Iranian Journal of Crystallography and Mineralogy
Year:2019 | Volume:27 | Issue:2 |Papers Count:21

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 evidence indicate that these sedimentary protolith sequences were composed of shale and sandstone alternation with carbonate layers in the upper parts. In the studied metapelites, garnets are almandine-rich, composition of biotite is between sidrophyllite and annite and plagioclase varies from albite to anortite (in amphibolite and garnet amphibolite) and oligoclase and andesine (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 oC and 613-641 oC temperatures, 4. 7-4. 9 kbar and 4. 3-5. 6 kbar pressure ranges respectively which are indicating amphibolite facies of metamorphic conditions for these rocks. Field evidence and geochemical studies indicate that the evolutionary trend which resulted increasing temperature and pressure from schists to amphibolites and garnet amphibolites are consistent with the mineral paragenesis.

Freezi Lead-Zinc-Copper prospect area is located in north east Mashhad in Khorassan Razavi Province. Mineralization was formed in the area as vein type in the host rocks of slate with interlayer of phyllite and meta sandstone of Upper Triassic to Early Jurassic age (equivalent to Shemshak Formation). The only alteration in the host rock is silicification. Primary minerals are quartz, galena, chalcopyrite and pyrite, while secondary minerals are hematite, goethite, limonite, malachite and azurite. The amount of Pb is up to %3. 7, Zn is up to %1. 6, Cu is up to %4 and Ag 183 ppm. Micro thermometry measurements of two Phases (liquid and vapour) showed that quartz and ores originated from a fluids with mid to high temperature (200 to 347° c) and high salinity (20. 2 to 22. 35 wt%) which was probably metamorphic liquid. Reduction of temperature of the liquid had greatest importance in Pb, Zn, and Cu mineralization. IP/RS data on the location of Gossan zones, veins, previous digging, and geochemical anomalies showed increasing in chargeability. Mineralization occurred in three part (A, B, C) in the area. In view of mineralization, geochemical anomalies and chargeability in the part B is more important than A and C. Studies of drill cores over the psedousection IP/RS anomaly in part B showed the presence of graphitic coal in the country rocks which is the causative source of anomaly. Based on geology, mineralization and fluid inclusion characteristics, the type of mineralization in the Freezi area is orogenic. Possibly metallic elements originated from the graphitic layers and during the Middle Jurassic orogenic phase, middle Cemmerian, transported by metamorphic water and deposited in places of suitable structure.

The Lar igneous complex (LIC) is located in the Sistan Suture Zone. The igneous rocks occur as stock, dike, lava and pyroclastic. As a result of hydrothermal fluids, Cu-Mo mineralization was formed in the stocks. Apatite is one of the most abundant accessory minerals in the igneous rocks that occurs as prismatic and brecciated. EPMA data indicate that apatites are fluorapatite in composition with low contents of chlorine indicating they were equilibrated with a relatively hydrous and oxidized melt/fluid. The mentioned melt/fluid fall in the field of the worldwide mineralized systems. The low chlorine contents of the apatites and high-K (shoshonitic) character of their host rocks indicate Cl– K decoupling of the primary magma due to involvement of dehydrated sediments in the deep lithospheric mantle source and occurrence of fractional crystallization.

The Zaraj-Sou bauxite deposit (southwest of Ramsar, Mazandaran Province, northern Iran) was developed as discontinuous stratified layers and/or lenses along the boundary between carbonate rocks of the Elika (Triassic) and shales and sandstones of the Shemshak (Lower Jurassic) formations. Diaspore, kaolinite, hematite, and anatase are the major mineral phases of the ores. Texturally, the bauxite ores have typical textures of clastic, rounded-grain, and nodular which are often accompanied by certain forms of concretions, ooids, and pisoids in restricted quantities. Concentration values of REEs within the ores in the selected profile vary from 149. 97-348. 10 ppm and the ratios of Eu/Eu* and Ce/Ce* are within the range of 0. 75-1. 04 and 0. 64-1. 28, respectively. Investigations showed that changes in the values of these parameters are controlled by degree of scavenging hematite. The calculation of mass changes of elements and the study of the trend of variation of elemental ratios in a selected profile across this deposit revealed that the distribution of REE in ores is a function of factors such as changes in pH of ore-making solutions, presence of carbonate bed rock as an active buffer, co-precipitation with metallic oxides, and fixation in neomorph mineral phases. Correlation coefficients among elements suggest that minerals such as hematite and secondary phosphates are the potential hosts for lanthanides in the studied ores.

