Journal of Economic Geology

325-354

Authors: Alireza Ghiasvand, Mohammad Hassan Karimpour, Azadeh Malekzadeh Shafaroudi and Mohammad Reza Haidarian Shahri

The Firouzeh mine is located in the Northwest of Neyshabour in the Khorasan Razavi province, Northeast of Iran, and eastern side of the Quchan-Sabzevar Cenozoic magmatic arc. Widespread magmatic activity in the Quchan-Sabzevar arc, is spatially and temporally associated with several types of mineralizations such as IOCG, Cu-Au porphyry and Kiruna types (Ghiasvand et al., 2016; Karimpour et al., 2011; Fatehi, 2014; Zarei et al., 2016). The aim of this investigation is to provide an understanding of the geology, alteration, mineralization, geochemistry, fluids evolution and genesis of the Firouzeh mine. Materials and methods Two hundred and fifty thin and polished sections were prepared for microscopic study. Twenty-nine samples were analyzed by X-ray fluorescence (XRF) method at the laboratory of Zar Azma company, Tehran, Iran. Twenty-one samples were analyzed by the X-ray Diffraction (XRD) method at the laboratory of Kansaran Binalood company, Tehran, Iran. Sixty samples were selected for 55-elemental analysis by composition of ICP-AES (Inductively coupled plasma atomic emission spectroscopy) and ICP-MS (Inductively coupled plasma Mass Spectrometry). Moreover, Sixty samples were selected for Au analysis by Aqua Regia Digestion at the SGS Laboratories, Canada. Six doubly polished sections of quartz mineralization were prepared for microthermometric analysis. Homogenization and last ice-melting temperatures were measured using a Linkam THMSG 600 combined heating and freezing stage at the Ferdowsi University of Mashhad. Result The Firouzeh mine contains various Middle-Eocene subvolcanic rocks as dykes which have intruded into Paleocene-Eocene volcanic rocks. Important altrations consist of silicified, argillic and carbonate among which silicified is the most extensive. Primary minerals are magnetite, specularite, pyrite, chalcopyrite and bornite and secondary minerals are hematite, alunite, covellite, turquoise and limonite. Mineralization has occurred in the cracks and fractures at the surface and in tunnels, mainly as disseminated, stockwork, vein-veinlet and hydrothermal breccia. Geochemical explorations showed anomalies of copper (up to ppm 1074), gold (up to ppb 699), iron (up to over percent 30), cerium (up to ppm 464), lanthanum (up to ppm 227), uranium (up to ppm 243) and cobalt (up to over ppm 10000) that has many similarities with IOCG type deposits (Corriveau, 2007; Zamora and Castillo, 2001; Marschik et al., 2000(. Fluid inclusions are relatively simple liduid+vapor types, with homogenization temperature from 147 to 278ºC and average temperature of 203ºC and Salinity containing 5.56 to 17.08 wt. percent NaCl equiv. which has resulted from fluids with KCl, CaCl2, MgCl2 and NaCl compositions. Mixing process between hot and saline fluid with cold and low saline fluid and also, boiling process can caused deposition of elements. Discussion Firouzeh mineral deposit has magmatic-hydrothermal source and is related to tertiary magmatic activities of subduction of Neothetys Sabzevar oceanic crust beneath the Turan crust. Fluid mixing has played an important role for precipitation during mineralization and includes