Facies

, Volume 43, Issue 1, pp 1–38 | Cite as

Development of facies and C/O-isotopes in transects through the Ludlow of Gotland: Evidence for global and local influences on a shallow-marine environment

  • Christian Samtleben
  • Axel Munnecke
  • Torsten Bickert
Article

Summary

The Silurian of Gotland is characterized by repeated changes in depositional facies development. The deposition of uniform sequences of micritic limestones and marls was interrupted four times by the growth of reef complexes and the formation of expanded carbonate platforms. Coinciding with these, often abrupt, facies changes extinction events occurred which predominantly affected nektonic and planktonic organisms. Ratios of carbon- and oxygen-isotopes covary with the facies development. Periods in which the deposition of limestonemarl alternations prevailed are characterized by relatively low C- and O-isotope values. During periods of enhanced reef growth isotope values are high. For these changes,Bickert et al. (1997) assume climatic changes between humid “H-periods”, with estuarine circulation systems and cutrophic surface waters with decreased salinity in marginal seas, and arid “A-periods”, with an antiestuarine circulation and oligotrophic, stronger saline surface waters.

In order to separate local and regional influences on the isotopic development from the global trend, the interactions between facies formation and isotope record have to be clarified. For this purpose, the patterns of isotope values in the upper part of the Silurian sequence on Gotland (upper Wenlock —upper Ludlow) has been determined and stratigraphically correlated along four transects through different facies areas. Facies formation during this time interval was investigated by differentiation and mapping of twelve facies complexes in the southern part of Gotland. These include shelf areas, reef complexes with patch reefs and biostromes, backreef facies, and marginal-marine deposits. The good correspondence between the carbon-isotope records of the four transects suggests that local environmental conditions in the different facies areas did not influence the δ13C values. Therefore, a supra-regional or even global mechanism for the C-isotope variations is likely.

In contrast to carbon istopes, the oxygen-isotope values of the four transects generally show parallel trends, but higher variabilities and in parts distinctly deviating developments with a trend to more negative values. These are interpreted as an effect of local warming in small shallow-water areas which developed during arid periods in reef complexes and backreef areas.

The boundaries between A-periods and H-periods, as defined by δ13C values, which are interpreted as isochrones, can be mapped. From the upper Homerian to the Pridolian six parastratigraphic isotope zones are defined which only partly match the stratigraphic division ofHede (1942, 1960). The isotope stratigraphy results in an improved correlation between the shallow and marginal-marine areas in the eastern part of Gotland and the uniform shelf areas at the west coast of the island.

Furthermore, a detailed relationship between the development of carbon and oxygen isotope ratios, the carbonate facies formation, and the succession of palaeontological events could be observed. At the transition from H-periods to A-periods, major extinction events occurred prior to the first increase of δ13C and δ18O values. Extinction events affected conodonts, graptolites, acritarchs, chitinozoans, and vertebrates and resulted in impoverished nektonic and planktonic communities. The reef-building benthos was less affected. Parallel to a first slight increase of isotope values, facies began to change, and reefs developed in suitable locations. The subsequent rapid increase of C- and O-isotope values occurred contemporarily with strong facies changes and a short-term drop of sea-level. Oligotrophic conditions in the later stages of A-periods led to strong reef growth and to an expansion of carbonate platforms.

The transitions from A-periods to H-periods were more gradual. The δ13C values decreased slowly, but reef growth continued. Later the reefs retreated and were covered by the prograding depositional facies of shelf areas. The diversity of planktonic and nektonic communities increased again.

The close relationship between facies formation, palaeontological events and isotope records in the Silurian suggests common steering mechanisms but gives no indication of the causes for the repeated extincion events related to H-period/A-period transitions. Especially the observation, that strong extinctions occurred prior to changes of isotope values and facies, points to causes that left no signals in the geological record. Hypothetical causes like collapse of trophical nets, anoxias, or cooling events are not evident in the sediment record or do not fit into the regular succession of period transitions.

