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Chemical variation in micas from the Cairngorm pluton, Scotland

Published online by Cambridge University Press:  05 July 2018

T. N. Harrison
T. N. Harrison*
Affiliation:
Department of Geology and Mineralogy, Marischal College, University of Aberdeen, Aberdeen AB9 1AS, Scotland
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Abstract

Electron microprobe analyses of micas from the Cairngorm pluton in the Eastern Grampian Highlands of Scotland show extensive compositional variation in biotite, despite a lack of chemical variation in the host granite. Biotite has high Fe/(Fe + Mg) (0.6–0.85) and Alvi (0.6–2.1 a.f.u.), and enrichment trends in these two parameters are attributable to the Al-Tschermak and dioctahedral-trioctahedral substitutions, the latter becoming dominant with increasing Alvi content. Ti content is low (0.2–0.4 a.f.u.), and is largely controlled by a Tschermak-type substitution. Biotite is also unusually rich in Mn (up to 2.57 wt. % MnO), which increases with both Alvi and Fe/(Fe+Mg). F contents generally range between 0.55 and 2.05 wt.% All compositional variation in biotite can be attributed to the extensive development of a fluid phase during the late-magmatic and subsolidus evolution of the pluton. The presence of an abundant fluid phase has resulted in the alteration of biotite to muscovite, which has occurred in response to de-stabilization of the biotite as octahedral R2+ cations are lost in favour of Al. Extreme build-up of this fluid phase has resulted in the crystallization of muscovite as a late, interstitial primary phase. Both primary and replacive muscovite have Fe/(Fe+Mg) > 0.50, 15–36 mol. % celadonite and <1 mol. %paragonite.

Keywords

biotitemuscovitechemical variationCairngorm plutonScotland
Type
Silicate Mineralogy
Information
Mineralogical Magazine , Volume 54 , Issue 376 , September 1990 , pp. 355 - 366
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1990

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Footnotes

*

Present address: 53½ Powis Place, Aberdeen AB2 3TT.

