Journal of Economic Geology

25-55

Authors: Malihe Golestani, Mohammad Hassan Karimpour, Azadeh Malekzadeh Shafaroudi and Mohammad Reza Haidarian Shahri

Introduction The Iju porphyry copper deposit is located in the southern part of the Urumieh-Dokhtar magmatic arc (Dehaj-Sarduieh belt) within the Kerman copper belt (Dimitrijevic, 1973). The Porphyry Copper mineralization in the Iranian plate occurs dominantly along the Urumieh-Dokhtar arc, which has resulted from the subduction of the Arabian plate beneath the central Iran and the closure of the Neo-Tethys Ocean during the Alpine orogeny (Hassanzadeh, 1993). The Iju porphyry copper deposit with 25 million tons of ore reserves is one of the main copper deposits within the Kerman copper belt. The mining area is composed of upper Miocene volcanic and subvolcanic rocks (mineralized and barren subvolcanic rocks) and quaternary deposits. Two hydrothermal alteration zones of quartz-sericite-pyrite and propylitic zones can be identified in the Iju area. The copper mineralization in the Iju deposit occurs as disseminated, stockwork and hydrothermal breccia. In the hypogene zone, the mineral paragenesis include chalcopyrite, pyrite, with minor occurrences of bornite and magnetite. This paper reports geological, mineralogical, fluid inclusion and S isotope data from the Iju deposit in order to investigate ore-bearing fluids’ characteristics and the mechanisms of ore deposition. Materials and methods Fifteen samples of syngenetic quartz+pyrite bearing veinlets within the quartz-sericite-pyrite zone were selected from different depths across the seven boreholes. Quartz was used for double-polished thin sections and pyrite was used for sulfur isotope analysis. Fluid inclusion studies were performed using the Linkam cooling and heating stage, the THMSG 600 model. The syngenetic pyrite with thermometry quartz sample was used for the sulfur isotope experiments. Stable isotope analysis was performed at the Hatch Stable Isotope Laboratory in the University of Ottawa, Canada. Results The fluid inclusions of the Iju deposit represent a wide range in the homogenization temperatures between 140 to 480°C and salinity between 0.18 to >52.99 wt.% NaCl equiv., which are most similar to the results of the other Iranian porphyry copper deposits. Being located in the quartz-sericite-pyrite alteration zone, the results of thermometry indicates that ore deposition in the Iju deposit has occurred via mixing of magmatic and surface fluids. Variations in salinity and paragenesis of the saline multiphase fluid inclusions and two-phase gas-rich fluid inclusions indicate the occurrence of boiling phenomenon in some samples of the Iju deposit. The amount of δ34S for pyrite has a limited range close to zero (average, 0.229‰) that shows a magmatic origin for sulfur. Considering the presence of subvolcanic rocks, the type and extension of alteration zones, the structure and texture of ore bodies, thermometry results of fluid inclusions and sulfur isotope values, the Iju deposit is similar to porphyry copper deposits. Discussion In the quartz-sericite-pyrite zone, three main groups of veinlets have been identified. The quartz+pyrite veinlets are more abundant than the other types and they were selected for fluid inclusions and stable isotope studies. Petrographic studies of fluid inclusions identifies two groups of fluids including: 1- fluid inclusions without the halite phase, including the types L+V, L+V+S1 and (L+V+S1+S2, that is secondary), 2- fluid inclusions with halite phase, including the types L+V+H, L+V+H+S1, L+V+H+S1+S2 and L+V+H+S1+An. Homogenization temperature and salinity for the fluid inclusions without halite phase are as follows: 140 to 380°C and 0.18 to 24 wt.% NaCl (Fig. 8A and C) and for the fluid inclusions with halite phase they range from 230 to 480°C and 30 to 52 wt.% NaCl (Fig. 9A, B and D), In addition, the pressure and depth for the fluid inclusions containing halite phase are 750 bar and 3500 m on the average. Fluid inclusions available at the quartz veinlets of porphyry copper deposits can be formed in a wide range of chemical composition and under different temperature and pressure conditions (Rusk and Reed, 2008). The wide range in fluid inclusions data of the Iju deposit can be justified by physicochemical changes in the fluid as it is boiling and mixing with the surface fluids. Cooling, fluids mixing, boiling and fluid-rock reaction play important roles in the settling of chalcopyrite from the hydrothermal fluid and the dilution of saline ore-bearing fluids can cause the formation of copper ores from the ore-bearing fluid (Ulrich et al., 2002). Pyrite δ34S value ranges from -0.86 to +1.27‰ (average, +0.22‰) and the δ34SH2S value of the syngenetic fluid with pyrite ranges from -0.23 to -2.36‰ (average, -1.17‰). The limited and near zero range that is observed about δ34S value of the sulfur minerals indicates the controlling role of magmatic processes in the mineralization events (Chen et al., 2009). Acknowledgments This article is related to Project No. 27124.3 dated 2015, 2, 7 at the Ferdowsi University of Mashhad. We are thankful to and appreciate the Research and Development center of National Iranian Cu Industries (Shahr-e-Babak, Meiduk), especially S.M. Mousavi, for the financial support of this project and the necessary proceedings. References Chen, Y.J., Piranjno, F., Li, N., Guo, D.Sh. and Lai, Y., 2009. Isotope systematica and fluid inclusion studies of the Qiyugou breccia pipe- hosted gold deposit, Qinling Orogen, Henan province, China: Implication for ore genesis. Ore Geology Reviews, 35(2): 245-261. Dimitrijevic, M.D., 1973. Geology of Kerman region. Geological Survey of Iran, Tehran, Report No. Yu/52, 334 pp. Hassanzadeh, J., 1993. Metallogenic and tectonomagmatic events in the SE sector of the Cenozoic active continental margin of central Iran (Shahr e Babak area, Keman Province). Ph.D. thesis, University of California, Los Angeles, America, 204 pp. Rusk, B.G. and Reed, M.H., 2008. Fluid inclusion evidence for magmatic-hydrothermal fluid evolution in the porphyry copper- molybdenum deposit at Butte, Montana. Economic Geology, 103(2): 307-334. Ulrich, T., Gunther, D. and Heinrich, C.A., 2002. The evolution of a porphyry Cu-Au deposit, based on LA-ICP-MS analysis of fluid inclusions: Bajo de la Alumbrera, Argentina. Economic Geology, 97(8): 1889-1920.

