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Grain-scale and outcrop-scale distribution and movement of melt in a crystallising granite

Published online by Cambridge University Press:  03 November 2011

E. W. Sawyer
E. W. Sawyer*
Affiliation:
Sciences de la Terre, Département des Sciences Appliquées,Université du Québec à Chicoutimi, Chicoutimi, Québec G7H 2B1,Canada; e-mail: [email protected]
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Abstract

The distribution of melt has been mapped in a granite pluton deformed whilst it contained melt. At the outcrop scale, leucomonzogranite melt was segregated from hornblende monzogranite when the rigid crystal framework was tectonically compacted. The melt collected in well-defined, structurally controlled sites that formed during dextral, non-coaxial, strike-slip shearing. The segregations are generally isolated, but locally they link to form extensive branched arrays which drained larger volumes of granite in a two-step process. First, melt drained from the compacting matrix through the array and pooled along dilatant foliation planes; later, the melt moved farther away when a single planar melt-transfer channel formed.

Thin section maps show that most melt was distributed in the foliation plane and along the lineation in the crystallising matrix. The location of melt at the grain scale is primarily controlled by the feldspar-dominated shape fabric of the crystal framework, and not by tectonic stresses as at the outcrop scale. Tectonic stresses account for the relatively small proportion of melt films located in grain boundaries normal to the lineation. The distribution of melt-bearing grain boundaries outlines larger domains in the thin sections that form a linked three-dimensional network through which melt moved within the crystallising framework.

Keywords

grain boundariesmelt segregationtexture
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 91 , Issue 1-2: Fourth Hutton Symposium: The Origin of Granites and Related Rocks , 2000 , pp. 73 - 85
Copyright
Copyright © Royal Society of Edinburgh 2000

