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Tourmaline is a borosilicate mineral with general formula of XY3Z6[T6O18](BO3)3V3W. Experimental studies demonstrate a wide range of stability for tourmaline-supergroup minerals to record different geological processes. They occur in metamorphic, granitic pegmatites, and clastic sedimentary rocks and are associated with hydrothermal activities (Dutrow and Henry, 2011; Slack and Trumbull, 2011). Textural and compositional features of tourmaline can be used as an indicator of environment in which it crystallized. Tourmaline from porphyry deposits generally show a. frequently crystal zoning, b. development from Fe-rich to Mg-rich, and c. total Mg content is ~2 apfu in copper deposits and 1-2 apfu in Au deposits (Baksheev et al., 2012). It is believed that the world-class Dashkasan gold deposit records the transformation of porphyry to low-sulfide epithermal (Richards et al., 2006). The Dashkasan gold deposit located in the Kurdistan Province can be a significant region for better understanding the origin and the evolution of ore-forming fluids using chemistry of tourmaline. For the present study, we also tried to apply fluid inclusions data on quartz-tourmaline-pyrite veins from the Dashkasan deposit.Materials and MethodsPolished-thin sections of various tourmalines of the Dashkasan deposit were examined using a Cameca SX100 Electron Probe Micro Analysis (EPMA) at the Iran Mineral Processing Research Center, Karaj. Fluid inclusion studies were performed on quartz crystals of quartz-tourmaline-pyrite veins. The microthermometric parametes of fluid inclsions were measured by Linkam-THMS-600 stage at the University of Isfahan.Results and DiscussionThe Dashkasan gold deposit with 52 Mt of oxidized ore and average grades of 1.77 g/t Au is hosted by the Middle-Miocene porphyritic dacite/rhyodacite and dacitic breccia rocks. The main minerals are quartz, K-feldspar, hornblende and biotite mainly altered.. This deposit is characterized by the transition from the porphyry to the epidermal system with the presence of tourmaline minerals in phyllic and silicification alteration associated with gold veins. As petrographic examination shows tourmaline occurs as disseminated, vein/veinlet, and breccia textures in three types: Tur-1 occurred as needle shape in dacitic rocks associated with phyllic alteration; Tur-2 crystallized as radial shape mainly coexisting with silicification; and Tur-3 with elongated shape is present in dacitic breccia with phyllic alteration.Mineral ChemistryThe geochemical composition of three types tourmalines points to the nature and the evolution of ore-forming fluids. Electron microprobe analyses of the studied tourmalines indicate that the Tur-1 and Tur-3 are dravite, and the Tur-2 is dravite to schorl in composition and they belong to alkaline group. The third type, unlike the other two, is characterized by poor zoning and higher values of Na, K, Fe, Mg and lower values of Ca. On Fetot-Ca-Mg ternary diagram, they plotted in the Ca-poor metapelites, metapsammites, and quartz-tourmaline rocks host. Magmatic genesis inferred from the higher Fe/(Fe+Mg) ratio for Tur-1 and Tur-2, while this ratio in the Tur-3 is different and shifted towards hydrothermal source.Microthermometric StudyRichards et al. (2006) present the fluid inclusion assemblages from quartz-tourmaline veins in sericitized wall rocks in the Dashkasan deposit consisting of hypersaline and rare vapor-rich inclusion. They have homogenization temperatures of 246° to 360 ℃, yielding salinities of 34.4 to 46.1 wt% NaCl equiv. (Richards et al., 2006). Fluids inclusions studies on quartz-tourmaline-pyrite veins related to transition between stage-1 and stage-2 of mineralization in the Dashkasan shows a salinity values from 15.9 to 16.8 wt% NaCl equiv. and homogenization temperature values between 185° to 254 °C.ConclusionsOn the basis of optical and scanning electron microscopy, three tourmaline types(Turs -1,-2 and -3) in the Dashkasan deposit, can be distinguished. Despite the lack of zoning in Tur-1 and Tur-2, the third type displays the poor zoning. The first-and the third-types of tourmalines are dravite (Mg-rich), whereas the second-type is dravite to schorl in composition. Magmatic genesis is reflected by higher Ʃ(Fe+Mg) and FeO/(MgO+FeO) ratios for the first two types. While these ratios in the Tur-3 is different and shifted toward hydrothermal source. To sum up, the occurrence of quartz-tourmaline-pyrite veins in the Dashkasan deposit is due to the existence of a fault system under the physicochemical performance of the ore-mineralized fluid by a sudden depressurization and probably gradual mixing with shallow water.AcknowledgmentsWe thank Dr. Gholizadeh and Dr. Shabanian for their assistance with experiments for EPMA. This study was financially supported by the University of Isfahan.

Iron and arsenic sulfides are considered as the most important gold hosts in the sediment-hosted disseminated invisible gold deposits. The Zarshuran gold deposit (155 tons Au with average grade of 2.63 g/t) is formed in the Lower Cambrian black shale and siltstone (Zarshuran unit) and Fe-rich carbonates (Chaldagh unit) host rocks. As-sulfide (e.g., realgar and orpiment) and arsenian pyrites are the most important host minerals of gold in this deposit. Based on EPMA data, pyrite with As content below the detection limit to 3.99 wt% occurs in six different types, respectively, Py0 (gold content of 0.01 ppm), Py1 (gold content of 0.02 ppm), Py2 (gold content of 0.03 ppm), Py3 (gold content of 0.02 ppm), Py4 (gold content of 0.04 ppm), and Py5 (gold content of 0.01 ppm). According to the evidences, gold can be present as participating in chemical bounded (Au+ and Au+3) or nanoparticle inclusions (Au0). The weak geochemical correlation (R2 = −0.6) between As and S elements in pyrites indicates that there is pyrite with a complex composition [Fe(S,As)2Au2S0], which As− has replaced S2−. Mineralogy and the abundance of Fe and S in the rock units suggest that gold mineralization in the Zarshuran deposit is well occurs in response to sulfidation process. Sulfidation occurs when H2S-rich ore-forming fluids react with Fe-bearing carbonate host rock to form pyrite, marcasite, and pyrrhotite minerals. Introduction Sediment-hosted disseminated gold deposits with high gold grade (> 1000 g/t) are known to contain gold as participating in chemical bounded (Au+ and Au+3) or nanoparticle inclusions (Au0)in the pyrite composition (Deditius et al., 2014). The Zarshuran gold deposit (155 t @ 2.63 g/t Au; Madan-Zamin Company, 2020) is situated 35 km north of Takab in the Takab-Angouran metallogenic district, NW Iran. According to Mehrabi et al. (1999) and Asadi et al. (2000), gold mineralization in the Zarshuran deposit is in many respects like the Carlin-style and Carlin-like gold deposits, respectively. Gold substitution has been reported to be below detection limit to a maximum of 0.64 wt.% and 3 wt.% in arsenian pyrite and arsenopyrite lattice, respectively (Voute et al., 2019). Here, we examine the relationship between geochemistry and textures of pyrite, with a view to constraining the mechanism of gold precipitation. We use electron probe microanalysis (EPMA) to study the composition of different pyrite types. The results show that distribution of ferrous iron (Fe2+) is controlled by the initial diagenesis of Fe-C-S systems. Materials and methods During field studies, mineralization outcrops and their associated host rocks were identified. After preparing thin and thin-polished sections, mineralogical studies were carried out by transmitted and reflected polarizing ZIESS Axioplan2 microscope. To identify and classify different pyrite types and investigate the possibility of presence of gold and trace minerals, eight thin-polished sections were prepared, and carbon coated. This study was carried out by scanning electron microscope (SEM) with EVO MA15 model in the Central Laboratory of Kharazmi University (Tehran, Iran). Then, to achieve the chemical composition of different types of pyrite, 104 points were examined by EPMA (model JEOL JXA-8530F) in the Laboratory of Geo Forschungs Zentrum (GFZ). Spot analysis was performed with a voltage of 20 kV, electron beam current of 10 nA, X-ray diameter of 2 μ and radiation time of 5 to 20 seconds. The standard examples used to calibrate the various elements in this experiment were as follows: FeS2 (for Fe and S), CoAsS (for As and Co), and free gold (for Au). The detection limits of the elements are Fe (300 ppm), As (200 ppm), S (300 ppm) and Au (200 ppm). To identify rare minerals such as mackinawite (Fe9S8), HR microscopic confocal Raman technique was used in the Central Laboratory of Shiraz University (Shiraz, Iran). The experiment was performed with an X50 laser, a wavelength of 785 nm with a power of 100 mw and a radiation time of 20s. Results and discussion Based on SEM and optical-microscopic studies, six types of pyrite have been identified in the Zarshuran deposit. They are (1) framboidal pyrite (Py0) (avg. = 30 μm in diameter), (2) fine-grained disseminated pyrite (Py1) (< 20 μm in diameter), (3) coarse-grained euhedral pyrite (Py2) (avg. = 100 μm in diameter), (4) porous/sponge pyrite (Py3) (avg. = 300 μm in diameter), (5) colloform pyrite (Py4) (avg. = 550 μm in diameter), (6) vein pyrites (Py5) (avg. = 55 μm in thickness). Decalcification and sulfidation of host rocks are two important mechanisms in genesis of sediment-hosted gold deposits, and the importance of sulfidation depends on the reactivity of Fe2+ and H2S rocks (Voute et al., 2019). The interaction of H2S-rich hydrothermal fluids with reactive iron originating from the host rocks (Cail and Cline, 2001) or through hydrothermal fluids added to the environment (Reich et al., 2005) which results in formation of Au(-As)-rich pyrite. Arsenic in pyrite can occur in various oxidation states that correspond to different crystallographic sites in the lattice and different substitution mechanisms. As− substitution for S2− is found in reducing conditions and often in sediment-hosted gold deposits; while As cations (As2+, As3+, As5+) replace Fe2+ under oxidation conditions (Reich et al., 2005; Deditius et al., 2014). The diagram of arsenic versus sulfur in the Zarshuran deposit shows that the concentration of As in the formed pyrites is strongly related to the decrease in concentration of S. Based on this, it can be concluded that As replaces S in the pyrite structure and in the form of As−..; Moreover, As species are common in pyrites of gold deposits with sedimentary host rocks. In the Zarshuran deposit the occurrence of gold in As-Hg-Sb sulfides in late drusy quartz veins (Daliran et al., 2018) is more important than the presence of gold in various pyrites. Finally, all evidence suggest that gold mineralization in the Zarshuran deposit occurs well in response to sulfidation process of Fe-bearing carbonate rocks. The correlation between gold content and degree of sulfidation in the Zarshuran deposit indicates that sulfidation process is a much more important mechanism to gold precipitation relative to addition of pyrite (pyritization).

