Abstract
Subsolidus and melting reactions involving calcic plagioclase in pelitic assemblages in the K-Na-Ca model system occur at higher temperatures than their K-Na counterparts. For the most calcic plagioclase compositions observed in high-grade pelitic rocks (An25-An40) the equilibria are rarely extended by more than 30 ° C above those in KA1O2-NaAlO2-Al2O3-SiO2-H2O, although all discontinuities in facies inferred for the K-Na system are continuously displaced when they involve Ca-bearing plagioclase. The maximum pressure-temperature overlap between muscovite dehydration and initial melting reactions occurs in the pressure range of 4–6 kbar between about 640 ° and 720 ° C. This provides optimum conditions for anatectic melt generation in felsic rocks of the appropriate compositions progressively metamorphosed in kyanite-sillimanite facies series. Progressive regional metamorphism at pressures of 2–4 kbar, corresponding to andalusite-sillimanite facies series, shows little overlap between muscovite dehydration and initial melting reactions. Consequently anatectic melt generation in andalusite-sillimanite facies series would require the participation of biotite in dehydration-melting reactions. Felsic intrusive rock in andalusite-sillimanite terranes could have risen upward from their anatectic sites in high grade kyanite-sillimanite facies series at depth. Many andalusite-sillimanite facies series terranes culminating in migmatites could represent upward movement of kyanite-sillimanite facies series rocks to shallower depths with uplift rates faster than cooling rates.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Abbott, R.N., Jr.: Peritectic reactions in the system An-Ab-Or-Qz-H2O. Can. Mineral. 16, 245–256 (1978)
Boettcher, A.L.: The system CaO-Al2O3-SiO2-H2O at high pressures and temperatures. J. Petrol. 11, Part 2, 337–379 (1970)
Brown, G.C., Fyfe, W.S.: The production of granitic melts during. ultrametamorphism. Contrib. Mineral. Petrol. 28, 310–318 (1970)
Chatterjee, N.D.: Margarite stability and compatibility relations in the system CaO-A12O3-SiO2H2O as a pressure-temperature indicator. Am. Mineral. 61, 699–709 (1976)
Chatterjee, N.D., Froese, E.: A thermodynamic study of the pseudobinary join muscovite-paragonite in the system KAlSi3O8-NaAlSi3O8-Al2O3-SiO2-H2O. Am. Mineral. 60, 985–993 (1975)
Chatterjee, N.D., Johannes, W.S.: Thermal stability and standard thermodynamic properties of synthetic 2M 1-muscovite, KAl2AlSi3O10(OH)2. Contrib. Mineral. Petrol. 48, 89–114 (1974)
England, P.C., Richardson, S.W.: The influence of erosion upon the mineral facies of rocks from different metamorphic environments. J. Geol. Soc. 134, 201–213 (1977)
Evans, B.W., Guidotti, C.V.: The sillimanite-potash feldspar isograd in western Maine, U.S.A. Contrib. Mineral. Petrol. 12, 25–62 (1966)
Guidotti, C.V.: Metamorphism of the pelitic schists in the Bryant Pond quadrangle, Maine. Am. Mineral. 48, 772–791 (1963)
Harris, N.B.W.: Some migmatite types and their origins, from the Barousse Massif, Central Pyrenees. Geol. Mag. 111 (4), 319–328 (1974)
Harris, P.G., Kennedy, W.Q., Scarfe, CM.: Volcanism versus plutonism The effect of Chemical Composition. In: Mechanics of Igneous Intrusion (G. Newall, N. Rast, eds.), pp. 187–200. Geol. J. Spec. Issue No. 2. Liverpool: Gallery Press 1970
Johannes, W., Orville, P.M.: Zur Stabilität der Mineralparagenesen Muskovit + Calcit + Quarz, Zoisit + Muskovit + Quarz, Anorthit + K-Feldspat und Anorthtit + Calcit. Fortschr. Mineral. 50, 47 (1972)
Kerrick, D.M.: Experimental determination of muscovite + quartz stability with \(P_{{\text{H}}_{\text{2}} {\text{O}}}\) < P total. Am. J. Sci. 272, 946–958 (1972)
Lundgren, L.W.: Muscovite reactions and partial melting in southeastern Connecticut. J. Petrol. 7, 421–453 (1966)
Robinson, P., ms: Gneiss domes of the Orange area, Massachusetts and New Hampshire. 253 p. Cambridge, MA, Harvard University Ph. D. Thesis 1963
Thompson, A.B.: Calculation of muscovite-paragonite-alkali feldspar phase relations. Contrib. Mineral. Petrol. 44, 173–194 (1974a)
Thompson, A.B.: The stability of feldspar in metamorphism. In: The feldspars (W.S. MacKenzie, J. Zussman, eds.), pp. 645–672. Manchester: Manchester University Press 1974b
Thompson, A.B., Algor, J.R.: Model systems for anatexis of pelitic rocks. I. Theory of melting reactions in the system KA1O2-NaAlO2-Al2O3-SiO2-H2O. Contrib. Mineral. Petrol. 63, 247–269 (1977)
Thompson, A.B., Lyttle, P.T., Thompson, J.B. Jr.: Mineral reactions and A-Na-K and A-F-M facies types in the Gassetts Schist, Vermont. Am. J. Sci. 277, 1124–1151 (1977)
Thompson, J.B., Jr.: Phengitic dioctahedral micas in metamorphosed pelites. Am. Geophys. Un. Prog. Spring Mtg., abstract V67A, p. 39 (1977)
Thompson, J.B., Thompson, A.B.: A model system for mineral facies in pelitic schists. Contrib. Mineral. Petrol. 58, 243–277 (1976)
Tracy, R.J.: High grade metamorphic reactions and partial melting in pelitic schist, West-Central Massachusetts. Am. J. Sci. 278, 150–178 (1978)
Winkler, H.G.F.: Viel Basalt und wenig Gabbro-wenig Rhyolith und viel Granit. Beitr. Mineral. Petrogr. 8, 222–231 (1962)
Winkler, H.G.F.: Petrogenesis of metamorphic rocks. 4th edn., 334p. Berlin, Heidelberg, New York: Springer 1976
Wyllie, P.J.: Crustal anatexis: An experimental review. Tectonophysics 43, 41–71 (1977)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Thompson, A.B., Tracy, R.J. Model systems for anatexis of pelitic rocks. Contr. Mineral. and Petrol. 70, 429–438 (1979). https://doi.org/10.1007/BF00371049
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00371049