Sedimentology
Hoda bavi; Reza Moussavi-Haramia; Mohamad Hosein Mahmudy Gharaie; Hamed Zand-Moghadam; Asadollah Mahboubi; Mohammad Reza Tohidi
Abstract
The geochemical separation pattern and environmental behavior of ΣREE have been investigated in five different sedimentary systems related to Dar-e-Allo copper mine. For this purpose, the total concentration and sequential patterns of ΣREE elements were determined using multi-acid digestion ...
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The geochemical separation pattern and environmental behavior of ΣREE have been investigated in five different sedimentary systems related to Dar-e-Allo copper mine. For this purpose, the total concentration and sequential patterns of ΣREE elements were determined using multi-acid digestion and mBCR selective extraction method. The normalization patterns of ΣREE are drawn based on the NASC and UCC. concentration changes in the five sedimentary systems are very similar and the concentration of LREEs is higher than that HREEs, Opposite of the changes in the concentration of ΣREEs, more enrichment is seen in HREEs compared to LREEs. The geochemical separation patterns of ΣREEs in natural sediment and samples containing iron and manganese oxides is mainly dominated by the residual fraction. considering the different conditions of formation and stability in the samples taken from the waterways leading to the mine, evaporite deposits and sediments washed from the rock dump, the separation pattern of ΣREEs is controlled mainly with two parts soluble in Acid and reducible fraction. The trend of mobility and bioavailability from LREEs to HREEs increases with an upward slope. These results show that speciation, geochemical segregation pattern and environmental behavior for ΣREE lead to misinterpretation without considering key environmental factors.
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, ...
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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
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 ...
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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.
Petrology
Hamid Karimzadeh; Mohammad Rahgoshay; Iman Monsef
Abstract
The petrographical examination of peridotites of the Nehbandan ophiolitic complex revealed that the peridotites of Kalateh Shahpouri, Qadamgah, Lah-Kouh, Cheshmeh anjir, Bandan, and Zolfaghari were of harzburgite type and Sefid-Kouh and Nasfandeh-Kouh were of lherzolite type. Generally, the types of ...
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The petrographical examination of peridotites of the Nehbandan ophiolitic complex revealed that the peridotites of Kalateh Shahpouri, Qadamgah, Lah-Kouh, Cheshmeh anjir, Bandan, and Zolfaghari were of harzburgite type and Sefid-Kouh and Nasfandeh-Kouh were of lherzolite type. Generally, the types of clinopyroxenes in the peridotites of this complex were diopside. The geochemical investigation of clinopyroxenes in Mg# vs. Al2O3, Cr2O3, and TiO2 graphs and Ti vs. Nd, Zr, and Sr graphs shows that the peridotites of Nasfandeh-Kouh, Bandan, Zolfaghari, and Sefid-Kouh with a low degree of partial melting belong to the Abyssal tectonic setting and back-arc basin.on the other side, the harzburgites of Kalateh Shahpouri and Cheshmeh anjir were formed in the Supra-subduction zone tectonic setting and fore-arc basin and have a high degree of partial melting. The study of incompatible elements, LILE and HFSE in spider diagrams normalized to the primary mantle and as well as the study of REEs in spider diagrams normalized to the chondrite for clinopyroxenes confirm this issue. Therefore, Nasfandeh-Kouh and Sefid-Kouh lherzolites as well as Qadamgah, Lah-Kouh, Bandan, and Zolfaghari harzburgites with a low degree of depletion were more consistent with the Mid-oceanic ridgestectonic setting, and the harzburgites of Kalateh Shahpouri and Cheshmeh anjir were close to the Supra-subduction zone tectonic setting with a high degree of depletion.
Petrology
Ali Lotfi Bakhsh
Abstract
In the north of Ardabil (from Namin to Lahroud) there are widespread sequences of Eocene and Quaternary mafic to intermediate and felsic magmatic activities with different compositions. The composition of these rocks varies from basaltic lavas as well as dacitic and rhyolitic domes in Namin to basalt ...
