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Volcanically mediated plankton blooms in the Central Belt of the Southern Uplands, Scotland, during the Llandovery

Published online by Cambridge University Press:  03 November 2011

S. Rigby  and
S. J. Davies
S. Rigby
Affiliation:
Susan Rigby, Department of Geology and Geophysics, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, U.K.
S. J. Davies
Affiliation:
Sarah J. Davies, Department of Geology, University of Leicester, University Road, Leicester LEI 7RH, U.K.
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Abstract

ABSTRACT

At Thirlestane Score and at four other localities in the Southern Uplands, graptolites of the Llandovery gemmatus Zone occur in couplets of lithologies immediately above thin ‘high-U’ bentonites. Above the bentonites, abundant graptolites, especially siculae, and a straight-line survivorship trend implies high productivity coupled with environmentally mediated mortality: the population structure expected in the early part of a plankton bloom. In the overlying facies, fewer, larger individuals and a convex survivorship curve suggest reduced productivity and internally mediated mortality. This is consistent with the later stages of a bloom where resources were waning but the ecological structure of the system was better developed. It is likely that the introduction of trace-metals, Fe or Al, to the water column via volcanic ash increased primary productivity, suggesting that macronutrients were available in the Southern Uplands system, allowing a bloom to be stimulated by the addition of volcanic products. This process is observed in modern open oceanic systems and implies a temporal continuity of control on the plankton despite complete faunal turn-over since the Silurian. These interpretations are most consistent with an open ocean geotectonic setting for the region.

Keywords

bentonitesgraptolitesLower Palaeozoicpalaeoceanography
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 91 , Issue 3-4: The Southern Uplands Terrane: Tectonics and Biostratigraphy within the Caledonian Orogen , 2000 , pp. 457 - 470
Copyright
Copyright © Royal Society of Edinburgh 2000

