Hostname: page-component-8448b6f56d-jr42d Total loading time: 0 Render date: 2024-04-25T01:42:11.044Z Has data issue: false hasContentIssue false
  • English
  • Français

Some aspects of Tertiary acid magmatism in NE Ireland

Published online by Cambridge University Press:  05 July 2018

I. G. Meighan ,
D. Gibson  and
D. N. Hood
I. G. Meighan
Affiliation:
Department of Geology, The Queen's University of Belfast, Belfast, BT7 INN, Northern Ireland
D. Gibson
Affiliation:
Department of Geology, The Queen's University of Belfast, Belfast, BT7 INN, Northern Ireland
D. N. Hood
Affiliation:
Department of Geology, The Queen's University of Belfast, Belfast, BT7 INN, Northern Ireland
Get access Rights & Permissions [Opens in a new window]

Abstract

Geochemical data (including REE determinations) are presented for all five Mourne Mountains granites and three Northern Ireland rhyolites. These confirm (1) the extremely fractionated nature of some of the rocks (Sr and Ba < 10 ppm, Rb > 400 ppm, Eu/Eu* < 0.1, and K/Rb < 100), and (2) a major revision to the outcrops of the E. Mourne granites G1 and G2 in which much of the former is reclassified as G2. Combined petrographic and geochemical studies have also indicated that magmatic pulses were involved in the emplacement of Mourne intrusions G2 (Revised)-G5 inclusive.

The N. Ireland Tertiary acid rocks exhibit general geochemical similarities to their analogues elsewhere in the British Tertiary Igneous Province (in which Sr is generally < 100 ppm and CeN/YbN generally < 8 with Eu/Eu* often < 0.6), but as a suite the Mourne granites are enriched in Rb and some other LIL elements relative to their N. Arran counterparts.

The more fractionated acid magmas of NE Ireland are believed to have evolved from primitive granitic parent liquids by crystal fractionation at depth which involved major and accessory phases (including zircon and allanite). In the Mourne (and County Antrim) areas the primitive acid compositions lie at the ends of basaltic (tholeiitic) differentiation series, and in the Mourne central complex there is a complete geochemical sequence from basic rocks through intermediate members to primitive and ultimately highly evolved, subalkaline, granitic intrusions. It is concluded that the data are consistent with the Mourne granites and Northern Ireland rhyolites being essentially basaltic differentiates, although Sr isotope evidence indicates some (probably minor) crustal involvement.

Type
Research Article
Information
Mineralogical Magazine , Volume 48 , Issue 348 , September 1984 , pp. 351 - 363
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1984

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.)

Footnotes

†

Present address: Esso Exploration and Production UK Limited, Biwater House, Portsmouth Road, Esber, Surrey KT10 9SJ.