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In the north of Ardabil (from Namin to Lahroud) there are widespread sequences of Eocene and Quaternary mafic to intermediate and felsic magmatic activities with different compositions. The composition of these rocks varies from basaltic lavas as well as dacitic and rhyolitic domes in Namin to basalt and basaltic andesite in Lahroud area. The chemical composition of olivine from olivine basaltic lavas indicates a forsterite composition changing from 67.8 to 92.7. Clinopyroxenes show diopside composition whereas plagioclase has labradorite to bytownite composition. Garnet xenocrysts in the rhyolitic domes have an almandine composition. These rocks are characterized by the enrichment in LREEs compared to the HREEs. Mafic-intermediate rocks show shoshonitic to high-K calc-alkaline composition whereas dacitic and rhyolitic domes show adakitic signature. Geochemical and isotopic characteristics of basaltic-andesitic rocks indicate their genesis are related to the partial melting of a metasomatized mantle wedge, re-fertilized by sediments and fluids from the subducting slab in the Eocene subduction zone of Iran. The geochemical and isotopic signatures of dacitic-rhyolitic domes indicate their origin from partial melting of the lower parts of the thickened continental crust of Iran.
Petrology
Jalil Ghalamghash; Meysam Akbari; Reza Jamal
Abstract
The Taftan volcano hosts an extensive volcanic activity during Late Miocene to Quaternary where took place over Makran-Chagai subduction zone. Taftan rocks are mainly basaltic andesite, andesite, trachyandesite, and dacite that occur as lavas and pyroclastic rocks. They are characterized by basic-intermediate ...
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The Taftan volcano hosts an extensive volcanic activity during Late Miocene to Quaternary where took place over Makran-Chagai subduction zone. Taftan rocks are mainly basaltic andesite, andesite, trachyandesite, and dacite that occur as lavas and pyroclastic rocks. They are characterized by basic-intermediate inclusions enclosed by acidic groundmass, and disequilibrium textures in plagioclase phenocrysts including sieve texture, zoning, and dissolution margin, which may reflect magma mixing. These rocks record high-K calc-alkaline to calc-alkaline affinity with enrichment in LREE and LILE relative to HREE and HFSE, respectively. These features, coupled with the clear depletion in HFSE (such as Nb, Ta, and Ti) are consistent with typical subduction-related volcanic arcs. Taftan primary melts might have been produced by ~15% partial melting of spinel lherzolite mantle. The normalized multi-element patterns which mimic the upper continental crust values, and enrichment in Pb, Th, U, and Rb agree well with magma evolution by assimilation and fractional crystallization (AFC). The available isotopic geochronology dataset reveal that the youngest volcanoes of the Makran-Chagai magmatic arc are Bazman and Kuh-e-Sultan volcanoes. A geochemical comparison of these volcanoes highlights that magmatism in the Taftan where the crust is thick, underwent a higher degree of crustal assimilation en route to the surface.
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 ...
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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.
Petrology
Ziba Khodaean Chegeni; Nematollah Rashidnejad Omran; Ali Akbar Baharifar; Reza Nozaem; Carmela Vaccaro; José Francisco Santos
Abstract
Takhte-Soleyman ortho-amphibolites as a part of Takab metamorphic complex are located in Northeast Takab. These rocks consist of amphibolite, Garnet-amphibolite, Kyanite-Garnet-amphibolite, Hornblendite and Epidote-amphibolite. Petrography and whole- rock geochemistry show that basalt, andesite and/or ...
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Takhte-Soleyman ortho-amphibolites as a part of Takab metamorphic complex are located in Northeast Takab. These rocks consist of amphibolite, Garnet-amphibolite, Kyanite-Garnet-amphibolite, Hornblendite and Epidote-amphibolite. Petrography and whole- rock geochemistry show that basalt, andesite and/or their intrusive equivalents with calc- alkaline to tholeiitic affinity and even a peridotite could be their protoliths. Trace element and Sr-Nd ratios imply that these rocks were from mantle melt sources. In chondrite normalized plots, these amphibolites can be classified into at least two groups. The first group is characterized by LREE depletion relative to HREEs and some with flat patterns. The second has an enrichment of LREEs relative to HREEs. These two different patterns and some other geochemical characters suggest MORB or MORB-like and arc affinities of the parental magmas. This can be related to the time progressive evolution of magmatism either from MORB or Back-arcto Arc or from Arc to Back-arc setting.
