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Anorogenic granite magma genesis: new isotopic data for the southern sector of the British Tertiary Igneous Province

Published online by Cambridge University Press:  03 November 2011

I. G. Meighan ,
A. E. Fallick  and
A. G. McCormick
I. G. Meighan
Affiliation:
I. G. Meighan and A. G. McCormick, Department of Geology, School of Geosciences,The Queen's University of Belfast, Belfast BT7 INN, Northern Ireland
A. E. Fallick
Affiliation:
A. E. Fallick, Isotope Geology Unit, Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow G75 0QU, Scotland
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Abstract

It is now generally accepted that British Tertiary granites contain crustal and mantle components. Genesis principally by differentiation of crustally contaminated basaltic magmas is widely held and silicic melts with some remarkable trace element similarities were generated within different upper crust along the St Kilda/Skye - Carlingford zone.

New whole-rock (and mineral) O isotope data for the southern sector of the province (N Arran, Ailsa Craig, Mourne Mountains, Slieve Gullion, etc) reveal that δ18O lies in the range +5·1 to +9·7‰ for most of the analysed granites, meteoric water-rock interaction having been in general less intensive than at Skye and Mull. Nevertheless, highly 18O-depleted country rocks (with δ18O<0) exist adjacent to the N Arran and Mourne Mountains granite plutons. There is as yet no evidence for the existence of low -18O granitic melts in this southern sector where magmatic δ18O compositions (up to c. + 9·5‰) can be inferred for some of the intrusions.

New Nd (and Sr) isotope data indicate that although there is some similarity in initial 87Sr/86Sr ratios between the northern and southern sector granites, in northeastern Ireland initial εNd values for the analysed Tertiary acid major intrusions range from −3·9 to −4·5. This is in marked contrast to the Skye granites, some of which have values below −20, reflecting the involvement of different lithosphere.

Keywords

ArranMourne MountainsAilsa Craig plutonsA-typesbasaltic differentiationcrustal contaminationmeteoric water-rock interactionSr, Nd, O isotopestrace elements
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 83 , Issue 1-2: Second Hutton Symposium: The Origin of Granites and Related Rocks , 1992 , pp. 227 - 233
Copyright
Copyright © Royal Society of Edinburgh 1992

