Location of Repository

Characterisation of stratigraphy and palaeoceanography using graptolites: exploring new concepts in the Aeronian (Silurian) of Wales, Scotland and Northern Ireland

By Andrea Marie Snelling

Abstract

Graptolites, extinct macrozooplankton of the phylum Hemichordata were a major element of the Early Palaeozoic seas. They are here investigated from Wales, Scotland and Northern Ireland and their use beyond biostratigraphy is considered.\ud The leptotheca and convolutus biozones (Aeronian; Silurian) are characterized and\ud correlated across Wales, Scotland and Northern Ireland, and in Scotland subdivision\ud of the convolutus Biozone was possible through identification of Cephalograptus\ud cometa extrema. In the Irish successions, previously unrecognized morphological\ud intermediates within the established Petalolithus-Cephalograptus lineage were\ud recognised and in Wales and Scotland, ‘pre-maxiculus’ morphotypes of\ud Coronograptus are suggested. At all three localities Campograptus lobiferus is the\ud dominant species with intraspecific variation recorded; the type material of this\ud species from Scotland is shown to be unusually large. Use of X-ray images has\ud enhanced biostratigraphy by enabling more specimens and taxa to be recorded,\ud shown how graptolite number varies microstratigraphically and demonstrated that\ud rhabdosomes are systematically aligned. The number and thickness of Aeronian\ud ‘anoxic’ units varies within Wales, and between the Welsh and Scottish\ud successions, indicating diachroneity of anoxia. A schema of microfacies types is\ud constructed for the leptotheca Biozone anoxic unit in Wales and is applied to the\ud Welsh convolutus Biozone anoxic units and to the gregarius to convolutus Biozone\ud strata in Scotland. Facies with less clastic input and no burrows are associated with\ud the best preserved graptolites, with pyrite formation being influenced by variations\ud in palaeoproductivity and clastic input. Levels with well-preserved graptolites are\ud not geochemically distinct, but differences in the major elements indicate\ud provenance differences between the leptotheca and convolutus biozones. A\ud reproducible &delta ^{13}C signal is obtainable from small amounts of carbon from graptolite periderm and periderm &delta^{13}C is different but not consistently so to whole-rock &delta^{13}C.\ud Initial results suggest that periderm &delta^{13}C is not affected by physiology, life habit or metamorphic grade and that for chemostratigraphic study little regard is needed for species composition

Publisher: University of Leicester
Year: 2009
OAI identifier: oai:lra.le.ac.uk:2381/7532

