Economic Geology
Leila Amini; Mohammad Maanijou
Abstract
One of the common processes that lead to the formation of and enrichment of precious metal deposits is boiling. The existence of a spatial relation between fluid boiling and deposition of precious metals is a valuable tool in exploration of epithermal deposits. Therefore, investigating the occurrence ...
Read More
One of the common processes that lead to the formation of and enrichment of precious metal deposits is boiling. The existence of a spatial relation between fluid boiling and deposition of precious metals is a valuable tool in exploration of epithermal deposits. Therefore, investigating the occurrence of this process will be able to predict the continuation of exploration trend. ChahMorad epithermal deposit is 75km northwest of Bazman in the Sistan-and-Baluchistan Provinces and is in the Makran-Chagai Magmatic Arc southeast of Iran. The mineralization in the ChahMorad deposit occurred in 3 stage and in quartz veins that exist between the altered argillic alteration zone and dacite and rhyodacite sub-volcanic rocks. Textural mineralogical and fluid inclusions studies indicate the occurrence of the boiling process in this deposit. The most important kinds of evidence for the occurrence of this process are (a)the presence of adularia, (b) platy calcite texture, (c)breccia, crustiform-colloform textures, (d)different liquid-vapor ratios of fluid inclusions, (e)the increase in the salinity of fluid inclusions with the decrease in homogenization temperatures, (f)the coexistence of fluid inclusions with different salinities and (g) coexisting liquid single-phase fluid inclusions with vapor fluid inclusions single-phase. Therefore, existing of boiling is confirmed in the ChahMorad deposit.
Economic Geology
Mohsen Rezaei; Alireza Zarasvandi; Sima Basious
Abstract
Iju porphyry deposit is associated with the emplacement of Miocene tonalite-granodiorite intrusions (zircon U/Pb dating; 9.27±0.50) within Eocene volcanic and pyroclastic sequences including andesite, basaltic andesite, trachyandesite, andesitic breccias, tuffaceous breccias, and agglomerate. ...
Read More
Iju porphyry deposit is associated with the emplacement of Miocene tonalite-granodiorite intrusions (zircon U/Pb dating; 9.27±0.50) within Eocene volcanic and pyroclastic sequences including andesite, basaltic andesite, trachyandesite, andesitic breccias, tuffaceous breccias, and agglomerate. In this study, occurrence and chemistry of magnetites in the potassic alteration of Iju deposit were assessed using EMPA analysis. The findings imply for a limited occurrence of magnetite as fine-grained disseminated and/or product of biotite chloritization. Magnetites associated with potassic alteration of Iju deposit don’t show hematite intergrowth (as martitizied margin) and anhydrite paragenesis, indicating the lack of high oxygen fugacity (near magnetite-hematite buffers; ~ΔFMQ+4) during the magnetite crystallization in the potassic alteration. Studied magnetites are high temperature (>500 °C) and according to the Mg + Al + Si contents crystallized under low rate of fluid rock interaction. These evidences accompanied with the absence of reequilibration processes could imply for the lack of repeated stages of hydrothermal fluid exsolving during the evolution of potassic alteration in the in the Iju deposit. Additionally, results represent that there are a considerable values of Ga (average; 0.015 wt. %) in the studied magnetites providing insights into the presence of unseen exploration potentials associated with porphyry Cu deposits of UDMB.
Economic Geology
Alireza Zarasvandi; Mohsen Rezaei; Mansour Adelpour; Hadis Parvaneh
Abstract
Parkam (Sara) and Abdar porphyry Cu deposits containing mainly dioritic and quartz dioritic stocks are located in the southern part of Urumieh-Dokhtar Magmatic Belt (UDMB). In the Parkam deposit, alterations such as potassic, potassic-phyllic, biotitic, phyllic, argillic and propylitic have been identified, ...
Read More
Parkam (Sara) and Abdar porphyry Cu deposits containing mainly dioritic and quartz dioritic stocks are located in the southern part of Urumieh-Dokhtar Magmatic Belt (UDMB). In the Parkam deposit, alterations such as potassic, potassic-phyllic, biotitic, phyllic, argillic and propylitic have been identified, while Abdar deposit is characterized by the limited extent of potassic alteration with widespread occurrence of phyllic alteration. The aim of this study is to characterize the phyllic alteration using sericite and sulfide (i.e., pyrite and chalcopyrite) chemistry. In this way representative phyllic alteration samples were analyzed using Electron Microprobe Analysis (EMPA). Results imply for higher concentrations of Zn, Ag, Au, and as in the chalcopyrite samples (averages in wt. %; 0.07, 0.007, 0.012, and 0.043; respectively). Comparably, pyrite samples exhibit higher concentrations of Re, Te, Co, and Mo (averages in wt. %; 0.01, 0.003, 0.09, 0.07; respectively. Among this, gold concentration in the pyrite samples of studied deposits is analogous to those reported previously for Meiduk porphyry Cu-Mo systems wherein gold occurs as inclusions, and/or nanoparticles (probably as Au0 or Au-telluride). In the both deposits, fine-grained micas are K-rich. Additionally, sericite samples exhibit an increasing trend of Si with Fe2+, Mg2+, and Al3+ substitution in the octahedral sites confirming the changes to celedontie - endmember. In accordance with other mineralized porphyry systems (i.e., Copper Cliff and Copper Flat deposits), most of the data follow the trend of ideal tschermak substitution occurring by the increasing of positive charges in the tetrahedral site of white mica owing to the increasing of Si substitution.
