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
Arefeh Heidarianmanesh; Seyed Mohsen Tabatabaimanesh; Narges Shirdashtzadeh
Abstract
Based on field observation and petrographic evidence, by progress in metamorphic degrees, a wide variety of metabasites have formed following the metamorphism at amphibolite facies (metamorphism M1) in the east of Jandaq. Thermobarometry of plagioclase- amphibole pairs indicate temperature ranges were ...
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Based on field observation and petrographic evidence, by progress in metamorphic degrees, a wide variety of metabasites have formed following the metamorphism at amphibolite facies (metamorphism M1) in the east of Jandaq. Thermobarometry of plagioclase- amphibole pairs indicate temperature ranges were 642-692ºC and 688-712 ºC for epidote amphibolites and garnet amphibolite, respectively, in a pressure range of 8 and 11 Kbar, correlating with transition from middle amphibolite to upper amphibolite facies. In addition to this metamorphic phase, petrographic signatures indicate further metamorphic phases concerning this region's geological phenomena. Based on brittle deformation in amphiboles, and epidote and quartz formation in their fractures, these rocks have undergone some degrees of retrograde metamorphism (<700 ºC; metamorphism M2) at greenschist to lower amphibolite facies. Rock foliation and mineral orientation, aggregate shape preferred orientation (ASPO) of titanite crystals along foliation, and syn-tectonic euhedral garnets indicate prograde metamorphism toward amphibolite-upper amphibolite facies (metamorphism M3). Finally, under greenschist facies condition, minerals such as chlorite and actinolite were formed in these rocks (metamorphism M4). The formation of chlorite and actinolite in the rims of the primary crystals shows that these rocks were finally affected by metamorphism at greenschist facies (M4 metamorphism).
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
Mahsa Jamshidnia; manijeh Asadpour; Masoumeh Ahangari
Abstract
Qushchi gneisses in the north of Urmia city are a part of magmatic-metamorphic complex in NW of Sanandaj-Sirjan zone. Gneiss, with eldsparses and schist, form Precambrian basement of the area. These rocks contain lipidogranoblastic, augen, porphyroblastic and myrmekite textures, and composed of quartz+ ...
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Qushchi gneisses in the north of Urmia city are a part of magmatic-metamorphic complex in NW of Sanandaj-Sirjan zone. Gneiss, with eldsparses and schist, form Precambrian basement of the area. These rocks contain lipidogranoblastic, augen, porphyroblastic and myrmekite textures, and composed of quartz+ alkaline eldspars (orthoclase and microcline perthites) + plagioclase+ biotite± pyroxene, muscovite± amphibole± epidote +zircon+ opaque. Field, petrography and geochemical evidences were used to know the genesis of igneous (ortho) or sedimentary (para) of these gneisses. All the evidences imply an igneous origin (ortho) for the studied gneisses. In fact, the protolith of these gneisses are porphyritic granite to monzonite rocks and has calcareous-alkaline and peraluminous nature. It can be inferred that the protolith of these rocks which formed in the late Neoproterozoic, belong to the calc-alkaline magmas in active continental margins or volcanic arcs (VAG). Further tectonic events have transformed them into gneisses.
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
S. M. Tabatabaei Manesh; M. A. Mackizadeh; saeideh ranjbar; R. Gholinezhad
Abstract
Javinan skarn is located at 115 km north west of Isfahan (40 km south of Kashan and east of Ghohrud), is included in Central Iran structural zone and spread in contact with Ghohrud granitoid (Middle Miocene age) with shale, sandstone and limestone succession of the Jurassic age known ...
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Javinan skarn is located at 115 km north west of Isfahan (40 km south of Kashan and east of Ghohrud), is included in Central Iran structural zone and spread in contact with Ghohrud granitoid (Middle Miocene age) with shale, sandstone and limestone succession of the Jurassic age known as Shemshak Formation. Skarnification is made up of endo- and exoskarn subzones. Wide mineralization in these skarns hasn’t observed. Endoskarn subzone has limited occurence (from a few millimeters to a few centimeters) and exoskarn has the greatest development (from 1 meter to more than 10 meters). Endoskarn with the formation of the skarn minerals garnet, pyroxene, plagioclase, epidote and sphene, is formed in the intrusive host rock and is in the vicinity of the carbonate part. In its immediate neighborhood, exoskarn subzone starts with the formation of minerals garnet, pyroxene, idocrase, epidote, phlogopite, chlorite, quartz and calcite in the carbonate section. Mineralogical studies and textural relationship of minerals have shown that the metamorphic facies اhas reached to pyroxene hornfels in skarn rocks of this area.
