Hostname: page-component-78c5997874-xbtfd Total loading time: 0 Render date: 2024-11-19T09:36:18.459Z Has data issue: false hasContentIssue false
  • English
  • Français

Carboniferous dikes of West Connacht, Ireland

Published online by Cambridge University Press:  03 November 2011

J. G. Mitchell  and
P. Mohr
J. G. Mitchell
Affiliation:
School of Physics, The University, Newcastle-upon-Tyne NE1 7RU, England.
P. Mohr
Affiliation:
Department of Geology, University College Galway, Galway, Republic of Ireland.
Get access Rights & Permissions [Opens in a new window]

Abstract

Vigorous Carboniferous extensional tectonism and associated igneous activity is a feature of Ireland and the neighbouring areas of Newfoundland and Britain. In West Connacht, Ireland, dolerite dikes of late Carboniferous age are newly recognised and distinguished from Tertiary dolerites. In the N, the 320 Ma-old Logmor dike trends N–S across the Ordovician South Mayo Trough, and has an evolved, mildly alkaline basalt geochemistry. In the S, in Connemara, a diffuse and arcuate swarm of ENE–NE trending, 305 Ma-old dolerite dikes, the Teach Doite swarm, cuts the Galway Granite batholith and its envelope of Dalradian gneisses. These more tholeiitic dolerites reveal the mineralogical and geochemical effects of varying degrees of pervasive hydrothermal alteration, imposed on an original magmatic composition similar to that of mid-ocean ridge basalts. Variscan overprinting on k–Ar ages from West Connacht dolerites clusters at 300, 245 and 205 Ma. Overprinting is also a feature of much of the Galway Granite. Carboniferous diking in West Connacht may have responded to nascent opening of the proximate North Atlantic, its pattern related to domal uplift adjacent to the rifted zone.

Keywords

dike swarmGalway Granitegeochemistrypetrographyradiometric datesrare-earth elementstectonothermal eventsVariscan.
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 78 , Issue 3 , 1987 , pp. 133 - 151
Copyright
Copyright © Royal Society of Edinburgh 1987

