Petrology, geochronology, geochemistry and petrogenesis of Bajestan granitoids, North of Ferdows, Khorasan Razvi Province

زمین شناسی اقتصادی

Article 14, Volume 8, Issue 2 - Serial Number 15, February 2017, Pages 525-552   

Document Type: Research Article

DOI: 10.22067/econg.v8i2.57139

Authors

Reyhaneh Ahmadirouhani¹; Mohammad Hassan Karimpour^{* 1}; Behnam Rahimi¹; Azadeh Malekzadeh Shafaroudi¹; Urs Klotzli²; Jose Francisco Santos³

¹Ferdowsi University of Mashhad

²Vienna

³Aveiro

Abstract

Introduction
The investigated area is situated in the south west of the Khorasan Razavi Province along the North West of the Lut Block. Different types of metal ore bodies along with non-metal deposits have already been documented in the Lut Block (Karimpour et al., 2008). Most of the study area is covered with granitoid rocks. Metamorphic rocks with unknown age are present in the north of the area. Skarns are observed in contact with fault zones and intrusive bodies. Eocene volcanic rocks with andesite and andesibasalt composition are located in the east and north east of the area (Ahmadirouhani et al., 2015). The study area that is a part of the Lut Block has a high potentials for Cu, Fe, Au, and Barite mineralization along the observed alteration zones. In the present study, the petrography, petrogenesis, Sr–Nd isotopes, and U–Pb zircon age of acidic granitoids in the east of Bajestan were investigated.

Materials and methods
In the current study, 400 rock samples were collected from the field and 170 thin sections were prepared for petrography studies. Thirty samples of volcanic rocks, intrusions, and dykes were analyzed using XRF at the Geological Survey of Iran. Twenty-five samples were selected for the elemental analysis using ICP-MS by the Acme Lab Company (Canada), 16 samples of them were related to acidic intrusive bodies and dykes. In addition, zircon crystals from four samples of the granitoids bodies were collected for U–Pb dating. Approximately 50 zircon grains (i.e. euhedral, clear, uncracked crystals with no visible heritage cores and no inclusions) were hand-picked from each sample. Through cathodoluminescence imaging, the internal structure and the origin of zircon grains were examined at the Geological Survey of Vienna, Austria. Moreover, zircons were dated using the (LA)-ICP-MS method at the Laboratory of Geochronology, the University of Vienna, Austria using the methodology outlined in Klötzli et al., (2009). Sr and Nd isotopic compositions were also determined for the same samples (i.e. U-Pb samples) using the whole-rock method. The samples were analyzed in the Laboratório de Geologia Isotópica da Universidade de Aveiro, Portugal.

Results
Granitoids in the study area have mostly monzogranite (biotite monzogranite, hornblende biotite monzogranite and pyroxene hornblende biotite monzogranite), granite, and syenogranite composition. Granular, micro-granular, and porphyritic textures are common textures in these rocks. Common mafic minerals in these rocks include biotite, hornblende and pyroxene. Based on mineralogy, low values of magnetic susceptibility, high aluminum saturation index, and high initial 87Sr/86Sr ratios (> 0.710) of the study of granitoid rocks belong to the ilmenite-series of the reduced S-type granitoids. These magmas originated from the upper continental crust at a syncollosion zone. Furthermore, the rocks normalizing spider diagrams showed characteristics of a crustal environment. The age of the granitoids based on zircon U–Pb age dating was determined, including granite porphyry (79±1 Ma), syenogranite (76±1 Ma), biotite monzogranite (76±1 Ma), all of which belong to the Upper Cretaceous (Campanian), except pyroxene hornblende biotite monzogranite with 30.7±1 Ma, Oligocene age (Rupelian) has a different age. The ranges of their initial 87Sr/86Sr and 143Nd/144Nd ratios for Upper Cretaceous granitoids are 0.710897–0.717908 and 0.511995–0.512186, respectively while they are 0.713292 and 0.512186 for Oligocene intrusion. The initial єNd isotope values for the syenogranite, biotite monzogranite, and granite porphyry are -10.65, -7.38 and -9.51, respectively. The initial єNd isotope value for pyroxene hornblende biotite monzogranite is -8.06. The values of the igneous rocks could be considered as representative of continental crust derived from magma, and melt derived from psammite rocks is considered to have been the source of the granitoids.