Sedimentology
Mohammad Shalalvand; Mohammad Adabi; Afshin Zohdi
Abstract
In this study, the Late Paleocene Taleh Zang Formation in the southwest of Kermanshah hasbeeninvestigatedfor elemental geochemistry and effective diagenetic processes during burial. The thickness of the studied section is 282 meters that mainly composed of shallow marine limestones with interbedded of ...
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In this study, the Late Paleocene Taleh Zang Formation in the southwest of Kermanshah hasbeeninvestigatedfor elemental geochemistry and effective diagenetic processes during burial. The thickness of the studied section is 282 meters that mainly composed of shallow marine limestones with interbedded of marl and dolomite. The main diagenetic processes affecting the TalehZangFormation include micritization, various types of porosity, cementation, dolomitization and compaction. Due to the texture and the abundance of unstable skeletal particles (green algae and bivalve), porosity and cementation aremorecommon among the identified processes. Microscopic and geochemical studies have shown that these processes have taken place in eogenesis and early mesogenesis stages in marine, meteoric and shallow burial environments. Evidences indicate that the carbonates of the TalehZangFormation didnot tolerate deep burial after the deposition during diagenesis. Fluids that affected the lower parts of the formation during burial were mainly marine. Moreover, tothetop ofthe sequence in addition to seawater less meteoric fluids have affected the marine carbonates of the Taleh Zang Formation during diagenesis. The high amounts of Sr/Mn (mean27/51) and Sr/Ca (mean 1/61) and also low Mn (mean 27ppm) and Fe (mean 78ppm) values indicate close digenetic system with low water/rock interaction for the carbonate samples of the TalehZangFormation.
Sedimentology
Hadi Amin-Rasouli; Hossein Azizi; shahla mahmodyan
Abstract
The Upper Cretaceous succession (UCS) of the north Sanandaj-Sirjan zone consists of five units. The units are 2000 m thick, including shale, sandstone, limestone, intrafomational conglomerate with interbedded basaltic- andesitic lava. This succession is unconformably underlain by Lower Cretaceous and ...
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The Upper Cretaceous succession (UCS) of the north Sanandaj-Sirjan zone consists of five units. The units are 2000 m thick, including shale, sandstone, limestone, intrafomational conglomerate with interbedded basaltic- andesitic lava. This succession is unconformably underlain by Lower Cretaceous and overlain by Paleocene conglomerates. The geochemistry of the samples represents ratios of Al2O3/TiO2 (18-22), La/LuCN (5.43-24.4), La/Sc (0.51-2.53), Th/Sc (0.42-0.68), LREE/HREE (Nd/ErCN > 5), and negative anomalies of Eu/Eu* (0.26-0.89) and Nb/Nb* (0.14-0.82). These characteristics indicate that the samples are immature, first-order sediments, and were eroded from intermediate to acidic arcs in the subduction zone. The volcanic rocks were formed during the intracrustal melting of an altered oceanic slab at high pressures in the garnet-amphibolite facies. The geochemical compositions and vertical lithofacies stacking patterns of the UCS imply that the depositional environment has changed during sedimentation from a trench to trench slope and forearc basins arising from continent-ward migration of the magmatic arc. The activities of Late Cretaceous volcanism resulted in the upwelling of anoxic water, demise of planktonic, and formed pyrite in the deposits. Samples on the Th/Yb-Ta/Yb diagram fall in the ACM and WPVZ fields, indicating tectonic evolution from low-gradient subduction to extensional volcanic conditions.
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
Robabe masoomi; Yoseph Rahimsouri; Hemayat Jamali; Ali Abedini
Abstract
The action of alteration processes on the Eocene tuffs has led to the formation of a spread argillic alteration zone in the Kamar district (south of Ardebil, Tarom-Hashtjin Zone). The aim of this study is to determine the factors controlling argillic alteration, using mineralogical studies and chemical ...
