Iranian Journal of Crystallography and Mineralogy
Year:2020 | Volume:28 | Issue:1|Papers Count:18

Niaz area is located at the Alborz-Azarbaijan magmatic zone in the northwest of Iran. All of the rock units in this area are composed of intermediate to acidic igneous rocks of Oligocene to Miocene age. Based on geochemical data, the mineralized monzonitic rocks in this area belong to high-K calc-alkaline and shoshonitic magma series, has a metalauminous to slightly peraluminous nature and belongs to the active continental margins and post-collision tectonic settings. Enrichment in LILE and LREE elements and depletion of HFSE and HREE elements are the main characteristics of these rocks. Geochemical features such as high SiO2 and Al2O3, low MgO, low content of Y (9. 9 to 18. 6 ppm) and Yb (0. 83 to 1. 53 ppm), high values of (La / Yb)N (23. 43 to 64. 82), high Sr content (mean ~ 719. 74 ppm), and low content of HFSE elements indicate the adakite affinity of these rocks. In general, the geochemical properties of the samples are similar with the high-silica adakites (HSA). High ratios of Sr/Y and (La/Yb)N indicate the presence of amphibole and a small amount of garnet as stable phases in the source region of magma and it seems that the parent magma of studied adakite rocks is formed from the partial melting of the thickened lower continental crust.

The intrusive body of the Shahrak is located between the West Azarbaijan and Kurdistan provinces. Lithologically, this intrusive body consists of granodiorite, monzonite, monzodoirite and monzogobbro, which intruded into Oligo-Miocene sedimentary units and Cretaceous and Precambrian metamorphic rocks. Mineral chemistry studies of granodiorite and monzogabbro rocks show that plagioclases have labradorite to bytownite composition, and clinopyroxenes are augite. Thermobarometry calculations of pyroxene minerals indicate that the formation temperature of these minerals ranges between 900 to 1250 oC and the crystallization pressure of clinopyroxenes is estimated to be about 6 to 10 kbar. The geochemical investigations of the whole rock indicate that the magma has metaluminous and calc-alkaline affinity. In the multi-element spider diagram normalized to condrite and primitive mantle, there is a significant enrichment of LREE than HREE and depletion of Ti, P, Ta and Nb, which is a characteristic feature of the volcanic arc rocks of the subduction zones. Also, based on different tectonomagmatic diagrams, these rocks are located in the active continental margin environment. Based on REE elements, the parental magma of the studied rocks is probably originated from an enriched mantle.

Aplitic and pegmatitic dykes exposed in southeast of Hamedan in the Simin area. From the margin to the center of these dykes, two typical textural areas present that obviously indicate effect of crystallization progress: 1-In the marginal zone, fabrics consist of anisotropic textures of the outer zones, including fine-grained units, graphic intergrowths, and unidirectional solidification textures and 2-In the interior zone that have coarse, blocky textures. Microprobe analysis performed on tourmaline, plagioclase and K-feldspar minerals. Tourmalines have schorlite composition. In the FeO/(FeO+MgO) vs. MgO diagram that determine origin of tourmalines, the studied tourmalines have Fe# between 0. 8 to 1 that indicates they formed in magmatic conditions and external hydrothermal fluids and don’ t take part in their genesis. Compositions of analyzed plagioclases are albite-rich (Ab90-100) and K-feldspars have 92-97 percent K-feldspar. This indicates progress of fractional crystallization which is related to magma. Studied of tourmaline zoning is well visible at thin sections and in the chemical analyses. In the analyzed feldspars, high amount of Rb (1319 ppm) and also Cs (205 ppm) indicate high degree of fractionation which is related to magma.

The Lakeh-Siah iron± apatite deposit is located in the Bafq-Saghand Metallogenic Province (Central Iran) and situated within rhyolitic rocks. Magnetite with minor apatite are the main ore minerals in this deposit. Monazite and xenotime minerals in microscopic scale formed as inclusion in the apatite and magnetite crystals and micro-fractures. Based on microscopic and EPMA evidences, apatite is primary mineral and has been scavenging from mafic to ultramafic magma affinities. Apatite crystals are shows irregular zoning from dark and bright phases, then the dark portions mostly enriched in secondary monazite and xenotime inclusions. These results are consistent with the dissolution-reprecipitation process. During this process, apatite crystals reacted with secondary hydrothermal fluids along the crystalline boundaries and have depleted from REE and also due to this process, REEs have been undergone preferential differentiation, LREE and HREE enriched in monazite and xenotime, respectively.

