Hostname: page-component-586b7cd67f-2plfb Total loading time: 0 Render date: 2024-11-20T07:21:37.089Z Has data issue: false hasContentIssue false
  • English
  • Français

Diagenetic controls on multiphase pyritization of graptolites

Published online by Cambridge University Press:  01 May 2009

Charlie J. Underwood  and
Simon H. Bottrell
Charlie J. Underwood
Affiliation:
Department of Geology, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK
Simon H. Bottrell
Affiliation:
Department of Earth Sciences, University of Leeds, Leeds LS2 9JT, UK
Get access Rights & Permissions [Opens in a new window]

Abstract

Observations on pyritized graptolites have revealed a variety of pyrite morphotypes, several of which often coexist within the same fossil steinkern. The commonest forms of pyrite are those consisting of size-sorted microcrysts, which show degrees of ordering ranging from well-ordered framboids to a more homogeneous, unordered groundmass. Larger, euhedral pyrite crystals may be scattered throughout the microcrystalline groundmass, or be the dominant pyrite form in themselves. ‘Floriform’ pyrite frequently overgrows earlier framboids and may act to mould the inner periderm microstructure of the graptolite. Overpyrite occurs either as a primary ‘overspill’ of internal pyrite, or as a separate, later phase.

All of the diagenetic pyrite has light sulphur isotope compositions, indicating formation during early diagenesis; isotopic evidence of the relative timing of pyrite generations matches the morphological paragenesis. Under most conditions, available iron appears not to be a limiting factor in pyrite formation, with reactive organic matter only being limiting at the lowest concentrations encountered in these sediments. The availability of organic matter does, however, exert a control on the timing of fossil pyritization. At one locality, a change in diagenetic conditions has allowed for the formation of a morphologically late generation of pyrite with isotopically light and therefore apparently early diagenetic signatures.

Type
Articles
Information
Geological Magazine , Volume 131 , Issue 3 , May 1994 , pp. 315 - 327
Copyright
Copyright © Cambridge University Press 1994

