Remote Sensing
Mahya Nazarian; Mohammad Lotfi; Arash Gourabjeripour; Majid Ghasemi Siani
Abstract
The Chomalu Polymetallic deposit is located in western part of Alborz magmatic belt (Alborz-Azarbaijan) and central part of Tarom-Hashtjin metallogenic province. Eocene volcanic settings in the Chomalu deposit consist of basic rocks (olivinebasalt), intermediate (andesite basalt, andesite to trachyandesite) ...
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The Chomalu Polymetallic deposit is located in western part of Alborz magmatic belt (Alborz-Azarbaijan) and central part of Tarom-Hashtjin metallogenic province. Eocene volcanic settings in the Chomalu deposit consist of basic rocks (olivinebasalt), intermediate (andesite basalt, andesite to trachyandesite) and acidic rocks (dacite to rhyolite) which is intruded by quartz monzodiorite, monzosyenite and quartz monzonite intrusive rocks of Eocene. The main texture of volcanic rocks is more porphyritic. Olivine and plagioclase are the main phenocrysts in the olivinebasalt, andesite rocks compose of plagioclase and clinopyroxene and dacite to rhyolite consist of plagioclase, alkali feldspar and quartz. On the basis of AFM diagram, Chomalu volcanic rocks located in the high- K calc- alkaline to shoshonitic affinities in relation to subduction zone magmatism. Primitive mantle-normalized of volcanic rocks indicate that LILE enrichment and HFSE depletion in consistent with subduction zone magmatism. Chondrite-normalized REE patterns show LREE/HREE enrichment. Geochemical results suggesting primary source magmas source for volcanic rocks were generated by partial melting of the metasomatized lithospheric mantle-wedge in relation to subduction arc and were subsequently affected by both fractional crystallization and crustal contamination during magmatic evolution.
Economic Geology
Fatemeh Sabahi; Mohammad Lotfi; Peyman Afzal; nima nezafati
Abstract
Gardaneshir carbonate-hosted Pb-Zn deposit on the ground of study area located southwest of Ardestan in Isfahan province. Base on lithostratigraphy,the main structure, besides the small outcrops of Jurassic shales, has been made up of carbonate and detrital rock materials depending on Paleozoic,Triassic ...
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Gardaneshir carbonate-hosted Pb-Zn deposit on the ground of study area located southwest of Ardestan in Isfahan province. Base on lithostratigraphy,the main structure, besides the small outcrops of Jurassic shales, has been made up of carbonate and detrital rock materials depending on Paleozoic,Triassic and Cretaceous time stages. Dolomitic carbonate which is attributed to Shotori Formation , played the major role of host rock in ore-mineralization. Ore-mineral description obtained from the mineralized zone and caused the following ore-paragenesis in ascending order.of:pyrite,chalcopyrite,galena,sphalerite,malachite,cerussite,smithsonite,iron oxides and gangues of barite, quartz and calcite. Physico-chemical information of ore-solutions performed by entrapped fluid inclusion studies in gangue minerals. Liquid-rich two phase(L+V) inclusions as predominant types were recognized. These type of inclusions are homogenized into liquid state with a range of TH and related salinities between; TH :78 to 183 and 216 to 283°C, Salinity:3.5 to 9.7 and 10.2 to 25 wt% NaCl eq. The microthermometric data reflect the nature of two population of fluid inclusions originating from different sources. The source materials could have been provided by basinal brines, derived during compaction of sediments in a shallow sea environment and by movement into sediments, the stratabound Pb-Zn deposit are formed. Furthermore, the negative delta value ranges(δ34S) from -0.6 ‰ to -20.4 ‰ that have been extracted by galena can be an evidence of bacterial sulfate reduction in a subsidence sedimentary basin. In conclusion, based on field, mineralogical, fluid inclusion and sulfur isotope evidence, we propose that Gardaneshir Pb-Zn deposit is a stratabound carbonate hosted of Mississipi Valley Type(MVT).
Economic Geology
Z. Zandi; A. R. Jafari rad; A. Gourabjeripour; M. Lotfi
Abstract
The Saheb Fe-Cu skarn deposit is located in the Sanandaj-Sirjan metamorphic belt, SE Saqqez, western Iran and has been formed along the contact between the Oligo-Miocene aged Saheb granitoid and the Permian aged impure calcareous rocks and includes endoskarn and exoskarn. Exoskarn is widely developed ...
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The Saheb Fe-Cu skarn deposit is located in the Sanandaj-Sirjan metamorphic belt, SE Saqqez, western Iran and has been formed along the contact between the Oligo-Miocene aged Saheb granitoid and the Permian aged impure calcareous rocks and includes endoskarn and exoskarn. Exoskarn is widely developed and include garnet and epidote skarn zones. The majority of mineralized zones are concentrated in garnet skarn. The relatively oxidizing mineralogical assemblage of the Saheb skarn includes garnet (andradite-grossular), pyroxene (diopside-hedenbergite), magnetite and hematite. Magnetite is the main and abundant ore mineral throughout the ore deposit. Based on field evidences and microscopic studies of skarn zone samples, two stages of prograde and retrograde alteration are distinguishable. According to the results of sample analysis of Saheb skarn productive intrusive body by XRF and ICP-MS techniques, the combination of this body is chiefly granite to granodiorite-diorite and belong to the I-type granitoids, metaluminous and K-rich calc-alkaline series. The Saheb granitoid is related to the VAG (Volcanic Arc Granite) tectonic setting.