S. Alipour; Kh. Mosavi-ovenlegi; E. Hosseini; Sh. Aslanpour; Z. Haseli
Abstract
The Urmia Salt Lake as the largest hyper saline lake of the world is located between west and east Azerbaijan provinces, NW Iran. Geochemistry of trace and rare earth elements of bed sediments taken from 25 Cm of the lower most of 1.5 meters depth of drilled holes in 130 samples between 2014-2015 ...
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The Urmia Salt Lake as the largest hyper saline lake of the world is located between west and east Azerbaijan provinces, NW Iran. Geochemistry of trace and rare earth elements of bed sediments taken from 25 Cm of the lower most of 1.5 meters depth of drilled holes in 130 samples between 2014-2015 were investigated. General geochemical composition of samples revealed a very heterogeneous variation of major oxides at NW, NE, SW and SE parts of the lake. MgO, CaO and Na2O show a high enrichment compared to UCC, PAA and NASC values. Main minerals of the bed sediments include halite, calcite, ankerite, quartz, orthoclase, augite, hornblende and chlorite. The overall geochemical composition of sediments, resemble ferruginous shale and graywacke sandstone. Weathering in the various parts of the bed sediments is relevant to general climatological characters in the region. Rb and Sr among trace elements show high anomaly in respect to UCC, PAAS and NASC, while Eu indicated high depletion, especially at SW corner of the lake. Geochemical comparisons indicate the major role of different rock units in forming bed sediments rather than sediments carried by entering rivers to the lake.
H Atapour
Abstract
The Quaternary aeolian sands occur in northern and southern parts of the urban areas of the Kerman city. The important aeolian and interlayered sedimentary structures are cross- bedding and ripple mark. Diameter of the aeolian sands ranges from 0.06 to 2 mm, but coarse- grained (gravel size) alluvial ...
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The Quaternary aeolian sands occur in northern and southern parts of the urban areas of the Kerman city. The important aeolian and interlayered sedimentary structures are cross- bedding and ripple mark. Diameter of the aeolian sands ranges from 0.06 to 2 mm, but coarse- grained (gravel size) alluvial deposits are interlayered within the aeolian sands. Mineralogy and petrography of the aeolian sands indicate the presence of rock fragments (30 % carbonate, 25 % igneous and 5 % metamorphic rocks), silicate minerals (15 %) and non-silicate minerals (25 %). The Aeolian sands contain calcite (10%), quartz - chert (12%), alkali feldspar- plagioclase (5%), iron-titanium oxides (5%), clinopyroxene (2%), amphibole (1%) and gypsum (5%). Normative minerals include 30% calcite, 15.4% quartz, 12.5% orthoclase, 10% albite, 2.5% anorthite, 2% diopside, 1% enstatite, 4.6% clay minerals, 0.37% apatite, 3% gypsum, 3% hematite, 0.45% brookite and 10% dolomite. Major element composition of 22 aeolian samples analyzed by XRF and ICP-OES methods shows the frequent occurrence of calcium oxide and lower content of silica compared to the aeolian sands of other regions of the world, though the other major oxides are similar to the aeolian sands of Iraq, Saudi Arabia, Mexico and Namibia. Geochemical diagrams of K2O/Al2O3 versus Na2O/Al2O3and SiO2/Al2O3versus Fe2O3/K2Oand Na2O/K2O suggest a combined provenance of the igneous, metamorphic and carbonate sedimentary rocks for the aeolian sands around the urban areas of the Kerman city.
S. Younesi; M. R. Hosseinzadeh; M. Moayyed
Abstract
The Mahour Zn-Cu-(Pb-Bi-Ag) deposit located in central Lut Block, formed in an intensely crushed fault zone, dominantly in dacite-rhyodacite volcanic-subvolcanic unit of Late Eocene- Oligocene age. Mineralization occurred as veins, veinlets and breccia massive sulfide and/or as quartz , quartz-carbonate ...