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Allison, P. A. 1988. Taphonomy of the Eocene London Clay biota. Palaeontology 31, 1079–1100.Google Scholar
Allison, P. A. 1990. Pyrite. In Paleobiology – a synthesis (eds D. Briggs, E. G. and Crowther, P. R., pp. 253–5. Blackwell.Google Scholar
Beier, J. A. & Feldman, H. R. 1991. Sulfur isotopes and paragenesis of sulphide minerals in the Silurian Waldron Shale, southern Indiana. Geology 19, 389–92.2.3.CO;2>CrossRefGoogle Scholar
Bergström, J. 1990. Hunsrück Slate. In Paleobiology – a synthesis (eds Briggs, D. E. G. and Crowther, P. R., pp. 277–9. Blackwell.Google Scholar
Berner, R. A. 1984. Sedimentary pyrite formation: an update. Geochimica et Cosmochimica Acta 48, 605–15.CrossRefGoogle Scholar
Berner, R. A. & Raiswell, R. 1984. C/S method for distinguishing freshwater from marine sedimentary rocks. Geology 12, 365–8.2.0.CO;2>CrossRefGoogle Scholar
Berry, W. B. N. 1989. Taphonomic influence on perception of the Late Ordovician mass mortality. Abstracts, 28th International Geological Congress, 1, 138.Google Scholar
Bjerreskov, M. 1978. Discoveries on graptolites by X ray studies. Acta Palaeontologica Polonica 23, 463–71.Google Scholar
Bjerreskov, M. 1991. Pyrite in Silurian graptolites from Bornholm, Denmark. Lethaia 24, 351–61.CrossRefGoogle Scholar
Briggs, D. E. G., Bottrell, S. H. & Raiswell, R. 1991. Pyritisation of soft-bodied fossils: Beecher's Trilobite Bed, Upper Ordovician, New York State. Geology 19, 1221–4.2.3.CO;2>CrossRefGoogle Scholar
Canfield, D. E. & Raiswell, R. 1991. Pyrite Formation and Fossil Preservation. In (eds Allison, P. A. and Briggs, D. E. G.), pp. 337–87. Taphonomy: Releasing the Data Locked in the Fossil Record. Plenum.Google Scholar
Canfield, D. E., Raiswell, R., Westrich, J. T., Reaves, C. M. & Berner, R. A. 1986. The use of chromium reduction in the analysis of reduced inorganic sulphur in sediments and shales. Chemical Geology 54, 149–55.CrossRefGoogle Scholar
Canfield, D. E., Raiswell, R. & Bottrell, S. H. 1992. The reactivity of sedimentary iron minerals toward sulfide. American Journal of Science 292, 659–83.CrossRefGoogle Scholar
Chambers, L. A. & Trudinger, P. A. 1979. Microbiological fractionation of stable sulphur isotopes. Geomicrobiology 1, 249–92.CrossRefGoogle Scholar
Claypool, G. W., Holser, W. T., Kaplan, I. R., Sakai, H. & Zak, I. 1980. The age curves of sulphur and oxygen and their mutual interpretation. Chemical Geology 28, 199–260.CrossRefGoogle Scholar
Coleman, M. L. 1980. Corrections for mass spectrometer analysis of sulphur dioxide. IGS isotope geology unit Stable Isotope Report no. 45.Google Scholar
Crowther, P. R. 1981. The fine structure of graptolite periderm. Special Papers in Palaeontology no. 26.Google Scholar
Dimberline, A. J., Bell, A. & Woodcock, N. H. 1990. A laminated hemipelagic facies from the Wenlock and Ludlow of the Welsh Basin. Journal of the Geological Society, London 147, 693–701.CrossRefGoogle Scholar
Fisher, I. 1986 a. Pyrite replacement of mollusc shells from the Lower Oxford Clay (Jurassic) of England. Sedimentology 33, 575–85.CrossRefGoogle Scholar
Fisher, I. 1986 b. Pyrite formation in bioturbated clays from the Jurassic of Britain. Geochimica et Cosmochimica Acta 50, 517–23.CrossRefGoogle Scholar
Goldhaber, M. B. & Kaplan, I. R. 1980. Mechanisms of sulphur incorporation and isotopic fractionation during early diagenesis in sediments of the Gulf of California. Marine Chemistry 9, 95–143.CrossRefGoogle Scholar
Hudson, J. D. 1978. Pyrite in ammonite shells and in shales. Neues Jarbuch für Geologie und Paläontologie, Abhandlungen 159, 190–3.Google Scholar
Hudson, J. D. 1982. Pyrite in ammonite bearing clays from the Jurassic of England and Germany. Sedimentology 29, 637–67.CrossRefGoogle Scholar
Hughes, R. A. 1989. Llandeilo and Caradoc graptolites of the Builth and Shelve inliers. Palaeontographical Society Monograph, 89 pp.Google Scholar
Hutt, J. 1974–1975. The Llandovery graptolites of the English Lake District. Palaeontographical Society Monograph.CrossRefGoogle Scholar
Jenkins, C. J. 1987. The Ordovician graptiloid Didymograptus murchisoni in South Wales and its use in absolute strain analysis. Transactions of the Royal Society of Edinburgh, Earth Sciences 18, 105–14.CrossRefGoogle Scholar
