Geochemistry, petrogenesis and petrology of intrusive rocks in Shadan gold deposit, SW Birjand, Eastern Iran

Document Type : Research Paper

Authors

School of Geology, College of Science, University of Tehran, Tehran, Iran.

Abstract

Shadan gold (+copper) deposit in the Lut block, east of Iran, comprises Eocene to Oligocene intrusive and subvolcanic rocks with intermediate to felsic composition, which have intruded into Eocene volcanic- pyroclastic rocks. Shadan intrusive rocks range from granodiorite, quartz monzonite, and diorite to micro-gabbrodiorite. Geochemical data indicate that Shadan intrusive rocks are I-type, metaluminous to peraluminous, belonging to the calc-alkaline to high-potassic calc-alkaline magmatic series. Rare earth elements (REE) and trace elements patterns of Shadan rocks display enrichment in light rare earth elements (LREE) and large ion lithophile elements (LILE) relative to heavy rare earth elements (HREE) and high field strength elements (HFSE). The main hydrothermal alteration types contain quartz-carbonate, propylitic, argillic, phyllic and potassic, which affected the rocks in varying degrees. According to tectonomagmatic discrimination diagrams, all rock samples display evidence of a volcanic arc, which was formed at an active continental margin. Based on Nb/Y vs. Rb/Y ratio, Shadan rock samples experienced subduction zone enrichment and crustal contamination. According to Nb/Zr vs. Nb/Ba ratio, source region of the Shadan intrusive and subvolcanic rocks are attributed to the subcontinental lithosphere source. Th/Yb versus Nb/Yb diagram shows a separation between Shadan samples and MORB-OIB arrays,possibly due to crustal contamination and the mobility of Th during subduction. La vs. La/Yb ratio reveals that partial melting played a significant role in the formation of Shadan rocks.

Keywords

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Article Title [Persian]