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The Mahour Zn-Cu-(Pb-Bi-Ag) deposit located in central Lut Block, formed in an intensely crushed fault zone, dominantly in dacite-rhyodacite volcanic-subvolcanic unit of Late Eocene- Oligocene age. Mineralization occurred as veins, veinlets and breccia massive sulfide and/or as quartz , quartz-carbonate or quartz-muscovite (sericite)- carbonate vein-veinlets. Apart from negligible dark sphalerite, only fine-grained pyrite is observed as disseminated phase within the host rocks. Hypogene mineralization is complex and the main minerals, in order of abundance, are pyrite, Fe-bearing sphalerite and chalcopyrite, with subordinate galena, Cu-sulfosalts, Bi-sulfosalts, Fe-poor sphalerite, and afew greenokite, arsenopyrite, digenite and probably covellite. The Considerable amounts of Ag exist in lattice of some sulfosalt and sulfide minerals, as well as locally negligible Au-bearing W minerals. Mineralization is dominantly associated with sericitic, intermediate argillic and propyllitic alterations and rarely with advanced argillic and quartz- adularia that formed at three main stages including: 1- quartz- pyrite, 2- Fe- bearing sphalerite, and 3- chalcopyrite stage with sulfosalts and minor high sulfidation minerals. Mineralization occurred after silicification and disseminated pyritization that comprise tourmaline (sericitic alteration prior to mineralization) and then weathering process affected it. According to very low dissolution of Cu in Cu-Zn-S equilibrium system, high density of chalcopyrite inclusions in Fe-bearing dark sphalerites in Mahour reveals replacement origin of chalcopyrite disease texture. This texture and mineralogy (ore and alteration) indicate formation of Mahour polymetal mineralization at temperature range of 200-400°C and from an intermediate sulfidation state and low acidity fluid which was neutralized to alkaline by interaction with wall rock. Although, a minor evidence for evolution to high sulfidation state, more acidic and oxidation conditions is recorded in Cu- rich zone. Mineralogical features of the Mahour deposit indicate predominantly magmatic origin for mineralizing hydrothermal fluid, and in combination with mineralization structure, association with calc-alkaline to shoshonitic igneous rocks and tectonic setting of host rocks, are very similar to cordilleran style polymetal lode deposits.
S.J Moghaddasi
Abstract
Jeirud phosphate deposit is located about 45 km north of Tehran, in the central part of the Alborz geological-structural zone. This deposit is occurred in Jeirud Formation, which is one of the major hosts of phosphate deposits in Iran. Jeirud phosphate deposit is composed of several phosphatic sandstone ...
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Jeirud phosphate deposit is located about 45 km north of Tehran, in the central part of the Alborz geological-structural zone. This deposit is occurred in Jeirud Formation, which is one of the major hosts of phosphate deposits in Iran. Jeirud phosphate deposit is composed of several phosphatic sandstone (phosphorite) layers occurring in the laminated black shale unit of Jeirud Formation. Based on the petrographic studies, phosphatic layers of Jeirud formation have simple mineralogy. Phosphate mineralization mainly consists of apatite and quartz with subordinate calcite, dolomite, pyrite, iron oxides and clay minerals. Jeirud phosphate samples show similar REE patterns, total REE contents and element ratios, suggesting contribution of common processes in their formation. Average total REE contents of the Jeirud phosphate samples are much more than those in the average oceanic water. Normalized REE patterns of Jeirud phosphate samples show differentiation and enrichment in LREEs in comparison to HREEs. Ce anomaly was not distinguished in the deposit. Investigating chondrite normalized REE patterns of the Jeirud phosphates indicate their deposition under reducing conditions. Post Archean Average Shale (PAAS) normalized patterns of the Jeirud phosphates show a nearly convex pattern with moderate positive Eu anomaly, revealing an anoxic or (sulfate reducing) diagenetic environment for phosphate formation.
S Ranjbar; S.M Tabatabaei manesh; M.A Mackizadeh
Abstract
The Khuni skarn has been developed in the contact between small tongues of the Late Eocene-Oligocene I-type Kal-e kafi granitoidic intrusive body and the Precambrian Lakh marble-dolomite unit, Located 220 km northeast of Esfahan in the Central Iran structural zone. Skarnification could be divided into ...
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The Khuni skarn has been developed in the contact between small tongues of the Late Eocene-Oligocene I-type Kal-e kafi granitoidic intrusive body and the Precambrian Lakh marble-dolomite unit, Located 220 km northeast of Esfahan in the Central Iran structural zone. Skarnification could be divided into two subzones: endoskarn and exoskarn. There is no significant mineralization in relation to this skarn system. The extent of the endoskarn subzone is very limited (often from 2 mm to 2 cm), but the exoskarn has the most extension across the contact. The endoskarn subzone can be recognized by formation of euhedral garnets adjacent to the carbonate part. In the immediate vicinity of the endoskarn, the exoskarn subzone initiates with formation of garnet and clinopyroxene in the carbonates and is extended far away from the contact as represented by vesuvianite and phlogopite minerals. Garnet is one of the most abundant minerals in this skarn system and is found in different sizes and forms. In this paper, the zonation pattern of garnet crystals in the exoskarn subzone in the immediate vicinity of intrusive body is investigated. These garnets are mainly euhedral and isotropic and in some cases anhedral and anisotropic. They are commonly cored by a grossular-rich inner part, and a sharp considerable increase in their andradite content is found toward the rim in most cases. Most studies on skarn systems consider boiling to be the most important cause for this phenomenon. This means that boiling increases the Fe content and oxygen fugacity in the final stages of the system evolution, which consequently increases the andradite content of garnet in its solid solution
S Aghajani Marsa; M Emami; M Lotfi; k Gholizadeh; M Ghasemi Siani
Abstract
The mineralized veins at Nikuyeh are located south of the Tarom-Hashtjin metallogenic province in Alborz-Azarbayejan belt (West Alborz). Rhyodacite and andesite/andesitic basalt volcanic rocks are hosting the vein mineralization in the Nikuyeh ore district. Hydrothermal alteration in host rocks consists ...
