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Combined Sm-Nd and Rb-Sr isotope systematics in the Donegal granitoids and their petrogenetic implications

Published online by Cambridge University Press:  01 May 2009

C. S. Dempsey ,
A. N. Halliday  and
I. G. Meighan
C. S. Dempsey
Affiliation:
Department of Geology, The Queen's University of Belfast, Belfast BT7 1NN, U.K.
A. N. Halliday
Affiliation:
Isotope Geology Unit, Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow G75 0QU, U.K.
I. G. Meighan
Affiliation:
Department of Geology, The Queen's University of Belfast, Belfast BT7 1NN, U.K.
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Abstract

The metaluminous to peraluminous granitoids of the Donegal batholith, northwest Ireland, were emplaced at c. 400 Ma into greenschist-amphibolite facies metasediments of the Dalradian Supergroup. Sm-Nd and Rb-Sr isotopic data are provided for eleven granitoid samples from six of the plutons and one specimen from the northeast granodiorite pluton of the Newry complex, Co. Down; the Donegal results reveal essentially similar initial Sr isotope ratios (0.7051–0.7068) but highly variable initial eNd values, −1.2 to −8.3 (and −0.5 for Newry). Certain granitoids have distinctive Nd isotopic compositions characteristic of the involvement of old, LREE-enriched continental crust in some cases or young crust and/or mantle-derived magmas in others. The Nd and Sr isotopic variations can be explained by a variety of mixing hypotheses.

Type
Articles
Information
Geological Magazine , Volume 127 , Issue 1 , January 1990 , pp. 75 - 80
Copyright
Copyright © Cambridge University Press 1990