The Esmaeilabad granitic body with the Late Triassic age is situated in the central part of the Posht-e-Badam block (Central-East Iranian Microcontinent), in the northeastern of the Yazd Province. This granitic body cross cut the metamorphic rocks of the Posht-e-Badam complex and covered by the Cretaceous limestone. Rock forming minerals of the studied granites are K-feldspar (orthoclase), plagioclase (andesine, oligoclase), quartz, amphibole (magnesio-hornblende), biotite, apatite, titanite and zircon. According to the mineral chemistry analyses, amphiboles represent the igneous nature. Biotites are rich in Magnesium. Chemical characteristics of biotites indicate that they are primary biotites which are generated by calc-alkaline magma. Chemical composition of the amphiboles and biotites in the Esmaeilabad granites suggest that they belong to the I-type granites and generate in an environment with high fO2. Geothermobarometry estimations yield temperatures between 550 to 700 oC and pressures in the range of 2 to 3. 8 kbar. Based on the geological position and age of the studied rocks, generation of this granitic body can be related to the subduction and closure of the Paleo-Tethys Ocean in the western part of the Central-East Iranian Microcontinent, which can be the reason for granitic plutonism in this area.

The Malayer-Boroujerd-Shazand district (approximately 70 km long) is located in the Sanandaj-Sirjan zone with NW-SE trending, and consist mainly of hornfels, schist, phyllite, migmatite, granite and granodiorite which contain numerous pegmatite and aplitic dykes. Among these rocks, granodiorite, hornfels and schist are main host rocks for quartz, feldspar, muscovite and tourmaline bearing pegmatites. The tourmaline composition is schorlite-foitite type with tendency to dravite in Shazand tourmaline which show magmatic-hydrothermal origin, and located in alkali and site-vacancies. These tourmalines in the Fe/ (Fe + Mg) vs MgO diagram are located above and below 0. 8 which proved tourmalines are magmatic and hydrothermal. Magmatic evidences are dominantly schorlite tourmaline composition, increase in octahedral Al content, higher Fe content than Mg and presence of more sample between alkali-deficient and proton-deficient tourmaline vectors. Presence of zoning in tourmaline, vein form pegmatite, increase of Mg in some samples and being away from alkali-deficient and proton-deficient tourmaline vectors are evidences for hydrothermal origin of tourmaline.

The Muteh-Golpayegan metamorphic complex consist of different metamorphic rocks including pelitic, semi-pelitic, carbonate, quartz-feldspathic and basic metamorphosed rocks. The metapelitic rocks include chlorite schist, biotite schist, garnet schist, staurolite schist, kyanite schist, sillimanite schist and andalusite schist. The semi-pelitic rocks contain higher amounts of quartz and lower amounts of mica. Apart from the main minerals in the rocks, which are quartz, muscovite, biotite, chlorite, garnet, staurolite, sillimanite, kyanite and andalusite, some samples contain considerable amounts of tourmaline as minor mineral. Tourmaline was studied in one pelitic sample and one semi-pelitic sample with high quartz content. Tourmaline in both lithologies contain high amounts of Na+K relative to Ca in the X crystallographical site, indicating alkaline tourmalines for the studied samples. Low Ca contents points to low uvite content or limited Ca(Fe, Mg)(Na, Al)-1 substitution. The Al content is higher than 6 atoms per formula unit (6. 519-6. 968), making them Al-bearing tourmalines. Tourmaline in the pelitic samples is schorl, with igneous origin from detrital tourmalines in granitoids, while tourmaline in semi-pelitic sample is dravite with metamorphic origin, more likely formed during regional metamorphism in the Golpayegan area.

The Zailic gold-bearing veins are located in the Arasbaran metallogenic zone, east of Ahar, East-Azarbaidjan Province. The most important lithologic units in this area are andesitic and trachy-andesitic tuffs and lavas of Upper Eocene age hosting vein-type gold mineralization. Theses rocks have suffered silicic, argillic, phyllic, and propylitic alterations brought about by hydrothermal fluids. The geochemical study of alteration zones in this area showed that in the silicic zone, due to the acidic nature of altering fluids and hence intense leaching, depletion of most major and trace elements took place. The degree of leaching towards the propylitic zone, owing to the pH increase of the hydrothermal fluids, gradually decreases. The presence of minerals with high adsorption capacity, such as clay minerals, resulted in concentration and fixation of many elements in the argillic, phyllic, and propylitic zones. Consideration of the behavior of rare earth elements (REE) in silicic zone relative to almost fresh volcanic rocks showed that most of REE suffered depletion. Geochemical indices such as TiO2 and (Ce + Y + La)-(Ba + S), showed that the hypogene hydrothermal fluids played an important role in the development of alteration zones at Zailic.

