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Stratigraphy in an accretionary prism: the Ordovician rocks in North Down, Ireland

Published online by Cambridge University Press:  03 November 2011

Lorraine E. Craig
Lorraine E. Craig
Affiliation:
Department of Geological Sciences, University of Birmingham, P.O. Box 363, Birmingham B15 2TT, England.
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Abstract

Sediments, mainly sandstones, conglomerates and shales, accumulated in small turbidite fans along the northern arc–trench margin of the Iapetus Ocean from middle Ordovician to Silurian time. These fans, together with the underlying pelagic facies and part of the oceanic crust, were sliced and accreted northward resulting in the Lower Palaeozoic accretionary prism which forms the Scottish Southern Uplands and the Longford-Down inlier in Ireland. North Down is the continuation of the Northern belt of the Southern Uplands of Scotland into Ireland, bounded to the S by the Orlock Bridge fault. Lithological and petrographical comparison with the rest of the Northern belt indicates closer affinities with the Southern Uplands of Scotland than with the western end of the Longford-Down inlier. Major ENE—WSW-trending Caledonian strike faults define five blocks, in which new formations of Caradoc and ? Ashgill age are defined. Pillowed spilitic rock, interpreted as a fragment of the ocean-floor, is only recognised in the Ballygrot block. Pelagic and hemipelagic black shales and cherts are overlain by arenaceous sediments in all blocks.

Keywords

black shaleCaradoccorrelationLongford-DownNorthern beltOrlock Bridge faultsandstone petrographySouthern Uplandsturbidite
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 74 , Issue 4 , 1984 , pp. 183 - 191
Copyright
Copyright © Royal Society of Edinburgh 1984

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References

Anderson, T. B. 1962. The stratigraphy, sedimentology and structure of the Silurian rocks of the Ards Peninsula, County Down. Unpublished Ph.D. Thesis, Liverpool University.Google Scholar
Clarke, R. 1902. Notes on the fossils of the Silurian area of North-east Ireland. GEOL MAG 9, 497–500.CrossRefGoogle Scholar
Craig, L. E. 1982. The Ordovician rocks of North Down. Unpublished Ph.D. Thesis, Queen's University, Belfast.Google Scholar
Craig, G. Y. & Walton, E. K. 1959. Sequence and structure in the Silurian rocks of Kirkcudbrightshire. GEOL MAG 96, 209–20.Google Scholar
Dewey, J. F. 1971. A model for the Lower Palaeozoic evolution of the southern margin of the early Caledonides of Scotland and Ireland. SCOTT J GEOL 7, 219–40.CrossRefGoogle Scholar
Floyd, J. D. 1975. The Ordovician rocks of West Nithsdale. Unpublished Ph.D. Thesis, St Andrews University.Google Scholar
Floyd, J. D. 1982. Stratigraphy of a flysch succession: the Ordovician of West Nithsdale, SW Scotland. TRANS R SOC EDINBURGH EARTH SCI 73, 1–9.Google Scholar
Hepworth, B. C., Oliver, G. J. H. & McMurtry, M. J. 1982. Sedimentology, volcanism, structure and metamorphism of the northern margin of a Lower Palaeozoic accretionary complex; Bail Hill-Abington area of the Southern Uplands of Scotland. In Leggett, J. K. (ed.) Trench—Forearc Geology: Sedimentation and Tectonics on Modern and Ancient Active Plate Margins, 521–36. SPEC PUBL GEOL SOC LONDON 10.Google Scholar
Hull, E., Warren, J. L. & Leonard, W. B. 1871. Explanatory Memoir to accompany Sheets 37, 39 and part of 29. MEM GEOL SURV IREL.Google Scholar
Kelling, G. 1961. The stratigraphy and structure of the Ordovician rocks of the Rhinns of Galloway. Q J GEOL SOC LONDON 117, 37–75.CrossRefGoogle Scholar
Kelling, G. 1962. The petrology and sedimentation of Upper Ordovician rocks in the Rhinns of Galloway. TRANS R SOC EDINBURGH 65, 107–37.CrossRefGoogle Scholar
Lamplugh, G. W., Kilroe, J. R., McHenry, A., Seymour, H. J., Wright, W. B. & Muff, H. B. 1904. The geology of the country around Belfast. MEM GEOL SURV IREL.Google Scholar
Lapworth, C. 1877. On the graptolites of County Down. REPPROC BELFAST NAT FIELD CLUB 1, 125–44.Google Scholar
Lapworth, C. 1889. On the Ballantrae rocks of south Scotland and their place in the Upland sequence. GEOL MAG 26, 20–24, 59–69.CrossRefGoogle Scholar
Leggett, J. K., McKerrow, W. S., Morris, J. H., Oliver, G. J. H. & Phillips, W. E. A. 1979. The north-western margin of the Iapetus Ocean. In Harris, A. L., Holland, C. H. & Leake, B. E. (eds) The Caledonides of the British Isles—reviewed, 263–67. SPEC PUBL GEOL SOC LONDON 8.Google Scholar
McKerrow, W. S., Leggett, J. K. & Eales, M. H. 1977. Imbricate thrust model of the Southern Uplands of Scotland. NATURE 267, 237–9.Google Scholar
Moore, G. F. & Karig, D. E. 1976. Development of sedimentary basins on the lower trench slope. GEOLOGY 4, 693–97.2.0.CO;2>CrossRefGoogle Scholar
Morris, J. H. 1979. The geology of the western end of the Lower Palaeozoic Longford-Down inlier, Ireland. Unpublished Ph.D. Thesis, Dublin University.Google Scholar
Peach, B. N. & Horne, J. 1899. The Silurian rocks of Britain 1, Scotland. MEM GEOL SURV U K.Google Scholar
Robbie, J. A. 1960. District reports—(C) Geological Survey of Northern Ireland. In SUMM PROG GEOL SURV G B for 1959, 44–5.Google Scholar
Robbie, J. A. 1961. District reports—(C) Geological Survey of Northern Ireland. In SUMM PROG GEOL SURV G B for 1960, 48–9.Google Scholar
Sanders, I. S. & Morris, J. H. 1978. Evidence for Caledonian subduction from greywacke detritus in the Longford-Down inlier. J EARTH SCI R DUBLIN SOC 1, 53–62.Google Scholar
Sharpe, E. N. 1970. An occurrence of pillow lavas in the Ordovician of County Down. IR NAT J 16, 299–301.Google Scholar
Silver, E. A. & Beutner, E. C. 1980. Mélanges. GEOLOGY 8, 32–4.2.0.CO;2>CrossRefGoogle Scholar
Swanston, W. 1877. On the Silurian rocks of County Down. REP PROC BELFAST NAT FIELD CLUB 1, 107–23.Google Scholar
Walton, E. K. 1955. Silurian greywackes in Peeblesshire. PROC R SOC EDINBURGH B65, 327–57.Google Scholar
Walton, E. K. 1965. Lower Palaeozoic rocks: stratigraphy palaeogeography and structure. In Craig, G. Y. (ed.) The Geology of Scotland, 161–227. Edinburgh: Oliver & Boyd.Google Scholar