Hostname: page-component-cd9895bd7-7cvxr Total loading time: 0 Render date: 2024-12-23T15:40:42.315Z Has data issue: false hasContentIssue false
  • English
  • Français

A re-evaluation of the blueschist facies

Part 2. The role of the mineral in metamorphism

Published online by Cambridge University Press:  01 May 2009

R. M. Wood
R. M. Wood
Affiliation:
Department of Mineralogy and Petrology, Downing Place, Cambridge
Get access Rights & Permissions [Opens in a new window]

Summary

Within blueschist facies rocks it is common to find that mineral assemblages represent a series of attempts to arrive at changing states of equilibrium. To interpret such rocks it is necessary to study how the mineral constrains and determines chemical interaction. The gradual process of chemical exchange between minerals, during changes in conditions, is interrupted by the nucleation of a new mineral species. Mineral reactions are instigated by the nucleation of one new mineral species, though when a reaction is seen at an equilibrated completion the reaction path cannot be traced. In low temperature metamorphism the preservation of partial mineral reactions is very widespread. The growth, adaptation and resorption of a mineral are considered in order to demonstrate: (1) how and why a mineral should zone during growth: (2) the competitive reaction paths that may allow a mineral to change composition, even across and internal solvus; and, (3) through the consideration of a few simple parameters, the prediction of a variety of resorption textures. It is proposed that through an understanding of the way in which the mineral can store information on the chemical history of the rock it is possible to obtain a metamorphic analysis without recourse to the conventional phase equilibrium metamorphic model - a frequent misapplication in the blueschist facies.

Type
Articles
Information
Geological Magazine , Volume 116 , Issue 3 , May 1979 , pp. 191 - 201
Copyright
Copyright © Cambridge University Press 1979

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Atherton, M. P. & Edmunds, W. A. 1966. An electron micro-probe study of some zoned garnets from metamorphic rocks. Earth Planet. Sci. Lett. 1, 185–94.CrossRefGoogle Scholar
Barrer, R. M. 1974. Isomorphous replacement by ion exchange: some equilibrium aspects. Bull. Soc. fr. Min. Crist. 97, 89–100.Google Scholar
Carmichael, D. M. 1969. On the mechanism of prograde metamorphism in quartz bearing pelitic rocks. Contr. Miner. Petrol. 20, 244–67.CrossRefGoogle Scholar
Cooper, A. F. 1972. Progressive metamorphism of metabasic rocks from the Haast River Schist Group of Southern New Zealand. J. Petrology 13, 457–92.CrossRefGoogle Scholar
Fisher, G. W. 1973. Non-equilibrium thermodynamics as a model for diffusion controlled metamorphic processes. Am. J. Sci. 273, 897–924.CrossRefGoogle Scholar
Harmony, M. D. 1972. Quantum mechanical tunnelling in chemistry. Chem. Review 1, 211–28.Google Scholar
Hollister, L. S. 1966. Garnet zoning: An interpretation based on the Rayleigh fractionation model. Science 154, 1647–51.Google Scholar
Leake, B E. 1972. The mineralogical modification of the chemistry of metamorphic rocks. Geol. Mag. 109, 331–7.Google Scholar
Lin, H. L. & Yund, R. A. 1971. Potassium and sodium self-diffusion in alkali feldspars. Contr. Miner. Petrol. 34, 177–84.CrossRefGoogle Scholar
MacKenzie, W. S. 1973. In The Feldspars (ed. MacKenzie, & Zussman, ). Manchester University Press.Google Scholar
McConnell, J. D. C. 1975. Microstructures of minerals as petrogenetic indicators. Anni Rev. Earth Planet. Sci. 3, 129–55.CrossRefGoogle Scholar
Orville, P. M. 1962. Alkali metasomatism in feldspars. Norsk. geol. Tidsskr. 42, 283–316.Google Scholar
Slaughter, J., Kerrick, D. M. & Wall, V. J. 1975. Experimental and thermodynamic study of equilibrium in the system CaO-MgO-SiO2-H2O-CO2. Am. J. Sci. 275, 143–62.Google Scholar
Smellie, J. A. T. 1974. Formation of atoll garnets from the aureole of the Ardara pluton, Co. Donegal, Ireland. Mineralog. Mag. 39, 878–88.Google Scholar
Sureau, J.-F. 1974. Etude expérimentale de la dolomitisation de la calcite. Bull. Soc. fr. Min. Crist. 97, 300–12.Google Scholar
Thompson, J. B. Jnr. 1957. The graphical analysis of mineral assemblages in pelitic schists. Am. Miner. 42, 842–58.Google Scholar
Viswanathan, K. 1971. A new X-ray method to determine the anorthite content and structural state of plagioclase. Contr. Miner. Petrol. 30, 332–35.CrossRefGoogle Scholar