samtleben, C., Munnecke, A., Kaljo, D., Männik, P., Martma, T., Jeppsson, L., Kleffner, M. A., Barrick, J. E., Johnson, C. A., Emsbo, P., Joachimski, M. M., Bickert, T. &. Saltzman, M. R. 2010. Testing the limits of Paleozoic chronostratigraphic correlation via high-resolution (<500kyr) integrated conodont, graptolite, and carbon isotope (δ13Ccarb) biochemostratigraphy across the Llandovery-Wenlock (Silurian) boundary: is a unified Phanerozoic timescale achievable? Geological Society of America Bulletin 122, 1700–16.CrossRefGoogle Scholar
Cullum, A. A. & Loydell, D. K. 2011. The Rhuddanian/Aeronian transition in the Rheidol Gorge, mid Wales. Proceedings of the Yorkshire Geological Society 58, 261–66.CrossRefGoogle Scholar
Davies, J. R., Fletcher, C. J. N., Waters, R. A., Wilson, D., Woodhall, D. G. & Zalasiewicz, J. A. 1997. Geology of the Country Around Llanilar and Rhayader. Memoir of the British Geological Survey, Sheets 178 and 179 (England and Wales). Keyworth, Nottingham: British Geological Survey, 267 pp.Google Scholar
Davies, J. R., Molyneux, S. G., Vandenbroucke, T. R. A., Verniers, J., Waters, R. A., Williams, M. & Zalasiewicz, J. A. 2011. Pre-conference field trip to the Type Llandovery area. In Siluria Revisited: A Field Guide (ed. Ray, D. C.), pp. 2972. International Subcommission on Silurian Stratigraphy, Field Meeting, 2011.Google Scholar
Davies, J. R. & Waters, R. A. 1995. The Caban Conglomerate and Ystrad Meurig Grits Formation – nested channels and lobe switching on a mud-dominated latest Ashgill to Llandovery slope apron, Welsh Basin, UK. In Atlas of Deep Water Environments: Architectural Style in Turbidite Systems (eds Pickering, K. T, Hiscott, R. N., Kenyon, N. H., Ricci Lucci, F. & Smith, R. D. A.), pp. 184–93. London: Chapman & Hall.CrossRefGoogle Scholar
Davies, J. R., Waters, R. A. & Copus, J. 1999. Facies and geometry of deep-water turbidite systems in the Lower Palaeozoic Welsh Basin. AAPG International Conference (Birmingham), Field Trip 2: 8–11 September. British Geological Survey Technical Report (WA/00/095).Google Scholar
Davies, J. R., Waters, R. A., Williams, M., Wilson, D., Schofield, D. I. & Zalasiewicz, J. A. 2009. Sedimentary and faunal events revealed by a revised correlation of post-glacial Hirnantian (late Ordovician) strata in the Welsh basin, U.K. Geological Journal 44, 322–40.CrossRefGoogle Scholar
Davies, J. R., Waters, R. A., Zalasiewicz, J. A., Molyneux, S. G., Vandenbroucke, T. R. A. & Williams, M. 2010. A revised sedimentary and biostratigraphical architecture for the type Llandovery and Garth areas, central Wales: a field guide. British Geological Survey Open Report, OR/10/037.Google Scholar
De Permentier, J. & Verniers, J. 2002. Chitinozoans from the global stratigraphical sections and points (GSSP) of the bases of the Aeronian and the Telychian (Llandovery) in Wales, U.K. In Palaeozoic Palynology in the Third Millenium: New Directions in Acritarch, Chitinozoan and Miospore Research, p. 16. Abstracts volume, International Meeting and Workshop of the International Commission of the Palaeozoic Microflora, Lille, France, 5–7 September 2002.Google Scholar
Deunff, J. & Evitt, W. R. 1968. Tunisphaeridium, a new acritarch genus from the Silurian and Devonian. Stanford University Publications, Geological Sciences 12 (1), 113, pl. 1.Google Scholar
Dias-Martinez, E. & Grahn, Y. 2007. Early Silurian glaciation along the western margin of Gondwana (Peru, Bolivia and northern Argentina): palaeogeography and geodynamic setting. Palaeogeography, Palaeoclimatology, Palaeoecology 252, 6281.CrossRefGoogle Scholar
