Economic Geology
Leila Amini; Mohammad Maanijou
Abstract
One of the common processes that lead to the formation and enrichment of precious metal deposits is boiling. The existence of a spatial relation between fluid boiling and deposition of precious metals is a valuable tool in exploration of epithermal deposits. Therefore, the investigating of the process ...
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One of the common processes that lead to the formation and enrichment of precious metal deposits is boiling. The existence of a spatial relation between fluid boiling and deposition of precious metals is a valuable tool in exploration of epithermal deposits. Therefore, the investigating of the process occurrence in epithermal deposits will be able to predict the continuation of exploration trend. Chah-Morad epithermal gold deposit is located in 75 km northwest of Bazman in the Sistan and Baluchistan Province and in the Makran-Chagai Magmatic Arc southeast of Iran. The mineralization in the Chah-Morad deposit occurred in 3 stages and in quartz veins that exist between the altered argillic alteration zone and dacite and rhyodacite sub-volcanic rocks. Textural mineralogical and fluid inclusions studies indicate the occurrence of the boiling process in this deposit. The most important kinds of evidence for the occurrence of this process are: a) the presence of adularia, b) platy calcite texture, c) breccia, crustiform-colloform textures, d) different liquid-vapor ratios of fluid inclusions, e) the increase in the salinity of fluid inclusions with the decrease in homogenization temperatures, f) the coexistence of fluid inclusions with different salinities and g) co-existing liquid single-phase fluid inclusions with vapor single-phase fluid inclusions. Therefore, the existance of boiling is confirmed in the Chah-Morad deposit.
Economic Geology
Shayan Akrami; Mohammad Ali Aliabadi; Mohammad Reza Hazareh; Abbas Askari; Tayebeh Ramezani
Abstract
Nineh Pb-Zn deposit is located in the east of the Markazi province, in the Middle to Upper Jurassic rock units of the Malayer-Esfahan metallogenic belt. Stratified and epigenetic mineralization, in the form of veins, replacement and open spaces filling, including the main minerals of galena, sphalerite ...
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Nineh Pb-Zn deposit is located in the east of the Markazi province, in the Middle to Upper Jurassic rock units of the Malayer-Esfahan metallogenic belt. Stratified and epigenetic mineralization, in the form of veins, replacement and open spaces filling, including the main minerals of galena, sphalerite and barite accompanied by dolomite and siliceous alterations are observed. The microthermometry results of fluid inclusions in calcite and barite, display mean homogenization temperature of about 168.6°C and 127.3°C, and a mean salinity of 5.7 and 13.9 wt. % NaCl equiv., respectively, which indicates slight difference in their formation conditions. The homogenization temperature versus salinity diagram suggests a basinal brine fluid mineralizer and mixing and cooling processes for the mineralization. The values of δ34S in galena and sphalerite (7.5‰ to 21.5‰) of this deposit are similar to the values of δ34S in the upper Mississippi deposits, indicating the supply of sulfur during the process of thermochemical reduction of sulfate. The values of δ18OSMOW (-9.2 to -11.2‰) and δ13CPDB (0.1 to 0.5‰) of the calcite veins indicate a multi-origin of oxygen, and the origin of carbon from dissolved and remobilized marine carbonates. According to the evidence obtained during this study, the Nineh deposit can be classified as the Mississippi Valley type deposits, which was formed during the orogeny processes and the movement of basinal brine fluids.
Economic Geology
Hossein Ali Tajeddin; Ebrahim Rastad; Abdolmajid Yaghoubpour; Mohammad Mohajjel
Abstract
The Mirgenaghshineh gold deposit is located 43 km northwest of Saqqez in the northwestern part of the Sanandaj–Sirjan zone. The rocks in the deposit area predominantly consist of Precambrian volcanosedimentary sequences of schist, metasandstone, slate and metaandesite which are intruded by granitoid ...
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The Mirgenaghshineh gold deposit is located 43 km northwest of Saqqez in the northwestern part of the Sanandaj–Sirjan zone. The rocks in the deposit area predominantly consist of Precambrian volcanosedimentary sequences of schist, metasandstone, slate and metaandesite which are intruded by granitoid bodies. The Gold mineralization in the Mirgenaghshineh deposit is hosted mostly in Northwest-Southeast shear zone. The high grade gold ores occure in highly deformed mylonitic and ultramylonitic rocks that are associated with quartz, sericite-muscovite and sulfide alteration minerals. Ore mineral assemblages of the deposit are simple and consist of pyrite, arsenopyrite, sphalerite, chalcopyrite, galena and electrum. The electrum grains range in size from less than 5 µm to 140 µm and occur in quartz and also in the form of inclusion and veinlet in pyrites. According of geochemical data, gold-bearing ores carry up to 64.3 ppm Au, 9.9 ppm Ag, 2096 ppm As, 506 ppm Pb, 354 ppm Zn, and 244 ppm Cu. Fluid inclusion studies on gold-bearing quartz indicate homogenization temperatures between 158 and 215°C and salinity between 3.3 to 14.5 wt% NaCl eq. for the ore fluid. The study indicates that main characteristics of the geology and mineralization of the Mirgenaghshineh are similar to those of the epizonal orogenic gold deposits.
Economic Geology
Nima Rahimi; Shojaeddin Niroomand; Mohammad Lotfi; Mojtaba Rahimi Shahid
Abstract
The Janja Cu-Mo porphyry deposit is located at 70 km south of the Nehbandan, Sistan suture zone, Eastern Iran. The porphyry mineralization in the Janja deposit is temporally and spatially associated with the diorite to quartz diorite and granodiorite granular to porphyry stocks that intruded in the Cretaceous ...