The Ravanj intrusive, with tonalite, quartz-diorite, and microquartz-diorite composition, is exposed in the West of Ravang Village, NE Delijan, in Urmia-Dokhtar zone. Plagioclase is observed in three different sizes (coarse, intermediate, and microcrystalline) in the composition of in Ravanj intrusive. Most of the coarse crystals are zoned while intermediate and microcrystalline show polysynthetic and pericline twins. The lack of inclusions in the center of plagioclase and An versus K2O with a linear trend indicate that plagioclase is the main magma phase. The chemistry of polysynthetic crystals is in the range of An30. 96 to An58. 75, and the variation of Fetotal is the same as An, which determine normal crystallization state with temperature equilibrium. The chemistry of zoned plagioclase with oscillating zoning are analyzed from rim to rim, which is the minimum and maximum of An in microquartz-diorite is An36. 58 to An60. 94 and in tonalite is An41. 92 to An54. 12 respectively. The rim-to-rim trend of An and Fe, Mg, and Ti elements in the zoned plagioclase shown oscillatory zoning which indicate that crystallization process of fractional crystallization accompanied by the recharges of mafic magma in the state temperature equilibrium. The recharges of mafic magma in the center of intrusive are higher than the margin.

Tabriz Basin has had extensive Cenozoic and Quaternary volcanic activity and lies in NW Iran within the collision zone of the Arabian and Eurasian plates. Formations in the region consist of siliciclastic rocks of the Miocene age (Upper red formation), along with younger dacite volcanic rocks. The Bahlul Daghi volcanic dome in the south of Spiran is variable in terms of the composition between dacite to rhyolite. It usually contains porphyry texture with phenocrysts of quartz, plagioclase, sanidine, hornblende and biotite. Field observations clearly show that they penetrate into the sequence of the Upper Red Formation, so they are younger than these units. In order to determine the exact age of volcanic rocks, Ar-Ar age dating was performed on seven biotite crystals isolated from the dacite sample. This analysis yielded saddle-shaped age spectra with initially old apparent ages followed by decreasing to a well defined plateau age, from which a precise age for volcanic rocks can be determined. Our new 40Ar/39Ar isochron results date this volcanic rocks 2. 05± 0. 15 Ma.

Mollataleb area is located in the north of Aligudarz city, in the Sanandaj-Sirjan metamorphic zone. The regional metamorphic rocks with Upper Triassic-Jurassic age and various granitoid units are the most important geological event that occurred in the area. The development of granitoid masses in Aligudarz area aged Middle Jurassic that intruded into schists. Microprobe analyses of tourmalines in pegmatites, aplite-pegmatites tourmline vein, tourmaline nodules and quartz tourmaline veins show that these tourmalines are schorl-foitite type with dominance of schorl type. Different tourmaline occurrences in the granite units, euhedral forms and eminent chemical zoning, high Fe/Fe+Mg, deficiency in X sites and high Al contents are recognizable in most tourmalines and display their magmatic origin. Therefore, the tourmalines in Mollataleb area depended on granite environment and were formed by hydrothermal source of magma.

The granitic gneisses of Abadchi village is located in the North of Zayandeh-Rud dam, where the area is a part of Sanandaj-Sirjan Zone. The mineralogical composition of the rocks is composed of quartz, plagioclase, K-feldspar, biotite, amphibole, muscovite, zircon, titanite and allanite. Quartz crystals, as the most abundant mineral constituents of these rocks, display the different conditions of deformation dynamic on the studied rocks according to their texture. Moreover, quartz crystals show evidence of bulging recrystallization (BLG), sub grain rotation (SGR) and grain boundary migration (GBM). The deformation of quartz crystals depends on the temperature and strain-rate that by using T/strain-rate diagram can determine the deformation conditions. Therefore, the fractal dimension at quartz grain boundary is between 1. 23 and 1. 11 and temperatures between 250-400 ° C and 500-750 ° C in the granitic gneisses. Using fractal dimension and calculation of temperature, the strain rates are measured 10-11. 6 to 10-6. 6for the four domain of granitic gneiss sample. The results obtained from the diagram are consistent with the deformation evidence of quartz crystals (GBM, SGR, BLG).

