Kharazmi Journal of Earth Sciences

Kharazmi Journal of Earth Sciences

Petrography, geothermobarometry and tectonomagmatic setting of intrusive rocks in Khuni (Northeast of Anarak, Central Iran)

Authors
University of Isfahan
Abstract
In the southwest of Khuni mountain and the north of Kal-e-Kafi intrusion (northeast of Anarak), the igneous rocks of Khuni are cropped out. They dominantly show porphyritic texture and are similar to monzodiorite in composition. The phenocrysts mainly are clinopyroxene (diopside), amphibole (magnesiohastingsite to magnesian hastingsite), and feldspar (orthoclase in the rim and andesine in the core). Accessory minerals include primary biotite, apatite, sphene, and magnetite. The secondary minerals are biotite, calcite, epidote, tremolite- actinolite, and chlorite. Anti-rapakivi texture in feldspar is petrographic evidence of magma contamination. Application of various geothermobarometric methods for clinopyroxene and amphibole crystals in Khuni rocks yielded a crystallization temperature of ~1150°C for clinopyroxene and pressure range of 7-8 kb and temperatures of ~900-950°C for the amphibole phenocryst. Thermobarometry and chemistry of clinopyroxene and amphibole phenocrysts indicate that the rock-forming melt was formed by melting the continental crust in the Anarak area, as a result of the subduction-related magmatism of Eocene during the Neo-Tethys subduction beneath Central Iran.




