Economic Geology
Mostafa Esmaeili-Vardanjani; Mostafa Nazeri; Gholamreza Asgari
Abstract
Gilsonite mineralization in Shak Meydan zone as the most prone zone of Iranian gilsonite mineralization was predominantly hosted by the anidrite part of Asmari Formation (Kalhor member) and Gachsaran Formation. To find the prospect areas of gilsonite mineralization in ShakMeydan zone, the zone was divided ...
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Gilsonite mineralization in Shak Meydan zone as the most prone zone of Iranian gilsonite mineralization was predominantly hosted by the anidrite part of Asmari Formation (Kalhor member) and Gachsaran Formation. To find the prospect areas of gilsonite mineralization in ShakMeydan zone, the zone was divided into three sub zones in which exploration studies were conducted. We first tried to determine lithologic units using remote sensing processing and to separate rock units using image processing technology. Next, we plotted a 3D structural modeling of the study zone in order to increase the depth precision and to determine the stratigraphic sequence and stratigraphy-structural adaptation. Finally, we detected structural controllers including faults and existing breaks in each sub zone and circular structures prone to translocate minerals. In the sequel, we assigned appropriate weights to applied information layers including geological, tectonic, mineral information and the results of remote sensing studies using analytical hierarchy process (AHP) based on Knowledgeable information and field studies to synthesized the exploratory data in order to introduce the prospect areas with exploration priority.
Economic Geology
A. R. Zarasvandi; Fatemeh Davoodian Ranjbar; Mohsen Rezaei; M. Tashi; Houshang Pourkaseb
Abstract
Sarkuh porphyry copper deposit is located 180 km west of Kerman province, 6 km southwest of Sarcheshmeh porphyry copper mine in the northeast of Pariz city. Considering geological divisions, it is a part of Urumieh-Dokhtar magmatic arc. The exposed rocks in this area are mainly composed of volcanic units, ...
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Sarkuh porphyry copper deposit is located 180 km west of Kerman province, 6 km southwest of Sarcheshmeh porphyry copper mine in the northeast of Pariz city. Considering geological divisions, it is a part of Urumieh-Dokhtar magmatic arc. The exposed rocks in this area are mainly composed of volcanic units, tuffs, andesite and basaltic andesite. Also intrusive units include granite to granodiorite, and to a lesser extend quartz diorite rocks. Major alterations of the deposit include potassic, phyllic, argillic and propylitic, as well as intermediate alterations such as potassic - argillic and potassic - phyllic. The purpose of this research is to study the chemical features of biotite and chlorite in order to investigate the physicochemical attributes of porphyry system during magmatic to hydrothermal transition in the patassic alteration. Based on the temperatures of reequilibrated biotite, at the time of magmatic to hydrothermal transition, the temperature ranged from 343 to 397°C. Also high magnesium nature of biotites, and their plotting in the boundary of magnetite-hematite (HM) and nickel-nickel oxide (NNO) buffering lines, as well as presence of magnetite with hematite rims indicate previlling of the high oxygen fugacity during potassic alteration.
Economic Geology
SHAHRAM RAHMANI; Hasan Zamanian; reza Zarei Sahamieh
Abstract
Abstract: The study area is located 45Km NE Zanjan in the Azerbaijan-Western Alborz zone. Quartz-monzonite and dacitic brecciated tuffs are the main host rocks to the Lubin-Zardeh deposit. These rocks are predominantly of K-high calc-alkaline shoshonitic I-type, metaluminous magnesian affinities of Cordilleran ...
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Abstract: The study area is located 45Km NE Zanjan in the Azerbaijan-Western Alborz zone. Quartz-monzonite and dacitic brecciated tuffs are the main host rocks to the Lubin-Zardeh deposit. These rocks are predominantly of K-high calc-alkaline shoshonitic I-type, metaluminous magnesian affinities of Cordilleran type. The intrusive rocks are enriched in LILE, LREE and depleted from HFSE, MREE and HREE and Y. A listric-shaped REE pattern and average La/Yb ratios of host rock indicates higher water content and fO2 in the magma and hornblende fractionation. Their relatively low to moderate ISr values (0.7047–0.7051), positive εNd (t = 36 Ma) values (0.39–2.1) and TDM ages of 0.69 to 1.06 Ga, with Pb isotopic ratios of (206Pb/204Pb) i = 18.49–18.68, (207Pb/204Pb) i = 15.58–15.61 and (208Pb/204Pb) i = 38.33–38.77. Based on textural evidence (coarse amphibole crystals), geochemical data (major, trace and Rare earth elements) and isotopic contents of Pb, Sr-Nd, it is suggested that these rocks correspond to geochemical and isotopic compositions of the host rocks of porphyry and epithermal deposits in the Urmia Dokhtar zone of West Alborz-Azerbaijan (Arasbaran) and Eastern Pontides epithermal deposits, Turkey.
