The study of mineral chemistry and estimation of metamorphic temperature and pressure of the garnet amphibolites from the Hamedan area

Abstract

Garnet amphibolite is a member of the Hamedan regional metamorphic rocks (the Sanandaj-Sirjan zone). The present study is the first report of mineral compositions and P-T condition of the Hamedan region area garnet amphibolites. The garnet amphibolites can be divided into two varieties based on their mineral assemblages including epidote garnet amphibolite and biotite garnet amphibolite.  Electron microprobe analysis show that they contain magnesio- hornblende, andesine and syderophyllite biotite and their garnets have chemical zoning with almandine and pyrope increasing towards the rims. Thermobarometry studies indicate that these rocks have been metamorphosed to lower to middle-amphibolite facies but the biotite bearing samples endured higher metamorphism degree that is consistent with their mineral assemblages. Although, regarding the relatively small differences between the estimated pressures and temperatures, different chemical composition of their parent rocks should be considered as a factor for determination of their final mineral assemblages. Whole rock analysis together with the mineral assemblages show that the garnet amphibolites are of para-amphibolite type and high K2O contents of the biotite bearing ones is the most important difference between these rocks which can be attributed to high impurities of the parent rocks. Overall, the thermobarometry results are consistent with high T-low P metamorphism (andalusite-sillimanite series) that is characteristic for the Sanandaj-Sirjan zone.

Keywords


[1] Sepahi A. A., Whiteny D. L., Baharifar A. A., “Petrogenesis of andalusite–kyanite–sillimanite veins and host rocks, Sanandaj-Sirjan metamorphic belt, Hamadan, Iran”, Journal of metamorphic geology 22 (2004) 119–134.

]2 [بهاری فر، ع.ا.، “پترولوژی سنگ های دگرگونی منطقه همدان”، پایان نامه دکتری، دانشگاه تربیت معلم، (1383).

[3] Mohajjel M., Baharifar A., Moinevaziri H., Nozaem R., “Deformation history, micro-structure and P-T-t path in ALS-bearing schists, southeast Hamadan, Sanandaj-Sirjan zone, Iran”, Journal of Geological Society of Iran 1 (2006) 11–19.

[4] Mohajjel M., Fergusson C. L., Sahandi M. R., “Cretaceous–Tertiary convergence and continental collision, Sanandaj–Sirjan Zone, western Iran”, Journal of Asian Earth Sciences 21 (2003) 397–412.

[5] Berberian M., Alavitehrani N., “Structural analysis of Hamadan Metamorphic Tectonites”, In: Berberian M., (Ed.), “Contribution to the Seismotectonics of Iran (part 3)”, Geological Survey of Iran, Tehran, (1977) pp. 239–260.

[6] Berberian M., “Three phases of metamorphism in Haji-Abad quadrangle (southern extremity of the Sanandaj-Sirjan structural Zone): a palaeotectonic discussion”, Geological Survey of Iran, Tehran, (1977).

[7] Ghasemi A., Talbot C.J., “A new tectonic scenario for the Sanandaj–Sirjan Zone (Iran)”, Journal of Asian Earth Sciences 26 (2006) 683–693.

]8 [اشراقی ص.ع.، جعفریان م.ب.، اقلیمی ب.، "نقشه زمین‌شناسی 1:100000 سنقر"، سازمان زمین‌شناسی کشور (1375).

[9] Shahbazi H., Siebel W., Pourmoafee M., Ghorbani M., Sepahi A.A., Shang C.K.,Vousoughi Abedini M., “Geochemistry and U–Pb zircon geochronology of the Alvand plutonic complex in Sanandaj–Sirjan Zone (Iran): New evidence for Jurassic magmatism”, Journal of Asian Earth Sciences, 39 (2010) 668-683.

[10] Vernon R.H., “A practical guide to rock microstructure”, Cambridge University Press, New York (2004).

[11] Whitney D. L., Evans B. W., “Abbreviations for names of rock-forming minerals”, American Mineralogist 95 (2010) 185–187.

[12] Leake B. E., Woolley A. R., Arps C. E. S., Birch W. D., Gilbert M. C., Grice J. D., Hawthorne F. C., Kato F. C., Kisch H. J., Krichovichev V. G., Linthout K., Laird J., Mandarino J. A., Maresch W. V., Nickel E. H., Rock N. M. S., Schumacher J. C., Smith D. C., Stephenson N. C. N., Ungaretti L., Whittaker E. J. W., Youzhi G., “Nomenclature of amphiboles: report of the subcommittee on amphiboles of the International Mineralogical Association, Commission on New Minerals and Mineral Names”, American Mineralogist 82 (1997) 1019–1037.