Suggested articles

Preview

Citations

  1. (1997). A bibliographic index of British graptolites (Graptoloidea).
  2. (1976). A Caledonian plate tectonic model.
  3. (1901). A monograph of British Graptolites. Editited by C. Lapworth London, Monograph of the Palaeontographical Society.
  4. A monograph of the British Graptolitidae.
  5. (2009). A new Early Silurian turbidite system in Central Wales: insights into eustatic and tectonic controls on deposition in the southern Welsh Basin.
  6. (1980). A physical model for the transport and sorting of fine-grained sediment by turbidity currents.
  7. (1969). A redescription of W. Carruthers' type graptolites.
  8. (2009). A refined graptolite biostratigraphy for the late Ordovician-early Silurian of central Wales.
  9. (2004). A revised graptolite biostratigraphy for the lower Caradoc(Upper Ordovician) of southern Scotland.
  10. (1985). A small coleoid cephalopod with soft parts from the lower Devonian discovered using radiography.
  11. (1971). A synoptic supplement to “A monograph of British graptolites by
  12. (1996). Aeonian (Silurian:Llandovery) graptolites from central Wales..
  13. (1990). An oceanic model for lithological and faunal changes tested on the Silurian record.
  14. (1990). Anoxia vs. productivity: what controls the formation of organic-carbon rich sediments and sedimentary rocks?
  15. (1980). Anoxic environments and oil source bed genesis.
  16. (2005). Assembling Stereo Anaglyph Images with Photoshop. Modern Microscopy Journal. Online Journal; World Wide Web address: http://www.modernmicroscopy.com
  17. (1984). Basin model for hemipelagic sedimentation in a tectonically active continental margin: Santa Barbara Basin, California Continental Borderland. Fine-Grained Sediments: In: Piper,
  18. (1991). Benthic foraminiferal population fluctuations related to anoxia: Santa Barbara Basin.
  19. (1948). Bibliographic index of Bohemian Silurian graptolites. Knihovna Statniho Geologickeho Ustavu Republiky
  20. (1987). Biogenic Sedimentary Fabrics Associated with Pioneering Polychaete Assemblages: Modern and Ancient.
  21. (1996). Biostratigraphical control of thrust models for the Southern Uplands of Scotland.
  22. (1967). Biostratigraphie und Taxionomie von Rastrites (Pterobranchiata, Graptolithina) aus dem anstehenden Silur Ostthüringens und des Vogtlandes. Freiberger Forschungsh., Paläont.
  23. (2003). Biostratigraphy, palaeobiogeography and morphology of the Llandovery graptolites Campograptus lobiferus (M‘Coy) and Campograptus harpago (Törnquist).
  24. (1995). Biotic crises and post-crisis recoveries recorded by graptolite faunas of the Barrandian area (Czech Republic).
  25. (1979). Bituminous shales and oolitic ironstones as indicators of transgressions and regressions.
  26. (1979). Black shale; its deposition and diagenesis.
  27. (2001). Black shales on the basin margin: a model based on examples from the Upper Jurassic of the Boulonnais, northern France. Sedimentary Geology,
  28. (1994). Black shales. Geology and Geophysics Monographs,
  29. (1980). British Lower Palaeozoic black shales and their palaeooceanographic significance.
  30. (1983). Burial of organic carbon and pyrite sulfur in sediments over phanerozoic time: a new theory.
  31. (2007). Campograptus clingani. In:
  32. (2007). Campograptus lobiferus. In:
  33. (2006). Carbon isotope chemostratigraphy in Arctic Canada: Sea-level forcing of carbonate platform weathering and implications for Hirnantian global correlation.
  34. (2006). Carbon isotope chemostratigraphy of the Llandovery in Arctic Canada: Implications for global correlation and sea-level change.
  35. (2004). Carbon isotope effects in carbonate systems.
  36. (1997). Carbon isotope stratigraphy of the Ordovician-Silurian Stratotype (Dob's Linn, Scotland) and its global correlation.
  37. (1998). Carbon-isotope analyses of fossil plants as a chemostratigraphic and palaeoenvironmental tool.
  38. (2007). Cephalograptus tubulariformis. In:
  39. (1996). Climate connections between the hemisphere revealed by deep sea sediment core/ice core correlations.
  40. (1996). Controls on the pyritization of exceptionally preserved fossils; an analysis of the Lower Devonian Hunsrueck Slate of Germany.
  41. (2007). Coronograptus gregarious gregarius. In:
  42. (1977). Cortical bandages and the graptolite zooid.
  43. (1984). Deep-water fine-grained sediments: facies models.
  44. (1980). Demirastrites pribyli Boucek,
  45. (1975). Depositional environments as interpreted from primary sedimentary structures and stratification sequences.