the source of hot and saline magmatic fluids with high contents of metallogenic elements and the mixing with cold and low saline meteoric waters resulting in the formation of deposit (Bastrakov et al., 2007; Simard et al., 2006; Wilkinson, 2001; Beane, 1983). Based on geological characteristics, alteration, mineralization, geochemistry, geophysics and fluid inclusion studies, Firouzeh mine is a great mineralization of iron oxide copper-gold-U-LREE which has similarities to the hematite-dominant section of Olympic Dam IOCG deposit. Acknowledgments The Research Foundation of the Ferdowsi University of Mashhad, Iran, supported this study (Project No. 3/18303). We would like to thank the Iranian mineral processing research center and laboratories of Zar Azma, Kansaran Binalood, ACME and SGS. We also thank rural cooperation of Firouzeh mine for its liaison in field survey. References Bastrakov, E.N., Skirrow, R.G. and Davidson, G.J., 2007. Fluid evolution and origins of Iron Oxide Cu-Au prospects in the Olympic Dam district, Gawler craton, South Australia. Economic Geology, 102(8): 1415–1440. Beane, R.E., 1983. The Magmatic-Meteoric Transition. Geothermal Resources Council, California, Report 13, 253 pp. Corriveau, L., 2007. Iron oxide copper gold deposits: A Canadian perspective. In: W. Goodfellow (Editor), Mineral deposit of Canada: A synthesis of major deposit- types, district metallogeny, the evolution of geological provinces, and exploration methods. Geological Association of Canada Mineral deposits Division, Vancouver, pp. 307–328. Fatehi, H., 2014. Geology, mineralization and geochemistry of Jalambadan deposit, NW Sabzevar. M.Sc. Thesis, Ferdowsi University of Mashhad, Mashhad, Iran, 240 pp. (in Persian) Ghiasvand, A., Karimpour, M.H., Heidarian Shahri, M.R. and Malekzadeh Shafaroudi, A., 2016. Mineralization and ground magnetic survey for mineralization prospecting and identify of intrusive bodies in the Neyshabour Firouzeh mine, Khorasan Razavi province. Journal of Advanced Applied Geology, 20(6): 86–103. (in Persian) Karimpour, M.H., Malekzadeh Shafaroudi, A., Sfandiarpour, A. and Mohammadnejad, H., 2011. Neyshabour turquoise mine: The first IOCG-U-REE. Journal of Economic Geology, 2(3): 193–216. (in Persian) Marschik, R., Leveille, R.A. and Martin, W., 2000. La Candelaria and the Punta del Cobre district, Chile, Early Cretaceous iron oxide Cu-Au (-Zn-Ag) mineralization. In: T.M. Porter (Editor), Hydrothermal iron oxide copper-gold and related deposits, A global perspective. Australian Mineral Foundation, Adelaide, pp. 163–175. Simard, M., Beaudoin, G., Bernard, J. and Hupe, A., 2006. Metallogeny of the Mont-de-l’Aigle IOCG deposit, Gaspé Peninsula, Québec, Canada. Mineralium Deposita, 41(6): 607–636. Wilkinson, J.J., 2001. Fluid inclusions in hydrothermal ore deposits. Lithos, 55(1–4): 229–272. Zamora, R. and Castillo, B., 2001. Mineralizacio´ n de Fe-Cu-Au en el distritoMantoverde, Cordillera de la Costa, III Regio´n de Atacama, Chile. Proc 2ndCongrInt de Prospectores y Exploradores, Inst de Ingenieros de Minas del Peru´, Lima, Peru. Zarei, A., Malekzadeh Shafaroudi, A. and Karimpour, M.H., 2016. Geochemistry and genesis of iron-apatite ore in Khanlogh deposit, eastern Cenozoic Quchan-Sabzevar magmatic arc, NE Iran.Acta Geologica Sinica, 90(1): 121–137.