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References

Arsenault, L., Danis, D., Forbes, E., Gaudreau, R.& Perreault, S. 1994. Carte geotouristique de la Cote-Nord. Ministère des Ressources Naturelles, Carte GT94-01.Google Scholar
Avramtchev, L. 1985. Carte Géologique du Quebec. Ministère Energie Ressources Quebec, Carte 2000, DV84-02.Google Scholar
Barbey, P., Bertrand, J.-M., Angoua, S.& Dautel, D. 1989. Petrology and U/Pb geochronology of the Telohat migmatites, Aleksod, central Hoggar, Algeria. Contributions to Mineralogy and Petrology 101, 207–19.Google Scholar
Barbey, P., Macaudiere, J.& Nzenti, J.P. 1990. High-pressure dehydration melting of metapelites: Evidence from the migmatites of Yaounde (Cameroon). Journal of Petrology 31, 401–27.Google Scholar
Barbey, P., Brouand, M., Le Fort, P.& Pecher, A. 1996. Granite-migmatite genetic-link: example of the Manaslu granite and Tibetan slab migmatites in central Nepal. Lithos 38, 63–79.Google Scholar
Bell, T. H.& Hammond, R. L. 1984. On the internal geometry of mylonite zones. Journal of Geology 92, 667–86.Google Scholar
Blumenfeld, P.& Bouchez, J.-L. 1988. Shear criteria in granite and migmatite deformed in the magmatic and solid states. Journal of Structural Geology 10, 361–72.Google Scholar
Bouchez, J.-L., Delas, C., Gleizes, G., Nedelec, A.& Cuney, M. 1992. Submagmatic microfractures in granites. Geology 20, 35–8.Google Scholar
Brown, M. 1994. The generation, segregation, ascent and emplacement of granite magma: The migmatite-to-crustally-derived granite connection in thickened orogens. Earth-Science Review 36, 83–130.Google Scholar
Brown, M. Averkin, Y. A., McLellan, E.& Sawyer, E. W. 1995. Melt segregation in migmatites. Journal of Geophysical Research 100, 15,655–79.Google Scholar
Brown, M.& Rushmer, T. 1997. The role of deformation in the movement of granitic melt: Views from the laboratory and the field. In Holness, M. (ed.) Deformation-enhanced Melt Segregation and Metamorphic Fluid Transport, Mineralogical Society Series 8, 111–44. London, Chapman and Hall.Google Scholar
Brown, M.& Solar, G. 1998a. Granite ascent and emplacement during contractional deformation in convergent orogens. Journal of Structural Geology 20, 1365–93.Google Scholar
Brown, M.& Solar, G. 1998b. Shear zones and melts: positive feedback in orogenic belts. Journal of Structural Geology 20, 211–27.Google Scholar
Byron, D. N., Atherton, M. P.& Hunter, R. H. 1994. The description of the primary textures of ‘Cordilleran’ granitic rocks. Contributions to Mineralogy and Petrology 117, 66–75.Google Scholar
Chappell, B. W., White, A. J. R.& Wyborn, D. 1987. The importance of residual source material (restite) in granite petrogenesis. Journal of Petrology 28, 1111–38.Google Scholar
Clemens, J. D.& Mawer, C. K. 1992. Granitic magma transport by fracture propagation. Tectonophysics 204, 339–60.Google Scholar
Collins, W. J.& Sawyer, E. W. 1996. Pervasive granitoid magma transfer through the lower-middle crust during non-coaxial compressional deformation. Journal of Metamorphic Geology 14, 565–79.Google Scholar
Cuney, M. Friedrich, M., Blumenfeld, P., Bourguignon, A., Boiron, M. C., Vigneresse, J.-L.& Poty, B. 1990. Metallogenesis in the French part of the Variscan orogen. Part 1: U preconcentrations in the pre-Variscan and Variscan formations—a comparison with Sn, W and Au. Tectonophysics 177, 39–57.Google Scholar
Dickin, A. P.& Higgins, M. D. 1992. Sm/Nd evidence for a major 1.5 Ga crust-forming event in the central Grenville province. Geology 20, 137–40.Google Scholar
Gapais, D. 1989. Shear structures within deformed granites: mechanical and thermal indicators. Geology 17, 1144–7.Google Scholar
Gapais, D.& Barbarin, B. 1986. Quartz fabric transition in a cooling syntectonic granite (hermitage Massif, France). Tectonophysics 125, 357–70.Google Scholar
Hibbard, M. J. 1987. Deformation of incompletely crystallised magma systems: granitic gneisses and their implications. Journal of Geology 95, 543–61.Google Scholar
Higgins, M. D.& van Breeman, O. 1996. Three generations of anothosite–mangerite–charnockite–granite (AMCG) magmatism, contact metamorphism and tectonism in the Saguenay—Lac-Saint-Jean region of the Grenville Province, Canada. Precambrian Research 79, 327–46.Google Scholar
John, B. E.& Stunitz, H. 1997. Magmatic fracturing and small-scale melt segregation during pluton emplacement: evidence from the Adamello Massif (Italy). In Bouchez, J-.L., Hutton, D. H. W.& Stephens, W. E. (eds) Granite: From Segregation of Melt to Emplacement Fabrics, 55–74. Dordrecht: Kluwer.Google Scholar
Jurewicz, S. R.& Watson, E. B. 1985. The distribution of partial melt in a granitic system: the application of liquid phase sintering theory. Geochimica et Cosmochimica Acta 49, 1109–21.Google Scholar