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The mineralized veins at Nikuyeh are located south of the Tarom-Hashtjin metallogenic province in Alborz-Azarbayejan belt (West Alborz). Rhyodacite and andesite/andesitic basalt volcanic rocks are hosting the vein mineralization in the Nikuyeh ore district. Hydrothermal alteration in host rocks consists of propylitic, sericitic, argillic and silicic. Mineralization in Nikuyeh occurs in both hypogene and supergene forms in three stages: early stage includes pyrite, magnetite, chalcopyrite and bornite; middle stage includes galena, sphalerite and minor chalcopyrite, and late stage includes malachite, cerussite, covellite, hematite and goethite. Fluid inclusion studies on quartz and calcite show homogenization temperatures ranging between 185°C to 312°C and 133°C to 251°C, respectively. The salinities range from 0.5 to 5.5 wt% NaCl eq. in quartz and 0.3 to 5.4 wt% NaCl eq. in calcite. Boiling is supported by the occurrence of coexisting vapor-rich and liquid-rich inclusions, hydrothermal breccias, microcrystalline quartz, chalcedony and bladed calcite. Boiling and cooling are considered as the main mechanisms for ore deposition. Ore mineralogy, alteration assemblages and fluid inclusion data allow mineralization in Nikuyeh ore district to be classified as low sulfidation epithermal type.
S.J Yousefi; A Aftabi; A Moradian
Abstract
Gossan occurs considerably around the Chahar Gonbad copper-gold mine. The mineralogy of gossan includes: hematite (Fe2O3), goethite (FeO(OH)), and limonite (Fe2O3.H2O) with colloform texture, as wewll as quartz, calcite and clay minerals. Enrichment factors include: Ag=1.08, As=1.19, Bi=70.12, Mn=4.11, ...
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Gossan occurs considerably around the Chahar Gonbad copper-gold mine. The mineralogy of gossan includes: hematite (Fe2O3), goethite (FeO(OH)), and limonite (Fe2O3.H2O) with colloform texture, as wewll as quartz, calcite and clay minerals. Enrichment factors include: Ag=1.08, As=1.19, Bi=70.12, Mn=4.11, Mo=2.37, Pb=1.51, Sb=1.7 and Fe=1.71 in comparison to the mineralized rocks. However, Cu=0.03, S=0.03 and Se=0.04 are strongly depleted; Zn= 0.94 is slightly depleted. Based on correlation coefficients, four droups can be distinguished. The first group includes Bi, Cu and Sb which have a good correlation with Fe and Mn. The reason for this correlation is probably the adsorption of Bi, Cu and Sb by iron and manganese hydroxides - oxides in gossans. The second group comprises of Pb and Ag which have a good correlation with Bi, Cu, and Sb, without any relationship with Fe and Mn. The third group elements are As, Mo and Zn which have no correlation with Fe and Mn, as they form insoluble complexes. The fourth group includes sulfur and selenium which formed by sulfide weathering, gossan formation and sulfate minerals. The correlation of Bi with Cu is caused by weathering of sulfide minerals and formation of gossan. Bi, Cu and Au enrichments in the gossan are 3123.94, 12.62 and 400 times the clarck values. All the elements in the gossans, in particular Bi could be considered as the possible exploration guides around Chahar Gonbad area.
S Shahbazi; M Ghaderi; N Rashidnejad-Omran
Abstract
The Bashkand iron deposit is located in 16 km southwest of Soltanieh, in Central Iran Structural Zone. The rock units in the area include alternations of metamorphosed sedimentary rocks of the Kahar Formation, Khorramdarreh granite and an andesitic dike. The major alteration types are argillic, potassic, ...