Economic Geology
Sholeh Malekshahi; Masoumeh Khalajmasoumi; Hadi Mohammad- Doost; Mona Sojdehee; Shahrzad Aboutorab
Abstract
The Sarkuh Porphyry Copper deposit is located about 6 km southwest of Sarcheshmeh porphyry copper deposit. Alterations in the region include advanced potassic, propylitic, phyllic and argillic. Copper mineralization is mainly associated with porphyry granodiorite mass. Minerals include chalcopyrite, ...
Read More
The Sarkuh Porphyry Copper deposit is located about 6 km southwest of Sarcheshmeh porphyry copper deposit. Alterations in the region include advanced potassic, propylitic, phyllic and argillic. Copper mineralization is mainly associated with porphyry granodiorite mass. Minerals include chalcopyrite, pyrite, magnetite and some molybdenite. Fluid inclusion studies were performed on quartz from the sulfide viens of the potassic fraction and showed that the main mineralization phase was present with a homogenization temperature between 250 and 527 ° C, salinity between 13.6 and 52.9 wt٪ NaCl, has a high salinity in Sarkuh deposit (Orthomagmatic phase and hypogene mineralization). The homogenization temperature in the late stages of the receding phase (convective phase and the influence of atmospheric waters in the hydrothermal cycle) is around 132 to 165 degrees Celsius and its salinity is 0.005 to 4.74% equivalent to the weight of NaCl. The observed salinity variation can be attributed to the boiling event. The investigation of sulfur isotope composition on pyrite and chalcopyrite minerals in Sarkoh deposit was between +1 and 2.7‰, which indicates the magmatic source of sulfur. The stable oxygen isotope data on quartz veins, show positive range between 7.6 to +9.3‰ with an average of +8.5, indicates a magmatic source for hydrothermal fluids. Also, due to the limited range of sulfur isotopic composition, it can be concluded that the isotopic composition of sulfur has not undergone changes or contamination by other sources of sulfur, or the mixing of magmatic fluid with other sources has been very insignificant. Isotopic thermometry shows the temperature of 315°C and 476°C for the pair of pyrite-chalcopyrite minerals.
Economic Geology
Maryam Khosravi; Wenchao Yu; Jintao Zhou
Abstract
The Gano bauxite deposit is located 90 km northeast of Semnan city in the eastern Alborz Mountains, northern Iran. The bauxite ores occur as stratiform discrete lenses with a length of 6 km and thickness of 2–20 m along the contact between carbonates of the Elika Formation and shale, sandstone, ...
Read More
The Gano bauxite deposit is located 90 km northeast of Semnan city in the eastern Alborz Mountains, northern Iran. The bauxite ores occur as stratiform discrete lenses with a length of 6 km and thickness of 2–20 m along the contact between carbonates of the Elika Formation and shale, sandstone, siltstone, and coal of the Shemshak Formation. Mineralogical analyses revealed that the bauxite ores consist of diaspore, hematite, kaolinite, chlorite, anatase, illite, zunyite, goethite, quartz, and dolomite minerals. Fluctuations of the groundwater table level, acidic atmospheric waters, and an increase in pH of the weathering solutions close to carbonate bedrocks played an important role in the concentration of Fe-poor ores in the upper parts and Fe-rich ores in the lower parts of the studied profile. An increase in oxidation, the possible presentence of secondary phosphate minerals, fluctuations of the groundwater table level, and the role of carbonate bedrock as an active buffer played an important role in the extent of Ce anomaly in the ores (0.79–12.25). The pH variations of weathering solutions, fluctuations of the groundwater table level, the role of carbonate bedrock as a geochemical barrier, and simultaneous precipitation of Fe-bearing minerals and preferential scavenging of LREE(La–Eu) by hematite played an important role in the distribution and fractionation of rare earth elements in the bauxite ores. According to geochemical considerations (Eu/Eu* vs. TiO2/Al2O3 and Sm/Nd bivariate diagrams), the Gano bauxite deposit probably derived from the weathering of intermediate igneous rocks.
Economic Geology
Shohreh Hassanpour; Susan Ebrahimi
Abstract
Astmal deposit is located in the northwest of Iran and is structurally located in the Arasbaran Magmatic zone. Skarn mineralization related to the Eocene-Oligocene granodiorite rocks which have been permeated to the Upper Cretaceous rocks. Mineralization has formed in the exoskarn zone, and the metasomatic ...
Read More
Astmal deposit is located in the northwest of Iran and is structurally located in the Arasbaran Magmatic zone. Skarn mineralization related to the Eocene-Oligocene granodiorite rocks which have been permeated to the Upper Cretaceous rocks. Mineralization has formed in the exoskarn zone, and the metasomatic process has started immediately after the penetration of the granodiorite into the limestone. Significant amounts of Si, Mg, and Fe elements lead to the development of anhydrous calc-silicate minerals with medium to coarse grains, and also significant amounts of Cu, Fe elements along with volatile substances such as CO2, H2S are added to the skarn system. As a result, hydrated calcsilicates (epidote, tremolite, and actinolite), sulfides (pyrite and chalcopyrite), oxides (magnetite and hematite) and carbonates (calcite) have been replaced anhydrous calcsilicates. The results of δ34S isotope analysis on pyrite and chalcopyrite ores are in the range of -1.8 to +6.1 ‰, which indicates the magmatic source of sulfide. Also, the results of δ18O and δD isotope data on magnetite, sericite and epidote minerals, which are in the range of -56 to -73 ‰ for hydrogen and -0.5 to +6.8 ‰ for oxygen, indicate a mixture of magmatic fluids associated to the small amounts of meteoric fluids.
