Economic Geology
Mohammad Ali Rajabzadeh; Mohammad Amini
Abstract
This is the first report on the presence of podiform chromititeLenses associated with the Marivan ophiolite. These ore deposits with granular massive fabric are hosted by dunite and harzburgite occurred in south Marivan city. Chemistry of chromian spinel in the chromite Lenses indicated that Cr# for ...
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This is the first report on the presence of podiform chromititeLenses associated with the Marivan ophiolite. These ore deposits with granular massive fabric are hosted by dunite and harzburgite occurred in south Marivan city. Chemistry of chromian spinel in the chromite Lenses indicated that Cr# for two ore occurrences is high (0.85) with very low TiO2, but for the other ore occurrence is lower (0.67) with higher TiO2 (0.05). The finding shows that the chromite ore Lenses and consequently their host ophiolite were developed in two different geotectonical settings. Geochemical data indicated that some of the studied ore deposits occurred during the opening of oceanic crust in a Mid Oceanic Ridge setting from a tholeiitic magma while the others were fractionated form a boninitic melt in a Supra Subduction Zone. Formation of these ore Lenses and the host rocks occurred in response to the very fast divergence and then convergence of Neo-Tethys oceanic crust. A wide range of gabbros including coarse-grained gabbro, melagabbro and microgabbro host ilmenite, magnetite and titanite in three regions at the northwest of Kamyaran (Yakhtekhan village), the east of Sarvabad (Mianeh village) and the south of Marivan (Dragashikhan-Vyseh villages). Ilmenite is found in all the three regions, but magnetite and titanite are only found in the east of Sarvabad. Plagioclase (andesine-labradorite) and diopside, the main rock-forming minerals with minor augite, olivine and amphibole are the minerals of the host rocks. The chemical composition of the ilmenites showed that the average concentration of TiO2 increases from Kamyaran (43.19 wt.%) to Sarvabad (46.09 wt.%) and then to Marivan (47.42 wt.%). These minerals occur as interstitial fine to medium grains (up to 1.5 mm) and often in the amoeboid, anhedral and to a lesser extent as subhedral forms. Based on textural and mineral chemistry evidence, mineralization of titanium occurred as the result of magma oxidation. The oxidation of magma resulted in the formation of iron-titanium immiscible liquid droplets, following the plagioclase crystallization.
Economic Geology
Seyed Mehran Heidari; Sara Safavy; Afshin Akbarpour; Azra Hassanlou; Bahram Mohaghegh
Abstract
Saveh-Razan copper (± gold) area, with WNW direction in the northwest of Urmia-Dokhtar magmatic belt, with the highest reaction to right-sided shear zones and structural trend change during the Oligomyocene, leads to the placement of semi-deep Oligomyocene diorite massifs in shallow rock depths. ...
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Saveh-Razan copper (± gold) area, with WNW direction in the northwest of Urmia-Dokhtar magmatic belt, with the highest reaction to right-sided shear zones and structural trend change during the Oligomyocene, leads to the placement of semi-deep Oligomyocene diorite massifs in shallow rock depths. It is an Eocene volcano. By creating different types of mass-related hydrothermal alteration (propylitic, intermediate-advanced argillaceous, and phyllite) along the fractures, the system concentrates the mineralizations in quartz-sulfide veins, hydrothermal incisions, and concentrated sulfide-bearing filaments. Common features of metallurgy in this area are fluid homogenization temperature between 250 to 350 ° C and salinity range of 6-28% by weight of salt, containing CO2 gas and liquid phase of liquid and the presence of sulfides such as pyrite, chalcopyrite, burnite, chalcocite and sulfosalts in related reserves. There is also more gold than silver. Therefore, these features are most similar to the mass-related intermediate-type epitermal deposits that form in calcoalkalkene magmatic arcs.
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
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.
J. Rasouli; M. Gorbani
Abstract
Delfard area is located in the northwestern of Jiroft, formed the northwestern part of the Jabālbārez granitoid complex, in Uromiyeh- Dokhtar magmatic belt. The Jabālbārez granitoid complex has a wide range of rocks inclusive from diorite to alkali granite, which were formed by magmatic differentiation ...