Economic Geology
Mohammad Jabarian; mehrdad karimi; Mohammad Lotfi; kamal noori khankahdani
Abstract
Dehkooye salt dome is located 30 km northeast of Lar in Fars province, Iran. The salt dome occurred in Zagros folded zone where infracambrian thick evaporate strata (Hormoz series) intruded Cenozoic sedimentary rocks. Core of the dome mainly made up of salt and gypsum and overlain by marl, gypsum, limestone, ...
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Dehkooye salt dome is located 30 km northeast of Lar in Fars province, Iran. The salt dome occurred in Zagros folded zone where infracambrian thick evaporate strata (Hormoz series) intruded Cenozoic sedimentary rocks. Core of the dome mainly made up of salt and gypsum and overlain by marl, gypsum, limestone, and dolomitic formations. Besides primary stratiform mineralization, epigenetic iron and copper mineralization occurred mostly within dolomitic lime stone members in the cap rock of the salt dome in Hormoz Formation. Ore mineralogy is simple and includes hematite, minor goethite, and sparse occurrence of magnetite. Chalcopyrite is evident as minor phase. Samples for fluid inclusion studies were collected from sulfide-bearing quartz veins and veinlets. According to homogenization temperature (Th: 172-374 ° C with average 374° C), which in fact represents the boiling point of the irrigation solution, indicate the epithermal to the beginning of hypothermal conditions and the mean of the beginning of the mesothermal. The depth formation of deposit was between 50 to 1500 meters and an average of about 200 meters. The hydrothermal solutions forming the ore deposit, due to their high salinity, have the origin of magmatic brine that have been displaced because of low density and tectonic pressures. This solutions have climbed upwards along faults and fractures and after being mixed with meteoric waters, epigenetic mineralization is created.
R. Pourmasoomi; A. R. Jafari rad; M. Lotfi; P. Afzal
Abstract
The Khankeshi stratabound copper deposit is located in Markazi province, 80 Km SW of Tehran. The area is covered by a sequence of E-W trending lava flows and pyroclastic of Late Eocene age. The volcanic rocks can be classified as trachyandesite and andesite.The rocks contain a ...
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The Khankeshi stratabound copper deposit is located in Markazi province, 80 Km SW of Tehran. The area is covered by a sequence of E-W trending lava flows and pyroclastic of Late Eocene age. The volcanic rocks can be classified as trachyandesite and andesite.The rocks contain a high fraction of potassium calc-alkaline and their geochemical characteristics attribute them to back arc basin and extentional processes. The oldest rocks of the study area are Elta unit , composed of green andesitic tuff located in south eastern of the khankeshi. This part indicates a basin with volcanic activities and exhalites, and green tuff with thin lamination combined with microcrystalline carbonates. On the other hand, presence of carbonate of micrite with framboidal pyrite in this part indicated reducing environment and Exhalites activity by source of sulfur in manto type mineralization in the khankeshi. The host rock is Elt type latite andesite with mega porphyritic texture and involved major ore chalcopyrite, bornite with pyrite and minor chalcocite, covellite, hematite, Goethite and malachite with dolomite and dolosparite veins. Framboidal pyrite is replaced with forms of fine and circle chalcopyrite and bornite in primary micritic background and subhedral crystals into dolosparite veins of crystallized micrititic carbonate micrite in forms of epigenetic that produce the supergene secondary production. This unit with pyroclastics and tuff breccias(Elta unit), indicated volcanic cycle that mineralization of copper, in forms of stratabound, has taken place in it. Local alteration associated with copper mineralization includes weak chloritization, oxidation with local argillic, serecitic and zeolitic. Mineralization is stratabound and copper mineralization occurs as disseminated, vein-veinlet,open space fillings and replacements. Based on fluid inclusion studies on coexisting calcite, Homogenization temperatures are between 129.4 to 227.1(with an average of 175°C).Salinity varies between 1.91 to 13.40(average 12) wt٪ NaCl eq. The depth of fluid inclusion trapping is estimated to be less than 200 meters and ore formation has occurred at pressure values less than 74 bars. Geological, ore mineralogy, ore texture, structures and fluid inclusions characteristics in the khankeshi deposit are similar to those reported from Manto type copper deposits.
M. Jamali; M. R. Ghassemi; M. Lotfi; A. Solgi
Abstract
Kuh-e-Ahan is a high-standing single relief within a rather flat plain, which is located in the north of the Tabas block, near the intersection of the Nayband and Kalmard faults and there are great outcrops of fe-oxide, along with eastern-western faults and fractures in Kooh-e-Ahan area.. ...
