Geology, mineralization and geochemistry of the Aqkand Cu occurrence (north of Zanjan, Tarom-Hashtjin zone)

زمین شناسی اقتصادی

Article 13, Volume 8, Issue 2 - Serial Number 15, February 2017, Pages 507-524   

Document Type: Research Article

DOI: 10.22067/econg.v8i2.49150

Authors

Maryam Feyzi; Mohammad Ebrahimi; Hossein Kouhestani^* ; Mir Ali Asghar Mokhtari

Zanjan

Abstract

Introduction
The Aqkand Cu occurrence, 48 km north of Zanjan, is located in the Tarom subzone of the Western Alborz-Azerbaijan structural zone. Apart from small scale geological maps of the area, i.e., 1:250,000 geological maps of Bandar-e-Anzali (Davies, 1977) and 1:100,000 geological maps of Hashtjin (Faridi and Anvari, 2000) and a number of unpublished perlite exploration reports, prior to this research no work has been done on Cu mineralization at Aqkand. The present paper provides an overview of the geological framework, the mineralization characteristics, and the results of geochemistry study of the Aqkand Cu occurrence with an application to the ore genesis. Identification of these characteristics can be used as a model for exploration of this type of copper mineralization in the Tarom area and elsewhere.

Materials and methods
Detailed field work has been carried out at different scales in the Aqkand area. About 35 polished thin and thin sections from host rocks and mineralized and altered zones were studied by conventional petrographic and mineralogic methods at the University of Zanjan. In addition, a total of 6 samples from ore zones at the Aqkand occurrence were analyzed by ICP-MS for trace elements and REE compositions at Kimia Pazhuh Alborz Co., Isfahan, Iran.

Results and Discussion
The oldest units exposed in the Aqkand area are Eocene volcanic rocks which are overlain unconformably by Oligocene acidic rocks. The Eocene units consist of lithic and vitric tuff with intercalations of andesitic basalt lavas (equal to Karaj Formation, Hirayama et al., 1966). The andesitic basalt lavas show porphyritic texture consisting of plagioclase and altered ferromagnesian minerals set in a fine-grained groundmass. The Oligocene acidic rocks consist of rhyolite-rhyodacite, perlite, pitchstone and ignimbrite. These rocks are exposed as domes and lava flows. The rhyolite-rhyodacite lavas usually show onion-skin weathering and locally display flow bands. Rapid cooling of rhyolitic-rhyodacitic lavas has resulted in the formation of volcanic glasses (obsidian). Hydration of these volcanic glasses by hydrothermal fluids caused perlite formation which is located in the lower parts of the rhyolitic-rhyodacitic domes.
Copper mineralization at Aqkand occurs as Cu-bearing quartz-fluorite veins in Eocene andesitic basalt lavas. The main ore vein reaches up to 50 m in length and average of 2 m in width. It has NW-trend and mostly dips NE. Six stages of mineralization can be distinguished at the Aqkand Cu occurrence. Stage-1 is characterized by

Keywords

Geology; mineralization; Geochemistry; Aqkand; Zanjan; Tarom-Hashtjin

References

Alavi, M., 1991. Sedimentary and structural characteristics of the Paleo-Tethys remnant in northeastern Iran. Geological Society of America Bulletin, 103(8): 983–992.

Alderton, D.H.M., Pearce, J.A. and Potts, P.J., 1980. Rare earth element mobility during granite alteration: evidence from south-east England. Earth and Planetary Science Letters, 49(1): 149–165.

Davies, R.G., 1977. Geological map of Bandar-e-Anzali, scale 1:250,000. Geological Survey of Iran.

Dokuz, A., Tanyolu, E. and Genc, S., 2005. A mantle and a lower crust derived bimodal suite in the Yusufeli Artvin area, NE Turkey: Trace element and REE evidence for subduction–related rift origin of early Jurasic Demirkent intrusive complex. International Journal of Earth Sciences, 95(3): 370–394.

Dong, G., Morrison, G. and Jaireth, S., 1995. Quartz textures in epithermal veins, Queensland; classification, origin and implication. Economic Geology, 90(6): 1841–1856.

Ebrahimi, M., Kouhestani, H. and Shahidi, E., 2015. Investigation on type and origin of iron mineralization at Mesgar occurrence, south of Zanjan, using petrological, mineralogical and geochemical data. Journal of Economic Geology, 7(1): 111–127 (in Persian with English abstract).

Faridi, M. and Anvari, A., 2000. Geological map of Hashtjin, scale 1:100,000. Geological Survey of Iran.

Ghorbani, M., 2007. Economic geology, mineral deposit and natural resources of Iran. Arian Zamin, Tehran, 492 pp (in Persian).

Hatami, A., Ebrahimi, M. and Yasami, N., 2011. Study of mineralization at Mari Cu deposit, north of Zanjan. 2nd Symposium of Iranian Society of Economic Geology, University of Lorestan, Khorramabad, Iran (in Persian with English abstract).

Hirayama, K., Samimi, M., Zahedi, M. and Hushmand-Zadeh, A., 1966. Geology of the Tarom District, Western Part (Zanjan area north-west Iran), Geological Survey of Iran, Tehran, Report 8, 31 pp.

Ineson, P.R., 1989. Introduction to practical ore microscopy. Longman Scientific and Technical, London, 181 pp.

Khakzad, A. and Hajalilou, B., 1999. Investigation on Pb, Zn and Cu mineralization in northwest of Zanjan and east of Mianeh and their relation to pervasive hydrothermal alteration. 3rd Symposium of Geological Society of Iran, University of Shiraz, Shiraz, Iran (in Persian with English abstract).

