Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

Mineralography, Structural and Textural Studies and Genesis of Zaker Iron - Apatite Deposit (Northeast of Zanjan)

Document Type : Original Research Paper

Authors
N. Khanmohammadi 1
A. Khakzad 2
J. Izadyar 1
1 Dep. of Geology, Faculty of Sciences, Zanjan University, Zanjan, Iran.
2 Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran
10.22071/gsj.2009.55669
Abstract
Zaker iron deposit is located in the northeast of Zanjan city and is a part of Tarom volcano – plutonic belt in Azarbaijan – West alborze structural zone. The main rocks of the area consist of folded volcanic - volcanoclastic rocks including breccia tuff, lapilli-tuff and andezitic – basaltic lava of Amand member of Karaj formation with Eocene age that folded. Plutonic rocks with probably Oligocene age with various lithology changing from quartzmonzodiorite, quartzmonzonite to quartzsyenite with NW-SE trend were intruded into the volcanic – volcanoclastic rocks. Fe-mineralization occurred in interval of plutons and volcanic - volcanoclastic rocks. The main ore mineral is magnetite – apatite with minor amounts of quartz and calcite. As well as magnetite- apatite mineralization, pyrite with minor amounts of chalcopyrite occurred in sulphide veinlets. The mineralization has been seen in five forms: veinlets of magnetite in form of stock- work, massive magnetite- apatite, banded magnetite- apatite, coarse grained magnetite- apatite veins and sulphide veinlets. Intrusion of ore deposit into host volcanic rocks, are associated with skarn metasomatism that form actinolite, talc, chlorite, phlogopite, quartze, calcite and epidote. Geothermobarometry for the skarn part, indicate that XCO2 is about 0.9, pressure of 2 kbar and the temperature is about 400-500 0C for metamorphic reactions. Detailed studies on textures and structures suggest the source of the iron from Zaker granitoid body and volcanic rocks are host rocks for iron deposit. Mineralography investigations are indicative of magmatic origin and show the best correlation with "Kiruna–type" iron ores.  
Keywords
Zaker
Azarbaijan –West Alborze structural zone
Magnetite – apatite
Skarn
Geothermobarometry
Kiruna
References
Daliran, F., 2002-  Kiruna- type iron  ores and "apatite" of the Bafq district iron, with an emphasis on the Ree geochemistry of their apatites; in porter, T.M.(Ed), Hydrothermal  iron oxide Copper- Gold and related deposits.  A Global perspective, V.Z; PGC publishing, Adelaide, P303-320.
Deer, W. A., Howie, R. A. & Zussman, J., 1962- Rock forming minerals. 5. Longman, Londan, 371pp.
Frietsch, R., 1978- On the magmatic origin of  iron ores  of the kiruna – type. Economic geology, V.37, P 478-483.
Loberg, B. E. H. & Horndahl, A. K., 1983-  Ferried geochemistry of Swedish Precambrian ores. Mineralium Deposita,V.18, P 121-128.       
Nasland, H. R., Agurirre, R., Dobbs, F. M., Henriquez, F. & Nystrom, J. O., 2000-   The Origin, emplacement and eruption of ore magmas. Internet. 
Nystrom, J. O. & henriquez, F., 1994- magmatic features of iron ores of the kiruna – type in chile and widen: ore textures and magnetite  geochemistry. Economic geology, V.89, P 820-839. 
Hirayama, 1966- Explanatorytext of the Tarom Quadrangle map 1:100000 GSI.
Redman, P. W. and O. Reilly, W., 1970, the synthesis and inversion of  nonstoichometric  titanomagnetites. Phys. Earth planet. Inter., 4, P 121-128. 
Scientific Quarterly Journal of Geosciences
Volume 19, Issue 76
Winter 2010
Pages 119-126