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Kuh-e-Ahan is a high-standing single relief within a rather flat plain, which is located in the north of the Tabas block, near the intersection of the Nayband and Kalmard faults and there are great outcrops of fe-oxide, along with eastern-western faults and fractures in Kooh-e-Ahan area.. The present study uses structural and remote sensing methods to discover the mechanism for evolution of the Kuh-e-Ahan, and to understand style of mineralization in the mountain, emphasizing on the role of fractures and major faults. In our remote sensing approach, we used DEM data and Aster satellite images and their filtering in main directions to detect displacements and sudden offsets of lithologic units and changes in drainage patterns. In our field studies, we studied mechanism of the faults, emphasizing on the faults within the Kuh-e-Ahan mining district. The results show N-S faults (Nayband fault trend) and NE-SW faults (Kalmard trend) have a general right-lateral mechanism, and the E-W faults are left-lateral with a reverse component. Structural model developed in this study suggest that strike-slip displacement on conjugate fault provided the space required for ascend and development of hydrothermal mineral deposits within the mine district.
M. Esmaeli; M. Lotfi; N. Nezafati
Abstract
Khalyfehlou Cu deposit (southeast of the Zanjan), is the volcanic-hosted vein-type deposit located in the Tarom metallogenic zon,Western Alborz (northwest of Iran) . Tarom zone consist mainly of volcanic and volcaniclastic rocks of the Karaj Formation (Early to Middle Eocone). Regarding the stratigraphic ...
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Khalyfehlou Cu deposit (southeast of the Zanjan), is the volcanic-hosted vein-type deposit located in the Tarom metallogenic zon,Western Alborz (northwest of Iran) . Tarom zone consist mainly of volcanic and volcaniclastic rocks of the Karaj Formation (Early to Middle Eocone). Regarding the stratigraphic position, the Karaj Formation is divided into two members: Kordkand and Amand. The Kordkand member is overlain by the Amand member .The Amand member is divided into six units, Ea1 through Ea6. The Khalyfehlou Cu deposit is located in Ea5 and Ea6 units of Amand member .The Karaj Formation is interrupted by large and linear intrusions with calc alkaline affinities. Host rocks are green tuffs and, rarely, andesites. The patterns of rare earth elements in the studied samples indicate the negative anomaly of Eu element due to plagioclase subtraction. In all the samples, the enrichment of light rare earth elements (LREE) and large lithophil ion (LILE) elements and the depletion of strong field strength elements (HFSE) are observed. This probably indicates the common origin of these rocks. Main minerals include chalcopyrite, bornite, chalcocite, and covellite and gangue minerals including quartz, sericite, and calcite. In this paper the origin of ore-forming fluids and genesis of Khalyfehlou Cu deposit is studied using sulfur and oxygen isotope data. The sulfur isotope values for the chalcopyrite range from −2.0 to −5.3‰. Negative sulfur isotopes values and the occurrence of framboidal pyrite in the tuffaceous sandstone host rocks suggests a sedimentary origin for the sulfur. The oxygen isotope composition of quartz from the veins ranges from 12.3 to 14.3‰. The δ18Ofluid values calculated from the oxygen isotope data range from 0.6‰ to 3.6‰. The O isotopic characteristics indicate that the ore-forming fluids for the Khalyfehlou deposit was meteoric-formational water.This study suggests that mineralization at the Khalyfehlou deposit is similar to cordilleran vein-type deposits.
S. A. Majidi; M. Lotfi; M. H. Emami; N. Nezafati
Abstract
The metallogenic zone of Bafgh-Saghand in central Iran hosts huge low-titanium iron oxide-apatite (IOA) deposits (also called Kiruna type iron deposits) with more than 1500 Million tons grading 55% iron. The genesis of these deposits including Chadormalu, Choghart, She-Chahun, and Esfordi has long been ...
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The metallogenic zone of Bafgh-Saghand in central Iran hosts huge low-titanium iron oxide-apatite (IOA) deposits (also called Kiruna type iron deposits) with more than 1500 Million tons grading 55% iron. The genesis of these deposits including Chadormalu, Choghart, She-Chahun, and Esfordi has long been a subject of debate. In this regard, several hypotheses such as magmatic, hydrothermal, carbonatititc, BIF, and sedimentary-exhalative have been proposed so far. In this study, 20samples of the magnetite ore from the deposits of Chadormalu, Choghart, She-Chahun, and Esfordi were selected and analyzed for their oxygen isotope values. Based on the analyses results, the variations of δ18O values in the deposits are meaningful and result from the characteristics of the ore forming processes involved. The δ18O values of the analyzed magnetite samples range from -0.1 to +2.2‰ and indicate the role of both orthomagmatic (>0.9‰) and hydrothermal (<0.9‰) processes in the formation of these deposits. On the other hand, the values lower than +0.3‰ can be attributed to secondary oxidation or hydrothermal processes and/or a combination of both. The oxygen isotope data of the investigated samples are identical to the deposits such as El Laco of Chile, Kiruna and Grängesberg of Sweden, and Zhibo and Chagangnuoer of China with a magmatic-hydrothermal genesis. According to the geological and analytical evidence obtained from the iron oxide-apatite deposits of the Bafgh-Saghand area, first a tonalite-trondhjemite-granodiorite, diorite, and granite magmatism related to a continental margin subduction at 533 to 525Ma has caused a magmatic mineralization of iron in the area, while a later hydrothermal process related to an alkaline intrusion (syenite and monzosyentie) has caused a hydrothermal mineralization. Therefore a magmatic-hydrothermal source can be suggested for the formation of the low-titanium iron oxide-apatite deposits of the Bafgh-Saghand area.
