A Mohebi; A Hezarkhani; M Behzadi; H Mirnejad; H Taghi Zadeh
Abstract
Bondar Hanza porphyry copper deposit occurs 150 km southeast of Kerman, in southern part of the Urmia-Dokhtar zone and in Dehaj-Sardoiyeh zone. This ore deposit has formed in diorite to granodiorite rocks. The present paper deals with the study of fluid inclusion on quartz and hornblende samples as well ...
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Bondar Hanza porphyry copper deposit occurs 150 km southeast of Kerman, in southern part of the Urmia-Dokhtar zone and in Dehaj-Sardoiyeh zone. This ore deposit has formed in diorite to granodiorite rocks. The present paper deals with the study of fluid inclusion on quartz and hornblende samples as well as the measurement of isotopic ratio of oxygen and hydrogen with the aim to recognize characterization of hydrothermal fluids effective in mineralization. The studied veinlets are divided into five groups. Veinlet I: fluid of high pressure (>300 MPa) and medium to high temperature (250°C-300°C) with salinity of 38-45 Wt%NaCl that includes molybdenum mineralization. This veinlet contains halite and anhydrite and has resulted in potassic and sodic-calcic mineralization in deeper parts of the ore deposit. Veinlet II: high pressure (>300 MPa), high salinity (33-47 Wt%NaCl) and high temperature (250°C-420°C), containing copper and molybdenum mineralization as well as potassic alteration. Veinlet III: high salinity (40-56 Wt%NaCl), high pressure (>300 MPa) and high temperature (200°C-500°C), containing copper mineralization. Veinlet IV: medium to low salinity (6-7 Wt%NaCl), medium temperature (approximately 170°C), low pressure (0/7-0/8 MPa), containing no mineralization. The study performed indicate that the boiling occurred in the initial magma, as a result of pressure and temperature changes and mixing with meteoric waters, caused copper and molybdenum mineralization. Results obtained from oxygen and hydrogen isotopic analysis in quartz show δ18O to vary from 3.9 to 6.3 per mil. Considering its formation temperature and based on thermometric study (130-400°C), the amount of δ18o in mineralizing fluid is from 5.26 to 6.19 per mil, being indicative of magmatic origin of mineralization fluids like the other porphyry copper deposits of Iran and the world. While results of hydrogen analysis existed in fluid inclusions of quartz mineral illustrate a range between -88 to -90 per mil, being indicative of a decrease in the amount of mineralizing fluid deuterium. These values are traceable to the effect of meteoric waters, given the propylithic and sodic alterations accompanied with potassic alteration in mentioned veinlet.
M Lotfi; M Hekmatian; A.A Shabani; M.A Mokhtari
Abstract
Oras-kuh lead-zinc deposit is located at about 79 km north-east of Semnan city. This deposit is considered as stratabound and occurs in the upper part of the Triassic dolomitic limestone of the Elika formation. Oras-kuh structure includes a northeast - southwest trending normal anticline and follows ...
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Oras-kuh lead-zinc deposit is located at about 79 km north-east of Semnan city. This deposit is considered as stratabound and occurs in the upper part of the Triassic dolomitic limestone of the Elika formation. Oras-kuh structure includes a northeast - southwest trending normal anticline and follows the general trend of the eastern Alborz. Folding in the area has generatedthree sets of jointsincludingjoints trending parallel to the direction of anticline axis, extensional joints perpendicular to anticline axis and the conjugate joint systems. The first two setsof the joints host vein form mineralization. In addition, breccia and karst filling mineralization can be detected. Major minerals are galena, sphalerite and pyrite that altered to secondary minerals such as cerussite, goethite, hydrohetarolite and rosasite under the supergene processes. Gangue minerals are dolomite, calcite, barite, quartz, and small amounts of fluorite. The majority of the temperature data are between 298 to 323°C based on the fluid inclusion geothermometry of calcite and barite minerals. The relatively high temperatures of fluid inclusions are attributed most likely to a concealed deep intrusion in the crust inferred byairborne geomagnetic survey. Fluid salinities show a wide range from 0.6 to 15wt% equivalent weight of NaCl formed through mixing of basinal brines with meteoritic water. In general based on the present evidences, Oras-kuh lead-zinc deposit can be comparable with MVT deposits that its primary mineralogy and elemental ratios have been changed through secondary supergene processes.