Introduction The Himalayan-Tibetan and Zagros Mountain ranges which are the youngest and most extensive continental-collision orogens in Tethyan domain host many important sediment-hosted Pb-Zn deposits, including the world-class Jinding, Huoshaoyun, Mehdiabad, and Angouran deposits (Reynolds and Large, 2010; Rajabi et al., 2012; Rajabi et al., 2015; Hou and Zhang, 2015; Song et al., 2017). More than 300 sediment-hosted Pb-Zn deposits and occurrences have been identified in Iran (Rajabi et al., 2013). Cretaceous and Triassic carbonate successions are the most common host rocks for these deposits, which are largely distributed in both the Malayer-Esfahan metallogenic belt (MEMB) and the Yazd-Anarak metallogenic belt (YAMB) (Rajabi et al., 2012). The YAMB is located at the Yazd Block, northern margin of the Central Iranian Plate. Several Pb-Zn deposits and occurrences such as Mehdiabad, Nakhlak, Hovz-e-Sefid, Darreh-Zanjir, Mansurabad, Chah-Kharboze and Chah-­Mileh have been identified distinguished at YAMB. The Chah-­Mileh deposit is in 30 km northeast Anarak, 220 km northeast of Isfahan, YAMB. The Chah-­Mileh Pb-Zn district is located in the Anarak Metamorphic Complex (AMC). There are three Pb-Zn deposits that have been recognized at the Chah-­Mileh district, including Kuh-e Mileh, Mazra-e Deraz, and Seilacho. In this paper, we investigate geology, texture, mineralogy, alterations, fluid inclusions and genesis of the Chah-­Mileh Pb-Zn deposit. The present research study provides more insight into understanding of geology and mineralization conditions in the study area with an implication for future exploration. Materials and methods A total of 120 samples were collected from the host rocks and ore deposit. They were studied by a transmitted/reflected polarizing microscope, X-ray Diffraction (XRD) and Scanning Electron Microscope-Energy Dispersive X-ray analyzer (SEM-EDS). Thin sections were stained to differentiate calcite and dolomite according to the method of Dickson (1966). Fluid inclusion microthermometry was performed using a Linkam THMS600 heating-freezing stage (-190 °C to +600 °C) mounted on a ZEISS Axioplan2 microscope at the Kharazmi University (Tehran). Fluid salinity (wt.% NaCl eq.) and density (g/cm3) were calculated using the FLINCOR v.1.4 (Brown, 1989) and FLUIDS (Bakker, 2012). Results and discussion The Chah-­Mileh Pb-Zn is a stratabound and epigenetic deposit hosted in dolomitic marble of the Chah-Gorbeh Complex with Middle Triassic age. Mineralization is composed of sulfide minerals (e.g., galena, sphalerite, chalcopyrite and minor pyrite) and non-sulfide minerals (e.g., cerussite, mimetite, wulfenite, litharge, hemimorphite, smithsonite, malachite, hematite, goethite). The gangue minerals are mainly composed of quartz, dolomite, calcite, and barite. Silicification and dolomitization are the two main types of hydrothermal alterations. Three mineralization stages were recognized in the Chah-Mile deposit: 1) pre mineralization stage characterized by fine-grained disseminated pyrite, 2) main hydrothermal stage characterized by galena, sphalerite and chalcopyrite and 3) post-ore mineralization consisting of secondary sulfides and non-sulfide. Four types of fluid inclusions including two-phase liquid-rich (LV), two-phase vapor-rich (VL), monophase liquid (L), and monophase vapor (V) were observed in the dolomite, quartz and calcite. Microthermometric measurements show that ore minerals were precipitated from low-temperature (81 to 167 °C) and moderate salinity fluids (7.02-22.2 wt.% NaCl eq.). Basinal hydrothermal fluids were responsible for ore mineralization at the Chah-­Mileh deposit. Ore mineralization at the Chah-­Mileh deposit has been formed as a result of fluid mixing. The formation of large siliceous zones in an area is a sign of hydrothermal fluid rising to the surface and mixing and diluting with low-temperature meteoric waters. Considering all the geological evidence, mineralization style, orebody texture and structure, alterations and fluid inclusion microthermometry, it may be inferred that the Chah-­Mileh deposit is similar to the Mississippi Valley-type deposits.

Introduction The Saveh-Kashan-Qom copper belt, in the northern part of the Urumieh-Dokhtar Magmatic Arc (UDMA) consists of two of the oldest (gold and copper) zones in Iran (Samani, 1998; Rajabpour et al., 2017) where Upper Eocene-Oligocene Mard Abad-Bouin Zahra volcanic suite is situated. This volcanic suite hosts several copper deposits including Jarou, Gomosh Dasht, Ghezel Cheshme, Bidestan and Afshar Abad that are known as the "Kuh-e-Jarou Mining District". The Kuh-e-Jarou Mining District has a total potential ore reserve of 2 Mt Cu with an average grade of 3 wt.% (Zar-Azin Gostar Consultant Engineering Co., 2009). Upper Eocene volcanic and pyroclastic rocks of rhyodacite, trachyandesite, andesite, and trachytic tuff with high-K calc-alkaline to shoshonitic affinity consist of the main host rocks for Cu mineralization. These units are primarily intruded by post Eocene intrusive bodies. The geochemistry and genesis of ore bodies have not been fully understood since most previous studies in this area have been focused on petrology of volcanic and intrusive rocks. Moreover, the main purpose of this study is to investigate mineralization style, geometry, and textural-structural features of orebodies, alterations, and fluid inclusions with implication for genesis of Jarou, Gomosh Dasht, Ghezel Cheshme, Bidestan and Afshar Abad copper deposits. In addition, this research provides more insight into understanding geology and mineralization conditions in the study area with an implication for future exploration. Materials and methods Seventeen thin polished sections from the ores and the host rocks were prepared and they were studied by a transmitted/reflected polarizing microscope in the Iran Mineral Processing Research Center (Karaj, Iran). Five rock powdered samples were also analyzed using X-ray diffraction (XRD) spectrometry (X′ pert Philips) in order to identify the mineralogy of clay minerals in the mineralogy laboratory of Salamanca University (Spain). Fluid inclusion microthermometry was performed using a Linkam THMS600 heating-freezing stage (-190 to +600 °C) mounted on a ZEISS Axioplan2 microscope in the fluid inclusion laboratory of the Iranian Mineral Processing Research Center (Karaj, Iran). Salinities (wt.% NaCl eq.), density (g/cm3) and pressure (bars) were calculated using the FLINCOR v.1.4 (Brown, 1989) and FLUIDS (Bakker, 2012). Results and discussion The orebody is controlled by a series of feather-like ruptures and faults and its dominant mineral compositions are chalcopyrite and chalcocite with minor amounts of pyrite, galena, bornite and sphalerite. The gangue minerals are quartz, barite, calcite and chlorite. Four types of hydrothermal alterations including chloritization, sulfidization, silicification and epidotization were recognized. Based on field and petrographic studies, three mineralization stages were distinguished including (1) the pre-ore mineralization stage characterized by fine-grained disseminated pyrites, (2) the main hydrothermal stage consisting of three substages: I) an early quartz-chalcopyrite ± bornite vein, II) middle bornite-chalcocite ± covellite breccia ore, III) late galena and sphalerite inclusions, and (3) late-stage barite and calcite veins. Based on petrographic studies, five types of aqueous fluid inclusions have been distinguished in the quartz-chalcopyrite ± bornite and barite veins including two-phase liquid-rich (LV), two-phase vapor-rich (VL), liquid monophase (L), vapor monophase (V) and minor halite-bearing liquid-rich fluid inclusions (LVS). The results show that parental fluids with a density of >1 g/cm3 and an approximate depth of 400 meters were formed and they were followed by fluid inclusions with a density of