Keywords

Facies Development Stable Isotopes Stratigraphy Palaeoceanography Gotland Silurian (Ludlow) 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Azmy, K., Veizer, J., Bassett, M.G. &Copper, P. (1998): Oxygen and carbon isotopic composition of Silurian brachiopods: Implications for coeval seawater and glaciations.—Geol. Soc. Amer. Bull.,110, 1499–1512CrossRefGoogle Scholar
  2. Bassett, M.G., Kaljo, D. &Teller, L. (1989): The Baltic region.— Nat. Mus. Wales, Geol. Ser.,9, 158–170Google Scholar
  3. Bickert, T., Pätzold, J., Samtleben, C. &Munnecke, A. (1997): Paleoenvironmental changes in the Silurian indicated by stable isotopes in brachiopod shells from Gotland, Sweden.— Geochimica et Cosmochimica Acta61, 2717–2730CrossRefGoogle Scholar
  4. Bickert, T. &Wefer, G. (1999): South Atlantic and benthic formanifer δ13C - deviations: Implications for reconstructing the Late Quaternary deep-water circulation.—Deep-Sea Res.,46, 137–452Google Scholar
  5. Brenchley, P. J. (1988): Environmental changes close to the Ordivician-Silurian boundary.—In:Cocks, L.R.M. & Rickards R.B. (eds.), A global Analysis of the Ordovician-Silurian Boundary.—Brit. Mus. (Nat. Hist.) Bull,43 (Geol. Ser.), 177–385Google Scholar
  6. Brenchley, P. J., Carden, G.A.F., &Marshall, J.D. (1995): Environmental changes associated with the “first strike” of the late Ordovicium mass extiriction.—Modern Geol.,20, 19–82Google Scholar
  7. Brood, K. (1976): Bryozoan palaeoecology in the Late Silurian of Gotland.—Palaeogeogr., Palaeoclimatol., Palaeoecol.,20, 187–208CrossRefGoogle Scholar
  8. Calner, M. (1999a): Stratigraphy, facies development and depositional dynamics of the Late Wenlock Fröjel Formation, Gotland, Sweden.—Geologiska Föreningens Förhandlingar,121, 13–24Google Scholar
  9. — (1999b): Comments to the mid-late Homerian (Silurian) sealevel curve.—Lund Publ. Geol.,144, p. 1Google Scholar
  10. Calner, M. &Jeppsson, L. (1999): Emersion and subaerial exposure in the Silurian of Gotland—response to a mid-Homerian glaciation.—GFF,121, 78–79Google Scholar
  11. Calner, M. &Säll, E. (1999): Transgressive oolites onlapping a Silurian rocky shoreline unconformity, Gotland, Sweden.— Geologiska Föreningens Förhandlingar,121, 91–10Google Scholar
  12. Cherns, L. (1982): Palaeokarst, tidal erosion surfaces and stromatolites in the Silurian Eke Formation of Gotland, Sweden.— Sedimentology,29, 119–833CrossRefGoogle Scholar
  13. — (1983): The Hemse-Eke boundary: facies relationships in the Ludlow Series of Gotland, Sweden.—Sveriges Geologiska Undersökning Ser. C,800, 1–45Google Scholar
  14. Corfield, R.M., Siveter, D.J., Cartlidge, J.E. &McKerrow, W.S. (1992): Carbon isotope excursion near the Wenlock-Ludlow (Silurian) boundary in the Anglo-Welsh area.—Geology,20, 371–374CrossRefGoogle Scholar
  15. Frykman, P. (1985): Subaerial exposure and cement stratigraphy of a Silurian bioherm in the Klinteberg Beds, Gotland, Sweden.— Geologiska Föreningens. Förhandlingar,107, 17–88Google Scholar
  16. — (1989): Carbonate ramp facies of the Klinteberg Formation, Wenlock—Ludlow transition on Gotland, Sweden.—Sveriges Geologiska Undersökning, C820, 1–79Google Scholar
  17. Harland B., Armstrong, L.L., Cox A.V., Craig, L.E., Smith A.G. &Smith, D.G. (1990): A geologic time scale 1989.—pp. 263, Cambridge (Cambridge University Press)Google Scholar
  18. Hede, J.E. (1921): Gottlands Silurstratigrafi.—Sveriges Geologiska Undersökning, Ser. C,305, 1–100Google Scholar
