Abstract
The textures and kinetics of reaction between plagioclase and melts have been investigated experimentally, and origin of dusty plagioclase in andesites has been discussed. In the experiments plagioclase of different compositions (An96, An61, An54, An23, and An22) surrounded by glasses of six different compositions in the system diopside-albite-anorthite was heated at temperatures ranging from 1,200 to 1,410° C for 30 min to 88 h. Textures were closely related to temperature and chemical compositions. A crystal became smaller and rounded above the plagioclase liquidus temperature of the starting melt (glass) and remained its original euhedral shape below the liquidus. Whatever the temperature, the crystal-melt interface became rough and often more complicated (sieve-like texture composed of plagioclase-melt mixture in the scale of a few μm was developed from the surface of the crystal inward; formation of mantled plagioclase) if the crystal is less calcic than the plagioclase in equilibrium with the surrounding melt, and the interface remained smooth if the crystal is more calcic than the equilibrium plagioclase. From these results the following two types of dissolution have been recognized; (1) a crystal simply dissolves in the melt which is undersaturated with respect to the phase (simple dissolution), and a crystal is partially dissolved to form mantled plagioclase by reaction between sodic plagioclase and calcic melt (partial dissolution). The amount of a crystal dissolved and reacted increased proportional to the square root of time. This suggests that these processes are controlled by diffusion, probably in the crystal.
Mantled plagioclase produced in the experiments were very similar both texturally and chemically to some of the so-called resorbed plagioclase in igneous rocks. Chemical compositions and textures of plagioclase phenocrysts in island-arc andesites of magma mixing origin have been examined. Cores of clear and dusty plagioclase were clacic (about An90) and sodic (about An50), respectively. This result indicates that dusty plagioclases were formed by the partial melting due to reaction between sodic plagioclase already precipitated in a dacitic magma and a melt of intermediate composition in a mixed magma during the magma mixing.
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References
Bence AE, Albee AL (1968) Empirical correction for the electron microanalysis of silicates and oxides. J Geol 76:382–403
Bowen NL (1928) The evolution of the igneous rocks. Princeton University Press, NJ, pp 332
Dungan MA, Rhodes JM (1978) Residual glasses and melt inclusions in basalts from DSDP Legs 45 and 46: evidence of magma mixing. Contrib Mineral Petrol 67:417–431
Eichelberger JC (1978) Andesites in island arcs and continental margins: relationship to crustal evolution. Bull Volcanol 41:480–500
Hibbard MJ (1981) The magma mixing origin of mantled feldspars. Contrib Mineral Petrol 76:158–170
Kuno H (1950) Petrology of Hakone volcano and the adjacent areas, Japan. Geol Soc Am Bull 61:957–1020
Kuo LC, Kirkpatrick RJ (1982) Pre-eruption history of phyric basalts from DSDP Legs 45 and 46: evidence from morphology and zoning patterns in plagioclase. Contrib Mineral Petrol 79:13–27
Kuo LC, Kirkpatrick RJ (1984) Kinetics of crystal dissolution in the system diopside-forsterite-silica. Am Jour Sci (in press)
Gerlach DC, Grove TL (1982) Petrology of Medicine Lake Highland volcanics: characterization of endmembers of magma mixing. Contrib Mineral Petrol 80:147–159
Harris C, Bell JD (1982) Natural partial melting of syenite blocks from Ascension Island. Contrib Mineral Petrol 79:107–113
Lofgren GE, Norris PN (1981) Experimental duplication of plagioclase sieve and overgrowth textures. Geol Soc Am Abstr Progr
McBirney AR (1979) Effects of assimilation. In: Yoder HS Jr (ed) The evolution of igneous rocks: fiftieth anniversary perspectives, Princeton University Press, Princeton NJ
MacDonald GA, Katsura T (1965) Eruption of Lassen Peak, Cascade Range, California, in 1915: example of mixed magmas. Geol Soc Am Bull 76:475–482
Rhodes JM, Dungan MA, Blanchard DP, Long PE (1979) Magma mixing at mid-ocean ridges: evidence from basalts chilled near 22° N on the Mid-Atlantic Ridge. Techtonophysics 55:35–61
Sakuyama M (1978) Petrographic evidence of magma mixing in Shirouma-Oike volcano, Japan. Bull Volcanol 41:501–512
Sakuyama (1981) Petrogical study of the Myoko and Kurohime volcanos, Japan: crystallization sequence and evidence for magma mixing. J Petrol 22:553–583
Scherer G, Vergano PJ, Uhlmann DR (1970) A study of quartz melting. Phys Chem Glass 11:53–58
Tsuchiyama A, Takahashi E (1983) Melting kinetics of a plagioclase feldspar. Contrib Mineral Petrol 84:345–354
Vance JA (1965) Zoning in igneous plagioclase: patchy zoning. J Geol 73:636–651
Wagstaff FE (1969) Crystallization and melting kinetics of cristobalite. J Am Ceram Soc 52:650–654
Watson B (1982) Basalt contamination by continental crust: some experiments and models. Contrib Mineral Petrol 80:73–87
Weill DF, Hon R, Navrotsky A (1979) The igneous system CaMg-Si2O6-CaAl2Si2O8-NaAlSi3O8: variation of a classic theme by Bowen. In: Hargraves RB (ed) Physics of magmatic processes, Princeton University Press, Princeton, NJ
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Tsuchiyama, A. Dissolution kinetics of plagioclase in the melt of the system diopside-albite-anorthite, and origin of dusty plagioclase in andesites. Contr. Mineral. and Petrol. 89, 1–16 (1985). https://doi.org/10.1007/BF01177585
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DOI: https://doi.org/10.1007/BF01177585