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References

Bell, B. R. & Emeleus, C. H. 1988. A review of silicic pyroclastic rocks of the British Tertiary Volcanic Province. In Morton, A. C. & Parson, L. M. (eds) Early Tertiary Volcanism and the Opening of the NE Atlantic, 365–79. SPEC PUBL GEOL SOC LONDON 39.CrossRefGoogle Scholar
Bott, M. H. P. & Tuson, J. 1973. Deep Structure beneath the Tertiary Volcanic Regions of Skye, Mull and Ardnamurchan, North-west Scotland. NATURE PHYS SCI 242, 114–6.CrossRefGoogle Scholar
Brown, P. E. & Rushton, B. J. 1960. Some chemical data on the Mourne Mountain granite G2. GEOCHIM COSMOCHIM ACTA 18, 193–9.CrossRefGoogle Scholar
Chappell, B. W., White, A. J. R. & Wyborn, D. 1987. The Importance of Residual Source Material (Restite) in Granite Petrogenesis. J PETROL 28, 1111–38.CrossRefGoogle Scholar
Dickin, A. P. & Exley, R. A. 1981. Isotopic and Geochemical Evidence for Magma Mixing in the Petrogenesis of the Coire Uaigneich Granophyre, Isle of Skye N. W. Scotland. CONTRIB MINERAL PETROL 76, 98–108.CrossRefGoogle Scholar
Dickin, A. P., Moorbath, S. & Welke, H. J. 1981. Isotope, trace element and major element geochemistry of Tertiary igneous rocks, Isle of Arran, Scotland. TRANS R SOC EDINBURGH EARTH SCI 72, 159–70.CrossRefGoogle Scholar
Dickin, A. P., Brown, J. L., Thompson, R. N., Halliday, A. N. & Morrison, M. A. 1984. Crustal contamination and the granite problem in the British Tertiary Volcanic Province. PHILOS TRANS R SOC LONDON 310A, 755-80.Google Scholar
Dickin, A. P., Jones, N. W., Thirlwall, M. F. & Thompson, R. N. 1987. A Ce/Nd isotope study of crustal contamination processes affecting Palaeocene magmas in Skye, Northwest Scotland. CONTRIB MINERAL PETROL 96, 455–64.CrossRefGoogle Scholar
Eby, G. N. 1990. The A-type granitoids: A review of their occurrence and chemical characteristics and speculations on their petrogenesis. LITHOS 26, 115–34.CrossRefGoogle Scholar
Ferry, J. M. 1985. Hydrothermal alteration of Tertiary igneous rocks from the Isle of Skye, northwest Scotland II. Granites. CONTRIB MINERAL PETROL 91, 283–304.CrossRefGoogle Scholar
Forester, R. W. & Taylor, H. P. Jr, 1977. 18O/16O, D/H and 13C/12C studies of the Tertiary igneous complex of Skye, Scotland. AM J SCI 277, 136–77.CrossRefGoogle Scholar
Gamble, J. A., Meighan, I. G. & McCormick, A. G. 1992. The petrogenesis of Tertiary microgranites and granophyres from the Slieve Gullion Central Complex, NE Ireland. J GEOL SOC LONDON, 149, 93–106.CrossRefGoogle Scholar
Harding, R. R., Merriman, R. J. & Nancarrow, P. H. A. 1984. St Kilda: an illustrated account of the geology. REP BR GEOL SURV 16(7).Google Scholar
Harrison, R. K., Stone, P., Cameron, I. B., Elliot, R. W. & Harding, R. R. 1987. Geology, petrology and geochemistry of Ailsa Craig, Ayrshire. REP BR GEOL SURV 16(9).Google Scholar
Lyle, P. 1985. The petrogenesis of the Tertiary basaltic and intermediate lavas of northeast Ireland. SCOTT J GEOL 21, 71–84.CrossRefGoogle Scholar
McCormick, A. G., Fallick, A. E., Harmon, R. S., Meighan, I. G. & Gibson, D. (under review). Oxygen and hydrogen isotope geochemistry of the Mourne Mountains Tertiary granites, Northern Ireland. J PETROL (under review).Google Scholar
Macdonald, R., Sparks, R. S. J., Sigurdsson, H., Mattey, D. P., McGarvie, D. W. & Smith, R. L. 1987. The 1875 eruption of Askja volcano, Iceland: combined fractional crystallization and selective contamination in the generation of rhyolitic magma. MINERAL MAG 51, 183–202.CrossRefGoogle Scholar
Macdonald, R., McGarvie, D. W., Pinkerton, H., Smith, R. L. & Palacz, Z. A. 1990. Petrogenetic Evolution of the Torfajökull Volcanic Complex, Iceland I. Relationship Between the Magma Types. J PETROL 31, 429–59.CrossRefGoogle Scholar
