Hostname: page-component-78c5997874-8bhkd Total loading time: 0 Render date: 2024-11-08T05:13:20.142Z Has data issue: false hasContentIssue false
  • English
  • Français

Silurian provenance variation in the Southern Uplands terrane, Scotland, assessed using neodymium isotopes and linked with regional tectonic evolution

Published online by Cambridge University Press:  03 November 2011

P. Stone  and
J. A. Evans
P. Stone
Affiliation:
P. Stone, British Geological Survey, Murchison House, West Mains Road, Edinburgh EH9 3LA,Scotland, U.K. e-mail: [email protected]
J. A. Evans
Affiliation:
J. A. Evans, Nerc Isotope Geosciences Laboratory, Keyworth, Nottingham NG12 5GG, England, U.K.
Get access Rights & Permissions [Opens in a new window]

Abstract

ABSTRACT

The progressive changes in the provenance of Silurian greywacke turbidites in the Southern Uplands terrane reflect geotectonic events at the Laurentian continental margin during closure of the Iapetus Ocean. In the northern Gala Group, juvenile andesitic detritus in some beds gives εNd values no lower than −4·2; more commonly, quartzo-feldspathic greywackes have εNd values in the −5·5 to −6·7 range, produced by the mixing of juvenile plutonic and Proterozoic basement detritus during arc unroofing. In the southern (younger) Gala Group, Proterozoic εNd values range down from −7·7 to −11·2 with only sporadic evidence for a juvenile component. An abrupt change is seen between the Gala Group and its tectonostratigraphical successor, the Hawick Group. In the latter, εNd values have a compact range between −4·7 and −6·6, indicating the renewed dominance of a more juvenile, plutonic provenance. Regional variations in the Sr/Rb ratio suggest that this was more evolved than the source of the Gala Group plutonic material. The Wenlock greywackes of the Riccarton Group have εNd values in the range −5·1 to −7·8, overlapping with the Hawick Group and with coeval greywackes from both the Midland Valley and Lakesman terranes. Overall, the data support proposals that the Iapetus Ocean had effectively closed by mid-Silurian times. Conversely, data from greywacke boulders in the basal Old Red Sandstone conglomerate of the Midland Valley terrane militate against its Wenlock juxtaposition with the Southern Uplands.

Keywords

Gala GroupgreywackeHawick GroupIapetus OceanLake DistrictMidland Valley
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. 447 - 455
Copyright
Copyright © Royal Society of Edinburgh 2000