  19. Hede, J.E. (1925): Berggrunden (Silursystemet).—In:Munthe, H., Hede, J.E. & von Post, L.: Beskrivning till kartbladet Ronehamn.,— Sveriges Geologiska Undersökning, Aa156, 14–51Google Scholar
  20. Hede, J.E. (1927a): Berggrunden (Silursystemet).—In:Munthe, H., Hede, J.E. & Lundquist, G.: Beskrivning till kartbladet Klintehamn.— Sveriges Geologiska Undersökning, Aa160, 12–48Google Scholar
  21. Hede, J.E. (1927b): Berggrunden (Silursystemet).—In:Munthe, H., Hede. J.E. & Lundquist, G.: Beskrivning till kartbladet Hemse.— Sveriges Geologiska Undersökning, Aa164, 15–56Google Scholar
  22. Hede, J.E. (1928): Berggrunden (Silursystemet).—In:Munthe, H., Hedf, J.E. & Lundquist, G.: Beskrivning till kartbladet Slite.—Sveriges Geologiska Undersökning, Aa169, 13–65Google Scholar
  23. Hede, J.E. (1929): Berggrunden (Silursystemet).—In:Munthe, H., Hede, J.E. & Lundquist, G.: Beskrivning till kartbladet Katthammarsvik.— Sveriges Geologiska Undersökning, Aa170: 14–57Google Scholar
  24. — (1942): On the correlation of the Silurian of Gotland.—Meddel. Lunds Geol.-Miner. Inst.,101, 1–25Google Scholar
  25. Hede, J.E. (1960) The Silurian of Gotland. Guide to excursions A22 and C17.-21st Internat. Geol. Congress Copenhagen. pp. 44–89Google Scholar
  26. House, M. R. (1985): Correlation of mid-Palaeozoic ammonoid evolutionary events with global sedimentary perturbations.— Nature,313, 17–22CrossRefGoogle Scholar
  27. Jaeger, H. (1991): Neue Standard-Graptolithenzonenfolge nach der “Großen Krise” an der Wenlock/Ludlow-Grenze (Silur).— N. Jb. Geol. Paläont., Abh.,182, 103–354.Google Scholar
  28. Jeppsson, L. (1987): Lithological and conodont distributional evidence for episodes and anomalous oceanic conditions during the Silurian.—In:Aldridge, R.J. (ed.): Palaeobiology of Conodonts. —129–145, Chichester (Ellis Horwood)Google Scholar
  29. — (1990): An oceanie model for lithological and faunal changes tested on the Silurian record.—J. Geol. Soc. London,147, 663–674Google Scholar
  30. — (1993): Silurian events: the theory and the conodonts.—Proc. Estonian Acad. Sci.,42, 13–27Google Scholar
  31. Jeppsson, L. (1994): A new standard Wenlock conodont zonation.—In:Schönlaub, H.P. & Kreutzer, L.H. (eds.): IUGS Subcommision on Silurian Stratigraphy—Field Meeting Eastern & Southern Alps. Austria.—Ber. Geol. Bundes-Anst.,30, p. 133Google Scholar
  32. — (1997): The anatomy of the mid-Early Silurian Ireviken Event and a scenario for P-S Events.—In:Breit, C.E. &Baird, G. (eds.): Paleontological Event Horizons—Ecological and Evolutionary Implications.—451–492, New York Columbia University Press)Google Scholar
  33. Jeppsson, L. (1998): Silurian Oceanic Events: Summary of General Characteristices.— In:Landing, E. & Johnson, M.E. (eds.): Silurian Cycles: Linkages of dynamic stratigraphy with atmospheric, oceanic and tectonic changes.—James Hall Centennial Volume, New York State Mus.Bull.,491, 139–257Google Scholar
  34. Jeppsson, L., Aldridge, R.J. &Dorning, K.J. (1995): Wenlock (Silurian) oceanic episodes and events.—J. Geol. Soc. London,152, 187–498Google Scholar
  35. Jeppsson, L. &Männik, P. (1993): High resolution correlations between Gotland and Estonia near the base of the Wenlock.— Terra Nova,5, 348–358Google Scholar
  36. Jeppsson, L., Vira, V. &Männik, P. (1994): Silurian conodont-based correlations between Gotland (Sweden) and Saaremaa (Estonia). —Geol. Mag.,131/2, 101–218CrossRefGoogle Scholar
  37. Johnson, M.E., Cocks, L.R.M. &Copper, P. (1981): Late Ordovician-Early, Silúrian fluctuations in sea level from eastern Anticosti Island, Quebec.—Lethaia,14, 13–82Google Scholar