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References

Aldridge, R. J., Jeppsson, L. & Doming, K. 1993. Early Silurian oceanic episodes and events. Journal of the Geological Society, London 150, 501–13.CrossRefGoogle Scholar
Anderson, R. F. 1988. Concentration, vertical flux and mineralisation of particulate Uranium in seawater. Geochimica et Cosmochimica Acta 46, 1293–301.CrossRefGoogle Scholar
Barbed, F., Ferrara, G., Santacroce, R., Treuil, M. & Varet, J. 1975. A transitional basalt–pantellerite sequence of fractional crystallization the Boina Centre (A far Rift, Ethiopia). Journal of Petrology 16, 22–56.CrossRefGoogle Scholar
Blatt, H., Middleton, G. & Murray, R. 1980. Origin of Sedimentary Rocks. New Jersey: Prentice Hall.Google Scholar
Cooper, R. A., Fortey, R. A. & Lindholm, K. 1991. Latitudinal and depth zonation of early Ordovician graptolites. Lethaia 24, 199–218.CrossRefGoogle Scholar
Davis, A. G. 1967. Biological concentration of radiogenic iron in the western Pacific. In Aberg, B. & Hungate, F.P. (eds) Radioecological concentration processes, pp. 983–91. Oxford: Pergamon Press.CrossRefGoogle 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
Finney, S. C. & Berry, W. B. 1997. New perspectives on graptolite distributions and their use as indicators of platform margin dynamics. Geology 25, 919–22.2.3.CO;2>CrossRefGoogle Scholar
Fitton, J. G., Saunders, A. D., Larsen, L. M., Hadarson, B. S. & Norry, M. J. 1998. Volcanic rocks from the Southeast Greenland margin at 63°N: compositions, petrogenesis and mantle sources. In Saunders, A. D., Larsen, L. M., Clift, P. D. & Wise, S. W. J. (eds) Proceedings of the Ocean Drilling Program, Scientific Results 152, 331–50.Google Scholar
Fortey, R. A. & Cocks, L. R. M. 1986. Marginal faunal belts and their structural implications with examples from the Lower Palaeozoic. Journal of the Geological Society, London 143, 151–60.CrossRefGoogle Scholar
Frost, B. W. 1996. Phytoplankton bloom on iron rations. Nature 383, 475–6.CrossRefGoogle Scholar
Govindaraju, K. 1994. Compilation of working values and sample description for 383 geostandards. Geostandards Newsletters (Special Issue) 18.Google Scholar
Harper, H. E. & Knoll, A. H. 1975. Silica, diatoms and Cenozoic radiolarian evolution. Geology 3, 175–7.2.0.CO;2>CrossRefGoogle Scholar
Huff, W. D., Anderson, T. B., Rundle, C. C. & Odin, G. S. 1991. Chemostratigraphy, K—Ar ages and illitization of Silurian K-bentonites from the Central Belt of the Southern Uplands Down Longford Terrane, British Isles. Journal of the Geological Society, London 148, 861–8.CrossRefGoogle Scholar
Hutchinson, G. E. 1978. An introduction to population biology. New Haven & London: Yale University Press.Google Scholar
Jackson, G. A. & Morgan, J. J. 1978. Trace metal-chelator interactions and phytoplankton growth in seawater media: Theoretical analysis and comparison with reported observations. Limnology and Oceanography 23, 268–82.CrossRefGoogle Scholar
Jeppsson, L. 1990. An oceanic model for lithological and faunal changes tested on the Silurian record. Journal of the Geological Society, London 147, 663–74.CrossRefGoogle Scholar
Jochum, K. P., Seufert, H. M. & Thirlwall, M. F. 1990. High-sensitivity Nb analysis by spark-source mass spectrometry (SSMS) and calibration of XRF Nb and Zr. Chemical Geology 81, 1–16.CrossRefGoogle Scholar
Kolata, D. R., Frost, J. K. & Huff, W. D. 1987. Chemical correlation applied to K-bentonite beds in the Middle Ordovician Decorah Subgroup, upper Mississippi Valley. Geology 15, 208–11.2.0.CO;2>CrossRefGoogle Scholar
Lapworth, C. 1878. The Moffat Series. Quarterly Journal of the Geological Society, London 34, 240–346.CrossRefGoogle Scholar
Leggett, J. K., McKerrow, W. S. & Eales, M. H. 1979. The Southern Uplands of Scotland: a Lower Palaeozoic accretionary prism. Journal of the Geological Society, London 136, 755–70.CrossRefGoogle Scholar
Lovley, D.R., Phillips, E.J.P., Gorby, Y.A. & Landa, E.R. 1991. Microbial reduction of uranium. Nature 350, 413–16.CrossRefGoogle Scholar
Loydell, D. K. 1991. Dob's Linn-the type locality of the Telychian (Upper Llandovery) Rastrites maximus biozone? Newsletters in Stratigraphy 25, 155–61.CrossRefGoogle Scholar
Loydell, D. K. 1993. Upper Aeronian and Lower Telychian (Lland-overy) graptolites from western Mid-Wales. Palaeontographical Society Monograph 146, 1–55.CrossRefGoogle Scholar
Martin, R. E. 1996. Secular increase in nutrient levels through the Phanerozoic, implications for productivity, biomass and diversity of the marine biosphere. Palaios 11, 209–19.CrossRefGoogle Scholar
McDonough, W. F. & Sun, S-S. 1995. The composition of the Earth. Chemical Geology 120, 223–53.CrossRefGoogle Scholar
Merriman, R. J. & Roberts, B. 1990. Matebentonites in the Moffat Shale Group, Southern Uplands of Scotland: Geochemical evidence marginal basin volcanism. Geological Magazine 127, 259–71.CrossRefGoogle Scholar
Noji, T. T. 1991. The influence of macrozooplankton on vertical particular flux. Sarsia 76, 1–9.CrossRefGoogle Scholar
Parrish, J. T. 1982. Upwelling and petroleum source beds, with reference to the Palaeozoic. Bulletin of the American Association of Petroleum Geologists 66, 750–74.Google Scholar
Peach, B. N. & Horne, J. 1899. The Silurian Rocks of Britain, Volume 1: Scotland. Memoirs of the Geological Survey of the United Kingdom. Glasgow: HMSO.Google Scholar
Pearce, R. B. 1995. The geochemistry of Llandovery and Wenlock age K-Bentonites in the Southern Uplands. Scottish Journal of Geology 31, 23–8.CrossRefGoogle Scholar
Raymont, J. E. G. 1980. Plankton and productivity in the oceans. Oxford: Pergamon Press.Google Scholar
Reynolds, R. C. J. 1963. Matrix corrections in trace element analysis by X-ray fluorescence: estimation of the mass absorption coefficient by Compton scattering. American Mineralogist 48, 1133–43.Google Scholar
Rickards, R. B., Rigby, S. & Harris, J. H. 1990. Graptoloid biogeography: recent progress, future hopes. In McKerrow, W. S. & Scotese, C. R. (eds) Palaeozoic palaeogeography and biogeography. Geological Society, London, Memoir 12, 139–45.Google Scholar
Rigby, S. 1993. Population analysis and orientation studies of graptoloids from the Middle Ordovician Utica Shale, Quebec. Palaeontology 36, 267–82.Google Scholar
Rosenzweig, M. L. 1971. Paradox of enrichment: destabilisation of exploitation ecosystems in ecological time. Science 171, 385–7.CrossRefGoogle Scholar
Rushton, A. W. A. & Stone, P. 1991. Terrigenous input to the Moffat Shale Sequences, Southern Uplands. Scottish Journal of Geology 27, 167–9.CrossRefGoogle Scholar
Ryther, J. H. & Guillard, R. R. 1959. Enrichment experiments as a means of studying nutrients limiting to photoplankton populations. Deep-Sea Research 15, 47–61.Google Scholar
Stone, P., Floyd, J. D., Barnes, R. P. & Lintern, B. C. 1987. A sequential back-arc and foreland basin thrust duplex model for the Southern Uplands of Scotland. Journal of the Geological Society, London 144, 753–64.CrossRefGoogle Scholar
Stow, D. A. V., Reading, H. G. & Collinson, J. D. 1997. Deep Seas. In Reading, H. H. (ed.) Sedimentary Environments: Processes, Facies and Stratigraphy, pp. 395–453. Oxford: Blackwell Science.Google Scholar
Taylor, S. R. & McLennan, S. M. 1985. The Continental Crust: its Composition and Evolution. Oxford: Blackwell Scientific Publications.Google Scholar
Tranter, D. J. & Newel, B. S. 1963. Enrichment experiments in the Indian Ocean. Deep-Sea Research 10, 1–9.Google Scholar
Watson, J.A. 1997. Volcanic iron CO2, ocean productivity and climate. Nature 385, 587–8.CrossRefGoogle Scholar
Ziegler, A. M. & McKerrow, W. S. 1975. Silurian marine red beds. American Journal of Science 275, 31–56.CrossRefGoogle Scholar