References

Akiman, O. (1971) The petrology and geochemistry of the Tertiary dyke swarm associated with the Moume Mountains granites, N. Ireland. Ph.D. thesis, Univ. of Durham.Google Scholar
Brooks, C. K., Henderson, P., and Ransbo, J. G. (1981) Mineral. Mag. 44, 157-60.CrossRefGoogle Scholar
Brown, P. E. (1956) Geol. Mag. 93, 72–84.CrossRefGoogle Scholar
Burt, D. M., Sheridan, M. F., Bikun, J. V., and Christiansen, E. H. (1982) Econ. Geol. 77, 1818-36.CrossRefGoogle Scholar
Carmichael, I. S. E., Turner, F. J., and Verhoogen, J. (1974) Igneous Petrology. McGraw-Hill Book Company.Google Scholar
Dickin, A. P., Exley, R. A., and Smith, B. M. (1980) Earth Planet. Sci. Lett. 51, 58–70.CrossRefGoogle Scholar
Dickin, A. P., Moorbath, S., and Welke, H. J. (1981) Trans. R. Soc. Edinburgh. 72, 159-70.CrossRefGoogle Scholar
Dufifield, J., and Gilmore, G. R. (1979) J. Radioanal. Chem. 48, 135-45.CrossRefGoogle Scholar
Emeleus, C. H. (1955) Sci. Proc. R. Dublin Soc. 27, 35–50.Google Scholar
Harry, W. T., and Richey, J. E. (1963) Liverpool Manchester Geol. J. 3, 254-68.CrossRefGoogle Scholar
Hildreth, W. (1979) Spec. Pap. Geol. Soc. Am. 180, 43–75.Google Scholar
Hildreth, W. (1981) J. Geophys. Res. 86, 10153-92.CrossRefGoogle Scholar
Hood, D. N. (1981) Geochemical, Petrological and Structural Studies on the Tertiary Granites and Associated Rocks of the Eastern Mourne Mountains, Co. Down, Northern Ireland. Ph.D. thesis, The Queen's Univ. of Belfast.Google Scholar
Hood, D. N., Meighan, I. G., Gibson, D., and McCormick, A. G. (1981) J. Geol. Soc. London. 138, 497.Google Scholar
Lyle, P. (1980) J. Earth Sci. R. Dublin Soc. 2, 137-52.Google Scholar
Lyle, P. and Thompson, S. J. (1983) Scott. J. Geol. 19, 17–27.CrossRefGoogle Scholar
McCormick, A. G., Harmon, R. S., and Meighan, I. G. (1980) Geol. Soc. Am. Abstracts with Programs. 12, 479.Google Scholar
Meighan, I. G. (1976) J. Geol. Soc. London. 132, 700.Google Scholar
Meighan, I. G. (1979) Bull. Geol. Surv. G.B. No. 70, 10–22.Google Scholar
Meighan, I. G. (1981) The Petrogenesis of the Acid Igneous Rocks of the British Tertiary Province. Ph.D. thesis, The Queen's Univ. of Belfast.Google Scholar
Meighan, I. G. and Gamble, J. A. (1972) Nature (Phy. Sci.) 240, 183-4.Google Scholar
Meighan, I. G. and Neeson, J. C. (1979) In The Caledonides of the British Isles—reviewed (Harris, A. L., Holland, C. H., and Leake, B. E., eds.). Spec. Publ. Geol. Soc. London No. 8, 717-22.Google Scholar
Miller, C. F., and Mittlefehldt, D. W. (1982) Geology. 10, 129-33.2.0.CO;2>CrossRefGoogle Scholar
Morrison, M. A., Thompson, R. N., Gibson, I. L., and Marriner, G. F. (1980) Phil. Trans. R. Soc. London, A297, 229-44.Google Scholar
Nakamura, N. (1974) Geochim. Cosmochim. Acta. 38, 757-75.CrossRefGoogle Scholar
Old, R. A. (1975) Bull. Geol. Surv. G.B. No. 51, 21–40.Google Scholar
Pankhurst, R. J., Walsh, J. N., Beckinsale, R. D., and Skelhorn, R. R. (1978) Earth Planet. Sci. Lett. 38, 355-63.CrossRefGoogle Scholar
Richey, J. E. (1928) Q. J. Geol. Soc. London. 83, 653-88.CrossRefGoogle Scholar
Tammemagi, H. Y. (1976) Geol. Mag. 113, 271-6.CrossRefGoogle Scholar
Taylor, H. P. Jr., and Forester, R. W. (1971) J. Petrol. 12, 465-97.CrossRefGoogle Scholar
Thompson, R. N. (1980) Geol. Rdsch. 69, 245-62.CrossRefGoogle Scholar
Thompson, R. N. (1982) Scott. J. Geol. 18, 49–107.CrossRefGoogle Scholar
Walsh, J. N., and Clarke, E. (1982) Mineral. Mag. 45, 247-55.CrossRefGoogle Scholar
Walsh, J. N., Beckinsale, R. D., Skelhorn, R. R., and Thorpe, R. S. (1979) Contrib. Mineral. Petrol. 71, 99-116.CrossRefGoogle Scholar
Walsh, J. N., Buckley, F., and Barker, J. (1981) Chem. Geol. 33, 141-53.CrossRefGoogle Scholar