Economic Geology
Maryam Emami Jafari; Saeed Alirezaei; Iraj Rasa; Jochen Kolb
Abstract
The Hired gold deposit in the Lut block, East Iran, is closely associated with an intermediate-mafic intrusive complex consisting of granodiorite to diorite, hornblende quartz-monzonite, and gabbro-diorite intruded into Eocene volcanic rocks. The intrusions are distinguished by high contents of CaO, ...
Read More
The Hired gold deposit in the Lut block, East Iran, is closely associated with an intermediate-mafic intrusive complex consisting of granodiorite to diorite, hornblende quartz-monzonite, and gabbro-diorite intruded into Eocene volcanic rocks. The intrusions are distinguished by high contents of CaO, FeOt, and MgO, and rather low K2O+Na2O implying they crystallized from weakly differentiated magmas. This subject, and the relatively high Mg# (36.36 to 52.32) imply the involvement of a mantle source in the production of the parent magma. The intrusions are metaluminous, calc-alkaline to high-K calc-alkaline, and distinguished by the occurrence of ilmenite as an accessory mineral. Mineralization occurs in veins and veinlets disseminations in the granodiorite intrusion and the volcanic rocks, closely associated with tourmaline, silicic, and carbonate alterations, and is distinguished by abundant pyrrhotite, arsenopyrite, pyrite, and minor chalcopyrite, galena and sphalerite. Gold occurs mostly as submicroscopic grains in the pyrite and arsenopyrite. The mineralogical and geochemical attributes of the intrusive complex, and the ore mineralogy, allow the Hired to be classified as a gold deposit related to reduced I-type granitoids. The reducing nature of the parent magma can be explained by introduction of reduced crustal materials into the source area, and/or assimilation of carbonaceous metasedimentary rocks.
Economic Geology
Mahdi Ghorbani- Dehnavi; Azadeh Malekzadeh -Shafaroudi; Mohammad Hassan Karimpour
Abstract
Chah-Nar Pb-Zn deposit is located south of Rutchun plain, 110 km SW Baft, within Sanandaj- Sirjan Zone. Mineralization occurs at calitic-dolomitic marble of Rutchun complex as epigenetic with structural control. Paragenetic minerals are galena and minor sphalerite and pyrite associated with ...
Read More
Chah-Nar Pb-Zn deposit is located south of Rutchun plain, 110 km SW Baft, within Sanandaj- Sirjan Zone. Mineralization occurs at calitic-dolomitic marble of Rutchun complex as epigenetic with structural control. Paragenetic minerals are galena and minor sphalerite and pyrite associated with quartz, and minor calcite and dolomite, as gangue minerals. These minerals show veinlets, open space filling, breccia, and disseminated textures. Galena can be seen in the form of coarse grain crystal and cuboctahedral texture and fine grain crystal. Silicification and carbonatization are the most important alteration zones. Galena chemistry indicates galena is Ag, As, Cd and Zn -rich and Sn, Bi-poor. Sb/Bi ratio in galena is close to 3, which is indicator of low temperature deposits. Host rock type, stratabound and epigenetic mineralization, postsedimentary fault controlling, texture, ore types and gangue minerals, and lack of significant correlation between mineralization and igneous activities, chemistry of galena, indicate that Chah-Nar deposit is similar to MVT deposits, although it has some differences with this deposits type.
Economic Geology
Shiva Farangi; Zahra Alaminia; Mohammad Vahedi; Hamzeh Sadeghisorkhani
Abstract
The studied area is located in N-Sonqor and in the Sanandaj-Sirjan zone. Field relationships and petrographic evidence show that volcanic rocks of the north of Bashirabad comprise of trachydacite to trachyandesite (and altered basaltic trachyandesite) and in the south of this area, it consists of andesite ...
Read More
The studied area is located in N-Sonqor and in the Sanandaj-Sirjan zone. Field relationships and petrographic evidence show that volcanic rocks of the north of Bashirabad comprise of trachydacite to trachyandesite (and altered basaltic trachyandesite) and in the south of this area, it consists of andesite to trachyte. Their texture is mainly porphyry. Geochemical data {total abundance of (Na2O+K2O), enrichment of large lithophile ion elements and rare light earth elements) indicate that these rocks belong to the alkaline series. Spider diagrams show enrichment in LREE and depletion HREE, and parallel patterns in all volcanic samples confirm their common origin. According to modeling magmatic processes, fractional crystallization, assimilation and crustal contamination have played an important role in the magma forming the studied rocks. The discriminating diagrams the tectonic setting the Bashirabad volcanic rocks indicate their subduction-related volcanic arc that was formed in an active continental margin environment with local tensions.
