Document Type : Original Research Paper

Authors

1 PhD. Student, Faculty of Earth Sciences, University of Shahid Beheshti, Tehran, Iran

2 Associate Professor, Faculty of Earth Sciences, University of Shahid Beheshti, Tehran, Iran

3 Assistant Professor, Faculty of Sciences, University of Zanjan, Zanjan, Iran

Abstract

The Gazestan magnetite-apatite deposit is hosted within an upper Proterozoic-lower Cambrian volcanic-sedimentary sequence, known as Rizu series, in the Bafq district, Central Iran. The Gazestan deposit occurred in intensely altered felsic-intermediate subvolcanic and volcanic host rocks. Field observations, drill core logging, petrographic studies, as well as geochemical and XRD data are indicative of differences in alterations assemblages and temporal/spatial distribution of the alteration products, compared to other iron oxide-apatite deposits in the Bafq district. Unlike many other Bafq district iron deposits, sodic alteration is only locally developed. Similarly, Ca+Fe or actinolitic alteration is poorly developed in Gazestan. Chloritic and sericitic alterations are most closely associated with ore formation in Gazestan. Chlorite commonly associated with magnetite, quartz and calcite in the altered host rocks. The chemical composition of chlorite falls in pycnochlorite and clinochlore fields. Calculated temperature for chlorite formation varies between 324-236 ºC. Sericite occurred both as a proximal alteration in ore zones, and as a distal alteration product in the volcanic and subvolcanic host rocks. Calcic-iron alteration is poorly developed in Gazestan. Potassic alteration marked by development of K- as well as biotite is only locally developed in Gazestan. Boron metasomatism occurs as quartz-tourmaline bands and disseminated grains in altered rocks. The scarcity and local nature of sodic (albitic) and calcic-iron (actinolitic) alterations, and the widespread and proximal chlorite alteration suggest that, compared to most other iron deposits of the Bafq district, Gazestan formed at relatively lower temperatures and possibly shallower depths.