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The action of alteration processes on the Eocene tuffs has led to the formation of a spread argillic alteration zone in the Kamar district (south of Ardebil, Tarom-Hashtjin Zone). The aim of this study is to determine the factors controlling argillic alteration, using mineralogical studies and chemical alteration indices. Quartz, kaolinite, muscovite (sericite), rutile, anatase, illite, diaspore, alunite, albite, clinochlore, jarosite, gypsum, pyrite, orthoclase and dolomite are the mineral assemblage of this alteration zone. The mineralization of sulfides includes pyrite (predominantly), chalcopyrite, borneite, chalcocite, galena, and sphalerite. The chemical index of alteration (CIA) values are between 51.55 to 74.3 %, and the mineralogical index of alteration (MI) values vary from 8.22 to 48.3%. The mafic index of alteration (MIA(O)) ranges from 55.88% to 87.48%, Depletion of a large number of elements, including some immobile elements (Zr, Y, V, Al and LREEs), the presence of minerals indicating acidic pH, such as jarosite and alunite, and high-temperature minerals such as rutile and anatase, the presence of the vuggy quartz in some altered regions, and concomitant enrichment of As, Sb and Mo, in the Kamar argillic zone, bear similarities to the hot fluid alterations of high-sulfidation epithermal deposits.
Economic Geology
Hossein Bagherpour; Mir Ali Asghar Mokhtari; Hossein Kouhestani; Ghasem Nabatian
Abstract
Qoyjeh Yeylaq volcanic rocks is located approximately in the 120 km southwest of Zanjan, within the Central Iranian zone. The rock units in this area belong to the Cenozoic which consist of mainly Oligo-Miocene volcanic (Basaltic- andesitic lavas) and sedimentary rocks. Based on geochemical classification, ...
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Qoyjeh Yeylaq volcanic rocks is located approximately in the 120 km southwest of Zanjan, within the Central Iranian zone. The rock units in this area belong to the Cenozoic which consist of mainly Oligo-Miocene volcanic (Basaltic- andesitic lavas) and sedimentary rocks. Based on geochemical classification, the mentioned volcanic rocks are basalt, basaltic andesite and andesite in composition, and have calc- alkaline to high-K calc-alkaline affinity. In the primitive mantle normalized spider diagrams, all of the volcanic rocks show similar patterns with enrichment in LILE (Ba, Th, K, Pb) and negative anomalies of HFSE (Nb, Ti). These rocks show LREE enrichment relative to HREE and high ratio of LREE/HREE. Based on tectonomagmatic discrimination diagrams these volcanic rocks were formed in a continental arc setting. Based on geochemical data, it seems that volcanic rocks of the Qoyjeh Yeylaq area were formed from 5-20 % partial melting of a garnet- spinel lherzolite enriched mantle by subduction of Neo-Tethys under the central Iran, within the Orumieh- Dokhtar magmatic arc.
Petrology
Ayoub Veisinia; Mohammad Ebrahimi; Bahman Rahibzadeh; rasoul Esmaeili
Abstract
Kamyaran ophiolitic complex located in the northeast Zagros orogeny along the crush zone between Arabian-Iranian plates. This complex outcropped between the Harsin ophiolites in southeast and Sarwabad ophiolite in northwest. Field observation reveal the fact that the Garmab Ophiolite in the northeast ...
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Kamyaran ophiolitic complex located in the northeast Zagros orogeny along the crush zone between Arabian-Iranian plates. This complex outcropped between the Harsin ophiolites in southeast and Sarwabad ophiolite in northwest. Field observation reveal the fact that the Garmab Ophiolite in the northeast of Kamyaran is a tectonic mélange including peridotites and gabbros cut by microgabbroic dikes. Olivine, clinopyroxene and orthopyroxene with chromian spinel made the peridotites minerals with mesh and porphyroclastic fabrics and Gabbros include plagioclase, clinopyroxene and minor amphibole with intergranular, pegmatoidic and interstitial texture. According to the geochemical results, gabbros have tholeiitic to calk-alkaline nature and show the MORB to island arc characteristics. According to the geochemical and geotectonic results, Garmab peridotites plotted to the abyssal peridotites area that represent from the residual mantle spinel lherzolite after extraction of 15–20% partial melting. The break-off of Neo-Tethyan slab and subduction of this slab branch beneath the oceanic lithosphere during cretaceous led to cessation of the Neo-Tethyan subduction beneath the Sanandaj-Sirjan block, and forming arc-back arc basin (second step of subduction) and related rocks in the Kamyaran ophiolite. Presence of tholeiitic to calc-alkaline magmatism is in response to the slab retreat in the Eurasian continental margin.