381-402

Authors: Mohsen Mobasheri, Fardin Mousivand and Mojtaba Rostami Hussory

Introduction Bauxite deposits in Iran are dominantly hosted by Late Triassic-Early Jurassic sequences in the Alborz zone and Late Cretaceous in the Zagros zone (e.g., Zarasvandi et al., 2008). Metamorphosed bauxite deposits in Iran are very rare, such as Heidarabad corundum-rich deposit (Emamali-pour, and Mirmohammadi, 2011). The Qale-Kham ore deposit is the first report of bauxite mineralization in the Early Paleozoic sequences of Sanandaj- Sirjan zone. In southeastern Sirjan (Qale-Kham area), karstic pockets of Late-Cambrian metabauxites embedded in carbonate rocks. The corundum-rich metabauxites are very rare in the world. Bauxite deposits can be classified into three main groups: lateritic, sedimentary and karstic-types. The karstic bauxite deposits have formed on the paleokarstic surface of carbonates (Bárdossy, 1982; Bárdossy and Aleva, 1990; Bogatyrev et al., 2009). The aim of this paper is to discuss genesis of the Qale-Kham bauxite deposit based on geological, petrographic, mineralogical and geochemical evidences. Materials and Methods A number of 95 samples were collected from the bauxite lenses in the Qale-Kham ore deposit. Optical microscopic investigations were conducted on 40 thin sections, 35 thin-polished sections and 20 polished sections of the samples using a Zeiss optical microscope equipped at the Shahrood University of Technology. Mineralogical analyses were done by X-ray diffractometer equipped with a CuKα tube and monochrometer (XRD Philips PW 1800) at the Kansaran Binaloud Company. The concentration of the major elements in the samples was determined using a wavelength X-ray fluorescence spectrometer (XRF Philips PW 1480) at the Kansaran Binaloud Company. Discussion In the Qale-Kham area, the rock units consist of amphibolite, mica schist, chlorite schist, epidotic schist and marble. The ores are mainly massive; however, pisolitic texture was observed in the deposit. Detailed mineralogical analyses of the Qale-Kham metabauxite deposit have been performed by optical microscopy and X-ray diffraction (XRD) studies. XRD results show that ore at the metabauxite deposits is composed of corundum, diaspore, chloritoid, opaque minerals (magnetite, hematite, ilmenite, and rutile), white mica (margarite, muscovite), goethite and limonite. Mineralogy of ores (such as corundum) and textures are representative of the impact of a metamorphic event on bauxite ores. This metamorphism and deformation has created structures, textures and formation of new minerals such as corundum and magnetite in the Qale-Kham ore deposit. The ores are mainly composed of Al2O3 (25–58%), SiO2 (3–15%), Fe2O3 (15–34%) and TiO2 (2–5%). Alkalis and alkali earth elements show low values, probably because these elements are highly mobile and have usually leached out during chemical weathering (Gu et al., 2013). The triangular variation diagrams of Al2O3–SiO2–Fe2O3 are commonly used to show the degree of lateritization, mineral control and bauxite classification. Based on the mineralogical classification of Aleva (1994), most of the bauxite samples in the studied areas fall within the bauxite and ferritic bauxite fields. The chemical composition of corundum-rich metabauxites in Qale-Kham is nearly similar to those of other karst bauxite and karstic metabauxite such as corundum-rich metabauxites of the Menderes Massif (e.g., Özlü, 1983). They show generally strong enrichment in Al2O3, Fe2O3 and strong depletion in K2O, Na2O contents. Overal, the studied corundum-rich metabauxites at Qale-Kham can be classified as karstbauxites based upon their geological, mineralogical and geochemical characteristics. Results Corundum-rich metabauxite of Qale-Kham in the best outcrop is located at the SE Sirjan town. The metabauxite formed in the Paleozoic metamporphosed carbonate sequences of the South Sanandaj-Sirjan zone as karst-type deposits. Based on petrological and X-ray studies, the Qale-Kham ores consist of corundum, diaspore, chloritoid, opaque minerals (magnetite, hematite, ilmenite and rutile), white mica (margarite and muscovite), goethite and limonite. These studies suggest that the Qale-Kham ore deposit has been formed under suitable climatic conditions in the late Cambrian. This deposit has been metamorphesd and deformed due to the effect of early Cimmerian orogenic movements. References Aleva, G.J.J., 1994. Laterites: concepts, geology, morphology and chemistry. International Soil Reference and Information Centre (ISRIC), Wageningen, Netherlands, 169 pp. Bárdossy, G., 1982. Karst bauxites. Elsevier, Amsterdam, 441 pp. Bárdossy, G. and Aleva, G.J.J., 1990. Lateritic bauxite. Elsevier, Amsterdam, 624 pp. Bogatyrev, B.A., Zhukov, V.V. and Tsekhovsky, Y.G., 2009. Formation conditions and regularities of the distribution of large and superlarge bauxite deposits. Lithology and Mineral Resources, 44(2): 135–151. Emamali-pour, A. and Mirmohammadi, M.S., 2011. Mineralogy and geochemistry of corundum-bearing metabauxite- laterite from Heydarabad, SE Urmia, NW Iran. Iranian Journal of Crystallography and Mineralogy, 19(1): 59–72. (in Persian with English abstract) Gu, J., Huang, Z., Fan, H., Jin, Z., Yan, Z. and Zhang, J., 2013. Mineralogy, geochemistry, and genesis of lateritic bauxite deposits in the Wuchuan–Zheng'an–Daozhen area, Northern Guizhou Province China. Journal of Geochemical Exploration, 130(6): 44–59. Özlü, N., 1983. Trace-element content of ‘Karst Bauxites’ and their parent rocks in the Mediterranean Belt. Mineralium Deposita, 18(3): 469–476. Poosti, M., Khakzad, A. and Fadaeian, M., 2011. Bauxite and deposits in Iran. University of Hormozgan, Hormozgan, 229 pp. Zarasvandi, A., Charchi, A., Carranza, E.J.M. and Alizadeh, B., 2008. Karst bauxite deposits in the Zagros Mountain Belt, Iran. Ore Geology Reviews, 34(4): 521–532.