  38. Johnson, M.E. (1996): Stable cratonic sequences and a standard for Silurian custasy.—In:Witzke, B.J., Ludvigson, G.A. & Day, J. (eds.): Paleozoic sequence stratigraphy: views from the North American craton.—Geol. Soc. Amer., Special Paper,306, 103–211Google Scholar
  39. Johnson, M.E., Kalio, D. &Rong, J.-Y. (1991): Silurian eustasy.— Special Papers Palaeontology,44, 145–163Google Scholar
  40. Kaljo, D., Boucot, A.J., Corfield, R.M., Le Herissé, A., Koren, T.N., Kriz, J., Männik, P., Märss, T., Nestor, V., Shaver, R.H., Siveter, D.J. &Vitra, V. (1995): Silurian Bio-Events.— In:Walliser, O.H. (ed.): Global Events and Event Stratigraphy in the Phanerozoic.—173–223, Berlin (Springer)Google Scholar
  41. Kalio, D., Kipli, T. &Martma, T. (1997): Carbon isotope event markers through the Wenlock-Pridoli sequence at Ohesaare (Estonia) and Priekule (Latvia).—Palaeogeogr., Palaeoclimatol., Palaeoecol.,132, 111–223Google Scholar
  42. Kaljo, D., Kiipli, T. & Martma, T. (1998): Correlation of Carbon Isotope Events and Environmental Cyclicity in the East Baltic Silurian.—In:Landing, E. & Jounson M.E. (eds.): Silurian Cycles: Linkages of Dynamic Stratigraphy with Atmospheric. Oceanic and Tectonic Changes.—James Hall Centennial Volume, New York State Mus. Bull.,491, 197–312Google Scholar
  43. Kano, A. (1989): Deposition and Palaeoecology of an Upper Silurian stromatoporoid reef on southernmost Gotland.—Geol. Jour.,24, 195–315.Google Scholar
  44. Keeling, M. &Kershaw, S. (1994): Rocky shore environments in the Upper Silurian of Gotland, Sweden.—Geologiska Föreningens Förhandlingar.,116, 19–74Google Scholar
  45. Kershaw, S. (1987): Stromatoporoid-coral intergrowths in a Silurian Biostrome.—Lethia.20, 371–380Google Scholar
  46. Kershaw, S. (1993): Sedimentation control on growth of stromatoporoid reefs in the Silurian of Gotland, Sweden.—J. Geol. Soc. London,150, 197–205Google Scholar
  47. Kershaw, S. &Keeling, M. (1994): Factors controlling the growth of stromatoporoid biostromes in the Ludlow of Gotland, Sweden.— Sed. Geol.,89, 125–335CrossRefGoogle Scholar
  48. Koren, T.N., Lenz, A.C., Loydell, D.K., Melchin, M.J., Storch, P. &Teller, L. (1996): Generalized graptolite zonal sequence defining Silurian time intervals for global paleogeographic studies.—Lethaia,29, 19–60Google Scholar
  49. Laufeld, S. (1974a): Silurian Chitinozoa from Gotland.—Fossils and Strata,5, 1–130Google Scholar
  50. — (1974b): Reference localities for palaeontology and geology in the Silurian of Gotland.—Sveriges Geologiska Undersökning, C705, 1–172Google Scholar
  51. Laufeld, S. &Bassett, M.G. (1981): Gotland: the anatomy of a Silurian carbonate platform.—Episodes,2, 13–27Google Scholar
  52. Loydell, D.K. (1998): Early Silurian sea-level changes.—Geol. Mag.,135, 147–471Google Scholar
  53. Manten, A.A. (1971): Silurian reefs of Gotland.—Developments in Sedimentology,13, 1–539, Amsterdam (Elsevier)Google Scholar
  54. Martinsson, A. (1965): The Siluro-Devonian Ostracode genusNodibeyrichia and faunally assiciated kloedenines.—Geologiska Föreningens Förhandlingar,87, 109–138Google Scholar
  55. — (1967): The succession and correlation of ostracode faunas in the Silurian of Gotland.—GFF,89, 150–386Google Scholar
  56. McGhee, G.R., Bayer, U. &Seilacher, A. (1991): Biological and evolutionary responses to transgressive-regressive cycles.—In:Einsele, G., Ricken, W. &Seilacher, A. (eds.): Cycles and Events in Stratigraphy.—696–708, Berlin (Springer)Google Scholar