Petrology
hojjat hajhassani; Jalil Ghalamghash; Mansour Vousoughi Abedini; Rahim Dabiri; Hamideh Rashid
Abstract
The leucocratic granite emplaced as small masses and dykes in the Alvand batholith. The leucocratic granite consists of tourmaline alkali granite, biotite alkali granite, arfvedsonite alkali granite, rutil alkali granite, and biotite- muscovite granites with alkaline and peraluminous affinities. They ...
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The leucocratic granite emplaced as small masses and dykes in the Alvand batholith. The leucocratic granite consists of tourmaline alkali granite, biotite alkali granite, arfvedsonite alkali granite, rutil alkali granite, and biotite- muscovite granites with alkaline and peraluminous affinities. They show enrichments of LREEs relative to HREEs and LILE relative to HFSE with negative anomalies in Nb, Ta and Ti, in normalized trace element diagrams. The leucocratic granite of the Alvand batholith resemble A-type and can be further classified in two of A and A' types granite. The trace elements content of A-type is much higher than A'-type granite. Based on geochemical data, it seems that A- and A'-type granites were generated from partial melting of mantle source. As mantle magma ascends, fractionate and empalce into the crust, A-type leucocratic are formed with minimal contamination and A'-type leucocratic with significant contaminant with continent crust are formed. Field and geochronology data suggest that the leucocratic granite were generated in the late Jurassic, which is contemporaneous with the subduction of the Neo-Tethys oceanic crust beneath the central Iran. It seems that the leucocratic granites were emplaced during a local extensional phase as dykes and small bodies in the Alvand batholith.
Economic Geology
masoumeh Norouzi; Ali Abedini; Ali Asghar Calagari; Fatemeh Kangarani Farahani
Abstract
The kaolin occurrence in the Abolhasani-Zereshkouh area (south of Shahroud, northeast of Iran) is a product of alteration of Eocene andesitic rocks. With attention to mineralogical studies, kaolinite, quartz, chlorite, montmorillonite, illite, rutile, calcite, orthoclase, albite, vermiculite, palygorskite, ...
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The kaolin occurrence in the Abolhasani-Zereshkouh area (south of Shahroud, northeast of Iran) is a product of alteration of Eocene andesitic rocks. With attention to mineralogical studies, kaolinite, quartz, chlorite, montmorillonite, illite, rutile, calcite, orthoclase, albite, vermiculite, palygorskite, jarosite, and hematite are the mineral assemblege of this alteration occurrence. Calculations of mass balance of elements with assuming Zr as monitor immobile element show that elements such as Si, Fe, Mg, Na, K, Ti, Cr, Ba, Be, Co, Cs, Rb, Sn, U, V, W, Ni and REE were partially depleted and elements such as Hf, Zn and Cd enriched during the kaolinitization processes of andesitic rocks. Other elements including Al, Ca, P, Mn, Ga, Nb, Sr, Ta, Th, Y, Cu, Pb and Tl were undergone both leaching and fixation processes. The mass decrease of Si, Fe, K, Rb, Cs and Ba reveals destruction of plagioclase and hornblende by highly acidic hydrothermal fluids. The presence of two abnormal decreasing and increasing trends for the elements Al, Ga, P, Nb, Ta, and Y can be attributed to the low pH of the altering fluids, the high water-to-rock ratio and the abundance of complexing legands.
Economic Geology
afshin akbarpour; Masoud Moslehi
Abstract
Yapal iron ore body is located in northwest of Sanandaj-Sirjan zone. A complex of Paleozoic metamorphed rocks including green schist, mica schist, chlorite schist with green schist facies degree, plus skarn and marble outcrop in this area.. Iron mineralization generally occurs as magnetite with the shapes ...
