Document Type : Original Research Paper


1 M. Sc., Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran

2 Associated Professor, Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran

3 Assistant Professor, Department of Geology, Faculty of Science, Islamic Azad University, Miyane Branch, Miyane, Iran

4 Assistant Professor, Department of Geochemistry, Faculty of Earth Sciences, Kharazmi University, Tehran, Iran


The Chomalu Polymetallic deposit is located in western part of Alborz magmatic belt (Alborz-Azarbaijan) and central part of Tarom-Hashtjin metallogenic province. Eocene volcanic settings in the Chomalu deposit consist of basic rocks (olivinebasalt), intermediate (andesite basalt, andesite to trachyandesite) and acidic rocks (dacite to rhyolite) which is intruded by quartz monzodiorite, monzosyenite and quartz monzonite intrusive rocks of Eocene. The main texture of volcanic rocks is more porphyritic. Olivine and plagioclase are the main phenocrysts in the olivinebasalt, andesite rocks compose of plagioclase and clinopyroxene and dacite to rhyolite consist of plagioclase, alkali feldspar and quartz. On the basis of AFM diagram, Chomalu volcanic rocks located in the high- K calc- alkaline to shoshonitic affinities in relation to subduction zone magmatism. Primitive mantle-normalized of volcanic rocks indicate that LILE enrichment and HFSE depletion in consistent with subduction zone magmatism. Chondrite-normalized REE patterns show LREE/HREE enrichment. Geochemical results suggesting primary source magmas source for volcanic rocks were generated by partial melting of the metasomatized lithospheric mantle-wedge in relation to subduction arc and were subsequently affected by both fractional crystallization and crustal contamination during magmatic evolution.