Dorning, K. J. & Bell, D. G. 1987. The Silurian carbonate shelf microflora: acritarch distribution in the Much Wenlock Limestone Formation. In Micropalaeontology of Carbonate Environments (ed. Hart, M. B.), pp. 266–87. Chichester: Ellis Horwood.Google Scholar
Doyle, E. N., Hoey, A. N. & Harper, D. A. T. 1994. The rhynchonellide brachiopod Eocoelia from the upper Llandovery of Ireland and Scotland. Palaeontology 34, 439–54.Google Scholar
Duval, B., Cramez, C. & Vail, P. R. 1992. Types and hierarchy of stratigraphic cycles. In Sequence Stratigraphy of European Basins, pp. 44–5. Abstracts volume, Centre National de la Recherche Scientifique & Institut Francais du Pétrole, Dijon, 1992.Google Scholar
Eisenack, A., Cramer, F. H. & Díez, M. del C. R. 1973. Katalog der Fossilen Dinoflagellaten, Hystrichosphären und Verwandten Mikrofossilien. Band III Acritarcha 1. Teil. Stuttgart: E. Schweizerbart'sche Verlagsbuchhandlung, 1104 pp.Google Scholar
Eisenack, A., Cramer, F. H. & Díez, M. del C. R. 1976. Katalog der Fossilen Dinoflagellaten, Hystrichosphären und Verwandten Mikrofossilien. Band IV Acritarcha 2. Teil. Stuttgart: E. Schweizertbart'sche Verlagsbuchhandlung, 863 pp.Google Scholar
Floyd, J. D. & Williams, M. 2003. A revised lithostratigraphy for the Silurian of the Girvan district. Transactions of the Royal Society of Edinburgh: Earth Sciences 93, 383–92.CrossRefGoogle Scholar
Gawthorpe, R. L., Hall, M., Sharp, I. & Dreyer, T. 2000. Tectonically enhanced forced regressions: examples from growth folds in extensional and compressional settings, the Miocene of the Suez and the Eocene of the Pyrenees. In Sedimentary Responses to Forced Regressions (eds Hunt, D. & Gawthorpe, R. L.), pp. 177–91 Geological Society of London, Special Publication no. 172.Google Scholar
Haq, B. U. & Schutter, S. R. 2008. A chronology of Paleozoic sea-level change. Science 322, 64–8.CrossRefGoogle Scholar
Hill, P. J. & Dorning, K. J. 1984. Appendix 1: Acritarchs. In The Llandovery Series of the Type Area (Cocks, L. R. M., Woodcock, N. H., Rickards, R. B., Temple, J. T. & Lane, P. D.), pp. 174–76. Bulletin of the British Museum (Natural History), Geology Series 38, 131–82.Google Scholar
Holland, C. H. 1989. Principles, history and classification. In A Global Standard for the Silurian System (eds Holland, C. H. & Bassett, M. G.), pp. 726. National Museum of Wales, Cardiff, Geological Series no. 9.Google Scholar
Holland, C. H. & Bassett, M. G. 1988. Discussion on biostratigraphical correlation and the stages of the Llandovery. Journal of the Geological Society, London 145, 881–2.Google Scholar
Holland, C. H. & Bassett, M. G. 2002. Telychian Rocks of the British Isles and China (Silurian, Llandovery Series): An Experiment to Test Precision in Stratigraphy. National Museum of Wales, Cardiff, Geological Series, no. 21.Google Scholar
Hurst, J. M., Hancock, N. J. & McKerrow, W. S. 1978. Wenlock stratigraphy and palaeogeography of Wales and the Welsh borderland. Proceedings of the Geologists’ Association 89, 197226.CrossRefGoogle Scholar
Jin, J. & Copper, P. 1999. The deep-water brachiopod Dicoelosia King, 1850, from the early Silurian tropical carbonate shelf of Anticosti Island, Eastern Canada. Journal of Paleontology 73, 1042–55.CrossRefGoogle Scholar
Johnson, M. E. 2006. Relationship of Silurian sea-level fluctuations to oceanic episodes and events. GFF 128, 115–21.CrossRefGoogle Scholar
