Hostname: page-component-78c5997874-mlc7c Total loading time: 0 Render date: 2024-11-10T07:04:01.337Z Has data issue: false hasContentIssue false
  • English
  • Français

The eastern end of the Galway granite

Published online by Cambridge University Press:  05 July 2018

J. S. Coats  and
J. R. Wilson
J. S. Coats
Affiliation:
Department of Geology, University of Bristol, Bristol BS8 1TR
J. R. Wilson
Affiliation:
Department of Geology, University of Bristol, Bristol BS8 1TR
Get access Rights & Permissions [Opens in a new window]

Summary

An account of the eastern part of the Galway Granite is presented together with the first detailed geological map. An aphyric medium-grained alkali granite occurs at the margin of the pluton followed by a coarse porphyritic granite, which becomes more basic towards the granite centre, consistent with findings in the western and northern parts of the batholith. Westwards the coarse porphyritic granite develops a foliation in which xenoliths, and occasionally potash feldspar phenocrysts, are aligned. Chemical fractionation trends illustrate the consanguinity of the granites and aplites. Field, petrographic, and chemical evidence suggest that most of the xenoliths are cognate.

The zonation of the granite is thought to have resulted from crystallization of a magma in which compositional gradients were set up during the early crystallization period. A temperature gradient, decreasing from the centre of the magma chamber outwards into the country rocks, resulted in the migration of water, accompanied by alkalis and other volatiles, towards the granite margin; also the early-crystallizing minerals displaced the residual magma outwards. Crystallization was followed by shearing in the deeper parts of the pluton to produce the granite foliation. A total of 166 rocks have been chemically analysed for 31 constituents.

Type
Research Article
Information
Mineralogical Magazine , Volume 38 , Issue 294 , June 1971 , pp. 138 - 151
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2013

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

1

Present address: Institute of Geological Sciences, 64-78 Grays Inn Road, London, W.C.I.

2

Present address: Geologisk Institut, Aarhus Universitet, Aarhus, Denmark.

References

Aucott, (J.W.), 1966. Ph.D. thesis, University of Bristol.Google Scholar
Azzaria, (L.M.), 1962. Canad. Min. 7, 617.Google Scholar
Brammall, (A.) and Harwood, (H.F.), 1932. Min. Mag. 20, 4.o.Google Scholar
Burke, (K.C.), 1957. Geol. Mag. 94, 452.CrossRefGoogle Scholar
Claxton, (C.W.), 1965. Ph.D. thesis, University of Hull.Google Scholar
Claxton, (C.W.), 1968. Geol. Mag. 105, 149.CrossRefGoogle Scholar
Coats, (J.S.), 1970. Ph.D. thesis, University of Bristol.Google Scholar
Cole, (G. A. J.), 1915. Quart. Journ. Geol. Soc. 71, 183.CrossRefGoogle Scholar
Emeleus, (C.H.), 1963. Min. Soc. Amer. Special paper 1, 22.Google Scholar
Hahn-Weinheimer, (P.) and Ackerman, (H.), 1967. Geochimica Acta, 31, 2197.CrossRefGoogle Scholar
Haskin, (L.A.), Frey, (F.A.), Schmitt, (R.A.), and Smith, (R.H.), 1966. Phys. Chem. Earth, 7, 169.CrossRefGoogle Scholar
Kinahan, (G.H.), 1869. Mem. Geol. Surv. Ireland, Sheets 105 and 114.Google Scholar
Lawrence, (G.), 1968. Ph.D. thesis, University of Bristol.Google Scholar
Leake, (B.E.), 1968. Earth Planet Sci. Lett. 3, 311.CrossRefGoogle Scholar
Leake, (B.E.), and Leggo, (P.J.), 1963. Geol. Mag. 100, 193.CrossRefGoogle Scholar
Leake, (B.E.), Hendry, (G.L.), Kemp, (A.), Plant, (A.G.), Harvey, (P.K.), Wilson, (J.R.), COATS (J. S.), Aucott, (J.W.), Lonel, (T.), and Howarth, (R.J.), 1969. Chem. Geol. 5, 7.CrossRefGoogle Scholar
Leggo, (P.J.), 1963. Ph.D. thesis, University of Bristol.Google Scholar
Leggo, (P.J.), Comvston, (W.), and Leake, (B.E.), 1966. Quart. Journ. Geol. Soc. 122, 91.CrossRefGoogle Scholar
Mckie, (D.) and Burke, (K.C.), 1955. Gëol Mag. 92, 487.Google Scholar
Morton, (D.M.), 1969. Geol. Soc. Amer. Bull. 80, 1539.CrossRefGoogle Scholar
Morton, (D.M.), Baird, (A.K.), and Baird, (K.W.), 1969. Ibid. 80, 1553.Google Scholar
Mursky, (G.), 1968. Prog. Abstr. Geol. Soc. Amer. Annual Meeting, New Orleans, 159.Google Scholar
Parslow, (G.), 1969. Min. Mag. 37, 262.CrossRefGoogle Scholar
Pidgeon, (R.T.), 1969. Scott. Journ. Geol. 5, 375.CrossRefGoogle Scholar
Ragland, (P.C.), Billings, (G.K.), and ADAMS (J. A. S.), 1967. Geochimica Acta, 31, 17.CrossRefGoogle Scholar
Ragland, (P.C.), Billings, (G.K.), and ADAMS (J. A. S.), 1968. In Origin and Distribution of the Elements. Ed. AHRENS, L. H., Oxford, 795.CrossRefGoogle Scholar
Streckeisen, (A.L.), 1967. Neues Jahrb. Min. Abh. 107, 144.Google Scholar
Taylor, (S.R.), 1965. Phys. Chem. Earth, 6, 133.CrossRefGoogle Scholar
Townend, (R.), 1966. Proc. Roy. Irish Acad. 65, 157.Google Scholar
Tuttle, (O.F.) and Bowen, (N.L.), 1958. Geol. Soc. Amer. Mem. 74.Google Scholar
Wager, (L.R.), 1932. Proc. Roy. lrish Acad. 41, 46.Google Scholar
Wilson, (J.R.), 1969. Ph.D. thesis, University of Bristol.Google Scholar
Wright, (P.C.), 1961. Ph.D. thesis, University of Bristol.Google Scholar
Wright, (P.C.), 1964. Proc. Roy. lrish Acad. 63, 239.Google Scholar