M Norouzi; M. Lotfi; M. H. Emami; H. Jamali; A. Abedini
Abstract
Mesgarabad area is located in ~10 km southeast of Tehran, the Central- Alborz structural zone (CASZ) of Iran. The rock units exposed in the area consist of Eocene volcanics, volcano-sedimentary and sedimentary rocks intruded by post upper Eocene granodiorite to quartz monzo-diorite. These subvolcanic ...
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Mesgarabad area is located in ~10 km southeast of Tehran, the Central- Alborz structural zone (CASZ) of Iran. The rock units exposed in the area consist of Eocene volcanics, volcano-sedimentary and sedimentary rocks intruded by post upper Eocene granodiorite to quartz monzo-diorite. These subvolcanic intrusive bodies show porphyroid to microgranular textures and have calc-alkaline magmatic nature. These bodies produced hydrothermal fluids causing extensive alteration zones developed along the Se-Darreh-e-Bozorg strike-slip fault. The effects of hydrothermal fluids on the entire Eocene rock units and subvolcanic intrusive bodies are remarkable. The main alterations are silicification, sericitization, chloritization, epidotizaton, actinolitization, argillization, carbonatization, and alunitization-jarositization, which provided suitable physico-chemical conditions for ore-mineralization. The penetration of subvolcanic intrusive bodies into the Eocene volcanics, volcano-sedimentary and sedimentary rocks brought about skarn mineralization and epithermal barite veins. Microscopic studies and advanced analysis showed that the principal mineral phases in the epithermal zones are magnetite, pyrite, chalcopyrite, bornite, chalcocite, barite, Cu+Sn+Fe alloy, hematite, psilomelane, jacobsite, martite, geothite, and lepidochrosite. The skarnification processes occurred at two distinct stages, (1) progressive and (2) retrogressive. The pyrometasomatic anhydrous minerals such as andradite-grossularite formed during progressive stage and the hydrous minerals like epidote, chlorite, tremolite- actinolite, calcite, quartz, pyrite, chalcopyrite and chalcocite were developed during retrogressive stage. Fluid inclusion studies on primary aqueous inclusions trapped in barite crystals revealed fluid that mixing of two fluids having different physico-chemical conditions played an important role for ore deposition.
S. A. Majidi; M. Lotfi; M. H. Emami; N. Nezafati
Abstract
The Origin of Iron Oxide-Apatite deposits (IOA) with low Ti or Kiruna type deposits has long been a matter of debate. In this case, several provenances have been proposed for these deposits which include: magmatic, magmatic-hydrothermal, hydrothermal, banded iron formations, and sedimentary-exhalative. ...
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The Origin of Iron Oxide-Apatite deposits (IOA) with low Ti or Kiruna type deposits has long been a matter of debate. In this case, several provenances have been proposed for these deposits which include: magmatic, magmatic-hydrothermal, hydrothermal, banded iron formations, and sedimentary-exhalative. Bafq-Saghand metallogenic zone is located in central Iran and hosts several large IOA type deposits including Chadormalu, Choghart, Se-Chahun, and Esfordi with nearly ~1500 mt ore with an average grade of 55%. Mineralization of REE-rich apatite is very common in these deposits, an issue that could be utilized for the study of their genesis. Fifteen apatite samples from the deposits of Chadormalu, Choghart, Se-Chahun, and Esfordi were taken and analyzed using LA ICP-MS. According to the geochemical analysis, the apatite of the abovemnetioned deposits show high enrichment of Y, Na, and Si, while very low content of Cl. Total REE content varies from 0.36-2.25% in which the LREE show an enrichment indicating strongly fractionation from HREE. Strong negative Eu anomaly (0.69-0.256) is observed. Sr and Y contents in apatites are 165-365 and 743-1410 ppm, respectively. The Fe-OH-Cl diagram shows that apatites is situated in the Hydroxil-fluoroapatite domain. The results show that these deposits are similar to those of IOA type deposits (e.g. Kiruna, El Laco, Abagong, Avnik, etc.). Apatite mineralization is unlikely related to carbonatitic magmatism, but situated in the Kiruna type and mafic rocks domain. The main mineralization event was likely related to tonalite-trondhjemite-granodiorite (TTG) and diorite-granite of arc magmatism (525-532 Ma) which were intruded into the Cambrian volcano sedimentary units (as country rock). Then the hydrothermal processes following alkaline intrusion (syenite and monzosyenite) led to mineralization. In general, the iron oxide-apatite (IOA) mineralization with low Ti has occurred through the magmatic-hydrothermal processes in the Bafgh-Saghand zone.