Economic Geology
nader taghipour; Tahereh Rabani; Reza Zahiri
Abstract
Coal deposits in Gheshlagh region are embedded in the sediments of Shemshak formation with lithological units such as sandstone, conglomerate, siltstone, limestone and argillite. For investigation of mineralogy and structural characteristics of Gheshlagh coal seams sampled of eleven coal seams in four ...
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Coal deposits in Gheshlagh region are embedded in the sediments of Shemshak formation with lithological units such as sandstone, conglomerate, siltstone, limestone and argillite. For investigation of mineralogy and structural characteristics of Gheshlagh coal seams sampled of eleven coal seams in four active mines. Occurrence of minerals with distribution and nature of organic – mineral bonds in coals seams of this region is considered by using of petrographic and XRD and FT-IR analyses. Study of hand specimen and polished section are approved the presence of clay minerals, pyrite, chalcopyrite, siderite and quartz. Also The presence of minerals like kaolinite, quartz, siderite, dolomite, calcite, pyrite, montmorillonite and biotite was revealed by XRD. Mineral–organic bands such as: OH, CO2, CH3, Si-O, S-S, C-S, Al-OH, carbonate minerals, C=C, aromatic and aliphatic CH have been identified by the FT-IR in Gheshlagh coal seams. Raman spectroscopic confirms the presence of the graphitic band (G) (1581 cm−1- 1585 cm−1) and the defect band (D1) (1341 cm−1 – 1352 cm−1) in Gheshlagh coal seams. Graphitic bands contain high intensity and insignificant broadening.
Economic Geology
shahriar keshtgar; Sasan Bagheri; shahriar keshtgar
Abstract
Abstract The Mahirud volcano-plutonic Complex (MVPC), known as Cheshmeh Ostad Group, an rock assemblage including several plutons and volcano-sedimentary successions, crops out at the northeastern part of the Sistan Suture Zone. Igneous rocks of the MVPC, consist of volcanic lavas and pyrclastic rocks, ...
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Abstract The Mahirud volcano-plutonic Complex (MVPC), known as Cheshmeh Ostad Group, an rock assemblage including several plutons and volcano-sedimentary successions, crops out at the northeastern part of the Sistan Suture Zone. Igneous rocks of the MVPC, consist of volcanic lavas and pyrclastic rocks, are andesitic basalt, diabase, microgabbro and dacite that were intruded by the late cretaceous granitoids. The volcanic rocks have characteristics of the calc-alkaline to tholeiitic magmatic series. The spider patterns normalized to N-MORB and Chondrite is similar to the ones belong to the supra-subduction zone (SSZ) and Islanc arcs ( IAT). The EPMA studies on the key minerals in volcanic rocks such as clinopyroxene , brought the same results. The pribable presence of an island-arc chain in the Sistan Suture Zone, which some of its parts are considered here as the MVPC, is comparable to continuation of the pakistanian Chagai-Raskoh and Kuhistan Cretaceous-Eocene island-arc/s in east. Considering this reality, we must expect to have a larger ocean much wider than what was already proposed for the Sistan Ocean as a narrow oceanic seaway in Continental rifting setting.
Economic Geology
Zahra Kaboodi; Majid Ghaderi; Ebrahim Rastad
Abstract
The Kahak copper deposit occurs in the Eocene volcano-sedimentary sequence of Qom region, Urumieh-Dokhtar magmatic arc. The oldest rock unit in this sequence is a crystal tuff, overlain by tuff, andesite, sandstone, conglomerate, and limestone. Host rocks to the Kahak deposit include andesite and tuff, ...
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The Kahak copper deposit occurs in the Eocene volcano-sedimentary sequence of Qom region, Urumieh-Dokhtar magmatic arc. The oldest rock unit in this sequence is a crystal tuff, overlain by tuff, andesite, sandstone, conglomerate, and limestone. Host rocks to the Kahak deposit include andesite and tuff, and the geometry of mineralization is stratabound. Mineralographical studies show that the ore minerals are pyrite, chalcopyrite, chalcocite, native copper, bornite, galena, covellite, digenite, and malachite accompanied by magnetite, and hematite. Based on mineralogical studies, two types of alteration are recognized in the volcanic rocks of the area, general alteration, and ore mineral alteration. The propylitic alteration is an indication of general alteration. The main alteration types in the mineralized zone of the deposit include carbonatization, silicification, chloritization, epidotization, and zeolitic. Dissemination, open space filling, vein-veinlet, pseudo-lamination, and replacement are the major textures and structures of the ore minerals at Kahak. Two major stages are distinguished for mineralization at the Kahak deposit. The first stage is volcanism and pyrite formation in the host rocks (andesite and tuff), producing reduction state. The second stage involves diagenesis and entering Cu-rich oxidant fluids replacing Cu for Fe in the pyrite and forming Cu-sulfides and hematite and mineralization. The Kahak copper deposit shows high similarities in geometry, host rock, mineralogy, texture and structure and genetic model with the Manto-type copper deposits worldwide.