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Delfard area is located in the northwestern of Jiroft, formed the northwestern part of the Jabālbārez granitoid complex, in Uromiyeh- Dokhtar magmatic belt. The Jabālbārez granitoid complex has a wide range of rocks inclusive from diorite to alkali granite, which were formed by magmatic differentiation process over the several course of consecutive pulses. Last pulses are masses of porphyry that showed evidence of copper mineralization. One of these intrusive bodies is Delfard. Copper mineralization in Delfard area is more important than other parts of Jabālbārez. Consequently, in the area, three porphyry masses showing the evidence of porphyry copper mineralization. Chalcopyrite, Pyrite, Malachite, Azurite and Magnetite are indicative minerals. Alteration zones in Delfard area are silicic, potassic, arjelic, phyllic, and propylitic that can be correlated with Lovell and Gilbert model. According to studies, Delfard has high potential for exploration and drilling. The average copper content in the ore is about 1800 ppm. Petrogenesis review of the mafic rocks in Delfard area shows that these rocks originated from a richer source than NMORB. In addition, the rocks of Delfard area are Flux melting pointer that happened in the subduction of oceanic crust under the adjacent crust. In other words, the sequence of calc-alkaline rocks of Delfard area attributed to compressional tectonic regime that intrusived and erupted along the Uromiyeh- Dokhtar zone with development and high volume in the form of magmatic horizons. Finally, petrogenesis of studied granite series is similar to the calc-alkaline granitoids, which was originated from basaltic magma mantle metasomatised by fluids from the subducted slab. Based on zircon U-Pb geochronology,the age of Delfard granitoid is 15/83±1/3 Ma. One can imagine that, magmatic differentiation process was completed in a short time and intrusive body was sequentially penetrated and placed in the earth's crust in a short time.
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.
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.
R Ferdowsi; A.A Calagari; M.R Hosseinzadeh; K Siahcheshm
Abstract
Astarghan area is located in ~ 50 km of north of Tabriz, southeast of Kharvana, East-Azarbaidjn. The area is a part of Gharadagh- Arasbaran metallogenic belt. The most important units in the area is a hypabyssal prophyritic to granular granodioritic intrusive body of Oligo-Miocene and flysch- type sedimentry ...
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Astarghan area is located in ~ 50 km of north of Tabriz, southeast of Kharvana, East-Azarbaidjn. The area is a part of Gharadagh- Arasbaran metallogenic belt. The most important units in the area is a hypabyssal prophyritic to granular granodioritic intrusive body of Oligo-Miocene and flysch- type sedimentry sequence of limestone, limy sandstone and marl (Paleocene-Eocene). Intrusion of the stock into the sedimentary rocks caused them to convert into a series of metasomatites and contact metamorphic rocks. Geostatistic studies on stream sediments and heavy mineral were done and include data processing, (i.e. normalization, univariate and multivariate analysis), and ultimately preparation of anomaly maps. The correlation coefficients among elements were determined. Elements that show positive correlations with gold are Cu, Hg, Pb, As, Sb, Ag, Bi and Mo. The results of preliminary regional geochemical explorations have led to discovery of two anomalous zones for gold; grade 1 and grade 2. The anomalies were verified by studies on heavy minerals in stream sediments and mineralized and altered samples taken from gold anomalous zones. The most important indentified heavy minerals include magnetite, malachite, gold, micaseous hematite, pyrite, galena, cerussite, pyrite- limonite, goethite, limonite, barite, hematite, pyrite- oxide which are affiliated with alteration and mineralzation zones. The major alterations in the area are argillic, sericitic and propylitic developed along the vein’s walls. Field and analytic studies done on samples taken from the gold anomalous zones led to identification of epithermal gold veins having over 4.5 ppm gold grade. The concordance of anomaly map with tectonic map and altered zones indicate that the faulted and fractured zones have played a crucial role in creation of gold anomalous zones. The incorporation of these data in the area led to introduction of several anomalous zones belonging to Au, Ag, Cu, As and Pb that can be used as passfinders for epithermal gold.
Gh Sohrabi; M.R Hosseinzadeh; A.A Calagari; B Hadjalilu
Abstract
The study area is located in north of East-Azarabaidjan (northwest of Iran). The most important intrusive bodies in the area include the Gharehdagh and Shivardagh batholiths and porphyry stocks of Sungun and Haftcheshmeh. The petrological and petrographical studies show that the composition of intrusives ...
