Hostname: page-component-586b7cd67f-t7czq Total loading time: 0 Render date: 2024-11-26T06:20:00.276Z Has data issue: false hasContentIssue false
  • English
  • Français

Tschermak substitution as an indicator of palaeotemperature in Silurian K-bentonites from the Southern Uplands of Scotland and Northern Ireland

Published online by Cambridge University Press:  09 July 2018

R. B. Pearce  and
T. Clayton
R. B. Pearce
Affiliation:
Department of Geology, University of Southampton, Highfield, Southampton SO 171BJ, UK
T. Clayton
Affiliation:
Department of Geology, University of Southampton, Highfield, Southampton SO 171BJ, UK
Get access Rights & Permissions [Opens in a new window]

Abstract

Chemical analyses of the <0.2 μm illite-smectite (I-S) fraction from K-bentonites in Silurian age sediments sampled from three different localities in the Southern Uplands of Scotland and Northern Ireland indicate that the I-S from the three localities shows differences in both K+ content and the degree of Tschermak substitution of octahedral Al3+ for Mg2+. The K+ content correlates with percentage expandability (%E) of I-S as determined by X-ray diffraction (XRD), but both these parameters show poor correlation with palaeotemperature as estimated by organic reflectance methods. Octahedral Mg2+ content shows an inverse correlation with Al3+, and both these parameters show a good correlation with estimated palaeotemperature. Although K-substitution has been retarded at Dob's Linn, the region subjected to the highest temperature, Tschermak substitution of Al3+ for Mg2+ has apparently continued. In these K-bentonites, Tschermak substitution appears to be a better indicator of palaeotemperature than K-substitution.

Type
Research Article
Information
Clay Minerals , Volume 30 , Issue 1 , March 1995 , pp. 15 - 25
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1995