Economic Geology
Hossein Abasnia; M. H. Karimpour; Azadeh Malekzadeh Shafaroudi
Abstract
Damanghor area is located northern Bardaskan, Khorasan Razavi province, and structurally, it is a part of Taknar zone. Geology of the area includes of Taknar metamorphosed sedimentary rocks and metarhyolite, which is intruded by diabasic rocks as stoke and dyke. The texture of metarhyolies is porphyry ...
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Damanghor area is located northern Bardaskan, Khorasan Razavi province, and structurally, it is a part of Taknar zone. Geology of the area includes of Taknar metamorphosed sedimentary rocks and metarhyolite, which is intruded by diabasic rocks as stoke and dyke. The texture of metarhyolies is porphyry and contains of quartz and feldspar, whereas diabas has ophitic texture and contain plagioclas, pyroxene, and hornblend. Age of metarhyolite and diabas determined 550 Ma (Neoprotrozoic) and 8.8 Ma (Miocene), respectively, using zircon U-Pb method. Metarhyolites have peraluminous nature and were formed at intracontinental rift. Low enrichment in LREE relative to HREE and Eu negative anomaly indicates the magma is formed at plagioclase stability depth. (87Sr/86Sr)i (0.700712), (143Nd/144Nd)i (0.511852), and εNdi (–1.51) values show source of magma was mantel or lower crust. Diabases have toleitic to metaaluminous nature and were formed at subduction zone. (87Sr/86Sr)i (0.710527), (143Nd/144Nd)i (0.512716), and εNdi (+1.7) values indicate magma is drived from partial melting of metasomatized mantle wedge by released fluid of subducted slab, which is assimilated with continental crust. Taknar formation acidic Neoprotrozoic magmatism, which is formed at rift setting, associated with Miocene basic magmatism, which is formed at subduction zone, reveals an insight of tectonomagmatic conditions of Taknar zone in different times.
Economic Geology
Rahimzadeh Bahman; M. Movahednia
Abstract
The Kamyaran manganese is located in the 20 km from NW of Kamyaran and south of Kurdistan province. In geological structure map these Mn-deposite are outcrops in Zagros and northern Sanandaj-Sirjan collision zone and close to Zagros ophiolites. In this area, Mn-mineralization occurs as regular lenses ...
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The Kamyaran manganese is located in the 20 km from NW of Kamyaran and south of Kurdistan province. In geological structure map these Mn-deposite are outcrops in Zagros and northern Sanandaj-Sirjan collision zone and close to Zagros ophiolites. In this area, Mn-mineralization occurs as regular lenses and interlayers with radiolarian cherts within the Eocene radiolarite and shale. The present work has been done based on field geology, mineralogy and geochemistry characterization. Study of Mineralogy and texturally Kamyaran Mn-ores show two stage mineralization including Braunite and Okhotskite were formed singenetic and pyrolusite was formed diagenetic. The high rate of Si and rhadiolarite fossils in Mn-bearing cherts suggest that the Kamyaran Mn-deposit was formed in deep oceanic area. The Variable content of Mn/Fe and high rate of detector element such as Ba and Sr revel the hydrothermal source for mineralization. Despite, Existence rhadiolarite fossils, sub-bedding deposits and some geochemical characterization suggest the sedimentary origin for Kamyaran Mn-deposit.
Economic Geology
Simindokht Younesi; Mohammadreza Hosseinzadeh; Mohsen Moayyed
Abstract
Mineralogy of oxide zone as clue about past climate reveals occurrence of supergene enrichment processes in Mahour Zn-Cu-(Pb-Bi-Ag) mineralization, in central Lut, during two stages: In first stage that supergene processes have occurred from meteoric waters in an arid climate during Oligocene to Upper ...
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Mineralogy of oxide zone as clue about past climate reveals occurrence of supergene enrichment processes in Mahour Zn-Cu-(Pb-Bi-Ag) mineralization, in central Lut, during two stages: In first stage that supergene processes have occurred from meteoric waters in an arid climate during Oligocene to Upper Miocene, leached capping contains jarosite, natrojarosite and goetite in various ratios and less hematite and sulfur has formed with supergene argillic alteration with quartz, alunite, kaolinite, montmorilonite, and gypsum. In response to neutrialization of solutions, an abundance of smithsonite and malachite with neotocite, greenokite /hawleite and minor azurite and silicate, phosphate and arsenate minerals precipitated in oxide zone and immature sulfide enrichment generated. In second stage, atachamite, paratacamite and chrysocolla have been formed through the interaction of saline waters and preexisting copper oxides after the onset of hyperaridity at Pliocene, and have been preserved since that time. Mineralogy features of leached capping provide insighs into hypogene ore mineral and alteration types and indicate sufficient acid has not been produced for effective leaching of Cu and hence, do not suggest extensive chalcocite enrichment under water table. An interpretation that mineralogy of oxide zone is also illustrative of it and results from exploration drill holes confirm it. With respect to style of Mahour polymetal mineralization and similar mineralizations in district, detail investigation of oxide zone and mapping leached caps in deposit and district scale can be used as suitable exploration tool in the search for conceal ore 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.