[13] Grew E., Locock A., Mikks S. J., Galuskina I. O., Galuskin E. V., Halenius U., “Nomenclature of the garnet supergroup”, American Mineralogist 98 (2013) 785–811.

[14] Deer W. A., Howie R. A., Zussman J., “Rock forming minerals: Tectosillicates”, John Wiley & Sons, New York (1963).

[15] Deer W. A., Howie R. A., Zussman J., “Rock-forming minerals: Micas”, Longman, London (1982).

[16] Franz G., Liebscher A., “Physical and Chemical Properties of the Epidote Minerals – An Introduction”, Reviews in Mineralogy & Geochemistry 56 (2004) 1-82.

[17] Walker K. R., Joplin G. A., Lovering J. F., Green R., “Meta‌morphic and metasomatic convergence of basic igneous rocks and lime‌ magnesia sediments of the Precambrian of north-western Queensland”, Journal of Geology Society Australia, 6 (1960) 149-178.

[18] Barton M. D., Ilchik R. P., Marikos M. A., “Metasomatism”, In: Kerrick D. M., (Ed) Contact Metamorphism, Reviews in Mineralogy 26 (1991) 321-350.

[19] Winter J. D., “Principles of Igneous and Metamorphic Petrology”, Prentice Hall, (2010).

[20] Grapes R. H., Hoskin P. W. O., “Epidote group minerals in low–medium pressure metamorphic terranes”, Reviews in Mineralogy and Geochemistry 56 (2004) 301-345.

[21] Bucher K., Grapes R., “Petrogenesis of metamorphic rocks”, Springer, Berlin (2011).

[22] Fry N., “The field description of metamorphic rocks”, Geological society of London handbook, London (1984).

[23] Graham C., Powell R., “A garnet-hornblende geothermometer: calibration, testing, and application to the Pelona Schist, Southern California”, Journal of metamorphic geology 2 (1984) 13-31.

[24] Holland T. J. B., Blundy J., “Non-ideal interactions in calcic amphiboles and their bearing on amphibole-plagioclase thermometry”, Contribution to Mineralogy and Petrology 116 (1994) 433–447.

[25] Wu C. M., Pan Y. S., Wang K. Y., Zhang J., “A report on a Biotite − calcic hornblende geothermometer”, Acta Geologica Sinica, 76 (2002) 126 – 131

[26] Kohn M. J., Spear F. S., “Two new geobarometers for garnet amphibolites, with applications to southeastern Vermont”, American Mineralogist 75 (1990) 89-96.

[27] Zenk M., Schulz B., “Zoned Ca-amphiboles and related P-T evolution in metabasites from the classical Barrovian metamorphic zones in Scotland”, Mineralogical Magazine 68 (2004) 769-786.

[28] Gerya T. V., Perchuk L. L., Triboulet C., Audren C., Sez’ko A. I., “Petrology of the Tumanshet Zonal Metamorphic Complex, Eastern Sayan”, Petrology 5 (1997) 503–533.

[29] Miyashiro A., “Metamorphism and metamorphic belts”, Allen & Unwin, London, England, (1973).

[30] Apted M., Liuo J. G., “Phase relations among greenschist, epidote-amphibolite, and amphibolite in a basaltic system”, American Journal of science 283 (1983) 328-354.

[31] Robinson P., Spear F. S., Schumacher J., Laird J., Klein C., Evans B., Doolan B., “Phase relations of metamorphic amphiboles: natural occurrence and theory”, In: Veblen, D.R., Ribbe, P.H. (Eds.), Amphiboles: Petrology and experimental phase relations. Mineralogical Society of America, Washington, D.C., (1982) 1–227.

[32] Schumacher J. C., “Metamorphic amphiboles: composition and coexistence”, Reviews in Mineralogy & Geochemistry 67 (2007) 359–416.

[33] Tracy R., Robinson P., Thompson A. B., “Garnet composition and zoning in the determination of temperature and pressure of metamorphism, central Massachusetts”, American Mineralogist 61 (1976) 762-775.

[34] Monfaredi B., Hauzenberger C., Neubauer F, Shakerardakani F., Halama R., “Quantitative determination of the prograde P-T path by garnet zonation pattern from the Buchan-type pelitic schists of the Hamadan crystalline basement, Sanandaj-Sirjan zone, western Iran”, 17th European Geosciences :union: conference, Vienna, Austria April, 12-17 (2015).