73-92

Authors: Houshang Pourkaseb, Alireza Zarasvandi, Madineh Saed and Ali Reza Davoudian Dehkordy

Introduction The formation of porphyry copper deposits is attributed to the shallow emplacement, and subsequent cooling of the hydrothermal system of porphyritic intrusive rocks (Titley and Bean, 1981). These deposits have usually been developed along the chain of subduction-related volcanic and calc-alkalin batholiths (Sillitoe, 2010). Nevertheless, it is now confirmed that porphyry copper systems can also form in collisional and post collisional settings (Zarasvandi et al., 2015b). Detailed studies on the geochemical features of ore-hosting porphyry Cu-Mo-Au intrusions indicate that they are generally adakitic, water and sulfur- riched, and oxidized (Wang et al., 2014). For example, high oxygen fugacity of magma has decisive role in transmission of copper and gold to the porphyry systems as revealed in (Wang et al., 2014). In this regard, the present work deals with the mineral chemistry of amphibole and plagioclase in the Dalli porphyry Cu-Au deposit. The data is used to achieve the physical and chemical conditions of magma and its impact on mineralization. Moreover, the results of previous studies on the hydrothermal system of the Dalli deposit such as Raman laser spectroscopy and fluid inclusion studies are included for determination of the evolution from magmatic to hydrothermal conditions. Materials and methods In order to correctly characterize the physical and chemical conditions affecting the trend of mineralization, 20 least altered and fractured samples of diorite and quartz-diorite intrusions were chosen from boreholes. Subsequently, 20 thin-polished sections were prepared in the Shahid Chamran University of Ahvaz. Finally, mineral chemistry of amphibole and plagioclase were determined using electron micro probe analyses (EMPA) in the central lab of the Leoben University. Results Amphibole that is one of the the main rock-forming minerals can form in a wide variety of igneous and metamorphic rocks. Accordingly, amphibole chemistry can be used as an indicator for characterizing the conditions involved during the evaluation of magma crystallization i.e., pressure, temperature, liquid water content and oxygen fugacity. Most recent studies on the porphyry copper intrusions in the Urumieh- Dokhtar magmatic arc by (Zarasvandi et al., 2015a), indicate that all of the mineralized porphyry systems (Dalli porphyry is included) consistently show high levels of La/Sm and Sm/Yb, with concave upward patterns in the rare earth elements’ spider diagrams. Importantly, such features indicate high crustal assimilation in a relatively thickened crust and provide insight into the contribution of hornblende during the development of mineralized porphyry systems in the Urumieh- Dokhtar belt. The results of this study indicate that amphiboles of Dalli intrusions belong to the calsic group and range in composition from magnesio- hornblende, to edenite, magnesiohastingsite, and tschermakite. (Ridolfi et al., 2010), indicating that the alumina content of amphibole could be used for geobarometry. The calculations of geobarometry for quartz diorite intrusions of Dalli indicate that they formed in the pressure range of 136 to 287 (MPa). Also, calculation of magmatic water content using amphibole geochemistry indicates that the water content of quartz diorite intrusions in the Dalli were