The NW-trending Urumieh-Dokhtar Magmatic Belt (UDMA) in the central-western Iran is a part of the Eastern Tethyan orogenic belt (Deng et al., 2018) and over past decades, it has become one of the most significant polymetallic (Au-Cu-Fe-Pb-Zn) provinces in Iran (Rabayrol et al., 2019; Ismayıl et al., 2021). While the Cenozoic magmatism and metallogeny of the UDMA are well known, its ore-forming potential during this period is still poorly understood (Alipour-Asll, 2019; Tale Fazel et al., 2019; Zamanian et al., 2020). Despite well-known Eocene to Miocene hydrothermal systems associated with extension-related and/or arc magmatism from the UDMA, the temporal and spatial association between continental-arc setting, Middle-Eocene magmatism and epithermal Au mineralization in the Buin-Zahra Range is not well understood.The Atash-Anbar polymetallic deposit (35°44′ N and 49°35′ E) is located ca. 70 km south of Qazvin city, central-northern Iran. A drilling program ~1000 m (including ten drill-holes) identified about 2 Mt of proven reserves grading at 2.13 g/t Au (locally up to 14 g/t) and 4.11% Pb + Zn + Cu (Pirooz, 2015).Herein, we focus on the textural, paragenetic relationships, and mineral chemistry of the Atash-Anbar polymetallic deposit. We focus on: (1) documenting the chemical composition of the different sulfides, (2) determining the chemical state of gold in iron sulfides, and (3) determining the sulfur activityMaterials and MethodsAbout 70 rock samples were collected from various parts of the deposit to determine the mineralogy, mineral textures, and mineral chemistry. The chemical composition of ore minerals was analyzed at the Analytical Center for multi-elemental and isotope research of SB RAS in Novosibirsk, Russia using a JEOL JXA-8100 electron microprobe (Japan) with five wavelength dispersive spectrometers and an energy dispersive spectrometer. Operating conditions were: 15-20 kV accelerating voltage, 30 nA beam current, and 20-30 s counting time. Sulfides and sulfosalts were analyzed for Fe, S, As, Cd, Sb, Te, Ag, Au, W, Zn, Pb, Bi, Hg, and Cu. The detection limits for major and minor elements are approximately 0.05 and 0.01 wt.%, respectively. Ten rock powdered samples were also analyzed using the X-ray diffraction (XRD) spectrometry (X′ pert Philips) in order to identify the mineralogy of clay minerals at the Iranian Mineral Processing Research Center (IMPRC), Karaj.Results and DiscussionAu-polymetallic veins in the Atash-Anbar deposit with an epigenetic nature and an approximate length of 5 to 80 meters and a maximum depth of 45 meters have been formed in the Middle Eocene andesite, dacite, and rhyodacite host rock (Eord unit). Mineralization with vein and veinlet, crustiform, colloform, breccia, and disseminated textures were occurred in three stages: pre-mineralization (disseminated pyrites), main mineralization (chalcopyrite vein (II-A), quartz-sulfide breccia veins (II-B) and barite-sulfide vein (II-C)), and post mineralization (late carbonate vein (III-A) and supergene (III-B)). Argillic alterations (kaolinite-illite±dickite mineral assemblage) together with silicification alteration (quartz± jasper assemblage) are the main alterations in the area. At Atash-Anbar deposit, gold is present both as native gold (Au0) and invisible solid-solution (Au+) in sphalerite and pyrite compositions. According to Co/Ni ratio (1.2 to 45), pre-mineralized disseminated pyrites have volcanic affinity and zoned pyrites have a hydrothermal origin. As the result of changes in Cd concentration (4657 ppm on average) and Zn/Cd ratio (18.68 on average) in the sphalerites, mineralization considered as high-medium temperature hydrothermal system (200 to 250 °C). Also, based on FeS mol% content of sphalerites (which varies from 0.11 to 0.4), the LogfS2 changes are between -10 and -14, which are consistent with the high to intermediate sulfidation deposit. Due to the paragenetic association of gold with pyrite and sphalerite ores, the absence of oxide minerals, the medium temperature of ore-forming fluid, near-neutral to acidic nature of pH (presence of argillic±sericitic alteration), and the high activity of sulfur show that the gold solubility and its transfer were conducted by Au(HS)2– bisulfide complex. Evidence suggests that the increased logfO2 is caused the decreased S2– activity and it has resulted in instability of bisulfide complex and gold deposition in quartz-sulfide breccia vein.

Introduction The Lakehsiah mining district is hosted in Early Cambrian volcano-sedimentary units (CVSU) of the Kashmar–Kerman zone, Central Iran. The Kashmar-Kerman belt is located between the Yazd block in the west and the Tabas block in the east and it is parallel to the Poshed badam, Tabas and Kalmard faults in the north and Koh Banan and Zarand faults in the south of the area (Ramezani and Tucker, 2003). Compositions of the volcanogenic rocks in this area vary from felsic to mafic and include rhyolitic, rhyodacitic tuff and spilitic lava and diabase. The sedimentary rocks include dolomites, dolomitic limestones and evaporites. Lakehsiah 1 deposit is one of three IOA outcrops in the Lakehsiah district which have been studied in this research. Materials and Methods The mineralogical study of alteration zones was carried out by light microscope with transmission light and X-ray diffraction (XRD) analysis, at the Mineralogical Laboratory of Bu-Ali Sina University and Iran Minerals Processing Research Center, respectively. Fluid inclusion and Raman spectroscopy studies were also performed to determine temperature, composition and evolution of the ore-forming fluid at the Institute of Earth Sciences SAS, Slovakia. Stable isotope geochemistry of quartz (O-H) was performed at the Cornell University, USA. Discussion Iron deposits hosted in the Tashk Group show hydrothermal alteration. The major minerals of the Sodic-Calcic alteration are the crystals of calcic amphiboles (tremolite-actinolite), pyroxene, calcite, magnetite and apatite. Propylitic alteration (chloritization and epidotization) is very widespread and affects volcanic and intrusive rocks. It consists of chlorite, epidote, calcite, and magnetite with minor amounts of sericite. Silicification alteration, occurs as distal alteration in both hanging wall and footwall host rocks, forming fine-grained to coarse grained quartz aggregates, veins and veinlets. Sericitic-argillic alteration occurs mainly in intrusions. Feldspar (plagioclase and K-feldspar) was altered to sericite and clay minerals. Minor quartz occurs as veinlets in this alteration zone. Na- Ca alteration in volcanic and intrusion rocks is exposed in the center of the area. Amphiboles mainly occur as replacements of plagioclase. Plagioclases were altered to chlorite, epidote, and calcite. Additionally, veinlets of quartz-epidote-chlorite, chlorite-epidote, epidote-quartz, quartz-calcite, calcite, chlorite-calcite, and epidote-calcite are observed. Quartz and carbonates (calcite) are widespread and veins of these minerals crosscut all the rocks described above. Lakehsiah 1 deposit, hosted within high-silica rhyolitic tuffs and domes, forms a steeply dipping tabular lens and it includes massive magnetite ± apatite ± quartz ± specular hematite ± Fe-Mg silicates. Fluid inclusion Petrography Four major types of fluid inclusions are observed based on proportions of vapor, liquid, and solid phases present at room temperature in quartz mineral. They are described as follows: 1-liquid-rich inclusions (L) 2-vapor-rich inclusions (V) 3-Two-phase liquid rich fluid inclusions (L+V) 4-three phase inclusions with halite solid phase as daughter mineral (L+V+H). Study of inclusions petrography shows that most of the inclusions present within this mineral are primary in origin, although secondary or pseudosecondary types have been identified. They have different sizes (typically 5–15 μm). Fluid inclusion shapes are rounded, elliptical, irregular, negative crystal shapes and square. Results Microthermometry and Raman spectroscopy Freezing and heating experiments were performed on Types 3 and 4 fluid inclusions. Stretching of inclusions was noted during heating of large fluid inclusions in quartz from mineralized quartz veins. In such samples, homogenization temperatures range from 217–428 °C for type 3 and 384-467°C for type 4. Micro-thermometric data were obtained from both Types 3 and 4 inclusions. The data obtained revealed variation in salinity of the trapped fluids. The final ice melting temperature in Types 3 and 4 inclusions varies from −4° to -18 and -9 to -19 °C with a mode at around -12 °C. Final ice-melting temperatures are lowest in the mineralized quartz veins. The first melting temperatures in multiphase Types 3–4 inclusions are also in a similar range which varies from -21 to -34°C. Based on their final ice melting temperatures, it varies between 10 to 27 and 40 to 44 wt. % NaCl equivalent for type 3 and 4 inclusions. T°C vs. salinity plots of inclusions show mixing of magmatic hot fluids with cold meteoric waters. Raman spectroscopy revealed presence of 69 mol % N2 and 31 mol % CO2 and 33 mol % N2 and 67 mol % CO2 in types 3 and 4 inclusions. These gases can be derived from mantle degassing (Wang et al., 2018) and chemical reactions during ascent of fluids. H-O isotopes Isotopic studies are among the most common methods for identifying the primary composition of ore-forming fluids in deposits (Barati and Gholipoor, 2014). In the study area, five quartz samples in quartz grains and veins were used for H-O isotope analyses, with the aim of determining the source(s) of ore-forming fluids. The δDH2O and δ18OH2O values of the ore-forming fluids in quartz samples vary from -60‰ to -80‰, and -4.71‰ to -1.42‰, respectively. The above observations reveal that the early ore-forming fluids are magmatic in origin and is characterized by high temperature and moderate to high salinity, and gradually evolve to low temperature, low salinity meteoric water. The Lakehsiah 1 Fe deposit is associated with the magmatism induced by the protracted subduction. The decrease in temperature, salinity and f(O2), as well as fluid-rock interactions, are the main factors controlling Fe deposition. References Barati, M. and Gholipoor, M., 2014. Study of REE behaviors, fluid inclusions, and O, S stable Isotopes in Zafar-abad iron skarn deposit, NW Divandarreh, Kordestan province. Journal of Economic Geology, 6(2): 235–‌275. (in Persian with English abstract) https://doi.org/10.22067/ECONG.V6I2.20257 Ramezani, J. and Tucker, R.D., 2003. The Saghand region, central Iran: U-Pb geochronology, petrogenesis and implications for Gondwana tectonics. American Journal of Science, 303(7): 622–665. https://doi.org/10.2475/ajs.303.7.622‏‏ Wang, Y., Wang, K. and Konare, Y., 2018. N2-rich fluid in the vein-type Yangjingou scheelite deposit, Yanbian, NE China. Scientific Reports, 8(1): 5662. https://doi.org/10.1038/s41598-018-22227-7

