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Preliminary report on the geochemistry and mineralogy of the Nod Glas and related sediments (Ordovician) of Wales

Published online by Cambridge University Press:  01 May 2009

J. T. Temple  and
R. Cave
J. T. Temple
Affiliation:
Birkbeck College, Malet Street, London WC 1E 7HX, U.K.
R. Cave
Affiliation:
University College of Wales, Aberystwyth, Dyfed SY23 3DB, U.K.
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Abstract

Preliminary results are reported of geochemical and mineralogical studies on the Nod Glas sediments of Caradoc age (clingani-linearis biozones) in Wales. Results are based on sampling at three localities in North Wales, together with a coeval section in South Wales. Data have been obtained for 21 elements by ICPAES, and for organic C, S and ignition loss. XRD analysis has provided semi-quantitative data on abundances of muscovite 2M1, quartz, albite and chlorite. Mean values of K2O, organic C, S, Cu, Zr and Ba are higher in the Nod Glas than in adjacent strata, while Fe203, MnO, MgO, CaO and P205 are lower. Analogy with the chemical composition of modern sediments reinforces the interpretation of the Nod Glas as being deposited under dysaerobic to anaerobic bottom conditions. There is considerable variation in composition between different Nod Glas sections. Analysis of mineral/chemical relationships shows some consistencies: for example, chlorite shows significant positive correlations with the heavier transition elements Mn to Zn, as well as with Li and Mg, presumably due to enrichment by adsorption of these elements onto subsequently recrystallized smectites. Other relationships are less consistent: organic C is correlated with muscovite (where it is probably held in interlayer sites as a relic from a smectite precursor) and sometimes also with albite. Inconsistencies between the sections in mineral/element interrelations may be due to diagenetic/metamorphic changes.

Type
Articles
Information
Geological Magazine , Volume 129 , Issue 5 , September 1992 , pp. 589 - 594
Copyright
Copyright © Cambridge University Press 1992