Economic Geology
A. Baharvandi; M. Lotfi; M. Ghaderi; M. R. Jafari; H. A. Tajeddin
Abstract
Shekarbeig barite deposit is located 46 km southwest of Mahabad in northwestern part of the Sanandaj-Sirjan zone. The outcropped rock units in the area are Late Protrozoic metamorphosed volcano-sedimentary rocks, equivalent to Kahar Formation. The main ore mineral occurs as stratiform barite lenses in ...
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Shekarbeig barite deposit is located 46 km southwest of Mahabad in northwestern part of the Sanandaj-Sirjan zone. The outcropped rock units in the area are Late Protrozoic metamorphosed volcano-sedimentary rocks, equivalent to Kahar Formation. The main ore mineral occurs as stratiform barite lenses in three horizons accompanied by sulfide minerals as massive and/or parallel bands within metamorphosed rhyolitic tuffs (metatuff). The deposit footwall is composed of phyllite and slate crosscut by silicic and sulfide-bearing barite veins and veinlets (stringer zone). Primary minerals in the ore are mainly barite, pyrite, marcasite, chalcopyrite and bornite and secondary minerals are chalcocite, covellite, malachite, siderite, goethite, hematite and other iron hydroxides. Gangue minerals include quartz, sericite, calcite, dolomite, feldspar and chlorite. In terms of metallic ores, the Shekarbeig deposit does not vary much having only pyrite and chalcopyrite. Types of fluid inclusions in the Shekarbeig deposit are two-phase liquid-vapour (LV), mono-phase vapour and mono-phase liquid; two-phase liquid-vapour being the dominant type in both stringer and stratiform parts. Sulfur isotope data indicate that seawater was the main mineralizing fluid for Shekarbeig mineralization. These data suggest that complete reduction of recent seawater sulfate and the rate of mixing of hydrothermal solution with cold waters in deep parts of the basin may result in precipitation of large amount of sulfides in the stringer and stratifrom zones. On the other hand, partial reduction of recent seawater sulfates provided required sulfur for the deposition of barite. Geological evidence, evaluation, lithostratigraphy, mineralization geometry and the results of fluid inclusion and sulfur isotope studies for samples from the Shekarbeig deposit indicate derivation of the hydrothermal fluids of low salinity and moderate temperature from seawater and circulation and upward movement by a heating source (probably subvolcanic intrusions) and finally cooling and deposition of the fluids as sulfate and sulfide on the sea floor due to mixing with seawater, similar to massive sulfide Kuroko-type deposits.
M Bahrampour; M Lotfi; A Akbarpour; E Bahrampour
Abstract
The Chahmora copper deposit is located at South west of Shahrud, within the Torud-Chahshirin magmatic arc. Mineralization in the Chahmora area occurred within volcanic units of Eocene. Based on field and laboratory investigations, the outcropped rocks in the Chahmora deposit are andesite, ...
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The Chahmora copper deposit is located at South west of Shahrud, within the Torud-Chahshirin magmatic arc. Mineralization in the Chahmora area occurred within volcanic units of Eocene. Based on field and laboratory investigations, the outcropped rocks in the Chahmora deposit are andesite, andesite – basalt, trachy andesite, trachy andesite basalt and several small exposures of pyroclastic rocks such as agglomerate. Basic to intermediate sub-volcanic bodies intruded Eocene volcanic-pyroclastic sequences. The rocks are high-K, calc-alkaline to shoshonitic in nature, and are formed at a magmatic arc setting in a subduction zone. The host rocks have been affected by silicification, carbonatization, sericitization and chloritization. The textures and structures of mineralization are vein-veinlet, replacement and open space filling. According to the mineralography studies, main minerals of copper are chalcocite, chalcopyrite, covellite, digenite, cuprite, malachite and rare native copper together with hematite. Chalcocite and malachite are the most abundant minerals. Geochemical studies indicate that copper has only relative correlation with silver (R=0.894) and arsenic (R=0.520).Since silver has not founded as an independent crystalline phase, therefore copper was replaced by silver in chalcocite. . Fluid inclusion studies on trapped fluids in quartz and calcite show average homogenization temperature of 200-220ºC and fluids salinity degree of 0/97-1/37 and 3/67-4/07 %wt NaCl. Copper mineralization in the Chahmora deposit has similarities in mineralogy, host rock, texture, structure and geometry with manto-type and volcanic red bed copper deposits.
S Aghajani Marsa; M Emami; M Lotfi; k Gholizadeh; M Ghasemi Siani
Abstract
The mineralized veins at Nikuyeh are located south of the Tarom-Hashtjin metallogenic province in Alborz-Azarbayejan belt (West Alborz). Rhyodacite and andesite/andesitic basalt volcanic rocks are hosting the vein mineralization in the Nikuyeh ore district. Hydrothermal alteration in host rocks consists ...
