مجله بلور شناسی و کانی شناسی ایران
سال بیست و سوم شماره 2 (پیاپی 60، تابستان 1394)

Keybarkuh is located about 70 Km southwest of Khaf city (Khorasan Razavi Province) in the northeast of the Lut block. Rock units in the area comprises of slate, phyllite, schist and recrystalized limestone with Paleozoic age that was intruded by granite to diorite as dikes and stocks of Cretaceous to Tertiary age. Based on magnetic susceptibility, intrusive bodies are oxidant and reducing which the oxidant bodies mostly having alteration and mineralization. The eastern Keybarkuh oxidant bodies are of Midlle Eocen, related to subduction environment of continental margin, often high-K to shoshonitic and metaluminous. Propylitic alteration zones with broader area and sericitic, argillic and silicic with less distribution were observed in the southern area. Mineralization is seen in the contact of intrusive bodies or in joint and fractures of them as veins and veinlets in south of the area. Veins and veinlets with northwest to southeast strike, 70 to 80 degrees dip to the northeast have thickness upto half meter. They can be divided into two sets: 1-Veins and veinlets associated with galena, sphalerite and barite as primary minerals, which formed the first generation of mineralization. 2- Veins and veinlets associated with pyrite, chalcopyrite and quartz as primary minerals; covellite, bornite, chalcocite, malachite, azurite and iron oxides (magnetite, hematite and limonite) as secondary minerals which is the second generation of mineralization. Paragenetic sequences of minerals and relationship between minerals are indicative of a hydrothermal activity and deposition of the above mentioned minerals in at least two stages in the upper part of oxidant intrusive bodies. Geochemical exploration of stream sediment show anomalous Cu (68 ppm), lead (1691 ppm), zinc (320 ppm), barium (5003 ppm) and the rock also show anomalous Cu (3%), gold (2657 ppb), silver (ppm 160), lead (4%), zinc (2159 ppm), barium (1466 ppm) bismuth (1767 ppm) and Mo (66 ppm) in the southern parts of the area which are relatively high.

The study area is a part of Sanandaj- Sirjan Zone that is located in the northeastern of the dimension stone of Jan mine in north of Doroud city on Lorestan Province. It is mainly composed of deformed metamorphic rocks including deformed marbles associated with mylonitic gneiss- granite and amphibolite. The main texture of the marbles is lepidogranoblastic and their mineralogical composition are calcite, quartz, phengitic muscovite, epidote, sphene, opaque minerals and minor plagioclase. Calcite grains have preferred orientation, which show strain and crystal-plastic deformation. The formation of flayser texture in the quartz lenses, undulatory extinction in the quartz grains, existence of pining microstructures, dynamic recrystallization as grains boundary migration (GBM) between calcite and quartz, bulging recrystallization (BLG) in the quartz grain boundaries along fracture planes, Subgrain Rotation (SGR) and also, deformation twinning in calcite crystals show the temperature of deformation ranges from 150 to 300 °C for the marbles.

The Kuh-Sorbi barite-Pb ± Cu deposit, which is located southeast of Mashhad in Khorasan Razavi Province of Iran, occurs as vein, open space filling, host rock replacement, and cement within the fault breccia in the Upper Triassic Nayband Formation metamorphosed carbonate rock unit. This deposit contains of barite (80–85%) and galena (10–15%), with small amounts of chalcopyrite and quartz. Barite is marked by very low concentrations of Sr (2.5–3%) and belongs to the barite end-member of the barite-celestite solid solution series. Hydrothermal alteration, such as silicification and dolomitization, provided appropriate physical and chemical conditions that permitted the passage of ore-bearing fluids and participated in precipitation and ore localization. Carbonate-hosted ore contains ~1% Pb, ~0.15% Cu, and maximum 288 ppm Sb, whereas Ag (< 40 ppm) and Bi (<10 ppm) is very low. In addition, concentrations of Ag, Bi, and Sb in separated galena samples ranged from 12 to 175 ppm, 43 to 101 ppm, and 137 to 270 ppm, respectively. The ratios of Sb/Bi in galena from the Kuh-Sorbi deposit range from 2.25 to 5.63 indicate medium-temperature galena, which formed at medium pressure. The galena samples are Sb-rich. Microthermometric analyses in two-phases (liquid and vapour) fluid inclusions suggest that barite and ore minerals were precipitated by a medium-temperature (250 to 386ºC) low-saline (4.9 to 1.8 wt. % NaCl equivalent) solution originated possibly from a metamorphic fluid. Temperature decreasing may have played an important role during barite–Pb ± Cu mineralization. Based on geology, mineralogy, texture and fluid characteristics, the Kuh-Sorbi deposit is classified as a mesothermal-type deposit.