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Yapal iron ore body is located in northwest of Sanandaj-Sirjan zone. A complex of Paleozoic metamorphed rocks including green schist, mica schist, chlorite schist with green schist facies degree, plus skarn and marble outcrop in this area.. Iron mineralization generally occurs as magnetite with the shapes of lentoid, veins, veinlets and dots in garnet schist and greenschist and near marble outcrop in area. Ore textures are observed as dispersed, stock, replacement and network like. The iron oxide grade varies between 30 to 60 percent. Iron element negatively correlates with sulfur and positively correlates with titanium, magnesium, manganese and the other main oxides. Based on the relation between cobalt and nickel, this ore body is located within hydrothermal-originated category. Some samples are located in the hydrothermal-volcanogenic boundary. Based on distribution patterns of rare earth elements, Yapal iron ore has more similarities with skarn type mineralizations. Geochemical evidences of magnetite and the variations of cobalt, nickel, silica and aluminum suggest the skarn origin for Yapal iron ore. That means the iron has been mobilized by the hot fluids originated by intrusive stocks and precipitated in contact of metamorphic and marble units.
Petrology
Mahboobeh Jamshidibadr; Narges Sadat Faramarzi
Abstract
Hormuz Island, a salt diapir in southern Iran, mostly composed from evaporite-carbonate sediments of Neoproterozoic. So far, no significant studies have been done belong to the petrography and geochemistry of the Hormuz evaporite-carbonate sediments. Moreover, Salt movements made it difficult to distinguish ...
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Hormuz Island, a salt diapir in southern Iran, mostly composed from evaporite-carbonate sediments of Neoproterozoic. So far, no significant studies have been done belong to the petrography and geochemistry of the Hormuz evaporite-carbonate sediments. Moreover, Salt movements made it difficult to distinguish rocks relationship only based on field observations. In the recent study, with the understanding of field evidences (e.g. the salt thickness, type and amounts of enclaves, as well as field relationship between evaporite unit and volcanic rocks), mineralogical studies (such as studying fluid inclusions within evaporite unit, studying enclaves from evaporite-carbonate unit as well as the mineralogy of dolomite, pyrite and rhyolitic tuffs) and doing geochemical analysis (e.g. Inductively coupled plasma- mass spectrometry and Scanning Electron Microscope), not only the evaporite-carbonate sediments, but also the reconstruction of the events occurring in the Hormuz sedimentary basin, have been investigated. The existence of evaporites with different thicknesses, enclaves and interlayers indicate that deposition of evaporites occurred in two separate stages. The island’s rhyolitic volcanism happened in the gap between sedimentation of lower and upper evaporite units. The volcanoclastic rocks are coexistence with deposition of upper evaporite unit. The deposition of both evaporite units occurred during the upper Ediacaran.
Sedimentology
Javad Anjerdi; Mahdi Jafarzadeh; Adel Najafzadeh; Rahim Mahari
Abstract
In this research, a combination of petrography, geochemistry and heavy minerals analysis methods are implemented for investigating the provenance of quartzarenitic and subarkosic sandstones of Ilanqareh Formation with Late Devonian age in Azerbaijan, south of Jolfa. Investigation of the quartz types ...
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In this research, a combination of petrography, geochemistry and heavy minerals analysis methods are implemented for investigating the provenance of quartzarenitic and subarkosic sandstones of Ilanqareh Formation with Late Devonian age in Azerbaijan, south of Jolfa. Investigation of the quartz types in the studied sandstones, geochemical characteristics of sandstones and shales of Ilanqareh Formation including Al2O3/TiO2 ratio and La/Sc against Co/Th ratios, illustrates that the dominant parent rocks of most of these deposits are granitic igneous ones. The presence of granitic parent rock along with the presence of euhedral zircon and tourmaline among the well-rounded indicate the erosion of uplifted blocks of Iranian basement in the rifted basin of Paleotethys as effective factor in providing sediments. However, geochemistry and heavy mineral assemblages confirm the recycling of sediments from older formations as another source of sediment. The petrography, geochemistry and heavy minerals also indicate the craton provenance and passive margin tectonic setting at the deposition time of the Ilanqareh sediments. According to the present study, one can consider a combination of uplifted source rock (Cadomian basement) and sedimentary recycling of older formations as main sources and Arabian craton as a subsidiary source in the supply of detritus sanstones of Ilanqareh Formation.
