Petrology of porphyritic quartz monzodiorite stock and Eocene dykes with adakitic nature from SW of Jandaq (NE of Isfahan province); Evidence of oceanic crust subduction around the Central-East Iranian Microcontinent

Document Type : Research Article

Authors

• Ahamad Jamshidzaei
• Ghodrat Torabi

Isfahan

10.22067/econg.v10i2.63996

Abstract

Introduction
The “adakite” term was used for the first time by Defant and Drummond (1990) to display Cenozoic arcs igneous rocks with intermediate composition (SiO2> 56 wt.%), which were produced by partial melting of subducted oceanic crust. The adakites are series of intermediate to acidic rocks, with composition range from hornblende-andesite to dacite and rhyolite; and basaltic composition are lacking. In adakitic magmas, phenocrysts are mainly plagioclase, hornblende and biotite; while orthopyroxene and clinopyroxene phenocrysts are known only in mafic andesites (Calmus et al., 2003). Geochemically, adakites are identified with SiO2> 56 wt.%, Al2O3> 15 wt.%, MgO< 3 wt.%, Sr> 400 ppm and enriched LILE and LREE and depleted Y and HREE (Y< 18 ppm, Yb< 1.9 ppm) and high ratios of Sr/Y> 40 and La/Yb> 20 (Castillo, 2006 and Castillo, 2012). By using geochemical data, adakites were classified into high silica adakites (HSA, SiO2> 60 wt.%) and low silica adakites (LSA, SiO2< 60 wt.%) main groups. The high silica adakites were produced by partial melting of subducted oceanic crust basalts and the resulting melts also interact with peridotite during their ascent through the mantle wedge. While, low silica adakites were produced by melting of mantle peridotite that were metasomatized by melts resulting from slab (Martin and Moyen, 2002).
The intrusion bodies with porphyritic texture has been studied and reported in different areas (e.g. Lan et al., 2012; Zhang et al., 2015). This intrusion bodies are often in a stock shape and the texture is porphyritic due to fast crystallization.
The study area (Kuh-e- Godar-e Siah) is located in southwest of Jandaq (northeast of Isfahan province) and northwest of Central-East Iranian Microcontinent. The quartz monzodiorite intrusion with stock shape cross cutting by Eocene dykes swarm with trachy andesitic composition. In this paper, the petrology and chemical characteristics of quartz monzodiorites and trachy andesitic dykes are discussed.
 
Material and methods
The chemical compositions of minerals from quartz monzodiorites and dykes were conducted by a JEOL JXA-8600 (WDS) electron probe microanalyzer (EPMA) at the Kanazawa University, Japan. Analyses were performed by an accelerating voltage of 20 kV and a beam current of 20 nA. The Fe2+ and Fe3+ contents of minerals were calculated by assuming mineral stoichiometry. The Fe2+# and Mg# parameters of minerals are Fe2+/(Fe2++Mg) and Mg/(Mg+Fe2+) atomic ratios, respectively. Representative chemical analyses of the minerals are listed in Table 1 and 2. To obtain whole rock chemical data, eighteen samples of the studied rocks were analyzed at the ALS-Mineral Company of Canada, by a combination of inductively coupled plasma spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) methods. The whole rocks geochemical data are presented in Table 3 and 4. Also, X-ray diffraction analyses were carried out in order to typify the K-feldspar mineral using an XRD D8 ADVANCE, Bruker machine, at the Central Laboratory of the University of Isfahan. The FeO and Fe2O3 concentrations are recalculated from Fe2O3*, using recommended ratios of Middlemost (1989). Mineral abbreviations are from Whitney and Evans (2010).
 
Results and discussion
The main texture in quartz monzodiorites is porphyritic; and Eocene dykes are granular, intergranular and porphyritic in texture. The quartz monzodiorites consist of plagioclase (albite), sanidine, quartz, biotite, muscovite, chlorite, magnetite, calcite and apatite. The minerals in trachy andesitic dykes are plagioclase (andesine and labradorite), clinopyroxene (diopside and augite), sanidine, phlogopite, quartz, amphibole, magnetite, calcite and apatite. The chondrite-normalized REE patterns and primitive mantle-normalized multi-elemental diagram of the quartz monzodiorites and trachy andesitic dykes show enrichment in LREE and LILEs and depletion in HFSEs such as Ta, Nb and Ti. There is no evident positive or negative anomaly of Eu. Petrographical and geochemical characteristics of quartz monzodiorites and trachy andesitic dykes show that these rocks have been derived from different sources. The quartz monzodiorites have high content of La/Yb= 17.49-41.89, SiO2= 64.60-68.80 wt.%, Sr= 434-1855 ppm, Sr/Y= 53.58-168.63 and low content of MgO= 0.16-1.10 wt.%, Y< 11 ppm and Yb< 0.95 ppm that show characteristics of high silica adakites which have been produced by melting of subducted oceanic crust. The trachy andesitic dykes have La/Yb= 33.45-59.76, SiO2= 53.40-57.60 wt.%, Sr= 859-2050 ppm, Sr/Y= 50.82-125, MgO= 1.93-4.53 wt.%, Y< 13.8 ppm and Yb< 1.14 ppm, which display characteristics related to low silica adakites, produced by melting of metasomatized mantle peridotite.
Acknowledgments
The authors thank the University of Isfahan for financial supports.
 