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The study area is located in north of East-Azarabaidjan (northwest of Iran). The most important intrusive bodies in the area include the Gharehdagh and Shivardagh batholiths and porphyry stocks of Sungun and Haftcheshmeh. The petrological and petrographical studies show that the composition of intrusives varies from gabbro through diorite, monzonite, and granodiorite to granite. All bodies are I-type and mostly metaluminous and calc-alkaline with medium to high potassium belonging to volcanic arcs. The most important alterations in ore-bearing areas include silicic, potassic, propylitic, phyllic, and argillic. Mo mineralization occurred mostly in quartz veins and veinlets within the potassic zone in porphyry systems and veins and also in endoskarn associated with garnet skarns. The amount of Mo increases in differentiated and biotite-bearing acidic bodies that have high values of Si, K, Rb, and REEs. The intrusive bodies enriched with K, Rb, and Ba and depleted in Zr, Ta, Y, Yb, and Nb elements indicate metasomatism of the upper mantle by subducting oceanic crust and subsequent generation of magma and its passes through relatively thick crust. The bodies bearing Mo mineralization are located mainly in the center of batholiths and have quartz monzonitic and granodioritic compositions.
S Afzali; N Nezafati; M Ghaderi; J Ghalamghash; M.R Ghassemi; A Karimi Bavandpur
Abstract
The Gazestan magnetite–apatite deposit is situated 78 km east of Bafq. The Gazestan deposit is located in Bafq-Poshtebadam subzone of Central Iran structural zone. The rock units in the area belong to the Rizu series and consist of carbonate rocks, shale, tuff, sandstone and volcanics. In addition ...
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The Gazestan magnetite–apatite deposit is situated 78 km east of Bafq. The Gazestan deposit is located in Bafq-Poshtebadam subzone of Central Iran structural zone. The rock units in the area belong to the Rizu series and consist of carbonate rocks, shale, tuff, sandstone and volcanics. In addition to sedimentary and volcanic rocks, intrusive rocks in the form of stock and dyke outcrop as diorite gabbro, gabbro, diabase, quartz-monzonite and granite in various places. The green rocks with acidic to intermediate composition (trachyte and dacite demonstrate green color due to alteration) host iron and phosphate mineralization which in some localities, show subvolcanic facies. The alteration is more obvious in the volcanic rocks and includes chloritization, argillic, silicification, and also formation of mafic minerals such as epidote, tremolite and actinolite. The host rocks are strongly altered. Mineralization at the Gazestan deposit comprises a combination of iron oxides and apatite with various ratios accompanied by quartz and calcite, observed in different forms mainly within the trachytic-dacitic rocks and a small proportion in the rhyolites. Five forms of mineralization are distinguished in the area including massive iron ore with minor apatite, apatite-magnetite ore, irregular vein-veinlets (stockwork) in the brecciated green rocks, disseminated, and pure massive apatite veins. The host rocks in the Gazestan area plot on calc-alkaline field. Comparison of the most important characteristics of the Gazestan deposit (including tectonic setting, host rock, mineralogy, alteration, structure and texture) with those of various types of mineralization in the world suggest that the deposit is quite similar to the iron oxide - apatite deposits.
M Abdi; M.H Karimpour; M.H Zarinkoob
Abstract
The main purpose of this study is processing of raw data by factor analysis method and having interpretation and integration them by geological, alteration and mineralization data. The distinctiveness of third factor of factor analysis for Au, Mo and W and the coincidence of third factor anomalies by ...
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The main purpose of this study is processing of raw data by factor analysis method and having interpretation and integration them by geological, alteration and mineralization data. The distinctiveness of third factor of factor analysis for Au, Mo and W and the coincidence of third factor anomalies by gold, high primary sulfide bearing area, secondary iron oxide and sericitic and silicic alterationrevealed that the third factor of factor analysis is the agent of mineralization in the study area. The suitable tectonic setting, shallow depth intrusiveswithintermediate composition, calc-alkalineand oxidant magmatism, anomaly of gold and disseminated mineralization in thehost rock and sulfide veinlet accompanied byabundant secondary iron oxide providedproperconditions for porphyry and epithermal type gold mineralization in the study area.