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References

Aagaard, P., Egeberg, P. K. & Smalley, P. C. 1989. Diagenetic reactions in Leg 104 sediments inferred from isotope and major element chemistry of interstitial waters. Proceedings of the Ocean Drilling Program, Scientific Results 104, 273–79.Google Scholar
Bailey, S. W. 1984. Crystal chemistry of the true micas. Reviews in Mineralogy 13, 13–60.Google Scholar
Bailey, S. W. 1988. Chlorites: structures and crystal chemistry. Reviews in Mineralogy 19, 347–403.Google Scholar
Bonatti, E., Fisher, D. E., Joensuu, O. & Rydell, H. S. 1971. Postdepositional mobility of some transition elements, phosphorus, uranium and thorium in deep sea sediments. Geochimica et Cosmochimica Acta 35, 189–201.CrossRefGoogle Scholar
Cave, R. 1965. The Nod Glas sediments of Caradoc age in North Wales. Geological Journal 4, 279–98.CrossRefGoogle Scholar
Chasteen, N. D. 1981. Vanadyl(IV) EPR spin probes: inorganic and biochemical aspects. In Biological magnetic resonance, vol. 3 (eds Berliner, L. J. and Reuben, J.), pp. 53–119. New York, London: Plenum Press.CrossRefGoogle Scholar
Chasteen, N. D. 1983. The biochemistry of vanadium. Structure and Bonding 53, 105–38.CrossRefGoogle Scholar
Chester, R. 1990. Marine Geochemistry. London: Unwin Hyman, xviii + 698 pp.CrossRefGoogle Scholar
Chester, R. & Aston, S. R. 1976. The geochemistry of deep-sea sediments. In Chemical Oceanography, vol. 6, 2nd ed. (eds Riley, J. P. and Chester, R.), pp. 281–414. London: Academic Press.CrossRefGoogle Scholar
François, R. 1988. A study of the regulation of the concentrations of some trace metals (Rb, Sr, Zn, Pb, Cu, V, Cr, Ni, Mn and Mo) in Saanich Inlet sediments, British Columbia, Canada. Marine Geology 83, 285–308.CrossRefGoogle Scholar
Heggie, D., Kahn, D. & Fischer, K. 1986. Trace metals in metalliferous sediments, MANOP Site M: interfacial pore water profiles. Earth and Planetary Science Letters 80, 106–16.CrossRefGoogle Scholar
Hein, J. R., Yeh, H.-W. & Alexander, E. 1979. Origin of iron-rich montmorillonite from the manganese nodule belt of the North Equatorial Pacific. Clays and Clay Minerals 27, 185–94.CrossRefGoogle Scholar
Jacobs, L., Emerson, S. & Huested, S. S. 1987. Trace metal geochemistry in the Cariaco Trench. Deep-Sea Research 34, 965–81.CrossRefGoogle Scholar
Jacobs, L., Emerson, S. & Skei, J. 1985. Partitioning and transport of metals across the 02/H2S interface in a permanently anoxic basin: Framvaren Fjord, Norway. Geochimica et Cosmochimica Acta 49, 1433–44.CrossRefGoogle Scholar
James, D. M. D. 1975. Caradoc turbidites at Poppit Sands (Pembrokeshire), Wales. Geological Magazine 112, 295–304.CrossRefGoogle Scholar
Kawahata, H., Fujioka, K. & Ishizuka, T. 1986. Sediments and interstitial water at sites 582 and 584, the Nankai Trough and the Japan Trench landward slope. Initial Reports of the Deep Sea Drilling Project 87, 865–75.Google Scholar
Krishnaswami, S. 1976. Authigenic transition elements in Pacific pelagic clays. Geochimica et Cosmochimica Acta 40, 425–34.CrossRefGoogle Scholar
McLennan, S. M., Taylor, S. R., McCulloch, M. T. & Maynard, J. B. 1990. Geochemical and Nd-Sr isotopic composition of deep-sea turbidites: Crustal evolution and plate tectonic associations. Geochimica et Cosmochimica Acta 54, 2015–50.CrossRefGoogle Scholar
Pratt, W. 1991. The Nod Glas decollement of the Welsh Basin. Geological Magazine 128, 279–82.CrossRefGoogle Scholar
Roberts, B., Morrison, C. & Hirons, S. 1990. Low grade metamorphism of the Manx Group, Isle of Man: a comparative study of white mica ‘crystallinity’ techniques. Journal of the Geological Society, London 147, 271–7.CrossRefGoogle Scholar
Sayles, F. L. 1979. The composition and diagenesis of interstitial solutions - I. Fluxes across the seawater-sediment interface in the Atlantic Ocean. Geochimica et Cosmochimica Acta 43, 527–45.CrossRefGoogle Scholar
Sayles, F. L. 1981. The composition and diagenesis of interstitial solutions - II. Fluxes and diagenesis at the water-sediment interface in the high latitude North and South Atlantic. Geochimica et Cosmochimica Acta 45, 1061–86.CrossRefGoogle Scholar
Sayles, F. L. & Manheim, F. T. 1975. Interstitial solutions and diagenesis in deeply buried marine sediments: results from the Deep Sea Drilling Project. Geochimica et Cosmochimica Acta 39, 103–27.CrossRefGoogle Scholar
Shaw, T. J., Gieskes, J. M. & Jahnke, R. A. 1990. Early diagenesis in differing environments: The response of transition metals in pore water. Geochimica et Cosmochimica Acta 54, 1233–46.CrossRefGoogle Scholar
Stoffyn-Egli, P. & Mackenzie, F. T. 1984. Mass balance of dissolved lithium in the oceans. Geochimica et Cosmochimica Acta 48, 859–72.CrossRefGoogle Scholar
Theng, B. K. G. 1974. The chemistry of clay-organic reactions. London: Adam Hilger, xii + 343 pp.Google Scholar
Thompson, M. & Walsh, J. N. 1988. The Handbook of Inductively Coupled Plasma Spectrometry, 2nd ed. Glasgow & London: Blackie, vi + 316 pp.Google Scholar
Thomson, J., Carpenter, M. S. N., Colley, S., Wilson, T. R. S., Elderfield, H. & Kennedy, H. 1984. Metal accumulation rates in northwest Atlantic pelagic sediments. Geochimica et Cosmochimica Acta 48, 1935–48.CrossRefGoogle Scholar