References
Calmus, T., Aguillon-Robles, A., Maury, R.C., Bellon, H., Benoit, M., Cotten, J., Bourgois, J. and Michaud, F., 2003. Spatial and temporal evolution of basalts and magnesian andesites (“bajaites”) from Baja California, Mexico: the role of slab melts. Lithos, 66(1): 77–105.
Castillo, P.R., 2006. An overview of adakite petrogenesis. Chinese Science Bulletin, 51(3): 257–268.
Castillo, P.R., 2012. Adakite petrogenesis. Lithos, 134(5): 304–316.
Defant, M.J. and Drummond, M.S., 1990. Derivation of some modern arc magmas by melting of young subducted lithosphere. Nature, 347(6294): 662–665.
Lan, T.G., Fan, H.R., Santosh, M., Hu, F.F., Yang, K.F., Yang, Y.H. and Liu, Y., 2012. Early Jurassic high-K calc-alkaline and shoshonitic rocks from the Tongshi intrusive complex, eastern North China Craton: implication for crust–mantle interaction and post-collisional magmatism. Lithos, 140(2): 183–199.
Martin, H. and Moyen, J.F., 2002. Secular changes in tonalite-trondhjemite-granodiorite composition as markers of the progressive cooling of earth. Geology, 30(4): 319–322.
Middlemost, E.A., 1989. Iron oxidation ratios, norms and the classification of volcanic rocks. Chemical Geology, 77(1): 19–26.
Whitney, D.L. and Evans, B.W., 2010. Abbreviations for names of rock-forming minerals. American Mineralogist, 95(1): 185–187.
Zhang, J.Q., Li, S.R., Santosh, M., Wang, J.Z. and Li, Q., 2015. Mineral chemistry of high-Mg diorites and skarn in the Han-Xing Iron deposits of South Taihang Mountains, China: Constraints on mineralization process. Ore Geology Reviews, 64(1): 200–214.

Keywords

• Quartz monzodiorite
• Trachy andesite
• subduction
• Adakite
• eocene
• Central-East Iranian Microcontinent

20.1001.1.20087306.1397.10.2.3.8

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References

Ahmadian, J., Sarjoughian, F., Lentz, D., Esna-Ashari, A., Murata, M. and Ozawa, H., 2016. Eocene K-rich adakitic rocks in the Central Iran: Implications for evaluating its Cu–Au– Mo metallogenic potential. Ore Geology Reviews, 72(1): 323–342.

Aistov, L., Melnikov, B., Krivyakin, B. and Morozov, L., 1984. Geology of the Khur Area (Central Iran). Geological Survey of Iran, Tehran, Report 20, 132 pp.

Arndt, N.T, 2008. Komatiite. Cambridge University Press, Cambridge, 467 pp.

Calmus, T., Aguillon-Robles, A., Maury, R.C., Bellon, H., Benoit, M., Cotten, J., Bourgois, J. and Michaud, F., 2003. Spatial and temporal evolution of basalts and magnesian andesites (“bajaites”) from Baja California, Mexico: the role of slab melts. Lithos, 66(1): 77–105.

Castillo, P.R., 2006. An overview of adakite petrogenesis. Chinese Science Bulletin, 51(3): 257–268.

Castillo, P.R., 2012. Adakite petrogenesis. Lithos, 134(5): 304–316.

Condie, K.C., 1989. Geochemical changes in basalts and andesites across the Archean-Proterozoic boundary: identification and significance. Lithos, 23(1-2): 1-18.

Defant, M.J. and Drummond, M.S., 1990. Derivation of some modern arc magmas by melting of young subducted lithosphere. Nature, 347(6294): 662–665.

Gill, J.B., 1981. Orogenic andesite and plate tectonics. Springer, Berlin, 390 pp.

Grove, T.L., Baker, M.B., Price, R.C., Parman, S.W., Elkin-Tanton, L.T., Chatterjee, N. and Muntener, O., 2005. Magnesian andesite and dacite lavas from Mt. Shasta, northern California: products of fractional crystallization of H2O-rich mantle melts. Contributions to Mineralogy and Petrology, 148(5): 542–565.