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The Janja Cu-Mo porphyry deposit is located at 70 km south of the Nehbandan, Sistan suture zone, Eastern Iran. The porphyry mineralization in the Janja deposit is temporally and spatially associated with the diorite to quartz diorite and granodiorite granular to porphyry stocks that intruded in the Cretaceous flysch units. The Janja intrusions are represented by a Calc-alkaline and metaluminous geochemical affinity, and belong to the I-type granitoid series and subduction-related magmas in composition. Hydrothermal alterations in the area have been completely influenced by the Janja intrusion and as a result of the activity of these hydrothermal fluids, various types of potassic, propylitic, argillic and rarely phyllic alteration zones have been formed. In this deposit, three mineralization styles have been recognized including disseminated, vein-veinlet and stockwork which mineralization is mainly associated with potassic alteration. Mineralization zones in porphyry systems, including the supergene, enriched and hypogene zone, have been identified in the Janja deposit, which are the result of changes in the water table, weathering and erosion effects. The main sulfide minerals consist of chalcopyrite, pyrite, covellite, chalcocite, molybdenite, bornite, and oxide minerals including magnetite, hematite, goethite and hydro carbonate minerals including malachite and azurite. Fluid inclusion studies showed a homogenization temperature range from 301 to 540 ˚C and a mean salinity of 19 wt%NaCl for two-phase inclusions and a homogenization temperature range between 254 and >550 ˚C and mean salinities of 54 wt % NaCl for multiphase fluid inclusions. The results of these studies show that mixing processes have taken place in the Janja deposit and have caused the deposition of Cu-Mo-(Au) mineralization. Eventually, according to the various characteristics of the Janja deposit, including tectonic environment, host rock, mineralogy, ore-forming fluid, metal ore assemblage, mineralization and alteration patterns, and comparison of these characteristics with other porphyry deposits, it can be concluded that mineralization in Janja deposit is comparable with continental margin-type porphyry Cu-Mo-(Au) deposits.
Economic Geology
Monireh Sakhdari; Mehrdad Behzadi; Mohammad Yazdi; Nematollah Rashidnejad-Omran; Morteza Sadeghi Naeini
Abstract
The Godar Sorkh area is located in the central part of the Sanandaj-Sirjan zone, 20 km southwest of the Muteh region. Gold mineralization at Godar Sorkh occurs in quartz-sulfide veins that hosted in metasedimentary rocks. Veins of mineralization typically formed along normal faults. Rock sequences ...
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The Godar Sorkh area is located in the central part of the Sanandaj-Sirjan zone, 20 km southwest of the Muteh region. Gold mineralization at Godar Sorkh occurs in quartz-sulfide veins that hosted in metasedimentary rocks. Veins of mineralization typically formed along normal faults. Rock sequences are affected by several deformation phase, gold mineralization occurs in ductile to ductile-brittle shear zones and had been under poly-phase metamorphism. The main alterations are Sulfidation, carbonization, silicification, chloritization, and sericitization. Ore-mineral assemblages include pyrite and chalcopyrite, arsenopyrite, sphalerite, galena, and Fe-oxide. Mean homogenization temperature in gold-bearing quartz range between 275oC and 300oC. Fluid inclusions in quartz veins are dominated by CO2-H2O-NaCl fluid. Salinity ranges from 9 to 17 wt. % NaCl equivalent. Corresponding to a depth of <2 km, Godar Sorkh deposit is formed in epizonal environment. Measured δ18O values for the gold-bearing quartz range between 12.7 to 14.3 permil, estimated δ18Ofluid values range from +6.4 to +7.3 permil, δ34S values range from –16 to +5 permil, and estimated δ34Sfluid values range from +4.2 to -17.3 permil. Fluid inclusion and stable isotope studies on ore-bearing quartz-sulfide veins indicating the major role of metamorphic fluids. Gold derived from metasedimentary rocks. Gold mineralization in the Godar sorkh deposit classified as an orogenic gold deposit.
Economic Geology
Hadi Mohammadian; vartan simmonds; kamal Siahcheshm
Abstract
The Sarikhanloo area is located within the Qaradagh metallogenic zone in northwest Meshgin Shahr. Igneous rocks cropped out in this area include successions of Paleocene-Eocene pyroclastic rocks (tuff and andesitic-dacitic lavas with intercalations of ignimbrite) and basaltic andesite lava flows. Igneous ...
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The Sarikhanloo area is located within the Qaradagh metallogenic zone in northwest Meshgin Shahr. Igneous rocks cropped out in this area include successions of Paleocene-Eocene pyroclastic rocks (tuff and andesitic-dacitic lavas with intercalations of ignimbrite) and basaltic andesite lava flows. Igneous rocks show high-K calc-alkaline to shoshonitic nature and are mainly metaluminous, formed in a post-collisional uplift tectonic setting. Hydrothermal activities in this area brought about formation of vast silicic veins and caps, along with silicic, propylitic, phyllic (non-pervasive) and intermediate argillic alterations around the veins, as well as intermediate to advanced argillic alteration halos at the margins of silicic caps. Ore minerals in the silicic veins includes pyrite, arsenopyrite and Fe-oxides, accompanied by minor malachite, formed during four mineralization stages. Fluid inclusion studies indicate that the homogenization temperature of fluid inclusions ranges from 175 to 355 °C, considering the low pressure of fluid inclusions (≤ 0-40 bars), can signify the fluid temperature at the time of entrapment. The estimated salinity values are between 0.2 and 3 wt% NaCleq.
Economic Geology
Mehrdad Movahedi; Mohammad Yazdi; Mehrdad Behzadi
Abstract
The Oshvad skarn type deposit was formed during the intrusion of a felsic mass into the Permian and Triassic carbonate rocks and ion exchange occurred between the intrusion mass and these units. In order to determine the properties of the mineralizing fluid in this skarn, several fluid inclusions in ...
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The Oshvad skarn type deposit was formed during the intrusion of a felsic mass into the Permian and Triassic carbonate rocks and ion exchange occurred between the intrusion mass and these units. In order to determine the properties of the mineralizing fluid in this skarn, several fluid inclusions in quartz and calcite minerals of the mineralization zone were analyzed. The results show that these minerals have two types of fluids inclusion. The first group includes L+V type, low to medium salinity, and with homogenization temperature of 194 to 480°C. The second group includes V+L type, low to moderate salinity, and homogenization temperature of 338 to 448°C. The origin of L+V type fluid inclusions are magmatic-meteoric and metamorphic type and V+L fluid inclusions are metamorphic type. Mixing and dilution of fluids occurred during the mixing of meteoric waters with magmatic-metamorphic fluids. These processes are the main factors of mineralization in this deposit. Fluid inclusions data show that fluid pressure has been 50 to 150 bars during the ore-forming minerals. Also, the fluid temperature has been between 200 to 360°C. The data suggest that the ore minerals have been formed in depth of 650 meters lower than the old water table.