H Mohammaddoost; M Ghaderi; N Rashidnejad-Omran
Abstract
Qamsar cobalt deposit is located 26 km south of Kashan, in the middle part of Urumieh-Dokhtar magmatic arc. Exposed rock units in the area include Eocene volcanics, Qom Formation marine sediments and plutonic bodies. The intrusive bodies have quartz-diorite to granodiorite composition as well as porphyry ...
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Qamsar cobalt deposit is located 26 km south of Kashan, in the middle part of Urumieh-Dokhtar magmatic arc. Exposed rock units in the area include Eocene volcanics, Qom Formation marine sediments and plutonic bodies. The intrusive bodies have quartz-diorite to granodiorite composition as well as porphyry microdiorite. Intruding bodies into the Eocene volcanics and Qom Formation units caused recrystallization and metamorphism and formed assemblages of skarn minerals such as garnet, pyroxene, epidote, tremolite and actinolite. Mineralization occurred as endo-skarn and exo-skarn in massive, vein, brecciated, open space filling and diffusion forms. Magnetite is the main ore mineral and is accompanied by cobaltite, chalcopyrite and pyrite. Fluid inclusion microthermometry studies were performed on prograde stage garnet and pyroxene and retrograde stage quartz. Microthermometry studies show homogenization temperatures from 400 to more than 600°C and from 180 to 200°C as well as salinities between 12 and 20% and between 5.8 and 11.9% wt NaCl equiv. for prograde and retrograde phases, respectively. Isotopic thermometry on pyrite-chalcopyrite pair minerals gives 241 to 528°C and that for quartz-magnetite pair minerals gives 441 to 549 °C. Sulfur and oxygen isotopic ratios offer magmatic origin which mixed with basinal fluid for this mineralization.
M.R Hosseinzadeh; M Moayyed; S Maghfouri; S Alipour; B Hajalilou
Abstract
The study area is located in Arasbaran Metallogenic Zone. The rocks of the Baloojeh region includes of Oligo-Miocene quartz-diorite porphyry, gabbro-diorite, quartz-monzonite and granodiorite. The quartz diorite is the main host rock of porphyry type Cu-Mo mineralization in the Baloojeh deposit, but ...
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The study area is located in Arasbaran Metallogenic Zone. The rocks of the Baloojeh region includes of Oligo-Miocene quartz-diorite porphyry, gabbro-diorite, quartz-monzonite and granodiorite. The quartz diorite is the main host rock of porphyry type Cu-Mo mineralization in the Baloojeh deposit, but also in the other intrusive porphyries, copper mineralization can be seen. Much of the mineralization in the Baloojeh deposit is dispersive and vein- veinlet type. Based on the structure, mineralogy and texture, the Baloojeh vein- veinlets can be divided into four different groups. These veins - veinlets contains sulfide (pyrite, molybdenite, chalcopyrite, boehrnite, galena, and sphalerite), hydroxide and oxide (magnetite, hematite and goethite) and carbonate (malachite and azurite) minerals. Similar to other Cu- Mo porphyry deposits, the Baloojeh deposit contains of potassic, phyllic, argillic and propylitic alterations. The parent magma of intrusives has calk-alkaline to shoshonitic character that implaced in a post-collisional magmatic arc. The fluid inclusion study has been done on the different groups of veinlets. These studies suggest high temperature (221- 381 C°) and high salinity (5- 45 % NaCl) hydrothermal fluid and the occurrence of boiling phenomena in the ore- forming hydrothermal fluids of the Bloojeh deposit.