between 4.6- 5.7 (wt. %). The results of plagioclase chemistry indicate that there is a little zoning in this mineral. Also, the plagioclase composition varies from Or0.01 to Ab 0.48, An 0.50, Or 0.018, Ab 0.62 and An 0.35. They mostly have Andesine and Labradorite compositions. Discussion Amphibole minerals of the Dalli intrusions are calcic type and exhibit geochemical signatures of subduction zones. Also, characterizing the source of ore-hosting intrusions with amphibole chemistry indicate that parental magma of Dalli intrusion were generated from mixing of mantle melts with crustal materials. It seems that in an ongoing process of closure of Neo-Tethys, during compression and crustal shortening favourable conditions were provided for mixing of mantle melts with crustal materials. The geothermobaromerty calculations using amphibole and plagioclase minerals indicate conditions of 777 - 850 oC and 1-4 Kbar, representing magmatic stage of Dalli intrusions. Also, amphibole minerals are characterized by Fetot/Fetot + Mg > 0.3 and AlIV > 0.7 which reveal the presence of primary oxidative magma in the Dalli porphyry Cu-Au deposit. Oxidative conditions seem to have prevailed during the onset of the hydrothermal stage of the Dalli porphyry deposit. This is because it has been confirmed by laser Raman spectroscopy analyses that the most primitive quartz veins in the potassic alteration of the Dalli deposit are characterized by the presence of anhydrite and hematite minerals (see Zarasvandi et al., 2015b). Also, microthermometry results on the most primitive barren quartz veins in potassic alteration represent temperatures as high as 620oC which indicate the beginning temperature of hydrothermal conditions. Acknowledgements Many thanks are due to the office of vice-chancellor of the Shahid Chamran University of Ahvaz for valuable information concerning the field work and sampling. References Ridolfi, F., Renzulli, A. and Puerini, M., 2010. Stability and chemical equilibrium of amphibole in calc-alkaline magmas: An overview, new thermobarometric formulations and application to subduction-related volcanoes. Contributions to Mineralogy and Petrology, 160(1): 45–66. Sillitoe, R.H., 2010. Porphyry Copper Systems. Economic Geology, 105(1): 3-41. Titley, S.R. and Beane, R.E., 1981. Porphyry copper deposits. Part 1. Geologic Setting, Petrology, and Tectogenesis. In: J.W. Hedenquist, J.F.H. Thompson, R.J. Goldfarb and J.P. Richards (Editors), Economic Geologists, 75th Anniversary Volume. Society of Economic Geologists, U.S.A, pp. 214-234. Wang, R., Richards, J.P., Hou, Z.Q., Yang, Z.M., Gou, Z.B. and DuFrane, A., 2014. Increasing Magmatic Oxidation State from Paleocene to Miocene in the Eastern Gangdese Belt, Tibet: Implication for Collision-Related Porphyry Cu-Mo ±Au Mineralization. Economic Geology, 109(7): 1943–1965. Zarasvandi, A., Rezaei, M., Sadeghi, M., Lentz, D., Adelpour, M. and Pourkaseb, H., 2015a. Rare earth element signatures of economic and sub-economic porphyry copper systems in Urumieh–Dokhtar Magmatic Arc (UDMA), Iran. Ore Geology Reviews, 70: 407-423. Zarasvandi, A., Rezaei, M., Raith, J., Lentz, D., Azimzadeh, A.M. and Pourkaseb, H., 2015b. Geochemistry and fluid characteristics of the Dalli porphyry Cu–Au deposit, Central Iran. Journal of Asian Earth Sciences, 111: 175-191.

117-136

Authors: Samaneh Nadermezerji, Mohammad Hassan Karimpour and Azadeh Malekzadeh Shafaroudi

