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Facies Boundaries in Pelites at the Middle Grades of Regional Metamorphism

Published online by Cambridge University Press:  01 May 2009

G. H. Francis
Affiliation:
Department of Mineralogy, British Museum (Natural History), South Kensington, S.W. 7.

Abstract

An examination of existing definitions of facies and subfacies boundaries in pelitic rocks suggests that some alteration is necessary to emphasize two important reactions:

3 Staurolite + 2 Quartz ⇌ Almandine + 5 Al2SiO5 + 3 Water, and

Muscovite + Quartz ⇌ Potash feldspar + Al2SiO5 + Water A generalized plot shows possible relations between the curves of these two reactions and the inversion, curves of the aluminosilicates within the P-T field of metamorphism. The curves of further reactions commonly used to define facies and subfacies boundaries have been schematically added to this plot, and trends of metamorphism in various areas are indicated thereon. P-T curves of dehydration reactions such as the above will vary according to the chemical potential of the water vapour in each particular case. Observations suggest, however, that the curves are not very differently placed from one regional metamorphic terrain to another. That is, the rate of escape of volatiles is broadly similar in the metamorphism of many of these terrains.

Type
Articles
Copyright
Copyright © Cambridge University Press 1956

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References

REFERENCES

Alderman, A. R., 1950. The Genesis of Sillimanite and Kyanite Rocks by Alumina Metasomatism. Int. Geol. Cong. Rept. XVIIIth Session, 1948, Pt. III, 125–6.Google Scholar
Barrow, G., 1893. On an Intrusion of Muscovite-Biotite Gneiss in the South-east Highlands of Scotland. Quart. Journ. Geol. Soc., xlix, 330358.CrossRefGoogle Scholar
Barrow, G. 1912. On the geology of Lower Dee-side and the southern Highland border. Proc. Geol. Assoc., xxiii, 268284.CrossRefGoogle Scholar
Bowen, N. L., 1940. Progressive Metamorphism of Silicious Limestone and Dolomite. Journ. Geol., xlviii, 225274.CrossRefGoogle Scholar
Billings, M. P., 1950. Field and Laboratory methods in the study of metamorphic rocks. N.Y. Acad. Sci., Tr., ser. II, xiii, 4451.CrossRefGoogle Scholar
Chapman, C. A., 1952. Structure and Petrology of the Sunapee Quadrangle, New Hampshire. Geol. Soc. Amer. Bull., lxiii, 381426.CrossRefGoogle Scholar
Ch'ih, C. S., 1950. Structural Petrology of the Wissahickon Schist near Philadelphia, Pennsylvania, with Special Reference to Granitization. Geol. Soc. Amer. Bull., lxi, 923, 956.CrossRefGoogle Scholar
Davidson, C. F., 1943. The Archaean Rocks of the Rodil district, South Harris, Outer Hebrides. Tr. Roy. Soc. Edin., lxi, 71112Google Scholar
Ellitsgaard-Rasmussen, K., 1954. On the Geology of a Metamorphic Complex in West Greenland. Medd. om Grønland, cxxxvi, No. 6.Google Scholar
Harker, A., 1939. Metamorphism. 2nd Edn., Methuen, London.Google Scholar
Harker, R. I., 1954. Further Data on the Petrology of the Pelitic Hornfelses of the Cam Chuinneag-Inchbae Region, Ross-shire, with special reference to the Status of Almandine. Geol. Mag., xci, 445462.CrossRefGoogle Scholar
Hinxman, L. W. et al. , 1915. The Geology of Mid Strathspey and Strathdearn. Geol. Surv. Scotland. Mem. 74.Google Scholar
Miyashiro, A., 1949. The stability relation of kyanite, sillimanite and andalusite and the physical condition of metamorphic processes. Geol. Soc. Japan Journ., lv, 218223.Google Scholar
Miyashiro, A. 1953. Calcium-poor garnet in relation to metamorphism. Geochim. et Cosmochim. Acta, iv, 179208.CrossRefGoogle Scholar
Miyashiro, A. et al. , 1955. The Polymorphism of Cordierite and Indialite. Amer. Journ. Sci., ccliii, 185205.CrossRefGoogle Scholar
Ramberg, H., 1952. The Origin of Metamorphic and Metasomatic Rocks. Univ. of Chicago Press, Chicago.Google Scholar
Read, H. H., 1923. The Geology of the Country Round Banff, Huntly and Turriff. Geol. Surv. Scotland. Mem. 89, 96.Google Scholar
Read, H. H. 1934. The Metamorphic Geology of Unst in the Shetland Islands. Quart. Journ. Geol. Soc., xc, 637688.CrossRefGoogle Scholar
Streckeisen, A., 1928. Geologic und Petrographie der Flüelagruppe (Graübunden). Schweiz. Min.-Petrogr. Mitt., viii, 87239.Google Scholar
Suzuki, J., 1930. Ueber die Staurolith-Andalusite Paragenesis im Glimmergneis von Piodina bei Brissago (Tessin). Schweiz. Min.-Petrogr. Mitt., x, 117132.Google Scholar
Thompson, J. B. Jr., 1955. The Thermodynamic Basis for the Mineral Fades Concept. Amer. Journ. Sci., ccliii, 65103.CrossRefGoogle Scholar
Tilley, C. E., 1925 a. Metamorphic Zones in the Southern Highlands of Scotland. Quart. Journ. Geol. Soc., lxxxi, 100112.CrossRefGoogle Scholar
Tilley, C. E. 1925 b. Petrographical Notes on some Chloritoid Rocks. Geol. Mag., lxii, 309319.CrossRefGoogle Scholar
Tozer, C. F., 1955. The Mode of Occurrence of Sillimanìte in the Glen District, Co. Donegal. Geol. Mag., xcii, 310320.CrossRefGoogle Scholar
Turner, F. J., 1948. Minerahgical and Structural Evolution of the Metamorphic Rocks. Geol. Soc. Amer. Mem., xxx.Google Scholar
Turner, F. J. and Verhoooen, J., 1951. Igneous and Metamorphic Petrology. McGraw-Hill. New York.Google Scholar
Vogt, T., 1927. Sulitelmafeltets Geologi og Petrografi (with English summary). Norges Geol Undersk., No. 121, 1560.Google Scholar
Williamson, D. H., 1953. Petrology of Chloritoid and Staurolite Rocks North of Stonehaven, Kincardineshire. Geol. Mag., xc, 353361.CrossRefGoogle Scholar
Wyckoff, D., 1952. Metamorphic Facies of the Wissahickon Schist near Philadelphia, Pennsylvania. Geol. Soc., Amer. Bull., lxiii, 2558.CrossRefGoogle Scholar
Yoder, H. S. Jr., 1955. Role of Water in Metamorphism. Geol. Soc. Amer. Special Paper, lxii, 505602.Google Scholar