Khanmohammadi, N., Khakzad, A. and Izadyar, J., 2009. Mineralography, structural and textural studies and genesis of Zaker iron-apatite deposit (northeast of Zanjan). Geological Survey of Iran, Scientific Quarterly Journal of Geosciences, 76 (1): 119–126 (in Persian with English abstract).

Kouhestani, H., 2011. Geology, Alteration, Isotope Geochemistry and Origin of Chah Zard Ag–Au Deposit Southwest of Yazd. Ph.D. Thesis, Tarbiat Modares University, Tehran, Iran, 285 pp (in Persian with English abstract).

Kouhestani, H., Ghaderi, M., Zaw, K., Meffre, S. and Emami, M.H., 2012. Geological setting and timing of the Chah Zard breccia-hosted epithermal gold-silver deposit in the Tethyan belt of Iran. Mineralium Deposita, 47(4): 425–440.

Kouhestani, H. and Mokhtari, M.A.A., 2013. Geological and mineralization characteristics of Aliabad Cu occurrence, Tarom area, east of Zanjan. 17th Symposium of Geological Society of Iran and the 1st International Congress on Zagros Orogen, Shahid Beheshti University, Tehran, Iran (in Persian).

Mehrabi, B., Choghaneh, N. and Tale Fazel, E., 2009. Petrology, mineralogy and alteration studies of anomaly no. 4 of Gulloje polymetal deposit (northwest of Zanjan). 1st Symposium of Iranian society of Economic Geology, Ferdowsi University of Mashhad, Mashhad, Iran (in Persian with English abstract).

Mehrabi, B., Tale Fazel, E., Ghasemi Siani, M. and Eghbali, M.A., 2010. Investigation on mineralization and genetic model of Gulloje Cu-Au vein deposit (north of Zanjan), using mineralogical, geochemical and fluid inclusion data. Journal of Sciences, 35(4): 185–199 (in Persian with English abstract).

Moayyed, M. and Moazzen, M., 2001. Iron mineralization associated with Oligocene epizonal plutonic bodies at Zaker-Sorkhe Dizaj area (southwest of Tarom). 5th Symposium of Geological Society of Iran, University of Tehran, Tehran, Iran (in Persian).

Nabatian, G. and Ghaderi, M., 2014. Mineralogy and geochemistry of rare earth elements at iron oxide-apatite deposits of Zanjan area. Geological Survey of Iran, Scientific Quarterly Journal of Geosciences, 93 (3): 157–170 (in Persian with English abstract).

Nabatian, G., Ghaderi, M., Rashidnejad Omran, N., and Daliran, F., 2007. Iron-apatite mineralization at Sorkhe Dizaj, Aliabad and Morvarieh deposits, southeast of Zanjan. 15th Symposium of Crystallography and Mineralogy of Iran, Ferdowsi University of Mashhad, Mashhad, Iran (in Persian with English abstract).

Nabatian, G., Ghaderi, M., Rashidnejad Omran, N. and Daliran, F., 2009. Geochemistry and origin of apatite-bearing iron oxide deposit of Sorkhe Dizaj, SE Zanjan. Journal of Economic Geology, 1(1): 19–46 (in Persian with English abstract).

Nabavi, M.H., 1976. An introduction to the Iranian geology. Geological Survey of Iran, Tehran, 110 pp (in Persian).

Nakamura, N., 1974. Determination of REE, Ba, Fe, Mg, Na and K in carbonaceous and ordinary Chondrites. Geochimica et Cosmochimica Acta, 38(5): 755–773.

Parak, T., 1985. Phosphorus in different type of ore, sulfides in the iron deposits, and the type and origin of ores at Kiruna. Economic Geology, 80(3): 646–665.

Rahmani, Sh., 2010. Gold exploration of Lohneh-Zardeh area (1:25000), Tarom zone. Geological survey of Iran, Tehran, Report 121, 83 pp (in Persian).

Rolland, Y., Cox, S., Boullier, A.M., Pennacchioni, G. and Mancktelow, N., 2003. Rare earth and trace element mobility in mid-crustal shear zones: insights from the Mont Blanc Massif (Western Alps). Earth and Planetary Science Letters, 214(1–2): 203–219

Saeedi, A., 2015. Petrology and geochemistry of Aliabad Mousavi-Khanchy intrusions (Tarom area, Zanjan province) with considering on Cu mineralization. M.Sc. Thesis, University of Zanjan, Zanjan, Iran, 152 pp (in Persian with English abstract).

Wang, Q., Wyman, D.A., Xu, J.F, Zhao, Z.H., Jian, P., Xiong, X.L., Bao, Z.W., Li, C.F. and Bai, Z.H., 2006. Petrogenesis of Cretaceous adakitic and shoshonitic igneous rocks in the Luzong area, Anhui province (eastern China): Implications for geodynamics and Cu-Au mineralization. Lithos, 89(3–4): 424–446.

Whitford, D.J., Korsch, M.J., Porritt, P.M. and Craven, S.J., 1988. Rare earth element mobility around the volcanogenic polymetallic massive sulfide deposit at Que River, Tasmania, Australia. Chemical Geology, 68(1–2): 105–119.

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

Yilmaz, H., Oyman, T., Sonmez, F.N., Arehart, G.B. and Billor, Z., 2010. Intermediate sulfidation epithermal gold-base metal deposits in Tertiary subaerial volcanic rocks, Sahinli/Tespih Dere (Lapseki/western Turkey). Ore Geology Reviews, 37(3): 236–258.