Economic Geology
Sanaz Ahmadi; Mohammad Ali Salehi; H Jamali
Abstract
The Hassan Abad Zn-Pb deposits is located in the northeast of Isfahan, Central Iran zone. The host rock of this mineralization is the dolomite of Middle Triassic Shotori Formation. Mineralization included galena, sphalerite, sulfosalts, pyrite and barite which associated with dolomitization. Based on ...
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The Hassan Abad Zn-Pb deposits is located in the northeast of Isfahan, Central Iran zone. The host rock of this mineralization is the dolomite of Middle Triassic Shotori Formation. Mineralization included galena, sphalerite, sulfosalts, pyrite and barite which associated with dolomitization. Based on petrographic studies six types of dolomites (in terms of shape and size of the crystals, the distribution of crystal size and shape of the border crystal) has been identified, that including very fine, medium, coarsely crystalline dolomite, Saddle dolomites and filling pore spaces and veins. The first and second type of dolomites were formed as synsedimentary or diagenetic dolomite with sabkha origin. The third type of dolomite in the late stages of diagenesis was formed in shallow burial conditions due to recrystallization of small crystalline dolomite. Coarse-grained and saddle dolomites have been created under the conditions of deep burial and as hydrothermal dolomites and are related to mineralization. Move over, the origin of magnesium for fine crystalline dolomites were seawater, and for coarse crystalline dolomites are probably the brine fluids of the compacted Sorkh Shale Formation and hydrothermal fluid.
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
Raziyeh Mahabady; Farajollah Fardoost
Abstract
Abgareh copper deposit located in 140 km southwest of shahrood and part of a volcanic-sedimentary Torud-Chah shirin belt that has facies in the northern edge Structural-sedimentary zones of Central Iran. Field and petrographical studies, deposit area, consist of andesite, basaltic andesite and basalt ...
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Abgareh copper deposit located in 140 km southwest of shahrood and part of a volcanic-sedimentary Torud-Chah shirin belt that has facies in the northern edge Structural-sedimentary zones of Central Iran. Field and petrographical studies, deposit area, consist of andesite, basaltic andesite and basalt and contains less includes tuffit crystal that indicate middle–upper Eocene with with argillitic, sericitic, silicic, carbonatic, chloritic and iron oxides alterations. According to the field observations and mineralogical studies, the mineralization in the region was carried out in two stages: hypogene and supergene and weathering. Hypogen zone minerals are generally pyrite, chalcopyrite and bornite. Because of existence in oxidizing-supergene environment , nearly almost Cu-bearing minerals of the main stage of mineralization have been replaced by secondary Cu minerals such as chalcocite, covellite, malachite and chrysocolla. Fluid inclusion data shows in the temperature range from 145 to 217 °C and salinity between 3.73 and 9.84 Wt%NaCl and depths less than 390 m. The host rocks, ore mineralogy, ore structures and textures, and fluid inclusions characteristics and comparison with similar epithelial deposits indicate that the Abgareh vein system is formed in a low-sulfidation epitermal environment.
Economic Geology
Maryam Honarmand; Ghasem Nabatian; Mahtab Aflaki; Mohammad Ebrahimi
Abstract
Geology, geochronology and tectonic setting of the Moghanlou mylonite gneiss and granite bodies, west of Zanjan Abstract The Moghanlou mylonite gneiss and granite assemblage is located in the west of Zanjan forming a part of the magmatic-metamorphic association in the Takab area. The Moghanlou assemblage ...