Discussion
Based on the U-Pb dating results, there are two magmatism phases (Upper Cretaceous and Oligocene) in the area which have not reported in the north of Lut Block yet. During the Upper Cretaceous, three localities of granitoids are reported, excluding Bajestan: Bazman (initial 87Sr/86Sr =0.7056) is located in the southern part of the Lut Block, Gazu (initial 87Sr/86Sr =0.7045) is located near the Nayband fault in the Tabas Block and Kaje is located in Ferdows (initial 87Sr/86Sr =0.7061-0.7080). All of these granitoids were formed due to the subduction zone and their magma (I type) originated from mantle. However, granitoids in Bajestan with the initial 87Sr/86Sr =0.711-0.718 were formed during the continental collision while their magma was originated from the continental crust. In addition, the Middle Jurassic granitoids in the Lut Block (Shah Kuh, KlatehAhani and SurkhKuh) with the origin of continental crustal magma have an initial 87Sr/86Sr = 0.7068-0.7081. That is, the continental crust from which Bajestan granitoid magma is originated, is different from the other parts of the Lut Block due to very high (87Sr/86Sr). This indicates that Bajestan perhaps joined the Lut Block after the Upper Cretaceous collision.
In addition to Bajestan, the Oligocene granitoids in the Lut block are reported in the Chah-Shaljami, Dehsalm, Mahoor and Khunik areas. Except Bajestan, all of these granitoids were formed in the subduction zone and their magma is I type. Mineralization in Chah-shaljami, Dehsalm, and Mahoor is related to the porphyric system, whereas no mineralization in Khunik and Bajestan Granitoids has been reported yet.

References
Ahmadirouhani, R., Karimpour, M.H., Rahimi, B. and Malekzadeh Shafaroudi, A., 2015. Enhance of alteration zones and lineation in the east of Bajestan using SPOT, ASTER, ETM+ and Geophysics data. Scientific Quaternary Journal Geosciences, 24: 253-262.
Karimpour, M.H., Malekzadeh-Shafaroudi. A., Stern. C.R. and Hidarian, M.R., 2008. Using ETM+ and airborne geophysics data to locating porphyry copper and epithermal gold deposits in Eastern Iran. Journal of Applied Science, 8: 4004–4016.
Klötzli, U., Klötzli, E., Günes, Z. and Kosler, J., 2009. Accuracy of laser ablation U–Pb zircon dating: results from test using five different reference zircons. Geostandards and Geoanalytical Research, 33: 5–15.

Keywords

U-Pb dating; Rb-Sr and Sm-Nd isotopes; Bajestan; the Lut Block; Iran

References

Aghanabati, S.A., 2013. Geology of Iran and Neighbouring countries. Geological Survey of Iran, Rahi press, Tehran 710 pp.

Ahmadirouhani, R., Karimpour, M.H., Rahimi, B. and Malekzadeh Shafaroudi, A., 2015. Enhance of alteration zones and lineation in the east of Bajestan using SPOT, ASTER, ETM+ and Geophysics data. Scientific Quaternary Journal Geosciences, 24(94): 253-262.

Arjmandzadeh, R., 2011. Mineralization, geochemistry, geochronology, and determination of tectonomagmatic setting of intrusive rocks in Dehsalm and Chahshaljami prospectareas, Lut block, east of Iran. PhD. Thesis, Ferdowsi University of Mashhad, Mashhad, Iran, 215 pp. (in Persian)

Arjmandzadeh, R. and Santos, J.F., 2014. 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.

Ashoori, A.R., Karimpour, M.H. and Saadat, S., 2005. Geological map of Bajestan. scale:1:100000. Geological Survey of Iran.

Berberian, F., 1981. Petrogenesis of Iranian plutons: a study of the Natanz and Bazman complex. Unpublished Ph.D. Thesis, University of Cambridge, Cambridge, England, 300 pp.

Boynton, W.V., 1984. Geochemistry of the rare earth elements: meteorite studies. In: P. Henderson (Editor), Rare earth element geochemistry.Elsevier, Amsterdam, pp. 63-114.

Chappell, B.W. and White, A.J.R., 1974. Two contrasting granite types, Pac. Geology, 8:173-174.

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 Edinburg, Earth Science, 83(1-2): 1-26.

Chappell, B.W. and White, A.J.R., 2001. Two contrasting granite type: 25 years later. Australian Journal of Earth Science, 48(4): 489–499.

Eftekharnezhad, J., Valeh, N., Ruttner. A., Nabavi, M.H., Hajian, J., Alavi, M. and Haghipour, A., 1977. Geological map of Ferdows. scale: 1:250.000. Geological Survey of Iran.