Economic Geology
Meysam Nikfarjam; Ardeshir Hezarkhani; Kaveh Pazand
Abstract
The study area (Varzaghan 1:100,000 Sheet) is located in eastern Azarbaijan province and Ahar-Arasbaran metallogenic zone. The magmatism in this area is happened widespreadly that leads to several important deposits like Sungun world class deposit. According to the importance of this region from Cu-Mo ...
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The study area (Varzaghan 1:100,000 Sheet) is located in eastern Azarbaijan province and Ahar-Arasbaran metallogenic zone. The magmatism in this area is happened widespreadly that leads to several important deposits like Sungun world class deposit. According to the importance of this region from Cu-Mo porphyry deposits, we used structural methods like multifractal method to determinate Cu and Mo geochemical anomalies as indicator minerals of Cu-Mo porphyry deposits. In this paper two multifractal method like C-A (Concentration-Area) and N-S (Number-Size) method were used in order to separation geochemical anomalies from background and select the optimum method. In this way, first of all, we draw catchment basins for every stream sedimentary samples by using DEM and PFS (Priority-First-Search) algorithm. After drawing the catchment basins for each sample, concentrations of samples were assigned to their upstreams. In C-A method with plotting cumulative area of each sample catchment basin versus concentration content, 4 number society of each Cu and Mo elements identified. Also in N-S method, cumulative frequency of concentrations versus concentrations plotted. In this method in comparison to C-A method, 5 number society of Mo and 4 number society detected. In both performed methods can see good conformity of anomalous locations with well known deposits like Sungun worldclass deposit but N-S method has better efficiency by using logratio matrix. Also we can see the effect of lithology in anomalous places. Finally some of theses places addition to indications detected. So they require detailed exploration in future.
Economic Geology
Fattaneh Pourmohammad; Hossein Kouhestani; Amir Morteza Azimzadeh; Ghasem Nabatian; Mir Ali Asghar Mokhtari
Abstract
Mianaj Fe ore occurrence is located in the Takab-Angouran-Takht-e-Soleyman metallogenic zone, 100 km southwest of Zanjan. In this area, Fe mineralization occurs as lens-shaped bodies parallel to the foliation of schist and rhyolitic meta-tuff units (equal to Kahar Formation). Based on mineralography, ...
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Mianaj Fe ore occurrence is located in the Takab-Angouran-Takht-e-Soleyman metallogenic zone, 100 km southwest of Zanjan. In this area, Fe mineralization occurs as lens-shaped bodies parallel to the foliation of schist and rhyolitic meta-tuff units (equal to Kahar Formation). Based on mineralography, ore mineral is magnetite, and quartz present as gangue mineral at Mianaj. The ore minerals show disseminated, laminated, banded, massive, vein-veinlet and replacement textures. Three stages of mineralization can be distinguished at Mianaj. The first stage is recognized as stratiform and stratabound lenses, laminated and disseminated crystals of magnetite parallet to the foliation of host rocks. Stage-2 mineralization is recognized by folding of ore bands, σ microfabric and boudinage of magnetite crystals, quartz pressure shadows and surrounding of foliation around magnetite crystals, and recrystallization of quartz and magnetite crystals. Stage-3 is recognized by quartz vein-veinlets that cut previous mineralization stages. Chondrite-nonmineralized REE pattern of host rocks and the mineralized samples indicate that mineralized samples are depleted in REE. This signature indicates mobility of REE by Cl and F-rich oxidized fluids during mineralization processes. Characteristics of Mianaj occurrence are comparable with metamorphosed and deformed volcano-sedimentary type of iron deposits.
Economic Geology
seyran yousefi; masoud alipourasl
Abstract
The Zarandieh district is situated approximately 42 km northeast Saveh (Markazi province) and in the northwestern part of the Urumieh-Dokhtar magmatic belt. In this area, mineralization is hosted by Eocene andesitic lava and Oligo-Miocene diorite and gabbroic rocks. According to the geochemical evidence, ...
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The Zarandieh district is situated approximately 42 km northeast Saveh (Markazi province) and in the northwestern part of the Urumieh-Dokhtar magmatic belt. In this area, mineralization is hosted by Eocene andesitic lava and Oligo-Miocene diorite and gabbroic rocks. According to the geochemical evidence, parental magma of igneous rocks is calc-alkaline, metaluminous and related to continental margin volcanic arcs. Mineralization has been observed as veins, veinlets and brecciated forms in diorite and gabbroic rocks. The main ore mineral is chalcopyrite and associated with pyrite, bornite, oligist, chalcocite, covellite, neotosit, native copper, malachite, azurite, chrysocolla, goethite and limonite. Cu grade in the ore samples are varied from 0.04 to 1.7 % (0.40 % in average). Statistical analyses of geochemical data from mineralized samples by Pearson method displayed that Cu has maximum correlation with Ag, As, Zn, Cd and Pb, respectively. Microthermometry studies of fluid inclusions show that the average homogenization temperature is 195° C and the average salinity of 23 wt% NaCl. The Zarandieh Copper mineralization is closely related to hydrothermal vein copper deposit types.