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The Bashkand iron deposit is located in 16 km southwest of Soltanieh, in Central Iran Structural Zone. The rock units in the area include alternations of metamorphosed sedimentary rocks of the Kahar Formation, Khorramdarreh granite and an andesitic dike. The major alteration types are argillic, potassic, chloritic, sericitic and quartz-carbonatic in composition. N30-50W trend and S30-50W dip mineralization conforms primary bedding, foliation of phyllites as well as parallel faults. Mineralogical paragenesis includes: 1) Grossularite, pyroxene, idocrase; 2) Andradite, pyroxene, forsterite, phlogopite, magnetite; 3) Tremolite, serpentine, epidote, talc, biotite, magnetite, specularite and sulfides, and they have been cut by quartz-carbonate veins. The presence of magnetite synchronous with quartz and feldspar in the intrusive body, unconformity in behavior pattern of Fe2O3 with SiO2 and Al2O3, and its conformity with other major oxides as well as Cu and Zn, similarity of REE pattern in the ore, the intrusive body and skarnized host rocks as well as no similarity with the less altered host rocks, are the signs of sourcing ore from the intrusive-deriven fluids. Mixing of these fluids with meteoric water together with increasing in oxygen fugacity in the retrograde metasomatism stage led to ore mineralization.
M.A Arian; J Faslebahar
Abstract
Geochemistry, mineralogy and mechanism of the mud volcanoes located in the southwestof the Caspian Sea (Azerbaijan country) have already been studiedwith aim of finding out theirorigin, but mud volcanoes of The Gomishanhaven’t been studied from thesepoints of view yet. In this research, mudof mud ...
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Geochemistry, mineralogy and mechanism of the mud volcanoes located in the southwestof the Caspian Sea (Azerbaijan country) have already been studiedwith aim of finding out theirorigin, but mud volcanoes of The Gomishanhaven’t been studied from thesepoints of view yet. In this research, mudof mud volcanoes and sea floor sediments forthe first time weresampled and studied to discover their origin. The results of mineralogical and geochemical studies, which carried out byXRD, XRF, ICP methodsshow that main minerals of the Qarnyaryq, Naftlycheh and Incheborun mud volcanoes and of sea floor sediments are quarts,calcite and albite and sub ordinaryminerals are mainly halite and clay minerals such assaponite,natrolite and muscovite.Therefore,it can be resulted that the three mud volcanoes have a common origin. The obtained results compared with present data from Dashgil mud volcano(Azerbaijan) and chemical characteristics of the Caspian Sea water.This comparison revealed that the elements of Na,K, Ca, and Al in these three mud volcanoes are richerand Cl element is poorerthan the Dashgil mud volcanoand the Caspian Sea.
M Rasooli Bairami; B Shafiei Bafti; J Omrani; F Heydarian
Abstract
The occurrence of uranium anomalies associated with secondary Cu mineralization (malachite) at some parts of the Razgah metaluminous -peralkaline stock situated at the northeast of Sarab caused it to be a priority of Atomic Energy Organization of Iran (AEOI) to inspect the intrusion for likely uranium ...
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The occurrence of uranium anomalies associated with secondary Cu mineralization (malachite) at some parts of the Razgah metaluminous -peralkaline stock situated at the northeast of Sarab caused it to be a priority of Atomic Energy Organization of Iran (AEOI) to inspect the intrusion for likely uranium mineralization. Hence the current study, which is supervised by AEOI, was carried out to investigate the U mineralization potential of the stock by applying the mineralogical, petrological and geochemical studies. A fractionation trend is inferred from variations in rock compositions stretching from nepheline-bearing monzodiorite to nepheline monzosyenite, pseudoleucite monzosyenite and nepheline syenite. Consideration of geochemical features of fresh rocks of the stock and its associated dikes with emphasis on geochemical behavior of U and REEs during magmatic fractionation revealed that apatite has played a prominent role in controlling concentrations of REEs, U, and Th, in addition to zircon, which played a considerable role in accommodating HREEs, U, Th and HFSEs (Ti, Ta, Nb, Hf, Zr) in more differentiated rocks.Nepheline syenite rocks of peralkaline composition,s which are considered to be the most differentiated have low contents of HFSEs, U (up to 21 ppm), Th (up to 56 ppm) and REEs compared to average nepheline syenites but are relatively more enriched in these elements than less differentiated rocks of the stock. Most of the rocks possess negative Eu anomalies (Eu/Eu*≤1) and differentiated nepheline syenites have strong negative Eu anomalies. Abundance of ilmenite and magnetite and lack of amphibole in rocks suggests the parental magma had a reducing nature and meagre contents of volatile components, which along with metaluminous character and prepondarence of apatite in rocks have rendered the magma incapable of enriching U. Minor amounts of hydrothermal fluids released from some parts of the stock led to leaching of U from hosting minerals (apatite and zircon) and resulted in weak hypogene mineralization of U and Cu. Later supergene leaching process affected the weak primary mineralization and upgraded U tenors concurrent with formation of secondary Cu carbonate minerals. Due to thin and limited extention of these enrichment sites, they are not economically viable for uranium extraction; consequently, this area does not suggest for semi-detailed and detailed exploration program for uranium by AEOI.