Esmaeily, D., Ne´de´lecb, A., Valizadeha, M.V., Moorec, F. and Cotten J.2005. Petrology of the Jurassic Shah-Kuh granite (eastern Iran), with reference to tin mineralization. Journal of Asian Earth Sciences, 25(6) : 961–980.

Ghurchi, M., Ashoori, A.R. and Saadat, S., 2009. Petrology, Alteration and mineralization of Taher-abad and Bajestan intrusive bodies. Journal of Economic geology, 1(1): 83–101.

Gill, J.B., 1981. Orogenic Andesites and Plate Tectonics (Minerals, Rocks and Mountains). Springer, Germany, 392 pp.

Harris, C., 1983, The petrology of lavas andassociated plutonic inclusions of AscensionIsland. Journal of Petrology, 24(4): 424-470.

Ishihara, S., 1977. The magnetite-series and ilmenite-series granitic rocks. Mining Geology, 27: 293–305.

Ishihara, S., 1981. The granitoid series and mineralization. Economic Geology, 75: 458 – 484.

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, 519 pp.

Karimpour, M.H., Farmer, G.L. and Stern, C.R., 2009a. Rb–Sr and Sm–Nd Isotopic compositions, U-Pb Age and Petrogenesis of Khajeh Mourad Paleo-Tethys Leucogranite, Mashhad, Iran. Quarterly Journal of Earth Sciences, 20(3): 171–182.

Karimpour, M.H., Malekzadeh Shafaroudi, A., Mazaheri, A. and Heydarian shahri, M.R., 2007. Magmatism and Cu, Au, Sn and W mineralization types in the Lut block. The 15th Symposium of the Society of Crystallography & Mineralogy of Iran, Ferdowsi University of Mashhad, Mashhad, Iran.

Karimpour, M.H., Malekzadeh Shafaroudi, A., Stern, C.R. and Hidarian, M.R., 2008. Using ETM+ and airborne geophysics data to locating porphyry copper and epithermal gold deposits in Eastern Iran. Journal of Applied Science, 8: 4004-4016.

Karimpour, M.H., Stern, C.R., Farmer, L., Saadat, S. and Malekzadeh Shafaroodi, 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.

Karimpour, M.H., Stern, C.R., Malekzadeh‌ Shafaroudi, A., Heidarian, M.R. and Mazaheri, A., 2009b. Petrochemistry of the reduced, ilmenite-series granitoid intrusion related to the Hired Au-Sn prospect, Eastern Iran. Journal of Applied Sciences, 9(2): 226–236.

Katongo, C., Koller, F., Klötzli, U., Koeberl, Ch., Tembo, F. and Waele, B., 2004. Petrography, geochemistry, and geochronology of granitoid rocks in the Neoprotrozoic- Paleozoic Lufilian- Zambezi belt, Zambia: Implications for tectonic setting and regional correlation. Journal of African Earth Sciences, 40(5): 219–244.

Klötzli, U., Klötzli, E., Günes, Z. and Kosler, J., 2009. Accuracy of laser ablation U–Pb zircon dating: results from a test usingfive different reference zircons. Geostandards andGeoanalytical Research, 33(1): 5–15.

Ludwig, K.R., 2008. User's manual for Isoplot/Ex version 3.70. A geochronological tool kit for Microsoft Excel. Berkeley Geochronology Center Special, Publication, No. 4.

Mahdavi, A., Karimpour, M.H., Mao, J., Haidarian Shahri, M.R. and Malekzadeh Shafaroudi, A., 2016. Hongying Li, 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, isotope studies and determining the mineralization source of Khoopic and Maherabad exploration areas. Ph.D. thesis. Ferdowsi university of Mashhad, Mashhad, Iran, 606 pp.

McCulloch, M.T. and Bennett, V.C., 1994. Progressive growth of the Earth’s continentalcrust and depleted mantle: Geochemical constraints. Geochimica et Cosmochimica Acta, 58(21): 4717-4738.

McCulloch, M.T., Kyser, T.K., Woodhead, J.D. and Kinsley, L., 1994. Pb–Sr–Nd–O isotopic constraints on the origin of rhyolites from the Taupo volcanic zone of New Zealand: evidence for assimilation followed by fractionation of basalt. Contributions to Mineralogy and Petrology, 115:(3) 303–312. Middlemost, E.A.K., 1985. Magmas and magmatic rocks. Longman, London & New York , 266 pp.

