Petrography, Geochemistry and Petrogenesis of Volcanic Rocks, NW Ghonabad, Iran

Document Type : Research Article

Authors

• Sedigheh Zirjanizadeh ¹
• Mohammad Hassan Karimpour ²
• Khosrow Ebrahimi Nasrabadi ²
• Jose Francisco Santos ³

¹ Ferdowsi university of Mashhad

² Ferdowsi University of Mashhad

³ Aveiro

10.22067/econg.v8i1.48865

Abstract

Introduction
The study area is located in NW Gonabad, Razavi Khorasan Province, northern Lut block and eastern Iran north of the Lut Block. Magmatism in NW Gonabad produced plutonic and volcanic rock associations with varying geochemical compositions. These rocks are related to the Cenozoic magmatic rocks in Iran and belong to the Lut Block volcanic–plutonic belt. In this study, petrogenesis of volcanic units in northwest Gonabad was investigated.
The volcanic rocks are andesites/trachyandesites, rhyolites, dacites/ rhyodacites and pyroclastics.These rocks show porphyritic, trachytic and embayed textures in phenocrysts with plagioclase, sanidine and quartz (most notably in dacite and rhyolite), hornblende and rare biotite. The most important alteration zones are propylitic, silicification and argillic.Four kaolinite- bearing clay deposits have been located in areas affectedby hydrothermal alteration of Eocene rhyolite, dacite and rhyodacite.

Analytical techniques
Five samples were analyzed for major elements by wavelength dispersive X-ray fluorescence (XRF) and six samples were analyzed for trace elements using inductively coupled plasma-mass spectrometry (ICP-MS) in the Acme Laboratories, Vancouver (Canada).Sr and Nd isotopic compositions were determined for four whole-rock samples at the Laboratório de GeologiaIsotópica da Universidade de Aveiro, Portugal.

Results
Petrography. The rocks in this area are consist of trachyte, andesite/ trachyandesite, dacite/ rhyodacite, principally as ignimbrites and soft tuff. The textures of phenocrysts are mainly porphyritic, glomerophyric, trachytic and embayed textures in plagioclase, hornblende and biotite. The groundmasses consist of plagioclase and fine-grainedcrystals of hornblende. Plagioclase phenocrysts and microlitesare by far the most abundant textures in andesite - trachyandesites (>25% and in size from 0.01 to 0.1mm). Euhedral to subhedral hornblende phenocrysts areabundant (3-5%)and 0.1 to 0.6mmin size.
Trachyte is characterized by trachytic texture. Ninety percent of the rock consists of sanidine. In trachytes, 3 to 5% hornblende ( 0.3 mm) is replaced by carbonates. Rhyolites contain quartz, plagioclase, sanidine, and biotite phenocrysts in a microcrystalline to glassy groundmass. Rhyodacitehas phenocrysts, some glomerophyric, consisting of quartz, 2 to 3% (0.1-0.5 mm), plagioclase 7 to 10% (0.2- 0.8 mm), hornblende 5% and biotite 1%. Up to 15% of sanidineis altered to clay minerals. Crystal tuff and lithic-crystal tuff are distributed overa large area.
Using the Zr/TiO2 and Nb/Y diagram of Winchester and Fold (1977), samples are designated as rhyolite, dacite and sub-alkaline basalt. In the Co vs. Th diagram of Hastie et al. (2007), samples plot in the shoshonitic and high calc-alkaline, rhyolite, dacite and andesite-basalt fields.
The REE patterns and trace element contents of the volcanic samples show: (1) LREE/HREE enrichment ((La/Yb) N = 0.3 to 15.27), (2) Low negative Eu anomaly (ave.Eu*/Eu=0.2-0.85), (3) depletion in Ba, Sr, K2O, Zr and Ti (Lower continental crust-normalized spider diagram from Taylor and McLennan, 1985 and Chondrite-normalized diagram from Nakamura, 1974. Rhyolites show the most extreme negative Eu anomaly (Eu/Eu* = 0.2-0.3) compared with 0.65–0.85 for volcanic elsewhere and also show considerably differences in the contents of Rb,Sr,K,Ti,Zr,Hf,Ce. These differences are related to greater magmatic differentiation or derivation from the other sources. The Sr and Nd isotopic ratios of these volcanic rocks are: 87Sr/86Sr = 0.70699 to 0.71014 and 143Nd/144Nd =0.512144 to 0.512539. Assuming an age of 60 Ma, the initial 87Sr/86Sr ratios vary from 0.70671 to 0.71066 and initial 143Nd/144Nd values vary from 0.512098 0.51249 (εNdi = -9.1) to 0.51249 (εNdi = -1.4).In the εNdi versus (87Sr/86Sr)i diagram, the samples plot in the field typical of magmas that are of crustal origin or, at least, that underwent important processes of crustal assimilation/contamination.
Andesitic rocks displays lightly lower rangesof87Sr/86Sr (0.7067-0.7068) and εNdi values from -1.44 to -2.34, than rhyolite. Distinct Sr and Nd isotopic compositions are seen between rhyolitic rocks and andesitic rocks. The geochemical data suggest that the rhyolitic magmas probably represent the final differentiates of parental magmas, resulting from partial melting of mafic lower crust. Generally, the magmas from this area have low Sr (less than 400 ppm), high K2O/Na2O and negative Eu anomalies.