N Etemad-Saeed; M Hosseini-Barzi; M.H Adabi; A Sadeghi
Abstract
The Kahar Formation at its type locality in the KaharMountain, 75 km NW of Tehran, consists of about 1000 m of siliciclastic rocks (mainly mudrocks). This study focuses on the mineralogical and geochemical composition of these mudrocks to identify possible source areas and their tectonic setting. The ...
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The Kahar Formation at its type locality in the KaharMountain, 75 km NW of Tehran, consists of about 1000 m of siliciclastic rocks (mainly mudrocks). This study focuses on the mineralogical and geochemical composition of these mudrocks to identify possible source areas and their tectonic setting. The optical microscopy and XRD studies suggest that the mudrocks are rich in quartz and feldspar (especially plagioclase) and have low phyllosilicates (mostly illite and chlorite). SEM-EDX petrographic investigation of mudrocks reveals that platy illite and chlorite may have formed during the diagenesis (illitization and chloritization). Classification of studied mudrocks based on the maturity index, indicate that they are tectic and phyllo-tectic types, deposited in basins related to an (continental) island arc tectonic setting. The Chemical Index of Alteration (average 70) and A–CN–K parameters indicate that a moderate chemical weathering has taken place in the source region of the Kahar mudrocks. In addition, the chemical composition of mudrocks suggests that the amount of sediment recycling is very low in the Kahar deposits. The geochemical discrimination diagrams, immobile trace element ratios and Rare Earth Elements of mudrocks suggest that the Kahar mudrocks were derived mainly from the felsic sources and deposited in the basins related to an island arc tectonic setting. The resulting model for the tectonic setting of the Kahar basin during the Late Neoproterozoic can be best explained by recently models that considered Iran as part of Peri-Gondwanan terranes, similar to the Avalonia and Cadomia arc terranes, occupying the northern margins of Gondwana.
F Kangarani Farahani; A.A Calagari; A Abedini
Abstract
Kambelu lateritic deposit is located in ~80 km west of Damghan, Semnan province. This deposit was developed as stratiform lenses along the contact of carbonates of Elika Formation (Triassic) and shale-sandstone of Shemshak Formation (Jurassic). Petrographical studies testify to the presence of collomorphic, ...
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Kambelu lateritic deposit is located in ~80 km west of Damghan, Semnan province. This deposit was developed as stratiform lenses along the contact of carbonates of Elika Formation (Triassic) and shale-sandstone of Shemshak Formation (Jurassic). Petrographical studies testify to the presence of collomorphic, colloformic, pseudo-porphyritic, and nodular textures within the ores of this deposit. Mineralogical data show that the ores contain diaspore, goethite, anatase, kaolinite, hematite, boehmite, and zircon. Considering the mineralogical composition and textural characteristics, this deposit was formed in an almost reduced near-surface environment. Geochemical indices like Eu/Eu* along with ratios such as Ti/Zr, Nb/Y, and Al/Ti suggest that Kambelu deposit is a product of alteration and weathering of rocks of trachy-andesitic to basaltic composition. Comparison of the variation trend of elements like Si, Al, and Fe within a selective profile reveals that the variation in chemistry (i.e., pH) of solutions responsible for lateritization and drainage intensity are the two principal factors for formation of the ores. Geochemical considerations show that distribution of trace elements in this deposit is a function of factors such as adsorption, scavenging by metallic oxides and hydroxides, fixation in neomorphic phases, and presence in resistant mineral phases. Inharmonic distribution of REEs in the studied profile indicates an allogenic origin for this deposit. The obtained data indicate that clays, anatase, zircon, xenotime, gorceixite, and churchite are the potential hosts for REEs in this deposit.
S Hojati; H Khademi
Abstract
There is no information about the occurrence and characteristics of sepiolite deposits in Iran. Thus, to identify and characterize the physicochemical and mineralogical properties of Eliyato deposits in northeastern Iran, 10 samples from different locations were taken and studied by powder X-ray diffraction, ...