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Arjmandzadeh, R., Karimpour, M.H., Mazaheri, S.A., Santos, J.F., Medina, J.M., Homam, S.M., 2011.
Two-sided asymmetric subduction; implications for tectonomagmatic and metallogenic evolution of
the Lut Block, eastern Iran. Journal of Economic Geology 1(3): 1-14.
Askren, D.R., Roden, M.F., Whitney, J.A., 1997. Petrogenesis of Tertiary andesite lava flows
interlayered with large-volume felsic ash-flow tuffs of the western USA. Journal of Petrology 38(8):
1021-1046.
Berberian, M., King, G.C.P., 1981. Towards a paleogeography and tectonic evolution of Iran. Canadian
journal of earth sciences 18(2): 210-265.
Boynton, W.V., 1984. Cosmochemistry of the rare earth elements: meteorite studies. In Developments
Geopersia 2023, 13(1): 33-48 47
in geochemistry 2:63-114.
Camp, V.E., Griffis, R.J., 1982. Character, genesis and tectonic setting of igneous rocks in the Sistan
suture zone, eastern Iran. Lithos 15(3): 221-239.
Chappell, B.W., White, A.J., 2001. Two contrasting granite types: 25 years later. Australian journal of
earth sciences 48(4): 489-499.
Dai, L.Q., Zhao, Z.F., Zheng, Y.F. and Zhang, J., 2015. Source and magma mixing processes in
continental subduction factory: Geochemical evidence from postcollisional mafic igneous rocks in
the D abie orogen. Geochemistry, Geophysics, Geosystems, 16(3), pp.659-680.
Darvishzadeh, A., 2004. Geology of Iran: stratigraphy, tectonic, metamorphism, and magmatism. Amir
kabir, Tehran.
Harker, A., 1909. The natural history of igneous rocks. Methuen and Company, London, 344p
Hooper, P.R., Hawkesworth, C.J., 1993. Isotopic and geochemical constraints on the origin and
evolution of the Columbia River Basalt. Journal of Petrology 34(6): 1203-1246. h
Karimpour, M.H., Malekzadeh, A., Hidareian, M.R. and Askari, A., 2007. Mineralization, alteration and
geochemistry of Hired gold-tin prospecting area, South Khorasan province. Iran. J. Crystalloger.
Miner., 15(1), pp.67-90.
Karimpour, M.H., Stern, C., Farmer, L., Saadat, S., 2011. Review of age, Rb-Sr geochemistry and
petrogenesis of Jurassic to Quaternary igneous rocks in Lut Block, Eastern Iran. Geopersia 1(1): 19-54.
Liu, B., Ma, C.Q., Guo, Y.H., Xiong, F.H., Guo, P. and Zhang, X., 2016. Petrogenesis and tectonic
implications of Triassic mafic complexes with MORB/OIB affinities from the western Garzê-Litang
ophiolitic mélange, central Tibetan Plateau. Lithos, 260: 253-267.
Mahdavi, P., Jafari Rad, A., Heuss-Aßbichler, S., Lotfi, M. and Nezafati, N., 2020. Geology,
mineralogy, and fluids inclusion studies in Shadan copper-gold deposit, Southern Khorasan.
Geopersia, 10(2): 263-275.
Malekzadeh Shafaroudi, A. and Karimpour, M.H., 2011. Zircon U-Pb dating of Maherabad porphyry
copper-gold prospect area: evidence for a late Eocene porphyry-related metallogenic epoch in east
of Iran. Journal of Economic Geology, 3(1): 41-60.
Malekzadeh, S.A., Karimpour, M.H. and Mazaheri, S.A., 2010. Rb–Sr and Sm–Nd isotopic
compositions and Petrogenesis of ore-related intrusive rocks of gold-rich porphyry copper
Maherabad prospect area (north of Hanich), east of Iran.
Modabberi, S., Namayandeh, A., Setti, M., López-Galindo, A., 2019. Genesis of the Eastern Iranian
bentonite deposits. Applied Clay Science 168: 56-67.
Omidianfar, S., Monsef, I., Rahgoshay, M., Zheng, J., Cousens, B., 2020. The middle Eocene high-K
magmatism in Eastern Iran Magmatic Belt: constraints from U-Pb zircon geochronology and Sr-Nd
isotopic ratios. International Geology Review 62(13-14): 1751-1768.
Pang, K.N., Chung, S.L., Zarrinkoub, M.H., Khatib, M.M., Mohammadi, S.S., Chiu, H.Y., Chu, C.H.,
Lee, H.Y., Lo, C.H., 2013. Eocene–Oligocene post-collisional magmatism in the Lut–Sistan region,
eastern Iran: Magma genesis and tectonic implications. Lithos 180: 234-251.
Pearce, J.A., 2008. Geochemical fingerprinting of oceanic basalts with applications to ophiolite
classification and the search for Archean oceanic crust. Lithos 100(1-4): 14-48.
Pearce, J.A., Harris, N.B., Tindle, A.G., 1984. Trace element discrimination diagrams for the tectonic