Economic Geology
maryam sadat lajouei kalaki; Afshin Akbarpour; Alexandre Tarantola; Shohreh Hassanpour; Behzad Mohammadi; Monireh Poshtkoohi
Abstract
The Gheshlaghe mil deposit is located in the Urumieh-Dokhtar magmatic belt. Vein- type mineralization is concordance within the rhyodacitic and rhyolite meta-tuff with Eocene age. Alteration zones of sericite, silica, argillic and iron oxides are observed in the investigated area. Primary sulfide minerals ...
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The Gheshlaghe mil deposit is located in the Urumieh-Dokhtar magmatic belt. Vein- type mineralization is concordance within the rhyodacitic and rhyolite meta-tuff with Eocene age. Alteration zones of sericite, silica, argillic and iron oxides are observed in the investigated area. Primary sulfide minerals of pyrite, fine-grained chalcopyrite and Oxidized specularite and Secondary minerals goethite, limonite, malachite and quartz in Microscopic and field studies have been identified. Based on X-ray diffraction analysis studies minerals such as chlorite, illite, kaolinite, hematite, quartz, mica group and calcite have been observed in the bearing gold veins. According litho-geochemical studies, the gold element has a positive correlation with iron, molybdenum, nickel and lead. A number of 157 fluid inclusion studies in the Gheshlaghe Mil ore mineralization area has been showed mineralization temperature of 99 to 299 °C, rate of salinity ore deposit 1.81 and 12.30 equivalent to the Nacl weight percent. Using Raman laser studies (13 points), the presence of gaseous phases (CO2, N2, H2O) in the fluid inclusions have been demonstrated. Regarding to studies have been done in this area, the Gheshlaghe Mil ore mineralization can to know to a vein type- hydrothermal bearing gold-copper ore deposit.
Economic Geology
Susan Ebrahimi; Alireza Arabamiri; Hadi Ghanbari
Abstract
The Sharifabad-Bardeskan copper mineralization is located in northeast of Bardeskan and south section of Sabzevar Zone. Mineralization occurs as vein in the pyroxene andesite, tuff, sandstone and conglomerate of Eocene age, which bearing local sericite - carbonate and silicic alterations and regional ...
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The Sharifabad-Bardeskan copper mineralization is located in northeast of Bardeskan and south section of Sabzevar Zone. Mineralization occurs as vein in the pyroxene andesite, tuff, sandstone and conglomerate of Eocene age, which bearing local sericite - carbonate and silicic alterations and regional propylitic alteration. Mineralization occurs as open space filling, disseminated, veinlets and consists of chalcocite pyrite, chalcopyrite, malachite, azurite with calcite and quartz as gangue minerals. Fluid inclusion studies in calcite show the evidence of mixing trend during the ore formation occurred at a wide range of temperature 200to 437 °C and varying salinity between 0.1 to 9.2 wt.% NaCl equivalent. The stable isotope composition of δ34S fall in a range of -23 to -24.3‰ could be considered as biogenetic sulfur from bacterial sulfate reduction. The δ13C values of calcite vary between -3.4 to -24.5‰ suggest a major contribution of marine carbonates associated igneous carbonates. Copper and sulfide rich hydrothermal fluid has flowed upward through the local faults and permeable interbeds within the Eocene volcanic sequence and formed the mineralized veins. Based on the mineralization, alteration, fluid inclusion and stable isotopes, Sharifabad mineralization is similar to those manto type deposits in Chile.
Economic Geology
Raziyeh Mahabady; Farajollah Fardoost
Abstract
Abgareh copper deposit located in 140 km southwest of shahrood and part of a volcanic-sedimentary Torud-Chah shirin belt that has facies in the northern edge Structural-sedimentary zones of Central Iran. Field and petrographical studies, deposit area, consist of andesite, basaltic andesite and basalt ...
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Abgareh copper deposit located in 140 km southwest of shahrood and part of a volcanic-sedimentary Torud-Chah shirin belt that has facies in the northern edge Structural-sedimentary zones of Central Iran. Field and petrographical studies, deposit area, consist of andesite, basaltic andesite and basalt and contains less includes tuffit crystal that indicate middle–upper Eocene with with argillitic, sericitic, silicic, carbonatic, chloritic and iron oxides alterations. According to the field observations and mineralogical studies, the mineralization in the region was carried out in two stages: hypogene and supergene and weathering. Hypogen zone minerals are generally pyrite, chalcopyrite and bornite. Because of existence in oxidizing-supergene environment , nearly almost Cu-bearing minerals of the main stage of mineralization have been replaced by secondary Cu minerals such as chalcocite, covellite, malachite and chrysocolla. Fluid inclusion data shows in the temperature range from 145 to 217 °C and salinity between 3.73 and 9.84 Wt%NaCl and depths less than 390 m. The host rocks, ore mineralogy, ore structures and textures, and fluid inclusions characteristics and comparison with similar epithelial deposits indicate that the Abgareh vein system is formed in a low-sulfidation epitermal environment.
Economic Geology
Maryam Javidi Moghaddam; M.H Karimpour; Azadeh Malekzadeh Shafaroudi
Abstract
The Rashidi area, which comprises a part of the north Khur in eastern Iran is located at 120 km northwest of Birjand city. Preliminary prospecting in the area using the image processing of ASTER data by Spectral Angle Mapper (SAM) algorithm resulted in the identification of propylitic and argillic alteration ...
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The Rashidi area, which comprises a part of the north Khur in eastern Iran is located at 120 km northwest of Birjand city. Preliminary prospecting in the area using the image processing of ASTER data by Spectral Angle Mapper (SAM) algorithm resulted in the identification of propylitic and argillic alteration zones together with iron oxy-hydroxide minerals. The area consist of outcrops of Eocene pyroclastic rocks ranging from andesitic to rhyolitic in composition, intruded by diorite porphyry dikes. Vein mineralization in the area was mainly occurred along a fracture system hosted by andesitic tuff breccia unit. Vein copper mineralization was formed during two stages including the: (1) quartz-pyrite-chalcocite-tennantite assemblage, and (2) quartz-chalcocite-pyrite-sphalerite assemblage. The values of δ18O for quartz in the first and second stages of vein mineralization was 19.26 and 14.94 and the amount of δ18O water in equilibrium with quartz was 10.96 and 4.94 respectively that shows a magmatic origin and mixing with meteoric water in the second stage. Based on geology, vein geometry, fluid inclusion, and stable isotope geochemistry, the Rashidi Cu deposit can be classified as vein-type copper deposits, which has been formed along fault zones.
