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Melt segregation and magma flow in migmatites: implications for the generation of granite magmas

  • E. W. Sawyer (a1)

To form a granite pluton, the felsic melt produced by partial melting of the middle and lower continental crust must separate from its source and residuum. This can happen in three ways: (1) simple melt segregation, where only the melt fraction moves; (2) magma mobility, in which all the melt and residuum move together; and (3) magma mobility with melt segregation, in which the melt and residuum move together as a magma, but become separated during flow. The first mechanism applies to metatexite migmatites and the other two to diatexite migmatites, but the primary driving forces for each are deviatoric stresses related to regional-scale deformation. Neither of the first two mechanisms generates parental granite magmas. In the first mechanism segregation is so effective that the resulting magmas are too depleted in FeOT, MgO, Rb, Zr, Th and the REEs, and in the second no segregation occurs. Only the third mechanism produces magmas with compositions comparable with parental granites, and occurs at a large enough scale in the highest grade parts of migmatite terranes, to be considered representative of the segregation processes occurring in the source regions of granites.

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Albuquerque, C. A. R. 1971. Petrochemistry of a series of granitic rocks from Northern Portugal. GEOL SOC AM BULL 82, 2783–98.
Alburquerque, C. A. R. 1978. Rare earth elements in ‘younger’ granites, northern Portugal. LITHOS 11, 219–29.
Arth, A. G.&Hanson, G. N. 1975. Geochemistry and origin of the early Precambrian crust of northeastern Minnesota. GEOCHIM COSMOCHIM ACTA 39, 197241.
Arzi, A. A. 1978. Critical phenomena in the rheology of partly melted rocks. TECTONOPHYSICS 44, 173–84.
Bagby, W. G, Cameron, K. L.&Cameron, M. 1981. Contrasting evolution of calc-alkali volcanic and plutonic rocks of western Chihuahua, Mexico. J GEOPHYS RES 86, 10, 402–10.
Bagnold, R. A. 1956. The flow of cohesionless grains in a fluid. PHIL TRANS R SOC LONDON A249, 235–97.
Barbey, P., Bertrand, J. M., Angoua, S.&Dautel, D. 1989. Petrology and U/Pb geochronology of the Telohat migmatites, Aleksod. Central Hoggar, Algeria. CONTRIB MINERAL PETROL 101, 207–19.
Barker, F., Arth, J. G.&Stern, T. W. 1986. Evolution of the Coast batholith along the Skagway Traverse, Alaska and British Columbia. AM MINERAL 71, 632643.
Barker, F., Farmer, G. L., Ayuso, R. A., Plafker, G.&Lull, J. S. 1992. The 50 Ma granodiorite of the eastern Gulf of Alaska: melting in an accretionary prism in the forearc. J GEOPHYS RES 97, 6757–78.
Bickfotd, M. E., Sides, J. R.&Cullers, R. L. 1981. Chemical evolution of magmas in the Proterozoic terrane of the St. Francois mountains, southeastern Missouri 1. Field, petrographic and major element data. J GEOPHYS RES 86, 10, 365–86.
Breaks, F. W., Bond, W. D.&Stone, D. 1978. Preliminary geological synthesis of the English River Subprovince, northwestern Ontario and its bearing upon mineral exploration. ONTARIO GEOL SURV MISC PAP 72,
Brouand, M., Banzet, G.&Barbey, P. 1990. Zircon behaviour during crustal anatexis. Evidence from the Tibetan Slab migmatites (Nepal). J VOLCANOL GEOTHERM RES 44, 143–61.
Brown, M. 1973. Definition of metatexis, diatexis and migmatite. PROC GEOL ASSOC 84, 371382.
Brown, M. 1979. The petrogenesis of the St. Malo Migmatite Belt, Armorican Massif, France, with particular reference to the diatexites. N JAHRB MINERAL ABH 135, 4874.
Brown, M. 1994. The generation, segregation, ascent and emplacement of granite magma: The migmatite-to-crustally-derived granite connection in thickened orogens. EARTH-SCI REV 36, 83130.