Miri Beydokhti, R., Karimpour, M.H., Mazaheri, A., Santos, J. and Klötzli, 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., Farmer, G.L. and Stern, C.R., 2011. Isotope geochemistry of Rb-Sr & Sm- Nd, U- Pb geochrology and petrogenesis of Najmabad granodirite batholith, Gonabad. Journal of Economic geology, 3(2): 127–143.

Najafi, A., Karimpour, M.H., Ghaderi, M., Stern, C.R. and Farmer, G.L., 2014. U-Pb dating of zircon, Isotope geochemistry of Rb-Sr & Sm- Nd and petrogenesis of granitoid intusives in Kaje prospect, north west of Ferdows, evidence on Late Cretaceous magmatism in the Lut block. Journal of economic geology, 6(1):107–135.

Pearce, J.A., 1983. Role of 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, UK, Shiva, pp. 230–249.

Pearce, J.A., Harris, N.B.W. and Tindle, A.G., 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, 25(4): 956–983.

Pearce, J.A. and Parkinson, I.J., 1993. Trace element models for mantle melting: application to volcanic arc petrogenesis. In: H.M, Prichard, T. Albaster, N.B.W. Harris and C.R. Neary (Editors), Magmatic Processes in Plate Tectonics. Geological Society , London, pp. 373– 403.

Peccerillo, A. and 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.

Pourlatifi. A., 2002. Geological map of Ferdows. scale: 1:100000, Geological survey of Iran.

Reagan, M.K. and Gill, J.B., 1989. Coexisting calcalkaline and high niobium basalts from Turrialba volcano, Costa Rica: implication for residual titanates in arc magma source. Journal of Geophysical Research, 94(B4): 4619 – 4633.

Richards, J.P., Spell, T., Rameh, E., Razique, A. and Fletcher, T., 2012. High Sr/Y reflect arc maturity, high magmatic water content, and porphyry Cu ± Mo ± Au potential: examples from the Tethyan arcs of central and eastern Iran western Pakistan. Economic Geology, 107(2): 295–332.

Rollinson, H.R., 1993. Using Geochemical Data: Evaluation, Presentation, and Interpretation. Longman Science and Technical,Routledge, 352 pp.

Rudnick, R.L., 1995. Making continental crust. Nature, 378(6557): 571-578.

Samiee, S., Karimpour, M.H., Ghaderi, M., Heidarian Shahri, M.H., Klöetzli, U. and -Santos, J., 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(15): 170–182.

Shand, S.J., 1947. Eruptive rocks: Their genesis, composition, classification and their relation to ore-deposits. Hafner Publishing Company, New York, 488 pp.

Slama, J., Kosler, J., Schaltegger, U., Tubrett, M. and Gutjahr, M., 2006. New natural zircon standard for laser ablation ICP-MS U-Pb geochronology. Winter Conference on Plasma Spectrochemistry, Tucson, Arizona,US.

Sun, S.S. and McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. Geology Society Special Publication, 42(1): 313–345.

Sylvester, P.J., 1998. Post-collisional strongly peraluminous granites. Lithos, 45(1-4): 29-44.

Tarkian, M., Lotfi, M. and Baumann, A., 1983. Tectonic, magmatism and the formation of mineral deposits in the central Lut, east Iran, Ministry of Mines and Metals. Geological Survey of Iran, geodynamic project (geotraverse) in Iran, 51: 357–383.

Taylor, S.R. and McLennan, S.M., 1985. The continental crust: its composition and evolution. Blackwell Scientific Publication, Carlton, 312 pp.

Thompson, A.B., 1982. Dehydration melting of pelitic rocks and the generation of H2O-undersaturated granitic liquids. American Journal of Science, 282(10): 1567–1595.

Vervoort, J.D., Patchett, P.J., Blichert Toft, J., Albarede, F., 1999. Relationship between Lu-Hf and Sm-Nd isotopic systems in the global sedimentary system. Earth and Planetary Science Letters, 168(1-2):79-99.

Watt, G.R. and Harley, S.L., 1993. Accessory phase controls on the geochemistry of crustal melts and restites produced during waterundersaturated partial melting. Contributions to Mineralogy and Petrology, 114(4): 550–566.

Whalen, J.B., Currie, K.L. and Chappell, B.W., 1987. A-type granites: geochemical characteristics, discrimination and petrogenesis. Contributions to Mineralogy and Petrology, 95(4): 407–419.

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

Wilson, M., 1989. Igneous Petrogenesis: A Global Tectonic Approach. Dordrecht Springer, Netherland, 466 pp.