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Scottish Silurian shorelines

Published online by Cambridge University Press:  03 November 2011

Euan N. K. Clarkson ,
David A. T. Harper  and
Cecilia M. Taylor
Euan N. K. Clarkson
Affiliation:
Euan N. K. Clarkson and Cecilia M. Taylor, Department of Geology and Geophysics, University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh EH9 3JW, Scotland, U.K.
David A. T. Harper
Affiliation:
David. A. T. Harper, Geologisk Museum, Oester Voldgade 5-7, 1350 Koebenhavn, Denmark.
Cecilia M. Taylor
Affiliation:
Euan N. K. Clarkson and Cecilia M. Taylor, Department of Geology and Geophysics, University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh EH9 3JW, Scotland, U.K.
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Abstract

ABSTRACT

The Silurian inliers of the Midland Valley of Scotland all exhibit a regressive sequence, and despite evident facies differences between inliers, marine successions invariably pass upwards into redbeds of continental origin. Contrasting types of shoreline facies can be seen in different inliers; here the beds in the North Esk Inlier (NEI) are compared with those previously described from Knockgardner. At Knockgardner a high energy coastal environment prevailed, but in the NEI very different conditions can be identified in near-contemporaneous deposits. In the NEI thin sandstones and siltstones of the Reservoir and Deerhope formations are succeeded by the sandstones and conglomeratic beds of the Cock Rig Formation. These are overlain by the marine mudstones of the Wether Law Linn Formation and, at the top of the sequence, the continental redbeds of the Henshaw Formation.

The Wether Law Linn Formation is interpreted, on various lines of evidence, as a lagoonal system. Conditions therein were initially fully marine, though within the photic zone, but subsequently the faunas were increasingly influenced by fluctuating salinity, prior to deposition of the redbeds. Such a lagoon would have required an offshore bar impounding it, which is represented by the Cock Rig Formation. These sedimentary rocks, previously interpreted as deposits of a laterally unconfined submarine channel, are now considered to be of shallow water origin. The succession closely conforms to classic models in which shoreface sands, consisting of small cross-bedded packets, are succeeded by tabular sandstone sheets representing foreshore beach deposits. Coarser and thicker beds, with herringbone cross-sets, linguoid ripples and trains of rounded pebbles, are interpreted as the deposits of tidal channels within the barrier complex. The barrier-lagoon system persisted throughout the whole of Cock Rig time and most or all of the time during which the Wether Law Linn Formation was deposited, and was either static or prograded seawards until the lagoon dried up during a final marine regression. The sedimentary and faunal evidence is consistent with this interpretation, and the contrast between the shoreline environments of the NEI and Knockgardner is striking. Brief reference is made to other inliers in the Midland Valley.

Keywords

Knockgardnerlagoonmarine regressionNorth Esk Inlieroffshore bar
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. 479 - 487
Copyright
Copyright © Royal Society of Edinburgh 2000