Economic Geology
Mohammad Jabarian; mehrdad karimi; Mohammad Lotfi; kamal noori khankahdani
Abstract
Dehkooye salt dome is located 30 km northeast of Lar in Fars province, Iran. The salt dome occurred in Zagros folded zone where infracambrian thick evaporate strata (Hormoz series) intruded Cenozoic sedimentary rocks. Core of the dome mainly made up of salt and gypsum and overlain by marl, gypsum, limestone, ...
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Dehkooye salt dome is located 30 km northeast of Lar in Fars province, Iran. The salt dome occurred in Zagros folded zone where infracambrian thick evaporate strata (Hormoz series) intruded Cenozoic sedimentary rocks. Core of the dome mainly made up of salt and gypsum and overlain by marl, gypsum, limestone, and dolomitic formations. Besides primary stratiform mineralization, epigenetic iron and copper mineralization occurred mostly within dolomitic lime stone members in the cap rock of the salt dome in Hormoz Formation. Ore mineralogy is simple and includes hematite, minor goethite, and sparse occurrence of magnetite. Chalcopyrite is evident as minor phase. Samples for fluid inclusion studies were collected from sulfide-bearing quartz veins and veinlets. According to homogenization temperature (Th: 172-374 ° C with average 374° C), which in fact represents the boiling point of the irrigation solution, indicate the epithermal to the beginning of hypothermal conditions and the mean of the beginning of the mesothermal. The depth formation of deposit was between 50 to 1500 meters and an average of about 200 meters. The hydrothermal solutions forming the ore deposit, due to their high salinity, have the origin of magmatic brine that have been displaced because of low density and tectonic pressures. This solutions have climbed upwards along faults and fractures and after being mixed with meteoric waters, epigenetic mineralization is created.
Exploration and Mining
Maliheh Abbaszadeh; Ardeshir Hezarkhani; Saeed Soltani-Mohammadi
Abstract
In recent years, economic geology studies have become very popular method in mineral exploration studies. Modeling fluid inclusion data is one of the common studies in economic geology. In this research artificial neural networks method, as one of the machine learning algorithms, is used for three-dimensional ...
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In recent years, economic geology studies have become very popular method in mineral exploration studies. Modeling fluid inclusion data is one of the common studies in economic geology. In this research artificial neural networks method, as one of the machine learning algorithms, is used for three-dimensional modeling and application of the results of fluid inclusion analysis in Sungun porphyry copper deposit. For this purpose, fluid inclusion data is used for directly separation of related alteration zones with mineralization (Potassic, Phyllic and Potassic- Phyllic). Due to the relation that exists between alteration zones and mineralization areas, based on 173 fluid inclusion data the separation of alteration zones is modeled by artificial neural networks method in Sungun porphyry copper deposit. According to the validation studies, it can be concluded that precision of this model is appropriate (83%) and trained model could be used for separation of alteration zones in Sungun porphyry copper deposit.
R. Pourmasoomi; A. R. Jafari rad; M. Lotfi; P. Afzal
Abstract
The Khankeshi stratabound copper deposit is located in Markazi province, 80 Km SW of Tehran. The area is covered by a sequence of E-W trending lava flows and pyroclastic of Late Eocene age. The volcanic rocks can be classified as trachyandesite and andesite.The rocks contain a ...
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The Khankeshi stratabound copper deposit is located in Markazi province, 80 Km SW of Tehran. The area is covered by a sequence of E-W trending lava flows and pyroclastic of Late Eocene age. The volcanic rocks can be classified as trachyandesite and andesite.The rocks contain a high fraction of potassium calc-alkaline and their geochemical characteristics attribute them to back arc basin and extentional processes. The oldest rocks of the study area are Elta unit , composed of green andesitic tuff located in south eastern of the khankeshi. This part indicates a basin with volcanic activities and exhalites, and green tuff with thin lamination combined with microcrystalline carbonates. On the other hand, presence of carbonate of micrite with framboidal pyrite in this part indicated reducing environment and Exhalites activity by source of sulfur in manto type mineralization in the khankeshi. The host rock is Elt type latite andesite with mega porphyritic texture and involved major ore chalcopyrite, bornite with pyrite and minor chalcocite, covellite, hematite, Goethite and malachite with dolomite and dolosparite veins. Framboidal pyrite is replaced with forms of fine and circle chalcopyrite and bornite in primary micritic background and subhedral crystals into dolosparite veins of crystallized micrititic carbonate micrite in forms of epigenetic that produce the supergene secondary production. This unit with pyroclastics and tuff breccias(Elta unit), indicated volcanic cycle that mineralization of copper, in forms of stratabound, has taken place in it. Local alteration associated with copper mineralization includes weak chloritization, oxidation with local argillic, serecitic and zeolitic. Mineralization is stratabound and copper mineralization occurs as disseminated, vein-veinlet,open space fillings and replacements. Based on fluid inclusion studies on coexisting calcite, Homogenization temperatures are between 129.4 to 227.1(with an average of 175°C).Salinity varies between 1.91 to 13.40(average 12) wt٪ NaCl eq. The depth of fluid inclusion trapping is estimated to be less than 200 meters and ore formation has occurred at pressure values less than 74 bars. Geological, ore mineralogy, ore texture, structures and fluid inclusions characteristics in the khankeshi deposit are similar to those reported from Manto type copper deposits.
Economic Geology
H Tajeddin; Ebrahim Rastad; Abdolmajid Yaghoubpour; Mohammad Mohajjel; Richard Goldfarb
Abstract
Barika gold (and silver)-rich volcanogenic massive sulfide deposit is located 18 km east of Sardasht city in the northwestern of Sanandaj–Sirjan metamorphic Zone. The rocks in the vicinity of the Barika deposit predominantly consist of Cretaceous volcanosedimentary sequences of phyllite, slate, ...
