Economic Geology
Fatemeh Esmaeili; Fardin mousivand; Mahmoud Sadeghian; Seyed Mehran Heidari
Abstract
Miandasht copper deposit is located in 110 km east of Shahrood, 24km north west of Abbasabad, and in the Cenozoic volcanic belt of north of Central Iran zone. The major rock units of the study area have Eocene age and include submarine flows (andesite, basalt, and trachyandesit), pyroclastic (tuff breccia ...
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Miandasht copper deposit is located in 110 km east of Shahrood, 24km north west of Abbasabad, and in the Cenozoic volcanic belt of north of Central Iran zone. The major rock units of the study area have Eocene age and include submarine flows (andesite, basalt, and trachyandesit), pyroclastic (tuff breccia and agglomerate) and sedimentary complex (Nomullitic limestone, tuffacous limestone, shale, sandstone and conglomerate). Mineralization in the Miandasht copper deposit occurred as parallel to layering of the host rocks (tuff breccia and agglomerate), and also along with cross- cutting faults of the host rocks in form of stratabound and epigenetic ores. The main ore textures include vein- veinlets, open space filling, disseminated and replacement. The Ores contain primary pyrite, chalcopyrite, chalcocite, bornit, and secondary covellite, chalcocite, malachite, hematite and limonite. The most important wall rock alterations accompanied with mineralization are carbonatic- silicic, sericitic, argillic, and chloritic, and that the amound of carbonatization and silicification increases with closing to mineralization zones. According to geochemical studies, tectonic setting of the deposit was extensional environment formed in a continental margin volcanic arc. Based on essential characteristics of the copper mineralization such as tectonic setting, host rocks, mineralogy, and type of alterations, the Miandasht copper deposit shows many similarities with Manto- type deposits, dominantly formed during orogeny, folding and faulting of the host sequence. It should be mentiond that some charachteristic features of the Miandasht copper deposit including development of argillic alteration, and lack of extensive zeolitic alteration, distinguishes it from other copper deposits in the region including Abbasabad deposit.
Tectonics
Zahra Mohammadyasl; Abdollah Saidi; Mehran Arian; Ali Solgi; taher Farhadinejud
Abstract
The Studied area is located in the small part of the structural zone of Urumieh- Dokhtar Magmatic Arc, at 60km far from south of Qom and 12km far from south east of Kahak. In the beginning, 1:25000 map of the area was prepared, because, region is located in two 1:100000 scale map sheet of Kahak and Aran, ...
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The Studied area is located in the small part of the structural zone of Urumieh- Dokhtar Magmatic Arc, at 60km far from south of Qom and 12km far from south east of Kahak. In the beginning, 1:25000 map of the area was prepared, because, region is located in two 1:100000 scale map sheet of Kahak and Aran, and more rock units were separated. In the next step, in a several step of the field observations, 17 samples of regional volcanic rocks were taken for XRF and ICP chemical analysis, and they main Oxides, heavy metals and rare elements were identife. Most of the samples have been located in the Calk- alkaline series, and some in the Tulleit series. In the lithology diagrams, these samples respectively are arranged in the range of Andesite, Dacite, Trachy Andesite and Rhyolite Rocks. Due to the anomalies and the amount of Nb in the samples of the region, they formation can be related to the subduction zone. On the other hand, the depletion of Nb and Ti is special in magmatism in the subduction zone. Because in the subduction regions released fluids from floating lithospheric rich in LILE, increases in the mantle wedge. Since in the study area rocks exhibit calc- alkaline with moderate to high potassium, it can be concluded that the stones are related to active continental margin associated with subduction.
Economic Geology
yegane khoramtash; farajolah fardoost
Abstract
The Saghari copper deposit is located 120 Km at Southwest of shahrood, within in the eastern part of Toroud-Chahshirin magmatic arc. Mineralization in the Saghari area occured within volcanic and pyroclastic units of Eocene. Based on the field, laboratory investigations and geochemical analysis, the ...
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The Saghari copper deposit is located 120 Km at Southwest of shahrood, within in the eastern part of Toroud-Chahshirin magmatic arc. Mineralization in the Saghari area occured within volcanic and pyroclastic units of Eocene. Based on the field, laboratory investigations and geochemical analysis, the outcropped rocks in the Saghari deposit are andesite, andesite-basalt, basalt, dacite and several exposures of pyroclastic rocks such as tuff and agglomerate. The rocks are high-k, calc-alkaline to a small amount of shoshonitic in nature, and are formed at a magmatic arc setting in a subduction zone. Basic to intermediate dyke bodies intruded Eocene volcanic-pyroclastic sequences. The host rocks have been affected by argillitic, sericitization, chloritzation, carbonatization and oxide-Fe (limonite, hematite and goethite). The textures and structures of mineralization are vein-veinlet, replacement, open space filling and disminated. According to the mineralography studies, main minerals of copper are malachite, chalcocite, covellite, chalcopyrite, chrysocolla and rare native copper. Malachite and chalcosite are the most abundant minerals. Geochemical studies indicate that copper has a relative correlation with silver.also based on studies of fluid inclusion, the depth of the ore, formation temperature and salinity are 100-200 meter, 100-140 °c and 5-15 WtNaCl%. Copper mineralization in the Saghari deposite has similarities in mineralogy, host rock, texture, structure and geometry with manto-type and volcanic red bed copper deposits.