  46. (2008). Diagenetic rare earth elements remobilization in organic-rich black shales of Marvast,
  47. (1906). Die Anwendung der Rontgenstrahlen in der palaeontologie.
  48. (1938). Die Anwendung der Rontgenstrahlen in der palaontologie.
  49. (1978). Discoveries on graptolites by X-ray studies.
  50. (1961). Distribution of the Elements in some major units of the Earth's crust.
  51. (1988). Earliest Monograptidae (Graptolithina) in the lower Llandovery sequence of the Prague Basin,
  52. (1980). Early diagenesis: A theoretical approach.
  53. (1970). Early Silurian graptolites from southeastern Alaska and their correlation with graptolitic sequences
  54. (2007). Early Silurian positive delta C13 excursions and their relationship to glaciations, sea-level changes and extinction events.
  55. (1998). Early Silurian sea-level changes.
  56. (2002). Earth geography from 500 to 400 million years ago: a faunal and palaeomagnetic review.
  57. (1984). Effect of benthic mixing on the information content of deep-sea stratigraphical signals.
  58. (2006). Essentials for Dental Radiographers. World Wide Web Address.
  59. Etudes sur les Graptolites de Boheme. Pt 3. Monographie des Graptolites de l'Etage E. Section a.25 pp.,
  60. (1977). Evolution of the Silurian and Devonian graptoloids,
  61. (1985). Fine-grained sediments in deep water: An overview of processes and facies models.
  62. (1970). Fractionation of carbon and oxygen isotopes and magnesium between coexisting metamorphic calcite and dolomite. Contributions to Mineralogy and Petrology,
  63. (1992). Geochemical discrimination of Silurian mudstones according to depositional process and provenance within the Southern Welsh Basin: Review Meeting on the Welsh Basin.
  64. (1982). Geology of the country around Carrickfergus and Bangor (Counties Antrim and Down): memoir for one-inch geological sheet 29
  65. (2007). Geology of the Newcastle Emlyn district : a brief explanation of the geological map Sheet 211 Newcastle Emlyn British Geological Survey.
  66. (2008). Geosphere and biosphere dynamics during late ordovician climate change Earth sciences. PhD thesis,
  67. (1998). Graptolite biostratigraphy of the Lower Silurian (Llandovery) shelf deposits of the Western Iberian Cordillera,
  68. (2001). Graptolites as constraints on models of sedimentation across Iapetus: a review.
  69. (1998). Graptolites of the Pribylograptus leptotheca and Lituigraptus convolutus biozones of Tman (Silurian, Czech Republic). Casopis Ceske Geologicke Spolecnosti,
  70. (1990). Graptoloid biogeography; recent progress, future hopes.
  71. (2009). Graptoloid cladistics, taxonomy and phylogeny.
  72. (1998). Hemipelagites: processes, facies and model.
  73. (1997). History of water-column anoxia in the Black Sea indicated by pyrite framboid size distributions.
  74. (1991). How are they preserved? In
  75. (2008). Ichnological record of deep-sea palaeoenvironmental changes around the Oceanic Anoxic Event 2 (Cenomanian-Turonian boundary): An example from the Barnasiówka section, Polish Outer Carpathians.
  76. (2004). In situ growth of monazite in anchizonal to epizonal mudrocks: first record from the Variscan accretionary prism of the Kaczawa Mountains, West Sudetes, SW Poland.
  77. (1993). Influence of water column anoxia on the burial and preservation of carbon and phosphorus in marine shales.
  78. (1996). Insights into deposition of Lower Cretaceous black shales from meager accumulation of organic matter in Albian sediments from ODP site 763, Exmouth Plateau, Northwest Australia.
  79. (1999). Interpreting carbon-isotope excursions: carbonates and organic matter. Geochemistry of Organic-Rich Shales: New Perspectives,
  80. (2005). Investigating the record of Permian climate change from argillaceous sedimentary rocks,
  81. (1991). Isolated graptolites from the Llandovery of Kallholen,
  82. (2001). Isotope biogeochemistry of marine organic carbon.
  83. (2001). Isotopic evolution of the biogeochemical carbon cycle during the Precambrian. In:
  84. (1996). Laminated sediments as palaeo-indicators.
  85. Late Caradoc graptolitic faunal gradients across the Iapetus Ocean.
  86. (1991). Late Ordovician and early Silurian turbidite systems
  87. (2000). Late Ordovician to Silurian evolution of Eastern Avalonia during convergence with laurentia.
  88. (1922). Lead and Zinc. The mining district of north Cardiganshire and west montgomeryshire.
  89. (1948). Les graptolithes et quelques nouveaux groupes d'animaux du tremadoc de la Pologne; graptolity i pare nowych grup zwierzat z tremadoku Polski Panstwowe Wydawnictwo Naukowe.