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Barika gold (and silver)-rich volcanogenic massive sulfide deposit is located 18 km east of Sardasht city in the northwestern of Sanandaj–Sirjan metamorphic Zone. The rocks in the vicinity of the Barika deposit predominantly consist of Cretaceous volcanosedimentary sequences of phyllite, slate, andesite and tuffite, metamorphosed under greenschist facies grade. Barika deposit is composed of stratiform ore and stringer zone that both are hosted in an altered and sheared metaandesite unit. Fluid inclusion studies indicated that quartz (stringer zone) and barite (stratiform ore) samples homogenized between 132° and 283°C. Salinities of the fluids inclusions show a range from 1.4 to 9.6% wt NaCl equivalent that are close to that of normal seawater. The study indicates the colling occurred in the initial ore fluids, as a result of mixing with sea water, is an important process in the formation of Barika deposit. The δ34S values of sulfide minerals (pyrite, sphalerite and galena) from stockwork mineralization in the Barika deposit range from -0.8 to +5.6 per mil and fall within the range of values observed for volcanogenic massive sulfide deposits. The narrow range of measured δ34S values from the sulfide minerals suggests that similar to almost of Kuroko VMS deposits, the ore-forming sulfur derived from the leaching of igneous sulfur from the underlying andesitic rocks. Calculated sulfur isotope temperatures for twelve coexisting galena-sphalerite and galena-pyrite pairs range from 146-293 ْ C that is consistent with temperatures estimated from fluid inclusion studies.
M. R. Rezapour; V. Simmonds; M. Moazzen; R. Hajialioghli
Abstract
The Qohrud granitoid body of Miocene age is located 40 km SW Kashan, ranging in composition from granite through granodiorite to tonalite. Hydrothermal activities following the magma intrusion have brought about formation of various coarse automorphic and colored quartz crystals within the fractures ...
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The Qohrud granitoid body of Miocene age is located 40 km SW Kashan, ranging in composition from granite through granodiorite to tonalite. Hydrothermal activities following the magma intrusion have brought about formation of various coarse automorphic and colored quartz crystals within the fractures and cavities of different lithologies. The quartz crystal varieties include transparent, semi-transparent, pale green, yellow and black crystals, as well as those with smoky and reddish brown roots and also crystals containing tiny acicular rutile inclusions. Mineral chemistry, as well as fluid and solid inclusion studies on the colored and automorphic quartz crystals indicate that various physical and chemical factors, such as temperature, pressure, magma and host rock compositions, hydrothermal fluids and the associated alterations, as well as pH and Eh were involved in the formation of these automorphic colored crystals. The solid inclusions within these automorphic quartz crystals might have formed in two ways: 1) introduction of the necessary elements for the formation of quartz and the solid inclusions by the fluids and then, entrapment of these inclusions within the growth layers of quartz crystals; 2) direct introduction of very fine mineral particles within the growth layers of quartz, leading to occurrence of various colored crystals. Smoky crystals can be formed by the replacement of Si by Al and also by the presence of U and Th within them. The reddish color of quartz crystals was recognized as the result of the presence of fine rutile needles. Automorphic black-colored quartz crystals are formed at oxidant and almost high pH conditions by initial precipitation of magnetite and then, manganese oxides at the outermost growth layers. The green quartz crystals have been resulted from chloritic and epidotic alterations within the host and neighboring rocks.
Economic Geology
Behzad Hamamipour; H. A. Tajeddin; Leila Barahmand
Abstract
The Sebandoon gold deposit is located 40 km north of the Bardaskan in the northern part of the Central Iran. The rock units exposed in the area consist of upper Cretaceous volcano-sedimentary sequences of trachyte-trachyandesite, andesibasalt,tuff and carbonaceous shale which intruded by post Eocene ...
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The Sebandoon gold deposit is located 40 km north of the Bardaskan in the northern part of the Central Iran. The rock units exposed in the area consist of upper Cretaceous volcano-sedimentary sequences of trachyte-trachyandesite, andesibasalt,tuff and carbonaceous shale which intruded by post Eocene syenite-quartz monzonite subvolcanic intrusions and diabasic dikes. The main gold reservoir in the Sebandoon deposit has occurred in cone-shaped and mostly in the trachyte-trachyandesite lava with dimensions of 90×150 m in the surface which continue up to the depth of 70 m. The hydrothermal alterations occurred in the deposit area include silicic, sulphidic, partly argillic (supergen) and propylitic which two former contains most of the high grade gold ores. The main ore structures and textures in the deposit are vein-veinlets (stockwork) and breccia which consists of quartz, sulphide minerals and rare adularia. Primary ore mineral assemblages of the deposit are simple and consist of pyrite, sphalerite, chalcopyrite, bornite, galena, arsenopyrite and gold. Covellite, chalcocite and iron hydroxides are secondary minerals in the deposit. Gold grains with less of than 60 microns in size has been found as inclusion in pyrite and chalcopyrite, in sulfides rims and intergrowth with quartz. Fluid inclusion studies on ore-bearing quartz reveal that majority of primary inclusions are liquid-rich two-phase (LV). The studies indicate homogenization temperatures between 165 and 254°C and salinity between 0.9 to 7.8 wt% NaCl eq. Comparison of the main characteristics of the Sebandoon deposit with epithermal gold deposits reveals that the geology, alteration, ore mineralogy, geochemical characteristics and fluid inclusions of the Sebandoon gold deposit is similar to low to intermediate-sulphidation type epithermal deposits.
S. N. Haghighi Bardineh; R. Zarei Sahamieh; H. Zamanian; A. Ahmadi Khalaji
Abstract
The Takht iron deposit is located 120 km northeast of the Hamedan City in the Urumieh-Dokhtar magmatic belt. The Miocene Takht granodiorite intruded into the Cretaceous carbonates and resulted in Fe-skarn formation. Epigenetic mineralization in the Takht Deposit occurred predominantly as vein and lenticular ...
