Geology, petrology, geochemistry and geochronology of Tarik Darreh plutonic rocks, northeastern Iran

Document Type : Research Article

Authors

• Jamal Ghavi ¹
• Mohammad Hassan Karimpour ¹
• Seyed Ahmad Mazaheri ¹
• Majid Ghaderi ²
• Behnam Rahimi ¹

¹ Ferdowsi University of Mashhad

² Tarbiat Modares University

10.22067/econg.v12i2.69021

Abstract

Introduction
The investigated area in northeastern Iran that is known as the Tarik Darreh arsenopyrite-Au-W prospecting target is situated in the Kopeh Dagh zone (Fig. 1). Most of the study area is covered with black slate rocks which most authors have referred to as Upper Triassic with Norian age (e.g., Behroozi et al., 1993). Plutonic rocks with gabbro, diorite, and quartz diorite and monzodiorite composition were introduced in the slate rocks. The previous studies in the Tarik Darreh are the preliminary report of arsenopyrite with Au-W quartz lode mineralization carried out by Taghizadeh (1965). Since then, the Geological Survey of Iran (e.g., Alavi Naini and Mossavi-Khorzughi, 2006) a few geologic companies and the universities (Shafi Niya, 2002) and Ghavi et al. (2013) have been studying in the area. In the present study, we provide more information, complete with new information about the geology of the Tarik Darreh area.
 
Materials and methods
Expansive field geology surveying to draw a geology map in 1:8000 scale and sampling from plutonic rocks was performed and two main fault system were distinguished in Tarik Darreh (Figs. 2 and 3). Thin section microscopic studies were carried out following field investigations. Magnetic susceptibility was measured with a portable Model KT-10 and GMS-2 Fugro instrument (precision of 0.0001 SI units).
Sixteen samples of intrusive bodies and dykes were analyzed for major and trace elements using 4E-Reserch package (INAA, FUS ICP-OMS, ICP-MS) at the Acme Lab (Canada). Gabbroic units were selected for U-Pb geochronological study. In the heavy liquid process, zircon crystals were separated, hand-picked under microscope. Zircon grains for Th-U-Pb dating were examined by an Agilent 7700 quadrupole ICPMS at the University of Tasmania (Australia).
 
Discussion and Results
Plutonic rocks in the Tarik Darreh area are in the form of bodies and dykes. The plutonic bodies are mostly gabbro, gabbro diorite, diorite (hornblende pyroxene diorite, biotite hornblende diorite and hornblende biotite diorite), biotite hornblende monzodiorite, quartz diorite, and quartz monzonite in composition. However, it is diorite with granular textures as a common rock (Figs. 4 and 6). Other rocks as dyke have more hornblende diorite composition with porphyritic textures. Common mafic minerals in the plutonic rocks in the Tarik Darreh include pyroxene, hornblende and biotite. The alteration assemblages of uralite, chlorite, calcite and sericite are very common gabbroic-diorite rocks (Fig. 5). The plutonic rocks have SiO2 with values in the range of 46 to 56% (Table 1). Therefore, these rocks are intermediate in composition.  Most of these rocks also have high K-calc-alkaline composition with metaluminous characteristic (Fig. 7).
Enrichment in LREE relative to HREE, low La/By ratio, enrichment in LILE and negative anomaly of Eu, Ti, Zr, Y and Ba are shared in all of the studied plutonic rocks and dykes (Figs. 8 and 9). All the plutonic rocks have low values of magnetic susceptibility (less than 3×10-3 SI). Two main systems of fault have affected the area (Fig. 10). Plutonic rocks from the Tarik Darreh area are placed within the volcanic arc to within plate’s environment in tectonic setting discrimination diagrams (Fig. 11).
Zircon U-Pb dating results on the gabbroic rocks are shown in Table 2. Zircon grains through cathodoluminescence imaging show euhedral, clear crystals with no visible heritage cores. However, some of them have inclusions. Zircon U-Pb dating indicates that the gabbroic rocks formed at 215.5±0.9 Ma (late Triassic) (Fig. 12). Thus, it is obvious that the country rock (called Miankuhi Formation), must be older than the late Triassic plutonic rocks rather than Norian age as previously thought.
The variation of major elements with SiO2 in the plutonic rocks from Tarik Darreh (Fig. 13) indicates that the primary magma of these plutonic rocks underwent fractional crystallization from gabbro to quartz monzodiorite. Geochemical characteristics such as low ratios of (La/Yb)N (<13), high contents of MgO (7%), high Mg# (57) and high Sr (on average 572 ppm) indicate that the magma of the studied rocks have probably originated from partial melting of garnet-free source from mantle or low continental crust. However, the presence of slate as country rocks suggest possible assimilation of country rocks that indicate processes such as assimilation were more likely to be responsible for the evolution of plutonic rocks in the Tarik Darreh area.
 
Acknowledgements
The authors wish to thank Prof. Yuanming Pan (University of Saskatchewan) for supporting this study and Eng. Amin Haghdoost for his help during the field geology work.
 
References
Alavi Naini, M. and Mossavi-Khorzughi, E., 2006. Geological Map of Torbat-e-Jam, scale1:100,000. Geological Survey of Iran.
Behroozi, A., Eftekharnezhad, J. and Alavi Naini, M., 1993. Geological Map of Torbat-e-Jam, scale 1:250,000. Geological Survey of Iran, Tehran.
Ghavi, J., Karimpour, M.‌H., Mazaheri, S.‌A., Ghaderi, M. and Rahimi, B., 2013. Identifying secondary dispersion halos and geochemical element distribution in soils on the Tarik Darreh Au-W prospect area, north of Torbat-e-Jam, NE Iran. Iranian Journal of Crystallography and Mineralogy, 21(1): 107–120. (in Persian)
Shafi Niya, H., 2002. Geochemical and geological studies of Tarik Darreh gold prospect, M.Sc. Thesis, Shahid Beheshti University, Tehran, Iran, 157 pp. (in Persian)
Taghizadeh, N., 1965. Prospecting at Tarik Dareh-Cheshmegool area. Geological Survey of Iran, Tehran, Report 1, 8 pp.