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There is no information about the occurrence and characteristics of sepiolite deposits in Iran. Thus, to identify and characterize the physicochemical and mineralogical properties of Eliyato deposits in northeastern Iran, 10 samples from different locations were taken and studied by powder X-ray diffraction, scanning and transmission electron microscopy, X-ray fluorescence, thermal analysis, infrared spectroscopy, specific surface area and cation exchange capacity. The results indicated that these deposits consist of well-crystallized sepiolite (70–80%), with minor amounts of quartz (10–20%) and dolomite (5–10%). The electron micrographs of the samples showed sepiolite as a long interwoven fibrous mat, pore-filling and coating material. This textural evidence suggests direct chemical precipitation of sepiolite from an Mg-rich solution and/or after the precipitation of dolomite. The chemical composition, determined by X-ray fluorescence, indicated a Mg-rich mineral with the structural formula (Si11.97Al0.03) (Mg7.20Al0.11Fe0.15) O30 (OH)4 (H2O)4.8H2O. This suggests low isomorphic substitutions of Al for Si and Mg in the tetrahedral and octahedral sheets of the mineral, respectively. In addition, thermal analysis indicated four endothermic reactions at 134, 336, 546 and 818 °C which are associated with the gradual elimination of adsorbed and zeolitic water from the mineral structure. The associated weight losses are 8.69, 3.31, 2.65 and 10.19%, respectively. The high surface area of the material, compared to that of the Vallecas sepiolite deposit in Spain, suggests its suitability for industrial applications.
Seyed Javad Moghaddasi; Y. Negahban
Abstract
Robat Karim manganese deposit is located in 7 km northwest of Robat Karim (southwest of Teharan), within northeastern margin of Orumiyeh-dokhtar volcanic belt. Based on regional geology, the studied area is situated in the northern Saveh Eocene volcanic assemblage, composed of rhyolite, trachyte, andesite ...
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Robat Karim manganese deposit is located in 7 km northwest of Robat Karim (southwest of Teharan), within northeastern margin of Orumiyeh-dokhtar volcanic belt. Based on regional geology, the studied area is situated in the northern Saveh Eocene volcanic assemblage, composed of rhyolite, trachyte, andesite and basalt. Manganese mineralization is occurred as veins, in faults, joints and fractures that crosscut the volcanic rocks. According to mineralogical studies, the manganese ore of the studied area is composed of pyrolusite, psilomelane, ramsdelite and hollandite, as well as calcite and quartz. Intergrowths of manganese oxides and quartz (or calcite) associated with various open space filling textures support the epithermal origin of the ore forming fluids in this area. Geochemistry of major and trace elements in Robat Karim manganese ores, similarity of their chondrite normalized REE pattern with volcanic host rocks and other hydrothermal manganese deposits of the world, as well as negative Ce anomaly indicate a probable epithermal origin of the deposit. Ore forming fluids could be originated from meteoric and/or magmatic waters circulating through Eocene volcanic rocks, dissolve manganese and other metals and deposit them in fault planes and major fractures. High pressure of the ore forming fluid has caused the formation of brecciated trachyte.
R. Deevsalar; M. V. Valizadeh; V. Ahadnejad
Abstract
Granitic rocks of Malayer plutonic complex contain varieties of enclaves with different shapes, sizes, mineralogy andchemical composition. The interpretation of bivariant geochemical diagrams of major oxides and trace elements with respect to higher values of some of oxides such as MnO, TiO2, MgO, ...
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Granitic rocks of Malayer plutonic complex contain varieties of enclaves with different shapes, sizes, mineralogy andchemical composition. The interpretation of bivariant geochemical diagrams of major oxides and trace elements with respect to higher values of some of oxides such as MnO, TiO2, MgO, CaO& FeOt than host rocks in one groups of enclaves and moreover linear trend of these oxides and some of trace elements such as Ni, Cr, V indicate to different nature and mafic source of these enclaves (Mafic type) than host rocks and other enclaves (Felsic type).The study of chemical composition of this enclaves by using of univariant and bivariant statistical methods (bivariant regression analysis, correlation coefficients, cluster analysis and principle component analysis) indicate clear chemical contrast between mafic enclaves with felsic enclaves and granitic host rocks and in other side chemical affinity of felsic enclaves and their host rocks. Distinctive distribution of the majority of oxides and trace elements of mafic enclaves and host rocks and low values for R2 in regression analysis, low value of correlation coefficient of major element oxides and trace elements between enclaves and their host rocks, separate position of samples in cluster pattern and special direction of variants and samples of vectors in bivariant diagram of principle component analysis (PCA) are outputs of different geochemical characteristics of enclaves and host rocks. Moreover this correlates with different trends of each major oxides and trace elements in bivariant geochemical diagram (Harker diagram).