Hofmann, A.W., Jochum, K.P., Seufert, M. and White, W.M., 1986. Nb and Pb in oceanic basalts: new constraints on mantle evolution. Earth and Planetary Science Letters, 79(1-2): 33–45.

Irvine, T. and Baragar, W., 1971. A guide to the chemical classification of the common volcanic rocks. Canadian Journal of Earth Sciences, 8(5): 523–548.

Lan, T.G., Fan, H.R., Santosh, M., Hu, F.F., Yang, K.F., Yang, Y.H. and Liu, Y., 2012. Early Jurassic high-K calc-alkaline and shoshonitic rocks from the Tongshi intrusive complex, eastern North China Craton: implication for crust–mantle interaction and post-collisional magmatism. Lithos, 140(2): 183–199.

Le Maitre, R.W., 1989. A classification of igneous rocks and glossary of terms, Recommendations of the IUGS Subcommission on the Systematics of Igneous Rocks. Blackwell, Oxford, 193 pp.

Le Maitre, R.W., 2002. Igneous Rocks: A Classification and Glossary of Terms. Recommendations of the International Union of Geological Sciences, Subcommission on the Systematics of Igneous Rocks. Cambridge University Press, Cambridge, 254 pp.

Macpherson, C.G., Dreher, S.T. and Thirlwall, M.F., 2006. Adakites without slab melting: high pressure differentiation of island arc magma, Mindanao, the Philippines. Earth and Planetary Science Letters, 243(3): 581–593.

Mahmoodabadi, L., 2009. Petrography and petrology Eocene Volcanics from Southwest of Jandaq (Northeast Isfahan). M.Sc. Thesis, University of Isfahan, Isfahan, Iran, 220 pp. (in Persian with English abstract)

Martin, H., 1999. The adakitic magmas: modern analogues of Archaean granitoids. Lithos, 46(3): 411–429.

Martin, H. and Moyen, J.F., 2002. Secular changes in tonalite-trondhjemite-granodiorite composition as markers of the progressive cooling of earth. Geology, 30(4): 319–322.

Martin, H., Smithies, R.H., Rapp, R., Moyen, J.F. and Champion, D., 2005. An overview of adakite, tonalite–trondhjemite–granodiorite (TTG), and sanukitoid: relationships and some implications for crustal evolution. Lithos, 79(1): 1–24.

McDonough, W.F. and Sun, S.S., 1995. The composition of the Earth. Chemical Geology, 120(3–4): 223–253.

Middlemost, E.A., 1989. Iron oxidation ratios, norms and the classification of volcanic rocks. Chemical Geology, 77(1): 19–26.

Moyen, J.F., 2009. High Sr/Y and La/Yb ratios: the meaning of the “adakitic signature”. Lithos, 112(3): 556–574.

Nazari, G.H. and Torabi, G., 2017. Petrogenetic processes, crystallization conditions and nature of the Lower- Oligocene calc-alkaline spessartitic lamprophyres from Kal-e-kafi area (East of Anarak, Isfahan province). Journal of Economic Geology, 9(2): 375–395. (in Persian with English abstract)

Nosouhian, N., Torabi, G. and Arai, S., 2016. Late Cretaceous dacitic dykes swarm from Central Iran, a trace for amphibolite melting in a subduction zone. Geotectonics, 50(3): 295–312.

Omrani, J., Agard, P., Whitechurch, H., Benoit, M., Prouteau, G. and Jolivet, L., 2008. Arc-magmatism and subduction history beneath the Zagros Mountains, Iran: A new report of adakites and geodynamic consequences. Lithos, 106(3–4): 380-398.

Pearce, J.A., Lippard, S.J. and Roberts, S., 1984. Characteristics and tectonic significance of supra-subduction zone ophiolites. In: B.P. Kokelaar and M.F. Howells (Editors), Marginal Basin Geology: Volcanic and Associated Sedimentary and Tectonic Processes in Modern and Ancient Marginal Basins. Geological Society of London Publications, Special Publication, 16, London, pp. 77-94.

Prouteau, G., Scaillet, B., Pichavant, M. and Maury, R.C., 2001. Evidence for mantle metasomatism by hydrous silicic melts derived from subducted oceanic crust. Nature, 410(6825): 197–200.

Rajabi, S. and Torabi, G., 2013. Mineralogy and geochemistry of xenoliths in the Eocene volcanic rocks from southwest of Jandaq. Journal of Economic Geology, 5(1): 65–82. (in Persian with English abstract)

Rapp, R.P. and Watson, E.B., 1995. Dehydration melting of metabasalt at 8–32 kbar: implications for continental growth and crust-mantle recycling. Journal of Petrology, 36(4): 891–931.