Introduction The Takab-Angouran ore field, one of the Iran’s largest gold districts, is located in northwestern Zagros and belongs to the northwestern part of the Sanandaj-Sirjan Zone. This area has a dominant NW-SE structural trend and is spatially associated with the Sanandaj-Sirjan zone. Its geological and petrological characteristics seem to have closer affinities to the Central Iran zone. There are no chronological data on the ultramafic rocks or associated amphibolites, granulites and calc-silicates of the Takab area and the petrogenesis of the ultramafic rocks and their tectonic relations with other parts of the metamorphic complex are unclear. A Neoproterozoic-Lower Cambrian age for the protoliths of Takab-Angouran ore field seems likely, in view of comparable lithology, stratigraphy and geochronology with the Central Iran zone. The Chaldaq gold prospect is located in the Takab-Angouran ore field, NW Iran, within Iman Khan NW-trending anticline. The rock units at the mining area mainly consist of Precambrian sequence (Iman Khan schist, Chaldaq limestone and Zarshuran black shale) overlain by Cambro-Ordovician limestone and Oligo-Miocene Qom Formations (Mehrabi et al., 1999). The gold mineralization in the Chaldaq prospect is hosted by Chaldaq carbonaceous sedimentary rocks. Two major sets of faults which were recognized by Mehrabi et al., 1999 at the Zarshuran mine are: 1) northwest (310–325) and 2) southwest (255–265). Herein, we report on the textural, paragenetic relationships, mineral chemistry and sulfur isotopes of the Chaldaq prospect. This study is focused on: (1) documenting the chemical composition of different sulfides, (2) determining the chemical state of gold in iron sulfides, (3) determining the sulfur activity, and (4) source of sulfur. Materials and methods About 70 rock samples were collected from various parts of the deposit for determinations of mineralogy, mineral texture, mineral chemistry and sulfur isotope. The polished thin sections were carbon coated and analyzed on a Camera SX100 electron microprobe at the Iranian Mineral Processing Research Center (IMPRC), Karaj. The detection limits for major and minor elements are approximately 0.05 and 0.01 wt.%, respectively. Sulfur isotope analyses were conducted on 0.05 g of a 200-mesh sized of pyrite and realgar which were handpicked and checked under a binocular microscope to ensure purity of >98%. Each sample was reacted with Cu2O powder to produce SO2. The SO2 gas was collected and purified, and followed by S isotopic analysis using a MAT252 mass spectrometer at stable isotope laboratory of the University of Arizona. The δ34S values were reported relative to Vienna Cañon Diablo Troilite (VCDT), and analytical precision is ±0.2‰. Results and discussion Based on field and petrographic observations, three mineralization stages including diagenetic, hydrothermal (early-ore, main-ore and late-ore substages), and supergene stages were identified at the Chaldaq deposit. At least six types of pyrite and arsenian pyrite were recognized at the Chaldaq deposit. On the basis of EPMA results, gold with 10 to 80 ppm Au content occurs as solid solution (Au+)in arsenian pyrite [(Fe2+As3+)S2Au2.S0]. Various studies have documented that gold in the primary ores of sediment-hosted gold deposits is largely hosted by arsenian pyrite, and that gold in occurs as a substituting cation in the form of solid solution (Au+) and/or as nanoparticles of native gold (Au0) (Cook and Chryssoulis, 1990; Fleet and Mumin, 1997; Reich et al., 2005). Au– and Au3+ have also been suggested to occur as solid solution in pyrite (Arehart et al., 1993; Li et al., 2003). The understanding of the chemical state of gold in iron sulfides is important for deep understanding of gold depositional mechanism in sediment-hosted gold deposits. Main-ore substage sulfide minerals has δ34S values ranging from 3.5 to 6.5 ‰ (avg. 5‰, n=6). The Fe content of sphalerites from the main-ore indicates that sphalerite precipitated from relatively low fS2 fluid. Based on all evidence, it can be said that sulfur mineralization of the Chaldaq prospect has been formed by the performance of oxidized hydrothermal fluid on organic-bearing carbonaceous host rocks (at the Chaldaq unit) and the systematic subtraction of H2S reductive species from that environment. Considering the low temperature (fS2 between -14 to -16) and the acidic to neutral pH (presence of kaolinite and illite) for the main-ore stage of hydrothermal mineralization in the Chaldaq prospect, probably the major contribution of sulfur is in the form of H2S. References Arehart, G.B., Chryssoulis S.L. and Kesler, S.E., 1993. Gold and arsenic in iron sulfides from sediment-hosted disseminated gold deposits: implications for depositional processes. Economic Geology, 88(3): 171–185. https://doi.org/10.2113/gsecongeo.88.1.171 Cook, N.J. and Chryssoulis S.L., 1990. Concentrations of invisible gold in the common sulfides. Canadian Mineralogist, 28(3): 1–16. https://doi.org/10.1007/s00126-0140562-z Fleet, M.E. and Mumin, A.H., 1997. Gold-bearing arsenian pyrite and marcasite and arsenopyrite from Carlin trend gold deposits to laboratory synthesis. American Mineralogist, 82(3): 182–193. https://doi.org/10.2138/am-1997-1-220 Li, J.L., Qi, F. and Xu, Q.S., 2003. A negatively charged species of gold in minerals–further study of chemically bound gold in arsenopyrite and arsenian pyrite. Neues Jahrbuch für Mineralogie-Abhandlungen, 5(2): 193–214. https://doi.org/10.1127/0028-3649/2003/2003-0193 Mehrabi, B., Yardley, B.W.D. and Cann, J.R., 1999. Sediment-hosted, disseminated gold mineralisation at Zarshuran, NW Iran. Mineralium Deposita, 34(3): 656–671. https://doi.org/10.1007/s001260050227 Reich, M., Kesler, S.E., Utsunomiya, S., Palenik, C.S., Chryssoulis, S.L. and Ewing, R.C., 2005. Solubility of gold in arsenian pyrite. Geochimica and Cosmochimica Acta, 69(6): 2781–2796. https://doi.org/10.1016/j.gca.2005.01.011

The Meshkin-Rasht Abad area is a small part of the western Alborz-Azarbaijan magmatic belt (AAMB). Field investigations reveal that andesitic-basalt rocks are the dominant rock units of the area with high-K calc-alkaline to shoshonitic affinities. On the basis of geochemical features all rocks are enriched in light rare earth elements (LREE), large ion lithophile elements (LILE) and have positive anomalies of Pb, U and Cs and Ti, Sr and Nb negative anomalies. These volcanic rocks have the criteria of active continental margin arcs on tectonomagmatic discrimination diagrams. Geochemical data, including low amounts of Cr, Ni, V, and Zr/Nb ratio suggest the enriched mantle source (lithospheric mantle) for the rocks under study. Moreover, the diagrams of the ratio of highly incompatible elements indicate the effect of slab-derived fluids on the magma generation. The Ce/Pb low value as well as various geochemical diagrams demonstrate that the magma is possibly contaminated by continental derived-crustal materials.