Introduction The Shah Soltan Ali area is located 85 km southwest of Birjand in the South Khorasan province. This area is part of the Tertiary volcanic-plutonic rocks in the east of the Lut block. The Lut block is bounded to the east by the Nehbandan and associated faults, to the north by the Doruneh and related faults (Sabzevar zone), to the south by the Makran arc and Bazman volcanic complex and to the west by the Nayband Fault. The Lut block is the main metallogenic province in the east of Iran (Karimpour et al., 2012), that comprises of numerous porphyry Cu and Cu–Au deposits, low and high sulfidation epithermal Au deposits, iron oxide deposits, base-metal deposits and Cu–Pb–Zn vein-type deposits. The geology of Shah Soltan Ali area is dominated by volcanic rocks, comprised of andesite and basalt, which are intruded by subvolanic units such as monzonite porphyry, monzodiorite porphyry and diorite porphyry. Materials and methods 1. 170 thin sections of the rock samples as well as 25 polished and thin polished sections were prepared for petrography, alteration and mineralization. 2. Twenty five samples were analyzed for Cu, Pb, Zn, Sb, Mo and As elements by the Aqua regia method in the Zarazama laboratory in Tehran, Iran. 3. Nine samples were analyzed for trace elements [including rare earth elements (REEs)]. As a result of these analyses, trace elements and REE were determined by inductively coupled plasma mass spectrometry (ICP-MS) in the ACME Analytical Laboratories (Vancouver) Ltd., Canada. 4. Ten samples were analyzed for major elements by wavelength dispersive X-ray fluorescence spectrometry in the East Amethyst laboratory in Mashhad, Iran. 5. Five samples were analyzed for Firre Assay analysis in the Zarazma Laboratory in Tehran, Iran. 6. The results of XRD analysis were used for 4 samples. Discussion and results Petrographic studies indicate that subvolcanic rocks consist of diorite porphyry, monzonite porphyry and monzodiorite porphyry. Based on field and lab work several alteration zones such as: quartz–sericite–pyrite (QSP), propylitic, argillic, silicified, sericitic and carbonate were identified. Geochemical studies show that intrusive units are metaluminous, high calcalkalic to shoshonitic. These rocks belong to the I-type granitoid (Chappell and White, 2001), and they have formed in a volcanic arc granitoids (VAG) tectonic setting (Pearce et al., 1984). Mantle-normalized, trace-element spider diagrams display enrichment in large ion lithophile elements, such as Rb, Sr, K, and Cs, and depletion in high field strength elements, e.g., Nb, Ti, Zr. Enrichment of LREE versus HREE and enrichment of LILE and depletion in HFSE indicate magma formed in the subduction zone. Negative Nb and Ti anomalies are recognized as a fingerprint of a subduction process (Nagudi et al., 2003). All of the intrusive rocks have a weak negative Eu anomaly (Eu/Eu*=0.82–0.94) (Tepper et al., 1993), and a low ratio of (La/Yb)N. The magmatic source of intrusive rocks had been generated from 1% to 5% of partial melting of garnet-spinel lherzolite (Aldanmaz et al., 2000). In the south area, four types of mineralization such as: veinlet to vein, disseminated, hydrothermal breccia and stockwork occur from which stockwork is the most important type of mineralization. The veinlets that were found within the stockwork zone are:1) pyrite + chalcopyrite, 2) quartz + pyrite ± chalcopyrite, 3) quartz ± pyrite. Compositional variations of elements within the Shah Soltan Ali area are as follows: Cu = 30-454 (ppm), Zn = 27-279 (ppm), Pb = 11- 70 (ppm), Sb = 0.9-152 (ppm), Au= 5-128 (ppb), As = 7-203 (ppm). There is a high concentration of Cu – Zn – Au and Sb that is associated with the high density of veinlets in the quartz-sericite-pyrite zone in the southeast of Shah Soltan Ali area. Based on the obtained data, the Shah Soltan Ali area is a part of the porphyry Cu-Au deposit. References Aldanmaz, E., Pearce, J.A., Thirlwall, M.F. and Mitchell, J.G., 2000. Petrogenetic evolution of late Cenozoic, post-collision volcanism in western Anatolia, Turkey. Journal of Volcanology and Geothermal Research, 102(1): 67–95. Chappell, B.W. and White, A.J.R., 2001. Two contrasting granite types, 25years later. Australian Journal of Earth Sdiences, 48(4): 489-500. Karimpour, M.H., Malekzadeh shafaroudi, A., Farmer, G.L. and Stern, C.R., 2012. Petrogenesis of Granitoids, U-Pb zircon geochronology, Sr-Nd Petrogenesis of granitoids, U-Pb zircon geochronology, Sr-Nd isotopic characteristics, and important occurrence of Tertiary mineralization within the Lut block, eastern Iran. Journal of Economic Geology, 4(1): 1-28. (in Persian with English abstract) Nagudi, N., Koberl, Ch. and Kurat, G., 2003. Petrography and Geochemistry of the sigo granite, Uganda and implications for origin, Journal of African earth Sciences, 36(1): 1-14. Pearce, J.A., Harris, N.B.W. and Tindle, A.G., 1984. Trace element discrimination diagrams for thetectonic interpretation of granitic rocks. Journal of Petrology, 25(4): 956-983. Tepper, J.H., Nelson, B.K., Bergantz, G.W. and Irving, A.J., 1993. Petrology of the Chilliwack batholith, North Cascades, Washington: generation of calc-alkalinegranitoids by melting of mafic lower crust with variable water fugacity. Contributions to Mineralogy and Petrology, 113(3): 333-351.

