Abstract
Analyses of Moine metasediments and migmatites in the Loch Coire area of northern Scotland are used to delineate the fields of composition of the major rock groups. An assessment is made of the relative merits of the hypotheses of isochemical metamorphism and metasomatism in the genesis of the migmatites. Within the migmatites the Fe″/Fe‴ ratio is constant, a feature not shown by the metasediments. This is interpreted as evidence of permeation of the migmatites by metasomatising fluids. Granitic sheets which are common in the migmatites have a very variable and predominantly sodium-rich composition more easily reconciled with metasomatism than a simple magmatic or anatectic origin. Attention is also drawn to the sodic nature of the large mass of Loch Coire granite which occurs in the centre of the migmatite area and the possibility is considered that the uprise of sodic magma provided sodium-rich fluids for permeation of the rest of the complex.
Similar content being viewed by others
References
Barth, T. F. W.: Oxygen in rocks: a basis for petrographic calculation. J. Geol. 56, 50–60 (1948).
—: Principles of classification and norm calculations of metamorphic rocks. J. Geol. 67, 135–152 (1959).
Bennet, H., W. G. Hawley, and R. P. Eardley: Rapid analysis of some silicate materials. Trans. Brit. Ceram. Soc. 19, 413–428 (1958).
Butler, B. C. M.: Metamorphism and metasomatism of rocks of the Moine Series by a dolerite plug in Glenmore, Ardnamurchan. Mineral. Mag. 32, 866–897 (1961).
—: A chemical study of some rocks of the Moine Series of Scotland. Quart. J. Geol. Soc. London 121, 163–208 (1965).
Cheng, Y.: The migmatite area around Bettyhill, Sutherland. Quart. J. Geol. Soc. London 99, 107–154 (1944).
Jahns, R. H., and C. W. Burnham: Experimental studies of pegmatite genesis: Melting and crystallization of granite and pegmatite. Bull. Geol. Soc. Am. 69, 1592–1593 (1958).
Jeffrey, P. G., and A. D. Wilson: A combined gravimetric and photometric procedure for determining silica in silicate minerals and rocks. Analyst 85, 478–486 (1960).
Luth, W. C., R. H. Jahns, and O. F. Tuttle: The granite system at pressures of 4 to 10 Kilobars. J. Geophys. Research 69, 759–773 (1964).
Orville, P. M.: Alkali ion exchange between vapor and feldspar phases. Am. J. Sci. 261, 201–237 (1963).
Peach, B. N. et al.: The geology of Ben Wyvis, Carn Chuinneag, Inchbae and the sursounding country. Mem. Geol. Survey G.B. (1912).
Read, H. H.: The geology of Central Sutherland. Mem. Geol. Surv. G.B. (1931).
—: Aspects of the Caledonian magmatism in Britain. Liver. and Manch. Geol. J. 2, 653–683 (1961).
J. Phemister, and G. Ross: The geology of Strath Oykell and Lower Loch Shin. Mem. Geol. Surv. G.B. (1926).
—, and J. Watson: Introduction to geology. London: Macmillan & Co. Ltd. 1962.
Riley, J. P.: The rapid analysis of silicate rocks and minerals. Anal. Chim. Acta 19, 413–428 (1958).
Soper, N. J.: The structure of the Rogart igneous complex. Quart. J. Geol. Soc. London 119, 445–476 (1963).
Tuttle, O. F., and N. L. Bowen: Origin of granite in the light of experimental studies in the system NaAlSi3O8-KAlSi3O8-SiO2-H2O. Mem. Geol. Soc. Am. 74 (1958).
Wilson, G., J. Watson, and J. Sutton: Current bedding in the Moine Series of north-western Scotland. Geol. Mag. 90. 377–387 (1953).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Brown, P.E. Major element composition of the Loch Coire migmatite complex, Sutherland, Scotland. Contr. Mineral. and Petrol. 14, 1–26 (1966). https://doi.org/10.1007/BF00370983
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00370983