  57. McKerrow, W.S. (1979): Ordovician and Silurian changes in sea level.—J. Geol Soc. London,136, 137–145Google Scholar
  58. Munnecke, A. &Samtleben, C. (1996): The formation of micritic limestones and the development of limestone-marl alternations in the Silurian of Gotland, Sweden.—Facies,34, 159–176Google Scholar
  59. Munnecke, A., Westphal, H., Reijmer, J.J.G. &Samtleben, C. (1997): Microspar development during early marine burial diagenesis: a comparison of Pliocene carbonates from the Bahamas with Silurian limestones from Gotland (Sweden).— Sedimentology,44, 977–990Google Scholar
  60. Munthe, H. (1921): Beskrivning till karbladet Burgsvik jämte Hoburgen och Ytterholmen.—Sveriges Geologiska Undersökning Aa,152, 1–172Google Scholar
  61. Riding, R. (1981): Composition, structure and environmental setting of Silurian bioherms and biostromes in northern Europe.—In:Toomey, D.F. (ed.): European Fossil Reef Models.—Society of Economic Plaeontologists and Mineralogists, Spec. Publ., 30, 11–83Google Scholar
  62. Samtleben, C., Munnecke, A., Bickert, T. &Pätzold, J. (1996): The Silurian of Gotland (Sweden): facies interpretation based on stable isotopes in brachiopod shells.—Geologische Rundschau,85, 178–292CrossRefGoogle Scholar
  63. Samtleben, C., Munnecke, A., Bickert, T. & Pätzold, J. (in press): Shell succession, assemblage, and species dependent effects on the C/O-isotopic composition of brachiopods—examples from the Silurian of Gotland.—Chemical GeologyGoogle Scholar
  64. Schönlaub, H.P. (1986): Significant geological events in the Paleozoic record of the Southern Alps (Austrian Part).—In:Walliser, O.H. (ed.): Global Bio-events.—163–167 Berlin (Springer)Google Scholar
  65. Stel, J.H. &de Coo, J.C.M. (1977): The Silurian Upper Burgsvik and Lower Hamra-Sundre Beds, Gotland.—Scripta Geol.,44, 1–43Google Scholar
  66. Sundquist, B. (1982a): Wackestone petrography and bipolar orientation of cephalopods as indicators of littoral sedimentation in the Ludlovian of Gotland.—Geologiska Föreningens Förhandlingar,104, 11–90Google Scholar
  67. — (1982b): Palaeobathymetric interpretation of wave ripple-marks in a Ludlovian grainstone of Gotland.—Geologiska Föreningens Förhandlingar.,104, 157–166Google Scholar
  68. Talent, J.A., Mawson, R., Andrew, A.S., Hamilton, P.J. &Whitford, D.J. (1993): Middle Palaeozoic extinction events: Faunal and isotopic data.—Palaeogeogr., Palaeoclimatol., Palaeoecol.,104, 139–152CrossRefGoogle Scholar
  69. Tucker, R.D. &McKerrow, W.S. (1995): Early Paleozoic chronology: a review in light of new U-Pb zircon ages from Newfoundland and Britain.—Canad. J. Earth Sci.,32, 368–379Google Scholar
  70. Wenzel, B. &Joachimski, M.M. (1996): Carbon and oxygen isotopic composition of Silurian brachiopods (Gotland/Sweden): paleoceanographic implications.—Palaeogeogr., Palaeoclimatol., Palaeoecol.,122, 143–166CrossRefGoogle Scholar
  71. Wilde, P., Berry, W.B.N. &Quinby-Hunt, M.S. (1991): Silurian oceanic and atmospheric circulation and chemistry.—Spec. Papers Paleont.,44, 123–143Google Scholar
  72. Wilson, J.L. (1975): Carbonate Facies in Geologic History.—471 pp., Berlin (Springer).Google Scholar

Copyright information

© Institut für Paläontologie, Universität Erlangen 2000

Authors and Affiliations

  • Christian Samtleben
    • 1
  • Axel Munnecke
    • 2
  • Torsten Bickert
    • 3
  1. 1.Institut für Geowissenschaften (Geologie)Universität KielKiel
  2. 2.Institut für Geologie und PaläontologieUniversität TübingenTübingen
  3. 3.Fachbereich GeowissenschaftenUniversität BremenBremen

Personalised recommendations