Economic Geology
Hanieh Kiaei; Ahmad Kazemi-Mehrnia; Hamid Samari; Peyman Afzal; Nazanin Zaheri-Abdehvand
Abstract
The Fatehabad Cu deposit is located in the Khorasan Razavi province, 35 km SE of the Torbat-e Heydariyeh and in the Khaf-Kashmar-Bardaskan metal belt. The vein and veinlet mineralization consist of chalcopyrite, pyrite, magnetite, chalcocite, bornite, covellite, malachite and iron oxides associated with ...
Read More
The Fatehabad Cu deposit is located in the Khorasan Razavi province, 35 km SE of the Torbat-e Heydariyeh and in the Khaf-Kashmar-Bardaskan metal belt. The vein and veinlet mineralization consist of chalcopyrite, pyrite, magnetite, chalcocite, bornite, covellite, malachite and iron oxides associated with siliceous-sericite, argillite and propylitic alteration in the volcanic rocks formed parallel to the sub-faults that branch off from the Dorouneh fault. The similar pattern of REE and trace elements in the mineralized veins and associated volcanic rocks suggests an magmatic-hydrothermal origin of the ore elements. In the vein system of Fathabad district, quartz, pyrite, chalcopyrite, and magnetite veins with propylitic alteration in the early stage of mineralization, quartz, pyrite, chalcopyrite and magnetite veins with sericite alteration in the main stage of mineralization and quartz, pyrite and chalcopyrite veins were identified along with argillic and iron oxide alterations. Calcite veins along with sericite and iron oxide alterations were also identified in the late stage of mineralization. The enrichment of trace, LREEs/HREEs ratio, positive Eu anomalyand negative Ce anomaly, indicate reducing conditions and a high pH of the mineralized fluids. Fluid inclusion studies with low salinity (13.9 to 4.74 wt% NaCl eqv.) and low temperature (111 to 192 oC) indicate dilution and mixing of the sulfur- and element-rich magmatic-hydrothermal fluid with meteoric water, leading leaching and precipitation of trace, rare and copper elements. The δ34S isotopes values (-1.58 to -2.86‰) in the chalcopyrite minerals indicate the magmatic origin of sulfur. The geology, geochemistry, and fluid inclusions evidences indicate that the Fathabad Cu deposit is belong to epithermal style mineral systems.
Economic Geology
Robabeh Masoomi; Yousef Rahimsouri; Hemayat Jamali; Ali Abedini
Abstract
The aim of this research is the geochemical study of the major and trace elements of the alteration systems in the Kamar-Gov district (south of Hashtjin, Ardabil province). The rock units of the studied area include volcanic rocks with the composition of basaltic-trachy andesite to rhyolite and ...
Read More
The aim of this research is the geochemical study of the major and trace elements of the alteration systems in the Kamar-Gov district (south of Hashtjin, Ardabil province). The rock units of the studied area include volcanic rocks with the composition of basaltic-trachy andesite to rhyolite and crystal vitric-tuff with Eocene and Oligocene age. These rocks have calk alkaline and shoshonitic affinity and belong to post-collisional arc tectonic setting. In the Kamar-Gov district, the alteration zones include silicic, sericitic (quartz + muscovite + pyrite ± illite ± rutile), sericite-argillic (quartz + sericite + kaolinite + dolomite), intermediate argillic (quartz + kaolinite + illite), advanced argillic (quartz + kaolinite + alunite + diaspore ± anatase ± muscovite), and chloritic (quartz + chlorite + illite). The distribution pattern of the normalized-BSE major and trace elements and the mass change calculations (volume factor method) show that the silicic and advanced argillic alteration zones have more elemental depletion and different distribution patterns from the parent rock. However, chloritic, intermediate argillic, and sericite-argillic alterations have relatively little mass change and almost similar distribution patterns to the primary parent rock. The major elements like Ca, Mg, Al, Na, and Fe have frequently depleted. Ti shows slight depletion. K has frequently enriched. Trace elements such as Zr, Nb, Sc, and Th have mass reduction. Co, Cr, Ni, and Rb have experienced depletion and enrichment processes. Sr and V show relatively high depletion. Sb, S, and As (chiefly) have enriched. LREEs have depleted more than HREEs. Elements like Pb, Zn, and Cu only in the siliceous and sericite-argillic zone show enrichment. This research shows that factors like pH of hydrothermal fluid and primary rock-forming and secondary minerals resulting from alteration have caused differences in the behavior and concentration of elements in different alteration zones in the Kamar-Gov district.
Economic Geology
Shaghayegh Sadat Hashempour; Sajjad Maghfouri; Ebrahim Rastad
Abstract
The Goft and Mohammadabad manganese deposits are located in the southwestern part of Sabzevar, whitin the Late Cretaceous volcano-sedimentary sequences. This sequence is located inside a 100 km long folded structure with northeast-southwest trend. Mohammadabad manganese deposit located in the southeastern ...