Economic Geology
mohammad maanijou; Azadeh Mirzai
Abstract
Bagher Abad and Darreh Badam fluorite mineralizations are located in southeast Mahallat city (Markazi province) and occured as veins with common trend of East-West within slate and phyllite of Shemshak Formation (Lower Jurassic). The fluorite is the main mineral of the veins and quartz, barite, calcite, ...
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Bagher Abad and Darreh Badam fluorite mineralizations are located in southeast Mahallat city (Markazi province) and occured as veins with common trend of East-West within slate and phyllite of Shemshak Formation (Lower Jurassic). The fluorite is the main mineral of the veins and quartz, barite, calcite, dolomite, pyrite, chalcopyrite, goethite and covellite are the sub-ordinary minerals of deposits. The distribution of rare earth elements (REE) indicates that the violet, colorless and gray fluorites in primary mineralization stage have been enriched in LREE (result of digestion and wall rock replacement) and and the blue types of fluorites enriched in MREE and HREE, formed in post mineralization stage. Tb/La vs Tb/Ca and Y/Ho ratios diagrams are used for determination of genesis and differentiation of fluorite mineralization. These data show all samples can have a hydrothermal source for Bagher Abad and Darreh Badam deposits. Negative anomaly of Eu in all samples of fluorite can be caused by the formation of fluorite at above 200°C temperatures. In addition to, depletion of Ce in fluorites of studied areas indicated a reduced fluid and presence of pyrite and chalcopyrite sulphide minerals confirming this.
Economic Geology
Pouria Mahmoodi; Ebrahim Rastad; Abdorrahman Rajabi; Mehran Moradpour
Abstract
The Early Cretaceous Eastern Haft-Savaran Zn-Pb (Ba) deposit situated in the Arak mining district and occurred within the extentional back-arc of Malayer-Esfahan basin. Mineralization occurred in two horizons in the Estern Haft-Savaran deposit. First horizon is major horizon that formed within the most ...
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The Early Cretaceous Eastern Haft-Savaran Zn-Pb (Ba) deposit situated in the Arak mining district and occurred within the extentional back-arc of Malayer-Esfahan basin. Mineralization occurred in two horizons in the Estern Haft-Savaran deposit. First horizon is major horizon that formed within the most upper portion of the massive limestone and second horizon occurred in the thin limestone which is alternate with shale and marl. Textures of the mineralization in this deposit are replacement, massive and vein- veinlets, and main alterations are silisification, dolomitization and calcitization. Sphalerite, galena, chalcopyrite, tetrahedryte, pyrite, bornite, chalcosite and covelite are the sulfide minerals and quartz, calcite, dolomite and sericite are gangue minerals in the ore deposit. Cathodoluminescence study in this deposit indicates three dolomites and one calcite generations. First generation of dolomite associated with weak mineralization and second generation of dolomite is Fe-rich and associated with main mineralization. Third generation of dolomite is late dolomitization and formed with calcite and cross-cutted the mineralization. Presence of framboidal pyrite with galena and sphalerite in its matrix and fine-grain euhedral barite suggest mineralization began during sedimentation and early diagenesis stage near seafloor. In continuum, main ore is identified as replacement occurrence of first generation sulfides by second generation coarse-grained sulfides under seafloor. With regarding to the formation of the Eastern Haft-Savaran deposit in the extentional tectonic setting, massive limestone as the host rock, and mineralization formation as replacment during diagenesis of the host rock under the seafloor, this deposit would be classified as Irish type deposit.
Economic Geology
Ghodratollah Rostami Paydar
Abstract
The Zarshuran gold deposit in northwest Iran is located in historic gold and arsenic mining area in the Sanandaj-Sirjan geo-structural zone. This area is mainly composed of Precambrian rocks. The Oligo-Miocene granitoid intrusions in Pre-Cambrian formations which are the country rocks of gold mineralization ...
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The Zarshuran gold deposit in northwest Iran is located in historic gold and arsenic mining area in the Sanandaj-Sirjan geo-structural zone. This area is mainly composed of Precambrian rocks. The Oligo-Miocene granitoid intrusions in Pre-Cambrian formations which are the country rocks of gold mineralization have resulted from intensive alteration, milonitization and gold mineralization. The main aim of these study is the separation of gold mineralization zones by using concentration-number (C-N) and concentration- volume(C-V) fractal techniques, which is based on 44 drill hole data and 5800 analyzed samples. Firstly, the logarithmic graph of gold was plotted for each model. Five gold mineralization zones were identified by using concentration-number model and four zones with concentration- volume model, indicate that intense of gold mineralization in wall rock, weak, medium, high and highly enriched zone, respectively. 3D geologic and fractal models show that low mineralized zones occurred in most of the ore deposits, which are often related to the Iman-Khan rock unit. In addition, based on fractal model interpretations and calculation of the overall accuracy matrices, these regions with medium, high and enriched zone have good overlaps to the Jasperoid rock unit, Chaldagh limestone, and Zarshuran shale units, respectively.