The Gol-Gohar metamorphic complex, a part of east Sanandaj-Sirjan zone, is located 55 km southwest of Sirjan. This complex consists of metapelitic, metapsammitic, and metacarbonatic rocks. Field and geochemical evidences indicate that these sedimentary protolith sequences are composed of shale and sandstone with alternation of carbonate layers in the upper parts. In the studied metapelites, garnets are almandine-rich. Composition of biotite ranges between sidrophyllite and annite and plagioclase varies from albite to anortite (in amphibolite and garnet amphibolite). Oligoclase and andesine are present in schists. Our studies show that amphibolite and garnet amphibolite are types of para amphibolite. The results of thermometry, based on the garnet-biotite pair and barometry through GBPQ method, for these rocks demonstrate that Gol-Gohar metapelite schists were formed within a temperature range of 550-578˚ C and a pressure range of 3. 7-4. 6 kbar (greenschist and lower amphibolite facies). The thermo-barometry studies, based on chemistry of amphibole mineral in the amphibolites and garnet amphibolites, demonstrate 589-613° C and 613-641° C temperatures, 4. 7-4. 9 kbar and 4. 3-5. 6 kbar pressure ranges respectively which are indicating of amphibolite facies metamorphic conditions for these rocks. Field evidence and geochemical studies indicate that the evolutionary trend which resulted to the increasing of temperature and pressure from schists to amphibolites and garnet amphibolites are consistent with the mineral paragenesis.

Momen Abad mining district is a part of Eastern Iranian bentonite zone, located in Eocene-Oligocene volcanic belt. Mineralogical study of bentonites by XRD method introduced smectite and cristobalite as major mineralogical phases and plagioclase, alkali feldspar, paragonite, zeolite (heulandite and clinoptilolite), mica-illite, and quartz as minor phases. SEM imaging of bentonites shows that platy particles of bentonites form flocculated aggregates and occur as rounded and angular particles with cornflakes texture. Energy-dispersive X-ray spectroscopy indicates that bentonite aggregates are of Na-montmorillonite type. The rheological test results reveal that the apparent viscosity, plastic viscosity, yield point, and gel strength of simple bentonites of 30. 4 g weight is higher than that of samples with 10. 8 and 22. 4 g weight; however it is not in accordance with API standard therfore is not appropriate for drilling industry. Rheological characteristics and gel strength for activated samples are better than the simple samples. It is noteworthy that fluids containing carboxymethyl cellulose polymer is the best material to increase the rheological characteristics of bentonites among the polymers due to high ionic properties of particles and they are applicable in oil drilling industry (samples B02 and B04). However, sample B07 with all additives is not compatible with API standard of drilling qualification. Among three bentonite samples, the rheological properties of apparent viscosity, plastic viscosity, yield point, and gel strength in 10 seconds and 10 minutes in simple bentonite of B02 with 30. 4g weight are 8. 5, 5, 7, 5 and 5 respectively and will be increased to 25, 9, 32, 14 and 11 respectively with carboxymethyl cellulose polymer showing the highest quality in accordance with API standard and is appropriate for drilling industry.

Samsour ophiolite is located in Sistan and Baluchestan Province, about 210 Km southwest of Zahedan city. Based on structural and sedimentary classification of Iran, this ophiolite is located adjacent to NosratAbad-Karvandar fault and belongs to Sistan suture zone. Rock units of this ophiolite are mainly composed of ultramafic, including gabbro (Layerd and massive) and doleriteic. In the microscopic studies, igneous rocks include lherzolite, gabbro, olivine gabbro and diabase which have granular, network, cumulale, porphyrytic and ophitic textures. In the geochemical classification diagrams, these rocks are often plotted in the gabbro and picritic gabbro. Also, tectonomagmatic diagrams show magma that formed this ophiolite rocks are belonging to MORB. The REE elements are normalized to Chondrite and MORB show LREE to HRRE has enrichment and compard with E-MORB and N-MORB is enrichment, which is more closed to E-MORB. The study of sequences, cumulative crystals in the layer of gabbro, shows the order of crystallization of olivine, plagioclase and clinopyroxene that is more similar to the crystallization of MORB magma.

