Hostname: page-component-84b7d79bbc-g5fl4 Total loading time: 0 Render date: 2024-07-27T18:49:41.270Z Has data issue: false hasContentIssue false
  • English
  • Français

Omphacite-diopside vein in an omphacitite block from the Osayama serpentinite melange, Sangun-Renge metamorphic belt, southwestern Japan

Published online by Cambridge University Press:  05 July 2018

Tatsuki Tsujimori
Tatsuki Tsujimori*
Affiliation:
Department of Earth Sciences, Faculty of Science, Kanazawa University, Kanazawa 920-11, Japan
Get access Rights & Permissions [Opens in a new window]

Abstract

Omphacite (Jd46.1–52.0Ae0–8.4Aug48.0–51.2) and diopside (Jd4.3–6.3Ae0–0.4Aug93.6–95.6) coexist in a vein cutting an omphacitite block in a serpentinite melange of the Oeyama ophiolite, central Chugoku Mountains. The compositional gap between omphacite and diopside is significantly wider than for other omphacitediopside pairs reported in the literature. The intergrowth texture of the omphacite-diopside vein suggests that the clinopyroxene pair was contemporaneously crystallized in the fracture from a Ca-bearing, alkali-rich fluid in a sub-solvus condition. Such a fluid may have been introduced from the surrounding serpentinized clinopyroxene-bearing harzburgite. The stability of omphacite and Al-rich pumpellyite in the matrix and the omphacite-diopside vein indicate that the earlier matrix recrystallization and later fracture filling may have both taken place under high-P-T condition during the melange-forming stage.

Keywords

omphacitediopsideimmiscibilityserpentinite melangeOeyama ophioliteSangun-Renge metamorphic belt
Type
Mineralogy
Information
Mineralogical Magazine , Volume 61 , Issue 409 , December 1997 , pp. 845 - 852
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1997

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bence, A.E. and Albee, A.L. (1968) Empirical correction factors of the electron microanalysis of silicates and oxides. .I. Geol., 76, 382–403.Google Scholar
Banno, S. (1958) Glaucophane schists and associated rocks in the Omi district, Japan. J. Geol. Geogr. Japan, 29, 29-44.Google Scholar
Brown, P., Essene, E.J. and Peacor, D.R. (1978) The mineralogy and petrology of manganese-rich rocks from St. Marcel, Piedmont, Italy. Contrib. Mineral. Petrol., 67, 227-32.CrossRefGoogle Scholar
Carpenter, M.A. (1979) Omphacite from Greece, Turkey, and Guatemala: composition limits of cation ordering. Amer. Mineral., 65, 313—20.Google Scholar
Carpenter, M.A. (1980a) Composition and cation order variations in a sector-zoned blueschist pyroxene. Amer. Mineral., 65, 313-20.Google Scholar
Carpenter, M.A. (1980b) Mechanisms of exsolution in sodic pyroxenes. Contrib. Mineral. Petrol., 71, 289–300.CrossRefGoogle Scholar
Carpenter, M.A., Domeneghetti, M.-C. and Tazzoli, V. (1990) Application of Landau theory to cation ordering in omphaeite I: Equilibrium behavior. Eur. J. Mineral., 2, 7–18.CrossRefGoogle Scholar
Coleman, R.G. (1961) Jadeite deposits of the Clear Creek area, New Idria district, San Benito County, California. J. Petrol., 2, 209-47.CrossRefGoogle Scholar
Enami, M. and Tokonami, M. (1984) Coexisting sodie diopside and omphacite in a Sanbagawa meta-morphic rocks, Japan. Contrib. Mineral. Petrol., 86, 241-7.CrossRefGoogle Scholar
Essene, E.J. and Fyfe, S. (1967) Omphacite in Califomian metamorphic rocks. Contrib. Mineral. Petrol., 15, 1–23.CrossRefGoogle Scholar
Ishiwatari, A. (1991) Time-space distribution and petrologic diversity of Japanese ophiolites. In: Ophiolite Genesis and Evolution of the Oceanic Lithosphere (Peters, Tj. et al., eds.) Kluwer Academic Publishing, Amsterdam, 723-43.CrossRefGoogle Scholar
Matsumoto, T., Tokonami, M. and Morimoto, N. (1975) The crystal structure of omphacite. Amer. Mineral., 60, 634-41.Google Scholar
Morimoto, N., Fabries, J., Ferguson, A.K., Ginzburg, I.V., Ross, M., Seifert, F.A., Zussman, J., Aoki, K. and Gottardi, G. (1988) Nomencla∼tre of pyroxenes. Amer. Mineral., 73, 1123-33.Google Scholar
Nozaka, T. and Shibata, T. (1994) Petrography of primary peridotites from the Ohsa-yama area, Okayama Prefecture. Okayama Univ. Earth Sci. Report, 1, 1-8.Google Scholar
Nozaka, T. and Shibata, T. (1995) Mineral paragenesis in thermally metamorphosed serpentinites, Ohsa-yama, Okayama Prefecture. Okayama Univ. Earth Sci. Report, 2, 1-12.Google Scholar
Philippot, P. and Kienast, J. R. (1989) Chemical-microstructural changes in eclogites in eclogite-facies shear zones (Monviso, Western Alps, north Italy) as indicators of strain history and the mechanism and scale of mass transfer. Lithos, 23, 179-200.CrossRefGoogle Scholar
Tsujimori, T. (1995a) Finding of eclogite from the Sangun-Renge metamorphic belt of the Chugoku district, the Inner Zone of southwestern Japan. Abstracts of 1994 Annual Meeting of the Japanese Association of Mineral., Petrol. Econ. Geol. p. 50. (Japanese with English abstract).Google Scholar
Tsujimori, T. (1995b) Chromian omphacite and ehromian diopside in the tremolite schist blocks from the Osayama serpentinite melange, Sangun-Renge metamorphic belt, southwestern Japan. Abstracts of 1995 Joint Annual Meeting of Janan. Assoc. Min. Pert. Econ. Geol., Min. Soc. Japan and Soc. Resource Geol. p. 33. (in Japanese).Google Scholar
Tsujimori, T. (in press) Geology of the Osayama serpentinite melange in the central Chugoku Mountains, southwestern Japan: 320 Ma blueschist-bearing serpentinite melange beneath a peridotite body of the Oeyama ophiolite. J. Geol. Soc. Japan. (Japanese with English abstract).Google Scholar
Tsujimori, T. and Itaya, T. (submitted) Blueschist-facies metamorphism during Carboniferous orogeny in southwestern Japan: phengite K-Ar ages of blueschist-facies tectonic blocks in a serpentinite melange beneath Early Paleozoic Oeyama ophiolite. Tectonophys. Google Scholar