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VI.—The Geochemistry of the Rosses Granitic Ring Complex, 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

The members of the Rosses Granitic Ring Complex have been chemically analyzed. The data are presented as averages with 95 per cent confidence limits for individual elements. A limited amount of crystallization differentiation is demonstrated when the major units—the biotite microgranite sheets, the porphyry dykes, the ring granites and the grey and pink microgranite sheets—are compared with one another. This involves an increase in Si, K, a decrease in Ti, Al, Fe, Mg, Ca and P, but Na (and Mn) remain constant. The ring granites G1-G4 undergo very little differentiation and variations in their composition, except for Si, are ascribed mainly to heterogeneity.

The origin of the magma which gave rise to the complex is due to the palingenesis of the Older Granodiorite under the influence of a Na, K, alumino-silicate influx. This magma was the source of the biotite microgranite sheets and, after differentiation, the granites G1 and G2, together with some of the grey and pink microgranite sheets. After a period of quiescence a second influx produced the similar magma which was the source of the porphyry dykes and, after differentiation, gave rise to the granites G3 and G4, the Newer Granite bosses and the late grey and pink microgranite sheets.

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. 128 - 138
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.

References

References to Literature

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