Hostname: page-component-cd9895bd7-fscjk Total loading time: 0 Render date: 2024-12-23T18:18:42.319Z Has data issue: false hasContentIssue false
  • English
  • Français

‘Decompressional’ reaction textures formed by isobaric heating: an example from the thermal aureole of the Taylor Brook Gabbro Complex, western Newfoundland

Published online by Cambridge University Press:  05 July 2018

S. J. Ings  and
J. V. Owen
S. J. Ings
Affiliation:
Department of Geology, Saint Mary's University, Halifax, Nova Scotia, Canada B3H 3C3
J. V. Owen*
Affiliation:
Department of Geology, Saint Mary's University, Halifax, Nova Scotia, Canada B3H 3C3
*
*E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Reaction textures including corona structures in granulites from the Proterozoic Long Range Inlier of western Newfoundland are spatially associated with a Silurian (0.34 Ga) mafic intrusion, the Taylor Brook Gabbro Complex. They comprise, in metabasites and tonalitic gneiss, coronal orthopyroxene and plagioclase on garnet and, in metapelites, cordierite and spinel formed at the expense of sillimanite, garnet and quartz. Although generally interpreted to indicate near-isothermal decompression (ITD) following regional metamorphism, which in the inlier occurred at ˜1.10–1.03 Ga, these features appear to be absent elsewhere. Therefore they are interpreted to be products of contact metamorphism (near-isobaric heating – IBH) within the thermal aureole of the gabbro. Thus, there is a ˜0.7 Ga difference (i.e. mid-Proterozoic vs. mid-Silurian) between the age of the regional metamorphic mineral assemblages and the contact aureole assemblages. The observation that classic ITD features occur in this aureole environment underscores the fact that P-sensitive reactions can progress during IBH as well as by pressure release.

Keywords

coronaNewfoundlandCanadaTaylor Brook Gabbro Complexisothermal decompressionisobaric heating
Type
Research Article
Information
Mineralogical Magazine , Volume 66 , Issue 6 , December 2002 , pp. 941 - 951
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2002

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

Berman, R.G. (1988) Internally-consistent thermodynamic data for minerals in the system Na2O-K2O-CaO-MgO-FeO-Fe2O3-Al2O3-SiO2-TiO2-H2O-CO2 . Journal of Petrology, 29, 445–522.CrossRefGoogle Scholar
Berman, R.G. (1990) Mixing properties of Ca-Mg-Fe-Mn garnets. American Mineralogist, 75, 328–344.Google Scholar
Berman, R.G. (1991) Thermobarometry using multi-equilibrium calculations: a new technique with petrologic applications. The Canadian Mineralogist, 29, 833–855.Google Scholar
Berman, R.G. and Koziol, A.M. (1991) Ternary excess properties of grossular-pyrope almandine garnets and their influence in geothermobarometry. American Mineralogist, 76, 1223–1231.Google Scholar
Bohlen, S.R. (1991) On the formation of granulites. Journal of Metamorphic Geology, 9, 223–229.CrossRefGoogle Scholar
Brown, M. (2002) Retrograde processes in migmatites and granulites revisited. Journal of Metamorphic Geology, 20, 25–40.CrossRefGoogle Scholar
Cooke, R.A., O'Brien, P.T. and Carswell, D.A. (2000) Garnet zoning and the identification of equilibrium mineral compositions in high-pressure-temperature granulites from the Moldanubian Zone, Austria. Journal of Metamorphic Geology, 18, 551–569.CrossRefGoogle Scholar
Ellis, D.J. (1980) Osumilite-sapphirine-quartz granulites from Enderby Land, Antarctica: pressure-temperature conditions of metamorphism, implications for garnet-cordierite equilibria and the evolution of the deep crust. Contributions to Mineralogy and Petrology, 74, 201–210.CrossRefGoogle Scholar
Frost, B.R. and Chacko, T. (1989) The granulite uncertainty principle: Limitations on thermobarometry in granulites. Journal of Geology, 97, 435–450.CrossRefGoogle Scholar
Fuhrman, M.L. and Lindsley, D.H. (1988) Ternary-feldspar modeling and thermometry. American Mineralogist, 73, 201–216.Google Scholar
Harley, S.L. (1989) The origins of granulites: a metamorphic perspective. Geological Magazine, 126, 215–247.CrossRefGoogle Scholar
Heaman, L.M, Erdmer, P. and Owen, J.V. (2002) U-Pb geochronologic constraints on the crustal evolution of the Long Range Inlier, Newfoundland. Canadian Journal of Earth Sciences, 39, 845–865.CrossRefGoogle Scholar
Jamieson, R.A. (1991) P-T-t paths of collisional orogens. Geologische Rundschau, 80/2, 321–332.CrossRefGoogle Scholar
Jones, K.A. and Escher, J.C. (2002) Near-isothermal decompression within a clockwise P-T evolution recorded in migmatitic mafic granulites from Clavering Ø, NE Greenland: implications for the evolution of the Caledonides. Journal of Metamorphic Geology, 20, 365–378.CrossRefGoogle Scholar
Kretz, R. (1983) Symbols for rock-forming minerals. American Mineralogist, 68, 277–279.Google Scholar
Mengel, F. and Rivers, T. (1991) Decompression reactions and P-T conditions in high-grade rocks, northern Labrador: P-T-t paths from individual samples and implications for early Proterozoic tectonic evolution. Journal of Petrology, 32, 139–167.CrossRefGoogle Scholar
Newton, R.C. (1983) Geobarometry of high-grade metamorphic rocks. American Journal of Science, 283-A, 1–28.Google Scholar
Owen, J.V. (1991 a) Geology of the Long Range Inlier, Newfoundland. Geological Survey of Canada Bulletin, 395, 15–18, 57–59.Google Scholar
Owen, J.V. (1991 b) Cordierite + spinel parageneses in pelitic gneiss from the contact aureoles of the Mistastin batholith (Quebec) and the Taylor Brook gabbro complex (Newfoundland). Canadian Journal of Earth Science, 28, 372–381.CrossRefGoogle Scholar
Owen, J.V. and Dostal, J. (1996) Contrasting corona structures in mafic granulite from the Blansky les complex, Bohemian massif, Czech Republic. The Canadian Mineralogist, 34, 959–966.Google Scholar
Owen, J.V. and Erdmer, P. (1989) Metamorphic geology and regional geothermobarometry of a Grenvillian massif: the Long Range Inlier, Newfoundland. Precambrian Research, 43, 79–100.CrossRefGoogle Scholar
Owen, J.V. and Greenough, J.D. (1994) Influence of the mode and distribution of garnet and biotite on Grt-Bt thermometry: evidence from a single-sample case study. Mineralogical Magazine, 59, 497–504.CrossRefGoogle Scholar
St.-Onge, M.R. and Ijewliw, O.J. (1996) Mineral corona formation during high-P retrogression of granulitic rocks, Ungava Orogen, Canada. Journal of Petrology, 37, 553–582.CrossRefGoogle Scholar
Warren, R.G. and Stewart, A.J. (1988) Isobaric cooling of Proterozoic high-temperature metapelites in the northern Arunta Block, central Australia: implications for tectonic evolution. Precambrian Research, 41, 175–198.CrossRefGoogle Scholar
Zhao, G.C., Wilde, S.A., Cawood, P.A. and Lu, L.Z. (2000) Petrology and P-T path of the Fuping mafic granulites: implications for tectonic evolution of the central zone of the North China craton. Journal of Metamorphic Geology, 18, 375–391.CrossRefGoogle Scholar