Contributions to Mineralogy and Petrology

, Volume 96, Issue 2, pp 212–224 | Cite as

Phengite geobarometry based on the limiting assemblage with K-feldspar, phlogopite, and quartz

  • Hans -Joachim Massonne
  • Werner Schreyer


Following and extending the early work of Velde (1965) the pressure-temperature dependence of the compositions of potassic white micas coexisting with K-feldspar, quartz, and phlogopite in the model system K2O-MgO-Al2O3-SiO2-H2O was investigated up to fluid pressures of 24 kbar by synthesis experiments. There is a strong, almost linear increase of the Si content per formula unit (p.f.u.) of phengite, ideally KAl2−xMgx[Al1−xSi3+xO10] (OH)2 with pressure, as well as a moderate decrease of Si (or x) with temperature. The most siliceous phengite with Si near 3.8 p.f.u. becomes stable near 20 kbar depending on temperature. However, contrary to Velde's assumption, these phengites coexisting with the limiting assemblage are invariably not of an ideal dioctahedral composition (as given by the above formula) but have total octahedral occupancies as high as about 2.1 p.f.u.

The stability field of the critical assemblage phengite — K-feldspar — phlogopite — quartz ranges, in the presence of excess H2O, from at least 350° C to about 700° C but has an upper pressure limit in the range 16–22 kbar, when K-feldspar and phlogopite react to form phengite and a K, Mg-rich siliceous fluid.

For the purpose of using these phase relationships as a new geobarometer for natural rocks, the influence of other components in the phengite (F, Fe, Na) is evaluated on the basis of literature data. Water activities below unity shift the Si isopleths of phengite towards higher pressures and lower temperatures, but the effects are relatively small. Tests of the new geobarometer with published analytical and PT data on natural phengite-bearing rocks are handicapped by the paucity of reliable values, but also by the obvious lack of equilibration of phengite compositions in many rocks that show zonation of their phengites or even more than one generation of potassic white micas with different compositions. From natural phengites that do not coexist with the limiting assemblage studied here but still with a Mg, Fe-silicate, at least minimum pressures can be derived with the use of the data presented.