Introduction The Zarshuran gold deposit is located in the Takht-e-Soleyman complex, NW Iran. It is formed in the Iman Khan NW-trending anticline (Mehrabi et al., 1999; Samimi, 1992). The rock units at Zarshuran mainly consist of Precambrian sequence (Iman Khan schist, Chaldaq limestone and Zarshuran black shale) which are overlain by Cambro-Ordovician limestone and Oligo-Miocene formations. Gold mineralization in the Zarshuran area occurs associated with jasperoid alteration within the Zarshuran black shale and Chaldaq carbonate rocks (Bazdar et al., 2015). The deposition and transportation of mineralized fluids from buried igneous rocks, faulting and fractures in basement and covered units, physico-chemical exchange in site of deposition, and hydrothermal alterations are the most important controls on gold mineralization at Zarshuran. There is a structural control on mineralization and ore deposition with respect to the alignment of gold mineralization along the NW- and NE-trending faults at Zarshuran. The mechanism of deformation in the studied area has been controlled by two sets of main fault systems. The early system is the NW-trending steeply-dipping right-lateral strike-slip faults with a reverse component and the late systems are the NE-trending faults that have been displaced by the early system. In this study, the relationship between fractures and structural lineaments with gold mineralization in the Zarshuran gold deposit was studied by remote sensing methods and fractal analysis. Then, development of extension and compressive structures of the Imam Khananticline in the right-lateral shear zone and role of fractures related folding in mineralization were investigated. It revealed that the spatial distribution of the fractures systems in folding structures is related to the kinematic evolution and geometry of folding. Material and methods Relations between mineralization and fracture systems are interpreted using field observations, extraction of lineaments and fractal analysis in this study. The lineaments map of the study area were extracted using appropriate algorithms of spatial data (STA algorithm), using Landsat 8 satellite (ETM+ sensor) images by semi-automatic method. Also, fractal dimensions in six parts of the area were calculated for faults and structural lineaments using the square method, log-log charts and related fractal analysis. A total of 75 samples were collected from trenches and surface outcrops. Then, analysis was performed for measurement of base and precious metal assays by inductively coupled plasma-optical emission spectroscopy (ICP-OES) in the Kanpazhuh laboratory (Tehran, Iran). Geochemical anomalies were reported by field observations and geological maps, and the extension and compressive structures associated to right-lateral shear zones were studied after determining the areas with high fractures density. Then, the relations between mineralization and transverse and longitudinal fractures related to folding in the Iman Khan anticline are investigated and a schematic model of the ore formation related to the folded structure are presented. Results and discussion The study area is first divided into six parts (a to f) in order to calculate the fractal dimensions of the lineaments and faults. The most frequent trends of the lineaments and faults is at about N20E to N75E and N30E to N85E, respectively. In order to study the relation between fractal dimensions of faults and lineaments with the distribution of gold in study area, the fault and lineament maps are somehow combined with the gold distribution map. In parts of the study area where the fractal dimensions of faults and lineaments show high values, gold concentration is also high. This indicates a structural relationship between the density of lineaments and faults of the study area with distribution of gold mineralization. The most important fault structure affecting the study area is the Takab fault zone with NNW-SSE trend and a length of about 80 km. The Takab fault zone and its related fractures play a major role in transport of hydrothermal fluids, and the biometric data show that these activities have continued from Miocene to date (Mehrabi et al., 1999; Daliran, 2008). The right-lateral strike-slip movement of the Takab fault has led to displacement of the rock units in study area. Also, this right-lateral movements caused formation of fractures with different trends and compressive and extensional structures as folding, reverse faulting and normal fractures. The Iman Khan anticline hosting the Zarshuran gold deposit is one of the main structures related to the Takab fault movement. The fractures related to this folded structure have played an important role in transporting the hydrothermal fluids. The fracture systems related to the Iman Khan anticline, is generally of longitudinal and transverse type. Therefore, after the slab break-off event and formation of a compressive structure due to the strike-slip movement of the Takab fault, the faults served as pathways to the ore-forming fluids. All evidences shows that the longitudinal fractures have an important role in the mineralization along the Iman Khan anticline, although the thickness of the mineralized zone increases at the intersection of longitudinal and transverse fractures.

The Lakeh-Siah region is situated in the Central Iran Zone (CIZ), 40 km northeast of Bafq city in the Yazd province. The rocks of the study area belonging to the lower Cambrian; including rhyolite, andesite and pyroclastic surge with porphyry to glomeroporphyric textures. The intrusive igneous rocks occur as stock and dyke and have monzonitic and dioritic composition with intergranular and granular textures. Based on geochemical studies, the rocks under study are calc-alkaline, metaluminous to peraluminous nature. The study apatite shows LREE- enrichment relative to HREE, this is a remarkable feature of the Kiruna- type iron deposits. Also, the enrichment of LILE (such as Rb, Ba, La, U, K and Th) and depletion of HFSE (such as Nb, Ta, Zr and Y) in the host rock, is known as a characteristic of the magmatism in the subduction zones. Based on the concentration of rare and trace elements, the volcanic and to the magmatic arc setting. The overall evidences demonstrate that the primary intrusive rocks belong magma of the rocks have been generated from partial melting of oceanic crust, during the closure of the Proto-Tethys Ocean. Iron oxide- phosphorus magma derived from magmatic differentiation of primary mafic magmas and ascended to higher levels through faults and fractures. Oxygen and hydrogen isotopic study of quartz along with magnetite ore in this deposit and calculation the fluid equilibrium with it shows that the ore- bearing fluid has a magmatic origin.

The Baharieh copper deposit with an approximately tonnage 1 million tons of copper ore, is located in the Khorasan Razavi Province and 30 km of northeastern of the Kashmar. Based on subdivision structural geology of the Iran, the deposit is situated in the Sabzevar zone and Taknar complex. The mineralization as stratabound nature in an ore-horizon with an approximately length of 200 m and E-W trending occurs in middle Eocene andesitic to rhyolitic-tuff. Chalcopyrite and pyrite are the main sulfide minerals which accompanies with accessory minerals such as bornite, galena, sphalerite, covelline, chalcocite, malachite and hematite. Based on evidence of the electron probe micro analysis (EPMA) detected the maximum gold and silver contents 0.21 and 0.1 ppm in chalcopyrite, respectively and the maximum silver content is 0.14 ppm in galena. According to mineral chemistry studies, pyrite of the Baharieh deposit obtained the average ratio Co/Ni=2.71, which can be indicate its hydrothermal source. According to the results of the geo-thermometry of the Sb/Bi ratio in the galena and geochemistry of sphalerite (high concentration of Cd with an average value of 9220 ppm and low Zn/Cd=67.54) physico-chemical and thermodynamic conditions of the ore-bearing fluid in the Baharieh deposit has been concordant with average-temperature hydrothermal-magmatic deposits. The variation ranges of δ34S isotopic in the chalcopyrite and pyrite samples are varies between -7.3 to 0.5 ‰.