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The Takht iron deposit is located 120 km northeast of the Hamedan City in the Urumieh-Dokhtar magmatic belt. The Miocene Takht granodiorite intruded into the Cretaceous carbonates and resulted in Fe-skarn formation. Epigenetic mineralization in the Takht Deposit occurred predominantly as vein and lenticular ore bodies accompanied with argillic, carbonation, chloritization, epidotization and silicfication alterations and minerals including garnet, pyroxene, epidote, tremolite- actinolite, phlogopite, hornblende, quartz, calcite, magnetite, pyrite, specularite, chalcopyrite, hematite, limonite, goethite and malachite. Chemical composition indicates the presence of Si, Al, Ca, Mg, Ti and chalcophile elements such as Cu, Zn, As and Pb that originate from the coexistence of silicate and sulfide minerals with magnetite. The microthermometric results revealed homogenization temperatures (Th) from 153.2°C to 338.3°C and salinity from 0.827 wt.% NaCl eq. to 25.36 wt.% NaCl eq.. The δ18O (SMOW) values of magnetite were measured in the range of −0.46‰ to +2.31‰ and δ18O water is +8.1‰ to +10.9‰, respectively. These isotope values are similar to magmatic fluids that were also equilibrated with 18O enriched sources. The δ34S (V-CDT) values of pyrite show ranges of +7.3‰ to +12.5‰ and the original fluid δ34S H2S values were estimated ranging from +5.7‰ to +10.9‰. These positive δ34S values confirm that sulfur is provided by evaporate sulfates. During the retrograde stage of the Takht Skarn, re-mobilized metals accompanied with metal-bearing fluids (provided by intrusion) were mixed with sulfur-bearing descending meteoric waters and eventually, the mixing of the two fluids led to calcic Fe-skarn mineralization in Cretaceous carbonates.
M. R. Hosseini; S. Alirezaei; J. Hassanzadeh
Abstract
The Bahr Aseman volcanic-plutonic complex is located to the southeast of the Kerman magmatic belt. Unlike Kerman magmatic belt which formed and evolved during Cenozoic in a dominantly continental arc and post-collision tectonic setting, Bahr Aseman complex formed during Late Cretaceous in an oceanic ...
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The Bahr Aseman volcanic-plutonic complex is located to the southeast of the Kerman magmatic belt. Unlike Kerman magmatic belt which formed and evolved during Cenozoic in a dominantly continental arc and post-collision tectonic setting, Bahr Aseman complex formed during Late Cretaceous in an oceanic island-arc setting. The complex is composed of andesitic and andesitic-basaltic lava flows and subordinate pyroclastic materials and carbonate interlayers, as well as abyssal tonalite to quartz-diorite and quartz- monzodiorite intrusive bodies and shallow dioritic intrusions. Vein- type copper deposits, iron skarn and copper skarn are the main ore deposit types in Bahr Aseman. Chalcopyrite is the main ore mineral in vein-type and skarn-type copper deposits; the mineral is converted to oxide copper ores at surface and shallow depths. Magnetite is the main commodity in skarn type iron deposit. Highly altered porphyritic bodies associated with copper oxide ore were identified that are comparable, in some aspects, with porphyry type copper deposits; subsurface data, however, is required for conclusive remarks. The various types of deposits are distinguished by distinct fluid inclusion characteristics. In the vein type copper deposits, fluids in association with mineralization represent dominant homogenization temperature (Th) of 150-220 ºC and salinity of 5-10 and 25-30 wt% NaCl. Fluids in the skarn type copper deposits represent 170-250 ºC and ranges of 5-15 and 27-35 wt% NaCl as dominant Th and salinity, respectively. The δ34S values in the vein-type copper deposits vary between +3.9 and +5‰, suggesting a magmatic origin for sulfur and probably metals (directly derived from magma or leached from magmatic rocks). Sulfur isotope ratios for two samples from Moka are +4.3 and +7.1‰, slightly different from typical magmatic δ34S ranges. Oxygen and hydrogen isotope ratios for the vein-type copper deposits, measured on quartz and fluids extracted from inclusions in the mineral, are -6.6 to +1.9‰ and -79.4 to -51.8‰, respectively. This values suggest mixing of magmatic and meteoric fluids and/or fluid-rock interactions at different ratios. It appears that larger deposits have more shares of fluids with magmatic origin. With regards to the island-arc tectonic setting, recognized deposit types and ore minerals paragenesis, finding new copper and iron and probably gold deposits are possible in the Bahr Aseman area.
M.R Hosseinzadeh; S Maghfouri; M Ghorbani; M Moayyed
Abstract
The study area is located in Arasbaran metallogenic zone. Rocks of the Sonajil region include Eocene andesite lava, porphyry microdiorite, Incheh granitoid and Ozuzdaghi Plioquaternary volcanic rocks. Porphyry microdiorite is the main host rock of porphyry type Cu- Mo mineralization in the Sonajil deposit. ...
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The study area is located in Arasbaran metallogenic zone. Rocks of the Sonajil region include Eocene andesite lava, porphyry microdiorite, Incheh granitoid and Ozuzdaghi Plioquaternary volcanic rocks. Porphyry microdiorite is the main host rock of porphyry type Cu- Mo mineralization in the Sonajil deposit. Much of the mineralization in the Sonajil deposit is dispersive and vein- veinlet type. Based on the structure, mineralogy and texture, the Sonajil vein- veinlets can be divided into sex different groups. These veins - veinlets contains sulfide (pyrite, chalcopyrite, molybdenite, bornite, galena, tetrahedrite, tenantite and enargite), hydroxide and oxide (magnetite and spicularite) and carbonate (malachite and azurite) minerals. Various types of fluid inclusions including mono-phase vapor, two-phase liquid and vapor, and multiphase liquid-vapor-solid of primary origin are present within quartz-sulfide veinlets.TH (L-V) for halite-bearing inclusions homogenizing by disappearance of halite and of vapor are 260-565˚C, 320-520˚C, respectively and salinity are 35.3- 69 % NaCl. TH (L-V) for two-phase inclusions homogenizing temperatures are 180-565˚C, and salinity are 0.7- 15.17 % NaCl. In bivariate plot of TH-salinity, two distinct populations of high and low salinity fluids are recognizable and most of the data points relating to the high salinity plot above the halite saturation curve. The coexistence of vapor-rich two-phase and halite-bearing inclusions having similar TH ranges can be indicative of boiling in the Sonajil porphyry deposit.
Economic Geology
A. Baharvandi; M. Lotfi; M. Ghaderi; M. R. Jafari; H. A. Tajeddin
Abstract
Shekarbeig barite deposit is located 46 km southwest of Mahabad in northwestern part of the Sanandaj-Sirjan zone. The outcropped rock units in the area are Late Protrozoic metamorphosed volcano-sedimentary rocks, equivalent to Kahar Formation. The main ore mineral occurs as stratiform barite lenses in ...