References
Hastie, A.R., Kerr, A.C., Pearce, J.A. and Mitchell, S.F., 2007. Classification of altered volcanic island arc rocks using immobile trace elements: development of the Th-Co discrimination diagram. Journal of Petrology, 48(12): 2341- 2357.
Nakamura, N., 1974. Determination of REE, Ba, Fe, Mg, Na, and K in carbonaceous and ordinary chondrites. Geochim, Cosmochim, Acta, 38(5): 757–775.
Taylor, S.R. and McLennan, S.M., 1985. The continental crust, its composition and evolution, an examination of the geochemical record preserved in sedimentary rocks. Blackwell, Oxford, 312 pp.
Winchester, J.A. and Floyd, P.A., 1977. Geochemical discrimination of different magma series and their differentiation products using immobile elements. Chemical Geology, 20(4): 325-343.

Keywords

• 87Sr/86Sri
• Geochemistry
• Volcanic rocks
• Lut block
• Eastern Iran

20.1001.1.20087306.1395.8.1.15.4

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References

Abdi, M. and Karimpour, M.H., 2013. Petrochemical characteristics and timing of Middle Eocene granitic magmatism in Kooh-Shah, Lute Block, Eastern Iran. Acta Geologica Sinica, 84(4) 1032–1044.

Aghanabati, A., 2004. Geology of Iran.Geological Survey of Iran, Tehran, 586 pp (in Persian).

Arjmandzadeh R. and Santos J.F., 2013. Sr–Nd isotope geochemistry and tectonomagmatic setting of the Dehsalm Cu–Mo porphyry mineralizing intrusives from Lut Block, eastern Iran. International Journal of Earth Science, 103(1): 123–140.

Arjmandzadeh R., Karimpour, M.H., Mazaheri, S.A., Santos, J.F., Medina, J.M. and Homam, S.M., 2011. Sr–Nd isotope geochemistry and petrogenesis of the Chah-Shaljami granitoids (Lut Block, Eastern Iran). Journal of Asian Earth Sciences, 41(3): 283–296.

Arsalan M. and Aslan Z., 2006.Mineralogy, petrography and whole-rock geochemistry of the Tertiary granitic intrusions in the Eastern Pontides, Turkey. Journal of Asian Earth Sciences, 27(2): 177-193.

Atherton, M.P. and Petford, N.,1993. Generation of sodium-rich magmas from newly under plated basaltic crust. Nature, 362:144–146.

Berberian, M., Jackson, J.A, Qorashi, M., Khatib, M.M., Priestley, K., Talebian, M. and Ghafuri-Ashtiani, M., 1999. The 1997 may 10 Zirkuh (Qaenat) earthquake (Mw 7.2): faulting along the Sistan suture zone of eastern Iran. Geophysical Journal Intern.ational, 136(3), 671–694.

BRGM, ORLEANS, 1983. Geological Map of Gonabad, scale 1:250000. Geological Survey of Iran.