Reich, M., Parada, M.A., Palacios, C., Dietrich, A., Schultz, F. and Lehmann, B., 2003. Adakite-like signature of Late Miocene intrusions at the Los Pelambres giant porphyry copper deposit in the Andes of central Chile: metallogenic implications. Mineralium Deposita, 38(7): 876–885.

Rosu, E., Seghedi, I., Downes, H., Alderton, D.H.M., Szakacs, A., Pecskay, Panaiotu, C.E. and Nedelcu, L., 2004. Extension related Miocene calc-alkaline magmatism in the Apuseni Mountains, Romania: Origin of magmas. Schweizerische Mineralogische und Petrographische Mitteilungen, 84(1): 153–172.

Shirdashtzadeh, N., Torabi, G., Meisel, T., Arai, S., Bokhari, S.N.H., Samadi, R. and Gazel, E., 2014. Origin and evolution of metamorphosed mantle peridotites of Darreh Deh (Nain Ophiolite, Central Iran): implications for the Eastern Neo-Tethys evolution. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 273(1): 89–120.

Shirdashtzadeh, N., Torabi, G. and Samadi, R., 2017. Petrography and mineral chemistry of metamorphosed mantle peridotites of Nain Ophiolite (Central Iran). Journal of Economic Geology, 9(1): 57–72. (in Persian with English abstract)

Sun, S.S. and McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In: A.D. Saunders and M.J. Norry (Editors), Magmatism in the Ocean Basins. Geological Society of London Publications, Special Publication, 42, London, pp. 313-345.

Tabatabaei Manesh, S.M., Sharifi, M. and Romanko, A., 2010. P-T condition of the Jandagh metapelitic schists, Northeastern Isfahan Province, Iran. Petrology, 18(3): 308–317.

Tang, Y., Li, X., Xie, Y., Liu, L., Lan, T., Meffre, S. and Huang, C., 2017. Geochronology and geochemistry of late Jurassic adakitic intrusions and associated porphyry Mo–Cu deposit in the Tongcun area, east China: Implications for metallogenesis and tectonic setting. Ore Geology Reviews, 80(1): 289–308.

Torabi, G., 2009. Subduction-related Eocene shoshonites from the Cenozoic Urumieh-Dokhtar magmatic arc (Qaleh-Khargooshi area, West of the Yazd province, Iran). Turkish Journal of Earth Sciences, 18(4): 583–613.

Torabi, G., 2010. Early Oligocene alkaline lamprophyric dykes from the Jandaq area (Isfahan Province, Central Iran): Evidence of Central–East Iranian microcontinent confining oceanic crust subduction. Island Arc, 19(2): 277–291.

Torabi, G., 2011. Late Permian blueschist from Anarak ophiolite (Central Iran, Isfahan province), a mark of multi-suture closure of the Paleo-Tethys Ocean. Revista Mexicana de Ciencias Geologicas, 28(3): 544–554.

Torabi, G., 2012. Late Permian post‐ophiolitic trondhjemites from Central Iran: a mark of subduction role in growth of Paleozoic continental crust. Island Arc, 21(3): 215–229.

Vernon, R. H., 2004. A practical guide to rock microstructure. Cambridge University Press, Cambridge, 606 pp.

Wang, Q., Wyman, D.A., Xu, J., Wan, Y., Li, C., Zi, F., Jiang, Z., Qiu, H., Chu, Z., Zhao, Z. and Dong, Y., 2008. Triassic Nb-enriched basalts, magnesian andesites, and adakites of the Qiangtang terrane (Central Tibet): evidence for metasomatism by slab-derived melts in the mantle wedge. Contributions to Mineralogy and Petrology, 155(4): 473–490.

Whitney, D.L. and Evans, B.W., 2010. Abbreviations for names of rock-forming minerals. American Mineralogist, 95(1): 185–187.

Zhang, J.Q., Li, S.R., Santosh, M., Wang, J.Z. and Li, Q., 2015. Mineral chemistry of high-Mg diorites and skarn in the Han-Xing Iron deposits of South Taihang Mountains, China: Constraints on mineralization process. Ore Geology Reviews, 64(1): 200–214.

Zhu, A.C., Zhao, Z.D., Pan, G.T., Lee, H.Y., Kang, Z.Q., Liao, Z.L., Wang, L.Q., Li, G.M., Dong, G.C. and Liu, B., 2009. Early Cretaceous subduction-related adakite-like rocks of the Gangdese Belt, southern Tibet: products of slab melting and subsequent melt-peridotite interaction? Journal of Asian Earth