425-448

Authors: Reza Monazzami Bagherzadeh, Mohammad Hassan Karimpour, G. Lang Farmer, Charles R. Stern, Jose Francisco Santos, Sara Ribeiro, Behnam Rahimi and Mohammad Reza Haidarian Shahri

Introduction The study area is located in the northeast of Iran (the Khorasan Razavi province) and 28 km northwest of Bardaskan city and in position of 57˚ 46΄ to 57˚ 52΄ latitude and 35˚ 21΄ to 35˚ 24΄ longitude. The study area is a part of Taknar zone. The Taknar geological-structural zone is situated in the north Central Iranian microcontinental and it is a part of Lut block (Fig.1). Taknar plutonic complex that is situated in the Taknar structural zone is located in the northern part of Iranian microcontinent. Materials and methods Chemical analysis of REE and minor elements of samples of the Bornaward diorites and gabbro’s took place in the ACME Lab. in Vancouver, Canada, by the ICP-MS method (Table. 1). For the Bornaward diorite dating by the U-Pb method, zircon grains of material remaining in the sieve, Bromoform were isolated from light minerals by cleaning and were isolated with a minimum size of 25 microns, and then studies took place in the Crohn's Laser Lab Arizona (Gehrels et al., 2008). Measurement of Rb, Sr, Sm and Nd isotopes and (143Nd/144Nd)i , (87Sr/86Sr)i ratios and ƐNd (T=552), ƐNd (T=0), ƐSr (T=552) and ƐSr (T=0) took place in radioisotope Laboratory, University of Aveiro in Portugal. Discussion Geology of study area The study area forms the central part of the Bornaward plutonic complex. This complex is a granitoid assemblage including granite, granodiorite, tonalite and granophyre.tscentral part has been formed by intermediate and basic intrusive rocks such as diorite, quartz diorite and gabbro units (Fig. 2). From the genetic point of view, the intermediate and mafic rocks of the Taknar plutonic complex does not have any relationship with granitoid rocks of this assemblage, and they are related to a similar magmatic phase but are separated from this granitoid assemblage. However, these mafic and intermediate units are older than granitic units at the rim of the complex that are called Bornaward granite. Petrography The main minerals in the diorite and quartz diorite rocks are plagioclase and hornblende and we can see biotite in the quartz dioritic rocks. Quartz exist as tiny grains and anhedral and in the matrix rock. The amount of Quartz in the quartz diorites is 5 to 20%. Plagioclases usually have normal zoning and are highly altered to sericite. Most of the plagioclases were saussuritized. Altered minerals resulted from plagioclase and hornblende are sericite, epidote, chlorite, zoisite and clinozoisite. The main minerals in the gabbro are pyroxene, hornblende, and fine grains plagioclase. Minor minerals in the rocks are apatite, magnetite and other opaque. The main texture of intermediate and mafic rocks in this assemblage is medium granular to coarse grain and especially in the intermediate rocks and gabbro rocks, we can see scattered poikilitic, intersertal, sub-ophitic and porphyroid texture. Geochemistry The area diorite and gabbro is located locate in Tholeiitic and Calc-alkaline series (Fig. 9). Shand index (Al2O3/(CaO+Na2O+K2O)) is obtained under 1.1, in Metaluminous field (Fig. 7) and I-type granite field (Chappell and White, 2001). Based on the TAS diagram (Middlemost, 1985), all the diorite and gabbro samples are located in diorite, gabbro-diorite and gabbro-norite groups (Fig. 6). The diorite and gabbro’s show enrichment LREE and low ascending pattern ((La/Yb)N =1.40-6.12 and LaN =12.26-75.81). U-Pb zircon geochronology Measurement of U-Th-Pb isotopes of the Bornaward diorite zircons of BKCh-03 sample (Table 2) show that its age is related to 551.96±4.32 Ma ago (Upper Precambrian (Neoproterozoic) (Ediacaran) (Fig. 14). Sr-Nd isotopes The (87Sr/86Sr)i and (143Nd/144Nd)i content of Bornaward diorite and gabbro rocks is located in the range of 0.7038 to 0.7135 and 0.51203 to 0.51214, respectively (Tables 3 and 4). It shows that the diorite and gabbro rocks can be affected by hydrothermal alteration because their (87Sr/86Sr)i is above (Fig. 16). The numeral amounts of ƐNd(T=552) of Bornaward diorite and gabbro are 2.0 to 4.0. Petrogenesis The Bornaward diorite and gabbro rocks show a widespread enriched pattern of Rb, U, K, Pb, La and Th elements than chondrite, while Ba, Ti, Ta, Sr and Nb elements show reduction as a result of fractional crystallization (Fig. 11). The rocks of this complex are formed at the continental margin and VAG environment (Fig. 18) which is related to the subduction of the oceanic crust that exists between the Iranian microcontinent and the Afghan Block. Results This assemblage with age of Late Neoproterozoic is the result of extensive magmatism in the northern part of the Iranian microcontinent due to Katangahi orogeny event. The similar magmatism in the northern part of the Iranian microcontinent is existing as Khaf-Kashmar-Bardeskan volcano-plutonic belt. Based on the geochemical investigations, the magmatism of these rocks has been tholeiitic and calk-alkaline and have formed the coexistent rocks with I-type granites. Alumina saturation index for intermediate and mafic rocks of Bornaward complex is metalumina. These are medium-K rocks and enriched in the LILE such as Rb, Pb, U and Th while depleted of the Nb, Ti, Ta, Sr and Ba. Therefore, it shows that these rocks have resulted from the mixing by the lower crust. The low (87Sr/86Sr)i Bornaward diorite and gabbro rocks and the numeral amounts of Ɛ0Nd(present) of these rocks from -0.2 to 4.0 show that production of such intrusive masses can be attributed to the source of upper mantle or contaminated lower continental crust. Environment of formation of the intermediate and basic rocks of the Bornaward plutonic complex is active continental margin and volcanic arc environment. References Chappell, B.W. and White, A.J.R., 2001. Two contrasting granite types: 25 years later. Australian Journal of Earth Sciences, 48(4): 489–499. Gehrels, G.E., Valencia, V.A. and Ruiz, J., 2008. Enhanced precision, accuracy, efficiency, and spatial resolution of U–Pb ages by laser ablation– multicollector– inductively coupled plasma-mass spectrometry. Geochemistry, Geophysics, Geosystems, 9(3): 1–13. Middlemost, E.A.K., 1985. Magmas and Magmatic Rocks. An Introduction to Igneous Petrology. Longman, London, New York, 266 pp.

471-496

Authors: Saleh Deymar, Mehrdad Behzadi, Mohammad Yazdi and Mohammad Reza Rezvanianzadeh

