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V.—The Geochemistry of the Older Granodiorite, Co. Donegal, Ireland*

Published online by Cambridge University Press:  30 May 2017

Edward L. P. Mercy
Edward L. P. Mercy*
Affiliation:
Grant Institute of Geology, University of Edinburgh
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Synopsis

Chemical analysis of samples of the Older Granodiorite, Co. Donegal, Ireland, shows that it has a geographical variation in which Si, K and O increase, Na is about constant and all other major elements decrease in amount from east to west. There is a high degree of positive linear correlation between Mg and Fe2 + Fe3 which implies derivation of these elements from some previously existing ferromagnesiam mineral in which the appropriate ratio was maintained. There is a low degree of negative linear correlation between Na and K which implies that these elements are mobile and independent of each other.

The chemical relationships of the granodiorite to its pelitic country rocks are shown and discussed. The relations are such that the preferred hypothesis for the origin of the granodiorite is one of influx of Na, K and Ca ions in an alumino-silicate medium. Country rocks are diluted by this influx and it is unnecessary to assume any great migration of Mg and Fe. With time the nature of the influx changes—Ca decreases in amount whereas Na, K and Si all increase but K and Si to a very much greater extent than Na.

Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 64 , Issue 5-6: 1958-1959 The Geochemistry of the Older Granodiorite and of the Rosses Granitic Ring Complex, Co. Donegal, Ireland , 1960 , pp. 101 - 127
Copyright
Copyright © Royal Society of Edinburgh 1959

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Footnotes

*

This paper was assisted in publication by a grant from the Carnegie Trust for the Universities of Scotland. Trans. Roy. Soc. Edin., Vol. LXIV, No. 5, 1958–59

References

References to Literature

SirBailey, E. B., 1958. “Some Chemical Aspects of South-west Highland Devonian Igneous Rocks”, Bull. Geol. Surv. G.B., 15, 1–20.Google Scholar
Barth, T. P. W., 1955. “Presentation of Rock Analyses”, J. Geol, 63, 348–363.CrossRefGoogle Scholar
Eskola, P., 1954. “A Proposal for the Presentation of Analyses in Ionic Percentages”, Ann. Acad. Sci. Fenn. (A III), 38, 15 pp.Google Scholar
Gindy, A. R., 1953. “The Plutonic History of the District around Trawenagh Bay, Co. Donegal”, Quart. J. Geol. Soc. Lond., 108, 377–412.Google Scholar
Geoves, A. W., 1951. Silicate Analysis, chap. III. London.Google Scholar
Iyengae, S. V. P., et al., 1954. “The Plutonic History of the Maas Area, Co. Donegal”, Quart. J. Geol. Soc. Lond., 110, 203–230.Google Scholar
Mercy, E. L. P., 1956. “The Accuracy and Precision of the ‘Rapid Methods’ of Analysis”, Geochim. et Cosmoch. Acta, 9, 161–173.Google Scholar
Nockolds, S. R., and Allen, R., 1953. “The Geochemistry of Some Igneous Rock Series”, Geochim. et Cosmoch. Acta, 4, 105–142.Google Scholar
Pitches, W. S., 1953a. “The Migmatitic Older Granodiorite of Thorr District, Co. Donegal”, Quart. J. Geol. Soc. Lond., 108, 413–436.Google Scholar
Pitches, W. S., 1953b. “The Rosses Granitic Ring Complex, Co. Donegal, Eire”, Proc. Geol. Ass. Lond., 64, 153–179.Google Scholar
Pitchee, W. S., and Read, H. H., 1958. “The Main Donegal Granite”, Quart. J. Geol. Soc. Lond., 114, 259–300.Google Scholar
Pitchee, W. S., and Sinha, R. C., 1957. “The Petrochemistry of the Ardara Aureole”, Quart. J. Geol. Soc. Lond., 113, 393–407.Google Scholar
Reynolds, D. L., 1946. “The Sequence of Geocheniical Changes Leading to Granitization”, Quart. J. Geol. Soc. Lond., 102, 389–448.Google Scholar
Shapiro, L., and Brannock, W. W., 1952. “Rapid Analysis of Silicate Rocks”, Circ. U.S. Geol. Surv., 165.Google Scholar
Shapiro, L., and Brannock, W. W., 1956. “Rapid Analysis of Silicate Rocks”, Bull. U.S. Geol. Surv., 1036-C.Google Scholar
Tuttle, O. F., and Bowen, N. L., 1958. “Origin of Granite in the Light of Experimental Studies in the System NaAlSi3O8-KAlSi3O8-SiO2-H2O”, Mem. Geol. Soc. Amer., 74, 153 pp.Google Scholar
Whitten, E. H. T., 1952. Geology of the Metamorphic and Plutonic Rocks of the Gweedore Area, Co. Donegal, Eire. Ph.D. Thesis, Lond. Univ.Google Scholar