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

Aucott, J. W. 1966. The petrology, structure and geochemistry of the Galway Granite in the Crook Moithan area, Connemara, Co. Galway, Eire. Unpublished Ph.D. Thesis, Bristol University.Google Scholar
Barberi, F., Ferrara, G., Santacroce, R., Treuil, M. & Varet, J. 1975. A transitional basalt-pantellerite sequence of fractional crystallisation: the Boina centre (Afar rift, Ethiopia). J PETROL 16, 22–56.CrossRefGoogle Scholar
Baxter, A. N. & Mitchell, J. G. 1984. Camptonite-monchiquite dyke swarms of northern Scotland; age relationships and their implications. SCOTT J GEOL 20, 297–308.CrossRefGoogle Scholar
Bott, M. H. P. 1982. Origin of the lithospheric tension causing basin formation. PHILOS TRANS R SOC LONDON A305, 319–24.Google Scholar
Brooks, C. K. 1976. The Fe2O3/FeO ratio of basalt analyses: an appeal for a standardised procedure. BULL GEOL SOC DENMARK 25, 117–20.CrossRefGoogle Scholar
Claxton, C. W. 1965. The petrology and geochemistry of the Galway Granite in the Screeb, Invermore, Rosmuc area, Connemara, Eire. Unpublished Ph.D. Thesis, Hull University.Google Scholar
Cole, G. A. J. & Crook, T. 1910. On rock specimens dredged from the floor of the Atlantic off the coast of Ireland, and their bearing on submarine geology. MEM GEOL SURV IRELAND.Google Scholar
Coller, D. W. 1984. Variscan structures in the Upper Palaeozoic rocks of west central Ireland. In Hutton, D. H. and Sanderson, D. J. (eds) Variscan Tectonics of the North Atlantic Region, pp. 185–94. GEOL SOC LONDON SPEC PUBL 14.CrossRefGoogle Scholar
Cox, K. G. & Hawkesworth, C. J. 1984. Relative contribution of crust and mantle to flood basalt magmatism, Mahabaleshwar area, Deccan Traps. PHILOS TRANS R SOC LONDON A310, 627–41.Google Scholar
Cruise, R. J. 1878. Explanatory memoir to accompany Sheets 66 and 67, illustrating part of the Counties of Sligo, Leitrim, Roscommon, and Mayo. Dublin: Geological Survey of Ireland.Google Scholar
Dallmeyer, R. D. 1982. 40Ar/39 Ar ages from the Narragansett Basin and southern Rhode Island basement terrane: their bearing on the extent and timing of Alleghenian tectonothermal events in New England. BULL GEOL SOC AM 93, 1118–30.2.0.CO;2>CrossRefGoogle Scholar
De Fino, M., LaVolpe, L. & Varet, J. 1973. Geology and petrology of Manda-Inakir range and Moussa Alii volcano, Central Eastern Afar (Ethiopia and T.F.A.I.). REV GEOGR PHYS GEOL DYNAM 15, 373–86.Google Scholar
Dewey, J. F. 1963. The stratigraphy of the Lower Palaeozoic rocks of central Murrisk, Co. Mayo, Eire, and the evolution of the South Mayo Trough. J GEOL SOC LONDON 119, 313–44.CrossRefGoogle Scholar
Dewey, J. F. & McKerrow, W. S. 1963. An outline of the geomorphology of Murrisk and north-west Galway. GEOL MAG 100, 260–75.CrossRefGoogle Scholar
Dostal, J. & Fratta, M. 1977. Trace element geochemistry of a Precambrian diabase dike from western Ontario. CAN J EARTH SCI 14, 2941–4.CrossRefGoogle Scholar
Evans, B. W. 1959. The geology of the Toombeola district, Connemam, Eire. Unpublished Ph.D. Thesis, Oxford University.Google Scholar
Feely, M. M. J. 1982. Geological, geochemical and geophysical studies on the Galway Granite in the Costelloe/Inveran sector, Western Ireland. Unpublished Ph.D. Thesis, Galway University College.Google Scholar
Feely, M. M. J. & Madden, J. 1986. A quantitative regional gamma-ray survey on the Main Galway Granite, western Ireland. In Andrew, C. J., Crowe, R. W. A., Finlay, S., Pennell, W. M. & Pyne, J. F. (eds) Geology and Genesis of Mineral Deposits in Ireland, pp. 195–199. IR ASSOC ECON GEOL.CrossRefGoogle Scholar