Economic Geology
Hossein Kouhestani; Mir Ali Asghar Mokhtari
Abstract
Tashvir ore occurrence, 75 km northeast of Zanjan, is located in the Tarom-Hashtjin subzone. Mineralization occurs as ore-bearing quartz vein-veinlets within the Eocene tuffs and andesitic lavas (equal to Karaj Formation). Ore minerals include chalcocite, chalcopyrite and galena, and quartz, calcite ...
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Tashvir ore occurrence, 75 km northeast of Zanjan, is located in the Tarom-Hashtjin subzone. Mineralization occurs as ore-bearing quartz vein-veinlets within the Eocene tuffs and andesitic lavas (equal to Karaj Formation). Ore minerals include chalcocite, chalcopyrite and galena, and quartz, calcite and chlorite are present as gangue minerals at Tashvir. The ore show vein-veinlets, breccia, disseminated, replacement, relict, colloform, crustiform, dog tooth and plumose textures. Four stages of mineralization can be distinguished at Tashvir. These stages are progressed from quartz- chalcocite- chalcopyrite- galena‒cemented veins and breccias (stage-1), individual or sets of quartz veinlets (stage-2), and vug infill calcite (stage-3) and chlorite (stage-4) vein-veinlets. Hydrothermal alteration consist of silicified, argillic, carbonatic and chloritic. In the outer parts of the mineralization zones, alteration is propylitic. Similar REE patterns of the mineralized veins and the host rocks indicate they are genetically related. Enrichment of ore-forming elements (Ag, Cu, Pb, Zn) in ore zones is specifies leaching of elements from altered host rocks to ore zones. Characteristics of Tashvir ore occurrence are comparable with intermediate-sulfidation style of epithermal base metal (Ag) deposits. Mineralization at Tashvir and other epithermal deposits of the Tarom-Hashtjin subzone took place as a result of hydrothermal activity related to the late Eocene magmatism, and is controlled by fault systems. Therefore, investigation of the altered Eocene volcanic and volcano-sedimentary rocks, especially at the composite place of granitoid intrusions and along the fault structures, became the most favorable locus for epithermal ore bodies at Tarom-Hashtjin subzone.
Economic Geology
shirin fatahi; Ahmad Jahangiri; Farhad Maleckqasemi; seyedhasan tabatabaei
Abstract
Abstract Qezelbalaq Arsenic ore deposite is located in Hashtrud, 120 km from southeast of Tabriz. In this district effect of dacitic Sahand domes on sandy limestones and Qom formation sandstone with Oligomiocene age and pyroclacitic units with Miocene age leads to formation of various types of alteration ...
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Abstract Qezelbalaq Arsenic ore deposite is located in Hashtrud, 120 km from southeast of Tabriz. In this district effect of dacitic Sahand domes on sandy limestones and Qom formation sandstone with Oligomiocene age and pyroclacitic units with Miocene age leads to formation of various types of alteration such as Silicic, phyllic, intermediate argillic, advanced argillic and dolomitization. It seems that Arsenic mineralization has occurred in two main step: 1) Pyrite± Chalcopyrite± Arsenopyrite that are consistent with phyllic zone. Fluide responsible mineralization have high temperature (nearly 250 centigrade degree) and fs2 between 10-15 to 10-20 and 2) Pyrite± Native arsenic± Realgar± Orpiment± Galena± Stibnite wich are consist with intermediate argillic and advanced argillic zones. Hydrothermal fluid in this stage has lower temperature (nearly between 180 to 210 centigrade degree) with fs2 between 10-7.8 to 10-13. These assemblage are associated with hematite, diaspore, kaolinite, alunite and arsenolite. Average of arsenic grade in phylilc zone is 655 ppm and in argillic zone is 11930 ppm. Mass change calculation indicate enrichment in many metals such as As, Sb, Hg, Ag and Au. According to geochemical studies, As, Hg and Sb are pathfinder for probebly Porphyry copper mineralization and gold in study area.
Economic Geology
Reza Ghezelbash; A. Maghsoudi
Abstract
Varzaghan district is located in NW of Arasbaran magmatic belt (AMB) which is one of the most highly mineralized region in Iran and host to a significant number of porphyry Cu deposits such as Sungun Cu-Mo porphyry deposit. The main goal of this study is synthesizing diverse raster-based evidence layers ...
