Abstract
An absarokite (SiO2 47.72 wt %, K2O 3.41 wt %) occurs in the Katamata volcano, SW Japan. The rock carries phenocrysts of olivine, phlogopite, clinopyroxene, and hornblende. Chemical compositions of bulk rock (FeO*/ MgO 0.73) and minerals (Mg-rich olivine and phlogopite, Cr-rich chromite) suggest that the absarokite is not differentiated. Melting experiments at high pressures on the Katamata absarokite have been conducted. The completely anhydrous absarokite melt coexists with olivine, orthopyroxene, and clinopyroxene at 1310° C and 1.0 GPa. The melt with 3.29 wt % of H2O also coexists with the above three phases at 1230° C and 1.4 GPa; phlogopite appears at temperatures more than 80° C below the liquidus. On the other hand, the melt is not saturated with lherzolite minerals in the presence of 5.13 wt % of H2O and crystallizes olivine and phlogopite as liquidus phases; the stability limit of phlogopite is little affected at least by the present variation of H2O content in the absarokite melt. It is suggested that the absarokite magma was segregated from the upper mantle at 1170° C and 1.7 GPa leaving a phlogopite lherzolite as a residual material on the basis of the above experimental results and the petrographical observation that olivine and phlogopite crystallize at an earlier stage of crystallization sequence than clinopyroxene. The contribution of phlogopite at the stage of melting processes is also suggested by the geochemical characteristics that the absarokite is more enriched in Rb, K, and Ba and depleted in Ca and Na than a typical alkali olivine basalt from the same volcanic field.
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References
Bates RL, Jackson JA (1980) Glossary of geology. American Geological Institute, Falls Church
Bence AE, Albee AL (1968) Empirical correction factors for the electron microanalysis of silicates and oxides. J Geol 76:382–403
Boyd FR, England JL (1960) Apparatus for phase-equilibrium measurements at pressures up to 50 kilobars and temperatures up to 1750° C. J Geophys Res 65:741–748
Hamilton DL, Burnham CW, Osborn EF (1964) The solubility of water and effect of oxygen fugacity and water content on crystallization in mafic magmas. J Petrol 5:21–39
Iddings JP (1895) Absarokite-shoshonite-banakite series. J Geol 3:935–959
Kobayashi K, Nakada M (1978) Magnetic anomalies and tectonic evolution of the Shikoku Inter-Arc Basin. J Phys Earth 26:391–402
Koyaguchi T (1986) Textural and compositional evidence for magma mixing and its mechanism, Abu volcano group, Southwest Japan. Contrib Mineral Petrol 93:33–45
Kushiro I (1968) Compositions of magmas formed by partial zone melting of the Earth's upper mantle. J Geophys Res 73:619–634
Lloyd FE, Bailey DK (1975) Light element metasomatism of the continental mantle: the evidence and the consequence. Phys Chem Earth 9:389–416
Matsumoto R, Urabe T (1980) An automatic analysis of major elements in silicate rocks with X-ray fluorescence spectrometer using fused disc samples. J Japan Assoc Mineral Petrol Econ Geol 75:272–278 (in Japanese)
Meen JK (1987) Formation of shoshonites from calcalkaline basalt magmas: geochemical and experimental constraints from the type locality. Contrib Mineral Petrol 97:331–351
Morrison GW (1980) Characteristics and tectonic setting of the shoshonite rock association. Lithos 13:97–108
Mysen BO, Kushiro I (1977) Compositional variations of coexisting phases with degree of melting of peridotite in the upper mantle. Am Mineral 62:845–865
Nakanishi I (1980) Precursor to ScS phases and dipping interface in the upper mantle beneath southwestern Japan. Tectonophysies 69:1–35
O'Hara MJ, Yoder HS Jr (1967) Formation and fractionation of basaltic magmas at high pressures. Scot J Geol 3:67–117
Peccerillo A, Taylor SR (1976) Geochemistry of Ecocene calc-alkaline volcanic rocks from the Kastamonu area, Northern Turkey. Contrib Mineral Petrol 58:63–81
Roeder PL, Emslie RF (1970) Olivine-liquid equilibrium. Contrib Mineral Petrol 29:275–289
Shaw DM (1970) Trace element fractionation during anatexis. Geochim Cosmochim Acta 34:237–243
Takahashi E (1981) Melting relations of an alkali-olivine basalt to 30 kbars, and their bearing on the origin of alkali basalt magmas. Carnegie Inst Washington Yearb 79:271–276
Tatsumi Y, Sakuyama M, Fukuyama H, Kushiro I (1983) Generation of arc basalt magmas and thermal structure of the mantle wedge in subduction zones. J Geophys Res 88:5815–5825
Turi B, Taylor HP Jr (1976) Oxygen isotope study of potassic volcanic rocks of the Roman Province, central Italy. Contrib Mineral Petrol 55:1–31
Wendlandt RF, Eggler DH (1980) The origins of potassic magmas: 1. melting relations in the systems KAlSiO4-Mg2SiO4-SiO2 and KAlSiO4-MgO-SiO2-CO2 to 30 kilobars. Am J Sci 280:385–420
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Tatsumi, Y., Koyaguchi, T. An absarokite from a phlogopite lherzolite source. Contr. Mineral. and Petrol. 102, 34–40 (1989). https://doi.org/10.1007/BF01160189
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DOI: https://doi.org/10.1007/BF01160189