Keywords
Subjects

[7] Ahmadian, J., Sarjoughian, F., Lentz, D., Esna-Ashari, A., Murata, M., Ozawa, H. “Eocene K-rich adakitic rocks in the Central Iran: Implications for evaluating its Cu–Au–Mo metallogenic potential”, Ore Geology Reviews, 72)2016) 323-342.
[10] Ranjbar, S., Tabatabaei Manesh, S.M., Mackizadeh, M.A., Tabatabaei, S.H., Parfenova, O.V. “Geochemistry of major and rare earth elements in garnet of the Kal-e Kafi skarn, Anarak Area, Central Iran: Constraints on processes in a hydrothermal system”, Geochemistry International, 54 (2016) 423–438.
[11] Le Garzic, E., Vergés, J., Sapin, F., Saura, E., Meresse, F., Ringenbach, J.C. “Evolution of the NW Zagros Fold-and-Thrust Belt in Kurdistan Region of Iraq from balanced and restored crustal-scale sections and forward modeling”. Journal of Structural Geology 124 (2019) 51–69.
[12] Technoexport, Geological map of Kabudan: Geological survey of Iran, 1:100000 series, sheet 68. 1:250000‚ No. H7. )1984.(
[13] Droop, G. T. R. A “general equation for estimating Fe3+ concentrations in ferromagnesian silicates and oxides from microprobe analyses, using stoichiometric criteria”, Mineralogical Magazine 51(1987) 431-435.
[14] Whitney, D.L. and Evans, B.W. “Abbreviations for names of rock-forming minerals”. American Mineralogist 95 (2010) 185-187.
[15] Deer, W.A., Howie, R.A., Zussman, J., “An introduction to the rock-forming minerals”, Vol. 696. Longman, London (1992).
[16] Hawthorne, F.C., “Amphibole spectroscopy”, Reviews in Mineralogy and Geochemistry, 9(1) (1981)103-139.
[17] Hawthorne, F.C., Oberti, R., “Classification of the amphiboles”, Reviews in Mineralogy and Geochemistry, 67(1) (2007) 55-88.
[18] Chambefort, I., Dilles, J.H., Longo, A., “Amphibole geochemistry of Theyanacocha volcanics, Peru: evidence for diverse sources of magmatic volatiles related to gold ores”, Journal of Petrology, (2013) 1-30.
[19] Strübel, G.and Zimmer, S. H. “Lexikon der Mineralogie”, 2. Auflage, Ferdinand Enke Verlag, Stuttgart (1992).
[20] Morimoto, N., Fabrise, J., Ferguson, A., Ginzburg, I.V., Ross, M., Seifert, F.A., Zussman, J., Aoki, K., and Gottardi, G., “Nomenclature of pyroxene”, Mineralogical Magazin, 52 (1988) 535–555.
[21] Berger, J., Femenias, O., Mercier, J., Demaiffe, D., “Ocean‐floor hydrothermal metamorphism in the Limousin ophiolites (western French Massif Central): evidence of a rare preserved Variscan oceanic marker”, Journal of metamorphic geology, 23(9)(2005(795-812.
[22] Otten, M.T., “The origin of brown hornblende in the Artfjället gabbro and dolerites”, Contributions to Mineralogy and Petrology, 86(2) (1984) 189-199.
[23] Anderson, J.L., Smith, D.R., “The effect of temperature and fO2 on the Al-in-hornblende barometer”, American Mineralogist, 80) 1995(549-559.
[24] Hollister, L.S., Grissom, G.C., Peters, E.K., Stowell, H.H., Sisson, V.B., “Confirmation of the empirical correlation of Al in hornblende with pressure of solidification of calc-alkaline plutons”, American Mineralogist, 72 (1987) 231-239.
[25] Anderson, J.L., “Status of thermobarometry in granitic batholiths”, Transactions of the Royal Society of Edinburgh Earth Sciences, 87) 1996(125-138.
[27] Blundy, J.D., Holland, T.J.B., “Calcic amphibole equilibria and a new amphibole-plagioclase geothermometer”, Contributions to Mineralogy and Petrology, 104 (1990) 208-224.
[28] Ernst, W.G., Liu, J., “Experimental phase-equilibrium study of Al- and Ti-contents of calcic amphibole in MORB- A semiquantitative thermobarometer”, American Mineralogist, 83 (1998) 952- 969.
[29] Holland, T., Blundy, J., “Non-ideal interaction in calcic amphibole and their bearing on amphibole-plagioclase thermometry”, Contribution to Mineralogy and Petrology, 116 (1994) 433-447.
[30] Raase, P., “Al and Ti contents of hornblende, indicators of pressure and temperature of regional metamorphism”, Contributions to Mineralogy and Petrology, 45 (1974) 231 - 236.
[31] Hammarstrom, J.M., Zen, E. “Aluminum in hornblende: An empirical igneous geobarometer”, American Mineralogist, 71 (1986) 1297-1313.
[32] Johnson, M.C., Rutherford, M.J., “Experimental calibration of the aluminum-in-hornblende geobarometer with application to Long Valley caldera (California) volcanic rocks”, Geology, 17(9) (1989) 837-841.
[33] Schmidt, M.W., “Amphibole composition in tonalite as a function of pressure: an experimental calibration of the Al-in-hornblende barometer”, Contributions to Mineralogy and Petrology, 110(2) (1992) 304-310.
[34] Stein, E., Dietl, C., “Hornblende thermobarometry of granitoids from the Central Odenwald (Germany) and their implications for the geotectonic development of the Odenwald”, Mineralogy and Petrology, 72(1) (2001) 185-207.
[35] Helz, R.T., “Phase relations of basalts in their melting range at PH2O=5 kb as a function of oxygen fugacity, Part I: mafic phases”, Journal of Petrology, 14(2) (1973) 249-302.
[36] Soesoo, A., “A multivariate statistical analysis of clinopyroxene composition: empirical coordinates for the crystallisation PT-estimations. GFF”, 119 (1997 (55–60.
[37] Burnham, C.W., Magmas and hydrothermal fluids, in Barnes, H.L., (ed.), “Geochemistry of Hydrothermal Ore Deposits”, Second Edition: Wiley, New York, (1979) 71-136.
[38] Richards, J.P., “The Porgera gold deposit, Papua New Guinea: geology, geochemistry and geochronology”, Ph.D thesis, Australian National University, 111 (1990).
[39] Le Bas, M.J., “The role of aluminum in igneous clinopyroxenes with relation to their parentage”, American Journal of Science, 260(4) (1962) 267-288.
[40] Jiménez-Munt, I., Fernàndez, M., Saura, E., Vergés, J., Garcia- Castellanos, D., 2012. 3-D lithospheric structure and regional/residual Bouguer anomalies in the Arabia–Eurasia collision (Iran). Geophys. J. Int. 190, 1311–1324.
[41] Shelley, D., “Igneous and Metamorphic Rocks under the Microscope. Chapman and Hall, London”, 445 (1993).