Siliceous Fluid Pressure Phase Relationship Stability Field Minimum Pressure 
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  1. Althaus E, Karotke E, Nitsch KH, Winkler HGF (1970) An experimental re-examination of the upper stability limit of muscovite plus quartz. Neues Jahrb Mineral Monatsh 1970:325–336Google Scholar
  2. Beccaluva L, Macciotta GP, Messiga B, Piccardo GB (1979) Petrology of the blue-schists metamorphic ophiolites of the Montenotte Nappe (Western Liguria — Italy). Ofioliti 4:1–36Google Scholar
  3. Berman RG, Brown ThH (1985) Heat capacity of minerals in the system Na2O-K2O-CaO-MgO-FeO-Fe2O3-Al2O3 -SiO2-TiO2-H2O-CO2: representation, estimation, and high temperature extrapolation. Contrib Mineral Petrol 89:168–183Google Scholar
  4. Brown EH (1975) A petrogenetic grid for reactions producing biotite and other Al-Fe-Mg silicates in the greenschist facies. J Petrol 16:258–271Google Scholar
  5. Brown P, Essene EJ, Peacor DR (1978) The mineralogy and petrology of manganese-rich rocks from St. Marcel, Piedmont, Italy. Contrib Mineral Petrol 67:227–232Google Scholar
  6. Chatterjee ND, Johannes W (1974) Thermal stability and standard thermodynamic properties of synthetic 2M1-muscovite, KAl2[AlSi3O10(OH)2]. Contrib Mineral Petrol 48:89–114Google Scholar
  7. Chopin C (1984) Coesite and pure pyrope in high-grade blueschists of the Western Alps: a first record and some consequences. Contrib Mineral Petrol 86:107–118Google Scholar
  8. Chopin C, Maluski H (1980) 40Ar-39Ar dating of high pressure metamorphic micas from the Gran Paradiso Area (Western Alps): Evidence against the blocking temperature concept. Contrib Mineral Petrol 74:109–122Google Scholar
  9. Cimmino F, Messiga B (1979) I calcescisti del Gruppo di Voltri (Liguria Occidentale): Le variazioni compositionali del miche bianche in rapporto alla evoluzione tectonico-metamorfica alpina. Ofioliti 4:269–294Google Scholar
  10. Crowley MS, Roy R (1964) Crystalline solubility in the muscovite and phlogopite groups. Am Mineral 49:348–362Google Scholar
  11. Day HW (1973) The high temperature stability of muscovite plus quartz. Am Mineral 58:255–262Google Scholar
  12. Dietrich H (1983) Zur Petrologie und Metamorphose des Brennermesozoikums (Stubaier Alpen, Tirol). Tschermaks Mineral Petrogr Mitt 31:235–257Google Scholar
  13. Ernst WG (1963) Significance of phengitic micas from low-grade schists. Am Mineral 48:1357–1373Google Scholar
  14. Ernst WG, Dal Piaz GV (1978) Mineral parageneses of eclogitic rocks and related mafic schists of the Piemonte ophiolite nappe, Breuil-St. Jacques area, Italian Western Alps. Am Mineral 63:621–640Google Scholar
  15. Evans BW (1965) Application of a reaction rate method to the breakdown equilibria of muscovite and muscovite plus quartz. Am J Sci 263:647–667Google Scholar
  16. Frey M, Hunziker JC, O'Neil JR, Schwander HW (1976) Equilibrium-disequilibrium relations in the Monte Rosa Granite, Western Alps: Petrological, Rb-Sr and stable isotope data. Contrib Mineral Petrol 55:147–179Google Scholar
  17. Guidotti CV, Sassi FP (1976) Muscovite as a petrogenetic indicator mineral in pelitic schists. Neues Jahrb Mineral Abh 127:97–142Google Scholar
  18. Guidotti CV, Sassi FP (1986) Classification and correlation of metamorphic facies series by means of muscovite b 0 data from low-grade metapelites. Neues Jahrb Mineral Abh 153:363–380Google Scholar
  19. Halbach H, Chatterjee ND (1982) An empirical Redlich-Kwongtype equation of state for water to 1,000° C and 200 kbar. Contrib Mineral Petrol 79:337–345Google Scholar
  20. Harley SL, Green DH (1981) Petrogenesis of eclogite inclusions in the Moses Rock Dyke, Utah, USA. Tschermaks Mineral Petrogr Mitt 28:131–155Google Scholar
  21. Heinrich CA (1982) Kyanite-eclogite to amphibolite facies evolution of hydrous mafic and pelitic rocks, Adula Nappe, Central Alps. Contrib Mineral Petrol 81:30–38Google Scholar
  22. Hoschek G (1980) The effect of Fe-Mg substitution on phase relations in marly rocks of the Western Hohe Tauern (Austria). Contrib Mineral Petrol 75:123–128Google Scholar
  23. Huang WL, Wyllie PJ (1974) Melting relations of muscovite with quartz and sanidine in the K2O-Al2O3-SiO2-H2O system to 30 kilobars and an outline of paragonite melting relations. Am J Sci 274:378–395Google Scholar
  24. Katagas C, Baltatzis E (1980) Coexisting celadonitic muscovite and paragonite in chlorite zone metapelites. Neues Jahrb Mineral Monatsh 1980:206–214Google Scholar
  25. Lardeaux J-M, Gosso G, Kienast J-R, Lombardo B (1983) Chemical variations in phengitic mica of successive foliations within the eclogitic micaschists complex, Sesia-Lanzo Zone (Italy, Western Alps) Bull Mineral 106:673–689Google Scholar
  26. Lattard D (1974) Les roches du faciès vert dans la zone de Sesia-Lanzo, Alpes Italiennes. Thèse 3ème cycle, Laboratoire de Petrologie Université Paris VIGoogle Scholar
  27. Massonne H-J (1986) Breakdown of K-feldspar+phlogopite to phengite+K, Mg-rich silicate melt under the metamorphic conditions of a subduction zone. Int Symp Exp Mineral Geochem, Nancy 1986, pp 97–98Google Scholar