Johnson, M. E. 2010. Tracking Silurian eustasy: alignment of empirical evidence or pursuit of deductive reasoning? Palaeogeography, Palaeoclimatology, Palaeoecology 296, 276–84.CrossRefGoogle Scholar
Johnson, M. E., Kaljo, D. K. & Rong, J.-Y. 1991. Silurian eustasy. In The Murchison Symposium: Proceedings of an International Conference on the Silurian System (eds Bassett, M. G., Lane, P. D. & Edwards, D.), pp. 145–63. Special Papers in Palaeontology no. 44. The Palaeontological Association.Google Scholar
Johnson, M. E., Rong, J. U. & Yang, X. C. 1985. Intercontinental correlation by sea-level events in the early Silurian of North America and China (Yangtze platform). Geological Society of America Bulletin 96, 1384–97.2.0.CO;2>CrossRefGoogle Scholar
Jones, O. T. 1909. The Hartfell‑Valentian succession in the district around Plynlimon and Pont Erwyd (north Cardiganshire). Quarterly Journal of the Geological Society of London 65, 463537.CrossRefGoogle Scholar
Jones, O. T. 1921. The Valentian Series. Quarterly Journal of the Geological Society of London 77, 144–74.CrossRefGoogle Scholar
Jones, O. T. 1925. The geology of the Llandovery district. Part I: the southern area. Quarterly Journal of the Geological Society of London 81, 344–88.CrossRefGoogle Scholar
Jones, O. T. 1928. Plectambonites and some allied genera. Memoir of the Geological Survey, UK, London, (Palaeontology) 1, 367527.Google Scholar
Jones, O. T. 1949. The geology of the Llandovery district. Part II: the northern area. Quarterly Journal of the Geological Society of London 105, 4364.CrossRefGoogle Scholar
Jones, O. T. & Williams, A. 1949. Appendix – Note on the Llandovery rocks on the River Sefin, near Llangadock. Quarterly Journal of the Geological Society of London 105, 61–3.Google Scholar
Lapworth, H. 1900. The Silurian sequence of Rhayader. Quarterly Journal of the Geological Society of London 56, 67137.CrossRefGoogle Scholar
Lister, T. R. 1970. The Acritarchs and Chitinozoa from the Wenlock and Ludlow Series of the Ludlow and Millichope areas, Shropshire. Monograph of the Palaeontographical Society, London 124, 1100, pls 1–13.Google Scholar
Loydell, D. K. 1991. The biostratigraphy and formational relationships of the upper Aeronian and lower Telychian (Llandovery, Silurian) formations of western mid‑Wales. Geological Journal 26, 209–44.CrossRefGoogle Scholar
Loydell, D. K. 1992. Upper Aeronian and Lower Telychian (Llandovery) graptolites from western mid-Wales. Part 1. Monograph of the Palaeontographical Society, London 146, 155.Google Scholar
Loydell, D. K. 1998. Early Silurian sea-level changes. Geological Magazine 135, 447–71.CrossRefGoogle Scholar
Loydell, D. K. 2007. Early Silurian positive δ13C excursions and their relationship to glaciations, sea level changes and extinction events. Geological Journal 42, 531–46.CrossRefGoogle Scholar
Loydell, D. K. 2012. Graptolite biozone correlation charts. Geological Magazine 149, 124–32.CrossRefGoogle Scholar
Loydell, D. K. & Cave, R. 1996. The Llandovery–Wenlock boundary and related stratigraphy in eastern mid Wales with special reference to the Banwy River section. Newsletters on Stratigraphy 34, 3964.CrossRefGoogle Scholar
Martin, M. A. & Pollard, J. E. 1996. The role of trace fossil (ichnofabric) analysis in the development of depositional models for the Upper Jurassic Fulmar Formation of the Kittiwake Field (Quadrant 21 UKCS). In Geology of the Humber Group: Central Graben and Moray Firth UKCS (eds Hurst, A., Johnson, H., Burley, S. D., Canham, A. C. & Mackertich, D. S.), pp. 163–83. Geological Society of London, Special Publication no. 114.Google Scholar
