Hostname: page-component-77c89778f8-n9wrp Total loading time: 0 Render date: 2024-07-17T12:45:57.389Z Has data issue: false hasContentIssue false
  • English
  • Français

Coronite and eclogite formation in olivine gabbro (Western Norway): reaction paths and garnet zoning

Published online by Cambridge University Press:  05 July 2018

Mai Britt E. Mørk
Mai Britt E. Mørk*
Affiliation:
Mineralogisk Geologisk Museum, Sars gate 1, Oslo 5, Norway
Get access Rights & Permissions [Opens in a new window]

Abstract

Gabbros and dolerites in the Western Gneiss Region of Norway have been subjected to a high P-T regime and preserve evidence of the existence of several stages in the consequent reaction sequence. Incomplete reaction stages are characterized by corona structures between relict igneous phases and by frequent pseudo-morphs after igneous olivine, plagioclase and augite. The increasing degree of reaction is recorded by successive increases of modal garnet, omphacite and phlogopite (±orthopyroxene) to produce eclogite, often with excellent pseudomorphic preservation of the igneous fabric.

Pseudomorphic replacement of olivine by orthopyroxene (in coronas and aggregates) and of plagioclase by local assemblages of garnet, spinel, and sodic plagioclase, is interpreted as a transient reaction stage with restricted and selective diffusion between the original mafic and felsic domains. Complete eclogitization is compatible with more extensive diffusion, especially of Na and Al (on a mm scale) leading to omphacite production by replacement of olivine, augite, and orthopyroxene. Concomitant reactions in the felsic domains lead to total replacement of the transient phases by garnet, with or without inclusions of minute omphacite grains.

Strong Ca zoning of garnet in the coronites is inter-preted as a relict growth zoning, attributed to local controls by diffusion and subreactions in the plagioclase host and to local garnet + plagioclase + spinel equilibria. In contrast, complete eclogitization is associated with diffusional homogenization of garnet by (Mg, Fe)Ca−1 and MgFe−1 exchange with omphacite ± phlogopite.

Keywords

coroniteseclogitesgarnet zoninggabbroNorway
Type
Rates of Metamorphic Reactions
Information
Mineralogical Magazine , Volume 50 , Issue 357 , September 1986 , pp. 417 - 426
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1986

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.)

Footnotes

*

Present address: Institute of Biology and Geology, University of Tromsø, 9000 Tromsø, Norway.

References

Ahrens, T.J., and Shubert, G. (1975) Earth Planet. Sci. Lett. 27, 90-4.CrossRefGoogle Scholar
Austrheim, H., and Griffin, W.L. (1985) Chem. Geol. 50, 267-81.CrossRefGoogle Scholar
Austrheim, H., and Griffin, W.L. and Robins, B. (1981) Lithos. 14, 275-81.CrossRefGoogle Scholar
Brady, J.B. (1983) Am. J. Sc. 283-A, 181–200.Google Scholar
Brodie, K.H., and Rutter, E.H. (1985) In Advances in Physical Geochemistry, 4. Metamorphic reactions: kinetics, textures and deformatio.(A. B. Thompson and D. Rubie, eds.). Springer-Verlag, pp. 138-79.CrossRefGoogle Scholar
Dowty, E. (1980) Am. Mineral. 65, 174-82.Google Scholar
Emmett, T.F. (1982) Mineral. Mag. 46, 43-8.CrossRefGoogle Scholar
Esbensen, K.H. (1978) Neues Jahrb. Mineral. Abh. 132, 113-35.Google Scholar
Gasparic, T., and Lindsley, D.H. (1980) In Reviews in mineralogy, 7. Pyroxenes(C. T. Prewitt, ed.). Mineral. Soc. Am., pp. 309-39.Google Scholar
Ghent, E.D. (1976) Am. Mineral. 61, 710-14.Google Scholar
Gjelsvik, T. (1952) Norsk Geol. Tidsskr. 30, 33-134.Google Scholar
Griffin, W.L., and Brueckner, H.K. (1980) Nature. 285, 319-21.CrossRefGoogle Scholar
Griffin, W.L., and Brueckner, H.K. and Heier, K.S. (1973) Lithos. 6, 315-35.CrossRefGoogle Scholar
Griffin, W.L., and Brueckner, H.K. and Raheim, A. (1973) Ibid. 6, 21-40.Google Scholar
Herzberg, C.T. (1978) Geochim. Cosmochim. Acta. 42, 945-57.CrossRefGoogle Scholar
Krogh, E.J. (1982) Lithos. 15, 305-21.CrossRefGoogle Scholar
McConnell, J.D.C. (1975) Ann. Rev. Earth Planet. Sci. 3, 129-55.CrossRefGoogle Scholar
McLelland, J.M., and Whitney, P.R. (1980) Contrib. Mineral. Petrol. 72, 111-22.CrossRefGoogle Scholar
Mearns, E.W. (1984) Unpubl. Ph.D. thesis, Univ. Aberdeen.Google Scholar
Mongkoltip, P., and Ashworth, J.R. (1983) J. Petro. 24, 635-65.CrossRefGoogle Scholar
Mork, M.B.E. (1985a) Chem. Geol. 50, 283-310.CrossRefGoogle Scholar
Mork, M.B.E. (1985ft) . Metamorphic Geol. 3, 245-64.CrossRefGoogle Scholar
Mork, M.B.E. and Mearns, E.W. (1986) Lithos,in press.Google Scholar
Nishiyama, T. (1983) Geochim. Cosmochim. Acta. 47, 283-94.CrossRefGoogle Scholar
Obata, M. (1976) Am. Mineral. 61, 804-16.Google Scholar
Spear, F.S., and Selverstone, J. (1983) Contrib. Mineral. Petrol. 83, 348-57.CrossRefGoogle Scholar
Thompson, A.B., Tracy, R.J., Lyttle, P.T., and Thompson, J.B. (1977) Am. J. Sci. 277, 1152-67.CrossRefGoogle Scholar
Torudbakken, B.O. (1982) Unpubl. Cand. Real, thesis. Univ. Oslo.Google Scholar
Tracy, R.J. (1982) In Characterization of metamorphism through mineral equilibria. Reviews in mineralogy,10 (J. M. Ferry, ed.). Mineral. Soc. Am., 397 pp.Google Scholar
Robinson, P., and Thompson, A.B. (1976) Am. Mineral. 61, 762-75.Google Scholar
van Lamoen, H. (1979) Contrib. Mineral. Petrol. 68, 259-68.CrossRefGoogle Scholar
Wood, B.J. (1974) Ibid. 46, 1-15.Google Scholar