Marshall, L. A. & Sparks, R. S. J. 1984. Origin of some mixed-magma and net-veined ring intrusions. J GEOL SOC LONDON 141, 171–82.CrossRefGoogle Scholar
Meighan, I. G. 1979. The acid igneous rocks of the British Tertiary Province. BULL GEOL SURV GB 70, 10–22.Google Scholar
Meighan, I. G., Gibson, D. & Hood, D. N. 1984. Some aspects of Tertiary acid magmatism in NE Ireland. MINERAL MAG 48, 351–63.CrossRefGoogle Scholar
Meighan, I. G., McCormick, A. G., Gibson, D., Gamble, J. A. & Graham, I. J. 1988. Rb-Sr isotopic determinations and the timing of Tertiary central complex magmatism in NE Ireland. In Morton, A. C. & Parson, L. M. (eds) Early Tertiary Volcanism and the Opening of the NE Atlantic, 349–60. SPEC PUBL GEOL SOC LONDON 39.CrossRefGoogle Scholar
Menzies, M. A., Halliday, A. N., Palacz, Z., Hunter, R. H., Upton, B. G. J., Aspen, P. & Hawkesworth, C. J. 1987. Evidence from mantle xenoliths for an enriched lithospheric keel under the Outer Hebrides. NATURE 325, 44–7.CrossRefGoogle Scholar
Mussett, A. E., Dagley, P. & Skelhorn, R. R. 1988. Time and duration of activity in the British Tertiary Igneous Province. In Morton, A. C. & Parson, L. M. (eds) Early Tertiary Volcanism and the Opening of the NE Atlantic, 337–48. SPEC PUBL GEOL SOC LONDON 39.CrossRefGoogle Scholar
Pankhurst, R. J., Walsh, J. N., Beckjnsale, R. D. & Skelhorn, R. R. 1978. Isotopic and other geochemical evidence for the origin of the Loch Uisg Granophyre, Isle of Mull, Scotland. EARTH PLANET SCI LETT 38, 355–63.CrossRefGoogle Scholar
Richey, J. E. 1928. The structural relations of the Mourne granites (Northern Ireland). Q J GEOL SOC LONDON 83, 653–88.CrossRefGoogle Scholar
Sigmarsson, O., Hémond, C., Condomines, M., Fourcade, S. & Oskarsson, N. 1991. Origin of silicic magma in Iceland revealed by Th isotopes. GEOLOGY 19, 621–4.2.3.CO;2>CrossRefGoogle Scholar
Sparks, R. S. J. 1988. Petrology and geochemistry of the Loch Ba ring dyke, Mull (N.W. Scotland): an example of extreme differentiation of tholeiitic magmas. CONTRIB MINERAL PETROL 100, 446–61.CrossRefGoogle Scholar
Stone, M. 1988. The significance of almandine garnets in the Lundy and Dartmoor granites. MINERAL MAG 52, 651–8.CrossRefGoogle Scholar
Stone, M. 1990. The Lundy granite: a geochemical and petrogenetic comparison with Hercynian and Tertiary granites. MINERAL MAG 54, 431–46.CrossRefGoogle Scholar
Taylor, H. P. Jr & Forester, R. W. 1971. Low-O18 Igneous Rocks from the Intrusive Complexes of Skye, Mull and Ardnamurchan, Western Scotland. J PETROL 12, 465–97.CrossRefGoogle Scholar
Thompson, R. N. 1982. Magmatism of the British Tertiary Volcanic Province. SCOTT J GEOL 18, 49–107.CrossRefGoogle Scholar
Thompson, R. N., Gibson, I. L., Marriner, G. F., Mattey, D. P. & Morrison, M. A. 1980. Trace-Element Evidence of Multistage Mantle Fusion and Polybaric Fractional Crystallization in the Palaeocene Lavas of Skye, NW Scotland. J PETROL 21, 265–93.CrossRefGoogle Scholar
Thompson, R. N. & Morrison, M. A. 1988. Asthenospheric and lower-lithospheric mantle contributions to continental extensional magmatism: An example from the British Tertiary Province. CHEM GEOL 68, 1–15.CrossRefGoogle Scholar
Thorpe, R. S., Tindle, A. G. & Gledhill, A. 1990. The Petrology and Origin of the Tertiary Lundy Granite (Bristol Channel, UK). J PETROL 31, 1379–406.CrossRefGoogle Scholar
Thy, P., Beard, J. S. & Lofgren, G. E. 1990. Experimental constraints on the origin of Icelandic rhyolites. J GEOL 98, 417–21.CrossRefGoogle Scholar
Walsh, J. N., Beckinsale, R. D., Skelhorn, R. R. & Thorpe, R. S. 1979. Geochemistry and Petrogenesis of Tertiary Granitic Rocks from the Island of Mull, Northwest Scotland. CONTRIB MINERAL PETROL 71, 99–116.CrossRefGoogle Scholar
White, R. S. & McKenzie, D. P. 1989. Magmatism at rift zones: the generation of volcanic continental margins and flood basalts. J GEOPHYS RES 94, 7685–729.CrossRefGoogle Scholar