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The mineralized veins at Nikuyeh are located south of the Tarom-Hashtjin metallogenic province in Alborz-Azarbayejan belt (West Alborz). Rhyodacite and andesite/andesitic basalt volcanic rocks are hosting the vein mineralization in the Nikuyeh ore district. Hydrothermal alteration in host rocks consists of propylitic, sericitic, argillic and silicic. Mineralization in Nikuyeh occurs in both hypogene and supergene forms in three stages: early stage includes pyrite, magnetite, chalcopyrite and bornite; middle stage includes galena, sphalerite and minor chalcopyrite, and late stage includes malachite, cerussite, covellite, hematite and goethite. Fluid inclusion studies on quartz and calcite show homogenization temperatures ranging between 185°C to 312°C and 133°C to 251°C, respectively. The salinities range from 0.5 to 5.5 wt% NaCl eq. in quartz and 0.3 to 5.4 wt% NaCl eq. in calcite. Boiling is supported by the occurrence of coexisting vapor-rich and liquid-rich inclusions, hydrothermal breccias, microcrystalline quartz, chalcedony and bladed calcite. Boiling and cooling are considered as the main mechanisms for ore deposition. Ore mineralogy, alteration assemblages and fluid inclusion data allow mineralization in Nikuyeh ore district to be classified as low sulfidation epithermal type.
M Fereidoni; M Lotfi; N Rashid nejad; M Rashidi
Abstract
The Qalikuh area,~35 km southwest of Aliqudarz, contains oil shale deposits in Garue and Sargelu formations(Jurassic-Cretaceous). Some 20 samples across two sections(Charun3-Deh ye Qali3) were selected and analyzed(Rock Eval – ICP – XRD – XRF) to study organic and mineral parameters(to ...
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The Qalikuh area,~35 km southwest of Aliqudarz, contains oil shale deposits in Garue and Sargelu formations(Jurassic-Cretaceous). Some 20 samples across two sections(Charun3-Deh ye Qali3) were selected and analyzed(Rock Eval – ICP – XRD – XRF) to study organic and mineral parameters(to determine type of organic material and kerogen, total organic carbon, thermal evolution, concentration, and classification of elements and minerals) and to model the relations between these parameters. The Qalikuh oil shale has a great potential for oil production with high levels of TOC (13.5 wt%), type 2 kerogen, low thermal maturity. However Qalikuh oil shale has metallic and nonmetallic element anomalies and high concentrations of strategic elements compared to Clark values. Dendritic diagrams suggest variable origins for elements and minerals in the samples. Some are associated with development of organic materials, TOC parameters, Resin and Asphaltene, and some are associated with clastic materials, aluminosilicates and source rock weathering.
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.
Z Miriyan; M Lotfi; A.A Shabani; M.A.A Mokhtari; E Haj Molla Ali
Abstract
The Kharengun area is located in the Yazd province, Central Iran, 130 km east of Yazd city and 65 km northeast of Bafq city. Mineralization in Kharengun area occurred within calcic and dolomitic units of the Rizou Formation (equivalent to Soltaniyeh Formation) of upper Precambrian- lower Cambrian age. ...
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The Kharengun area is located in the Yazd province, Central Iran, 130 km east of Yazd city and 65 km northeast of Bafq city. Mineralization in Kharengun area occurred within calcic and dolomitic units of the Rizou Formation (equivalent to Soltaniyeh Formation) of upper Precambrian- lower Cambrian age. The ore minerals of this deposit includes smithsonite and hemimorphite, that is stratabound and formed epigenetically along layers and laminations of carbonate host rocks. The maximum grade of zinc in samples taken from the study area exceeds 36% and geochemical studies indicate significant absence of Pb along with Zn in this area. Therefore, the Kharengun mineralization is a monomineral Zn zone.The fluid inclusion microthermometry investments explain the role of meteoric waters in generation of this deposit. The homogenization temperatures and salinity of the inclusions show the similarity between these fluids and the solutions responsiblefor the development of epithermal deposits.The Zn mineralization present in this zone belongs to the nonsulfide supergene deposit class, and a mixture of wallrock replacement and direct replacement subclasses.
H Alizadeh; M Aryan; M Lotfi; M Ghorashi; M Ghorbani
Abstract
The Dehaj-Sardoiyeh Belt, which is a part of the Urmia-Dokhtar Volcanic-Plutonic Zone, consists of several economic porphyry copper deposits. This area is located on the right lateral shear zone surrounded by the Rafsanjan fault in the north and the Shahr-e Babak fault in the south. In this research, ...
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The Dehaj-Sardoiyeh Belt, which is a part of the Urmia-Dokhtar Volcanic-Plutonic Zone, consists of several economic porphyry copper deposits. This area is located on the right lateral shear zone surrounded by the Rafsanjan fault in the north and the Shahr-e Babak fault in the south. In this research, spatial relationship among sixteen porphyry copper deposits, faults and fractures was studied. The results show a strong relationship between the Photo lineament factor and location of the porphyry copper deposits. The direction of lineament factor (d/D) was found to be highly correlated with the location of porphyry deposits. The results can be used in exploring preliminary porphyry deposits with regard to the geometry and mechanisms of the faults and fractures.