Melchin, M. J., Cooper, R. A. & Sadler, P. M. 2004. The Silurian Period. In A Geological Time Scale 2004 (eds Gradstein, F. M., Ogg, J. G. & Smith, A. G.), pp. 188201. Cambridge: Cambridge University Press.Google Scholar
Molyneux, S. G. 2003. Palynological report on samples from Crychan Forest. British Geological Survey Internal Report, IR/03/054R.Google Scholar
Mullins, G. L. & Loydell, D. K. 2002. Integrated lower Silurian chitinozoan and graptolite biostratigraphy of Buttington Brick Pit, Wales. Geological Magazine 139, 8996.CrossRefGoogle Scholar
Munnecke, A., Calner, M., Harper, D. A. T. & Servais, T. 2010. Ordovician and Silurian sea-water chemistry, sea level and climate: a synopsis. Palaeogeography, Palaeoclimatology, Palaeoecology 296, 389413.CrossRefGoogle Scholar
Murchison, R. I. 1867. Siluria, 4th ed. John Murray.Google Scholar
Page, A. A., Zalasiewicz, J. A., Williams, M. & Popov, L. E. 2007. Were transgressive black shales a negative feedback modulating glacioeustasy during the Early Palaeozoic Icehouse? In Deep Time Perspectives on Climate Change: Marrying the Signal From Computer Models and Biological Proxies (eds Williams, M., Haywood, A. M., Gregory, F. J. & Schmidt, D. N.), pp. 123–56. The Micropalaeontological Society Special Publications. London: The Geological Society.Google Scholar
Postma, G. 1990. Depositional architecture and facies of river and fan deltas: a synthesis. In Coarse Grained Deltas (eds Colella, A. & Prior, D. B.), pp. 1327. Special Publication of the International Association of Sedimentologists, no. 10.CrossRefGoogle Scholar
Reineck, H.-E. & Singh, I. B. 1975. Depositional Sedimentary Environments – With Reference to Terrigenous Clastics. Berlin: Springer-Verlag, 439 pp.Google Scholar
Ross, C. A. & Ross, R. P. 1996. Silurian sea level fluctuations. In Paleozoic Sequence Stratigraphy: Views from the North American Craton (eds Witzke, B. J., Ludvigson, G. A. & Day, J.), pp. 187–92. Geological Society of America, Special Paper no. 306.CrossRefGoogle Scholar
Schofield, D. I., Davies, J. R., Jones, N. S., Leslie, A. B., Waters, R. A., Williams, M., Wilson, D., Venus, J. & Hillier, R. D. 2009 b. Geology of the Llandovery District – A Brief Explanation of the Geological Map. Sheet Explanation of the British Geological Survey. 1:50 000 Sheet 212 Llandovery (England and Wales). Keyworth, Nottingham: British Geological Survey.Google Scholar
Schofield, D. I., Davies, J. R., Waters, R. A., Wilby, P. R., Williams, M. & Wilson, D. 2004. Geology of the Builth Wells District – A Brief Explanation of the Geological Map. Sheet Explanation of the British Geological Survey. 1:50 000 Sheet 196 Builth Wells (England and Wales). Keyworth, Nottingham: British Geological Survey.Google Scholar
Schofield, D. I., Davies, J. R., Waters, R. A., Williams, M & Wilson, D. 2009 a. A new Early Silurian turbidite system in Central Wales: insights into eustatic and tectonic controls on deposition in the southern Welsh basin. Geological Magazine 146, 121–32.CrossRefGoogle Scholar
Siveter, D. J., Owens, R. M. & Thomas, A. T. 1989. Silurian field excursions: a geotraverse across Wales and the Welsh Borderland. National Museum of Wales, Cardiff, Geological Series no. 10.Google Scholar
Smelror, M. 1987. Early Silurian acritarchs and prasinophycean algae from the Ringerike District, Oslo Region (Norway). Review of Palaeobotany and Palynology 52, 137–59.CrossRefGoogle Scholar