  28. Massonne H-J, Schreyer W (1980) Erhöhung der Muscovitstabilität durch MgSi-Einbau im Bereich von 3 bis 35 kb 223-01. Fortschr Mineral 58 Beih 1:88–90Google Scholar
  29. Massonne H-J, Schreyer W (1985) Phengite barometry in assemblages with kyanite, Mg-rich silicates, and a SiO2 phase. Terra Cognita 5:432Google Scholar
  30. Massonne H-J, Schreyer W (1986) High-pressure syntheses and X-ray properties of white micas in the system K2O-MgO-Al2O3-SiO2-H2O. Neues Jahrb Mineral Abh 153:177–215Google Scholar
  31. Mather JD (1970) The biotite isograd and the lower greenschist facies in the Dalradian rocks of Scotland. J Petrol 11:253–275Google Scholar
  32. McDowell SD, Elders WA (1980) Authigenic layer silicate minerals in borehole Elmore 1, Salton Sea geothermal field, California, USA. Contrib Mineral Petrol 74:293–310Google Scholar
  33. Miller Chr (1977a) Chemismus und phasenpetrologische Untersuchungen der Gesteine aus der Eklogitzone des Tauernfensters, Österreich. Tschermaks Mineral Petrogr Mitt 24:221–277Google Scholar
  34. Miller Chr (1977b) Mineral parageneses recording the p, T history of Alpine eclogites in the Tauern Window, Austria. Neues Jahrb Mineral Abh 130:69–77Google Scholar
  35. Moore DE, Liou JG (1979) Mineral chemistry of some Franciscan blueschist facies metasedimentary rocks from the Diablo Range, California. Geol Soc Am Bull II, 90:1737–1781Google Scholar
  36. Němec D (1980) Fluorine phengites from tin-bearing orthogneisses of the Bohemian-Moravian Heights, Czechoslovakia. Neues Jahrb Mineral Abh 139:155–169 (1980)Google Scholar
  37. Powell R, Evans JA (1983) A new geobarometer for the assemblag ebiotite-muscovite-chlorite-quartz. J Metam Geol 1:331–336Google Scholar
  38. Råheim A (1975) Mineral zoning as a record of P,T history of Precambrian eclogites and schists in western Tasmania. Lithos 8:221–236Google Scholar
  39. Råheim A (1976) Petrology of eclogites and surrounding schists from the Lyell Highway — Collingwood River Area. J Geol Soc Aust 23:313–327Google Scholar
  40. Robert J-L (1976) Phlogopite solid solutions in the system K2O -MgO-Al2O3-SiO2-H2O. Chem Geol 17:195–212Google Scholar
  41. Robie RA, Bethke PM, Beardsley KM (1967) Selected X-ray crystallographic data molar volumes, and densities of minerals and related substances. Geol Surv Bull 1248Google Scholar
  42. Robie RA, Hemingway BS, Fisher JR (1979) Thermodynamic properties of minerals and related substances at 298.15 K and 1 bar (105 Pascals) pressure and at higher temperatures. Geol Surv Bull 1452Google Scholar
  43. Saliot P, Velde B (1982) Phengite compositions and post-nappe high-pressure metamorphism in the Pennine zone of the French Alps. Earth Planet Sci Lett 57:133–138Google Scholar
  44. Schreyer W, Massonne H-J, Chopin C (1987) Continental crust subducted to depths near 100 km: Implications for magma and fluid genesis in collision zones. In: Mysen BO (ed) Magmatic processes: Physicochemical principles. Geochem Soc Spec Publ 1 (in press)Google Scholar
  45. Seifert F (1970) Low-temperature compatibility relations of cordierite in haplopelites of the system K2O-MgO-Al2O3-SiO2 -H2O. J Petrol 11:73–99Google Scholar
  46. Smith D, Zientek M (1979) Mineral chemistry and zoning in eclogite inclusions from Colorado Plateau diatremes. Contrib Mineral Petrol 69:119–131Google Scholar
  47. Sorensen SS (1986) Petrologic and geochemical comparison of the blueschist and greenschist units of the Catalina Schist terrane, Southern California. In: Evans BW, Brown EH (eds) Blueschists and eclogites. Geol Soc Am Mem 164:59–75Google Scholar
  48. Spear FS, Selverstone J, Hickmott D, Crowley P, Hodges KV (1984) P-T paths from garnet zoning: A new technique for deciphering tectonic processes in crystalline terranes. Geology 12:87–90Google Scholar
  49. Stöckhert B (1985) Compositional control on the polymorphism (2M 1 -3 T) of phengitic white mica from high pressure parageneses of the Sesia Zone (lower Aosta valley, Western Alps, Italy). Contrib Mineral Petrol 89:52–58Google Scholar
  50. Storre B, Karotke E (1972) Experimental data on melting reactions of muscovite+quartz in the system K2O-Al2O3-SiO2-H2O to 20 kb water pressure. Contrib Mineral Petrol 36:343–345Google Scholar
  51. Velde B (1965) Phengite micas: Synthesis, stability, and natural occurrence. Am J Sci 263:886–913Google Scholar
  52. Velde B (1966) Upper stability of muscovite. Am Mineral 51:924–929Google Scholar
  53. Velde B (1967) Si+4 content of natural phengites. Contrib Mineral Petrol 14:250–258Google Scholar
  54. Wang Y, Fuh TM (1966) A re-examination of the hydrothermal breakdown of muscovite. Proc Geol Soc China 9:31–45Google Scholar
  55. Wones DR (1967) A low pressure investigation of the stability of phlogopite. Geochim Cosmochim Acta 31:2248–2253Google Scholar
  56. Yoder HS Jr, Eugster HP (1955) Synthetic and natural muscovites. Geochim Cosmochim Acta 8:225–280Google Scholar

Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • Hans -Joachim Massonne
    • 1
  • Werner Schreyer
    • 1
  1. 1.Institut für MineralogieRuhr-UniversitätBochum 1Federal Republic of Germany

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