M Khalajmasoumi; M Lotfi; A Memar Kuchebagh; A Khakzad; P Afzal
Abstract
The studied area in the Saghand fifth anomaly is located in the Bafgh-Posht-e-Badam metalogeny belt in the Central Iran zone. Uranium, Thorium and Rare Earth Elements mineralization are hydrothermal and metasomatism type related to area intrusion bodies (Granite and Gabbro available in the north of study ...
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The studied area in the Saghand fifth anomaly is located in the Bafgh-Posht-e-Badam metalogeny belt in the Central Iran zone. Uranium, Thorium and Rare Earth Elements mineralization are hydrothermal and metasomatism type related to area intrusion bodies (Granite and Gabbro available in the north of study area). Uranium of hydrothermal type followed by deep fracture systems and concentrated around the magnetite bodies. The reasons are geochemical environment and alkaline metasomatism of Uranium - Thorium and Rare Earth Elements produced under an important metalogeny cycle in the Central Iran and studied area. The tudied area in special case, Cerium and Yttrium show positive correlation with mineralization of radioactive materials (Uranium – Thorium). Considering the genetic relationship between these elements (Cerium and Yttrium), popular separation of anomalous elements carried out by using classical statistical methods for lithogeochemical data and calculated statistical parameters. Then, the frequency distribution histograms along the calculation were plotted and consequently, the separation of anomalous element populations carried out. High positive correlation among the radioactive elements (U & Th) and Rare Earth Elements such as Cerium and Yttrium indicated that their mineralization phase generated from the same origin. Compilation of geochemical and geological rock unit maps designated that the radioactive ore mineralization was controlled by metasomatism, which produced different types of albite metasomatite, amphibole metasomatite, and albite-amphibole metasomatite from the rocks of pyroclastics, diabase, dacite and gabbro in the area. Uranium and Thorium anomalies calculated by classical statistical methods are mostly distributed in the west, southwest, and central part of the area, but in the central part the Th-intensity relatively was stronger than the Uranium. The anomaly trend for Cerium and Yttrium are the same as the Uranium and Thorium, but Yttrium anomaly in the central part is more intensive than the others.
S.T Delavar; I Rasa; M Lotfi; G Borg; N Rashidnejad Omran; P Afzal
Abstract
Tangedezan Zn-Pb deposit is located in 22 km west of Booeen Miandasht city, in western part of Isfahan province and in Malayer–Isfahan Pb-Zn mineralization belt. This deposit is one of the stratabound deposits in a Jurassic-Cretaceous carbonate sequence. Two main ore body geometries have been recognized ...
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Tangedezan Zn-Pb deposit is located in 22 km west of Booeen Miandasht city, in western part of Isfahan province and in Malayer–Isfahan Pb-Zn mineralization belt. This deposit is one of the stratabound deposits in a Jurassic-Cretaceous carbonate sequence. Two main ore body geometries have been recognized in the deposit: 1-layers and lenses, concordant with layering; and 2-discordant secondary forms along the fractures. In Tangedezan deposit two mineralized carbonate facies have been distinguished: 1- dolomitic limestone facies (Microsparite) containing three major mineralization horizons with simple ore mineral paragenesis such as galena, sphalerite and pyrite replacing the host rock and filling the porosities and fractures; and 2- crystallized argillaceous limestone facies with very weak Zn-Pb mineralization in disseminated form. The deposit includes two parts of supergene in surface and sulfides in depth. The simple ore paragenesis comprises of hemimorphite, smithsonite, cerussite, galena, sphalerite and pyrite. Ag and Cd elements have noticeable grade and could be contemplated as by product. All accomplished investigations and evidences such as geological characteristics, mineralized facies, supergene and sulfide development, ore body geometry, ore minerals paragenesis, texture and structures in different scale, existing alterations specially dolomitization and lithogeochemical studies all reveal that Tangedezan deposit is a Zn-Pb Mississippi Valley Type (MVT) deposit.
M. Lotfi; S.F Sadjadi AleHashem; M. H. Emami
Abstract
Boznein manganese deposit is located in 25 km south-southwest of Ardestan, part of Urmiyeh-Dokhtar magmatic belt. The main units in the studied area are volcanic-pyroclastic sequences & intrusive bodies of middle Eocene-lower Oligocene. Porphyroid rhyolitic dome (upper Eocene-lower Oligocene) is ...
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Boznein manganese deposit is located in 25 km south-southwest of Ardestan, part of Urmiyeh-Dokhtar magmatic belt. The main units in the studied area are volcanic-pyroclastic sequences & intrusive bodies of middle Eocene-lower Oligocene. Porphyroid rhyolitic dome (upper Eocene-lower Oligocene) is host rock of economic Mn mineralization. The mineralization occurred as veins trending mostly NE-SW of interrupted total length of 1.5 m width at two active mines of 1 and 2. Exploitable reserve of the mine is estimated to be 60,000 tons of an average grade of 50.18% MnO. The main Mn ore minerals including braunite, bixbyite, hausmanite, spessartine rhodochrosite, manganite, pyrolusite, psillomelane, cryptomelane that by As and Cu minerals. Ores shows massive, microcrystalline, euhedral, colloform, colloidal, bubble form, acicular, tabular, veinlet, breccia, stockwork and residual textures. In base of ore samples geochemical characteristics and comparison with studied Mn types and deposits, indicate a good match with hydrothermal Mn-deposits. In base of mineralization form, host rock petrography and age, ore texture and structure, mineralogy, geochemical characteristics and genetic controlling factors, the Boznein deposit shows similarities with epithermal Mn-deposit. Non-economic syngenetic Mn-mineralization in the unit older than rhyolitic dome can be considered as the possible source of the Mn. Contemporaneous with intrusion rhyolitic dome, Mn concentration led to high grade epigenetic Mn vein in surrounding porphyroid rhyolitic dome.