interpretation of granitic rocks. Journal of petrology 25(4): 956-983.
Peccerillo, A., Taylor, S.R., 1976. Geochemistry of Eocene calc-alkaline volcanic rocks from the
Kastamonu area, northern Turkey. Contributions to mineralogy and petrology 58(1): 63-81.
Richards, J.P., 2015. Tectonic, magmatic, and metallogenic evolution of the Tethyan orogen: From
subduction to collision. Ore Geology Reviews 70: 323-345.
Richards, J.P., Sholeh, A., 2016. The Tethyan tectonic history and Cu-Au metallogeny of Iran. Tectonics
and Metallogeny of the Tethyan Orogenic Belt. Society of Economic Geologists, Special Publication
19: 193-212.
Richards, J.P., Spell, T., Rameh, E., Razique, A. and Fletcher, T., 2012. High Sr/Y magmas reflect arc
maturity, high magmatic water content, and porphyry Cu±Mo±Au potential: Examples from the
Tethyan arcs of central and eastern Iran and western Pakistan. Economic geology, 107(2): 295-332.
Rollinson, H., Pease, V., 2021. Using Geochemical Data: To Understand Geological Processes.
Cambridge University Press.
Rollinson, H.R., 1993. Using Geochemical Data: Evaluation, Presentation, Interpretation. Longman
48 Yazdi et al.
Scientific and Technical, London, p. 352.
Rudnick, R.L., Fountain, D.M., 1995. Nature and composition of the continental crust: a lower crustal
perspective. Reviews of geophysics 33(3): 267-309.
Saccani, E., Delavari, M., Beccaluva, L., Amini, S., 2010. Petrological and geochemical constraints on
the origin of the Nehbandan ophiolitic complex (eastern Iran): Implication for the evolution of the
Sistan Ocean. Lithos 117(1-4): 209-228.
Samiee, S., Ghaderi, M. and Zirjanizadeh, S., 2019. Geochemistry, Fluid Inclusion and Sulfur Isotopes
Studies of Hydrothermal Breccia Gold Mineralization in the Khunik Area, Khorasan Jonoubi
Province (Iran). Journal of Economic Geology, 11(3): 473-495.
Schandl, E.S., Gorton, M.P., 2002. Application of high field strength elements to discriminate tectonic
settings in VMS environments. Economic geology 97(3): 629-642.
Shafaroudi, A.M., Karimpour, M.H. and Stern, C.R., 2015. The Khopik porphyry copper prospect, Lut
Block, Eastern Iran: geology, alteration and mineralization, fluid inclusion, and oxygen isotope
studies. Ore Geology Reviews, 65: 522-544.
Stöcklin, J., 1968. Structural history and tectonics of Iran: a review. AAPG bulletin 52(7): 1229-1258.
Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalts: implications
for mantle composition and processes. Geological Society, London, Special Publications 42(1): 313-
345.
Tarkian, M., Lotfi, M., & Baumann, A., 1983. Tectonic, magmatism and the formation of mineral
deposits in the central Lut, east Iran.
Temel, A., Gündoğdu, M.N., Gourgaud, A., 1998. Petrological and geochemical characteristics of
Cenozoic high-K calc-alkaline volcanism in Konya, Central Anatolia, Turkey. Journal of
volcanology and geothermal research 85(1-4): 327-354.
Tirrul, R., Bell, I.R., Griffis, R.J., Camp, V.E., 1983. The Sistan suture zone of eastern Iran. Geological
Society of America Bulletin 94(1): 134-150.
Vahdati-Daneshmand, F., Eftekhar-Nezhad, J., 1991. Geological map of Birjand Scale 1:250000.
Geological Survey of Iran.
Vassigh, H., Soheili, M., 1975. Geological map of Sar-E-chah-E-Shur Scale 1:100000. Geological
Survey of Iran.
Verdel, C., Wernicke, B.P., Hassanzadeh, J., Guest, B., 2011. A Paleogene extensional arc flare‐up in
Iran. Tectonics 30(3).
Wang, Q., Wyman, D.A., Xu, J., Jian, P., Zhao, Z., Li, C., Xu, W., Ma, J., He, B., 2007. Early Cretaceous
adakitic granites in the Northern Dabie Complex, central China: implications for partial melting and
delamination of thickened lower crust. Geochimica et cosmochimica acta 71(10): 2609-2636.
Zarrinkoub, M.H., Pang, K.N., Chung, S.L., Khatib, M.M., Mohammadi, S.S., Chiu, H.Y., Lee, H.Y.,
2012. Zircon U–Pb age and geochemical constraints on the origin of the Birjand ophiolite, Sistan
suture zone, eastern Iran. Lithos 154: 392-405.
Zhao, Z.F., Dai, L.Q. and Zheng, Y.F., 2013. Postcollisional mafic igneous rocks record crust-mantle
interaction during continental deep subduction. Scientific Reports, 3(1): 1-6.