Keywords

• Th-U-Pb geochronology
• Gabbro
• diorite
• ilmenite series
• Upper Triassic
• Tarik Darreh
• NE Iran

20.1001.1.20087306.1399.12.2.4.3

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References

Aghanabati, A., 2004. Geology of Iran. Geological Survey of Iran, Tehran, 606 pp. (in Persian)

Alavi Naini, M. and Mossavi-Khorzughi, E., 2006. Geological Map of Torbat-e-Jam, scale1:100,000. Geological Survey of Iran.

Almasi, A., Karimpour, M.H., Hattori, K., Santos, J.F., Ebrahimi Nasrabadi, Kh. and Rahimi, B., 2016. Au-bearing magnetite mineralizaion in Kashmar (alteration, mineralization, geochemistry, geochemistry and fluid inclusions); and Tectono-magmatism of northeast of Iran. Journal of Economic Geology, 8(2): 569–592. (in Persian with English abstract)

Ahmadirouhani, R., Karimpour, M.H., Rahimi, B., Malekzadeh Shafaroudi, A., KlÖtzli, U. and Santos, J.F., 2016. Petrology, geochronology, geochemistry and petrogenesis of Bajestan granitoids, North of Ferdows, Khorasan Razvi Province. Journal of Economic Geology, 8(2): 525–552. (in Persian with English abstract)

Behroozi, A., Eftekharnezhad, J. and Alavi Naini, M., 1993. Geological Map of Torbat-e-Jam, scale 1:250,000. Geological Survey of Iran, Tehran.

Boynton, W.V., 1984. Geochemistry of Rare Earth Elements: Meteorite Studies. In: P. Henderson (Editor), Rare Earth Element Geochemistry. Elsevier, New York, pp. 63–114.

De La Roche, H., Leterrier, J., Grandclaude, P. and Marchal, M., 1980. A classification of volcanic and plutonic rocks using R1R2-diagram and major element analyses: its relationships with current nomenclature. Chemical Geology, 29(1–4): 183–210.

Ghavi, J., Karimpour, M.H., Mazaheri, S.A., Ghaderi, M. and Rahimi, B., 2013. Identifying secondary dispersion halos and geochemical element distribution in soils on the Tarik Darreh Au-W prospect area, north of Torbat-e-Jam, NE Iran. Iranian Journal of Crystallography and Mineralogy, 21(1): 107–120. (in Persian)

Halpin, J.A., Jensen, T., McGoldrick, P., Meffre, S., Berry, R.F., Everard, J.L., Calver, C.R., Thompson, J., Goemann, K. and Whittaker, J.M., 2014. Authigenic monazite and detrital zircon dating from the Proterozoic Rocky Cape Group, Tasmania: Links to the Bel-Purcell Supergroup, North America. Precambrian Research, 250(1): 50–67.

Ishihara, S., 2004. The redox state of granitoids relative to tectonic setting and earth history; the magnetite-ilmenite series 30 years later. In: S. Ishihara, W.E. Stephens, L. Harley, M. Arima, and T. Nakajima (Editors), Fifth Hutton Symposium: The Origin of Granites and Related Rocks. Geological Society of America, Toyohashi, Japan, pp. 23–33.

Ishihara, S., Matsuhisa, Y., Sasaki, A. and Terashima, Sh., 1985. Wall rock assimilation by magnetite-series granitoid at the Miyako pluton, Kitakami, Northeastern Japan. The Journal of the Geological Society of Japan, 91(10): 679–690.

Karimpour, M.H., Stern, C.R. and Farmer, L., 2010. Zircon U–Pb geochronology, Sr–Nd isotope analyses, and petrogenetic study of Dehnow diorite and Kuhsangi granodiorite (Paleo-tethys), NE Iran. Journal of Asian Earth Sciences, 37(4):384–393.

Middlemost, E.A.K., 1985. Magmas and Magmatic Rocks. An Introduction to Igneous Petrology. Longman Group Ltd., London, 266 pp.

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.

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.

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(1): 891–931.

Shafi Niya, H., 2002. Geochemical and geological studies of Tarik Darreh gold prospect, M.Sc. Thesis, Shahid Beheshti University, Tehran, Iran, 157 pp. (in Persian)

Shand, S.J., 1943. Eruptive Rocks. Their Genesis Composition. Classification, and Their Relation to Ore-Deposits. John Wiley & Sons, New York, 488 pp.

Streckeisen, A., 1974. Classification and nomenclature of plutonic rocks. Geologische Rundschau, 63(1): 773–786.

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, London, pp. 313–345.

Taghizadeh, N., 1965. Prospecting at Tarik Dareh-Cheshmegool area. Geological Survey of Iran, Tehran, Report 1, 8 pp.

Takagi, T., 2004. Origin of magnetite and ilmenite series granitic rocks in the Japan Arc. American Journal of Science, 304(2): 169–202.

Terekhov, E.N. and Shcherbakova, T.F., 2006. Genesis of positive Eu anomalies in acid rocks from the Eastern Baltic Shield. Geochemistry International, 44(5): 439–45.

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

Wilson, B.M., 1989. Igneous Petrogenesis: A Global Tectonic Approach. Unwin Hyman, London, 466 pp.

Wones, D.R., 1981. Mafic silicates as indicators of intensive variables in granitic magmas. Mining Geology, 31(4):191–212.

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(1): 11–30.