Abstract
The new, greatly expanded internally-consistent dataset of Holland and Powell includes thermodynamic data for a wide range of mineral end-members in common rock-forming minerals, in particular, including FeMg-1 substitutions in glaucophane, garnet, chloritoid and carpholite, and FeMg-1 and MgSiAl-1Al-1 substitutions in talc and chlorite. Moreover, we have the uncertainties and correlations for these data. With the data, we have calculated the full pressure-temperature phase diagram for the system Na2O−FeO−MgO−Al2O3−SiO2−H2O (NFMASH) for quartz (or coesite) and H2O in excess, in the range 300°–800°C and 5–50 kbars. By solving the set of non-linear equations formed by the equilibrium relationships for an independent set of equations between the end-members in an assemblage in NFMASH, the compositions of the minerals (and PT) can be calculated. Thus the changes in MgSiAl-1Al-1 along NMASH reactions, and FeSiAl-1Al-1 along NFASH reactions, are calculated, and the changes in FeMg-1 and MgSiAl-1Al-1 along NFMASH reactions are calculated. From this information it is straightforward to generate PT diagrams for specific rock compositions. Mineral assemblages and mineral compositional changes in the phase diagram are discussed in relation to greenschist, blueschist and eclogite facies assemblages in metapelitic rocks. It is found that the correspondence between the predictions of the phase diagrams and the observations on rocks is remarkably good. When semiquantitative extensions of the phase diagram to include Ca(MgFe)-1, NaSiCa-1Al-1, Fe3+Al-1 and KNa-1 substitutions are taken into account the agreement is essentially complete.
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References
Brown EH, Forbes RB (1986) Phase petrology of eclogitic rocks in the Fairbanks district, Alaska. Geol Soc Am Mem 164:155–167
Chopin C (1981) Talc-phengite: a widespread assemblage in high-grade pelitic blueschists of the Western Alps. J Petrol 22:628–650
Chopin C (1984) Coesite and pure pyrope in high-grade blueschists of the Western Alps; a first record and some consequences. Contrib Mineral Petrol 86:107–118
Chopin C, Schreyer W (1983) Magnesio-carpholite and magnesiochloritoid: two index minerals of pelitic blueschists and their preliminary phase relations in the model system MgO−Al2O3−SiO2−H2O. Am J Sci 283A:72–96
Chopin C, Monié P (1984) A unique magnesiochloritoid-bearing, high-pressure assemblage from the Monte Rosa, Western Alps: petrologic and 40Ar39Ar radiometric study. Contrib Mineral Petrol 87:388–398
England PC (1987) Diffuse continental deformation: length scales, rates and metamorphic evolution. Phil Trans R Soc London A321:3–22
England PC, Richardson SW (1979) The influence of erosion upon the mineral facies of rocks from different metamorphic environments. J Geol Soc London 134:201–213
England PC, Thompson AB (1984) Pressure-temperature-time paths of regional metamorphism I, Heat transfer during the evolution of regions of thickened continental crust. J Petrol 24:894–928
Ghent ED, Stout MZ, Black PM, Brothers RN (1987) Chloritoid-bearing rocks associated with blueschists and eclogites, northern New Caledonia. J Metamorph Geol 5:239–254
Guiraud M, Burg JP, Powell R (1987) Evidence for a Variscan suture zone in the Vendee, France: a petrological study of blueschist facies rocks from Bois de Cene. J Metamorph Geol 5:225–237
Harte B, Hudson NFC (1979) Pelite facies series and the temperatures and pressures of Dalradian metamorphism in eastern Scotland. In: Harris AL, Holland CH, Leake BE (eds) The Caledonides of the British Isles reviewed. Geol Soc London Spec Pub 8:323–337
Hensen BJ (1971) Theoretical phase relations involving cordierite and garnet in the system FeO−MgO−Al2O3−SiO2. Contrib Mineral Petrol 31:191–214
Holland TJB (1979) High water activities in the generation of high pressure kyanite eclogites of the Tauern Window, Australia. J Geol 87:1–27
Holland TJB (1985) Preliminary phase relations involving glaucophane and applications to high pressure petrology: new heat capacity and thermodynamic data. Contrib Mineral Petrol 99:134–142
Holland TJB, Powell R (1988) An internally consistent dataset with uncertainties and correlations: 2. Data and results. J Metamorph Petrol 3:343–370
Holland TJB, Powell R (1990) An enlarged and updated internally consistent thermodynamic dataset with uncertainties and correlations: the system K2O−Na2O−CaO−MgO−MnO −FeO−Fe2O3−Al2O3−TiO2−SiO2−C−H2−O2. J Metamorph Geol (in press)
Holland TJB, Ray NJ (1985) Glaucophane and pyroxene breakdown reactions in the Pennine units of the eastern Alps. J Metamorph Geol 3:417–438
Koons PO (1986) Relative geobarometry from high-pressure rocks of quartzofeldspathic composition from the Sesia-Lanzo Zone, Western Alps, Italy. Contrib Mineral Petrol 93:322–334
Koons PO, Thompson AB (1985) Non-mafic rocks in the greenschist, blueschist and eclogite facies. Chem Geol 50:3–30
Lardeaux JM, Gosso G, Kienast JR, Lombardo B (1982) Relations entre le métamorphisme et la déformation dans la zone de Sesia-Lanzo (Alpes occidentales) et le problème de l'écologisation de la croûte continentale. Bull Soc Geol France 24:793–800
Miller C (1977) Mineral paragenesis recording the P, T history of Alpine Eclogites in the Tauern Window, Austria. Neues Jahrb Mineral Abh 130:69–77
Ohta Y, Hirijima T, Hiroi Y (1986) Caledonian high-pressure metamorphism in Central Western Spitsbergen. Geol Soc Am Mem 164:205–216
Pognante U, Talarico F, Rastelli N, Ferranti N (1987) High-pressure metamorphism in the nappes of the Valle dell' Orco trraverse (Western Alps collisional belt). J Metamorph Geol 5:397–414
Powell R, Holland TJB (1988) An internally consistent dataset with uncertainties and correlations: 3. applications to geobarometry, worked examples and a computer program. J Metamorph Geol 6:173–204
Powell R, Holland TJB (1990) Calculated mineral equilibria in the pelite system. KFMASH (K2O−FeO−MgO−Al2O3−SiO2 −H2O). Am Mineral (in press)
Schliestedt M (1980) Phasengleichgewichte an Hochdruckgestein von Sifnos, Griechenland. PhD Dissertation, Technische Universität Carolo-Wilhelmina, Braunschweig
Thurston SP (1985) Structure, petrology and metamorphic history of the Nome Group blueschist terrane, Salmon Lake area, Seward Peninsula, Alaska. Geol Soc Am Bull 96:600–617
Triboulet C (1974) Les glaucophanites et roches associées de l'île de Groix (Morbihan, France): étude minéralogique et pétrogénétique. Contrib Mineral Petrol 45:65–90
Yokoyama K, Brothers RN, Black PM (1986) Regional eclogite facies in the high-pressure metamorphic belt of New Caledonia. Geol Soc Am Mem 164:407–423
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Guiraud, M., Holland, T. & Powell, R. Calculated mineral equilibria in the greenschist-blueschist-eclogite facies in Na2O−FeO−MgO−Al2O3−SiO2−H2O. Contr. Mineral. and Petrol. 104, 85–98 (1990). https://doi.org/10.1007/BF00310648
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DOI: https://doi.org/10.1007/BF00310648