Camp, V. E. and Griffis, R. J, 1982. Character, genesis and tectonic setting of igneous rocks in the Sistan suture zone, eastern Iran. Lithos, 15(3): 221–239.

Esperanca, S., Crisci M., de Rosa, R. and Mazzuli R.,1992. The role of the crust in the magmatic evolution of the island Lipari (Aeolian Islands, Italy. Contributions to Mineralogy and Petrology, 112(4): 450–462.

Gencalioglu Kuscu, 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.

Ghaemi, F., 2005. Geological Map of Gonabad, scale 1:100000. Geological Survey of Iran.

Gharibnavaz, A.,Ebrahimi, KH., Mazaheri, S.A., Yoosefi. A. and Mahmoudi Gharaee, M.H., 2008. The industrial mineralogy and geochemistry of REE Gonabad Ahooee& Rhokh-sefid kaolinite deposits. Fifteenth Congress of Crystallography and Mineralogy of Iran, Ferdowsi University of Mashhad, Mashhad, Iran (in Persian with English abstract).

Gill, J., 1987. Early geochemical evolution of an oceanic island arc and backarc: Fiji. The Journal of Geology, 95(5): 589-615.

Gill, R., 2010. Igneous rocks and processes. Wiley-Blackwell, New Jersey, 428 pp.

Green, M.G., Sylvester, P.J. and Buick, R., 2000. Growth and recycling of early Archaean continental crust: geochemical evidence from the Coonterunah and Warrawoona Groups, Pilbara Craton, Australia. Tectonophysics, 322(1-2): 269–288.

Harangi, S., Downes, H., Thirlwall, M. and Gmeling, K., 2007.Geochemistry, Petrogenesis and Geodynamic Relationships of Miocene Calc-alkalineVolcanic Rocks in the Western Carpathian arc, Eastern Central Europe. Journal of petrology, 48(12): 2261-2287.

Hastie, A.R., Kerr, A.C., Pearce, J.A. and Mitchell, S.F., 2007. Classification of altered volcanic island arc rocks using immobile trace elements: development of the Th-Co discrimination diagram. Journal of Petrology, 48(12): 2341- 2357.

Helvacı, C., Ersoy, E.Y., Sözbilir, H., Erkül, F., Sümer, Ö. and Uzel, B., 2009. Geochemistry and 40Ar/39Ar geochronology of Miocene volcanic rocks from the Karaburun Peninsula: Implications for amphibole-bearing lithospheric mantle source, western Anatolia. Volcanology and Geothermal Research, 185(3): 181–202.

Jung, D., Keller, J., Khorasani, R., Marcks, Chr., Baumann, A. and Horn, P., 1983. Petrology of the Tertiary magmatic activity the northern Lut area, East of Iran, Ministry of mines and metals. Geological Survey of Iran, Tehran. Report 51: 285-336.

Karimpour, M.H., Malekzadeh Shafaroudi, A., Farmer, L. and Stern, C.R., 2012.Petrogenesis of Granitoids, U-Pb zircon geochronology, Sr-Nd Petrogenesis of granitoids, U-Pb zircon geochronology, Sr-Nd isotopic characteristics, and important occurrence of Tertiary mineralization within the Lut block, eastern Iran. Journal of Economic Geology 4(1): 1-27 (in Persian with English abstract).

Karimpour, M.H., Stern, C.R., Farmer, L., Saadat, S. and Malekezadeh, A., 2011. Review of age, Rb/Sr geochemistry and petrogenesis of Jurassic to Quaternary igneous rocks in Lut Block, Eastern Iran. Geopersia, 1(1): 19–36.

Kolahdani, S., 2009.Remot sensing, techto-magmatyzm, petrology, alteration and epithermal mineralization based on electron microscopy (SEM) and fluid inclusion evidences. M.Sc. thesis. Ferdowsi university of Mashhad, Mashhad, Iran, 283 pp (in Persian with English abstract).

Kretz, R., 1983. Symbols for rock-forming minerals. American Mineralogist, 68(1-2): 277-279.

Mahdavi, A., Karimpour, M.H., Mao, J., Haidarian Shahri, M.R., Malekzadeh Shafaroudi, A. and H. Li, 2016. Zircon U–Pb geochronology, Hf isotopes and geochemistry of intrusive rocks in the Gazu copper deposit, Iran: Petrogenesis and geological implications. Ore Geology Reviews, 72(1): 818–837.