Introduction Fluorite ore deposits are classified into three main groups: (1) magmatic deposits, (2) structures related deposits, and (3) sedimentary deposits (Dill, 2010). More than 30 fluorite occurrences with approximately 1.35 million tons of reserves have been recognized in Iran (Miller, 2014). Bagher Abad and Darreh Badam fluorite ore deposits, located in the southeast of Delijan (Markazi province) occur between the central Iran structural zone from the north and the Sanandaj-Sirjan structural zone from the south. The geology of the area is dominated by folded and faulted structures of Jurassic carbonates and shales (Thiele et al., 1968). The main host rocks for fluorite mineralization in the studied area are the Lower-Upper Jurassic carbonates and shales of Shemshak and Badamu Formations. Materials and Methods In this study, 70 samples from the various rock types including fluorite veins, host rocks and related alterations were collected. 25 thin- and polished thin-sections were prepared and studied to explain the mineralogy and paragenetic sequence of the ore body. Eight double-polished sections were also prepared for micro-thermometric analysis. The micro-thermometric analyses were conducted on primary fluid inclusions using Linkam THM600 heating-freezing stage connected to a TMS94 temperature controller and a liquid nitrogen pump (LNP) cooling system. Results The main host rocks for fluorite mineralization in the studied area are composed of the lower Jurassic slate and phyllite (Shemshak Formation) and the Middle to Upper Jurassic dolomitic limestone and calcareous sandstone (Badamu Formation). The main alterations associated with fluorite mineralization are sericitization, silicification and argillization. According to the fluid inclusions data, fluorite mineralization in Bagher Abad and Darreh Badam deposits were precipitated because of pressure reduction of ore bearing fluids and mixing of a primary moderate-salinity brine with less saline meteoric water. Estimation of trapping pressure-temperature of the mineralizing fluid in Bagher Abad fluorite deposit using the intersecting CO2 and H2O isochors for aqueous, aqueous-carbonic and carbonic fluid inclusions indicated that fluorite mineralization occurred at 180-260°C and 1-2 kbar pressure. According to the present study, circulation and upward flow of hydrothermal fluids (containing H2O and CO2) that originated from underlying altered bedrock provided appropriate conditions for increasing the solubility of metals and formation of halide (Cl¯ and F¯) metal complexes. Reaction with wallrock and gradual decrease in temperature due to mixing and dilution of the above-mentioned fluids with low-salinity meteoric water resulted in fluorite mineralization in favorable structures such as veins. Discussion Bagher Abad and Darreh Badam fluorite ore deposits are examples of epigenetic mineralizations which are not related to igneous activities in Iran. The mineralization is formed in nearly vertical veins, which are relevant to local fractures hosted in the Lower-Upper Jurassic carbonates and shales with east-west trend. The main ore textures are open-space fillings, breccias, veins and cavities associated with sericitic, silicic and argillic alterations. Micro-thermometric measurements were carried out on primary fluid inclusions in fluorite, calcite and barite minerals from both Bagher Abad and Darreh Badam deposits. Three types of fluid inclusions were distinguished: (1) two phase aqueous fluid inclusions (LV), (2) liquid (L) or vapor (V) mono phase inclusions, and (3) aqueous-carbonic (L1+L2+V) fluid inclusions. The first ice melting temperatures (Te) of two phase aqueous inclusions (LV) in fluorite, calcite and barite from Bagher Abad and Darreh Badam deposits vary between -32 to -15°C and -35 to -24°C, respectively, which represents a H2O+NaCl±KCl multiphase fluid (Van den Kerkhof and Hein, 2001). The last ice melting temperatures (Tmice) vary between -10.5 to -2.3°C and -12.0 to -5.6°C which are equal to salinities of 5.6-14.7 and 8.3-15.2 wt% NaCl equivalent for Bagher Abad and Darreh Badam deposits, respectively. The final homogenization temperatures (Thtotal) vary between 127 to 188 °C and 176 to 270°C for Bagher Abad and Darreh Badam deposits, respectively. The CO2 melting temperatures (TmCO2) of aqueous-carbonic inclusions in fluorite, calcite and barite show a range of -58.3 to -56.6°C which suggests CH4 and/or N2 impurities (Burruss, 1981). The clathrate melting temperatures (Tmclath) ranging from -6.0 to +1.0°C represent salinities between 5.5 to 18.2 wt% NaCl equivalent for both Bagher Abad and Darreh Badam fluorite deposits. References Burruss, R.C., 1981. Analysis of phase equilibria in C–O–H–S fluid inclusions. In: L.S. Hollister and M.L. Crawford (Editors), Fluid inclusions: applications to petrology. Mineralogical Association of Canada Short Course Series, Ontario, pp. 39–74. Dill, H.G., 2010. The chessboard classification scheme of mineral deposits: mineralogy and geology from aluminum to zirconium. Earth-Science Reviews, 100(1): 1–420. Miller, M.M., 2014. Fluorspar. In: S.M. Kimball (Editor), Mineral commodity summaries 2014. U.S. Geological Survey, Reston, Virginia, pp. 56–57. Thiele, O., Alavi, M., Assefi, R., Hushmand-zadeh, A., Seyed-Emami, K. and Zahedi, M., 1968. Explanatory text of the Golpaygan quadrangle map, scale 1:250,000. Geological Survey of Iran, Geological quadrangle E7, Tehran, 24 pp. Van den Kerkhof, A.M. and Hein, U.F., 2001. Fluid inclusion petrography. Lithos, 55(1–4): 27–47.

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.

The Agh-Daragh study area in the north of Ahar is located in Ahar-Arasbaran zone. The area is distinguished by W, Cu and Au metal endowment and has been explored during stream sediment and heavy mineral exploration. At least, three mineral occurrences are detected in Agh-Daragh area including Cu stockwork-disseminated mineralization in Chupanlar (occurred in Omz quartz-monzonite), Cu-Au±W vein-type mineralization in Ayran Goli (occurred in Og granodiorite), and Fe±Cu skarn in Gowdal (occurred between quartz-monzonite unit and crystallized carbonate). Chemically, Agh-Daragh mineralization-related metaluminous granitoids belong to oxidized, I-type and high-K calc-alkaline to shoshonitic series. They have SiO2 = 63.5–67.6 wt%, Al2O3 = 14–16.5 wt%, and K2O/Na2O = 0.5–1.8. Moreover, LILE enrichment relative to HFSE depletion and HREE in the granitoids and the dikes occurred due to fluid-melt interaction, which are characteristics of subduction tectonic environment. In their magmatic evolution, the Agh-Daragh intrusive rocks underwent a transition from the early intrusive phases belonging to granodiorite (Og unit) with low K/Na and Fe2O3/FeO ratios and to the late intrusive phases belonging to quartz-monzonite (Omz unit) enriched in K (K/Na >1) and oxidized (Fe2O3/FeO >1). It seems that high content of volatiles in high-K and oxygenate magmas occurs due to saturation of magmatic melt in water under a lower degree of quartz-monzonite crystallization immediately preceding Cu-Au±W mineralization at Agh-Daragh intrusive suite. Combining our field geology and geochemical-metallogenic evidences, we conclude that the mineralization in Agh-Daragh area mostly occurred in accompany with late quartz-monzonite stocks; as a result, identification of high-K intrusive rocks and related dikes have important implications for proceeding exploration planning specially indicating of drilling points, and further refines the basis for mineral exploration in Sheyviar Dagh intrusive suite and subsequently in Ahar-Arasbaran metallogenic zone.

Introduction The Ahar-Arasbaran metallogenic area (Qara Dagh zone) is located in the northwest of Iran and the western part of the Mazandaran Sea. At the base of the structural classification from Nabavi (1976), this area is situated in the Alborz-Azerbijan magmatic belt. Sheviar Dagh (Ahar batholite) intrusive suite, subvolcanic and volcanic accompanied rocks with east-west trending and 30 km long serves as the main Eocene-Oligocene magmatic event in the north of the Ahar province. Considering geochemistry, this assemblage includes two shoshonitic and calc-alkaline to high-K calc-alkaline series which are the shoshonitic series in the central part and the calc-alkaline series outcrop in the western and eastern part (Aghazadeh, 2009). Textural characteristic, mineral chemistry and fluid inclusion studies were carried out at the tree part of the Agh-Daragh prospecting area. Material and methods A total of 50 samples were collected from the host rocks (including 4 trench and 250 m), ore deposit and altered rocks. Ten altered samples were analyzed for their mineral recognition by X-ray diffraction in the Iran Mineral Process and Research Center (IMPRC). Electron microprobe analyses (EMPA) and backscattered electron (BSE) images of minerals were obtained using a Cameca SX100 electron microprobe in 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. Typical spot sizes ranged from 2 to 5 μm. A total of 5 double-polish thin sections representative of quartz samples were selected from mineralized veins after petrographic and field studies. Fluid inclusion microthermometry was conducted using a Linkam THMS600 heating–freezing stage (-190°C to +600°C) mounted on a ZEISS Axioplan2 microscope in the fluid inclusion laboratory of the school of Earth Sciences of the Kharazmi University. The heating rate was 5–10 °C/min at higher temperatures (>100°C), with a reproducibility of ±1°C. However, it was reduced to 0.1–0.5°C/min near phase transformation, with a reproducibility of ±0.1°C. Results Mineralization that occurs in the area is mainly related to the Sheiviar Dagh intrusive rocks and it includes a variety of types of skarn, porphyry- and vein-type, epithermal and intrusion related deposits. Agh Daragh mineralization occurs at least in three states including: 1) stockwork-disseminated, 2) vein-type and 3) replacement (skarn). In order to determine the nature and characteristics of granodiorites hosted Ayran Goli mineralization, the biotites points were analyzed. The Ayran Goli granodiorite with calc-alkaline nature is related to orogenic zones that is associated with subduction zones. To determine the chemical properties of the minerals in Gowdal skarn mineralization, garnet and chlorite have been used for analysis which are often located at repidolite and picnochlorite positions. Electron micro probe analysis (EMPA) of magnetite from the Chupanlar area showed that it belongs to porphyry and Kiruna type deposits. Based on the observations made, three types of aqueous fluid inclusions were distinguished in the quartz-sulfide veins, including halite-saturated aqueous (H2O–NaCl±KCl), aqueous two-phase (H2O–NaCl±CaCl2), and monophase liquid and vapor fluid inclusions. Discussion Because of the lack of CO2-bearing fluid inclusions phase in the samples, we used a temperature-pressure relationship intersection in order to obtain the depth of mineralization. However, but at this study salt-rich inclusions (type 1) the dissolution of halite homogeneous solid phase (Bodnar, 1994) were used in order to estimate the standing deposit. Considering the temperature of the liquid-vapor homogenization (Thl-v), temperatures between 201 to 474°C, homogenization halite (TmNaCl) between 196 to 434°C (48 wt% NaCl eq.) in the solid phase inclusions with halite, minimum and the maximum pressure between 4.0 and 7.2, respectively that occur at 0.4 to 2.7 kb (average of 5.1 kb and 4 km depth) under lithostatic pressure. These conditions are consistent with the occurrence of gold porphyry copper deposits introduced by Hedenquist et al., (1998). The presence of gas-phase inclusions (type 3), gas-rich (type 2) and a solid-bearing phase, halite (type 1) in a mixture of fluid inclusions indicates the occurrence of fluid immiscibility (Bodnar, 1995; Fournier, 1999). In such circumstances, homogenization temperature inclusions are trapped as their temperature is taken. Petrographic evidence on the simultaneous presence of these two categories is stored as the initial fluid temperature up 400 to 500°C with boiling and fluid immiscibility. References Aghazadeh, M., 2009. Petrology and geochemistry of the Anzan-Khan Kandi and Sheivier Dagh granitoids (north and east of Ahar, East of Azerbijan). PhD thesis, Tarbiat Modares University, Tehran, Iran, 493 pp. (in Persian with English abstract) Bodnar, R.J., 1994. Synthetic fluid inclusions: XII: the system H2O–NaCl. Experimental determination of the halite liquidus and isochores for a 40 wt.% NaCl solution. Geochimica et Cosmochimica Acta, 58(3): 1053–1063. Bodnar, R.J., 1995. Revised equation and table for determining the freezing point depression of H2O-NaCl solutions. Geochimical et Cosmochimica Acta, 57(3): 683-684. Fournier, R.O., 1999. Hydrothermal processes related to movement of fluid from plastic to brittle rock in the magmatic-epithermal environment. Economic Geology, 94(8): 1193-1212. Hedenquist, J.W., Arribas, A. and Reynolds, T.J., 1998. Evolution of an intrusion-centered hydrothermal system: Far Southeast Lepanto porphyry and epithermal Cu-Au deposits, Philippines. Economic Geology, 93(4): 374-404. Nabavi, M.H., 1976. An introduction to the Iranian geology. Geological Survey of Iran, Tehran, 110 pp.