Brown, M., Averkin, Y. A., McLellan, E. L.&Sawyer, E. W. 1995. Melt segregation in migmatites. J GEOPHYS RES 100, 15, 655–79.
Calvert, A. J., Sawyer, E. W., Davis, W. J.&Ludden, J. N. 1995. Archaean subduction inferred from seismic images of a mantle suture in the Superior Province, NATURE 375, 670–4.
Castelli, D.&Lombardo, B. 1988. The Gophu La and western Lunana granites: Miocene muscovite leucogranites of the Bhutan Himalaya. LITHOS 21, 211–25.
Chappell, B. W.&White, A. J. R. 1992. I- and S-type granites in the Lachlan Fold Belt. TRANS R SOC EDINBURGH EARTH SCI 83, 126.
Clemens, J. D.&Mawer, C. K. 1992. Granitic magma transport by fracture propagation. TECTONOPHYSICS 204, 339–60.
Collins, W. J.&Sawyer, E. W. Pervasive magma transfer through the lower-middle crust during non-coaxial compressional deformation: an alternative to dyking. J METAMORPH GEOL, in press.
Collins, W. J., Flood, R. H., Vernon, R. H.&Shaw, S. E. 1989. The Wuluma granite, Arunta Block, central Australia: an example of in situ, near-isochemical granite formation in a granulite facies terrane. LITHOS 23, 6383.
Crawford, M. B.&Windley, B. F. 1990. Leucogranites of the Himalaya/Karakoram: implications for magmatic evolution within collisional belts and the study of collision related leucogranite genesis. J VOLCANOL GEOTHERM RES 44, 119.
Crisci, G. M., Maccarrone, E.&Rottura, A. 1979. Cittanova peraluminous granites (Calabri, southern Italy). MINER PETROGR ACTA 23, 279302.
Currie, K. L.&Pajari, G. E. 1981. Anatectic peraluminous granites from the Carmanville area, northeastern Newfoundland. CAN MINERAL 19, 147–62.
Daines, M. J.&Richter, F. M. 1988. An experimental method for directly determining the interconnectivity of melt in a partially molten system. GEOPHYS RES LETT 15, 1459–62.
Day, W. C.&Weblen, P. W. 1986. Origin of Late Archaean granite: geochemical evidence from the Vermilion Granite Complex of northern Minnesota. CONTRIB MINERAL PETROL 93, 283–96.
Dell'Angelo, L. N.&Tullis, J. 1988. Experimental deformation of partially melted granitic aggregates. J METAMORPH GEOL 6, 495516.
D'Lemos, R. S., Brown, M.&Strachan, R. A. 1992. The relationship between granite and shear zones: magma generation, ascent and emplacement within a transpressional orogen. J GEOL SOC LONDON 149, 487–90.
Fershtater, G. B. 1977. Isochemical migmatization and genesis of quartzofeldspathic rocks of the Taratash metamorphic complex (southern Urals). GEOCHEM INT 14, 6372.
Gupta, L. N.&Johannes, W. 1982. Petrogenesis of a stromatic migmatite (Nelaug, southern Norway). J PETROL 23, 548–67.
Gupta, L. N.&Johannes, W. 1985. Effect of metamorphism and partial melting of host rocks on zircons. J METAMORPH GEOL 3, 311–23.
Henkes, L.&Johannes, W. 1981. The petrology of a migmatite (Arvika, Varmland, western Sweden). N JARHB MINERAL ABH 141, 113–33.
Jensen, I. S. 1985. Geochemistry of the central granitic stock in the Glitrevann cauldron within the Oslo Rift, Norway. NORSK GEOL TIDSSKR 65, 201–16.
Lapointe, B.&Chown, E. H. 1993. Gold-bearing iron-formation in a granulite terrane of the Canadian Shield: a possible deep-level expression of an Archean gold-mineralizing system. MINERAL DEPOSITA 28, 191–7.
Le Breton, N.&Thompson, A. B. 1988. Fluid-absent (dehydration) melting of biotite in metapelites in the early stages of crustal anatexis. CONTRIB MINERAL PETROL 99, 226–37.