Keywords

Main Subjects

Abdel-Rahman, A., 1994- Nature of biotites from alkaline, calc-alkaline, and peraluminous magmas, J. Petrol. 35(2); 525–541.
Barton, M. D., 2014- Iron Oxide(–Cu–Au–REE–P–Ag–U–Co) Systems. In: Holland H.D. and Turekian K.K. (eds.) Treatise on Geochemistry Oxford: Elsevier, Second Edition 13, 513–536.
Beaufort, D., Rigault, C., Billon, S., Billault, V., Inoue, A., Inoue, S. and Patrier, P., 2015- Chlorite and chloritization processes through mixed-layer mineral series in lowtemperature geological systems – a review, Clay Minerals, V. 50, 497–523.
Bourdelle, F., Parra, T., Chopin, C. and Beyssac, O., 2013- A new chlorite geothermometer for diagenetic to low-grade metamorphic conditions. Contrib. Mineral. Petrol. 165, 723–735.
Collins, A. C., 2010- Mineralogy and Geochemistry of Tourmaline in Contrasting Hydrothermal Systems: Copiapo´ Area, Northern Chile, 225 p. Unpublished MS Thesis, University of Arizona.
Corriveau, L., Montreuil, J. F. and Potter, E. G., 2016- Alteration Facies Linkages Among Iron Oxide Copper-Gold, Iron Oxide-Apatite, and Affiliated Deposits in the Great Bear Magmatic Zone, Northwest Territories, Canada, Economic Geology, v. 111, pp. 2045–2072.
Daliran, F., 1990- The magnetite-apatite deposit of Mishdovan, East Central Iran. An alkali rhyolite hosted, "Kiruna-type" occurrence in the lnfracambrian Bafg metallotect: Heidelberg Geowiss Abh 37; 248 p.
Daliran, F., Stosch, H. G . and Williams, P., 2007- Multistage metasomatism and mineralization at hydrothermal Fe oxide-REE apatite deposits and "apatitites" of the Bafq District, Central-East Iran, in Andrew, C.J. et a!., eds., Digging Deeper, Proceedings of the 9th Biennial SGA Meeting Dublin 2007, p. 1501-1504.
Daliran, F., Stosch, H. G., Williams, P., Jamli, H. and Dorri, M. B., 2010- Early Cambrian Iron Oxide-Apatite-REE (U) Deposits of the Bafq District, East-Central Iran. In: Corriveau L, Mumin H (eds) Exploring for Iron oxide copper–gold deposits: Canada and Global analogues. Geol Assoc Canada, Short Course Notes 20; 143–155.
Deer, W. A., Howie, R. A. and Zussman, J., 1962- Rock-forming Minerals. Sheet Silicates. Longman, London, 270 pp.
Dora, M. L. and Randive, K. R., 2015- Chloritisation along the Thanewasna shear zone, Western Bastar Craton, Central India: Its genetic linkage to Cu–Au mineralization. Ore Geology Reviews 70; 151–172.
Enkin, R. J., Corriveau, L. and Hayward, N., 2016- Metasomatic Alteration Control of Petrophysical Properties in the Great Bear Magmatic Zone (Northwest Territories, Canada), Economic Geology, v. 111, pp. 2073–2085.
Förster, H. and Knittel, U., 1979- Petrographic Observation on a Magnetite Deposit at Mishdovan, Central Iran. Economic Geology, 74; 1485-1489.
Foster, M. D., 1962- Interpretation of the composition and a classification of the chlorites: U.S. Geological Survey Professional Paper 414-A. p. 33.
Haghipour, A., 1974- Etude geologique de Ia region de Biabanak-Bafg (Iran Central): petrographie et tectonique du socle Precambrien et de sa couverture: Unpublished thesis (Doctoral d'Etat), Universite de Grenoble, 403 p.
Haghipour, A., 1977- Geological Map of the Posht-e-Badam Area. Tehran, Geological Survey of Iran, scale 1: 500,000.
Hawthorne, F. C. and Henry, D. J., 1999- Classification of the minerals of the tourmaline group. European Journal of Mineralogy, 11; 201-215.
Heidarian, H., Alirezaei, S. and Lentz, D. R., 2017- Chadormalu Kiruna-type magnetite-apatite deposit, Bafq district, Iran: Insights into hydrothermal alteration and petrogenesis from geochemical, fluid inclusion, and sulfur isotope data, Ore geology Reviews, 83; 43-82.
Hitzman, M. W., Oreskes, N. and Einaudi, M. T., 1992- Geological characteristics and tectonic setting of Proterozoic iron oxide (Cu–U–Au–REE) deposits, Precambrian Research, 58; 241–287.
Hushmandzadeh, A. R., 1969- Metamorphisme et granitisation du massif Chapedony (Iran Central). Universite Scientifique et Medicale de Grenoble, France, 242 p.
Jami, M., 2005- Geology, geochemistry and evolution of the Esfordi phosphate-iron deposit, Bafq area, Central Iran; Ph.D. thesis, University of South Wales, 403p.