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

Introduction The Senj deposit has significant potential for different types of mineralization, particularly porphyry-like Cu deposits, associated with subduction-related Eocene–Oligocene calc-alkaline porphyritic volcano-plutonic rocks. The study of fluid inclusions in hydrothermal ore deposits aims to identify and characterize the pressure, temperature, volume and fluid composition, (PTX) conditions of fluids under which they were trapped (Heinrich et al., 1999; Ulrich and Heinrich, 2001; Redmond et al., 2004). Different characteristics of the deposit such as porphyrtic nature, alteration assemblage and the quartz-sulfide veins of the stockwork were poorly known. In this approach on the basis of alterations, vein cutting relationship and field distribution of fluid inclusions, the physical and chemical evolution of the hydrothermal system forming the porphyry Cu-Mo (±Au-Ag) deposit in Senj is reconstructed. Materials and Methods Over 1000 m of drill core was logged at a scale of 1:1000 by Pichab Kavosh Co. and samples containing various vein and alteration types from different depths were collected for laboratory analyses. A total of 14 samples collected from the altered and least altered igneous rocks in the Senj deposit were analyzed for their major oxide concentrations by X-ray fluorescence in the SGS Mineral Services (Toronto, Canada). The detection limit for major oxide analysis is 0.01%. Trace and rare earth elements (REE) were analyzed using inductively coupled plasma-mass spectrometery (ICP-MS), in the commercial laboratory of SGS Mineral Services. The analytical error for most elements is less than 2%. The detection limit for trace elements and REEs analysis is 0.01 to 0.1 ppm. Fluid inclusion microthermometry was conducted using a Linkam THMS600 heating–freezing stage (-190 °C to +600 °C) mounted on a ZEISS Axioplan2 microscope in the fluid inclusion laboratory of the Iranian Mineral Processing Research Center (Karaj, Iran). Results The Cu-Mo Senj deposit covering an area about 5 km2 is located in the central part of the Alborz Magmatic Arc (AMA). The Nb/Y versus Zr/TiO2 diagram (after Winchester and Floyd, 1977) illustrates a typical trend for the magmas in the Senj magmatic area–starting from basaltic and evolving to dacite/rhyodacitic compositions, with few data plotting in the alkali basalt field. Most of the igneous rocks plot within the medium- and high-K fields in the K2O versus SiO2 diagram. The igneous rocks from the Senj area define a typical high-K calc-alkaline on SiO2 versus K2O diagram (Le Maitre et al., 1989). 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 (Pearce and Can, 1973). At least three veining stages namely QBC, QM, and QP which are related to alteration and mineralization are distinguished at the Senj mineralized area. Three distinct alteration assemblages including K-feldspar-biotite-sericite-quartz, quartz-sericite-K-feldspar-pyrite, and K-feldspar-biotite-sericite-quartz, are distinguishable with these veins. About 80 % of the copper at Senj is associated with the early QBC-stage veins, with another 5 to 15 % in the QM-and QP-stage veins. About 70 % of the molybdenite occur in QM veins. Discussion Fluid inclusion distribution, fluid chemistry, and homogenization behavior document that S2-type fluids are samples of magma-derived aqueous-saline fluids characterized by high salinity and temperature, and high Cu content. Such parental fluids scavenged Cu and Mo from the melt below and transported them to the hydrothermal system above. The increased abundance of S- and LV-types inclusion coinciding with the highest grade Cu mineralization (early QBC-stage veins) at the Senj deposit suggests that brine-vapor unmixing and phase separation plays an important role in Cu-ore precipitation and alteration zonation. In addition to unmixing, cooling and water-rock interaction also played important roles in chalcopyrite precipitation at the Senj deposit. Compositions, deposit-scale distribution, and trapping conditions of fluid inclusions can be explained by the continued influx of a parental high salinity magmatic hydrothermal fluid, with no significant change in the bulk composition of the input fluid over the integrated lifetime of ore metal precipitation and vein formation. Fluid inclusion evidence and vein-cutting relationships indicate that molybdenum mineralization (QM vein) occurred at moderate temperatures coinciding with phyllic alteration, rather than from later, lower temperature fluids. Furthermore, early fluids decompressed rapidly relative to cooling, forming quartz-stockwork veins with K-silicate alteration at depth and QP veins at shallower levels in the Senj deposit. Later, as the hydrothermal system waned, the rate of decompression relative to fluid cooling slowed, causing the fluid to remain above its solvus, forming barren quartz-dominated veins with quartz-kaolinite±illite alteration which overprint much of the deposit. References Heinrich, C.A., Günther, D., Audétat, A., Ulrich, T. and Frischknecht, R., 1999. Metal fractionation between magmatic brine and vapor, determined by micro-analysis of fluid inclusions. Geology, 27(7): 755–758. Le Maitre, R.W., Bateman, P., Dudek, A., Keller, J., Lameyre, J., Le Bas, M.J., Sabine, P.A., Schmid, R., Sorensen, H., Streckeisen, A., Woolley, A.R. and Zanettin, B., 1989. A classification of igneous rocks and glossary of terms. Blackwell Scientific Publications, Oxford, 193 pp. Pearce, J.A. and Can, J.R., 1973. Tectonic setting of basic volcanic rocks determined using trace elements analysis. Earth and Planetary Science Letter, 19(2): 290-300. Redmond, P.B., Einaudi, M.T., Inan, E.E., Landtwing, M.R. and Heinrich, C.A., 2004. Copper deposition by fluid cooling in intrusion-centered systems: New insights from the Bingham porphyry ore deposit, Utah. Geology, 32(3): 217–220. Ulrich, T. and Heinrich, C.A., 2001. Geology and alteration geochemistry of the porphyry Cu– Au deposit at Bajo de la Alumbrera, Argentina. Economic Geology, 96(8): 1719–1742. Winchester, J.A. and Floyd, P.A., 1977. Geochemical discrimination of different magma series and their differentiation products using immobile elements. Chemical Geology, 20(5): 325-343.