Introduction The Saghand mining district is a part of Bafq-Saghand metallogenic zone in the Central Iranian geostructural zone which is located in northeast of city of Yazd. This area is known to be more susceptible to mineralization of U and Th radioactive elements, but in fact is that its main importance is for relatively large iron deposits. However, in this region similar to some of the ore deposits within the Bafq area, rare earth elements have a high anomaly. Alkali-metasomatism occurs in a large variety of environments and geological periods. It can be spatially associated with ore deposits, as for some IOCG deposits or exists in barren systems such as metasomatism within the ocean crust (Johnson and Harlow, 1999). Although average U and REEs contents of the ore bodies associated with alkali-metasomatism are not high, they represent a promising exploration target because the resources of such deposits are relatively large (Cuney et al., 2012). The alkali-metasomatism could take place in all kinds of rocks. In addition to wide distribution in granite and granodiorite, it could be also identified in all kinds of metamorphic rocks, pegmatites, subvolcanic and volcanic rocks, and they all have mineralization (Zhao, 2005). Materials and methods After field studies, host rocks and metasomatites were sampled from outcrops, trenches, and core drillings. Since the rare earth elements and radioactive elements are present within the same mineralogy (Samani, 1985), surface spectrometry measurements were used in the selection of appropriate samples. For microscopic studies, 210 samples were prepared and studied. Ore minerals were investigated in polished and polished thin sections using optical microscope and Scanning Electron Microscopy (SEM) analysis was done in the Iranian Mineral Processing Research Center. An LEO-1400 SEM with energy dispersive X-ray spectrometry and back-scatter electron (BSE) imaging capabilities was used (accelerating voltage, 17-19 kV, and beam current of 20 nA). The 16 samples were analyzed by the ICP-MS method at Zarazma Mineral Studies Company, Iran, for major and trace elements at the various radiations and lithological ranges. The detection limit and precision for determination of REE, U and Th concentration were 0.2 to 1 ppm and 1 to 0.1 ppm, respectively. Discussion and results Based on field evidence and microscopic studies, four main stage of metasomatism with continuous evolution have been distinguished in the Saghand area, including: 1) Na-metasomatism, 2) Ca-Mg metasomatism, 3) K-metasomatism, and 4) Epidote±chlorite±calcite±quartz vein and veinlets. All metasomatic zones are generally enriched in U and REE and compared with the host rocks but economic grades are less widespread and limited to Ca-Mg metasomatite zones near pinkish to red color albitites. The major Ti-REE-U(Th) minerals are davidite and brannerite, which have mainly crystallized during the Ca-Mg metasomatic stage. Ti or Ti-bearing minerals as paragenesis with davidite and brannerite are also deposited in amphibole-albite metasomatic zones. All these minerals are usually fractured and along fractures and its margin is replaced by titanite, leucoxene and rutile. In this study, geochemical analysis results of igneous rocks in the Saghand ore deposit, confirm the active continental margin arc setting and the nature of calc-alkaline magmatism in the region. The good adaptation of the REEs patterns in granites with the quartzdiorite-diorite rocks, can be a strong reason for their common tectono-magmatic origin. This Geodynamic environment had been the appropriate background in terms of protolith, heat engine for metasomatism cycle and supply hydrothermal solution and controlling structural pathways. The proximity of mineralized metasomatic rocks with the granitic rocks and intrusion of the granite apophysises into the metasomatic rocks, mobility of REE elements in the metasomatic environments, adaptation of geochemical properties of REE, U and Th elements in the mineralized metasomatitic rocks with the granitic rocks and finally, there was no evidence of intrusion of unusual magmas such as the carbonatite or alkaline magmas at the current level of ore deposit outcrops. Thesesuggest a close relationship between mineralization and metasomatic events with the granite intrusion. Fluids differentiated from the Douzakh-Darreh granite have entered the fault and crushed zones in a tectonically active regime of marginal continental arc. Due to reaction of the high temperature fluid with the protolith rocks, the ratios of Na+/K+ and Na+/H+ in fluid in equilibrated to feldspars of protolith rock elevated (Cuney et al., 2012). A basically alkaline medium to low temperature hydrothermal fluid is a suitable environment for the activation and transfer of U and REE in the form of hydroxyl complex (Romberger, 1984). Conversely, Th remained essentially immobile during the metasomatic processes (Cuney et al., 2012) and therefore, cannot be in abundance carried by this fluid. Hematite pigmentation of albite and transfer of U shows that oxygen fugacity in the early hydrothermal fluid has been quite high. These geochemical conditions simply allow U, and REEs enter from wall rocks to fluids and form hydroxyl complex of these elements, which are sustainable and are portable. Titanium bearing minerals within the quartzdiorite-diorite rocks and Douzakh Dareh granite easily decompose under hydrothermal activity and form titanium hydroxides, which is a very strong absorbent for U. After mineralization of albite and hematite, oxidation degree of fluid quickly drops and as a result, conditions for instability of complexes containing Ti, REE and U are provided. Acknowledgements This paper is based on a part of the first author's Ph.D thesis at Shahid Beheshti University. This research was also supported by Skam Company and Iranian Mines & Mining Industries Development & Renovation Organization. References Cuney, M., Emetz, A., Mercadier, J., Mykchaylov, V., Shunko, V. and Yuslenko, A., 2012. Uranium deposits associated with Na-metasomatism from central Ukraine: A review of some of the major deposits and genetic constraints. Ore Geology Reviews, 44(1): 82–106. Johnson, C.A. and Harlow, G.E., 1999. Guatemala jadeitites and albitites were formed by deuterium-rich serpentinizing fluids deep within a subduction zone. Geology, 27(7): 629–632. Romberger, S.B., 1984. Transport and deposition of uranium in hydrothermal systems at temperatures up to 300 °C: geological implications. In: B. DeVivo, F. Ippolito, G. Capaldi and P.R. Simpson (Editors), Uranium Geochemistry, Mineralogy, Geology, Exploration and Resources. Institution of Mining and Metallurgy, London, pp. 12–17. Samani, B., 1985. Preliminary study of ore samples from the Saghand area (Central Iran). Atomic Energy Organization of Iran, Tehran, Report 168, 17 pp. (In Persian) Zhao, F., 2005. Alkali-metasomatism and uranium mineralization. 8th Biennial meeting, Society for Geology Applied to Mineral Deposits; Mineral deposit research meeting the global challenge, Beijing, China.

537-559

Authors: Mozhdeh Davoodifard, Giti Forghani Tehrani, Hadi Ghorbani and Habibollah Ghasemi