  90. (1975). Llandoverian and Wenlockian graptolites from Bornholm Universitetsforlaget.
  91. (1994). Marine Black Shales: Depositional Mechanisms and Environments of Ancient Deposits.
  92. (1983). Measurement of thecal spacing in graptolites.
  93. (1990). Metabentonites in the Moffat Shale Group, Southern Uplands of Scotland: geochemical evidence of ensialic marginal basin volcanism.
  94. (2008). Microfacies, biostratigraphy, and geochemistry of the hemipelagic Barremian-Aptian
  95. (1991). Mid Silurian pelagic and hemipelagic sedimentology and palaeoceanography.
  96. (1994). Mineralogy and geochemistry of the Peterborough member,
  97. (1957). Minor internal structures of some recent unconsolidated sediments [Gulf of Mexico].
  98. (1991). Model for transgressive black shales?
  99. (1991). Modern and ancient continental shelf anoxia: an overview.
  100. (1993). Moffatdale and the upper Ettrick valley : description of the solid geology of parts of 1:25000 sheets NT10, 11, 20 and 21.
  101. (2006). Molecular taphonomy of graptolites.
  102. (1979). New observations on the mode of life, evolution and ultrastructure of graptolites.
  103. (1965). New Silurian graptolites from the Howgill Fells (northern England).
  104. (1942). O Petalolithech ze skupiny P. folium (His.) a o rodu Cephalograptus Hopk.
  105. (1941). O rodu Petalolithus Suess z ceskeho siluru. Rozpravy ceske Akademie,
  106. On Scottish Monograptidae.
  107. On the classification and nomenclature of the Lower Palaeozoic rocks of England and Wales.
  108. On the Graptolites described by Hisinger. Bihang till Kungliga Vetenskaps Akademie Handlinga,
  109. (1979). Ordovician and Silurian changes in sea level.
  110. (1990). Ordovician graptolite biostratigraphy in the Welsh Basin: a review.
  111. (2000). Organic carbon flux in an anoxic water column: sediment trap results from the Cariaco Basin. Limnology and Oceanography,
  112. (2004). Organic carbon proxies in black shales: molybdenum. Geochemistry of Organic-Rich Shales: New Perspectives,
  113. (1999). Organic-matter source variation and the expression of a late Middle Ordovician carbon-isotope excursion.
  114. (1991). Organism-sediment relationships in Silurian marine environments. In:
  115. (2005). Origin, sequence stratigraphy and depositional environment of an upper Ordovician (Hirnantian) deglacial black shale,
  116. (1998). Palaeoceanographic and Faunal Changes in the Early Silurian.
  117. (1984). Palaeoecology of graptolitic black shales. In: Bruton, D.L., Aspects of the Ordovician System; IV,
  118. (1975). Palaeoecology of the Graptolithinia, an extinct class of the phylum hemichordate.
  119. (2007). Palaeontology: Paleontologists Get X-ray Vision.
  120. (1997). Paleoenvironmental changes in the Silurian, indicated by stable isotopes in brachiopod shells from Gotland (Sweden).
  121. (1993). Population analysis and orientation studies of graptoloids from the Middle Ordovician Utica Shale,
  122. (2008). Prediction of atmospheric 13CO2 using fossil plant tissues.
  123. (2004). Preservation of soft tissues in Silurian graptolites from Latvia.
  124. (1987). Principles of Radiological Physics.
  125. (1968). Problems of electron stereoscopy of biological tissue
  126. (1976). Progressive faunal migration across the Iapetus Ocean.
  127. (1978). Progressive ventilation of the oceans; an explanation for the distribution of the lower Paleozoic black shales.
  128. (1985). Pyrite formation in euxinic and semi-euxinic sediments.
  129. (1998). Pyrite framboid diameter as a measure of oxygen deficiency in ancient mudrocks.
  130. (1982). Pyrite texture, isotopic composition and the availability of iron.
  131. (1969). Pyriterhaltung von Weichteilen bei devonischen Cephalopoden.
  132. (1991). Pyritization of soft-bodied fossils: Beecher's Trilobite Bed, Upper Ordovician,
  133. (1965). Radiographic techniques.
  134. (1913). Radiographs of Fossils. Scientific and Technical Exhibits, Natural History, Colour Prints, Lantern and Stereoscopic Slides.
  135. (2007). Rastrites hybridus hybridus. In:
  136. (2007). Rastrites peregrinus. In:
  137. (1991). Redistribution of rare earth elements during diagenesis of turbidite/hemipelagite mudrock sequences of Llandovery age from central Wales.
  138. Researches into the Monograptidae of the Scanian Rastrites Beds.
  139. (1979). Sedimentary environments of the basinal Llandovery of mid-Wales. In:
  140. (1970). Sedimentary pyrite formation.
  141. (2008). Sedimentation of the Phyllopod Bed within the Cambrian Burgess Shale Formation of British Columbia.