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

Anderson, T.B. & Cameron, T.D.J (1979) A structural profile of Caledonian deformation in Down. Pp. 263–267 in: The Caledonides of the British Isles-Reviewed (Harris, A.L., Holland, C.H. & Leake, B.E., editors). Geol. Soc. London, Spec. Publ. No. 8.Google Scholar
Awwiller, D.N. (1993) Illite/smectite formation and potassium mass transfer during burial diagenesis of mudrocks: a study from the Texas Gulf Coast Paleocene-Eocene. J. Sed. Pet. 63, 501–512.Google Scholar
Barker, C.E. & Pawlewlcz, M.J. (1986) The correlation of vitrinite reflectance with maximum temperature in humic organic matter. Pp. 79—93 in: Lecture Notes in Earth Sciences 5. Palaeogeothermics (Bunte-barth, G. & Stegena, L., editors). Springer-Verlag, Berlin.Google Scholar
Batchelor, R.A. & Weir, J.A. (1988) Metabentonite geochemistry: magmatic cycles and graptolite extinctions at Dob's Linn, southern Scotland. Trans. R. Soc. Edinb. 79, 19–41.Google Scholar
Bethke, C.M. & Altaner, S.P. (1986) Layer-by-layer mechanism of smectite illitization and application to a new rate law. Clays Clay Miner. 34, 136—145.CrossRefGoogle Scholar
Craig, G.Y. (1991) The Geology of Scotland. The Geological Society, London (3rd edition), 612p.Google Scholar
Eberl, D.D. & Hower, J. (1976) Kinetics of illite formation. Geol. Soc. Am. Bull. 87, 1326–1330.2.0.CO;2>CrossRefGoogle Scholar
Eberl, D.D. & środoń, J. (1988) Ostwald ripening and interparticle-diffraction effects for illite crystals. Am. Miner. 73, 1335–1345.Google Scholar
Eberl, D.D., środoń, J., Lee, M., Nadeau, P.H. & Northrop, H.R. (1987) Sericite from the Silverton Caldera, Colorado: Correlation among structure, composition, origin and particle thickness. Am. Miner. 72, 914–934.Google Scholar
Grim, R.E. & Güven, N. (1978) Bentonites, Geology, Mineralogy, Properties and Uses. Developments in Sedimentology 24. Elsevier, Amsterdam, 256p.Google Scholar
Hein, J.R. & Scholl, D.W. (1978) Diagenesis and distribution of late Cenozoic volcanic sediment in the southern Bering Sea. Geol. Soc. Am. Bull. 89, 197–210.2.0.CO;2>CrossRefGoogle Scholar
Hoffman, J. & Hower, J. (1979) Clay mineral assemblages as low grade metamorphic geothermometers: application to the thrust faulted disturbed belt of Montana, U.S.A. Pp. 55—79 in. Aspects of Diagenesis (Scholle, P.A. & Schluger, P.R., editors). Soc. Econ. Pal. Miner. Spec. Pub., 26.Google Scholar
Hower, J., Eslinger, E.V., Hower, M.E. & Perry, E.A. (1976) Mechanism of burial metamorphism of argillaceous sediment: 1. Mineralogical and chemi-cal evidence. Geol. Soc. Am. Bull. 87, 725–737.2.0.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. J. Geol. Soc. London 148, 861–868.CrossRefGoogle Scholar
Inoue, A., Minato, H. & Utada, M. (1978) Mineralogical properties and occurrence of illite/montmorillonite mixed layer minerals formed from Miocene volcanic glass in Waga-Omono district. Clay Sci. 5, 123–126.Google Scholar
Jiang, W.Z. & Peacor, D.R., Merriman, R.J. & Roberts, B. (1990) Transmission and analytical electron microscopic study of mixed-layer illite/smectite formed as an apparent replacement product of diagenetic illite. Clays Clay Miner. 38, 449–468.CrossRefGoogle Scholar
Kemp, A.E.S (1986) Tectonostratigraphy of the Southern Belt of the Southern Uplands. Scot. J. Geol. 22, 241–256.CrossRefGoogle Scholar
Kemp, A.E.S, Oliver, G.J.H & Baldwin, J.R. (1985) Low-grade metamorphism and accretion tectonics: Southern Uplands terrain, Scotland. Mineral. Mag. 49, 335–344.CrossRefGoogle Scholar
Klsch, H.J. (1987) Correlation between indicators of very low-grade metamorphism. Pp. 227—300 in: Low Temperature Metamorphism (Frey, M., editor). Blackie, Chapman & Hall, New York.Google Scholar
Leggett, J.K., Mckerrow, W.S. & Eales, M.H. (1979) The Southern Uplands of Scotland; a Lower Palaeozoic accretionary prism. J. Geol. London 136, 755–770.Google Scholar
Lumsden, G.I., Tulloch, W., Howells, M.F. & Davies, A. (1967) The geology of the neighbourhood of Langholm. Memoir Geol. Surv. Scot., Sheet 11, Edinburgh. HMSO.Google Scholar
Merriman, R.J. & Roberts, B. (1990) Metabentonites in the Moffat Shale Group, Southern Uplands of Scotland: Geochemical evidence of ensialic marginal basin volcanism. Geol. Mag. 127, 259–271.CrossRefGoogle Scholar
Merriman, R.J., Fortey, N.J. & Roberts, B. (1991) An excursion guide to areas of very low grade metamorphism in the Lake District and the Rhinns of Galloway. Brit. Geol. Surv. Technical Report WG/ 91/8.Google Scholar
Meunier, A. & Velde, B. (1989) Solid solutions in I/S mixed-layer minerals and illite. Am. Miner. 74, 1106–1112.Google Scholar
Miyashiro, A. & Akido, F. (1985). Tschermak substitution in low- and middle-grade pelitic schists. J. Pet. 26, 449–487.CrossRefGoogle Scholar
Ollver, G.J.H & Leggetr, J.K. (1980) Metamorphism in an accretionary prism: prehnite-pumpellyite facies metamorphism of the Southern Uplands of Scotland. Trans. R. Soc. Edinb. 71, 235–246.Google Scholar
Oliver, G.J.H, Smellie, J.L., Thomas, L.J., Casey, D.M., Kemp, A.E.S, Evans, L.J., Baldwin, J.R. & Hepworth, B.C. (1984) Early Palaeozoic metamorphic history of the Midland Valley, Southern Uplands-Longford-Down Massif and the Lake District, British Isles. Trans. R. Soc. Edinb. 75, 245–258.CrossRefGoogle Scholar
Pearce, R.B. (1992) Clay-mineral transformations in Silurian sediments .from the Southern Uplands of Scotland and north-west England. PhD thesis, Univ. Southampton, UK.Google Scholar
Pearce, R.B. (1995) The geochemistry of Llandovery and Wenlock age K-bentonites in the Southern Uplands. Scot. J. Geol. 31 (in press).CrossRefGoogle Scholar
Pearce, R.B., Clayton, T. & Kemp, A.E.S (1991) Illitization and organic maturity in Silurian sediments from the Southern Uplands of Scotland. Clay Miner. 26, 199–210.CrossRefGoogle Scholar
Reynolds, JR.R.C. (1985) NEWMOD - A Computer Program for the Calculation of the One-Dimensional Patterns of Mixed-Layered Clays. Reynolds, R.C., 8 Brook Rd., Hanover, New Hampshire.Google Scholar
Smart, G. & Clayton, T. (1985) The progressive illitization of interstratified illite-smectite from Carboniferous sediments of northern England and its relationship to organic maturity indicators. Clay Miner. 20, 455–466.CrossRefGoogle Scholar
Środoń, J. (1984) X-ray powder diffraction identification of illitic clay materials. Clays Clay Miner. 32, 337–349.CrossRefGoogle Scholar
Tricker, P.M., Marshall, J.E.A & Badman, T.D. (1992) Chitinozoan reflectance: a Lower Palaeozoic thermal maturity indicator. Mar. Petrol. Geology 9, 302–307.CrossRefGoogle Scholar
Watson, S.W. (1976) The sedimentary geochemistry of the Moffat Shales - a carbonaceous sequence in the Southern Uplands of Scotland. PhD thesis, Univ. St. Andrews, UK.Google Scholar
Weaver, C.E. (1989) Clays, Muds and Shales. Developments in Sedimentology 44. Elsevier, Amsterdam, 819p.Google Scholar
Weaver, C.E. & Pollard, L.D. (1973) The Chemistry of Clay Minerals. Elsevier, Amsterdam, 213p.Google Scholar
Wolf, M. (1975) Über die Beziehungen zwischen Illit-Kristallinitäit und Inkohlung. (On the relations between illite crystallinity and coalification). 19. Jb. geol. Palaeont. 7, 437–447.Google Scholar