159-174

Authors: Houshang Pourkaseb, Alireza Zarasvandi, Zahra Fereydouni, Babak Mokhtari and Neda Mirzaei

Introduction It has been recently stated that phosphorite deposits are in fact marine biogenic materials, due to bacterial activity producing bio-apatite. In addition, Phosphorites contain 15–20 wt.% P2O5 (Tzifas et al., 2014). In this deposit, phosphate mineralization has occurred as phosphorite lenses with Eocene age within the Pabdeh Formation, with thickness up to 1.5 meters and width of 15 meters and its hosted rock is black shale. According to the presence of indices of fossils such as Globorotalia, Hantkenina, its age can be attributed to the middle Eocene. The Pabdeh formation is a very rich organic matter in addition to the presence of phosphate (Damiri, 2011). The formation due to planktonic foraminifera rich in organic matter is like the hydrocarbon source rock (Daneshian et al., 2012). In marine basins where upwelling and productivity are limited, phosphates may develop outside of microbial cells and also within bacterial cellular structures, formed by slow bacterial assimilation of phosphorus from assaying organic matter in areas of restricted sedimentation (O’Brine et al., 1981). It is therefore suggested that the upwelling currents did that in the recycling of phosphorus from dead organisms such as fishes and other marine vertebrates. The aim of this study is investigation of organic matter’s species and their roles in deposition and phosphate mineralization in the Kuh-e-Sefid phosphate deposit using XRD, FTIR and Rock-Eval pyrolysis. Materials and methods In field observations, 12 samples were selected and they were taken from units of phosphate and shale host rock in the Kuh-e-Sefid phosphate ore deposit. Ten cross sections were studied by conventional microscopic methods. Rock-Eval analysis was used in order to determine the organic carbon in the geology Department of the Shahid Chamran University of Ahvaz. The Phosphorite samples were determined by XRD at the Kansaran Binaloud Company in the Science and Technology campus in Tehran. FTIR analyses were carried out on the phosphorite samples in the chemistry department of the Shahid Chamran University of Ahvaz. Results Organic matter appears to be essential for phosphogenesis in two ways: 1) as an energy supply for redox change and 2) as a source of phosphate. Similarly, bacteria are important on two levels: 1) they provide a mechanism for the release of phosphorus from phospholipids and other high-energy phosphorus compounds by organic phosphate cracking and organic carbon oxidation, 2) they are capable of concentrating and precipitating phosphate (Jarvis, 1992).The sedimentary organic matter is first decomposed exclusively by aerobic bacteria. When O2 is completely utilized, further decomposition occurs via sulfate reduction until the oxidants are exhausted, then phosphorus and carbon are released from organic matter during decomposition (Ingall and Cappellen, 1990). Field observation and microscopic studies indicate that phosphate-bearing layers mainly consist of shale, marl, limestone with textures varying from wackestone to packestone forms. Also, phosphate components such as plettal, ooid, intraclast, fish skeletal fragments and microfossils are present. In additions to phosphate and biogenic component, nonphosphate minerals such as glauconite, calcite, pyrite, iron oxide and quartz, are present in different forms and sizes. The results of XRD analysis show the mineral phosphate (fluorapatite) besides calcite as one of the nonphosphate components in the Kuh-e-Sefid ore deposit as the main constituents, while the minerals montmorillonite and quartz are minor constituents. FTIR studies reveal qualitative information about the bonding pattern and nature of the components of the organic matters. Thus, phosphogenesis in marine phosphate deposits resulting in the destruction of areas around the continents that contain different components of phosphate and non-phosphate, and the resulting destruction of organic materials as well. Therefore, according to data from the Rock Evil, samples of the deposit represent more continental carbon. In general, it can be shown that, most of the phosphate mineralization in this deposit is mainly of a continental origin, and it is partly as a result of decomposition and oxidation of organic matter by bacteria and microorganisms that occurs. Discussion - Since shales rich in organic matter are capable of transferring sedimentary phosphorus as organic materials, it can be concluded that the deposits shale as the phosphate deposits host were the main factors of phosphorus transmission and the most mineralization occurs in parts that are rich in organic matter. - Rock-Eval results showed that more samples contain continental carbon and this suggests that phosphate mineralization is of continental origin in this deposit and it is partly achieved by biodegradation of organic matter by microorganisms. - FTIR, XRD studies have proved the frequency of fluorapatite minerals with calcite and organic materials that are most probably associated with phosphate mineralization in the deposit. - FTIR studies reveal mineral-organic bounds such as OH, Carboxylic OH, Carboxylic acid C=O, C≡C Alkaline, group CH2, C=C aromatic, CH Aliphatic and aromatic stretching associated with identified mineralization. Acknowledgements Many thanks are due to the office of vice-chancellor of Chamran University of Ahvaz for valuable information concerning the field work and sampling. References Damiri, K., 2011. Geology, Geochemistry and Genesis of the Phosphate Ocurences in the Pabdeh Formation, southwestern Iran. M.Sc. Thesis, Shahid chamran University, Ahvaz, Iran, 146 pp. (in Persian with English abstract) Daneshian, J., Norouzi, N., Baghbani, D. and Aghanabati, A., 2012. Biostratigraphy of Oligocene and lower Miocene sediments (Pabdeh, Asmari, Gachsaran and Mishan formations) on the basis of Foraminifera in Southwest Jahrum, interior Fars. Scientific Quarterly Journal, Geosciences, 21)83(:157-166. (in Persian with English abstract) Ingall, E.D. and Cappellen, P.V., 1990. Relation between sedimentation rate and burial of organic phosphorus and organic carbon in marine sediments. Geochimica et Cosmochimica Acta, 54(2): 373-386. Jarvis, I., 1992. Sedimentology, geochemistry and origin of phosphate chalks. The upper cretaceous deposits of NW Europe. Sedimentology, 39(1):55-97. O’Brine, G.W., Harris, J.R., Milnes, A.R. and Veeh, H.H., 1981.Bacterial origin of East Australian continental margin phosphorites. Nature, 294: 442-444. Tzifas, I.Tr., Goldelitsas, A., Magganas, A., Anderoulakaki, E., Eleftheriond, G., Mertzimckis, T.J. and Perraki, M., 2014. Uranium-bearing phosphatized limestone of new Greece. Journal of Geochemical Exploration, 143: 62-37.