S Soltaninejad; B Shafiei
Abstract
The Now-Chun deposit, in the Kerman porphyry copper belt, with proved reserve of 268 Mt ore grading 0.034% Mo (100 ppm cut off) and 62 Mt ore grading 0.43% Cu (0.25 cut off), is the first known occurrence of Mo-rich,relatively Cu-poor porphyry mineralization in Iran which is studied from the mineralogical, ...
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The Now-Chun deposit, in the Kerman porphyry copper belt, with proved reserve of 268 Mt ore grading 0.034% Mo (100 ppm cut off) and 62 Mt ore grading 0.43% Cu (0.25 cut off), is the first known occurrence of Mo-rich,relatively Cu-poor porphyry mineralization in Iran which is studied from the mineralogical, l, and genetic point of view. The alteration and mineralization of the Now-Chun deposit is related to the highly differentiated porphyritic stock (rhyodacite) belonging to the Oligo-Miocene Mamzar batholith. Based on the present study, the main part of Mo and Cu mineralization in the Now-Chun deposit occurred more in the form of cross-cutting veinlets (stockwork) and less as dissemination type. The presence of molybdenite with/without chalcopyrite association in quartz-anhydrite-orthoclase-biotite potassic veinlets and chalcopyrite occurrence in primary quartz-magnetite veinlets is indicative of the priority of part of the Cu mineralization respect to the Mo during the primary stage of mineralization. The initial mineralization of Mo in the form of molybdenite occurred in quartz-anhydrite-orthoclase-biotite-pyrite-chalcopyrite. The weak correlation between Mo and Cu in the potassic alteration zone (r= -0.2) especially in the high grade ores indicates the difference between the enrichment conditions of both elements in responsible hydrothermal fluids for this alteration and mineralization zone. The presence of thick quartz-pyrite-chalcopyrite veinlets with sericitic halo and quartz-molybdenite without alteration halo either as independent or as intruded within early veinlets (quartz-molybdenite-anhydrite-orthoclase-biotite) have been associated with increasing of Mo and Cu grades in moderately phyllic alteration zone (sericitic and silicified rocks). The positive correlation between Mo and Cu in moderate phyllic zone (r≥ 0.0 to +0.5) which affected potassic ores indicates the similar behavior of both Mo and Cu during formation and evolution of the hydrothermal solution, which is responsible for the alteration and mineralization in the phyllic zone. This study revealed that the main concentration of Mo occurred in deep parts (potassic zone) of the deposit; whereas, Cu is associated with the shallow parts, especially with moderate phyllic zone which affected the potassic zone. As a result, the high grade Mo ores are not Cu-rich and vice versa. The present study indicated that the Now-Chun deposit in comparison with the Sar Cheshmeh deposit (Cu-Mo porphyry) is categorized within the Mo-Cu porphyry deposits. This sub-group of porphyry Cu and Mo deposit is attributed to the function of the Mo-rich and relatively Cu-poor hydrothermal fluids. The more differentiated composition of the ore-hosting porphyry in the Now-Chun deposit (rhyodacite) in comparison with the Sar Cheshmeh porphyry stock (granodiorite-quartzmonzonite), which indicates the late water saturation in its parent magma, was probably the factor of generating such fluids that could segregate the significant proportion of Mo in respect to Cu from the residual melts into H2O, alkalies and silica-enriched fluid phase which ultimately resulted in forming the Mo-Cu porphyry deposit.
S Alipour; A Abedini; Sh Abdali
Abstract
The Heydar-Abad laterite horizon is located at 65 km south of Urmia, West Azarbaidjan province. This horizon was developed as stratiform bed within the carbonate rocks of the late Permian Ruteh Formation. Based on the petrographical and mineralographical studies,the ores of this horizon contain micro-granular, ...