Introduction Pollution of soils with potentially toxic elements (PTEs) is one of the most important hazards threatening the health of natural ecosystems. In recent decades, the anthropogenic activities have led to the disruption of the geochemical and biochemical circles of these elements. Mining activities are one of the most important anthropogenic sources for PTEs. The mine tailings are the most important pollution sources of surrounding soils and groundwater (Ferreira da Silva et al., 2004; Boularbah et al., 2006). Indeed, agricultural activities have a significant impact on the soil pollution with PTEs (Keskin, 2010). Soil plays a vital role in human life. Thus, the monitoring and assessment of soils pollution is of great importance. The Irankuh Pb-Zn mine, located in the SW of Esfahan, is one of the most important mines of Iran. Mining and subsequent processing of ores in this region generates high volumes of mine wastes which are deposited near the mine site. On the other hand, agricultural activities in the Irankuh area are extensive and the mine's tailing ponds usually neighbor the farms. The present study aims to investigate the concentration, mobility and availability of PTEs in the Irankuh mine tailings and to determine the source of these pollutants in the surrounding soils. Material and Methods After the preliminary field studies, 28 soil samples including 8 mine- and 20 agricultural soils as well as two representative tailing samples were collected. One manure sample was also collected to identify the impact of agricultural activities on the concentration of PTEs in the soils, if any. First, the soil samples were air-dried at room temperature. Then, the large fragments and plant residuals were removed from the samples and the remaining portion was passed through a 2 mm stainless steel sieve. The sieved samples were ground to about 0.074 mm using an agate mortar and pestle and finally stored in polyethylene bags prior to laboratory analysis. The total concentrations of elements were measured by ICP-OES instrument after digesting by strong acids. The five-stage method of Tessier et al. (1979) was employed for sequential extraction analysis. In order to assess the pollution of the soils and tailings, the enrichment factor was calculated. Having obtained the results of the analysis, descriptive and multivariate data analyses were conducted. Results and discussion The average concentration of Ag, As, Ba, Cd, Co, Mn, Pb, Sb and Zn in the mine soils are higher than the agricultural soils. The application of manure to the agriclutural soils led to increase in Cu and Cr concentration of the soils; the high concentration of these two elements in the manure sample is indicative. The concentration of Ag, As, Cd, Ba, Pb, Ni, Zn and Sb in both agricultural and mine soils are higher than the average world soil composition (Kabata-Pendias, 2011), pointing to the impact of anthropogenic activities on the PTEs concentrations in the soils. The tailing samples are highly encirched with respect to As, Cd, Cu, Sb, Mn, Pb and Zn. Enrichment factor values confirms pollution of soils with respect to Ag, As, Cd, Pb, Sb and Zn. Tailing samples are also extremly contaminated by these elements. On the basis of the analysis of variance, there is a significant statistical difference between the element concentrations in mine and in agricultural soils. The cluster analysis indicates the impacts of mining activity on the PTEs concentrations in soils. On the basis of principal component analysis, the elements originate from three sources: 1- geogenic stable elements 2- anthropogenic elements and 3- the weathering products of carbonate units. Total concentrations of PTEs provide no information on their likely environmental impacts. The speciation studies through sequential extraction analysis could be used to determine the mobility and availability of PTEs. By employing sequential extraction procedure, it is possible to predict occurrence manner, mobility, solubility, bioavailability, toxicity and transport as well as the origin of PTEs (Favas et al., 2011). The results show that, on the average, 24.9, 20.3, 18.6, and 15.2 % of Cu, Mn, Cd and As, respectively, are present as exchangeable fraction. Therefore, the weathering of mine tailings may increase the bioavailability of these elements in agricultural soils and groundwater around the mining area. The mobility of arsenic and iron is lower than other studied elements. Chromium and nickel are not mobile. Acknowledgement This research has been funded by the Research Office of the Shahrood University of Technology. References Boularbah, A., Schwartz, C., Bitton, G. and Morel, J.L., 2006. Heavy metal contamination from mining sites in South Morocco: 1. Use of a biotest to assess metal toxicity of tailings and soils. Chemosphere, 63(5): 802–810. Favas, P.J.C., Pratas, J., Gomez, M.E.P. and Cala, V., 2011. Selective chemical extraction of heavy metals in tailings and soils contaminated by mining activity. Journal of Geochemical Exploration, 111(3): 160–171. Ferreira da Silva, E., Zhang, C., Serrano Pinto, L., Patinha, C. and Reis, P., 2004. Hazard assessment on arsenic and lead in soils of Castromil gold mining area, Portugal. Applied Geochemistry, 19(6): 887–898. Kabata-Pendias, A., 2011. Trace Elements in Soils and Plants. Chemical Rubber Company Press, BocaRaton, Florida, 413 pp. Keskin, T., 2010. Nitrate and heavy metal pollutin resulting from agricultural activity: a case study from Eskipazar (Karaabuk, Turkey). Environmental Earth Sciences, 61(4): 703–721. Tessier, A., Campbell, P.G.C. and Bisson, M., 1979. Sequential extraction procedure for the speciation of particulate trace metals. Analytical Chemistry, 51(7): 844–851.