Fitch, F. J., Miller, J. A. & Williams, S. C. 1970. Isotopic ages of British Carboniferous rocks. CR 6 CONGR INT GEOL STRATIGR CARBONIFÈRE, SHEFFIELD 2, 771–89.Google Scholar
Francis, E. H. 1978. Igneous activity in a fractured craton: Carboniferous volcanism in northern Britain. In Bowes, D. R. & Leake, B. E. (eds) Crustal Evolution in Northwestern Britain and adjacent regions. GEOL J SPEC ISSUE 10, 279–96.Google Scholar
Francis, E. H. 1983. Carboniferous–Permian igneous rocks. In Craig, G. Y. (ed.) Geology of Scotland, pp. 297–324. Edinburgh: Scottish Academic Press.Google Scholar
Fratta, M. & Shaw, D. M. 1974. ‘Residence’ contamination of K, Rb, Li, and T1 in diabase dikes. CAN J EARTH SCI 11, 422–9.CrossRefGoogle Scholar
Fyffe, L. R. & Barr, S. M. 1986. Petrochemistry and tectonic significance of Carboniferous volcanic rocks in New Brunswick. CAN J EARTH SCI 23, 1243–56.CrossRefGoogle Scholar
Gardiner, C. I. & Reynolds, S. H. 1912. The Ordovician and Silurian rocks of the Kilbride Peninsula (Mayo). Q J GEOL SOC LONDON 68, 75–102.CrossRefGoogle Scholar
Gleadow, A. J. W. 1978. Fission-track evidence for the evolution of rifted continental margins. US GEOL SURV OPEN FILE REP 78–701, 146–48.Google Scholar
Graham, J. R., Leake, B. E. & Ryan, P. D. 1985. The geology of South Mayo. 1:63360 map. Glasgow: Geology Department, Glasgow University.Google Scholar
Halliday, A. N. 1977. Isotopic age studies of mineralisation in western Europe. Unpublished Ph.D. Thesis, University of Newcastle-upon-Tyne.Google Scholar
Halliday, A. N. & Mitchell, J. G. 1983. k–Ar ages of clay concentrates from Irish orebodies and their bearing on the timing of mineralisation. TRANS R SOC EDINBURGH EARTH SCI 74, 1–14.CrossRefGoogle Scholar
Harland, W. B., Cox, A. V., Llewellyn, P. G.. Pickton, C. A. G., Smith, A. G. & Walters, R. 1982. A geological timescale. Cambridge: Cambridge University Press.Google Scholar
Haszeldine, R. S. 1984. Carboniferous North Atlantic palaeogeography: stratigraphic evidence for rifting, not megashear or subduction. GEOL MAG 121, 443–63.CrossRefGoogle Scholar
Ineson, P. R. & Mitchell, J. G. 1979. k–Ar ages from the ore deposits and related rocks of the Isle of Man. GEOL MAG 116, 117–28.CrossRefGoogle Scholar
Kinahan, G. H., Symes, R. G., Warren, J. L., Wilkinson, S. B., Nolan, J., Leonard, J. 1874. Geological map, sheet 84 (1:63,360). Dublin: Geological Survey of Ireland.Google Scholar
Kinahan, G. H., Symes, R. G., Wilkinson, S. B., Nolan, J., Leonard, H., 1876. Memoir to accompany sheets 73, 74 (part), 83, 84 (Westport, Eriff Valley, Killary Harbour, West L. Mask). Dublin: Geological Survey of Ireland.Google Scholar
Larsen, L. M. & Watt, W. S. 1985. Episodic volcanism during break-up of the North Atlantic: evidence from the East Greenland plateau basalts. EARTH PLANET SCI LETT 73, 105–16.CrossRefGoogle Scholar
Lawrence, G. 1968. The geochemistry of the Galway Granite of Lettermullen, Co. Galway, Eire. Unpublished Ph.D. Thesis, Bristol University.Google Scholar
Leake, B. E. 1978. Granite emplacement: the granites of Ireland and their origin. In Bowes, D. R. & Leake, B. E. (eds) Crustal Evolution in Northwestern Britain and adjacent regions. GEOL. J. SPEC. ISSUE 10, 221–48.Google Scholar
Leake, B. E., Tanner, P. W. G. & Senior, A. 1981. Fold traces (F3 to F5) and regional metamorphism in the Dalradian rocks of Connemara. 1:63360 map. Glasgow: Geology Department, Glasgow University.Google Scholar