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Shekarbeig barite deposit is located 46 km southwest of Mahabad in northwestern part of the Sanandaj-Sirjan zone. The outcropped rock units in the area are Late Protrozoic metamorphosed volcano-sedimentary rocks, equivalent to Kahar Formation. The main ore mineral occurs as stratiform barite lenses in three horizons accompanied by sulfide minerals as massive and/or parallel bands within metamorphosed rhyolitic tuffs (metatuff). The deposit footwall is composed of phyllite and slate crosscut by silicic and sulfide-bearing barite veins and veinlets (stringer zone). Primary minerals in the ore are mainly barite, pyrite, marcasite, chalcopyrite and bornite and secondary minerals are chalcocite, covellite, malachite, siderite, goethite, hematite and other iron hydroxides. Gangue minerals include quartz, sericite, calcite, dolomite, feldspar and chlorite. In terms of metallic ores, the Shekarbeig deposit does not vary much having only pyrite and chalcopyrite. Types of fluid inclusions in the Shekarbeig deposit are two-phase liquid-vapour (LV), mono-phase vapour and mono-phase liquid; two-phase liquid-vapour being the dominant type in both stringer and stratiform parts. Sulfur isotope data indicate that seawater was the main mineralizing fluid for Shekarbeig mineralization. These data suggest that complete reduction of recent seawater sulfate and the rate of mixing of hydrothermal solution with cold waters in deep parts of the basin may result in precipitation of large amount of sulfides in the stringer and stratifrom zones. On the other hand, partial reduction of recent seawater sulfates provided required sulfur for the deposition of barite. Geological evidence, evaluation, lithostratigraphy, mineralization geometry and the results of fluid inclusion and sulfur isotope studies for samples from the Shekarbeig deposit indicate derivation of the hydrothermal fluids of low salinity and moderate temperature from seawater and circulation and upward movement by a heating source (probably subvolcanic intrusions) and finally cooling and deposition of the fluids as sulfate and sulfide on the sea floor due to mixing with seawater, similar to massive sulfide Kuroko-type deposits.
F Padyar; M Rahgoshay; S Alirezaei; M Pourmoafi; A Tarantola; O Vanderhaeghe; M Caumon
Abstract
The Latala base and precious metals deposit is hosted by quartz veins, associated with a porphyry pluton intruded into a Cenozoic volcanic sequence. Euhedral quartz with sulfide mineralization such as pyrite, chalcopyrite, galena and sphalerite, with minor sulfosalts occurs in these veins as open space ...
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The Latala base and precious metals deposit is hosted by quartz veins, associated with a porphyry pluton intruded into a Cenozoic volcanic sequence. Euhedral quartz with sulfide mineralization such as pyrite, chalcopyrite, galena and sphalerite, with minor sulfosalts occurs in these veins as open space fillings and minor replacement bodies. Progressive growth of quartz crystals is evidenced by their texture revealed by cathodoluminescence imaging. The analysis of fluid inclusions indicate a decreasing homogenization temperature from 350°C in the core to 135°C along the edge of the quartz crystals with overgrowths. The presence of CO2 vapor suggested by the thermometric analysis is confirmed by Raman spectrometry. The solid phases in fluid inclusions identified as phyllosilicates, presumably muscovite and illite, chlorite, quartz and carbonate-mineral such as (Natrocarbonate, Dawsonite) by petrography and Raman spectrometry. Solid phase of halite were identified in two fluid inclusions. The homogenization temperature and salinity varies between 131 to 380 °C and 0.17 to 7.7 wt.% NaCl eq respectively. The properties of fluid inclusions corresponds to a magmatic hydrothermal fluid circulating from depth to shallower environments. The sulfur isotopic composition for galena, sphalerite, chalcopyrite and pyrite varies between -9.8 and -1‰, which correspond to values of magmatic sulfur. The δ34S values from +1.8 to -9.2‰ are in the range of hydrothermal fluids. Fluid inclusions features show a magmatic hydrothermal source which transported magmatic fluid and vapor from the depth through fractures to shallow environment. It suggests that magmatic water mixing with meteoric water was responsible for transportation of metals in Latala. Epithermal mineral precipitation during boiling, mixing and water-rock interaction formed hydrothermal quartz and sulfide mineralization. The available evidence suggests that the hydrothermal fluids changed from magmatic to epithermal in the region.
A Hosseinkhani; M.H Karimpour; A Malekzadeh Shafaroudi
Abstract
The SW Sorkh-Kuh area makes part of the Tertiary volcanic-plutonic rocks in the west of the Lut Block, SW of Birjand city. Geology of this area consists of andesitic and basaltic volcanic rocks intruded by hornblende diorite, hornblende microdiorite, hornblende diorite porphyry, hornblende quartz diorite ...
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The SW Sorkh-Kuh area makes part of the Tertiary volcanic-plutonic rocks in the west of the Lut Block, SW of Birjand city. Geology of this area consists of andesitic and basaltic volcanic rocks intruded by hornblende diorite, hornblende microdiorite, hornblende diorite porphyry, hornblende quartz diorite porphyry and biotite quartz monzonite, which caused extensive alteration and mineralization. The vein mineralization with a NW-SE trend have been observed in the NW portion of the area which is composed of quartz, chalcopyrite, pyrite and Fe-Cu secondary minerals. This vein is the youngest occurrence of mineralization, related to intrusive rocks, in the Lut Block (after Miocene). Primary fluid inclusions of quartz in paragnesis with mineralization, revealed three types of two phases inclusions with difference in density, which liquid rich phases have an average 270 and 330°C of homogenization temperature. Based on freezing studies, calculated temperature of last melting point of these fluids equals to 12-15 and 16-19% wt eq. NaCl, respectively. Some fluids, which homogenized to gas, have more homogenization temperature and salinity. In evaluation of depth, using homogenization temperature, salinity, density and pressure of fluid inclusion, 700 m depth was calculated for mineralization, corresponding to the present erosion surface. δ18O values of quartz in mineralized vein and fluid in equilibrium with quartz have a range between +8.66 – +13.09‰ and +3.06 – +7.59, respectively. It could be inferred that the source of ore-forming fluids was magmatic in the mineralized vein. In general, stable isotope and fluid inclusion studies show similarity of mineralization of the SW Sorkh-Kuh with epithermal deposits in which mineralization is related to the dioritic intrusive rocks. The changes in fluid composition and boiling resulted in mineraliztion along a fault as vein.