A. Keynezhad; M. Pourkermani; M. Arian; A. Saeedi; M. Lotfi
Abstract
Detailed geological and structural analysis of north of Torud-Moalleman area (Central Iran), between Anjilu fault in north and Torud fault in the south, led to tectonic elements of this limit such as fractures and relative of their mechanism with left lateral sheared zone of two main faults. This study ...
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Detailed geological and structural analysis of north of Torud-Moalleman area (Central Iran), between Anjilu fault in north and Torud fault in the south, led to tectonic elements of this limit such as fractures and relative of their mechanism with left lateral sheared zone of two main faults. This study provides a movement system of Chalu, Gandi and Hafez faults in this shear zone. On the basis of kinematics findings and using general methods of fault slip analysis (orientation of slip plane, slip vector, shape of stress ellipsoid and angle of internal friction) region stress field were calculated after determining the angle of internal friction for each one of fault limits. Then, the main stress orientation determinates for combination data that values of ،وwere 195/10, 339/78 and 104/07 respectively. The shape of stress ellipsoid was defined on the basis of shape factor, [R= (-) / (-)], (Angelier, 1975). The R-value for whole studied regions was about 0.5 and deformation type was mainly left lateral transpressional with reverse component. Such results are evident from N-NE (N195) trending in the region and northward movement of the lithosphere. These finding are in line with field research results of fractures, faults and mechanism in this general shear zone.
F. Ehya; M. Lotfi
Abstract
The Sarfaryab bauxite deposits occur in karstic depressions at the top of the limestones of the Cenomanian to Lower Turonian Sarvak Formation, which are overlain by the limestones of the Santonian Ilam Formation. In order to determine the possible source rocks of the Sarfaryab bauxite deposits, a few ...
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The Sarfaryab bauxite deposits occur in karstic depressions at the top of the limestones of the Cenomanian to Lower Turonian Sarvak Formation, which are overlain by the limestones of the Santonian Ilam Formation. In order to determine the possible source rocks of the Sarfaryab bauxite deposits, a few samples were collected from Sarvak Formation, terra rossa and bauxite ore and geochemically and geostatistically analyzed. Plots of chemical data and correlation coefficients show that Al, Ti, Zr, Nb, Cr and V were immobile during the bauxitization process. In the scatter diagrams of Zr and TiO2 versus Al2O3, regression lines pass through the origin and terra rossa falls between the Sarvak Formation and bauxite. Based on this research, it can be stated that the source rock of the Sarfaryab bauxite deposits is the Sarvak Formation and terra rossa is an intermediate product during limestone-bauxite transformation. Post-Turonian uplift had exposed recently deposited limestones of the Sarvak Formation to karst weathering, and a layer of argillaceous debris accumulated on its surface and was partly converted to bauxite. Subsidence followed, and the bauxite was preserved by the deposition of limestones of the Ilam Formation. Uplift in Pliocene time, with ensuing erosion, exposed the bauxite deposits to their present situation.
Ghodratollah Rostami Paydar; M. Lotfi; M. Ghaderi; A. Amiri; M. Vossoughi-Abedini
Abstract
Baba-Ali and Galali iron deposits in west of Hamedan are emplaced within the Songhor volcano-sedimentary sequence of Sanandaj-Sirjan geological-structural zone. Mineralography and SEM-EDAX analyses on magnetite iron ores at both deposits for better understanding of mineralogy and crystal-chemistry of ...
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Baba-Ali and Galali iron deposits in west of Hamedan are emplaced within the Songhor volcano-sedimentary sequence of Sanandaj-Sirjan geological-structural zone. Mineralography and SEM-EDAX analyses on magnetite iron ores at both deposits for better understanding of mineralogy and crystal-chemistry of the ores have shown some interesting results. Studies on concentrations of some trace elements such as V, Co, Ni, Cu, Cr, Ti, Au, PGE as well as S and P impurities in the ore indicate that only some of the primary pyrites have considerable concentrations of Pt. It seems that other generations of pyrite and magnetite are depleted in these trace elements. Late stage hydrothermal fluids that lead to mineralization of pyrite in calcite-quartz gangue veins, have also been impotant for gold mineralization and pyrite has actually acted as a favorable carrier for Au. Detection of abundant phlogopite and trace element concentration patterns at Galali iron ore have strengthened volcanogenic magnesian skarn hypothesis.