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The Heydar-Abad laterite horizon is located at 65 km south of Urmia, West Azarbaidjan province. This horizon was developed as stratiform bed within the carbonate rocks of the late Permian Ruteh Formation. Based on the petrographical and mineralographical studies,the ores of this horizon contain micro-granular, fluidal-collomorphic, panidiomorphic-granular, spastoidic, pelitomorphic, nodular, and ooidic textures and have an authigenic origin. According to the mineralogical investigations, the ores of this horizon include minerals such as diaspore, corundum, hematite, magnetite, goethite, rutile, paragonite, margarite, amesite, berthierine, montmorillonite, chlorite, chloritoid, muscovite-illite, quartz, pyrite, anhydrite, calcite, and dolomite. The presence of high quantities of silicate minerals indicates immaturity and poor draining system during the development of this residual horizon. The results of chemical analyses show that Eu and Ce anomalies in the ores are within the ranges of 0.67 to 2.74 and 0.86 to 2.16, respectively. The calculations of values of enrichment factor of elements in two selected profiles reveal that two processes of leaching and fixation are major regulators of concentrations of REEs in ores of this horizon. The results obtained from the mineralogical and geochemical studies show that changes of pH of weathering solution, fluctuations of level of ground-waters, alteration intensity, and function of carbonate bedrocks as a geochemical barrier, adsorption, and scavenging have played an important role in distribution of the rare earth elements (REEs) in this deposit. The correlation coefficients show that the secondary phosphates, rutile and muscovite-illite are potential hosts for REEs in the ore.
M Roohafza; S Alipour; A Abedini
Abstract
Ghareh-bolagh area is located in 20 Km of east of Mahabad, south of West-Azarbaidjan province. Carbonate rocks of Bayandour formation and dolomites of Soltanieh formation in this area are the host of mineralizations from Barium, iron and manganese. Based upon mineralogical investigations, barite, magnetite, ...
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Ghareh-bolagh area is located in 20 Km of east of Mahabad, south of West-Azarbaidjan province. Carbonate rocks of Bayandour formation and dolomites of Soltanieh formation in this area are the host of mineralizations from Barium, iron and manganese. Based upon mineralogical investigations, barite, magnetite, hematite, goethite, limonite, pyrolusite were major mineral assemblages of these mineralizations which that is accompanied by chalcopyrite, malachite, azurite, and calcite in low amounts. The most important geochemical characteristic these mineralizations are relative weak differentiation of LREE from HREE in barite and iron-manganese ores, Eu negative anomalies in iron-manganese ores (0.26-0.76) and Eu positive anomalies in barite (7.7-10.51). Incorporation of the obtained results from investigations of field, petrographic and geochemical (analytic data and correlation coefficients between elements) indicate that factors such as changes in physicochemical conditions of environment (pH, Eh, temperature), activity of complexing ligands, and presence of minor mineral phases (clay minerals, zircon, zenotime, and monazite) played important role in distribution of rare earth elements during mineralization and development of these ores.
M. Sakhdari; M. Yazdi; M. Behzadi
Abstract
The Shanegh area is located in central part of Sanandag-Sirjan zone, 28km southeast of Delijan. Rock units exposing in the area consists of sedimentary (carbonate, sandstone, siltstone) volcano- sedimentary (andesite to andesitic tuff, tuff) and intrusive host rocks. The volcano- sedimentary units thought ...
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The Shanegh area is located in central part of Sanandag-Sirjan zone, 28km southeast of Delijan. Rock units exposing in the area consists of sedimentary (carbonate, sandstone, siltstone) volcano- sedimentary (andesite to andesitic tuff, tuff) and intrusive host rocks. The volcano- sedimentary units thought to be of Eocene to Quaternary ages which have been intruded by plutonic units. The main host rocks are monzonite, quartz monzonite, andesite and diorite. The host rocks have been altered by pervasive hydrothermal fluids. The alterations are sericitization, kaolinitization, carbonatization and silicification. The host rocks are characterized by fault or shear zones, vein systems, stockwork and dyke mineralization. Ore mineral assemblages are pyrite, chalcopyrite, Fe-oxide and Fe-hydroxides. We did not find gold minerals in our microscopic studies but the gold has been found in the lithogeochemical exploration. The results show that maximum grade of gold in some veins is about 2760 ppb and the mean grade of gold about 80 ppb. Comparing shanegh area main characteristics with epithermal gold deposits, shanegh area has the most similarities with epithermal gold mineralization; therefore, it is considered to be of this type.
L. Ebadi; S.A. Alavi; Sh. Shafiei
Abstract
Hydrothermal vein and porphyry copper deposits are notable within Eocene volcanic rocks of Shahr-e-Babak area. In this paper, the structural patterns within Shahr-e-Babak area as well as the relationship between structural elements and the emplacement of dikes and hydrothermal vein and porphyry copper ...