Jiang, W. T., Peacor, D. R. and Buseck, P. R., 1994- Chlorite geothermometry contamination and apparent octahedral vacancies. Clay Clay Miner. 42.
Khoshnoodi, Kh., Behzadi, M., Gannadi-Maragheh, M. and Yazdi, M., 2017- Alkali Metasomatism and Th-REE Mineralization in the Choghart deposit, Bafq district, Central Iran, Geologia Croatica, 70, No 1; 53-69.
Kranidiotis, P. and Maclean, W. H., 1987- Systematic of Chlorite Alteration at the Phelps Dodge Massive Sulfide Deposit, Matagami, Quebec, Economic Geology, 82; 1898-1911.
Mishima, T., Hirono, T., Soh, W. and Song, S. R., 2006- Thermal history estimation of the Taiwan Chelungpu fault using rock-magnetic methods. Geophys. Res. Lett. 33.
Nachit, H., Abderrahmane, I., El Hassan, A. and Mohcine, B. O., 2005- Discrimination between primary magmatic biotites, reequilibrated biotites and neoformed biotites, C. R. Geoscience 337; 1415–1420.
Nystrom, J. O. and Henriquez, F., 1994- Magmatic Features of Iron Ores of the Kiruna-type in Chile and Sweden: Ore textures and magnetite geochemistry, Eco. Geo., 89; 820-839.
Oliver, N. H. S., Cleverley, J. S., Mark, G., Pollard, P. J., Bin, Fu, Marshall, L. J., Rubenach, M. J., Williams, P. J. and Baker, T., 2004- Modelling the role of sodic alteration in the genesis of iron oxide-copper-gold deposits, eastern Mount Isa Block, Australia. Econ. Geol. 99; 1145-1176.
Putnis, A. and Austrheim, H., 2010- Fluid induced processes: metasomatism and metamorphism. Geofluids, 10; 254-269.
Rajabi, A, Rastad, E. and Canet, C., 2012- Metallogeny of Cretaceous carbonate-hosted Zn–Pb deposits of Iran: geotectonic setting and data integration for future mineral exploration. International Geology Review, 54; 1649-1672.
Ramezani, J. and Tucker, R. D., 2003- The Saghand region, Central Iran: U-Pb geochronology, petrogenesis and implications for Gondwana tectonics; American J. Sci. 303; 622–665.
Reed, M. H., 1997- Hydrothermal alteration and its relationship to ore fluid composition. In: Barnes, H.L. Ed., Geochemistry of Hydrothermal Ore Deposits. 3rd edn. Wiley, New York, NY, 303–365.
Robb, L. J., 2005- Introduction to ore forming processes (2005). Blackwell Publishing, Malden, 373 pp.
Samani, B., 1988- Metallogeny of the Precambrian in Iran, Precamb. Res., 39; 85–106.
Schiffman, P. and Fridleifsson, G. O., 1991- The smectite–chlorite transition in drillhole NJ-15, Nesjavellir geothermal field, Iceland: XRD, BSE and electron microprobe investigations. J. Metamorph. Geol. 9, 679–696.
Shabani, T. A. A., 2009- Mineral chemistry of chlorite replacing biotite from granitic rocks of the Canadian Appalachians. J. Sci. Iran 203, 265–275.
Stosch, H. G., Romer, R. L., Daliran, F. and Rhede, D., 2011- Uranium–lead ages of apatite from iron oxide ores of the Bafq District, East-Central Iran. Miner. Deposita. 46, 9–21.
Taghipour, S., Ali Kananian, A. K. and Somarin, A. K., 2013- Mineral chemistry and alteration parageneses of the Chogart iron oxide-apatite occurrence, Bafq district, Central Iran, N. Jb. Geol. Paleont. Abh. 269/3; 221–240
Torab, F. M. and Lehmann, B., 2007- Magnetite–apatite deposits of the Bafq district, Central Iran: apatite geochemistry and monazite geochronology. Mineral Mag 71:347–363
Torab, F. M., 2010- Geochemistry and radioisotope studies on the iron-apatite ores in Bafq metalogenic zone for determination of apatite origin; Iranian J. Crystallogr. Mineral., 18(3); 409–418 (in Persian, with English abstract(.
Whitney, D. L. and Evans, B. W., 2010- Abbreviations for names of rock-forming minerals. American Mineralogist 95: 185–187.
Williams, P. J., Barton, M. D., Johnson, D. A., Fontboté, L., de Haller, A., Mark, G., Oliver, N. H. S. and Marschik, R., 2005- Iron oxide copper-gold deposits: Geology, space-time distribution, and possible modes of origin. Econ. Geol. 100th Anniversary volume, 371–405.
Zane, A. and Weiss, Z., 1998- A procedure for classifying rock-forming chlorites based on microprobe data, Rendiconti Lincei, Volume 9, Issue 1, pp 51–56.