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Varzaghan district is located in NW of Arasbaran magmatic belt (AMB) which is one of the most highly mineralized region in Iran and host to a significant number of porphyry Cu deposits such as Sungun Cu-Mo porphyry deposit. The main goal of this study is synthesizing diverse raster-based evidence layers including geochemical, alteration and geological geo-data sets for mineral prospectivity modeling (MPM). For this purpose, firstly, continuous values of six favorable evidential maps as main criteria (geochemical signature of PC1 scores, values of proximity to argillic, phyllic and iron-oxide alterations, values of proximity to Oligo-Miocene intrusions and fault density) were divided into reasonable classes by applying concentration-area fractal model and then discretized layers were integrated using analytical hierarchy process (AHP) and technique for order preference by similarity to ideal solution (TOPSIS) to generate a final map of porphyry Cu potential within the central part of Varzaghan district. Finally, the success-rate curve of the AHP-TOPSIS model as a quantitative evaluation method according to the locations of known Cu occurrences was drawn. Results revealed the successful performance of AHP-TOPSIS model in portraying the prospective areas related to porphyry Cu mineralization.
Economic Geology
S. Maleki; A. A. Calagari; K. Siahcheshm; S. Alirezaei
Abstract
Khak Sorkh iron deposit located about 42 km northwest of Nadushan town in Yazd Province. Host rock include upper Triassic-Jurassic limestone which are intruded by Oligo-Miocene granitoid bodies. Mineralization is dominated by magnetite, and serpentine is the main waste mineral. Skarn mineral assemblages ...
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Khak Sorkh iron deposit located about 42 km northwest of Nadushan town in Yazd Province. Host rock include upper Triassic-Jurassic limestone which are intruded by Oligo-Miocene granitoid bodies. Mineralization is dominated by magnetite, and serpentine is the main waste mineral. Skarn mineral assemblages include clinopyroxene, garnet, tremolite phlogopite and epidote. The characteristics of mineralization are: magnetite mineralization in two generations, presence of serpentine as the main waste mineral, hornfelsed greywacke units which come between intrusive bodies and skarned limestone units, absence of obvious zoning in endoskarn and exoskarn parts, presence of Ni-Co-As sulfides, high amount of Zn, As, Co and Mn in magnetite geochemical results and the increasing Fe along with decreasing Mg contents in magnetite at both deposit and crystal scales from primary to secondary types. Minor elements contents of geochemical results have been used for distinguishing of different mineral deposits (e.g, Dare et al., 2012; Dupuis and Beaudoin, 2011; Nadoll et al., 2012) and they are in good accordance to hydrothermal and skarn type deposits like: low contents of Cr (less than 10 ppm), high contents of Mg (2.2 to 7.5 ppm), low TiO2 (from 0.01 to 0.3 ppm), low amounts of incompatible elements including Ag (
Economic Geology
Mitra Eftekhari; Mohammad reza Hosseinzadeh; Mohsen Moayyed
Abstract
The Studied area is located in vicinity of the Sherbit village, about 28 km to the northwest of Ahar (in Eastern Azerbaijan province. Quartz monzonite intrusion is the host rock of hydrothermal tourmaline in this area. On the basis of their textural features, the tourmalines can be divided into four ...
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The Studied area is located in vicinity of the Sherbit village, about 28 km to the northwest of Ahar (in Eastern Azerbaijan province. Quartz monzonite intrusion is the host rock of hydrothermal tourmaline in this area. On the basis of their textural features, the tourmalines can be divided into four groups: 1) tourmaline veins, 2) tourmaline-breccias, 3) massive tourmaline and 4) pore space filling tourmaline. Based on the petrography and electron microprobe analysis studies, tourmalines of Sherbit area are correspond to intermediate schorl-dravite with more tendencies toward dravite composition and have been formed in hydrothermal conditions. According to reasons such as more Mg values compared to Fe, low Al amounts, fine scale zoning, content of fluorine, tendency toward outer side of alkali- and proton-deficient vectors and lack of negative correlation between Fe and Mg. Separated tourmaline from the quartz– tourmaline vein shows a very similar pattern to the quartz monzonite samples, which are characterised by a pattern with depletion in HREEs relative to LREEs. It can be concluded that REE concentrations and patterns of tourmaline from the different studied tourmaline rocks are controlled by the host rock and not by the hydrothermal fluid causing boron metasomatism.
Economic Geology
Hossein Ali Tajeddin; S Hassankhanlou; Mohammad Mohajjel
Abstract
Abdossamadi barite deposit is located 80 km northeast of the city of Marivan in the northwestern part of the Sanandaj–Sirjan metamorphic zone. The rocks in the deposit area predominantly consist of Cretaceous volcanosedimentary sequences of metamorphosed andesite, calcareous shale and limestone, ...