Sudbury, M. 1958. Triangulate monograptids from the Monograptus gregarious Zone (lower Llandovery) of the Rheidol gorge (Cardiganshire). Philosophical Transactions of the Royal Society of London B241, 485555.CrossRefGoogle Scholar
Taylor, A. M. & Goldring, R. 1993. Description and analysis of bioturbation and ichnofabric. Journal of the Geological Society, London 159, 141–48.CrossRefGoogle Scholar
Temple, J. T. 1987. Early Llandovery brachiopods of Wales. Monograph of the Palaeontographical Society, London 139, 1137.Google Scholar
Temple, J. T. 1988. Biostratigraphical correlation and stages of the Llandovery. Journal of the Geological Society, London 145, 875–9.CrossRefGoogle Scholar
Vandenbroucke, T. R. A. 2008. An Upper Ordovician chitinozoan biozonation in British Avalonia (England & Wales). Lethaia 41, 275–94.CrossRefGoogle Scholar
Vandenbroucke, T. R. A., Hennissen, J., Zalasiewicz, J. A. & Verniers, J. 2008. New chitinozoans from the historical type area of the Hirnantian and additional key sections in the Wye valley, Wales, UK. Geological Journal 43, 397414.CrossRefGoogle Scholar
Van Wagoner, J. C., Mitchum, R. M., Campion, K. M., & Rahmanian, V. D. 1990. Siliclastic Sequence Stratigraphy in Well Logs, Cores and Outcrops: Concepts for High-resolution Correlation of Time and Facies. Association of American Petroleum Geologists Methods in Exploration Series no. 7.Google Scholar
Verniers, J. 1999. Calibration of Chitinozoa versus graptolite biozonation in the Wenlock of Builth Wells district (Wales, UK), compared with other areas in Avalonia and Baltica. Bollettino della Societa Paleontologica Italiana 38, 122.Google Scholar
Verniers, J., Nestor, V., Paris, F., Dufka, P., Sutherland, S. & Van Grootel, G. 1995. A global Chitinozoa biozonation for the Silurian. Geological Magazine 132, 651–66.CrossRefGoogle Scholar
Weise, B. R. 1980. Wave-Dominated Delta Systems of the Upper Cretaceous San Miguel Formation, Maverick Basin, South Texas. Report of Investigations, 107. Austin, Texas: Bureau of Economic Geology.Google Scholar
Wescott, W. A. & Etherridge, F. G. 1990. Fan deltas – alluvial fans in coastal settings. In Alluvial Fans: A Field Approach (eds Rachocki, A. H. & Church, M.), pp. 195211. Chichester: John Wiley & Sons.Google Scholar
Williams, A. 1951. Llandovery brachiopods from Wales with special reference to the Llandovery district. Quarterly Journal of the Geological Society of London 107, 85136.CrossRefGoogle Scholar
Williams, A. 1953. The geology of the Llandeilo district, Carmarthenshire. Quarterly Journal of the Geological Society of London 108, 177205.CrossRefGoogle Scholar
Williams, S. H. & Ingham, J. K. 1989. The Ordovician-Silurian boundary stratotype at Dob's Lin, southern Scotland. In A Global Standard for the Silurian System (eds Holland, C. H., & Bassett, M. G.), pp. 2735. National Museum of Wales, Cardiff, Geological Series no. 9.Google Scholar
Wood, E. M. R. 1906. On the Tarannon Series of Tarannon. Quarterly Journal of the Geological Society of London 62, 644701.CrossRefGoogle Scholar
Wood, G. D. 1996. Biostratigraphic, paleoecologic and biologic significance of the Silurian (Llandovery) acritarch Beromia rexroadii gen. emend. et sp. nov., Mid-continent and Eastern United States. Palynology 20, 177–89.CrossRefGoogle Scholar
Woodcock, N. H. 1987. Structural geology of the Llandovery Series in the type area, Dyfed, Wales. Geological Journal 22, 199209.CrossRefGoogle Scholar