In order to understand the cause of coloration of fluorites, following experiments (UV-spectroscopy, irradiation by gamma ray and thermal bleaching) carried out on the colored and colorless fluorites from the mines of Mazandaran Province. All colored and colorless fluorites have absorption band in UV part of electromagnetic waves but deep-violet and brown fluorites have an absorption band in visible range, whereas colorless and white varieties have not shown any absorption bands. Irradiation of colorless fluorites by gamma-ray caused a new absorption bands in UV-visible range. Thermal bleaching of the deep-violet fluorite reduced its color to pale-pink color and also pale-violet colored fluorite changes to colorless ones. Chemically, deep-brown and deep-violet fluorites show (1) the maximum total concentration of rare earth elements (Σ REEs= 20 ppm), Y (9 ppm and 3. 5 ppm for deep-brown and deep-violet fluorites, respectively) and (2) total concentration of radioactive elements (U+Th= 2. 8 ppm and 7. 9 ppm for deep-brown and deep-violet fluorites, respectively). Based on this study, lattice defects in crystal structure of fluorites due to U and Th decay were caused the color centers (F-centers) as most important cause of fluorite coloration. This was confirmed by gamma-ray irradiation and color bleaching experiments.

Dardvey iron skarn ore deposit is located in the central part of the Sangan mininig area, northeastern Iran. In this study, silicate geothermometr were used to estimate the formation temperatures of skarn zones in Dardvey Fe-skarn deposits. The main metamorphic minerals in prograde and retrograde skarn zones are garnet-clinopyroxene-tremolite/actinolite-amphibole-chlorite-epidote-feldspar-phlogopite-dolomite. Two feldspar geothermometry indicate that endoskarn zone in Sarnowsar granite form at temperatures between 635 to 725 ° C, which is not consistent with fluid inclusion tempertures. Based on clinopyroxene-garnet geothermometry, temperature of 300 to 505 ˚ C was calculated for prograde skarn stage. Chlorite and Ca-amphibole geothermometry of retrograde zone indicates temperature of 200 to 290 ° C and 200 to 300 ° C respectively. Silicate minerals geothermometry of prograde and retrograde skarn zones are in accordance with fluid inclusion data. Both geothermometery methodes of prograde and retrograde skarn zones indicate that contact metamorphic sakarn development occuured in <600 ˚ C that is consistent with hornblende hornfels facies.

The Kahrizbeyg pluton is located northwest of Iran in Central Iran zone. It is emplaced into the Cretaceous limestones in which contact metamorphism has happened. Meanwhile, rock fragments of this pluton are found in conglomerate units of Early Oligocene Lower Red Formation. Therefore, the relative age of pluton is between Cretaceous and Oligocene. The Kahrizbeyg pluton consists of granite and granodiorite which granodiorite is the dominant rock type. Major rock forming minerals of this pluton are quartz, plagioclase and K-feldspar along with mafic minerals of biotite and amphibole and accessory minerals of sphene, apatite and opaque minerals. Chlorite and calcite are also present as secondary minerals. Sieve texture, sphene ocellar texture, mafic clots, amphibole reaction rim around biotite and bladed biotite crystals are the textural characteristics of this pluton which have been probably generated by magma mixing in the study rocks. Abundant mafic microgranular enclaves in some parts of the Kahrizbeyg pluton also support this idea. Chondrite normalized REE patterns of the study rocks are relatively smooth and show enrichment in LREEs relative to HREEs. LREEs enrichment is due to low degree of partial melting, high abundance of these elements in the source or crustal contamination. In the spider diagrams, LILEs such as Rb, Th and K and some of the LREEs show enrichment relative to HFSEs like Yb, Sm, Zr, Ta and Nb. Positive anomalies of the elements Rb, Th and K are due to the magma mixing between crustal and mantle magmas or crustal contamination. The negative anomalies of Ti and Nb-Ta are characteristic to the subduction related magmatism. Also it can be due to lack of these elements in the source or crustal involvement in the magmatic processes. Based on petrography and geochemistry, the Kahrizbeyg pluton is a metaluminous, calc-alkaline, I type granite which has been generated in the active continental margin setting due to the subduction of Neotethys oceanic lithosphere beneath the Central Iran microcontinent.