587-616

Authors: Mahin Rostami and Ebrahim Tale Fazel

Introduction Ore deposits of the Bafq-Saghand metallogenic province (IRAN) with Proterozoic age represent that they belong to classic genetic model for hydrothermal iron oxide (Cu, Au, U, REE) deposits, which is widely referred to as iron oxide copper-gold (IOCG) and iron oxide-apatite (IOA) deposits (Samani, 1988; Daliran et al., 2007; 2010; Jami et al., 2007; Nabatian et al., 2015; Rajabi et al., 2015). According to the structural zone of Iran, the Bafq mining district is part of Central Iran and therein Kashmar-Kerman tectonic zone (Zarigan-Chahmir basin), and Lake Siah deposit occurs in Early Cambrian Volcano-Sedimentary Sequence (ECVSS). According to Förster et al. (1988) and Torab (2008), the Bafq mining district is composed of a huge volcanic suite in which sedimentary structures, fossils, and even glassy volcanics a surprisingly are well preserved. Calderas are important features in all volcanic environments and are commonly the sites of geothermal activity and mineralization (Cole et al., 2005). The Lake Siah iron±apatite deposit is located between Kusk and Esfordi deposits and 40 km northeastern Bafq (31°46´47 N and 55°42´56 E). Materials and methods A total of 50 samples were collected from the Lake Siah mine district. Ten samples of least-altered igneous rocks were analyzed for major, trace and rare earth elements by inductively coupled plasma spectrometry (ICP-MS), and X-ray fluorescence (XRF) at the Acme laboratory (Canada). The detection limit for major oxide analysis is 0.01%. Electron microprobe analyses (EMPA) and backscattered electron (BSE) images of minerals were obtained using a Cameca SX100 electron microprobe at the Iran Mineral Process and Research Center (IMPRC). An accelerating voltage of 15 to 25 kV and beam current of 20 mA was used for all analyses. Results and discussion The Lake Siah deposit with a covering area of about 5 km2 is located in the Central Iran Block and therein Kashmar-Kerman tectonic zone (Zarigan-Chahmir basin). The Nb/Y versus Zr/TiO2 diagram shows a typical trend from rhyolite and evolving to andesite/trachyandesite compositions, with few data plotting in the dacite/rhyodacitic rocks. Most of the igneous rocks plot within the high-potassic calc-alkaline to shoshonitic fields in the Th/Yb versus Ta/Yb diagram (Pearce, 1983). All studied rocks show similar incompatible trace element patterns with an enrichment of large ion lithophile elements (LILE: K, Rb, Ba, Th) and depletion of high field strength elements (HFSE: Nb and Ti), which are typical features of magmas from convergent margin tectonic settings. The Lake Siah deposit is composed of the hematite and magnetite as major minerals and apatite, goethite, pyrite and chalcopyrite as minor minerals. The deposit is controlled by NE-SW normal faults and occurs within early Cambrian trachyte, trachyandesite and rhyolite of the Lake Siah caldera. Intermediate argillic, sodic (albitic), silisic, potassic-calcic, hydrolytic (acidic), and sodic-calcic (Fe) alterations occur near the ore deposit. Lipman (1992) identifies a number of stages in the development of a caldera which includes: 1) pre-collapse volcanism, 2) caldera subsidence, 3) post-collapse magmatism and resurgence, and 4) hydrothermal activity and mineralization. Flow of dacite and andesite into the shallow magmatic system is facilitated by regional fault systems which provide pathways for magma ascent. Dacite and remobilized rhyolite rise buoyantly to form domes by collapse of the chamber roof and producing surface resurgent uplift. The resurgent deformation caused by magma ascent fractures the chamber roof, increasing its structural permeability and allowing rhyolite magmas to intrude and/or cause eruption. Explosive eruption of high viscosity magma is the cause of creating fractures and breccia in the host rocks and facilitated percolation Fe-P bearing magmatic fluids. References Cole, J.W., Milner, D.M. and Spinks, K.D., 2005. Calderas and caldera structures: a review. Earth Science Reviews, 69(1): 1–26. 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: C.J. Andrew (Editor), Proceedings of the 9th Biennial Society for Geology Applied meeting, The Society for Geology Applied, Dublin, pp. 1501–1504. Daliran, F., Stosch, H.G., Williams, P., Jamali, H. and Dorri, M.B., 2010. Early Cambrian iron oxide- apatite-REE (U) deposits of the Bafq District, east-central Iran. In: L. Corriveau and H. Mumin (Editors), Exploring for Iron Oxide Copper–gold deposits: Canada and global analogues. Geological Association of Canada, Canada, pp. 147–160. Förster, H., Knittel, U. and Sennewald, S., 1988. Resurgent cauldrons and their mineralization, central Iran. Economic Geology, 74(6): 1485–1510. Jami, M., Dunlop, A.C. and Cohen, D.R., 2007. Fluid inclusion and stable isotope study of the Esfordi apatite–magnetite deposit, Central Iran. Economic Geology, 102(6): 1111–1128. Lipman, P.W., 1992. Ash-flow calderas as structural controls of ore deposits-recent work and future problems. United State Geological Survey Bulletin, 104(2): 32–39. Nabatian, G., Rastad, E., Neubauer, F., Honarmand, M. and Ghaderi, M., 2015. Iron and Fe-Mn mineralization in Iran: implications for Tethyan metallogeny. Australian Journal of Earth Siences, 62(2): 211–241. Pearce, J.A., 1983. Role of the sub-continental lithosphere in magma genesis at active continental margins. In: C.J. Hawkesworth and M.J. Norry (Editors), Continental Basalts and Mantle Xenoliths. The Royal Society, London, pp. 230–249. Rajabi, A., Canet, C., Rastad, E. and Alfonso, P., 2015. Basin evolution and stratigraphic correlation of sedimentary-exhalative Zn-Pb deposits of the Early Cambrian Zarigan-Chahmir Basin, Central Iran. Ore Geology Reviews, 64(1): 328–353. Samani, B., 1988. Metallogeny of the Precambrian in Iran. Precambrian Research, 39(1): 85–106. Torab, F.M., 2008. Geochemistry and metallogeny of magnetite-apatite deposits of the Bafq mining district, central Iran. Unpublished Ph.D. Thesis, Technical University of Clausthal, Clausthal, Germany, 131 pp.