Leeder, M. R. 1982. Upper Palaeozoic basins of the British Isles—Caledonide inheritance versus Hercynian plate margin processes. J GEOL SOC LONDON 139, 479–91.CrossRefGoogle Scholar
Lorenz, V. & Nicholls, I. A. 1976. The Permo-Carboniferous basin and range province of Europe: an application of plate tectonics. In Falke, H. (ed.) The continental Permian in Central, West and South Europe, pp. 313–42. Dordrecht: Reidel.CrossRefGoogle Scholar
Macdonald, R., Gottfried, D., Farrington, M. J., Brown, F. W. & Skinner, N. G. 1981. Geochemistry of a continental tholeiite suite: late Palaeozoic quartz dolerite dykes of Scotland. TRANS R SOC EDINBURGH EARTH SCI 72, 57–74.CrossRefGoogle Scholar
Matthews, S. C. 1984. Northern margins of the Variscides in the North Atlantic region: comments on the tectonic context of the problem. In Hutton, D. H. & Sanderson, D. J. (eds) Variscan Tectonics of the North Atlantic Region. GEOL SOC LONDON SPEC PUBL 14, 71–85.Google Scholar
McKerrow, W. S. & Campbell, C. J. 1960. The stratigraphy and structure of the lower Palaeozoic rocks of north-west Galway. SCI PROC R DUBLIN SOC 1A, 27–52.Google Scholar
Mitchell, J. G. & Halliday, A. N. 1976. Extent of Triassic/Jurassic hydrothermal ore deposits on the North Atlantic margins. TRANS INST MIN METAL B85, 159–61.Google Scholar
Mitchell, J. G. & Mohr, P. 1986. k–Ar systematics in Tertiary dolerites from West Connacht, Ireland. SCOTT J GEOL 22, 225–240.CrossRefGoogle Scholar
Mohr, P. 1982. Tertiary dolerite intrusions of west-central Ireland. PROC IR ACAD 82B, 53–82.Google Scholar
Mohr, P. 1987. Crustal contamination in mafic sheets: a summary. GEOL ASSOC CAN SPEC PAPER 34 (in press).Google Scholar
Morrison, M. A., Hendry, G. L. & Leat, P. T. 1987. Regional and tectonic implications of parallel Caledonian and Permo-Carboniferous lamprophyre dyke swarms from Lismore, Ardgour. TRANS R SOC EDINBURGH: EARTH SCI 77 (for 1986), 279–288.CrossRefGoogle Scholar
Murthy, M. V. N. 1948. Camptonite dykes from Inishowen, County Donegal, Ireland. TRANS GEOL SOC GLASGOW 21, 205–6.Google Scholar
Neumann, E.-R., Larsen, B. T. & Sundvoll, B. 1985. Compositional variations among gabbroic intrusions in the Oslo rift. LITHOS 18, 35–59.Google Scholar
Nockolds, S. R., Knox, R. B. O'B., & Chinner, G. A. 1978. Petrology. London: Cambridge University Press.Google Scholar
Patchett, P. J. 1980. Thermal effects of basalt on continental crust and crustal contamination of magmas. NATURE 283, 559–61.CrossRefGoogle Scholar
Pearce, J. A. & Norry, M. J. 1979. Petrogenetic implications of Ti, Zr, Y and Nb variations in volcanic rocks. CONTRIB MINER PETROL 69, 33–47.CrossRefGoogle Scholar
Penn, I. E. et al. 1983. The Lame No. 2 borehole: discovery of a new Permian volcanic centre. SCOTT J GEOL 19, 333–46.CrossRefGoogle Scholar
Phillips, W. E. A. & Sevastopoulo, G. 1986. The stratigraphic and structural setting of Irish mineral deposits. In Andrew, C. J., Crowe, R. W. A., Finlay, S., Pennell, W. M. & Pyne, J. F. (eds) Geology and Genesis of Mineral Deposits in Ireland, 1–30. IR ASSOC ECON GEOL.CrossRefGoogle Scholar
Piccirillo, E. M., Justin-Visentin, E., Zanettin, B., Joron, J. L. & Treuil, M. 1979. Geodynamic evolution from plateau to rift: major and trace element geochemistry of the central eastern Ethiopian Plateau volcanics. N JB GEOL PALAONT ABH 158, 139–79.Google Scholar