Newly minerals could be formed as a result of oxidation, hydrolysis, precipitation and dehydration processes in acid mine drainage (AMD) environment. The occurrence of secondary minerals within the dump No. 7 from Miduk copper mine was studied using mineralogical approaches including X-ray diffraction (XRD), Scanning Electron Microscope (SEM-EDS) and Raman Spectroscopy (RS). Geochemical invetigations, including saturation index and speciation, were conducted on pore water of the dump which simulated from paste pH test. Acidic pH value (ranges from 1. 47 to 4. 23), a high concentration of SO42-(ranges from 3. 95 to 286 g/L) and a high level of Fe (varies from 120. 9 to 70860 mg/L) of the waste leached indicate that sulphide oxidation especially pyrite occurs within the dump. Complex FeSO4+ was dominant species of ferric iron in the leached solution phase. According to mineralogical and geochemical studies, newly formed minerals including coquimbite, ferricopiapite, plumbojarosite, rozenite, alunogen and brochantite were identified within the dump. Retention of As, Pb and Cu by iron sulphate, especially coquimbite, were confirmed in the dump. The results of the present study could be employed to develop a comperehensive environmental management program at the mining sites.

Sangan iron mine with skarn type genesis is located in NE Iran (Khorasan Razavi Province), in the Central Iran zone and NE of Lut Block sub-zone. The Senjedak-III prospect area is one of the six eastern anomalies of Sangan iron mine that encompasses eastern terminal of Khaf-Kashmar-Bardaskan volcano-plutonic belt. The geology of this area consists of a series of igneous (dykes and intrusive bodies), metamorphic (skarn, slate and phyllite) and sedimentary rocks (sandstone, limestone and dolomite). The Senjedak complex is an exo-skarn and includes mineralization such as magnetite, pyrrhotite, chalcopyrite, pyrolusite, pyrite, arsenopyrite, hematite, goethite, limonite and malachite. Sulfide mineralization is associated with retrograde skranification stage whereas oxides/hydroxides mineralization is in connection with fault zones. Ground magnetic surveys show three magnetic anomalies of A, B, and C in the area. The A and B abnormalities have deep origin and may be related to each other. Separation in these abnormalities is attributed to the activity of secondary faults. The C magnetic anomaly that is consistent with the magnetite outcrop in the eastern parts of the range is weaker and has no deep-seated origin. The results of this research can be used to continue exploratory operations at deep anomalies.

The pre-Eocene Allahyarlu ophiolitic-metamorphic complex is exposd in the core of the Allahyarlu anticline in the northwest of Iran and northeast of Meshginshahr. This complex consists of a variety of schist, gneiss, amphibolite and metadibase rocks with serpentinite and tectonic slices including gabbro, dunit, marble and diabase. Amphibolites can be divided into garnet-free amphibolite and garnet amphibolite. Hornblende and plagioclase are the main phases in the garnet-free amphibolite. Titanite, calcite, rare biotite, epidote, Fe-oxides and zircon constitute the minor phases. In garnet amphibolites, in addition to these minerals, garnet is also present. Porphyroblastic and nematoblastic are the common textures in these rocks. The study of mineral chemistry and determination of temperature and pressure conditions of amphibolites are the subject of this study. Based on the results of microprobe analyses in garnet-free amphibolites and garnet amphibolites, the amphiboles are of magnesium hornblende and tschermakite types, plagioclase composition ranges between andesine and albite, and in garnet amphibolites garnet has an almandine-rich nature. Based on the variations of Ti versus total Al (Alt), the studied amphiboles in the amphibolites of the Allahyarlu metamorphic complex are medium pressure amphiboles. The results of thermometry and barometry calculations on these rocks, based on the chemistry of amphibole, garnet and plagioclase, were obtained. The P-T estimates indicate an average pressure of 8Kbar and temperature of 600C for the peak of metamorphism. This is in accordance with Barrovian metamorphic gradients, indicative of crustal thickening (in volcanic or island arcs) or a collisional tectonic setting.

