The system KAlSiO4-Mg2SiO4-SiO2-H2O includes model representatives of (1) hydrous siliceous magma from subducted oceanic crust — the eutectic liquid in KAlSi3O8-SiO2-H2O, and (2) the overlying mantle peridotite — the assemblage forsterite+enstatite (Fo+En). In a series of partly schematic isobaric isothermal sections, the products of hybridization between the model materials at pressures between 20 and 30 kbar have been determined. The liquid dissolves peridotite components with little change in composition. Hybridization is not a simple mixing process, because of the incongruent melting of peridotitic assemblages with phlogopite (Ph). Hybridization causes solidification of the liquid, with products a sequence of three mineral assemblages: Ph, Ph+quartz (Qz), and Ph+En. The products represent an absolute geochemical separation and local concentration of all potassium from the liquid. Hybridization is accompanied by H2O-saturation of melts, and evolution of aqueous fluid. Although there are significant differences between the melt composition and that of the magma rising from subducted oceanic slab, and between Fo+En and the mantle rock, extrapolation of the results suggests that the conclusions can probably be extended to mantle conditions with sodium in the melt, and jadeitic clinopyroxene included in the hybrid products.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Eggler DH (1973) Role of CO2 in melting processes in the mantle. Carnegie Inst Washington Yearb 72:457–467
Holloway JR, Eggler DH (1976) Fluid-absent melting of peridotite containing phlogopite and dolomite. Carnegie Inst Washington Yearb 75:636–639
Huang W-L, Wyllie PJ (1975) Melting reactions in the system NaAlSi3O8-KAlSi3O8-SiO2 to 35 kilobars, dry and with excess water. J Geol 83:737–748
Kennedy GC, Wasserburg GJ, Heard HC, Newton RC (1962) The upper three-phase region in the system SiO2-H2O. Am J Sci 260:501–521
Kushiro I (1969) The system forsterite-diopside-silica with and without water at high pressures. Am J Sci 267-A:269–294
Kushiro I, Yoder HS Jr, Nishikawa M (1968) Effect of water on the melting of enstatite. Geol Soc Am Bull 79:1685–1692
Luth WC (1967) Studies in the system KAlSiO4-Mg2SiO4-SiO2-H2O: I, inferred phase relations and petrologic applications. J Petrol 8:372–416
Modreski PJ, Boettcher AL (1972) The stability of phlogopite and enstatite at high pressures: a model for micas in the interior of the earth. Am J Sci 272:852–869
Modreski PJ, Boettcher AL (1973) Phase relationships of phlogopite in the system K2O-MgO-CaO-Al2O3-SiO2-H2O to 35 kilobars: a better model for micas in the interior of the earth. Am J Sci 273:385–414
Nakamura Y, Kushiro I (1974) Composition of the gas phase in Mg2SiO4-SiO2-H2O at 15 kbar. Carnegie Inst Washington Yearb 73:255–258
Nicholls IA, Ringwood AE (1973) Effect of water on olivine stability in tholeiites and production of silica-saturated magmas in the island arc environment. J Geol 81:285–300
Ringwood AE (1975) Composition and petrology of the earth, 618 p, McGraw-Hill, New York
Sekine T, Wyllie PJ, Baker DR (1981) Phase relationships at 30 kbar for quartz eclogite composition in CaO-MgO-Al2O3-SiO2-H2O with implications for subduction zone magmas. Am Mineral 66:935–950
Stern CR, Wyllie PJ (1978) Phase compositions through crystallization intervals in basalt-andesite-H2O at 30 kbar with implications for subduction zone magmas. Am Mineral 63:641–663
Wendlandt RF, Eggler DH (1980) The origins of potassic magmas: 2. stability of phlogopite in natural spinel lherzolite and in the system KAlSiO4-MgO-SiO2-H2O-CO2 at high pressures and high temperatures. Am J Sci 280:421–458
Yoder HS Jr (1976) Generation of basaltic magma, 265 p. Natl Acad Sci Washington DC
Yoder HS Jr, Kushiro I (1969) Melting of a hydrous phase: phlogopite. Am J Sci 267-A:558–582
About this article
Cite this article
Sekine, T., Wyllie, P.J. Phase relationships in the system KAlSiO4-Mg2SiO4-SiO2-H2O as a model for hybridization between hydrous siliceous melts and peridotite. Contr. Mineral. and Petrol. 79, 368–374 (1982). https://doi.org/10.1007/BF01132066
- Oceanic Crust
- Mineral Assemblage
- Isothermal Section