197-211

Authors: Behrouz Karimi Shahraki and Behzad Mehrabi

Introduction The Poshtebadam Bafq Zarand district in central Iran is a world class iron oxide province. This region contains over two billion tons of iron ore reserves within more than 34 major magnetic anomalies and deposits in an area of 7,500 km2 (Stosch et al., 2011). The Jalal-Abad iron ore deposit (200Mt at 45% Fe, 1.18% S and 0.08% P) is located 38 km northwest of Zarand, 16 km southeast of the Rizu town in the Kerman province, Iran. Iron ore deposits are hosted by the Early Cambrian Rizu Series, composed mainly of sedimentary, volcanic and volcaniclastic rocks which are dominated by dolomite, sandstone, shale, siltstone, tuff, ignimbrite and rhyodacite. The origin of the iron oxide deposits is controversial and various genetic models have been suggested. Some researchers believe in magmatic origins or Kiruna type, while others suggest metasomatic replacement from pre-existing rocks (Stosch et al., 2011). LA-ICP-MS has been used to characterize the multi element chemistry of the diverse fluid inclusions found in the Jalal–Abad iron oxide deposit. The aim of this investigation was to understand the genesis of the ore body and identify possible hydrothermal fluid sources in the Jalal-Abad district. Sampling and method of study About 100 samples from different types of ore were collected from surface outcrops and a drill core whose association with mineralization are well established. Thin sections, polished thin sections and polished sections were prepared. SEM studies (FEI 5900LV) and LA-ICP-MS analyses of fluid inclusions were carried out in the School of Earth and Environment, the University of Leeds, UK. Fluid inclusions were studied using a Linkam THM-600 heating-freezing stage mounted on Zeiss petrography microscope at the Iranian Mineral Processing Research Center. Result and discussion Jalal Abad deposit is hosted by the early Cambrian volcano-sedimentary rocks of the Rizu series. Stratabound mineralization occurs in a variety of forms being massive, disseminated, replacement, open space filling, veins and breccias. Immediate host rocks include sandy siltstone, acidic volcanic rocks and dolomite. The Jalal Abad deposit mainly consists of iron oxides (magnetite, hematite and goethite), pyrite, chalcopyrite, and malachite that occur in massive, brecciated, open space filling, disseminated and vein forms. Hematite mostly occurs close to the surface and along fractured zones, formed as a secondary mineral due to magnetite oxidation and it is rare at depth. Pyrite is the most important sulphide mineral and is associated with magnetite, calcite, quartz, talc, dolomite, actinolite and chlorite. Copper mineralization at shallow levels is mainly in oxides formed from sulphide oxidation and at deeper levels primary chalcopyrite is also associated with magnetite. Cu mineralization is formed as disseminated or in veins form. Native gold was detected as inclusions smaller than 50 µm in chalcopyrite. Common alteration minerals are goethite, pyrite, talc, actinolite, chlorite, tremolite, dolomite, quartz, calcite, albite and sericite. The earliest hydrothermal alteration includes Na-Ca alteration which is