In the Kurdistan Province (west of Iran), manganese mineralization has occurred in several locations including Shahini (south west of Sanandaj), Sianaw (west of Mariwan), Tawakalan (west of Diwandareh) and Golchidar (east of Marivan), but Tawakalan mineralization has characteristics which cannot be interpreted by Petrological principles. This mineralization is located at the end of northwest of Sanandaj-Sirjan zone and is located in Paleozoic formations. In this mine, ore deposits is a paragenesis of high temperature silicates like spessartite and rhodonite sometimes accompanied by tephroite that usually crystalize at high temperature and occur in absence of water; while ore deposits of Tawakalan appear as lens-shaped segments, intercalated within the shale, sandstone, volcanic tufts and radiolarites untouched by temperature and where no intrusive bodies are seen in the region. The order of crystallization of these minerals in ore deposits is: 1-spessartite and rhodonite, 2-bementite, 3-Hydreous silicates of manganese, 4-rhodochrosite, 5-manganese oxides. hydreous silicates of manganese include orientite, caryopilite, zussmanite, and manganese oxides is pyrolusite and Rancieite. Gangue is composed of quartz (mostly in form of Jaspe), minor amount of magnetite and antigorite. The carbonate and manganese oxides are secondary products of metasomatism of manganese silicates. Field studies, laboratory experiments and comparison of manganese of the Tawakalan mine with other locations in the world, suggest a two phase formation process of high temperature paragenesis as follows: in the first phase, the sedimentary manganese oxides are formed in the volcano-sedimentary layers and in the second phase, after a period of orogenese, metamorphism and plutonism, high temperature fluids released from solidification of profound plutonic body dissolve manganese oxides of the first phase and cause recrystallization of manganese in shallow levels as high temperature silicates. Metasomatism of silicates and production of carbonate and Mn oxides occur at the end of the second phase when the fluids cool down.

The Sibzar Formation (Middle Devonian) is located about 30 km east of Neyshabur and is composed of lower dolostone with intercalations of sandstone, middle basaltic sill and upper dolostone to limy dolostone, with a thickness of 334 m. Based on the crystal size in this formation, three different types of dolomite (D1, D2, Vd) were identified and according to the textural classification of the dolomite, most of the dolomite are nonplanar-a (xenotopic mosaic), planar-s (hypidiotopic mosaic) and planar-e (idiotopic mosaic), respectively. The dolomite of Sibzar Formation have an average of 21. 36% Ca, 10. 9% Mg, in terms of the concentration of the major elements. The high concentrations of Fe (average 1835. 48 ppm) and Mn (average 1824. 62 ppm) indicate the reduction conditions during deep burial. The concentration of Na (average 1108 67/1 ppm) indicates the entry of hypersaline fluids into the environment. The average concentration of strontium is 455. 41 ppm. The source of magnesium ions is Mg-rich sea waters, connate sea waters and migration of hydrothermal fluids. According to petrographic and geochemical evidence, D1-type dolomite have been formed in tidal environment, D2-type dolomites due to the aggrading neomorphism of D1-type dolomite and Vd-type dolomites are formed during diagenetic processes.

The synthesized zeolites of EU-1 and mordenite were modified via dealumination process with Nitric acid and changes of their properties including surface area, diameter, pore volume and Si/Al ratio were investigated. The catalytic performance of these two zeolites was tested and compared together in xylene isomerization process at a fixed bed reactor. The results showed that due to modification of catalysts with acid, because of the removal of a large number of aluminum atoms from the zeolite network, the Si/Al ratio and surface area of zeolites were increased, which resulted in their activity and selectivity of xylene isomerization process. As expected, the modified zeolites had much higher para xylene/ortho xylene, para xylene/xylene and m-xylene conversion than before in xylene isomerization process.

A new supramolecular compound of adeninium bis(pyridine-2, 6-dicarboxylate) Chromate(III) pyridine-2, 6-dicarboxylic acid tetrahydrate (AdH+)[Cr(pydc)2](H2pydc). 4H2O (1) (where Ad and H2pydc are adenine and pyridine-2, 6-dicarboxylic acid, respectively) was synthesized via proton transfer method and its structure was determined using single crystal X-ray diffraction technique. This compound crystallizes in the orthorhombic crystal system with Pbca space group and the unit cell parameters are a = 14. 180(14), b = 13. 036(12), c = 33. 98(3) Å and α = β = γ = 90˚ . The final R value is 0. 053 for 2523 independent reflections. The asymmetric unit of compound 1 contains anionic, cationic and neutral species. The anionic part is a complex of Cr(III) with two coordinated pyridine-2, 6-dicarboxylate groups and the cationic part is a protonated adenine. The neutral part has one molecule of pyridine-2, 6-dicarboxylic acid and four hydration water molecules. The Cr(III) atom in compound 1 adopts a distorted octahedral coordination geometry. All six coordination sites have been occupied by two deprotonated pyridine-2, 6-dicarboxylate ligands. Non-covalent and intermolecular interactions i. e. Hydrogen bonds and C = O… π interactions are responsible for the self-assembled and regular structure of 1.