B Hajalilou; Z Karimzadeh; M Advai
Abstract
The properties and situation of copper mineralization in the Haj Alibay Kandi area determined by quartz vein fluid inclusion and geophysical explorations in this study. The most important rock units include Oligocene intrusive rocks with monzonite and quartzmonzonite compositions. These rocks belong ...
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The properties and situation of copper mineralization in the Haj Alibay Kandi area determined by quartz vein fluid inclusion and geophysical explorations in this study. The most important rock units include Oligocene intrusive rocks with monzonite and quartzmonzonite compositions. These rocks belong to calc-alkaline series and post orogenic and post collision regimes. The mineralization in this area was controlled by faults with NE-SW direction. These mineralizations are related to the Sheivar-Dagh and younger intrusives. Chalcopyrite, pyrite, chalcocite, digenite, covelite, malachite, bornite and iron oxides were determined by mineralographical studies. On the basis of geophysical explorations, the chargebility anomaly at the depth of 40 to 50 meters is related to the concentration of sulphide minerals. This anomaly is conforms with faulting system in the area. The salinity of ore bearing fluid is from 5 to 50 wt% of NaCl and the homogenization temperature is 200 to 2400c and higher, on the basis of fluid inclusions studies. Fluid inclusions data are conformable with porphyry and epithermal copper deposits. This study shows that the boiling of ore fluids occurred at the mineralization stage. The shape of copper mineralization is vein and veinlets in this area and similar to cordilleran vein type deposit which can be observed at the top of porphyry copper deposits . Therefore, the formation of porphyry copper deposit at the deep levels of this area is expected.
V. Alizadeh; M. Momenzadeh; M. H. Emami
Abstract
Based on Qayen 1:100000 geological map, the copper mineralization of Vorezg in volcanic rocks is attributed to Paleocene-Lower Eocene. Submarine volcanic rocks of the study area are found in two forms of lava and pyroclastics. Based on field and laboratory investigations, the outcropped rocks in Vorezg ...
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Based on Qayen 1:100000 geological map, the copper mineralization of Vorezg in volcanic rocks is attributed to Paleocene-Lower Eocene. Submarine volcanic rocks of the study area are found in two forms of lava and pyroclastics. Based on field and laboratory investigations, the outcropped rocks in Vorezg deposit are andesite, andesite – basalt, basalt and several small exposures of pyroclastic rocks such as tuff. Alkaline volcanic rocks of the area show within plate characteristics. Texture of mineralization is vein-veinlet, disseminated and open space filling amygdales. According to the mineralography studies, main minerals of copper are chalcocite, β-chalcocite, bornite, covellite, digenite and rare native copper. Chalcocite is the most abundant mineral. Intergrowth among copper ores is observed in most cases. Silver was detected as accessory phase (copper element paragenesis) in this ore deposit. Whereas silver has not founded an independent crystalline phase, therefore in the crystal of chalcocite, copper was replaced by Ag. Fluid inclusion studies on trapped fluids in quartz show homogenization temperature average is 230-250 ºC and salinity degree of fluids is 5-6%wt NaCl. On the basis of recognized characteristics, Vorezg ore deposit is comparable with Manto and Volcanic redbed type copper deposits. Recently, these two types of deposits are considered as synonyms.
M. Mohamadian; M. Boomeri; A. Ahmadi; A. A. Moridi Farimani; H. Daglas; M. Jamali
Abstract
Sungun Porphyry Copper Deposit is located about 130 km to the northeast of Tabriz, northeast Iran. This deposit contains 796 million tons of ore with 0.61% Cu, 0.01% Mo, 0.016 ppm Au, 9.75 ppm Bi and Re (0.09 wt% of molybdenite). This research studies the physico-chemical environment using the chemical ...
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Sungun Porphyry Copper Deposit is located about 130 km to the northeast of Tabriz, northeast Iran. This deposit contains 796 million tons of ore with 0.61% Cu, 0.01% Mo, 0.016 ppm Au, 9.75 ppm Bi and Re (0.09 wt% of molybdenite). This research studies the physico-chemical environment using the chemical properties of minerals of this deposit. This deposit is related to granodiorite-diorite dikes and granodiorite stock that intruded into sedimentary and volcanic rocks of Cretaceous and Eocene. Dominant alterations are potassic, phyllic, argillic and propylitic from center outward which are characteristics of continental margin porphyry copper deposits. Simultaneously with the supergene mineralization, an iron cap of iron oxides, iron hydroxides, copper oxides, sulfates, carbonates and copper phosphates were developed on top of the deposit and along the fractures. In conclusion, based on mineral chemistry, in 450 ºC and 0.5 kb pressure (PT condition of potassic zone), sulfur fugacity and pH is determined to be as: log¦S2=-18 to -24 an pH=2.5 to 7.5. In 350 ºC and 0.5 kb pressure (PT condition of phyllic zone), oxygen and sulfur fugacities are: logƒO2= -20 to -33 and log¦S2=-6 to -15.