associated with actinolite, magnetite and pyrite. Multiphase fluid inclusions (L+V+S) in quartz are abundant and homogenization temperatures are in the range of 260 to 440◦C. Salinities vary between 30 to 52 wt% NaCl equivalents. The concentrations of Na and K are in the range 26906 to 140716 ppm and 2372 to 70484 ppm, respectively. Fe content varies from 576 to16076 ppm with an average of 6914 ppm and Cu contents vary from 51 to 3204 ppm with a mean of 792 ppm. The Na/Ca values for fluid inclusions vary from 0.38 to 37.51 with a mean of 3.79. The average content of Na is 61511 ppm which is in agreement with salinity of fluid inclusions measured by microthermometry techniques. Magmatic fluids normally yield K > Ca, with Ca/K ratios between 0.01 to 1, whereas non magmatic fluids are often richer in Ca with Ca/K between 1 to 100 (Yardley, 2005). The amounts of Fe and Cu in magmatic fluids are commonly above 10000 and 1000 ppm, respectively. However, it depends on chlorinity (Fisher and Kendrick, 2008; Gillen, 2010; Appold and Wenz, 2011). Mn concentrations are 424 to 3645 ppm, with an average concentration of 7581 ppm. Mn/Fe ratio is varied from 0.21 to 1.87 with an average of 0.60.The wide range of homogenization temperature (170 -450 °C) and salinity (31- 52 wt % NaCl equiv) of the fluid inclusions and ratios of K/Ca in fluid inclusions indicate different fluid sources with magmatic and basinal type fluids (Yardley, 2005). Mn/Fe ratios in fluid inclusions are in wide ranges (0.21 -1.87) which indicate the presence of both reduced type and oxidized type fluids (Fisher and Kendrick, 2008). Results In addition to iron oxide, economical Cu mineralization occurs in the Jalal Abad deposit with Au, Bi and As mineralzation with insignificant apatite. The K, Fe, Ca, Na and Cu concentrations in fluid inclusions are most probably related to the mixing of magmatic and basinal fluids. The mineralogical, microthermometry and chemistry of fluid inclusions data show that magmatic-hydrothermal metal bearing fluids, nonmagmatic hydrothermal fluids and mixing of them are responsible for iron-Cu-Au mineralization (IOCG) in the Jalal- Abad deposit. References Appold, M.S. and Wenz, Z.J., 2011. Composition of Ore Fluid Inclusions from the Viburnum Trend, Southeast Missouri District, United States: Implications for Transport and Precipitation Mechanisms. Economic Geology, 106(1): 55-78. Fisher, L.A. and Kendrick, M.A., 2008. Metamorphic fluid origins in the Osborne Fe oxide–Cu–Au deposit, Australia: Evidence from noble gases and halogens. Mineralium Deposita, 43(5): 483–497. Gillen, D., 2010. A study of IOCG-related hydrothermal fluid in the Wernecke Mountains, Yukon Territory, Canada. Ph.D. thesis, James Cook University, Queensland, Australia, 562 pp. S Stosch, H.G., Romer, R.L. and Daliran, F., 2011. Uranium–lead ages of apatite from iron oxide ores of the Bafq District, East-Central Iran. Mineralium Deposita, 46(1): 9–21. Yardley, B.W.D., 2005. 100th Anniversary Special Paper: metal concentrations in crustal fluids and their relationship to ore formation. Economic Geology, 100(4): 613–632.

235-248

Authors: Mehrdad Barati, Ebrahim Tale Fazel, Afshin Akbarpour, Babak Talaei and Masoud Moslehi