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Abdossamadi barite deposit is located 80 km northeast of the city of Marivan in the northwestern part of the Sanandaj–Sirjan metamorphic zone. The rocks in the deposit area predominantly consist of Cretaceous volcanosedimentary sequences of metamorphosed andesite, calcareous shale and limestone, metamorphosed under greenschist facies grade. The deposit is composed of stratiform ore and stringer zone. The stratiform ore consists of a lens-like barite body associated with sulfide minerals which are underlain by metamorphosed (and altered) andesite (stringer zone) and was under the calcareous shale. Sulfide mineral assemblages of the deposit are simple and consist of pyrite, sphalerite, galena, chalcopyrite, and tetrahedrite-tennantite. Massive, bedded, colloform, framboidal and disseminated structures and textures are common in the stratiform ore and indicate deposition of the deposit on the sea floor. The stringer zone that forming footwall of the stratiform ore is altered andesite that cut by sulfide-bearing quartz-barite veins and veinlets. Fluid inclusion studies indicated that barite samples in the stratiform ore homogenized between 115° and 215°C. Salinities of the fluid inclusions show a range from 0.21 to 5.86 wt.% NaCl equivalent. Cooling of the ore-bearing hydrothermal fluid is an important process in the stratiform ore deposition. This study shows that the barite deposit is an immature Kuroko type massive sulfide deposit, which contains only black ore. The deposit underwent metamorphism and deformation after the ore deposition and therefore, shows significant changes in ore structures and textures.
Economic Geology
Hakima Taghadosi; Azadeh Malekzadeh Shafaroudi
Abstract
Namegh area is located northeastern Kashmar, Khorasan Razavi province, and centeral part of of Khaf-Kashmar-Bardaskan magmatic belt. Geology of the araea is covered by Eocene volcanic rocks having andesite to rhyolite composition, which are intruded by subvolcanic intrusions with monzonite, monzodiorite, ...
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Namegh area is located northeastern Kashmar, Khorasan Razavi province, and centeral part of of Khaf-Kashmar-Bardaskan magmatic belt. Geology of the araea is covered by Eocene volcanic rocks having andesite to rhyolite composition, which are intruded by subvolcanic intrusions with monzonite, monzodiorite, and diorite composition. All of units are affected by well development alteration, which are silicified-sericitic, moderate argillic, and propylitic alteration zones. Mineralization is occurred as stockworck and disseminated. Primary minerals include chalcopyrite, pyrite, magnetite, and gold and secondary minerals include goethite, hematite, malachite, and azurite. High anomaly of Cu (up to 1%) and Au (up to 12 ppm) are correlated with strong silicified-sericitic alteration. Based on fluid inclusion studies, formation temperature of mineralization is between 404 to 551 ºC and it is occurred from NaCl-, and CaCl2-bearing fluid with 15 to 23 wt. % NaCl equivalent salinity. Decrease of temperature and HCl activity during boiling time and decrease of temperature due to mixing of magmatic and meteoric fluids could be the most important factors for formation of mineralization. Evidences of tectonic setting, lithology, development and types of alteration, mineralization form and limited outcrops, types of ore minerals, geochemical anomalies, types of fluid inclusions and temperature and salinity of fluid indicate the mineralization of Namegh is probably upper level of porphyry Cu-Au deposit. The Khaf-Kashmar-Bardaskan belt can be one of the most important porphyry deposits metallogenic zones of Iran due to tectonic setting and magmatic-mineralization evidences, which needs detailed exploration in future.
Economic Geology
Mahin Zolfaghari; Ghasem Nabatian; Amir Morteza AzimZadeh; Maryam Honarmand; P. Azizi
Abstract
Pirgheshlagh Cu-Zn-Pb deposit is located in the Central Iranian zone, north-east of the Mahneshan in the Zanjan province. The Kahar Formation with Precambrian age is the oldest Formation in the area which cutted by the granitic dykes. The Pirgheshlagh Cu-Zn-Pb mineralization occurred mainly as tabular-shape ...
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Pirgheshlagh Cu-Zn-Pb deposit is located in the Central Iranian zone, north-east of the Mahneshan in the Zanjan province. The Kahar Formation with Precambrian age is the oldest Formation in the area which cutted by the granitic dykes. The Pirgheshlagh Cu-Zn-Pb mineralization occurred mainly as tabular-shape within the metamorphosed sandstones, meta-andesitic tuff, meta-crystal lithic tuff and meta-andesite rocks. Based on the field and microscopic studies, the main minerals consist of chalcopyrite, sphalerite, galena, pyrite, arsenopyrite and minor magnetite. The ore textures consist of disseminated, laminated, massive and veinlet which the veinlet texture is occurred mainly in the lower part of deposit. Secondary minerals such as smithsonite, cerrusite, chalcocite, covellite, malachite, azurite, goethite and lepidochrosite have formed during supergene processes. The main alterations in the Pirgheshlagh deposit include silicic, sericitic, chlorite and carbonate. The results of this study suggest that the Cu-Zn-Pb mineralization in the Pirgheshlagh deposit is a Besshi-type valcogenic massive sulfide (VMS) mineralization.
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.