References

Albuquerque, C. A. R. de (1973) Geochemistry of biotites from granitic rocks, Northern Portugal. Geochim. Cosmochim. Acta, 37, 1779-802.CrossRefGoogle Scholar
Barriére, M. and Cotten, J. (1979) Biotites and associated minerals as markers of magmatic fractionation and deuteric equilibration in granites. Contrib. Mineral. Petrol. 70, 183-92.CrossRefGoogle Scholar
Burnham, C. W. (1979) Hydrothermal fluids at the magmatic stage. In Geochemistry of hydrothermal ore deposits (2nd ed.) (Barnes, H. L., ed.), 34–76.Google Scholar
Chatterjee, N. D. and Johannes, W. (1974) Thermal stability and thermodynamic properties of synthetic 2M1 muscovite, KAl2(AlSi3)O10(OH)2 . Contrib. Mineral. Petrol. 48, 89-114.CrossRefGoogle Scholar
Czamanske, G. K. and Wones, D. R. (1973) Oxidation during magmatic differentiation, Finnmarka complex, Oslo area, Norway: Part 2, the mafic silicates. J. Petrol. 14, 349-80.CrossRefGoogle Scholar
Czamanske, G. K., Ishihara, S. and Atkin, S. A. (1981) Chemistry of rock-forming minerals of the Cretaceous-Palaeocene batholith in southwestern Japan and implications for magma genesis. J. Geophys. Res. 86, 10431-69.CrossRefGoogle Scholar
Day, H. W. (1973) High-temperature stability of muscovite plus quartz. Am. Mineral. 58, 255-62.Google Scholar
Dodge, F. C. W., Smith, V. C. and Mays, R. E. (1969) Biotites from the granitic rocks of the Sierra Nevada Batholith, California. J. Petrol. 10, 250-71.CrossRefGoogle Scholar
Dymek, R. F. (1983) Titanium, aluminium and interlayer cation substitutions in biotite from high-grade gneisses, west Greenland. Am. Mineral. 68, 880-99.Google Scholar
Fenn, P. M. (1986) On the origin of graphic granite. Ibid. 71, 325-30.Google Scholar
Foster, M. D. (1960) Layer charge relations in the dioctahedral and trioctahedral micas. Ibid. 45, 383-98.Google Scholar
Harrison, T. N. (1987a) The mode of emplacement of the Cairngorm granite. Scott. J. Geol. 22, 303-14.CrossRefGoogle Scholar
Harrison, T. N. (1987b) The evolution of the Eastern Grampians granitoids. Unpubl. Ph.D. thesis, University of Aberdeen.Google Scholar
Harrison, T. N. (1988) Magmatic garnets in the Cairngorm granite, Scotland. Mineral. Mag. 52, 659-67.CrossRefGoogle Scholar
Harrison, T. N. and Hutchinson, J. (1987) The age and origin of the Eastern Grampians Newer Granites. Scott. J. Geol. 23, 269-82.CrossRefGoogle Scholar
Hazen, R. M. and Wones, D. R. (1972) Predicted and observed compositional limits of trioctahedral micas. Am. Mineral. 63, 885-92.Google Scholar
Hewitt, D. A. and Abrecht, J. (1986) Limitations on the interpretation of biotite substitutions from chemical analyses of natural samples. Ibid. 71, 1126-8.Google Scholar
Hewitt, D. A. and Wones, D. R. (1975) Physical properties of some synthetic Fe-Mg-Al trioctahedral micas. Ibid. 60, 854-62.Google Scholar
Labotka, T. C. (1983) Analysis of compositional variations of biotite in pelitic hornfelses from northeastern Minnesota. Ibid. 68, 900-14.Google Scholar
Leroy, J. and Cathelineau, M. (1982) Les minéraux phylliteaux dans les gisements hydrothermaux d'uranium. I. Cristallochimie des micas hérités et néoformés. Bull. Minéral. 105, 99-109.CrossRefGoogle Scholar
Mahood, G. and Hildreth, W. (1983) Large partition coefficients for trace elements in high-silica rhyolites. Geochim. Cosmochim. Acta, 47, 11-30.CrossRefGoogle Scholar
Miller, C. F., Stoddard, E. F., Bradfish, L. J. and Dollase, W. A. (1981) Composition of plutonic muscovite: genetic implications. Can. Mineral. 19, 25-34.Google Scholar
Monier, G. (1987) CristaUochimie des micas des leucogranites. Nouvelles données experimentales et applications pétrologiques. Geol. Geochim. Uranium (Nancy), 14.Google Scholar
Monier, G. and Robert, J.-L. (1986) Titanium in muscovites from two-mica granites: substitutional mechanism and partition with coexisting biotites. Neues Jahrb. Mineral. Abh. 153, 147-61.Google Scholar
Monier, G., Mergoil-Daniel, J. and Labernardière, H. (1984) Generations successives de muscovites et feldspaths potassiques dans les leucogranites du Millevaches (Massif Central français). Bull. Minéral. 107, 55-68.CrossRefGoogle Scholar
Nicholson, K. (1986) Mineralogy and geochemistry of manganese and iron veins, Arndilly, Banffshire. Scott. J. Geol. 23, 213-24.CrossRefGoogle Scholar
Nockolds, S. R. and Mitchell, R. L. (1946) The geochemistry of some Caledonian plutonic rocks: a study in the relationship between major and trace elements of igneous rocks and their minerals. Trans. R. Soc. Edinb. 61, 533-75.CrossRefGoogle Scholar
Robert, J.-L. (1976) Titanium solubility in synthetic phlogopite solid solutions. Chem. Geol. 17, 213-27.CrossRefGoogle Scholar
Streckeisen, A. L. (1976) To each plutonic rock its proper name. Earth Sci. Rev. 12, 1-33.CrossRefGoogle Scholar
Thompson, J. B. Jr. (1982) Compositional space: an algebraic and geometric approach. In Characterization of metamorphism through mineral equilibria (Ferry, J. M., ed.. Reviews in Mineralogy, 10, 1-32.Google Scholar
Velde, B. (1965) Phengite micas: synthesis, stability and natural occurrence. Am. J. Sci. 263, 886-913.CrossRefGoogle Scholar
Velde, B. (1972) Celadonite mica: solid solution and stability. Contrib. Mineral. Petrol. 37, 23547.CrossRefGoogle Scholar
Whittaker, E. J. W. and Muntus, R. (1970) Ionic radii for use in geochemistry. Geochim. Cosmochim. Acta, 34, 945-56.CrossRefGoogle Scholar
Zaleski, E. (1982) The geology of Speyside and lower Findhorn granitoids. Unpubl. M.Sc. thesis, University of St. Andrews.Google Scholar