Main Subjects

Aghazadeh, M., Castro, A., Omran, N.R., Emami, M.H., Moinvaziri, H. and Badrzadeh, Z., 2010- The gabbro (shoshonitic)–monzonite–granodiorite association of Khankandi pluton, Alborz Mountains, NW Iran. Journal of Asian Earth Sciences 38, 199–219,
Aghazadeh, M., Castro, A., Badrzadeh, Z. and Vogt, K., 2011- Post-collisional polycyclic plutonism from the Zagros hinterland: The Shaivar Dagh plutonic complex, Alborz belt, Iran. Geological Magazine 148 (5–6), 980.1008,
Alavi, M., 1991- Sedimentary and structural characteristic of the Paleo-Tethyan remnants in North Eastern Iran, Bull. Geol. Soc. Am,103, 983-992,<0983:SASCOT>2.3.CO;2.
Asiabanha, A. and Foden, J., 2012- Post-collisional transition from an extensional volcanosedimentary basin to a continental arc in the Alborz Ranges, N-Iran. Lithos 148, 98–111,
Azizi, H. and Moinevaziri, H., 2009- Review of the tectonic setting of Cretaceous to Quaternary volcanism in northwestern Iran, Journal of Geodynamics 47, 167–179,
Chappell, B.W. and White, A.J.R., 1992- I and S-type Granites in the Lachlan Fold Belt. Transactions of the Royal Society of Edinburgh: Earth Sciences 83, 1-26,
Castro, A., Aghazadeh, M., Badrzadeh, Z. and Chichorro, M., 2013- Late Eocene–Oligocene post-collisional monzonitic intrusions from the Alborz magmatic belt, NW Iran. An example of monzonite magma generation from a metasomatized mantle source, Lithos, Volumes 180-181, Pages 109-127,
DePaolo, D. J. and Daley, E. E., 2000- Neodymium isotopes in basalts of the southwest basin and range and lithospheric thinning during continental extension. Chemical Geology, 169, 157–185,
Ghasemi Siani, M., Lentz, D.R., Nazarian M., 2020. Geochemistry of igneous rocks associated with mineral deposits in the Tarom-Hashtjin metallogenic province, NW Iran: An analysis of the controls on epithermal and related porphyry-style mineralization. Ore Geol. Rev., 126,
Ghasemi Siani, M., Mehrabi, B., Azizi, H., Wilkinson, C.M. and Ganerod, M., 2015- Geochemistry and geochronology of the volcano-plutonic rocks associated with the Glojeh epithermal gold mineralization, NW Iran. Open Geosci. 7, 207–222,
Gorton, M. P. and Schandl, E. S., 2000- From continents to island arcs: A geochemical index of tectonic setting for arc- related and within- plate felsic to intermediate volcanic rocks. Canadian Mineralogist 38: 1065- 1073,
Harris N., B W, Pearce J. A, Tindle A. G., 1986- Geochemical characteristics of collision- zone magmatism. In: Coward M P, Ries A C (eds) Collision Tectonics. Geological Society London Special Publication 19, pp 67-81,
Irvine, T.N. and Baragar W.R.A., 1971- A guide to the Chemical classification of the common volcanic rocks. Canadian jounal of earth science 8: 523-548,
Kuscu, G. G. and Geneli, F., 2010- Review of post-collisional volcanism in the central Anatolian volcanic province Turkey, with special reference to the Tepekoy volcanic complex. International Journal of Earth Sciences 99(3): 593-621,
Kouhestani, H., Azimzadeh, A.M., Mokhtari, M.A.A. and Ebrahimi, M., 2017- Mineralization and fluid evolution of epithermal base metal veins from the Aqkand deposit, NW Iran. J. Miner. Geochem. 194, 139–155,
Kouhestani, H., Mokhtari, M, A. A., Changb, Z. and Johnson, C. A., 2018- Intermediate sulfidation type base metal mineralization at Aliabad-Khanchy, Tarom-Hashtjin metallogenic belt, NW Iran, Ore Geology Reviews 93, Volume 93, 1–18,
Leat, P. T., Pearce, J. A., Barker, P. F., Millar, I. L., Barry, T. L. and Larter, R. D., 2004- Magma genesis and mantle flow at a subducting slab edge: The South Sandwich arc- basin system. Earth and Planetary Science Letters 227: 17- 35,
Le Bas, M.J., Le Maître, R.W., Streckeisen, A.and Zanettin, B., 1986- A chemical classification of volcanic rocks based on the total alkali-silica diagram. Journal of Petrology, 27(3): 745–750,
Machado, A. T., Chemale, Jr. F., Conceicao, R. V., Kawaskita, K., Morata, D., Oteıza, O. and Schmus, W. R. V., 2005- Modeling of subduction components in the Genesis of the Meso-Cenozoic igneous rocks from the South Shetland Arc, Antarctica. Lithos 82(3-4): 435– 453,
Mehrabi, B. and Ghasemi Siani, M., 2012- Intermediate sulfidation epithermal Pb-Zn-Cu (±Ag-Au) mineralization at Cheshmeh Hafez deposit, Semnan Province, Iran. Journal of Geological Society of India 80, 563–578,
Mehrabi, B., Ghasemi Siani, M. and Tale Fazel, E., 2015- Structural Control on Epithermal Mineralization in the Troud-Chah Shirin Belt Using Point Pattern and Fry Analyses, North of Iran. Geotectonics 49 (4), 317–328,