Chah Zard granitoid pluton with 535. 4± 3. 2 Ma age (U-Pb zircon method, carried on the Zircon) intruded into Jandagh – Arousan metamorphic complex, and strongly mylonitized during later events. For the first time, Chah Zard granitoid pluton investigated by anisotropy of magnetic susceptibility (AMS) method. Mean magnetic susceptibility (Km) of biotite granites (the main constitute of Chah Zard granitoid pluton) is 112 µ SI. Biotite is the most important magnetic carrier in biotite granites. During of mylonitization, considerable volume of biotite alterated or evolved to muscovite and then Km values of their bearing rocks strongly decreased. Magnetic lineation and foliation have low plunge and dip, respectively, and also field evidences confirmed this finding. Magnetic lineations, mostly oriented toward northwest. Since the intensity of mylonitization is very high, microstructures which resulted in relation to tectonically stresses, had overcome to magmatic microstructures and partially to completely oblitrated them.

The Kalchuye Cu-Au deposit is located in the central part of the Urumieh – Dokhtar magmatic arc. This mineralization is mainly hosted by diorite, quartz diorite and andesite rocks. The mineralization is characterized by chalcopyrite, pyrite, galena and magnetite in the hypogen stage followed by chalcocite, covellite, malachite and goethite in supergen stage. According to the geochemical studies, the Lan/Ybn ratio is between 2. 2 to 6. 3 and Eu/Eu* varies from 0. 7 to 1. 1; so that intrusions which are the host of mineralization in the Kalchuye region represent characteristics of magmas in the subduction zone (enrichment of LILE, depletion of HFSE in association with negative Ti anomaly). Fluid inclusion data show the temperature of 150-310 ˚ C, salinity of 0. 1-4 (wt%NaCl eq. ) and depth of 400m, approximately, for the Klchuyeh deposit. Fluid evolution in the Kalchuye exhibits cooling, surface dilution and boiling. Evidences such as bounded and comb textures in quartz, bladed calcite, hydrothermal breccia, propelitic alteration and fluid inclusion information such as temperature and salinity prove the low-sulfidation epithermal nature for the Kalchuye deposition.

Do-Chah metamorphic-igneous complex is one of the Iranian crystalline basement complexess which is located in the SE Shahrood in northern edge of Central Iran structural zone. This complex includes a wide compositional range of metamorphic rocks such as metabasite, metapelite, metacarbonate and metapsammite, and meanwhile is host of leucogranite and biotite granite intrusions. Protolith of metabasites has been basaltic lava flows, diabasic swarm dikes and small-scale gabbrodioritic intrusions which metamorphosed to greenschist, amphibolite and garnet amphibolite in a high pressure barrovian metamorphic path. Thermobarometry calculations, based on the microprobe analyses of coexisting amphibole-plagioclase pairs in metabasites, indicate a P-T range of 387-636 ° C a nd 2. 7-11 Kbar pressures for stopping of exchange and final equilibration. These conditions reveal a medium to high pressure barrovian metamorphic regime during the Cadomian orogeny in the Iranian Gondwana terrains from greenschist to upper amphibolite facies.

Mashkan deposit is located northern Soltanabad, Sabzevar, Khorasan Razavi province, and tectonically, between Eastern Alborz zone, north Sabzevar ophiolite zone and Binalood zone. Geology of the area includes sedimentary rocks like sandstone, limestone, conglomerate, shale, marl and Eocene volcanic units. Barite mineralization as vein-veinlets with the mainly NW-SE trend has cut off the rock units. Minerals consist of barite, quartz and calcite associated with galena and secondary minerals such as goethite, limonite and malachite. Quartz is the most important waste mineral. According to fluid inclusion studies, formation temperature of mineralization is between 235 to 330 º C and it is occurred from NaCl-, and CaCl2-bearing fluid with 20. 67 to 21. 4 wt. % NaCl equivalent salinity. Based on geology, mineralization, and geochemistry, Mashkan barites are hydrothermal type.

The In-doped vanadium pentoxide nanostructures with different doping levels including 0, 10, 20 and 30 at. % were prepared by the spray pyrolysis technique. The prepared thin films were characterized by the x-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results revealed that the films were crystalline in tetragonal phase. Increasing the In-doping level made the structure more disordered and decreased the crystallite size up to more than 50% for V2O5: In30at. % with respect to the pristine sample. The SEM results showed single phased nanorod-and nanobelt-shaped V2O5 structures with average diameters of 50-100 nm. The Hall effect measurements showed that all the involved films are n-type semiconductors whose resistance increases with In content; this also can be related to the enhanced structural disorder of the samples.