M.A Rajabzadeh; S Esmaeili
Abstract
The Jian copper deposit is hosted by the Permo-Triassic SurianVolcano-Sedimentary Complex on the eastern edge of the Sanandaj-SirjanMetamorphic Zone at a distance of 195 Km NE of Shiraz, southwestern Iran. The complex consists mainly of metabasalt, chlorite-quartz schist, chlorite-muscovite schist, ...
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The Jian copper deposit is hosted by the Permo-Triassic SurianVolcano-Sedimentary Complex on the eastern edge of the Sanandaj-SirjanMetamorphic Zone at a distance of 195 Km NE of Shiraz, southwestern Iran. The complex consists mainly of metabasalt, chlorite-quartz schist, chlorite-muscovite schist, mica schist and graphite schist. Pyrite is the most important sulfide and chalcopyrite is the major Cu-bearing mineral occurred as massive ores in lens to nearly tabular shapes and also as disseminations in veins and veinlets hosted by chlorite-quartz schist. On the basis of geochemical data the mobile elements (Na, k, Ba, Sr) and rare earth elements (REE) show an intense influence of mineralizing fluid on the host rocks. Co/Ni=8.02, Y/Ho (29.09-32.5) and Se/S*106
M Ehteshami-Moinabadi; A Yassaghi
Abstract
The assessment of deformation condition of the Mosha Fault during Middle-Late Miocene carried out using microstructure and thermometry of fluid inclusions within calcite veins in the fault zone. Based on intra-crystalline deformation of quartz grains, calcite twin, and thermometry of primary fluid inclusions ...
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The assessment of deformation condition of the Mosha Fault during Middle-Late Miocene carried out using microstructure and thermometry of fluid inclusions within calcite veins in the fault zone. Based on intra-crystalline deformation of quartz grains, calcite twin, and thermometry of primary fluid inclusions in the calcite veins inside the Mosha fault zone, the maximum estimated deformation temperature of the Mosha fault is 350o c during Tertiary. Calculated pressure of the fault zone using fluid inclusion data is an underestimation of real pressure because the calcite veins formed in the last stages of deformation. Considering the tectonic setting of South Central Alborz and assuming a geothermal gradient ranging between 25-35oc/Km for the region from Eocene to the late Miocene, the maximum temperature of 350o c represents the depth between 10 to 14 Km in adiabatic condition. This depth range means a fault zone pressure between 2.5 to 4 kbar for the Mosha Fault zone during Tertiary, which is in correlation to recent seismic data that confirmed maximum fault activity in the depth between 10 to 15 Km.
T Nabaei; A Khakzad; M Hoseini; S.R Mehrnia
Abstract
The study area is a portion of Urmia-Bazman Magmatic Belt in the Central Iran Structural Zone that located in the south of Boein-Zahra city (Qazvin province). In this area, volcanic and pyroclastic rocks incised by a plutonic body and around and within this pluton, a large extensive alteration occurred. ...
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The study area is a portion of Urmia-Bazman Magmatic Belt in the Central Iran Structural Zone that located in the south of Boein-Zahra city (Qazvin province). In this area, volcanic and pyroclastic rocks incised by a plutonic body and around and within this pluton, a large extensive alteration occurred. In this study, Landsat 7 data (ETM+) employed and general alteration trend in the area was mapped by conventional methods of Color Composite (RGB), Band Rationing and specially Principal Components Analysis (PCA). All of the three methods are found to be effective for obtaining generalized information about the alteration of the image area. Principal Components Analysis (PCA) and especially Selective Principal Components Analysis (Crosta technique) found to be the best effective method in delineating the borders of clay and iron oxide altered areas. In the high altered wall rocks, mineralogical analysis results (XRD method) indicated two forms of vertical and horizontal zoning. In this case, in vertical zoning in order from down to up, advanced argillic, alunitic and silicified zones and in horizontal zoning from fault surface toward wallrocks, advanced argillic and propylitic zones were distinguished. The mineralogical composition of zones and form of zoning indicates that this type of alteration is "acid sulfate". The study of fluid inclusion of quartz crystals in silicic veins, indicated that liquid and vapor phases (LV) are present and study of them resulted in calculation of salinity percentages between 16.8 to 19.2 (NaCl wt%) and homogenization temperatures between 204oC to 280oC.