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, M. W., Barker, A. J., Bennet, D. G. & Dallmeyer, R. D. 1992. A tectonic model for Scandian terrane accretion in the northern Scandinavian Caledonides. Journal of the Geological Society, London 149, 727–41.CrossRefGoogle Scholar
Armstrong, H. A., Owen, A. W., Scrutton, C. T., Clarkson, E. N. K. & Taylor, C. M. 1996. Evolution of the Northern Belt, Southern Uplands: implications for the Southern Uplands controversy. Journal of the Geological Society, London 153, 197–205.CrossRefGoogle Scholar
Bluck, B. J. 1983. Role of the Midland Valley of Scotland in the Caledonian orogeny. Transactions of the Royal Society of Edinburgh: Earth Sciences 74, 119–36.CrossRefGoogle Scholar
Bouch, J. E., Hole, M. J., Trewin, N. H. & Morton, A. 1995. Low temperature mobility of the rare-earth elements during sandstone diagenesis. Journal of the Geological Society, London 152, 895–8.CrossRefGoogle Scholar
British Geological Survey 1993. Regional geochemistry of southern Scotland and part of northern England. Keyworth, Nottingham: British Geological Survey.Google Scholar
Davies, G. R., Gledhill, A. & Hawksworth, C. J. 1985. Upper crustal recycling in southern Britain: evidence from neodymium and strontium isotopes. Earth and Planetary Science Letters 75, 1–12.CrossRefGoogle Scholar
Duller, P. R. & Floyd, J. D. 1995. Turbidite geochemistry and provenance studies in the Southern Uplands of Scotland. Geological Magazine 132, 557–69.CrossRefGoogle Scholar
Evans, J. A., Stone, P. & Floyd, J. D. 1991. Isotopic characteristics of Ordovician greywacke provenance in the Southern Uplands of Scotland. In Morton, A. C., Todd, S. P., Haughton, P. D. W. (eds) Developments in sedimentary provenance studies. Geological Society, London, Special Publication 57, 161–72.Google Scholar
Evans, J. A. & Zalasiewicz, J. 1996. U–Pb, Pb–Pb and Sm–Nd dating of authigenic monazite: implications for the diagenetic evolution of the Welsh Basin. Earth and Planetary Science Letters 144, 421–33.CrossRefGoogle Scholar
Harland, W. B., Armstrong, R. L., Cox, A. V., Craig, L. E., Smith, A. G. & Smith, D.G. 1990. A geologic time scale 1989. Cambridge University Press.Google Scholar
Jacobsen, S. B. & Wasserburg, G. J. 1980. Sm–Nd evolution of chondrites. Earth and Planetary Science Letters 50, 139–55.CrossRefGoogle Scholar
Kassi, A. M. & Weir, J. A. 1993. Depositional and geotectonic history of the Gala area, eastern Southern Uplands, Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences 84, 161–73.CrossRefGoogle Scholar
Kemp, A. E. S. 1991. Discussion on Silurian collision and sediment dispersal patterns in southern Britain. Geological Magazine 128, 673.CrossRefGoogle Scholar
Kneller, B. C. 1991. A foreland basin on the southern margin of Iapetus. Journal of the Geological Society, London 148, 207–10.CrossRefGoogle Scholar
Kneller, B. C., King, L. M. & Bell, A. M. 1993. Foreland basin development and tectonics on the northwest margin of eastern Avalonia. Geological Magazine 130, 691–7.CrossRefGoogle Scholar
Leggett, J. K. 1987. The Southern Uplands as an accretionary prism: the importance of analogues in reconstructing palaeogeography. Journal of the Geological Society, London 144, 737–52.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
Leggett, J. K., McKerrow, W. S. & Casey, D. M. 1982. The anatomy of a Lower Palaeozoic accretionary forearc: the Southern Uplands of Scotland. In Leggett, J.K. (ed.) Trench-Forearc Geology. Geological Society, London, Special Publication 10, 495–520.CrossRefGoogle Scholar
Lugmair, G. W. & Marti, K. 1978. Lunar initial 143Nd/144Nd: differential evolution of the lunar crust and mantle. Earth and Planetary Science Letters 39, 349–57.CrossRefGoogle Scholar
McCaffrey, W. D. 1994. Sm–Nd isotopic characteristics of sedimentary provenance: the Windermere Supergroup of NW England. Journal of the Geological Society, London 151, 1017–21.CrossRefGoogle Scholar
Miller, R. G. & O'Nions, R. K. 1984. The provenance and crustal residence ages of British sediments in relation to palaeogeographic reconstructions. Earth and Planetary Science Letters 68, 459–70.CrossRefGoogle Scholar
Molyneux, S. G. 1987. Probable early Wenlock acritarchs from the Linkim Beds of the Southern Uplands. Scottish Journal of Geology 23, 301–13.CrossRefGoogle Scholar
Morris, J. H. 1987. The Northern Belt of the Longford–Down inlier, Ireland and Southern Uplands, Scotland: an Ordovician backarc basin. Journal of the Geological Society, London 144, 773–86.CrossRefGoogle Scholar
Phillips, E. R., Smith, R. A. & Carroll, S. 1998. Strike-slip, terrane accretion and the pre-Carboniferous evolution of the Midland Valley of Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences 88 (for 1997), 209–24.CrossRefGoogle Scholar
Rollinson, H. 1993. Using geochemical data: evaluation, presentation, interpretation. Harlow: Longman.Google Scholar
Rushton, A. W. A., Stone, P. & Hughes, R. A. 1996. Biostratigraphical control of thrust models for the Southern Uplands of Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences 86 (for 1995), 137–52.CrossRefGoogle Scholar
Soper, N. J. & Woodcock, N. H. 1990. Silurian collision and sediment dispersal patterns in southern Britain. Geological Magazine 127, 527–42.CrossRefGoogle Scholar
Stone, P. 1995. Geology of the Rhins of Galloway district. Memoir of the British Geological Survey, Sheets 1 and 3 (Scotland). Keyworth, Nottingham: BGS.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
Stone, P., Green, P. M., Lintern, B. C., Simpson, P. R. & Plant, J. A. 1993. Regional geochemical variation across the Iapetus Suture Zone: tectonic implications. Scottish Journal of Geology 29, 113–21.CrossRefGoogle Scholar
Stone, P., Green, P. M. & Williams, T. M. 1997. Relationship of source and drainage geochemistry in the British paratectonic Caledonides: an exploratory regional assessment. Transactions of the Institution of Mining and Metallurgy 106, B79–B84.Google Scholar
Stone, P., Plant, J. A., Mendum, J. R. & Green, P. M. 1999. A regional geochemical assessment of some terrane relationships in the British Caledonides. Scottish Journal of Geology 35, 145–56.CrossRefGoogle Scholar
Stone, P. & Evans, J. A. 1995. Nd-isotope study of provenance patterns across the British sector of the Iapetus Suture. Geological Magazine 132, 571–80.CrossRefGoogle Scholar
Stone, P. & Evans, J. A. 1997. A comparison of the Skiddaw and Manx groups (English Lake District and Isle of Man) using neodymium isotopes. Proceedings of the Yorkshire Geological Society 51, 343–7.Google Scholar
Styles, M. T., Perez-Alvarez, M. & Floyd, J. D. 1995. Pyroxenous greywackes in the Southern Uplands of Scotland and their petrotectonic implications. Geological Magazine 132, 539–47.CrossRefGoogle Scholar
Syba, E. 1989. The sedimentation and provenance of the Lower Old Red Sandstone Greywacke Conglomerate, southern Midland Valley, Scotland (Unpublished Ph.D. Thesis, University of Glasgow).Google Scholar
Thorogood, E. J. 1990. Provenance of pre-Devonian sediments of England and Wales: Sm–Nd isotopic evidence. Journal of the Geological Society, London 147, 591–4.CrossRefGoogle Scholar
Walton, E. K. & Oliver, G. J. H. 1991. Lower Palaeozoic—Stratigraphy. In Craig, G. Y. (ed.) Geology of Scotland (3rd edn). London: The Geological Society.Google Scholar
Wasserburg, G. L., Jacobsen, S. B., DePaolo, D. J., McCulloch, M. T. & Wen, T. 1981. Precise determination of Sm/Nd ratios, Sm and Nd isotopic abundances in standard solutions. Geochimica et Cosmochimica Acta 45, 2311–22.CrossRefGoogle Scholar
White, D. E., Barron, H. F., Barnes, R. P. & Lintern, B. C. 1991. Biostratigraphy of late Llandovery (Telychian) and Wenlock turbiditic sequences in the SW Southern Uplands, Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences 82, 297–322.CrossRefGoogle Scholar
Williams, T. M., Henney, P. J., Stone, P. & Lintern, B. C. 1996. Rare earth element geochemistry of Lower Palaeozoic turbidites in the British trans-Iapetus zone: provenance patterns and basin evolution. Scottish Journal of Geology 32, 1–8.CrossRefGoogle Scholar