M. Abdi; Majid Ghaderi; N. Rashidnejad-Omran; A. Najafi
Abstract
Two cases of tungsten-copper vein-type mineralization have been studied in the Nezam-abad and Deh-hossein areas, in southwest of Shazand. The hydrothermal quartz-tourmaline mineralized veins have different host rocks (biotitic-granite and meta-sandstone). Considering similar ore metals (tungsten-copper-tin-lead-zinc) ...
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Two cases of tungsten-copper vein-type mineralization have been studied in the Nezam-abad and Deh-hossein areas, in southwest of Shazand. The hydrothermal quartz-tourmaline mineralized veins have different host rocks (biotitic-granite and meta-sandstone). Considering similar ore metals (tungsten-copper-tin-lead-zinc) in the Nezam-abad and Deh-hossein areas, same mineralogy of veins (quartz-dravite) and similar REE variation patterns in the two areas, it is suggested that the Nezam-abad and Deh-hossein mineralized veins have the same origin. It means, when the Br-bearing fluids were active, they caused the quartz-tourmaline vein-type mineralization in this area. Considering the barren intrusions in the area and other mineralogical-geochemical evidences in this study, it could be concluded that tungsten and other metallic elements in the Nezam-abad and Deh-hossein ore-bearing veins have a sedimentary/metamorphic origin.
M. Maanijou; I. Rasa; D. Lentz
Abstract
Chehelkureh copper deposit is located in Kuh-e-Lunka area, 120 km NW of Zahedan (SE of Iran). The host rocks of mineralization are intercalated Eocene turbiditic greywackes, siltstones, and shales (flysch). They are folded with N-S trend and the eastern limb of this fold has ...
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Chehelkureh copper deposit is located in Kuh-e-Lunka area, 120 km NW of Zahedan (SE of Iran). The host rocks of mineralization are intercalated Eocene turbiditic greywackes, siltstones, and shales (flysch). They are folded with N-S trend and the eastern limb of this fold has been drag folded. Several stocks and dykes of granodiorite to quartz monzodiorite and granite compositions intruded the turbidites, converting them locally to hornfels. These intrusions are oriented parallel to the major NW-SE fault set. The Chehelkureh ore field comprises numerous irregular lenses and veins. The ore field extends for 1500m in N23°W direction, and is displaced by late brittle faults striking roughly E-W. The fault and fracture filling ores include quartz, dolomite, ankerite, siderite, calcite, and lesser amounts of pyrrhotite, arsenopyrite, pyrite, chalcopyrite, sphalerite, galena, Se-rich galena, marcasite, molybdenite, ilmenite, and rutile. Assay data from 39 drill holes show high contents of base metals, with an average of 1.48% Cu, 1.77% Zn, 0.85% Pb (4.1% Cu+Zn+Pb), and silver (average 22 ppm in 45 samples). The ores are not so enriched in gold (0.14 ppm on average in 45 samples).
A composite sample of least-altered greywackes and shales (host rocks) is used for comparison with mineralized samples. Mass-balance calculations were carried out to quantify chemical changes resulting from different alteration episodes. With the low solubility and low variance of Al (Al2O3) in moderately altered sedimentary country rocks compared with many other immobile trace components, Al2O3 is used as an immobile component for mass-balance calculations. There is a net mass increase in Fe2O3T, and MgO and a net mass decrease in Na2O, CaO, K2O, and SiO2 with chloritization. Carbonatization shows Fe2O3T, and MgO enrichment and SiO2 and Na2O depletion, implying that ankerite, siderite and dolomite are predominant phases. SiO2 is enriched in silicified samples and depleted in other alteration types. There is no mass change in Cu, Pb and Zn with kaolinization, but these elements are enriched in other alteration types. Hg is enriched in all alteration types except kaolinization, which may even show a slight depletion. Samples from gossan with silicification showed an increase in SiO2, Fe2O3T, Cu, Pb, Hg, and Zn and a decrease in MgO, Na2O, CaO, and K2O. Some trace and major elements have high variance in different alterations and are more complicated to interpret, such as P2O5, MnO, Ni, Co, and Rb.
The REE contents of the composite host rock sample are enriched in the LREE relative to the HREE and moderately depleted in Eu and Ho. As a whole, samples with kaolinization and carbonatization (ankerite and siderite) have been enriched in REE contents and other wallrock alteration, including chloritization, dolomitization, kaolinization, minor sericitization, and silicification, are depleted in REE. SEM-EDS evidence indicates that enrichment of REE-bearing phosphates, such as monazite, occurred with carbonatization and kaolinization assemblages.