L Salehi; I Rasa; S Alirezaei; A Kazemi Mehrnia
Abstract
The Madan Bozorg deposit is located in the Abbas Abad mining district, about 130 km east of Shahroud. The area is covered by a NE-SW trending belt of intermediate-mafic lava flows and pyroclastic materials, as well as interlayered sedimentary rocks. Eight copper deposits have been identified in the district. ...
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The Madan Bozorg deposit is located in the Abbas Abad mining district, about 130 km east of Shahroud. The area is covered by a NE-SW trending belt of intermediate-mafic lava flows and pyroclastic materials, as well as interlayered sedimentary rocks. Eight copper deposits have been identified in the district. Based on the chemistry, the volcanic rocks can be classified as trachyandesite, trachyandesitic basalt and trachybasalt; the rocks display high potassium calc-alkaline to shoshonitic affinities and bear geochemical attributes characteristic of continental arc settings. The Madan Bozorg deposit is hosted in trachyandesite with porphyritic to megaporphyritic, glomeroporphyritic and amygdaloidal textures. Based on field observations, microscopic studies, Raman spectroscopy and XRD results, two types of alteration, regional and local, can be distinguished. The regional or background alteration, is comparable to a propylitic assemblage and occurs in mineralized and non- mineralized volcanic units. Local alteration associated with copper mineralization includes calcic, silicic, sericitic, chloritic, zeolitic and hematitic. Copper mineralization occurs as disseminated, vein- veinlet, replacement, stockworks and irregular open space fillings. Based on microscopic studies and EPMA data, chalcocite group minerals (chalcocite, djurleite, anilite, digenite and covellite) are the main ore minerals and are accompanied by subordinate bornite, pyrite and hematite. Secondary minerals include covellite, malachite, azurite, chrysocolla and goethite. Nonmetallic minerals are quartz, chlorite, epidote, calcite, and chalcedony. Based on fluid inclusion studies on coexisting quartz, homogenization temperatures are between 90 to 268°C with an average of 176° C. Salinities vary between 3.38 to 21.96 (average, 13.21) wt% NaCl eq. Fluid density varies between 0.8 to 1.1 g.cm-3. The depth of fluid inclusion trapping is estimated to be less than 200 meters, and ore formation occurred at pressures less than 50 bars. The host rocks, ore mineralogy, ore textures and structures, and fluid inclusions characteristics in Madan Bozorg deposit are similar to those reported from Manto type copper deposits in Mesozoic-Cenozoic volcanic belts in South America and elsewhere.
H Zamanian; Sh Rahmani; M.R Jannessary; R Zareii Sahamiieh; B Borna
Abstract
Lohneh gold and copper deposits lay in the north west of Iran, 100 kilometers north of Zanjan province. Lohneh mining area is a part of the Tarommetallogenic zone in the Alborz-Azerbaijan region. The presence of numerous minerals, slag melting of mining activities (such as cows and exploratory pits, ...
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Lohneh gold and copper deposits lay in the north west of Iran, 100 kilometers north of Zanjan province. Lohneh mining area is a part of the Tarommetallogenic zone in the Alborz-Azerbaijan region. The presence of numerous minerals, slag melting of mining activities (such as cows and exploratory pits, tunnels) in the Armenian fortress (by Armenian miners) shows that the mineral reserve Lohneh have been considered by old miners. There are 9 gold bearing quartz veins .Two main quartz vein with a length of 500 meters and a width of one meter (visible on the Earth). Rock outcrops in the area consist of the Eocene-Oligocene volcanic rocks (tuffs, tuff breccia, trachyandesite) and intrusive rocks (granodiorite, quartz monzonite, monzonite). On the basis of geochemistry study, intrusive rocks is resemble the I-Type granitoids and from a magmatic stand point, the rocks of the area are calc–alkaline, and tectonically they belong to the continental margin and subduction zones. Tuff breccia rocks cut by quartz monzonite and has been altered. The major alteration of the areas consists of silicious, sericitic, and argillic alteration. The main gold minerals have occurred in tuff breccia rocks and a small amount of gold mineral in quartz monzonite. Gold mineralization in the Lohneh area is in the form of open space, vein-veinlet and hydrothermal breccia. According to chemical analysis of gold mineralized samples gold grade is in the range of at least 0.002 to 10ppm. The average gold grade is 4.35ppm. Mineralogy of Lohneh deposit has a metallic minerals (oxide, sulfide) and non-metallic (silicate and carbonate) which is composed of two phases hypogene and supergene. Metallic minerals are including gold particles (free in siliceous gangue and visible under a microscope and SEM study), silver (in the free form in siliceous and involved in galena and tetrahedrite network), pyrite, chalcopyrite, bornite, galena, sphalerite, and tetrahedrite. Non-metallic minerals or gangue consist of quartz, hydrothermal alkali feldspar (adularia), sericite, clay minerals, calcite, and small amount of barite. According to geochemical studies (table correlation of elements, graph clustering and component plot in rotated space) gold with Ag(0.78), cu(0.81), As(0.7), Pb(0.64), Zn(0.6), S(0.4), Bi(0.45), U(0.3), Mo(0.25) is a significant correlation. This correlation geochemistry is corresponded with mineralography evidence (mineral paragenesis sequence) and SEM studies. Fluid inclusion study was performed on primary, large size and rich liquid fluid inclusions on quartz mineral (concurrent with the formation of gold and sulfide minerals).Fluid inclusion data shows in the temperature range from 125 to 290 °C and salinity between 1 and 6.5 wt% NaCl and depths less than 1000 m. Fluid inclusion evidence shows cooling effect, boiling and formation of solutions with high salinity and density of the ore forming fluids in Lohneh deposits. Adularia mineral, calcite, bladed and comb quartz and hydrothermal breccia are evidence of boiling effect in the Lohneh deposits.Evidence of the presence of epithermal textures (banded, comb, blade, and hydrothermal breccia), sericitic alteration, and sulfide minerals such as galena, sphalerite, chalcopyrite, tetrahedrite, and fluid inclusions evidence (temperature, salinity, density, vapor-rich inclusions) indicates intermediate sulphidation epithermal gold deposits in Lohneh area.