In the present investigation, manganese ferrite nanoparticles substituted by cadmium with Mn1-xCdxFe2O4 composition and substituted amount x=(0, 0. 1, 0. 3, 0. 5) were prepared by Sol-gel method. Pattern analysis of X-ray diffraction (XRD) confirmed ferrite single phase structure in all samples. The average crystal size was estimated from 17 to 22 nm. The chemical bonds and ferrite formation phase of samples were analyzed by Far-FTIR and FT-IR analyses. The prepared magnetic properties of nanoparticles were analyzed by Vibrating Sample Magnetometer (VSM) which shows that saturation magnetization changes by substitution of Cd2+ in manganese ferrite. These changes are formed by cation distribution among tetrahedral and octahedral sites and superexchange interaction decrease.

In this research, molybdenum oxide (α-MoO3) thin films were coated on glass substrates using spray pyrolysis technique. 0. 05 M ammonium heptamolybdate tetrahydrate was used as precursor and deionized water as solvent. The effects of carrier gas pressure, during the spraying of the solution, on the structural, optical, morphological and gas sensing properties of thin films were studied. X-ray diffraction (XRD) pattern analysis showed preferred growth at (020) peak direction and the formation of alpha phase of molybdenum oxide. The most intensive peaks were observed in the XRD pattern of the sample prepared under the carrier gas pressure of 2 bar, which indicates better crystallization of the sample. In addition, Raman spectrum of this sample confirmed the XRD results. UV-Vis spectroscopy results showed that the sample prepared under the carrier gas pressure of 1. 8 bar has the highest optical absorption and the lowest band gap (~ 3. 48 eV). Scanning electron microscope (SEM) images showed the layer structure of samples. Moreover, gas sensor devices based on the prepared samples at different carrier gas pressures, were fabricated and their sensing performances were investigated. Results showed that, the work temperature (i. e. the lowest temperature with the highest gas response at the specified ethanol vapor concentration of 200 ppm) was 200 º C and belongs to the sample prepared under the carrier gas pressure of 1. 8 bar. Also, studying the effect of ethanol vapor concentration extent for this sample showed the increasing of sensitivity percent from 1. 42 to 15. 62 % for 100 to 1000 ppm ethanol vapor, respectively.

In this research, ZnO thin films with Al impurity as dopant were coated onto cleaned glass substrates by the spray pyrolysis technique. Crystal structure of the thin films was studied via XRD, and UV-vis spectroscopy was carried out to investigate their optical properties. Finally, in order to study the effect of Al impurity in ZnO thin films, the band structures of both pure and doped systems were calculated and compared using ab initio calculations in the frame work of DFT. The results show that polycrystalline thin films with hexagonal wurtzite structure have been grown, and the crystal size of the (002) ones is 25. 41 nm. Moreover, the transmission in the visible region is more than 80%. Furthermore, Fermi energy is shifted into the conduction band in the case of Al doped ZnO which leads to increasing the electrical conductivity and changing the optical transmission threshold.

In this study, for the first time, cobalt base ribbons were made by adding two different amounts of tungsten with Co67. 7Fe4W0. 8Si16. 5B11 and Co66. 5Fe4W2 Si16. 5B11 compounds by melt spinning in the water. The pattern of X-ray diffraction taken from these ribbons shows that these magnetic ribbons are amorphous. By using thermal analysis curves, taken from the ribbons, crystallization temperature, enthalpy, and specific heat capacity were calculated and compared. The magnetic properties of the ribbons, the Curie temperature and magnetostriction, and the hardness of the ribbons were measured by microscopic testing. The results indicate that the ribbons are soft ferromagnetic. The magnetic properties of the ribbons have been investigated by annealing the ribbons at a temperature higher than the crystalline temperature. The diffraction pattern taken from these ribbons shows that the ribbons aren’ t amorphous and crystallized from annealed in a temperature above the crystalline temperature. Due to crystallinity, the magnetic anisotropy appeared in the specimen and changed the properties of the ribbons from soft ferromagnetism to hard ferromagnetism. These results are justified by the magnetic moment and the atomic radius of cobalt and tungsten.