Woodcock, N. H., Butler, A. J., Davies, J. R. & Waters, R. A. 1996. Sequence stratigraphical analysis of late Ordovician and early Silurian depositional systems in the Welsh basin: a critical assessment. In Sequence Stratigraphy in British Geology (eds Hesselbo, S. P. & Parkinson, D. N.), pp. 197208. Geological Society of London, Special Publication no. 103.Google Scholar
Woodcock, N. H. & Gibbons, W. 1988. Is the Welsh Borderland Fault System a terrane boundary? Journal of the Geological Society, London 145, 915–23.CrossRefGoogle Scholar
Woodcock, N. H. & Smallwood, S. D. 1987. Late Ordovician shallow marine environments due to glacio-eustatic regression: Scrach Formation, mid-Wales. Journal of the Geological Society, London 144, 393400.CrossRefGoogle Scholar
Woodcock, N. H., Soper, N. J. & Strachan, R. A. 2007. A Rheic cause for the Acadian deformation in Europe. Journal of the Geological Society, London 164, 1023–36.CrossRefGoogle Scholar
Zalasiewicz, J. A. 1990. Silurian graptolite biostratigraphy in the Welsh Basin. Journal of the Geological Society, London 147, 619–22.CrossRefGoogle Scholar
Zalasiewicz, J. A. 1994. Middle to late Telychian (Silurian:Llandovery) graptolite assemblages of central Wales. Palaeontology 37, 375–96.Google Scholar
Zalasiewicz, J. A. 1996. Aeronian (Silurian:Llandovery) graptolite assemblages from central Wales. Geologica et Palaeontologica 30, 301–14.Google Scholar
Zalasiewicz, J. A., Taylor, L., Rushton, A. W. A., Loydell, D. K., Rickards, R. B. & Williams, M. 2009. Graptolites in British stratigraphy. Geological Magazine 146, 785850.CrossRefGoogle Scholar
Zalasiewicz, J. A. & Tunnicliff, S. 1994. Uppermost Ordovician to Lower Silurian graptolite biostratigraphy of the Wye valley, central Wales. Palaeontology 37, 695720.Google Scholar
Zalasiewicz, J. A. & Williams, M. 1999. Graptolite biozonation of the Wenlock Series (Silurian) of the Builth Wells district, central Wales. Geological Magazine 136, 263–83.CrossRefGoogle Scholar
Zhang, S. & Barnes, C. R. 2002. Late Ordovician-Early Silurian (Ashgillian-Llandovery) sea level curve derived from conodont community analysis, Anticosti Island, Quebec. Palaeogeography, Palaeoclimatology, Palaeoecology 180, 532.CrossRefGoogle Scholar
Zhang, S., Barnes, C. R. & Jowett, D. M. S. 2006. The paradox of the global standard Late Ordovician–Early Silurian sea level curve: evidence form conodont community analysis from both Canadian Arctic and Appalachian margins. Palaeogeography, Palaeoclimatology, Palaeoecology 236, 246–71.CrossRefGoogle Scholar
Ziegler, A. M. 1965. Silurian marine communities and their environmental significance. Nature, London 207, 270–2.CrossRefGoogle Scholar
Ziegler, A. M. 1966. The Silurian brachiopod Eocoelia hemisphaerica (J. de C. Sowerby) and related species. Palaeontology 9, 523–43.Google Scholar
Ziegler, A. M., Cocks, L. R. M. & Bambach, R. K. 1968. The composition and structure of Silurian marine communities. Lethaia 1, 127.CrossRefGoogle Scholar
Ziegler, A. M., Cocks, L. R. M. & McKerrow, W. S. 1968. The Llandovery transgression of the Welsh Borderland. Palaeontology 11, 736–82.Google Scholar
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A revised sedimentary and biostratigraphical architecture for the Type Llandovery area, Central Wales
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A revised sedimentary and biostratigraphical architecture for the Type Llandovery area, Central Wales
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