Read More
The Goft and Mohammadabad manganese deposits are located in the southwestern part of Sabzevar, whitin the Late Cretaceous volcano-sedimentary sequences. This sequence is located inside a 100 km long folded structure with northeast-southwest trend. Mohammadabad manganese deposit located in the southeastern edge of the southern anticline in the unit 4 of regional stratigraphic column and Goft manganese deposit is occurred in the southeastern edge of the northern anticline in the first unit of the regional stratigraphic column. The host rocks of Goft and Mohammadabad deposits include red tuff and Marly tuff and limy tuff, respectively. According to geochemical studies, tectonic environment of manganese deposits in the southwest of Sabzevar is a rifting environment that has been formed in the Sabzevar back-arc basin. The rocks of the region have a wide range of basalt, rhyolite, dacite, olivine-basalt, andesite-basalt and trachy-andesite, which formed aligned with pyroclastic sediment and Late Cretaceous sedimentary units. Dacite rocks are the thickest felsic rock unit in the area. The values of major oxides, the pattern of rare earth elements (REE), and the changes in trace elements in spider diagrams indicate the bimodal and tholeiitic nature of the volcanic rocks of the region, which are deposited in extension environment with a mixed range from basalt to rhyolite.
Economic Geology
Shayan Akrami; Mohammad Ali Aliabadi; Mohammad Reza Hazareh; Abbas Askari; Tayebeh Ramezani
Abstract
Nineh Pb-Zn deposit is located in the east of the Markazi province, in the Middle to Upper Jurassic rock units of the Malayer-Esfahan metallogenic belt. Stratified and epigenetic mineralization, in the form of veins, replacement and open spaces filling, including the main minerals of galena, sphalerite ...
Read More
Nineh Pb-Zn deposit is located in the east of the Markazi province, in the Middle to Upper Jurassic rock units of the Malayer-Esfahan metallogenic belt. Stratified and epigenetic mineralization, in the form of veins, replacement and open spaces filling, including the main minerals of galena, sphalerite and barite accompanied by dolomite and siliceous alterations are observed. The microthermometry results of fluid inclusions in calcite and barite, display mean homogenization temperature of about 168.6°C and 127.3°C, and a mean salinity of 5.7 and 13.9 wt. % NaCl equiv., respectively, which indicates slight difference in their formation conditions. The homogenization temperature versus salinity diagram suggests a basinal brine fluid mineralizer and mixing and cooling processes for the mineralization. The values of δ34S in galena and sphalerite (7.5‰ to 21.5‰) of this deposit are similar to the values of δ34S in the upper Mississippi deposits, indicating the supply of sulfur during the process of thermochemical reduction of sulfate. The values of δ18OSMOW (-9.2 to -11.2‰) and δ13CPDB (0.1 to 0.5‰) of the calcite veins indicate a multi-origin of oxygen, and the origin of carbon from dissolved and remobilized marine carbonates. According to the evidence obtained during this study, the Nineh deposit can be classified as the Mississippi Valley type deposits, which was formed during the orogeny processes and the movement of basinal brine fluids.
Economic Geology
Fatemeh Esmaeili; Fardin mousivand; Mahmoud Sadeghian; Seyed Mehran Heidari
Abstract
Miandasht copper deposit is located in 110 km east of Shahrood, 24km north west of Abbasabad, and in the Cenozoic volcanic belt of north of Central Iran zone. The major rock units of the study area have Eocene age and include submarine flows (andesite, basalt, and trachyandesit), pyroclastic (tuff breccia ...
Read More
Miandasht copper deposit is located in 110 km east of Shahrood, 24km north west of Abbasabad, and in the Cenozoic volcanic belt of north of Central Iran zone. The major rock units of the study area have Eocene age and include submarine flows (andesite, basalt, and trachyandesit), pyroclastic (tuff breccia and agglomerate) and sedimentary complex (Nomullitic limestone, tuffacous limestone, shale, sandstone and conglomerate). Mineralization in the Miandasht copper deposit occurred as parallel to layering of the host rocks (tuff breccia and agglomerate), and also along with cross- cutting faults of the host rocks in form of stratabound and epigenetic ores. The main ore textures include vein- veinlets, open space filling, disseminated and replacement. The Ores contain primary pyrite, chalcopyrite, chalcocite, bornit, and secondary covellite, chalcocite, malachite, hematite and limonite. The most important wall rock alterations accompanied with mineralization are carbonatic- silicic, sericitic, argillic, and chloritic, and that the amound of carbonatization and silicification increases with closing to mineralization zones. According to geochemical studies, tectonic setting of the deposit was extensional environment formed in a continental margin volcanic arc. Based on essential characteristics of the copper mineralization such as tectonic setting, host rocks, mineralogy, and type of alterations, the Miandasht copper deposit shows many similarities with Manto- type deposits, dominantly formed during orogeny, folding and faulting of the host sequence. It should be mentiond that some charachteristic features of the Miandasht copper deposit including development of argillic alteration, and lack of extensive zeolitic alteration, distinguishes it from other copper deposits in the region including Abbasabad deposit.
Economic Geology
Hossein Ali Tajeddin; Ebrahim Rastad; Abdolmajid Yaghoubpour; Mohammad Mohajjel
Abstract
The Mirgenaghshineh gold deposit is located 43 km northwest of Saqqez in the northwestern part of the Sanandaj–Sirjan zone. The rocks in the deposit area predominantly consist of Precambrian volcanosedimentary sequences of schist, metasandstone, slate and metaandesite which are intruded by granitoid ...