Introduction The Qahr-abad fluorite deposit is located in the area of 36°10′ 3′′ N and 46°34′ 21′′E within the Sanandaj-Sirjan district east of the Kurdistan province , Iran and it is located ~57 km southeast of the city of Saqqez (Kholghi Khasraghi, 1999). This deposit is developed as scatter lenses, veins, and veinlets (stockwork structure) within carbonate rocks of Elika formation and controlled by the regional NW–SE trending Zagross thrust nappe system. Fault trends in this area are perpendicular to fault trends in the Zagros zone. The fault dips are nearly vertical and mineralization has occurred in the brecciation fault zone (Talaii, 2010). The rough geological instruction of the deposit has indicated that it is similar to worldwide Epithermal deposits. The mineralization occurs as replacement (type I)/ open-space (type II) vein fillings and bodies within Mesozoic lime stones (mostly Upper Triassic and Lower Jurassic members of the Elika Formation), where they crop out to form horst structures. The mineralization is typically associated with post Pliocene disjunctive faults, which in part appear to have served as channel ways for the fluorite forming fluids that are representative of the geological setting of the mineralized area. Fluorite occurs in several color variations such as green, violet, blue, white or colorless, and is accompanied by quartz, barite and calcite (Moslehi, 2013). Materials and methods The minerals sampled for the fluid inclusion study include fluorite from mineralization stages. Samples covered all ore types. Micro thermometry analyses for 23 samples were performed after careful microscopic observation of 35 sections and 30 doubly polished sections. Micro thermometry was undertaken using a Linkam THS600 heating-freezing stage, with a measurable temperature range of between −196 and +600 °C (precision of freezing data and homogenization temperature of ±0.2 °C). Micro thermometry was undertaken in the Department of geology of the Karazmy University. Results Petrography and classification of inclusions: The samples used for the inclusion study were doubly polished sections of fluorite from mineralization stages 1 to 2. A number of inclusion types were identified. These include negative crystals and elongate round, polygonal or irregular shapes with a size range from <1 µm to several tens of µm. Based on their petrographic characteristics at room temperature and phase change characteristics during the heating process, inclusions were grouped into three principal types. Here we just discuss primary and pseudo secondary fluid inclusions, mainly including three fluid inclusions as follows: 1) (vapor + liquid) or (L+V) and negative crystal fluid inclusions, each of which will provide more believable information for the mineralization hydrothermal fluid. These fluid inclusions in fluorite are, isolated, and irregular or rectangular with 10 μm to 20μm long major axes. They include two phases at room temperature, an aqueous liquid (L) and some kind of carbonic vapor phase (V), and have L/ (V +L) Fillinge ratio values of 90–95%. Abundant fluid inclusions are present. 2) fluorite that are generally quadrilateral in shape, have 2–20 μm long major axes, and occur as clusters or form trails. These fluid inclusions contain three phases at room temperature depending on the density of the nonaqueous gases in the fluid inclusions and have nonaqueous phase ratios of around 5%. They have major axes 2–15 μm long. They contain two phases and have L/ (V + L) volume ratio values around 0.95%. 3) Fluid inclusions in some fluorite are rare. Most of them are isolated and roughly circular. They have 2–10 μm long major axes, and contain four phases as (liquid+ vapor + daughter mineral 1+ daughter mineral 2) or (L+V+S1+S2) and have L/(V + L) volume ratios of 90–92% at room temperature. Some twin fluid inclusions were also identified in this type and analyzed during this study. Discussion Thermometric investigations indicate that homogenization temperatures for primary and pseudo secondary fluid inclusions in all fluorite types range from 155 to 245°C with an average of 187°C. Gas phase changes to liquid phase in the homogenization processes. The degree of fillings in most inclusions are more than 90%. -23 to -18 °C with an average of -20.7°C. There are eutectic temperatures in the freezing method and calculated salinity is 30.8 wt% NaCl equivalents in terms of the H2O-CO2-NaCl system. The Bernoulli Effect has occurred in this resource (Barnes, 1998). Isothermal mixing, boiling, surface fluid dilution and depressurization are four processes that have effects on the mineralization in this resource (Wilkinson, 2001). Finally we think, Qahr -abad fluorite deposit has been prepared by hydrothermal to epithermal processes and fluids have basin origin (fossil waters) (Tajoddyn, et al, 2010) and the orebody has precipitated from this fluid, when it was mixed with cold surface waters. References Barnes, H.L., 1998. Geochemistry of hydrothermal ore deposits. John Wiley & Sons, Malaysia, 972 pp. Kholghi Khasraghi, M.H., 1999. Geological map of Irankhah. Scale 1:100,000. Geological Survey of Iran. Moslehi, M., 2013. The study of fluid inclusion and geochemistry of Qahr-Abad Soliman deposit in Kurdistan province. M.Sc. Thesis, Bu-Ali Sina University, Hamedan, Iran, 142 pp. (in Persian with English abstract) Tajoddyn, H., Rastad, A., Yaghobpour, A. and Mohajel, M., 2010. The genesis of Barica Gold massive sulfide deposit, east of Sardasht, NW of metamorphic Sanandaj –Sirjan zone base on structure, texture and micro thermometric studies. Journal of Economic Geology, 2(1): 97-118. (in Persian) Talaii, B., 2010. The study of mineralogy and geochemistry of Qahr-Abad fluorite deposit, SE of Sagez city, Kurdistan province. M.Sc. Thesis, University of Uromieh, Uromieh, Iran, 119 pp. (in Persian with English abstract) Wilkinson, J.J., 2001. Fluid inclusions in hydrothermal ore deposits. Lithos, 55(1-4):229–272.