Introduction More than 30 fluorite occurrences with approximately 1.35 million tons of reserves have been recognized in Iran (Ghorbani, 2013). The Atashkuh fluorite-barite (±sulfide) deposit is one of four occurrences located south of the city of Delijan in Markazi province, about 80 km SE of Arak city. The Atashkuh deposit occurs between the central Iran structural zone on the north and the Sanandaj-Sirjan structural zone on the south. The geology of the area is dominated by folded and faulted Jurassic carbonates and shales (Thiele et al., 1968). The lower Jurassic shale and calcareous sandstone of the Shemshak Formation and the Middle to Upper Jurassic dolomite of the Badamu Formation are the main host rocks for the fluorite veins. In this study, 40 samples from fluorite veins and host rocks were collected, from which 25 thin sections and 8 doubly-polished thin sections were prepared. Micro-thermometric studies were conducted on primary fluid inclusions using the Linkam THM600 heating-freezing stage. In addition, 10 samples were analyzed by XRD. Results Fluid inclusion data indicate that the Atashkuh fluorite-barite (±sulfides) veins were deposited as a result of mixing a primary multi-component Na-K(-Mg-Ca) high-salinity brine (SH type inclusions) with less saline calcium-rich connate water (LVHH type inclusions) and pressure reduction of ore bearing fluids. Fluid inclusions containing halite in high-salinity brine, and hydrohalite in connate water show suggest a high-salinity brine and connate water before mixing. The main mineralization stage was followed by circulation of low temperature meteoric water, responsible for the late stage mineralization. The micro-thermometry results suggest that the main fluorite mineralization occurred at 250 °C and 150 Mpa pressure. Dolomitization and silicification are the main alteration types associated with the Atashkuh mineralization. The occurrence of chlorite, talc, illite and dolomitized host rock all suggest Mg metasomatism associated with the main stage of fluorite mineralization. As a result of these observations, three stages of mineralization were recognized in the Atashkuh area: (1) Mobilization of a primary multicomponent Na-K(-Mg-Ca) high-salinity basinal fluid from the underlying rocks and its migration to the upper horizons. This stage is corresponds with the multi-phase SH inclusions with salinity of 31 wt% NaCl equivalent and 220 to 350 °C temperature. (2) Mixing and dilution of the basinal saline fluid with low-salinity formation or connate water resulted in deposition of fluorite-barite (±sulfide) mineralization and the formation of ferruginous dolomites. This stage contains Ca-Na rich inclusions with hydrohalite (LVHH). (3) Carbonate dissolution and increase in CO2 content of solutions due to oxidation of pyrite, formation of sulfuric acid. This stage is supergene oxidation and deposition of supergene minerals. The dissolution of carbonate rocks by acidified meteoric water produced permeable structures and breccias, by followed by of supergene mineralization in the later stages and formation of cerussite, malachite and goethite. Discussion The Atashkuh fluorite-barite (±sulfide) mineralization is mainly associated with dolomitized and silicified Jurassic carbonates and shales of Shemshak and Badamu Formation. The mineralization is in the form of two veins about 1 km apart. The epigenetic vein mineralization mainly consists of fluorite and barite with subordinate quartz, calcite, dolomite, galena, chalcopyrite, pyrite, hematite, goethite, malachite and cerussite. The main ore textures are replacements, open-space fillings, breccias and veins. The petrographic studies suggest three paragenetic suites: fluorite/quartz/calcite, barite/dolomite/sulfides and hematite/cerussite/goethite as early, middle and late stages. Micro-thermometric measurements were carried out on primary fluid inclusions of fluorite, barite and quartz crystals from both mineralized veins of the Atashkuh deposit. Fluid inclusions are of several types: (1) two-phase, liquid-vapor (LV), two- phase aqueous with hydrohalite (LVHH), multiphase (SH), H2O-CO2 with clathrate (C1) and without clathrate (C2) were recognized and analyzed. The first ice melting temperature (Te) of fluorite, barite and quartz two-phase aqueous (LV) inclusions varies between -22°C and -25°C, representing a H2O ± NaCl ± KCl multiphase solution (Van den Kerkhof and Hein, 2001). The last ice melting temperatures of three samples (Tmice) vary between -4.9°C to -9.7°C, -3.2°C to -7.2°C and -2°C to -4.8°C which indicate salinities of 7.7-13.6, 5.2-10.7 and 3.2-7.5 wt% NaCl equivalent for fluorite, barite and quartz. The final homogenization temperatures (Thtotal) of these inclusions vary between 90 and 205 °C for fluorite, 130 to 270 °C for barite and 110 to 193 °C for quartz. The CO2 melting temperatures (TmCO2) of fluorite and quartz C1 inclusions show ranges of -57.1 to -58.5 °C which suggest the presence of CH4 and/or N2 impurities (Burruss, 1981). The clathrate melting temperature (Tmclath) varies between 4.8 and 8.5 °C representing a salinity of 5.3 to 9.2 and 3 to 6.7 wt% NaCl equivalent for fluorite and quartz. The CO2 homogenization temperature (ThCO2) in these inclusions is 7.4 to 18.8 °C for fluorite and 13.4 to 27.5 °C for quartz. The homogenization temperature (Thtotal) for these inclusions is 170-210 °C for fluorite and 195-280 °C for quartz. References Burruss, R.C., 1981. Analysis of phase equilibria in C–O–H–S fluid inclusions. Mineralogical Association of Canada Short Course, 6(3): 39-74. Ghorbani, M., 2013. The economic geology of Iran, mineral deposits and natural resources. Springer Netherlands, 569 pp. Thiele, O., Alavi, M., Assefi, R., Hushmand-zadeh, A., Seyed-Emami, K. and Zahedi, M., 1968. Explanatory text of the Golpaygan quadrangle map, scale 1:250,000. Geological Survey of Iran. Geological quadrangle E7, 24 pp. Van den Kerkhof, A.M. and Hein, U.F., 2001. Fluid inclusion petrography. Lithos, 55(1-4): 27-47.

The base (Cu–Pb–Zn) and precious metals (Ag±Au) mineralization at the No. 4 anomaly of Golojeh deposit occurred in volcanic and sub–volcanic Eocene–Oligocene host rocks, in the central part of the Tarom–Hashtjin zone. Basic to intermediate volcanic, volcaniclastic and sub–volcanic rocks are dominated in the area and include andesite, basaltic andesite, trachy-andesite, dacite and tuff with affinity to sub–alkaline to high–potassic calc–alkaline series. The mineralization in the area with average grade of Au (0.15 ppm), Ag (0.24%), Cu (0.6%), Zn (4%) and Pb (6%) occurred in two major NW–SE trending quartz–sulfide veins (A and B) with crustiform, breccia, vein–veinlet and open-space filling structure and texture. The sulfide content varies from 5 to 60% and is dominated by galena, sphalerite, chalcopyrite and pyrite. SEM studies indicated presence of Ag (0.47 to 0.66 wt.%) and Cd (0.33 to 0.72 wt.%) in galena and Fe (0.23 wt.%) in sphalerite. Hydrothermal alteration of phyllic (quartz–sericite–pyrite), argillic (quartz–illite/muscovite) and silicification are related to mineralization. Correlation coefficient of metal pairs of Cd–Zn (0.86), Cd–Pb (0.82), Pb–Ag (0.80), Au–Ag (0.75), Pb–Zn (0.70) and Cd–Bi (0.74) was recorded in the quartz–sulfide ore–bearing veins. Microthermometric studies on two phases liquid–vapor fluid inclusions in ore–bearing veins, shows homogenization temperature to liquid (Thlv→l) in the range of 223 to 287°C and salinity of 6.5 to 17 wt.% NaCl eq. (quartz-hosted) and homogenization temperature ranging from 175 to 244°C and salinity from 1.5 to 12 wt.% NaCl eq. (sphaerite-hosted). First ice–melting temperature (Tmf) ranges of fluid inclusion in sphalerite-hosted of quartz–sulfide ore–bearing veins were recorded between −23 and −18°C in NaCl–H2O system. Vein–breccia and crustified structure and texture, presence of illite/muscovite alteration assemblage accompanied by high contents of galena, sphalerite and minor chalcopyrite and tennantite, low to moderate temperature and salinity of ore-bearing fluid, low depth of mineralization and Fe–bearing sphalerite features at the No. 4 anomaly of Golojeh deposit, are similar to those of intermediate sulfidation (IS) epithermal base and precious metals vein–type deposit that probably might be related to Cu–Au porphyry system in depth.

The Iranian East Magmatic Assemblage (IEMA) in the Central Lut region, hosted porphyry and vein-type polymetallic mineralization. The GaleChah-Shurab mining district is located in NW of the IEMA. Volcanic and subvolcanic bodies in the area are composed of calc-alkaline porphyry quartz-latite, porphyry dacite and rhyodacite and hornblende-biotite andesite, equivalent to I-type granite. They emplaced in Tertiary and intruded the Jurassic shale, siltstone and limestone basement (Shemshak Fm). The faults, joints and fractures, are the main controls on the mineralization, in forms of disseminated, vein, veinlet and minor stockwork and brecciation type mineralization of Pb, Zn, Cu, Sb and trace elements. Vein and veinlet of Pb+Zn±Cu±Sb in the Gale-Chah abandoned mine accompanied by carbonate and silicic alterations in association with galena, sphalerite, pyrite, chalcopyrite, bournonite and tetrahedrite as the hypogene ore minerals and their supergene products including cerussite, covellite, digenite and second-generation colloidal pyrite. The Pb+Zn+Cu+Sb mineralization associated with sericitic and silicic alterations in the Shurab abandoned mine, is composed of two types of mineralization, veinlet and brecciation vein in the porphyry dacite boundaries with Jurassic shale and sandstones, and the disseminated and disseminated-veinlet mineralization which is hosted by the altered porphyry dacite and rhyodacite intrusive rocks. The mineral assemblages are galena, sphalerite, stibnite, As-bearing pyrite, chalcopyrite and tetrahedrite-tennantite complex hypogene-sulfide ore as a hypogene ore, and malachite, covellite, cerussite and melancoitic pyrite as a sulfide-oxide supergene ore. The Pb+Zn+Sb±As±Ag polymetallic occurrence is associated with sericitic, carbonate and chloritic alteration assemblage in the Chupan occurrence, in two forms, I) vein, veinlet-stockwork (30m depth) confined to fault structures and II) disseminated-replacement (below 70m) mainly hosted in rhyodacite and porphyry dacite rocks. The hypogene minerals are galena, sphalerite, stibnite, pyrite, realgar-orpiment, arsenopyrite, and chalcopyrite with extensive occurrence of oxide-sulfide supergene products, such as Mn-oxide, hematite, malachite and colloidal pyrite. Fluid inclusion study show that disseminated veinlet Cu and disseminated-replacement polymetallic mineralization at the Shurab and Chupan deposits, respectively occurred in the high temperature, salinity and depth compared to vein-veinlet Pb and Zn mineralization of Gale-chah deposit. It seems that the mineralization is related to hydrothermal fluid evolution affected by mixing with cold and low salinity meteoric water.