Read More
The Mirgenaghshineh gold deposit is located 43 km northwest of Saqqez in the northwestern part of the Sanandaj–Sirjan zone. The rocks in the deposit area predominantly consist of Precambrian volcanosedimentary sequences of schist, metasandstone, slate and metaandesite which are intruded by granitoid bodies. The Gold mineralization in the Mirgenaghshineh deposit is hosted mostly in Northwest-Southeast shear zone. The high grade gold ores occure in highly deformed mylonitic and ultramylonitic rocks that are associated with quartz, sericite-muscovite and sulfide alteration minerals. Ore mineral assemblages of the deposit are simple and consist of pyrite, arsenopyrite, sphalerite, chalcopyrite, galena and electrum. The electrum grains range in size from less than 5 µm to 140 µm and occur in quartz and also in the form of inclusion and veinlet in pyrites. According of geochemical data, gold-bearing ores carry up to 64.3 ppm Au, 9.9 ppm Ag, 2096 ppm As, 506 ppm Pb, 354 ppm Zn, and 244 ppm Cu. Fluid inclusion studies on gold-bearing quartz indicate homogenization temperatures between 158 and 215°C and salinity between 3.3 to 14.5 wt% NaCl eq. for the ore fluid. The study indicates that main characteristics of the geology and mineralization of the Mirgenaghshineh are similar to those of the epizonal orogenic gold deposits.
Economic Geology
Nima Rahimi; Shojaeddin Niroomand; Mohammad Lotfi; Mojtaba Rahimi Shahid
Abstract
The Janja Cu-Mo porphyry deposit is located at 70 km south of the Nehbandan, Sistan suture zone, Eastern Iran. The porphyry mineralization in the Janja deposit is temporally and spatially associated with the diorite to quartz diorite and granodiorite granular to porphyry stocks that intruded in the Cretaceous ...
Read More
The Janja Cu-Mo porphyry deposit is located at 70 km south of the Nehbandan, Sistan suture zone, Eastern Iran. The porphyry mineralization in the Janja deposit is temporally and spatially associated with the diorite to quartz diorite and granodiorite granular to porphyry stocks that intruded in the Cretaceous flysch units. The Janja intrusions are represented by a Calc-alkaline and metaluminous geochemical affinity, and belong to the I-type granitoid series and subduction-related magmas in composition. Hydrothermal alterations in the area have been completely influenced by the Janja intrusion and as a result of the activity of these hydrothermal fluids, various types of potassic, propylitic, argillic and rarely phyllic alteration zones have been formed. In this deposit, three mineralization styles have been recognized including disseminated, vein-veinlet and stockwork which mineralization is mainly associated with potassic alteration. Mineralization zones in porphyry systems, including the supergene, enriched and hypogene zone, have been identified in the Janja deposit, which are the result of changes in the water table, weathering and erosion effects. The main sulfide minerals consist of chalcopyrite, pyrite, covellite, chalcocite, molybdenite, bornite, and oxide minerals including magnetite, hematite, goethite and hydro carbonate minerals including malachite and azurite. Fluid inclusion studies showed a homogenization temperature range from 301 to 540 ˚C and a mean salinity of 19 wt%NaCl for two-phase inclusions and a homogenization temperature range between 254 and >550 ˚C and mean salinities of 54 wt % NaCl for multiphase fluid inclusions. The results of these studies show that mixing processes have taken place in the Janja deposit and have caused the deposition of Cu-Mo-(Au) mineralization. Eventually, according to the various characteristics of the Janja deposit, including tectonic environment, host rock, mineralogy, ore-forming fluid, metal ore assemblage, mineralization and alteration patterns, and comparison of these characteristics with other porphyry deposits, it can be concluded that mineralization in Janja deposit is comparable with continental margin-type porphyry Cu-Mo-(Au) deposits.
Economic Geology
Shahram Mobaser; Taher Farhadinejad; Abbas Asgari; Mohammad Ali Ali Abadi; Shirin Fatahi
Abstract
The Barzavand copper deposit with Oligocene age located in 30 Km northeast of Zefreh along a tension fault with W-E trend and developed within basaltic lava with stratabound form. Alterations mainly include: pyritization, propylitization, zeolitization, silicification, saussuritization and uralitization ...
Read More
The Barzavand copper deposit with Oligocene age located in 30 Km northeast of Zefreh along a tension fault with W-E trend and developed within basaltic lava with stratabound form. Alterations mainly include: pyritization, propylitization, zeolitization, silicification, saussuritization and uralitization of basaltic lava. Furthermore geochemical studies in Barzavand show enrichment of SiO2, Al2O3, K2O, Na2O, P2O5, TiO2, ∑REE, Ag, As, Ba, Be, Bi, Cd, Cs, Cu, Li, Mo, Nb, Pb, Rb, Sb, Se, Sn, Sr, Ta, Tl, Te, Th, U, W, Y, Zn and Zr, enrichment- depletion of CaO, Fe2O3, MnO, Hf, Sc and V and depletion of S, Ni, Cr, MgO and Co during alteration. The positive correlation between (La/Lu)N, (La/Yb)N, (La/Sm)N and (La/Y)N and CaO (r= 0.70 to 0.96) indicate propylitization of host rock basalt and increase in pH of fluid responsible for mineralization that play important role in differentiation of lanthanides in study area. Ore minerals include chalcopyrite, bornite, covellite, azurite, malachite, hematite, goethite and pyrite. Copper is transported by means of chloride complexes into oxidized brines water related to late diagenesis stage and precipitated by substitution within pyrites formed during the volcanism process. It seems that the Barzavand copper deposit has submarine volcanism, early and late diagenesis, burial metamorphism and weathering stages during its evolution. According to alteration properties, mineralogy and the whole rock geochemistry, the Barzavand copper deposit is most similar to Manto type copper deposits.