A. R. Ghiasvand; M. Ghaderi; N. Rashidnejad-Omran
Abstract
The iron deposits in north of Semnan are located in the south of Central Alborz structural zone. Stratigraphically, the area consists of Paleozoic to Quaternary rock series exposures. The area has been affected by Semnan, Darjazin, Attari and Diktash faults. An intermediate to acidic granitoid body of ...
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The iron deposits in north of Semnan are located in the south of Central Alborz structural zone. Stratigraphically, the area consists of Paleozoic to Quaternary rock series exposures. The area has been affected by Semnan, Darjazin, Attari and Diktash faults. An intermediate to acidic granitoid body of calc-alkaline and metaluminous composition, representing I-type granite characteristics, has intruded the Eocene volcanopyroclastic rocks in the north of Semnan. Skarn development and iron mineralization have occurred at the contact of the intrusive body and the volcanopyroclastic rocks. Mineral Paragenesis consists of magnetite accompanied by hematite, oligist, pyrite, chalcopyrite, garnet, pyroxene and epidote. Geometry of the ore bodies is massive, lenticular and vein type and their texture is disseminated, brecciated, vein-veinlet and massive. Dominant alterations in the area are propylitic, argillic, silicic, sericitic, chloritic and pyritic, respectively. The intrusive body has many similarities with intrusive bodies which form Fe-skarn deposits. Variations in the calculated parameters for REE indicate contribution of magmatic origin hydrothermal fluids to mineralization and that the intrusive body has had the dominant role as source of the skarn ore materials. Along with the intrusion, emplacement and crystallization of intrusive body, Fe-bearing fluids have intruded the volcanopyroclastic rocks, forming sodic metasomatism and deposited iron ores in the north of Semnan which have many similarities with calcic Fe-skarn deposits.
M. Abdi; Majid Ghaderi; N. Rashidnejad-Omran; A. Najafi
Abstract
Two cases of tungsten-copper vein-type mineralization have been studied in the Nezam-abad and Deh-hossein areas, in southwest of Shazand. The hydrothermal quartz-tourmaline mineralized veins have different host rocks (biotitic-granite and meta-sandstone). Considering similar ore metals (tungsten-copper-tin-lead-zinc) ...
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Two cases of tungsten-copper vein-type mineralization have been studied in the Nezam-abad and Deh-hossein areas, in southwest of Shazand. The hydrothermal quartz-tourmaline mineralized veins have different host rocks (biotitic-granite and meta-sandstone). Considering similar ore metals (tungsten-copper-tin-lead-zinc) in the Nezam-abad and Deh-hossein areas, same mineralogy of veins (quartz-dravite) and similar REE variation patterns in the two areas, it is suggested that the Nezam-abad and Deh-hossein mineralized veins have the same origin. It means, when the Br-bearing fluids were active, they caused the quartz-tourmaline vein-type mineralization in this area. Considering the barren intrusions in the area and other mineralogical-geochemical evidences in this study, it could be concluded that tungsten and other metallic elements in the Nezam-abad and Deh-hossein ore-bearing veins have a sedimentary/metamorphic origin.
A. Akbarpour; A. Rasa; M. Mehrpartou
Abstract
The Masjeddaghi area is a part of Alborz-Azarbaijan Zone and located in the Jolfa 1:100000 geological map sheet. The oldest rock units cropped out widely in the south and northeast of the area belong to the Eocene flysch-type sediments. The other outcrops consist mainly of volcanic rock complex of andesites ...
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The Masjeddaghi area is a part of Alborz-Azarbaijan Zone and located in the Jolfa 1:100000 geological map sheet. The oldest rock units cropped out widely in the south and northeast of the area belong to the Eocene flysch-type sediments. The other outcrops consist mainly of volcanic rock complex of andesites and trachyandesites affected by quartz monzonite intrusion and caused alteration of phyllic and carbonate phyllic type. The mineralization in volcanic complex is also accompanied by quartz and barite veins. The study of alterated zone around veins shows sericite, silicified, prophillitic, chloritic and alunite (jarosite) alterations. Investigation of alteration zones around mineralized veins shows epithermal gold ore in which alunitic alteration (jarocite) is the most important characteristics. The result of the study on alteration and extension of altered zones in the whole study area give rise to the probability of porphyry type copper deposit (potassic, phyllic, argillic and prophylitic alteration zone).