Malekzadeh Shafaroudi A., 2009. Geology, mineralization, alteration, geochemistry, Microthermometry, radioisotope and Petrogenesis of intrusive rocks copper-gold porphyry Maherabad and Khopik. Ph.D thesis. Ferdowsi University of Mashhad, Mashhad, Iran, 535 pp (in Persian with English abstract).

Malekzadeh Shafaroudi, A., 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(2): 522–544.

Marchev, P., Raicheva, R., Downes, H., Vaselli, O., Chiaradia, M. and Moritz, R., 2004. Compositional diversity of Eocene–Oligocene basaltic magmatism in the Eastern Rhodopes, SE Bulgaria: implications for genesis and tectonic setting. Tectonophysics, 393(1-4): 301-328.

Miranvari, A., 2008. Industrial mineralogy of Yasmina Kaolin deposit, Gonabad. M.Sc. thesis, Ferdowsi University of Mashhad, Mashhad, Iran, 128 pp (in Persian with English abstract).

Miri Beydokhti, R., 2004. Mineralogical and geochemical study of kaolin deposits of Baghsiah, Rokhsefid and Kabutarkuh. M.Sc thesis, University of Shiraz, Shiraz, Iran, 256 pp (in Persian with English abstract).

Miri Beydokhti,R., Karimpour, M.H., Mazaheri, S.A., Santos, J.F. and Koetzli, U., 2015. U-Pb Zircon Geochronology, Sr-Nd Geochemistry, Petrogenesis and Tectonic Setting of Mahoor Granitoid rocks (Lut Block, Eastern Iran). Journal of Asian Earth Sciences, 111: 192-205.

Moradi, M., Karimpour, M.H. and Salati, E., 2010. Geology and Petrology of intrusive rocks Eastern Najmabad. Journal of Advanced Applied Geology,1(1): 1-10.

Muir, R.J., Weaver, S.D., Bradshaw, JD, Eby, G.N. and Evans, J.A., 1995. Geochemistry of the Cretaceous Separation Point batholith, New Zealand: granitoid magmas formed by melting of mafic lithosphere. Geological Society of London, 152(4): 689–701.

Najafi, A., Karimpour, M.H., Ghaderi, M., Stern, Ch. and Farmer, L., 2014. U-Pb zircon geochronology, Rb-Sr and Sm-Nd isotope geochemistry, and petrogenesis of granitiod rocks at Kaje prospecting area, northwest Ferdows: Evidence for upper Cretaceous magmatism in Lut block. Journal of Economic Geology, 6(4): 107-135 (in Persian with English abstract).

Nakamura, N., 1974. Determination of REE, Ba, Fe, Mg, Na, and K in carbonaceous and ordinary chondrites. Geochim, Cosmochim, Acta, 38(5): 757–775.

Nakhaei, M., 2015, skarn, mineralogy, geochemical exploration magnetometry, dating, sm-nd and Rb- Sr isotopic studies of intrusive bodies in Bishe iron mineralization area, Birjand. Ph.D. thesis, Ferdowsi University of Mashhad, Mashhad, Iran, 388 pp (in Persian with English abstract).

Nakhaei, M., Mazaheri, S.A., Karimpour,M.H., Stern, C.R., Zarrinkoub, M.H., Mohammadi, S.S. and Heydarian shahri, M.R. 2015. Geochronologic, geochemical, and isotopic constraints on petrogenesis of the dioritic rocks associated with Fe skarn in the Bisheh area, Eastern Iran. Arabian Journal of Geosciences, 8(10): 8481-8495.

Pang, K.N., Chung, S.L., Zarrinkoub, M.H., Khatib, M.M., Mohammadi, S.S., Chiu, H.Y., Chu, C.H., Lee, H.Y. and Lo, C.H., 2013. Eocene–Oligocene post-collisional magmatism in the Lut–Sistan region, eastern Iran: Magma genesis and tectonic implications. Lithos, 180- 181: 234–251.