Nicolas, A. 1992. Kinematics in magmatic rocks with special reference to gabbros. Journal of Petrology 33, 891–915.Google Scholar
Platt, J. P. 1984. Secondary cleavages in ductile shear zones. Journal of Structural Geology 6, 439–42.Google Scholar
Platt, J. P.& Vissers, R. L. M. 1980. Extensional structures in anisotropic rocks. Journal of Structural Geology 2, 397–410.Google Scholar
Pons, J., Barbey, P., Dupuis, D.& Leger, J. M. 1995. Mechanisms of pluton emplacement and structural evolution of 2.1 Ga juvenile continental crust: the Birimian of southwestern Niger. Precambrian Research 70, 281–301.Google Scholar
Rivers, T., Martignole, J., Gower, C. F.& Davidson, A. 1989. New tectonic divisions of the Grenville Province, southeastern Canadian Shield. Tectonics 8, 63–84.Google Scholar
Robin, P.-Y. F. 1979. Theory of metamorphic segregation and related processes. Geochimica et Cosmochimica Acta 43, 1587–1600.Google Scholar
Robin, P.-Y. F.& Cruden, A. R. 1994. Strain and vorticity in ideally ductile transpression zones. Journal of Structural Geology 16, 447–66.Google Scholar
Rosenberg, C. L.& Handy, M. R. 2000. Syntectonic melt pathways during simple shearing of an anatectic rock analogue (norcamphor-benzamide). Journal of Geophysical Research 105, 3135–3149.Google Scholar
Rosenberg, C. L.& Riller, U. 2000. Partial melt topology in statically and dynamically recrystallised granite. Geology 28, 7–10.Google Scholar
Rushmer, T. 1995. An experimental deformation study of partially molten amphibolite: application to low melt-fraction melt segregation. Journal of Geophysical Research 100, 15,681–96.Google Scholar
Rutter, E. H. 1997. The influence of deformation on the extraction of crustal melts: A consideration of the role of melt-assisted granular flow. In Holness, M. (ed.) Deformation-enhanced Melt Segregation and Metamorphic Fluid Transport, Mineralogical Society Series 8, 82–110. London, Chapman and Hall.Google Scholar
Rutter, E. H.& Neumann, D. 1995. Experimental deformation of partially molten Westerly granite under fluid-absent conditions with implications for the extraction of granitic magmas. Journal of Geophysical Research 100, 15,697–715.Google Scholar
Sawyer, E.W. 1987. The role of partial melting and fractional crystallisation in determining discordant migmatite leucosome compositions. Journal of Petrology 28, 445–73.Google Scholar
Sawyer, E. W. 1994. Melt segregation in the continental crust. Geology 22, 1019–22.Google Scholar
Sawyer, E. W. 1996. Melt segregation and magma flow in migmatites: implications for the generation of granite magmas. Transactions of the Royal Society of Edinburgh: Earth Sciences 87, 85–94.Google Scholar
Sawyer, E. W., Dombrowski, C.& Collins, W. J. 1999. Movement of melt during synchronous regional deformation and granulite-facies anatexis, an example from the Wuluma Hills, central Australia. In Castro, A., Fernandez, C.& Vigneresse, J.-L. (eds) Understanding Granites; Integrating New and Classical Techniques Geological Society of London Special Publication 158, 221–37.Google Scholar
Sawyer, E.W. (in press). Melt segregation in the continental crust: Distribution and movement of melt in anatectic rocks. Journal of Metamorphic Geology.Google Scholar
Thompson, A.B. 1996. Fertility of crustal rocks during anatexis. Transactions of the Royal Society of Edinburgh: Earth Sciences 87, 1–10.Google Scholar
van der Molen, I.& Paterson, M. S. 1979. Experimental deformation of partially-melted granite. Contributions to Mineralogy and Petrology 70, 299–318.Google Scholar
Vernon, R.H.& Collins, W.J. 1988. Igneous microstructures in migmatites. Geology 16, 1126–9.Google Scholar
Vigneresse, J.-L., Barbey, P.& Cuney, M. 1996. Rheological transitions during partial melting and crystallisation with application to felsic magma segregation and transfer. Journal of Petrology 37, 1597–600.Google Scholar
Vigneresse, J.-L.& Tikoff, B. 2000. Percolation thresholds and strain partitioning during partial melting and crystallising felsic magmas. Tectonophysics 312, 117–32.Google Scholar
Weinberg, R. F. 1999. Mesoscale pervasive felsic magma migration: alternatives to dyking. Lithos 46, 393–410.Google Scholar
White, A. J. R.& Chappell, B. W. 1977. Ultrametamorphism and granitoid genesis. Tectonophysics 43, 7–22.Google Scholar
Wickham, S. M. 1987. The segregation and emplacement of granitic magmas. Journal of the Geological Society of London 144, 281–97.Google Scholar
Williams, P. F.& Price, G. P. 1990. Origin of kinkbands and shear-band cleavage in shear zones: an experimental study. Journal of Structural Geology 12, 145–64.Google Scholar
Winkler, H. G. F. 1976. Petrogenesis of Metamorphic Rocks, 4th edn. New York: Springer.Google Scholar