Mehrabi, B., Ghasemi Siani, M., Goldfarb, R., Azizi, H., Ganerod, N. and Marsh, E.E., 2016- Mineral assemblages, fluid evolution, and genesis of polymetallic epithermal veins, Glojeh district, NW Iran. Ore Geology Review 78, 41–57,
Mohamed, F. H., Moghazi, A. M. and Hassanen, M. A., 2000- Geochemistry, Petrogenesis and tectonic setting of late Neoproterozoic Dokhan- type volcanic rocks in the Fatira area, eastern Egypt. International Journal of Earth Science 88(4): 764-777,
Nabatian, Gh., Ghaderi, M., Corfu, F., Neubauer, F., Bernroider, M., Prokofiev, V. and Honarmand, M., 2014- Geology, alteration, age and origin of iron oxide–apatite deposits in Upper Eocene quartz monzonite, Zanjan district, NW Iran. Mineralium Deposita, 49, 217–234,
Orozco-Esquivel, T., Petrone, C. M., Ferrari, L., Tagami, T. and Manetti, P., 2007- Geochemical and isotopic variability in lavas from the eastern Trans-Mexican volcanic belt: slab detachment in a subduction zone with varying dip. Lithos 93: 149-174,
Peccerillo, A. and Taylor, S.R., 1976- Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastomonon area, northern Turkey. Contribution mineral petrol. 58: 63-81,
Pearce T.H., Gorman B.E. and Birkett T.C., 1977- The relationship between major element chemistry and tectonic environment of basic and intermediate volcaniv rocks. Earth Planet. Sci. Lett., 36, 121-132,
Richards, J.P., 2015. Tectonic, magmatic, and metallogenic evolution of the Tethyan orogen: From subduction to collision. Ore Geology Review 70, 323–345,
Rollinson, H. R., 1993- Using geochemical data: evolution, presentation, interpretation. London, UK, 652 p,
Shamanian, G.H., Hedenquist, J.W., Hattori, K.H. and Hassanzadeh, J., 2004 -The Gandy and Abolhassani epithermal prospects in the Alborz magmatic arc, Semnan Province, northern Iran. Economic Geology 99, 691–712,
Sun, S.S. and McDonough, W.F., 1989- Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In: Saunders AD, Norry MJ (eds) Magmatism in the ocean basins. Geological Society of London Special Publications 42, 313-345,
Saiedi, A., Mokhtari, M. A. A. and Kouhestani, H., 2018- Petrology and geochemistry of intrusive rocks at Khanchay- Aliabad region (Tarom sub-zone, East of Zanjan). Iranian Journal of Petrology 33: 207-229 (in Persain),
Seghedi, I., Downes, H., Pecskay, Z., Thirlwall, M.F., Szakacs, A., Prychodko, M. and Mattey, D., 2001- Magmagenesis in a subductionrelated post-collisional volcanic arc segment: The Ukrainian Carpathians. Lithos 57(4): 237– 262,
Tale Fazel, E., Mehrabi, M. and Ghasemi Siani, M., 2019- Epithermal systems of the Torud–Chah Shirin district, northern Iran: Ore-fluid evolution and geodynamic setting. Ore Geology Review 109, 253–275,
Temel, A., Gondogdu, M.N. and Gourgaud, A., 1998- Petrological and geochemical characteristics of Cenozoic high K-calk alkaline volcanism in Konya, Central Anatolia, Turkey. Journal of Volcanology and Geothermal Research 85: 327-357,
Verdel, C., Wernicke, B.P., Hassanzadeh, J. and Guest, B., 2011- A Paleogene extensional arc flare-up in Iran. Tectonics 30, 
TC3008, 1–20,
Wang, K. L. and Chung, S. L., 2004- Geochemical constraints for the genesis of post-collisional magmatism and the geodynamic evolution of the northern Taiwan region. Journal of Petrology 45: 975-1011,
Whitney, D. and Evans, B. W., 2010- Abbreviations for names of rock-forming minerals. American Mineralogist 95, 185–187,
Wilson, M., 1989- Igneous petrogenesis a global tectonic approach. Unwin Hymen, London,
Winchester, J. A. and Floyd, P.A., 1977- Geochemical discrimination of different magma series anr their differentiation products using immobile element. Chem. Geol., 20, 325-343,
Wood, D.A., 1980, “The application of a Th-Hf-Ta diagram to problems of tectonomagmatic classification and to establishing the nature of crustal contamination of basaltic lavas of the British Tertiary Volcanic Province”, Earth and Planetary Science Letters, 50: P.11-30.
Yasami, N., Ghaderi, M., Madanipour, S. and Taghilou, B., 2017- Structural control on overprinting highsulfidation epithermal on porphyry mineralization in the Chodarchay deposit, northwestern Iran. Ore Geol. Rev. 86, 212–224,
Yang, W. and Li, S., 2008- Geochronology and geochemistry of the Mesozoic volcanic rocks in Western Liaoning: Implications for lithospheric thinning of the North China Craton. Lithos 102 (1-3): 88–117,