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Geology, geochronology and tectonic setting of the Moghanlou mylonite gneiss and granite bodies, west of Zanjan Abstract The Moghanlou mylonite gneiss and granite assemblage is located in the west of Zanjan forming a part of the magmatic-metamorphic association in the Takab area. The Moghanlou assemblage comprises of leucogranite and biotite granite intrusions which have surrounded the gneiss body. The zircon U-Pb dating shows the ages of 563±6.5 Ma for the mylonite gneiss, 576±13 Ma for the biotite granite and 559±6 Ma for the leucogranite intrusions. Moreover, the samples from the Moghanlou assemblage display high-K calc-alkaline and slightly peraluminous affinities, except those from the leucogranite which are low potassium samples due to the sodic alteration and albitization of the K-feldspars. The trace element patterns suggest LILE and LREE enrichment and HFSE and HREE depletion as well negative anomaly of Nb, Ta and Ti. In general, the geochemical features of the Moghanlou intrusions are comparable with the melts formed from crustal partial melting in magmatic arc environment. The Moghanlou assemblage is analogues to other Late Neoproterozoic-Early Cambrian igneous and metamorphic associations in Iran and Turkey which are related to the igneous activity along the Cadomian magmatic arc, in north of Gondwana supercontinent.
Economic Geology
faraj fardoost; Akbar Abdollahi Hydarbaghi; Solmaz Baluchi
Abstract
The Robaei Iron deposit is located in 96km south of Damghan. Host rocks of deposit are Late Cretaceous limestones (part I) and Eocene volcano- sedimentary rocks including sandy tuff (part II.( The alterations include chloritization, epidotization, argillation, silicification, carbonatization and hematitization. ...
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The Robaei Iron deposit is located in 96km south of Damghan. Host rocks of deposit are Late Cretaceous limestones (part I) and Eocene volcano- sedimentary rocks including sandy tuff (part II.( The alterations include chloritization, epidotization, argillation, silicification, carbonatization and hematitization. Minerals forming can be divided into three groups; iron minerals (hematite, magnetite, pyrite, pyrrotite goethite and limonite), copper- minerals (chalcopyrite, chalcocite, covellite and malachite) and gangue minerals (calcite, dolomite, quartz, garnet, epidote and chlorite). The structure and textures of ore minerals are massive, vein- veinlet, open space filling and disseminated. In part I, the metals grade of Fet is about 60%, Cu 0.7 % and Au 2.7 ppm and in the part II, the Fet are variables between 5.88 to 82.91% (average 31.2%), Cu between 275 to 20761 ppm and Au 0.89 ppm. Fluid inclusion studies were carried out on quartz mineral from the part II that homogenization temperature is frequency variables between 200 to 249°C with salinity of 2-4% wt. %NaCl. Based on the results of this investigation, part I has similarities with calcic skarn of low temperature and part II showed more similarities with iron oxide- copper- gold (IOCG) deposits.
Petrology
Mahnoush Bahjati; A. Ahmadi; Habib Biabangard
Abstract
The volcanic rocks of Kuleh sangi-Malek siah kuh igneous complex consist of alkalibasalt, basalt, basaltic andesite, andesite, dacite and trachyte. In the SiO2 versus K2O diagram, the basaltic samples are plotted in the shoshonitic field and the subalkaline samples are plotted in the medium K calc alkaline ...
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The volcanic rocks of Kuleh sangi-Malek siah kuh igneous complex consist of alkalibasalt, basalt, basaltic andesite, andesite, dacite and trachyte. In the SiO2 versus K2O diagram, the basaltic samples are plotted in the shoshonitic field and the subalkaline samples are plotted in the medium K calc alkaline series field. The average La/Yb, Rb/Zr and Cs/Hf ratios in basalts are 7, 47 and 63 times those of N-MORB, respectively. Considerable enrichment of LILEs, LREEs and relative depletion of HREEs indicate that the magmas originated from a mantle source more enriched than that of OIB, where phlogopite and garnet are stable. Using non-modal batch melting model, the compositions of the mafic samples are mainly consistent with about 5% melting of a phlogopite-bearing and garnet-bearing lherzolite with a mixture of about 80% and 20%, respectively. AFC models using Pb versus Ce/Pb and Rb versus K/Rb, show that the fractionated samples have undergone simultaneous crustal assimilation and fractional crystallization. It seems that the assimilation and the fractionation had been taken place with the same rate. Depletion in Y and elevated ratio of Sr/Y of fractionated rocks in addition to Rb/Nb ratio more than 8, could be considered as evidence for crustal assimilation.