Maaløe, S. 1982. Geochemical aspects of permeability controlled partial melting and fractional crystallization. GEOCHIM COSMOCHIM ACTA 46, 4357.
Martin, H. 1980. Comportement de quelques elements en traces au cours de l'anatexie. L'exemple du massif de Saint Malo (Bretagne, France). CAN J EARTH SCI 17, 927–41.
McCarthy, T. S.&Groves, D. I. 1979. The Blue Tier Batholith, Northeastern Tasmania. CONTRIB MINERAL PETROL 71, 193209.
McKenzie, D. 1985. The extraction of magma from the crust and mantle. EARTH PLANET SCI LETT 74, 8191.
McKenzie, C. B. & Clarke D. B. 1975. Petrology of the South Mountain Batholith, Nova Scotia. CAN J EARTH SCI 12, 1209–18.
Mehnert, K. R.&Büsch, W. 1982. The initial stage of migmatite formation. N JARHB MINERAL ABH 145, 211–38.
Nédélec, A., Minyem, D.&Barbey, P. 1993. High–P–high–T anatexis of Archaean tonalitic grey gneisses: the Eseka migmatites, Cameroon. PRECAMBRIAN RES 62, 191205.
Neiva, A. M. R. 1981. Geochemistry of hybrid granitoid rocks and their biotites from central northern Portugal and their petrogenesis. LITHOS 14, 149–63.
Nicolas, A., Freydier, Cl., Godard, M.&Vauchez, A. 1993. Magma chambers at oceanic ridges; how large? GEOLOGY 21, 53–6.
Norman, M. D., Leeman, W. P.&Mertzman, S. A. 1992. Granites and rhyolites from the northwestern U.S.A.: temporal variation in magmatic processes and relations to tectonic setting. TRANS R SOC EDINBURGH EARTH SCI 83, 7181.
Obata, M., Yoshimura, Y., Nagakawa, K., Odawara, S.&Osanai, Y. 1994. Crustal anatexis and melt migrations in the Higo metamorphic terrane, west-central Kyushu, Kumamoto, Japan. LITHOS 32, 135–47.
Pearce, J. A., Harris, N. B. W.&Tindle, A. G. 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. J PETROL 25, 956–83.
Percival, J. A. 1990. Archean tectonic setting of granulite terranes of the Superior Province, Canada: a view from the bottom. In Vielzeuf, D.&Vidal, Ph. (eds) Granulites and crustal evolution, 171193. Amsterdam: Kluwer.
Percival, J. A. 1991. Granulite-facies metamorphism and crustal magmatism in the Ashuanipi Complex, Quebec–Labrador, Canada. J PETROL 32, 1261–97.
Percival, J. A., Card, K. D., Stern, R. A.&Begin, N. J. 1990. A geological transect of northeastern Superior Province, Ungava Peninsula, Quebec: the Lake Minto area. CURR RES PART C GEOL SURV CAN 90–1c, 133–41.
Petford, N., Kerr, R. C.&Lister, J. R. 1993. Dike transport of granitoid magmas, GEOLOGY 21, 845–8.
Poli, G., Ghezzo, C.&Conticelli, S. 1989. Geochemistry of granitic rocks from the Hercynian Sardinia–Corsica batholith: implication for magma genesis. LITHOS 23, 247–66.
Read, H. H. 1957. The granite controversy. London: Murby.
Reid, J. B., Evans, O. C.&Fates, D. G. 1983. Magma mixing in granitic rocks of the central Sierra Nevada, California. EARTH PLANET SCI LETT 66, 243–61.
Rutter, E. H.&Neumann, D. H. K. 1995. Experimental deformation study of partly molten Westerly granite under fluid-absent conditions, with implications for the extraction of granitic magmas. J GEOPHYS RES 100, 15, 697716.
Saavedra, J., Rossi de Toselli, J., Toselli, A.&Garcia-Sanchez, A. 1985. The origin of the two-mica granites of the Loma Pelada pluton. Tucuman, northwest Argentina. LITHOS 18, 179–85.