Kalliokoski, J. 1966. Diagenetic pyritisation in three sedimentary rocks. Economic Geology 61, 872–85.CrossRefGoogle Scholar
Kemp, A. E. S. 1991. Mid Silurian pelagic and hemipelagic sedimentation and palaeoceanography: In The Murchison Symposium (eds Bassett, M. G., Lane, P. D. and Edwards, D.), pp. 261–301. Special Papers in Palaeontology no. 44.Google Scholar
Kenrick, P. & Edwards, D. 1988. The anatomy of Lower Devonian Glossingia breconensis Heard based on pyritised axes, with some comments on the permineralisation process. Botanical Journal of the Linnean Society 97, 95–123.CrossRefGoogle Scholar
Legget, J. K. 1980. British Lower Palaeozoic black shales and their palaeo-oceanographic significance. Journal of the Geological Society, London 137, 139–56.CrossRefGoogle Scholar
Legget, J. K., McKerrow, W. S., Cocks, L. R. M. & Rickards, R. B. 1981. Periodicity in the early Palaeozoic marine realm. Journal of the Geological Society, London 138, 167–76.CrossRefGoogle Scholar
Lenz, A. C. & Melchin, M. J. 1987. Peridermal and interthecal tissue in Silurian retiolitid graptolites: with examples from Sweden and Arctic Canada. Lethaia 20, 353–9.CrossRefGoogle Scholar
Leventhal, J. S. 1983. An interpretation of carbon and sulphur relationships in Black Sea sediments as indicators of environments of deposition. Geochimica et Cosmochimica Acta 47, 133–8.CrossRefGoogle Scholar
Love, L. G. 1971. Early diagenetic polyframboidal pyrite, primary and redeposited, from the Wenlockian Denbigh Grit Group, Conway, North Wales, U. K. Journal of Sedimentary Petrology 41, 1038–44.Google Scholar
Love, L. G. & Amstutz, G. C. 1966. Review of microscopic pyrite from the Chattanooga Shale and Rammelsberg Banderz. Fortschritte der Mineralogie 43, 273–309.Google Scholar
Love, L. G., Curtis, C. D. & Brockley, H. 1971. Framboidal pyrite: morphology revealed by electron microscopy of external surfaces. Fortschritte der Mineralogie 48, 259–64.Google Scholar
Raiswell, R., Buckley, F., Berner, R. A. & Anderson, T. F. 1988. Degree of pyritisation of iron as an indicator of bottom-water oxygenation. Journal of Sedimentary Petrology 58, 812–19.Google Scholar
Rickard, D. T. 1970. The origin of framboids. Lithos 3, 269–73.CrossRefGoogle Scholar
Rickards, R. B. 1967. The Wenlock and Ludlow succession in the Howgill Fells (north-west Yorkshire and West-morland). Quarterly Journal of the Geological Society of London 123, 215–51.CrossRefGoogle Scholar
Rickards, R. B. 1970. The Llandovery (Silurian) graptolites of the Howgill Fells, Northern England. Palaeontographical Society Monograph.Google Scholar
Rickards, R. B. & Stait, B. A. 1984. Psigraptus, its classification, evolution and zooid. Alcheringa 8, 101–12.CrossRefGoogle Scholar
Rickards, R. B., Partridge, P. L. & Banks, M. R. 1991. Psigraptus jacksoni Rickards and Stait – systematics, reconstruction, distribution and preservation. Alcheringa 15, 243–54.CrossRefGoogle Scholar
Robinson, B. W. & Kusakabe, M. 1975. Quantitative preparation of sulphur dioxide for 32S/34S analysis by combustion with cuprous oxide. Analytical Chemistry 47, 1179–81.CrossRefGoogle Scholar
Sassano, G. P. & Schrijver, K. 1989. Framboidal pyrite: early-diagenetic, late-diagenetic and hydrothermal occurrences from the Acton Vale Quarry, Cambro-Ordovician, Quebec. American Journal of Science 289, 167–79.CrossRefGoogle Scholar
Siveter, D. J., Owens, R. M. & Thomas, A. T. 1989. Silurian field excursions. A geotraverse across Wales and the Welsh Borderlands. National Museum of Wales/Geological Association, 133 pp.Google Scholar
Spjeldnaes, N. 1963. Some upper Tremadocian graptolites from Norway. Palaeontology 6, 121–31.Google Scholar
Stürmer, W. & Bergström, J. 1973. New discoveries on trilobites by X rays. Paläontologische Zeitschrift 47, 104–41.CrossRefGoogle Scholar
Sudbury, M. 1958. Triangulate monograptids from theMonograptus gregarius Zone of the Reidol Gorge. Philosophical Transactions of the Royal Society of London B 241, 485–555.Google Scholar
Underwood, C. J. 1992. Graptolite preservation and deformation. Palaiosl, 178–86.CrossRefGoogle Scholar