Economic Geology
Monireh Sakhdari; Mehrdad Behzadi; Mohammad Yazdi; Nematollah Rashidnejad-Omran; Morteza Sadeghi Naeini
Abstract
The Godar Sorkh area is located in the central part of the Sanandaj-Sirjan zone, 20 km southwest of the Muteh region. Gold mineralization at Godar Sorkh occurs in quartz-sulfide veins that hosted in metasedimentary rocks. Veins of mineralization typically formed along normal faults. Rock sequences ...
Read More
The Godar Sorkh area is located in the central part of the Sanandaj-Sirjan zone, 20 km southwest of the Muteh region. Gold mineralization at Godar Sorkh occurs in quartz-sulfide veins that hosted in metasedimentary rocks. Veins of mineralization typically formed along normal faults. Rock sequences are affected by several deformation phase, gold mineralization occurs in ductile to ductile-brittle shear zones and had been under poly-phase metamorphism. The main alterations are Sulfidation, carbonization, silicification, chloritization, and sericitization. Ore-mineral assemblages include pyrite and chalcopyrite, arsenopyrite, sphalerite, galena, and Fe-oxide. Mean homogenization temperature in gold-bearing quartz range between 275oC and 300oC. Fluid inclusions in quartz veins are dominated by CO2-H2O-NaCl fluid. Salinity ranges from 9 to 17 wt. % NaCl equivalent. Corresponding to a depth of <2 km, Godar Sorkh deposit is formed in epizonal environment. Measured δ18O values for the gold-bearing quartz range between 12.7 to 14.3 permil, estimated δ18Ofluid values range from +6.4 to +7.3 permil, δ34S values range from –16 to +5 permil, and estimated δ34Sfluid values range from +4.2 to -17.3 permil. Fluid inclusion and stable isotope studies on ore-bearing quartz-sulfide veins indicating the major role of metamorphic fluids. Gold derived from metasedimentary rocks. Gold mineralization in the Godar sorkh deposit classified as an orogenic gold deposit.
Economic Geology
Kiamars Hosseini; Majid Shahpasandzadeh; Roghayeh zabihi khargh
Abstract
The Sangan Mining District (SMD) in the north of the Cenozoic magmatic belt of eastern Iran is constituted of predominantly acidic to intermediate volcanic and pyroclastic rocks, intruded by the Eocene granitoids. In the Baghak Fe skarn deposit, these granitoids are composed of pre-mineralization ...
Read More
The Sangan Mining District (SMD) in the north of the Cenozoic magmatic belt of eastern Iran is constituted of predominantly acidic to intermediate volcanic and pyroclastic rocks, intruded by the Eocene granitoids. In the Baghak Fe skarn deposit, these granitoids are composed of pre-mineralization biotite quartz monzonite, biotite syenite to biotite syenogranite, alkali feldspar quartz syenite to alkali feldspar granite and syn-mineralization quartz alkali syenite and quartz syenite. These I type granitoids have a magnesian metaluminous, calcalkaline, high K alkaline to shoshonitic nature. The granitoids show enrichment of LREE/HREE and LILE/HFSE with negative anomalies of Eu,Sr,Ta,Th and Ti, posetive anomalies of U, K, Ba, and Rb together with high La values and Zr/Nb, Nb/Th, Nb/U, and Nb/La ratios which suggest not only their slab-derived mantle source, but also crustal mixing in evolution of the magma. The Sm/Yb versus La/Sm, Sm/Yb versus Sm and Dy/Yb versus La/Yb show derivation of the primary melt from low partial melting (2-5 %) of a garnet-spinel lherzolite at depth of ~66-68 kilometers of the upper mantle, affected by continental crust melts. According to this research, the tectono-magmatic setting of the granitoids is suggested syn- to post-orogenic magmatic arc.
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 ...
Read More
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
Kourosh Shabani; Nima Nezafati; Morteza Momenzadeh; Mohammad Hashem Emami; Seyed Jamal Shaykhzakaryaii
Abstract
The Tareek Darreh gold Gold & Copper deposit is located 40km north of Torbat- e Jam in the Khorasan-Razavi province,NE-Iran. The study area is mainly comprised of slightly metamorphosed, sedimentary rocks of Jurassic age including alternation of shale, siltstone, and sandstone. These rocks have been ...
Read More
The Tareek Darreh gold Gold & Copper deposit is located 40km north of Torbat- e Jam in the Khorasan-Razavi province,NE-Iran. The study area is mainly comprised of slightly metamorphosed, sedimentary rocks of Jurassic age including alternation of shale, siltstone, and sandstone. These rocks have been intruded by plutonic rocks such as gabbronorite, diorite, quartz-diorite, and rhyodacite. The ore bodies are exposed by trenching and pitting. The alteration minerals quartz, chlorite, albite, and sericite which are observed mostly on the top or margin of the stocks. Alteration is more intensive at the contacts of the stocks where vein type mineralization has occurred. The veins are mainly composed of silica type and calcite type, arsenopyrite, chalcopyrite, and pyrite main ore minerals. Probably more than 2-stages telescopic mineralization occurred in these zones and the conditions of temperature and pressure, as seen below. Appears to be a continuation of tectonic activity in the same place as intrusive and a little later the main cause of this phenomenon. According to our studies, The Tareek Darreh gold deposit is considered to be similar to the "intrusion-related gold "type.