B Mehrabi; M Ghasemi Siani; E Tale Fazel
Abstract
The Torud-Chah Shirin volcanic-intrusive arc, in the south of Kavir-e-Chah Jam depression (SW of Damghan), hosted many Pb, Zn, Cu, Ag and Au occurrences and deposits. Cheshmeh Hafez (Pb-Zn±Cu±Ag±Au) and Challu (Cu-Au±Ag) polymetallic vein-type ore deposits are the major one ...
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The Torud-Chah Shirin volcanic-intrusive arc, in the south of Kavir-e-Chah Jam depression (SW of Damghan), hosted many Pb, Zn, Cu, Ag and Au occurrences and deposits. Cheshmeh Hafez (Pb-Zn±Cu±Ag±Au) and Challu (Cu-Au±Ag) polymetallic vein-type ore deposits are the major one located in the central part. The Tertiary calc-alkaline volcanism and related mineralization occurred along the main Anjillo fault in the north and the Torud fault in the south with NW-SE trend. The exposed rocks in the Torud-Chah Shirin consist of volcaniclastic sequence composed of siltstone, thin bedded sandstone, lapilli tuff and volcano breccias and mostly andesitic and andesitic-basalt flows. Main host rocks at Cheshmeh Hafez are andesite and andesitic-basalt, while in Challu are trachy-andesite and basaltic trachyandesite, hosted polymetal hydrothermal mineralization in the area. Mineralization in the Cheshmeh Hafez occurred in three main stage includes stage 1) vein and disseminated pyrite and chalcopyrite hosted in quartz with homogenization temperature of 188 to 238°C and salinity of 6 to 14 wt.% NaCl equiv, stage 2) main sulfide mineralization with vein, disseminated and brecciate texture hosted in quartz with homogenization temperature of 243 to 276°C and salinity of 11 to 18 wt.% NaCl equiv and stage 3) replacement mineralization and vein-type (quartz and barren calcite) with homogenization temperature of 148 to 185°C and salinity of 4 to 11 wt.% NaCl equiv. Mineralization in the Challu district with low expanse and simple mineralogy occurred at two stage composed of stage 1) vein and veinlet pre-mineralization stage includes specularite, magnetite, chalcopyrite and pyrite (I) hosted in quartz with homogenization temperature of 332 to 356°C and salinity of 7 to 11 wt.% NaCl equiv and stage 2) brecciate and stock-work post-mineralization stage includes pyrite (II), bornite, tetrahedrite, vein-type calcite and chlorite with homogenization temperature of 290 to 322°C and salinity of 3 to 7 wt.% NaCl equiv. According to the recent studies, it can be inferred that with distance increasing from Challu district to Chesmeh Hafez mining area, homogenization temperatures (Th), salinity and depth of mineralization decreases gradually and mineralization at Challu and Cheshmeh Hafez districts have characteristics of an individual mineralization system that caused by mixing of hydrothermal fluid with meteoric water.
E. Haghighi; S. Alirezaei; E. Ashrafpour
Abstract
The Cheshmeh Hafez deposit in Torud-Chahshirin Range, north-central Iran, consists of a polymetal vein mineralization in Cenozoic volcanic host rocks of dominantly basaltic andesite and dacite compositions. The main ore vein, 1800 m long and <1 – 5 m wide, occurs discontinuously in a north-south ...