Pearce, J.A. 1983. Role of the sub-continental lithosphere in magma genesis at active continental margins. In: C.J. Hawkesworth, and M.J. Norry (Editors), Continental basalts and mantle xenoliths, Nantwich, Shiva, Cheshire, pp. 230-249.

Pearce, J.A. and Cann, J.R., 1993. Tectonic setting of basic volcanic rocks determined using trace element analyses. Earth and Planetary Science Letters, 19(2): 290–300.

Pearce, J.A. and Norry, M.J., 1979. Petrogenetic Implications of Ti, Zr, Y, and Nb Variations in Volcanic Rocks. Contributions to Mineralogy and Petrology, 69(1): 33-47.

Petford, N. and Atherton, M., 1996. Na-rich partial melts from newly underplated basaltic crust: the Cordillera Blanca Batholith, Peru. Journal of Petrology, 37(6):1491–1521.

Rollinson, H., 1993. Using geochemical data: evolution, presentation, interpretation.Longman Scientific and Technical, London, 248 pp.

Salari mendi, M., Homam, S.M. and Ebrahimi nasrabadi, Kh., 2013. Petrography and geochemistry of the volcanic rocks, Atabaki and Bagh asia area, Khorasan Razavi Province, as a host rock of kaoline deposite.Fifteenth Congress of economic geology of Iran, Ferdowsi University of Mashhad, Mashhad, Iran (in Persian with English abstract).

Samiee, S., Karimpour, M.H., Ghaderi, M., Haidarian Shahri, M.R., Kloetzli, U. and Santos, J.F., 2016. Petrogenesis of subvolcanic rocks from the Khunik prospecting area, south of Birjand, Iran: Geochemical, Sr–Nd isotopic and U–Pb zircon constraints. Journal of Asian Earth Sciences, 115: 170-182.

Schandl, E.S. and Gorton, M.P., 2000. Form continents to island arcs: A geochemical index of tectonic setting for arc-related and within-plate felsic to intermediate volcanic rocks. The Canadian Mineralogist, 38(5): 1065-1073.

Siddiqui, R.H., Asif Khan, M. and Qasim Jan, M., 2007. Geochemistry and petrogenesis of the Miocene alkaline and sub-alkaline volcanic rocks from the Chagai arc, Baluchistan, Pakistan: Implications for porphyry Cu-Mo-Au deposits. Himalayan Earth Sciences, 40: 1-23.

Smithies, R.H., Champion, D.C. and Sun, S.S., 2004. Evidence for early LREE-enriched mantle source Regions: diverse magmas from the c.3.0 Ga Mallina Basin, Pilbara Craton, NW Australia. Journal of Petrology, 45(8): 1515–1537.

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

Taylor, S.R. and McLennan, S.M., 1985. The continental crust, its composition and evolution, an examination of the geochemical record preserved in sedimentary rocks. Blackwell, Oxford, 312 pp.

Tepper, J.H., Nelson, B.K., Bergantz, G.W. and Irving, A.J., 1993. Petrology of the Chilliwack batholith, North Cascades, Washington: generation of calc-alkaline granitoids by melting of mafic lower crust with variable water fugacity. Contributions to Mineralogy and Petrology, 113(3): 333-351.

Tirrul, R., Bell, I.R., Griffis, R.J. and Camp, V.E., 1983. The Sistan suture zone of eastern Iran. Geological Society of America Bulletin, 94(1): 134–150.

Verdel, C., Wernicke, B.P., Ramezani, J., Hassanzadeh, J., Renne, P.R. and Spell, T.L., 2007. Geology and thermochronology of Tertiary Cordilleran-style metamorphic core complexes in the Saghand region of central Iran. Geological Society of America Bulletin, 119(8): 961-977.

Wilson, M., 1989.igneous petrogenesis. Unwin Hyman, London, 466 pp.

Winchester, J.A. and Floyd, P.A., 1977. Geochemical discrimination of different magma series and their differentiation products using immobile elements. Chemical Geology, 20(4): 325-343.

Zirjanizadeh, S., Karimpour, M.H. and Ebrahimi, Kh., 2014.geological, mineralogical and geochemical studies of Kalateno kaolin deposits (northwest Gonabad). Crystallography and Mineralogy of Iran, 22 (1): 125-138 (in Persian with English abstract).