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Hydrothermal vein and porphyry copper deposits are notable within Eocene volcanic rocks of Shahr-e-Babak area. In this paper, the structural patterns within Shahr-e-Babak area as well as the relationship between structural elements and the emplacement of dikes and hydrothermal vein and porphyry copper deposits have been discussed. Three fault trends of WNW-ESE and N-S are recognized in northeastern Shahr-e-Babak according to satellite images and field observations. The WNW-ESE and N-S trending faults are normal faults, while the NE-SW trending faults are sinistral faults with normal component. Two trends are recognized for the dikes in Shahr-e-Babak area namely, WNW-ESE(T2) and N-S (T1) following the trends of preexisting fractures in the area. The existence of an extensional system is recognized by the pattern of tension gashes and Pennant and the presence of extensional joints in the area. The shift in s1 direction from NE-SW to N-S, confirm the presence of some rotation in the area. The rotation in a transpressional regime caused the development of extensional structures in the Shahr-e-Babak area; the extensional structures provided the space for the passage of ore fluids and the emplacement of polymetallic vein and porphyry copper deposits in northeastern Shahr-e-Babak
N. Taghipour; A. Aftabi; M.R. Ramezani
Abstract
The Miduk porphyry copper deposit is located in 85 Km northwest of Sarcheshmeh porphyry copper deposit, Kerman province. The deposit is hosted by Eocene volcanic rocks of andesite-basalt composition. The porphyry-type mineralization is associated with two calc-alkaline intrusive phases (P1 and Miduk ...
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The Miduk porphyry copper deposit is located in 85 Km northwest of Sarcheshmeh porphyry copper deposit, Kerman province. The deposit is hosted by Eocene volcanic rocks of andesite-basalt composition. The porphyry-type mineralization is associated with two calc-alkaline intrusive phases (P1 and Miduk porphyry) of Miocene age. Five hypogene alteration zones are distinguished in the Miduk deposit, magnetite-rich potassic, potassic, potassic-phyllic, phyllic and propylitic. The main stage of mineralization consists of chalcopyrite, magnetite and anhydrite in potassic alteration zone. The mineralization is mostly associated with Miduk porphyry intrusive phase. Three different types of biotite including magmatic, magmatic affected by hydrothermal fluids and secondary are distinguished at the Miduk deposit. Magmatic type biotites affected by hydrothermal fluids and secondary biotites contain higher XMg values than the magmatic biotites. The XMg are positively correlated with Si, Al, Mg, K, Mg/Ti, but negatively correlated with Al×Ti, Fe, Na, Fe/Ti contents. The variations of Cu, Mo, Au and Ag are controlled by vein - type alteration and mineralization zones. The tonnage of deposit is about 170 Mt with average grade of 0.82 % Cu, 0.007% Mo, 82 ppb Au and 1.8 ppm Ag, respectively. Highest values of Mo and Au occur in leached and oxide, supergene sulfide mineralization, phyllic and potassic-phyllic alteration zones, respectively. Gold displays positive correlation with Cu in magnetite-rich potassic and potassic alteration zones. Based on petrography, mineralogy, alteration halos and patterns of Cu, Au, Ag and Mo, the Miduk porphyry copper deposit is similar to those of continental arc setting porphyry copper deposits.
A. Akbarpour; A. Rasa; M. Mehrpartou
Abstract
The Masjeddaghi area is a part of Alborz-Azarbaijan Zone and located in the Jolfa 1:100000 geological map sheet. The oldest rock units cropped out widely in the south and northeast of the area belong to the Eocene flysch-type sediments. The other outcrops consist mainly of volcanic rock complex of andesites ...
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The Masjeddaghi area is a part of Alborz-Azarbaijan Zone and located in the Jolfa 1:100000 geological map sheet. The oldest rock units cropped out widely in the south and northeast of the area belong to the Eocene flysch-type sediments. The other outcrops consist mainly of volcanic rock complex of andesites and trachyandesites affected by quartz monzonite intrusion and caused alteration of phyllic and carbonate phyllic type. The mineralization in volcanic complex is also accompanied by quartz and barite veins. The study of alterated zone around veins shows sericite, silicified, prophillitic, chloritic and alunite (jarosite) alterations. Investigation of alteration zones around mineralized veins shows epithermal gold ore in which alunitic alteration (jarocite) is the most important characteristics. The result of the study on alteration and extension of altered zones in the whole study area give rise to the probability of porphyry type copper deposit (potassic, phyllic, argillic and prophylitic alteration zone).