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The Cheshmeh Hafez deposit in Torud-Chahshirin Range, north-central Iran, consists of a polymetal vein mineralization in Cenozoic volcanic host rocks of dominantly basaltic andesite and dacite compositions. The main ore vein, 1800 m long and <1 – 5 m wide, occurs discontinuously in a north-south direction, and includes chalcedony, fine- to coarse-grained quartz, and jasperoid, associated with galena and subordinate chalcopyrite, sphalerite, bornite, pyrite, tetrahedrite, specular hematite and siderite. Crustiform bands, consisting of grey chalcedony, jasperoid, milky quartz, and various ore minerals are common, and breccias and comb textures are locally developed, in the vein. Supergene processes led to the replacement of galena by cerussite, and of hypogene copper minerals (chalcopyrite and bornite) by covellite and malachite. The main ore vein is accompanied by several smaller quartz and calcite veins in NE-SW and E-W directions, respectively, where the calcite veins are barren. Alteration related to mineralization is restricted to thin halos bordering the vein, and consists of quartz, chlorite, calcite, kaolinite and sericite (illite). Fluid inclusions in quartz associated with ore minerals are studied. Most inclusions are two-phase, liquid-rich, at room temperatures; few are vapor-dominant, and few consist solely of liquid. Primary fluid inclusions display low to moderate homogenization temperatures (135-285) and salinities (1-13 wt% NaCl equivalents). The δ34S values for the ore fluids in equilibrium with the sulfide minerals fall in the range -1.6 to +4.1‰ and suggest a magmatic source for sulfur. The ore and gangue mineralogy, and the alteration assemblages, suggest that the ore fluids were reduced and near-neutral in nature. This, combined with the metal contents, Ag/Au ratio between 16 to 25, iron- poor sphalerite, the crustiform and colloform textures, and the Th and salinity values, imply that mineralization at Cheshmeh Hafez is of epithermal, intermediate- sulfidation, character. The alteration assemblage at Cheshmeh Hafez is indicative of a sub-type of intermediate- sulfidation epithermal deposits with a tendency towards low-sulfidation type
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.
E. Ashrafpour; S. Alirezaei; K.M. Ansdell
Abstract
Arghash gold district is located in the eastern Sabzevar zone. The basement of this zone consists of Precambrian metamorphosed rocks and Paleozoic-Mesozoic epicontinental sediments. The basement is covered by Upper Cretaceous ophiolitic mélange and Tertiary magmatic and sedimentary rocks. Arghash ...
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Arghash gold district is located in the eastern Sabzevar zone. The basement of this zone consists of Precambrian metamorphosed rocks and Paleozoic-Mesozoic epicontinental sediments. The basement is covered by Upper Cretaceous ophiolitic mélange and Tertiary magmatic and sedimentary rocks. Arghash district includes five gold-bearing vein systems, Au-I–Au-V, and one Sb vein, occurring in Tertiary intermediate to silicic volcanic rocks, tuffs, granite, and diorite. Intensive alteration, dominated by clay minerals, is confined to 1 to 5 m from the veins. The intensive argillic alteration is bordered by irregular zones of moderate to weak argillic and propylitic alterations.
Mineralization is mostly confined to veins. Pyrite is the main sulfide mineral and includes four generations: 1) disseminated euhedral to anhedral, fine- to coarse-grained pyrite (Py-I), locally associated with minor chalcopyrite, marcasite, tetrahedrite-tennantite, and arsenopyrite; native gold grains occur in quartz associated with the pyrite; 2) framboidal pyrite (Py-II) which contains up to 960 ppm Au; 3) arsenian pyrite overgrowths (Py-III) which contain up to 1980 ppm Au; and 4) fracture-filling, anhedral, barren, late stage pyrite (Py-IV). Gold occurs as nanoparticles as well as unstable solid solutions in the framboidal and arsenian pyrite.
Homogenization temperature (Th) and salinity were measured on fluid inclusions in several quartz and calcite samples. Th varies from 186º to 357ºC, and 169º to 313ºC, and salinity from 0.2 to 5.3 and 0.7 to 1.9 wt. percent NaCl equiv. for quartz and calcite, respectively. The low salinity character of the ore forming fluid is consistent with the ore mineralogy and metal contents. The variation in salinity and Th could be explained by a combination of boiling and mixing (dilution) of a hotter and more saline fluid with a cooler and less saline fluid. These processes led to the deposition of gold in the veins. The ore mineralogy, textures, alteration, homogenization temperatures, and salinities, are typical of low-sulfidation epithermal precious metal deposits.