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References

Barnes, R. S. K. 1980. Coastal Lagoons, Cambridge Studies in Modern Biology 1. Cambridge University Press.Google Scholar
Batchelor, R. A. 1999. Metabentonites from the Silurian inliers of the southern Midland Valley of Scotland: distribution and geochemistry. Scottish Journal of Geology 35, 71–7.CrossRefGoogle Scholar
Batchelor, R. A. & Clarkson, E. N. K. 1993. Geochemistry of a Silurian metabentonite and associated apatite from the North Esk Inlier, Pentland Hills. Scottish Journal of Geology 29, 123–30.CrossRefGoogle Scholar
Bull, E. E. & Loydell, D. K. 1995. Uppermost Telychian graptolites from the North Esk Inlier, Pentland Hills, near Edinburgh. Scottish Journal of Geology 31, 163–70.CrossRefGoogle Scholar
Clarkson, E. N. K., Harper, D. A. T & Höey, A. N. 1998. Basal Wen-lock biofacies from the Girvan District, SW Scotland. Scottish Journal of Geology 34, 61–71.CrossRefGoogle Scholar
Clarkson, E. N. K. & Taylor, C. M. 1989. The Deerhope Coral Bed, a unique horizon in the Silurian of the Pentland Hills, near Edinburgh. Abstracts, Murchison Symposium, University of Keele, 37–8. Keele, Staffordshire: University of Keele.Google Scholar
Clifton, H. E., Hunter, R. E. & Phillips, R. L. 1971. Depositional structures and processes in the non-barred high-energy nearshore. Journal of Sedimentary Petrology 41, 651–70.Google Scholar
Davis, R. A. (ed.) 1978. Coastal sedimentary environments. New York: Springer.CrossRefGoogle Scholar
Elliott, T. 1986. Siliclastic shorelines. In Sedimentary Environments and Facies (2nd edn), pp. 155–88. Oxford: Blackwell Scientific Publications.Google Scholar
Harper, D. A. T., Scrutton, C. T. & Williams, D. M. 1995. Mass mortalities on an Irish sea floor. Journal of the Geological Society, London 152, 917–22.CrossRefGoogle Scholar
Kraft, J. C., Chrzastowski, M. J., Belknap, D. F., Toscano, M. & Fletcher, C. H. 1987. The transgressive barrier-lagoon coast of Delaware; morphostratigraphy, sedimentary sequences and responses to relative rise in sea level. In Nummedal, D. et al. (eds) Sea-level fluctuation and coastal evolution, S. E. P. M. Special Publication 41, 129–43. Tulsa, Oklahoma: S.E.P.M.CrossRefGoogle Scholar
Lovelock, C. E. 1998. The sedimentary environments and biofacies of the Silurian inlier at Lesmahagow, Midland Valley of Scotland (Unpublished Ph.D. Thesis, University of Edinburgh).Google Scholar
McGiven, A. 1967. Sedimentation and provenance of post-Valentian conglomerates up to and including the basal conglomerate of the Lower Old Red sandstone in the southern part of the Midland Valley of Scotland (Unpublished Ph. D. Thesis, University of Glasgow).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. Geological Magazine 127, 259–71.CrossRefGoogle Scholar
O'Connor, P. D. & Williams, D. M. 1999. Tectonic control on sedimentation during transgression: a case study from Silurian successions in Ireland and Scotland. Geological Magazine 136, 75–82.CrossRefGoogle Scholar
Paterson, I. D., McAdam, A. D. & MacPherson, K. A. T. 1998. Geology of the Hamilton District. Memoir of the British Geological Survey. Sheet 23W (Scotland), 1–94. London: The Stationery Office.Google Scholar
Peach, B. N. & Home, J. 1899. The Silurian Rocks of Britain, Volume 1. Scotland. Memoirs of the Geological Survey of the United Kingdom. Glasgow: HMSO.Google Scholar
Phillips, E. R., Smith, A. 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 89, 209–204.Google Scholar
Robertson, G. 1985. Palaeoenvironmental interpretation of the Silurian rocks of the Pentland Hills (Unpublished Ph. D. Thesis, University of Edinburgh).Google Scholar
Robertson, G. 1989. A palaeoenvironmental interpretation of the Silurian rocks in the Pentland Hills, near Edinburgh. Transactions of the Royal Society of Edinburgh: Earth Sciences 80, 127–42.CrossRefGoogle Scholar
Robertson, G. 1999. Upper Llandovery associations in the Pentland Hills, Scotland. In Boucot, A. J. & Lawson, J. D.Paleocom-munities—a case study from the Silurian and Lower Devonian, World Regional Geology Series 11, pp. 408–18. Cambridge University Press.Google Scholar
Rolfe, W. D. I. 1960. The Silurian Inlier of Carmichael, Lanarkshire. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 64, 245–60.CrossRefGoogle Scholar
Rolfe, W. D. I. 1961. The geology of the Hagshaw Hills Silurian inlier, Lanarkshire. Transactions of the Edinburgh Geological Society 18, 240–69.CrossRefGoogle Scholar
Siveter, D. J., Owens, R. M. & Thomas, A. T. 1989. Silurian field excursions; a geotraverse across Wales and the Welsh Borderland, National Museum of Wales, Geological Series 10, 1–133.Google Scholar
Smith, R. A. 1995. The Siluro-Devonian evolution of the southern Midland Valley of Scotland. Geological Magazine 132, 503–13.CrossRefGoogle Scholar
Tipper, J. C. 1974. Lower Silurian animal communities—three case histories. Lethaia 8, 15–25.Google Scholar
Tipper, J. C. 1976. The stratigraphy of the North Esk Inlier, Midlothian, Scotland. Scottish Journal of Geology 12, 15–25.CrossRefGoogle Scholar
Williams, D. M. & Harper, D. A. T. 1988. A basin model for the Silurian of the Midland Valley of Scotland. Journal of the Geological Society, London 145, 741–8.CrossRefGoogle Scholar
Williams, D. M. & Harper, D. A. T. 1991. End-Silurian modifications of Ordovician terranes in western Ireland. Journal of the Geological Society, London 149, 165–71.CrossRefGoogle Scholar
Ziegler, A. M., Cocks, L. R. M. & Bambach, R. K. 1968. The composition and structure of Lower Silurian marine communities. Lethaia 1, 1–27.CrossRefGoogle Scholar