Rast, N. 1984. The Alleghenian orogeny in eastern North America. In Hutton, D. H. & Sanderson, D. J. (eds) Variscan Tectonics of the North Atlantic Region. GEOL SOC LONDON SPEC PUBL 14, 197–217.CrossRefGoogle Scholar
Richey, J. E. 1939. The dykes of Scotland. TRANS EDINBURGH GEOL SOC 13, 393–435.CrossRefGoogle Scholar
Robinson, T. D. 1987. Connemara: 1:63360 map and guide. Folding Landscapes (in press).Google Scholar
Rock, N. M. S. 1983. The Permo-Carboniferous camptonitemonchiquite dyke-suite of the Scottish Highlands and Islands: distribution, field and petrological aspects. REP INST GEOL SCI GB 82/14.Google Scholar
Russell, M. J. 1972. North-South geofractures in Scotland and Ireland. SCOTT J GEOL 8, 73–84.CrossRefGoogle Scholar
Russell, M. J. & Smythe, D. K. 1978. Evidence for an early Permian oceanic rift in the northern North Atlantic. In Neumann, E.-R. & Ramberg, I. B. (eds) Petrology and geochemistry of continental rifts, pp. 173–9. Dordrecht: Reidel.CrossRefGoogle Scholar
Russell, M. J. & Smythe, D. K. 1983. Origin of the Oslo Graben in relation to the Hercynian-Alleghenian orogeny and lithospheric rifting in the North Atlantic. TECTONOPHYSICS 94, 457–72.CrossRefGoogle Scholar
Ryan, P. D. & Archer, J. B. 1977. The South Mayo Trough: a possible Ordovician Gulf of California-type marginal basin in the West of Ireland. CAN J EARTH SCI 14, 2453–61.CrossRefGoogle Scholar
Sanders, I. S. 1986. Gas filter-pressing origin for segregation vesicles in dykes. GEOL MAG 123, 67–72.CrossRefGoogle Scholar
Schilling, J.-G., Sigurdsson, H. & Kingsley, R. H. 1978. Skagi and Western neovolcanic zones in Iceland—2. geochemical variations. J GEOPHYS RES 83, 3983–4002.CrossRefGoogle Scholar
Senior, A. 1973. The geology of the Shannawona district, Connemara, Eire. Unpublished Ph.D. Thesis, Bristol University.Google Scholar
Smythe, D. K. et al. 1983. Major igneous episode of late Carboniferous-Permian age in northern Britain and the North Sea (Abstract). GEOL SOC LONDON NEWSLETTER 12, 37.Google Scholar
Stanton, W. I. 1953. The Lower Palaeozoic rocks of S.W. Murrisk, Eire. Unpublished Ph.D. Thesis, London University.Google Scholar
Stanton, W. I. 1960. The Lower Palaeozoic rocks of south-west Murrisk, Ireland. Q J GEOL SOC LONDON 116, 269–96.CrossRefGoogle Scholar
Strogen, P. 1977. The evolution of the Carboniferous volcanic complex of southeast Limerick, Ireland (abstract). J GEOL SOC LONDON 133, 409–10.Google Scholar
Strong, D. F., Dickson, W. L. & Pickerill, R. K. 1979. Chemistry and prehnite-pumpellyite facies metamorphism of calc-alkaline Carboniferous volcanic rocks of southeastern New Brunswick. CAN J EARTH SCI 16, 1071–85.CrossRefGoogle Scholar
Sutter, J. F. & Smith, T. E. 1979. 40Ar/39Ar analysis of diabase intrusions from Newark trend basins in Connecticut and Maryland: initiation of central Atlantic rifting. AM J SCI 279, 808–31.CrossRefGoogle Scholar
Thompson, P. 1985. Dating the British Tertiary Igneous Province in Ireland by the 40Ar/39Ar stepwise degassing method. Unpublished Ph.D. Thesis, Liverpool University.Google Scholar
Upton, B. G. J. 1982. Carboniferous to Permian volcanism in the stable foreland. In Sutherland, D. S. (ed.) Igneous Rocks of the British Isles, pp. 255–75. Chichester: John Wiley.Google Scholar
Watson, E. B. & Jurewicz, S. R. 1984. Behavior of alkalies during diffusive interaction of granitic xenoliths with basaltic magma. J GEOL 92, 121–31.CrossRefGoogle Scholar
Watson, J. 1985. Northern Scotland as an Atlantic-North Sea divide. J GEOL SOC LONDON 142, 221–43.CrossRefGoogle Scholar