  142. (1996). Sequence stratigraphical analysis of late ordovician and early Silurian depositional systems in the Welsh Basin: a critical assessment.
  143. (1990). Silurian graptolite biostratigraphy in the Welsh Basin.
  144. (2003). Simple gifts and hidden treasures – Implications of finding bioturbation and erosion surfaces in black shales.
  145. (1970). Soft Parts of Cephalopods and Trilobites: Some Surprising Results of X-ray Examinations of Devonian Slates.
  146. (1969). Some thoughts on the ecology, mode of life and evolution of the Graptolithina.
  147. (2001). Southern Uplands geology: an historical perspective.
  148. (1973). Stereo Atlas of Ostracod shells.
  149. (2006). Synchrotron X-ray tomographic microscopy of fossil embryos.
  150. (1996). Tales of 1001 varves: a review of Santa Barbara Basin sediment studies.
  151. (1984). The "North American shale composite": Its compilation, major and trace element characteristics.
  152. (1974). The Black Sea-Geology, chemistry, and biology.
  153. (2000). The Early Palaeozoic geography of
  154. (1998). The fossils of the Hunsrück Slate: marine life in the Devonian. Cambridge Palaeobiology 3.
  155. (1999). The geochemistry of redox sensitive trace metals in sediments.
  156. (1991). The global biogeography of the Silurian period. In:
  157. (1968). The graptolite assemblages and zones of the Brikhill shales (lower Silurian) at Dobb's Linn.
  158. (1981). The graptolite biostratigraphy of a Llandovery outlier near Llanystumdwy, Gwynedd, North Wales.
  159. (1964). The graptolitic mudstone and associated facies in the Silurian strata of the Howgill Fells.
  160. (1965). The graptolitic mudstones of the Howgill F ells.
  161. (1909). The Hartfell-Valentian succession in the district around Plynlimon and Pont Erwyd (North Cardiganshire)
  162. (1970). The Llandovery (Silurian) graptolites of the Howgill Fells, northern England
  163. (1975). The Llandovery graptolites of the English Lake District, Part 2.
  164. (1974). The Llandovery graptolites of the English Lake District; Part 1.
  165. The Moffat Series.
  166. (1996). The nature of varved sedimentation in the Cariaco Basin, Venezuela, and its palaeoclimatic significance.
  167. (2008). The origins of graptolites and other pterobranchs: a journey from ‘Polyzoa’.
  168. (2004). The Phanerozoic Carbon Cycle.
  169. (1976). The sequence of Silurian graptolite zones in the British Isles.
  170. The Silurian rocks of Britain.
  171. The Silurian System.
  172. (1987). The Southern Uplands as an accretionary prism: the importance of analogues in reconstructing palaeogeography.
  173. (2001). The Southern Uplands Terrane: a stratigraphical review.
  174. (1968). The thecal form of some slender Llandovery Monograptus.
  175. (2001). The use of graptolites in the stratigraphy of the Southern Uplands: Peach’s legacy.
  176. (1945). The Valentian succession around Llanidloes, Montgomeryshire.
  177. Thuringische Graptolithen.
  178. (1993). to drive off residual atmospheric gases. The
  179. (2008). Tomographic techniques for the study of exceptionally preserved fossils.
  180. (1958). Triangulate monograptids from the Monograptus gregarius zone (lower Llandovery) of the Rheidol gorge (Cardiganshire).
  181. (2007). Tutorial: Radar and Stereoscopy. World Wide Web Address:
  182. Über Verwendung von Röntgenischen X-Strahlen zu paläontologische diagnostichen Zweken. Verhandlungen der Berliner physiologischen Gesellschaft.
  183. (2008). Ubiquitous Burgess Shale–style “clay templates” in low-grade metamorphic mudrocks.
  184. Undersökninger öfver Siljansområdets Graptoliter II.
  185. (1989). Unexpected changes in the oxic/anoxic interface in the Black Sea.
  186. (1992). Upper Aeronian and lower Telychian (Llandovery) graptolites from western mid-Wales The Palaeontographical Society monograph 146:
  187. (2002). Upper Homerian (Upper Wenlock, Silurian) graptolites from Arctic Canada.
  188. (1994). Uppermost Ordovician to Lower Silurian graptolite biostratigraphy of the Wye valley, central Wales.
  189. (1993). Using geochemical data: Evaluation, presentation, interpretation. Longman Scientific and Technical,
  190. (2001). Volcanically mediated plankton blooms in the Central Belt of the Southern Uplands, Scotland, during the Llandovery.
  191. (2007). Were transgressive black shales a negative feedback modulating glacioeustasy in the Early Palaeozoic Icehouse? In:
  192. (1991). Where are they found? In:
  193. (2004). X-ray imaging for palaeontology.

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.