Sawyer, E. W. 1987. The role of partial melting and fractional crystallization in determining discordant migmatite leucosome compositions. J PETROL 28, 445–73.
Sawyer, E. W. 1991. Disequilibrium melting and the rate of meltresiduum separation during migmatisation of mafic rocks from the Grenville Front, Quebec. J PETROL 32, 701–38.
Sawyer, E. W. 1994. Melt segregation in the continental crust. GEOLOGY 22, 1019–22.
Sawyer, E. W.&Barnes, S.-J. 1988. Temporal and compositional differences between subsolidus and anatectic migmatite leucosomes from the Quetico metasedimentary belt, Canada. J METAMORPH GEOL 6, 437–50.
Sawyer, E. W.&Benn, K. 1993. Structure of the high-grade Opatica Belt and adjacent low-grade Abitibi Subprovince, Canada: an Archaean mountain front. J STRUCT GEOL 15, 1443–58.
Stevens, G.&Clemens, J. D. 1993. Fluid-absent melting and the roles of fluids in the lithosphere: a slanted summary? CHEM GEOL 108, 117.
Stormgard, K. E. 1973. Stress distribution during the formation of boudinage and pressure shadows. TECTONOPHYSICS 16, 215–48.
Torres-Roldan, R. L. 1983. Fractionated melting of metapelite and further crystal-melt equilibria—the example of the Blanca Unit migmatite complex, north of Estepona (southern Spain). TECTONOPHYSICS 96, 95123.
Vielzeuf, D.&Holloway, J. R. 1988. Experimental determination of the fluid-absent melting relations in the pelitic system: consequences for crustal differentiation. CONTRIB MINERAL PETROL 98, 257–76.
Vigneresse, J. L., Cuney, M.&Barbey, P. 1991. Deformation assisted crustal melt segregation and transfer. GAC-MAC ABSTR 16, A128.
Wall, V. J., Clemens, J. D.&Clarke, D. B. 1987. Models for granitoid evolution and source compositions. J GEOL 95, 731–49.
Weaver, S. D., Adams, C. J., Pankhurst, R. J.&Gibson, I. L. 1992. Granites of Edward VII Peninsular, Marie Byrd Land: anorogenic magmatism related to Antarctic-New Zealand rifting. TRANS R SOC EDINBURGH EARTH SCI 83, 281–90.
Weber, C, Barbey, P., Cuney, M.&Martin, H. 1985. Trace element behaviour during migmatization: evidence for a complex melt—residuum—fluid interaction in the St. Malo migmatitic dome (France). CONTRIB MINERAL PETROL 90, 5262.
White, A. J. R. 1966. Genesis of migmatites from the Palmer region of South Australia. CHEM GEOL 1, 165200.
White, A. J. R.&Chappell, B. W. 1977. Ultrametamorphism and granitoid genesis. TECTONOPHYSICS 43, 722.
White, A. J. R.&Chappell, B. W. 1990. Per migma ad magma downunder. GEOL J 25, 221–5.
Whitney, D. L.&Irving, A. J. 1994. Origin of K-poor leucosomes in a metasedimentary migmatite complex by ultrametamorphism, syn-metamorphic magmatism and subsolidus processes. LITHOS 32, 173–92.
Wickham, S. M. 1987a. The segregation and emplacement of granitic melts. J GEOL SOC LONDON 144, 281–97.
Wickham, S. M. 1987b. Crustal anatexis and granite petrogenesis during low-pressure regional metamorphism: the Trois Seigneurs Massif, Pyrenees, France. J PETROL 28, 127–69.
Winkler, H. G. F.&von Platten, H. 1961. Experimentelle Gesteinsmetamorphose—V. GEOCHIM COSMOCHIM ACTA 24, 250–9.
Williams, M. L., Hanmer, S., Kopf, C.&Darrach, M. 1995. Syntectonic generation and segregation of tonalitic melts from amphibolite dykes in the lower crust Striding–Athabasca mylonite zone, northern Saskatchewan. J GEOPHYS RES 100, 15 717–34.
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