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References

Bamford, D., Nunn, K., Prodehl, C. & Jacob, B. 1977. LISPB – III. Upper crustal structure of northern Britain. Journal of the Geological Society of London 133, 481–88.CrossRefGoogle Scholar
Bamford, D., Nunn, K., Prodehl, C. & Jacob, B. 1978. LISPB – IV. Crustal structure of northern Britain. Geo-physical Journal of the Royal Astronomical Society 54,43–60.CrossRefGoogle Scholar
Blaxland, A. B., Aftalion, M. & Van Breemen, O. 1979. Pb isotopic composition of feldspars from ScottishCaledonian granites, and the nature of the underlying crust. Scottish Journal of Geology 15, 139–51.CrossRefGoogle Scholar
DePaolo, D. J. 1981. A neodymium and strontium isotopic study of the Mesozoic calc-alkaline granitic batholiths of the Sierra Nevada and Peninsular Ranges California. Journal of Geophysical Research 86, 10470–88.CrossRefGoogle Scholar
Frost, C. D. & O'Nions, R. K. 1985. Caledonian magma genesis and crustal recycling. Journal of Petrology 26, 515–44.CrossRefGoogle Scholar
Halliday, A. N. 1984. Coupled Sm–Nd and U–Pb system-atics in late Caledonian granites and the basement under northern Britain. Nature 307, 229–33.CrossRefGoogle Scholar
Halliday, A. N., Aftalion, M. & Leake, B. E. 1980. A revised age for the Donegal granites. Nature 284, 542–3.CrossRefGoogle Scholar
Halliday, A. N., Aftalion, M., Van Breemen, O. & Jocelyn, J. 1979. Petrogenetic significance of Rb-Sr and U–Pb isotopic systems in the 400 Ma old British Isles granitoids and their hosts. In The Caledonides of the British Isles–Reviewed (ed. Harris, A. L., Holland, C. H. and Leake, B. E.), pp. 653–61. Special Publication of the Geological Society of London no. 8.Google Scholar
Halliday, A. N., Fallick, A. E., Dickin, A. P., Mac-kenzie, A. B., Stephens, W. E. & Hildreth, W. 1983. The isotopic and chemical evolution of Mount St. Helens. Earth and Planetary Science Letters 63, 241–56.CrossRefGoogle Scholar
Halliday, A. N., Fallick, A. E., Hutchinson, J. & Hildreth, W. 1984. A Nd, Sr and O isotopic investigation into the causes of chemical and isotopic zonation in the Bishop Tuff, California. Earth and Planetary Science Letters 68, 379–91.CrossRefGoogle Scholar
Halliday, A. N., Stephens, W. E., Hunter, R. H., Men-zies, M. A., Dickin, A. P. & Hamilton, P. J. 1985. Isotopic and chemical constraints on the building of the deep Scottish lithosphere. Scottish Journal of Geology 21, 465–91.CrossRefGoogle Scholar
Hamilton, P. J., Bluck, B. J. & Halliday, A. N. 1984. Sm–Nd ages from the Ballantrae complex, SW Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences 75, 183–7.CrossRefGoogle Scholar
Harmon, R. S. & Halliday, A. N. 1980. Oxygen and strontium isotope relationships in the British late Caledonian granites. Nature 283, 21–5.CrossRefGoogle Scholar
Harmon, R. S., Halliday, A. N., Clayburn, J. A. P. & Stephens, W. E. 1984. Chemical and isotopic systematics of the Caledonian intrusions of Scotland and Northern England: a guide to magma source region and magma-crust interaction. Philosophical Transactions of the Royal Society, of London A310, 709–42.Google Scholar
Hutton, D. H. W. 1982. A tectonic model for the emplacement of the Main Donegal Granite, NW Ireland. Journal of the Geological Society of London 139, 615–31.CrossRefGoogle Scholar
Liew, T. C. & McCulloch, M. T. 1985. Genesis of granitoid batholiths of Peninsular Malaysia and implications for models of crustal evolution: evidence from a Nd–Sr isotopic and U–Pb zircon study. Geochimica el Cosmochimica Acta 49, 587–600.CrossRefGoogle Scholar
McCulloch, M. T. & Chappell, B. W. 1982. Nd isotopic characteristics of S- and I-type granites. Earth and Planetary Science Letters 58, 51–64.CrossRefGoogle Scholar
MacIntyre, R. M. & van Breemen, O. 1975. Isotopic study of the gneiss complex, Inishtrahull, Co. Donegal. Scientific Proceedings of the Royal Dublin Society 5A, 301–9.Google Scholar
Meighan, I. G. & Neeson, J. C. 1979. The Newry Igneous Complex, County Down. In The Caledonides of the British Isles – Reviewed (ed. Harris, A. L., Holland, C. H. and Leake, B. E.), pp. 717–22. Special Publication of the Geological Society of London no. 8.Google Scholar
O'Connor, P. J., Long, C. B. & Evans, J. A. 1987. Rb-Sr whole-rock isochron studies of the Barnesmore and Fanad plutons, Donegal, Ireland. Geological Journal 22, 11–23.CrossRefGoogle Scholar
O'Connor, P. J., Long, C. B., Kennan, P. S., Halliday, A. N., Max, M. D. & Roddick, J. C. 1982. Rb-Sr isochron study of the Thorr and Main Donegal Granites, Ireland. Geological Journal 17, 279–95.CrossRefGoogle Scholar
Pidgeon, R. T. & Aftalion, M. 1978. Cogenetic and inherited zircon U-Pb systems in granites: Palaeozoic granites of Scotland and England. In Crustal Evolution in Northwestern Britain and Adjacent Regions (ed. Bowes, D. R. and Leake, B. E.), pp. 183–220. Special Issue of the Geological Journal no. 10.Google Scholar
Pitcher, W. S. & Read, H. H. 1959. The Main Donegal Granite. Quarterly Journal of the Geological Society of London 114, 259–305.CrossRefGoogle Scholar
Pitcher, W. S., Elwell, R. W. D., Tozer, C. F. & Cambray, F. W. 1964. The Leannan fault. Quarterly Journal of the Geological Society of London 120, 241–73.CrossRefGoogle Scholar
Pitcher, W. S. & Berger, A. R. 1972. The Geology of Donegal: A study of granite emplacement and unroofing. New York, London: Wiley. 435 pp.Google Scholar