639-375

Authors: Moslem Fatehi and Hooshang Asadi Haroni

Introduction Geophysical exploration is an inexpensive, fast and efficient tool to provide valuable information about the sub-surface geological complications (Dentith and Mudge, 2014). Modern geophysical methods are widely used to identify and characterize porphyry copper deposits on various scales (Holden et al., 2011; Hoschke, 2011; Clark, 2014). It is often an indirect exploration method; therefore, an accurate data interpretation is required to extract the proper information associated with mineralization (Clark, 2014). For efficient interpretation of geophysical data in mineral exploration, it is initially important to understand the geological properties of a deposit (i.e., host rock, hydrothermal alteration system, mineralogical characteristics, texture, structural controls, zones of outcropping mineralization, etc.). Then, according to these properties and other genetic information, a conceptual model is defined to choose the proper exploration criteria and geophysical exploration methods to identify real anomalies associated with mineralization. Finally, the geophysical data are interpreted by considering the physical properties of the conceptual model. The conceptual model and the interpretation of geophysical data could be updated by using the new information acquired from the exploratory boreholes. This paper discusses the effectiveness of several geophysical methods in exploration of gold-rich porphyry copper deposits, and presents the exploration models related to the geophysical features of such deposits. We mostly used the related papers published in the same field to prepare these models. Then, on the basis of the defined geophysical signatures of the porphyry deposits, the IP&RS and magnetic data of the Dalli Cu-Au porphyry deposit were interpreted. Materials and methods Porphyry deposits are the most important source of copper, molybdenum and rhenium (Sillitoe, 2010) and provide significant amount of gold, silver and some other metals (Cooke et al., 2014). These are intrusion- related deposits which are geometrically symmetrical and are affected by different hydrothermal potassic, phyllic, argillic and propylitic alterations that often show a spatial zonation. Copper-gold mineralization mostly occur in the potassic alteration zone within the contact of the intrusive body and its adjacent wall rock. The physical properties of minerals and hydrothermal alterations associated with porphyry deposits near the surface are very variable, and therefore allow the use of various geophysical methods for exploration of such deposits. In porphyry deposits, sulfide minerals are present in different alteration zones with varying abundance, which could provide the use of electrical resistivity (RS) and induction polarization (IP) surveys to detect them. In gold-rich porphyry copper deposits, phyllic alteration zone often contain sulfide mineralization, therefore, this zone could be identified by high chargeability anomalies and low resistivities in the induced polarization surveys. The potassic alteration zone also contains sulfide minerals and is characterized in IP data with moderate to high-chargeability values. The IP method is the most extensively used geophysical approach in exploration of porphyry deposits. Magnetic minerals are enriched and destroyed respectively in potassic and phyllic alteration zones. Therefore, a high circular or elliptical magnetic anomaly is detected at the potassic alteration zone and is surrounded by a low magnetic anomaly related to the phyllic alteration zone. Hence, the airborne and ground magnetic surveys are useful for targeting the copper-gold porphyry deposits. The potassic alteration zone consists of the radiometric K element facilitating the application of the radiometric survey for targeting this zone. Nevertheless, the investigation depth of the radiometric approach is less than a few centimeters, and therefore, it is suitable only for mapping the deeply eroded deposits in which the mineralization occurred in the potassic alteration zone. Result The ground magnetic and IP-RS geophysical data of the Dalli Cu-Au porphyry deposit were interpreted based on the proposed conceptual model of the geophysical signature of Cu-Au porphyry systems. Integrating and evaluating the geophysical processes with the result of preliminary drillings indicated that in the Dalli Cu-Au porphyry deposit, the zones with positive and strong magnetic anomalies, high to moderate chargeability and high conductivity, are associated with copper and gold mineralization. Therefore, these criteria should be considered in designing the additional/infill boreholes in further exploration plans for this deposit. Discussion The magnetic, IP and RS surveys are the most important and common geophysical methods for targeting the porphyry copper and gold deposits. In particular, implementation and integration of these three methods can be more effective. Other geophysical approaches such as gravity, electromagnetic and seismic methods are also applicable for this purpose, but they are more expensive and complicated than the afore-mentioned approaches. For proper analysis of the geophysical data, first, it is necessary to recognize the geological model, hydrothermal alteration and mineralization systems of the studied deposits and the geophysical signatures of each alteration zone. Then, an appropriate interpretation of geophysical data is provided through combining the geological information of the deposit with the geophysical data. References Clark, D.A., 2014. Magnetic effects of hydrothermal alteration in porphyry copper and iron-oxide copper–gold systems: A review. Tectonophysics, 624–625 (1): 46–65. Cooke D.R., Hollings P., Wilkinson J.J. and Tosdal, R.M., 2014. Geochemistry of Porphyry Deposits. In: H.D. Holland and K.K. Turekian (Editors), Treatise on Geochemistry. Elsevier, USA, pp. 357–381. Dentith, M. and Mudge, S., 2014. Geophysics for the Mineral Exploration Geoscientist. Cambridge University Press, New York, 454 pp. Holden, E.J, Fu, S.C., Kovesi, P., Dentith, M., Bourne, B. and Hope, M., 2011. Automatic identification of responses from porphyry intrusive systems within magnetic data using image analysis. Journal of Applied Geophysics, 74(4): 255–262. Hoschke, T.G., 2011. Geophysical Signatures of Copper-gold Porphyry and Epithermal Gold Deposits, and Implications for Exploration. ARC Centre of Excellence in Ore Deposits, University of Tasmania, Tasmania, 47 pp. Sillitoe, R.H., 2010. Porphyry-copper systems. Economic Geology, 105(1): 3–41.