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. ...
Read More
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
Ali reza zarasvandi; Mohammad Ali Ali Abadi; Mohsen Rezaei; Houshang Pourkaseb
Abstract
The Mohammadabad deposit is located in vicinity of Delijan in central province and in terms of structural zones of Iran,in the Uremia dokhtar zone. Stratabound Fe-Ce mineralization in brecciated, vein, massive, layered and laminar forms, consists ore minerals such as hematite, pyrite, chalcopyrite and ...
Read More
The Mohammadabad deposit is located in vicinity of Delijan in central province and in terms of structural zones of Iran,in the Uremia dokhtar zone. Stratabound Fe-Ce mineralization in brecciated, vein, massive, layered and laminar forms, consists ore minerals such as hematite, pyrite, chalcopyrite and magnetite ,is seen in lower Eocene volcano sedimentary unites. Amounts , ratios and diagrams of trace elements and rare earth elements show hydrothermal mineralization with the predominance of magmatic fluids. The values of δ34SCDT of sulfide minerals (-2.76 to1.51 ‰) and suggest the magmatic source for sulfur or mineralizing fluid with magmatic sulfur. The values of δ13C (mean 3.61 ‰), δ18O(mean12.946‰) related diagrams show a magmatic source for carbon, hydrothermal genesis for calcite and a mineralizing fluid dominantly magmatic source. above evidences,وthe location of the region in tensile tectonic regime in western edge position of uremia dokhtar magmatic arc during the Eocene and presence of magmatic mass in the depths of the region with high potential for iron and copper mineralization , sulfur supply ,also has played role of a heat engine to circulating and transfer of mineralizing fluids to the sea bed. Offers exhalative-hydrothermal processes model for deposit genesis in Eocene volcano sedimentary units
Economic Geology
Almasi Alireza; Ghasem Nabatian; Amir Mahdavi; Qiuli Li
Abstract
The Maher abad and Khopik porphyry Cu deposits occurred in the Upper Eocene (39-37 Ma) in Lut block. All of them associated with intermediate (mostly monzonite) rocks. Porphyry deposits are closely associated with oxidized magmas. Oxygen fugacity (fO2) is a key factor that controls the formation of porphyry ...
Read More
The Maher abad and Khopik porphyry Cu deposits occurred in the Upper Eocene (39-37 Ma) in Lut block. All of them associated with intermediate (mostly monzonite) rocks. Porphyry deposits are closely associated with oxidized magmas. Oxygen fugacity (fO2) is a key factor that controls the formation of porphyry Cu deposits. The composition of the major and trace elements of zircon grains related to several ore-bearing monzonite were measured in Maher abad and Khopik porphyry copper indices. Zircon grains show moderate to low Ce4+/Ce3+ with a range of 19 to 610 and an average of 155. The average of oxygen fugacity (logfO2) values of Meher abad and Khopik ore-bearing magmas, range ∆FMQ -3.2 to MFMQ -1.3 with mean ∆FMQ -2.2, indicate formation under moderate oxidation conditions (between Ni-NiO (NNO) and Faylite magnetite-quartz (FMQ) buffers, but magnetite-hematite (HM) buffer, which ), which is not ideal for the formation of porphyry deposits. This is supported by whole-rock and Sr-isotopic data, and absence of high oxidation minerals such as hematite, and the poor adakitic charactristic of rocks in both deposits, which are due to factors involved in magma origin such as rock type and partial melting rate (possibly peridotite with low participation of slab).
Economic Geology
Negar Kaboudmehri; Hossein Kouhestani; Mir Ali asghar Mokhtari; Afshin Zohdi
Abstract
The Toryan occurrence is located in the Central Iran zone, 120 km northwest of Zanjan. Pb–Zn mineralization at Toryan occurred as laminated and lens-shaped parallel to lamination of grey sandstone units of the Upper Red Formation. Mineralization often formed around and within the fragments of the ...
Read More
The Toryan occurrence is located in the Central Iran zone, 120 km northwest of Zanjan. Pb–Zn mineralization at Toryan occurred as laminated and lens-shaped parallel to lamination of grey sandstone units of the Upper Red Formation. Mineralization often formed around and within the fragments of the plant fossils, and shows disseminated, replacement, solution seems, intergranoular cement, framboidal, and vein-veinlet textures. At Toryan, ore horizon has 1 m thickness and approximately 350 m length and contains three zones include the red oxidized zone, the bleached zone and the mineralized reduced zone. Galena, sphalerite, pyrite and arsenopyrite are the main ore minerals at Toryan occurrence. Cerussite and goethite are formed during supergene and wethering processes. Comparison of trace elements and REE patterns of barren red and grey host sandstones and mineralized samples indicate that mineralized samples show lower concentrations of trace elements and REE. Based on tectonic setting, sedimentary environment, host rock, presence of plant fossils, geometry, ore texture and mineralogy and alteration, Toryan occurrence can be classified as sediment-hosted Cu deposits of Redbed type, and is comparable with another Redbed type of Cu and Pb–Zn deposits in the Avaj-Zanjan-Tabriz-Khoy belt.