Composition of the Kiyamaki dome has mostly dacite and granodiorite in rims, with SiO2 contents ranging from 64 to 73 wt% and Mg# values ranging from 27 to 57. These rocks are high-Si adakite. Geochemical characteristics and Sr and Nd isotopic rates indicate that the rocks of Kiyamaki dome are a post-collisional adakite. Combined geochemical and Sr–Nd isotope data suggest that the Kiyamaki adakitic magma derived from partial melting of mafic rocks in the lower part of a thickened crust. So, with attention to tectonic setting and source of derived adakitic magma, age of Eocene to Miocene for generation and closing time of Neo-Tethys (Middle Miocene), it is not possible that generation of Kiyamaki adakites be directly related to geodynamical evolution of Neo-Tethys. Here, with suppose of age information for generation of Kiyamaki dome and closing of Neo-Tethys,formation of domes in the northern part of Tabriz fault can be related to the collision of Sanandaj-Sirjan micro-continual with Alborz-Azarbaijan block in Paleogene that was happened due to subduction of oceanic crust of Khoy-Zanjan basin toward beneath of Alborz-Azarbaijan block.

Soltan Maidan Basaltic Complex consists of a thick succession of basaltic lavas associated with some thin sedimentary interlayers that are exposed in the northwest to northeast of Shahrood. Soltan Maidan basaltic rocks has been generated from magma with transitional to mildly alkaline nature and derived by 14-20 percent partial melting of an enriched garnet peridotitic mantle source in an intra-continental rift setting during Late Ordovician to early Late Silurian. These basaltic rocks are relatively uniform in mineralogical composition and they have undergone moderate to high degrees of alteration. Labradorite plagioclase and augite clinopyroxene are major minerals, and Fe-Ti oxides as titanomagnetite and ilmenite form accessory minerals in these rocks. Thermobarometry results on the clinopyroxenes indicate that they have crystallized in temperatures between about 1100oC to 1200oC, with pressures less than 6 kbar and show that they have crystallized in magma chamber/chambers located at depths less than 23 kilometers.

Surian volcano–sedimentary complex located on the eastern edge of the Sanandaj-Sirjan metamorphic zone, southwest Iran. Graphite schist is the most abundant lithological facies in this area. Due to the high grade of the graphite ore (up to 50%), the exploitation of the ore is economically valuable. Gangue minerals include quartz, muscovite, plagioclase, clinochlore, zircon and ilmenite. The occurrence of crystalline graphite with ordered structure is shown by the presence of a first order peak in Raman spectra (~1587 cm-1 Raman shift) and 3.35 ˚A d spacing. A linear relationship between metamorphic temperature and the Raman parameters R1 and R2 make graphite an accurate geothermometer. Using this geothermometer gives metamorphic Surian complex temperatures range from 234 to 258 ˚C, consistent with previous studies that give P-T conditions of green schist to lower amphibolite metamorphic facies.

In this study, Copper substituted Ni-Zn ferrite nanoparticles with compositions of Ni0.65Zn0.35CuxFe2-xO4 x= (0, 0.05, 0.1, 0.12, 0.15, 0.18, 0.2) were prepared by a polyvinyl alcohol (PVA) sol–gel process and the structural and magnetic properties of the samples were investigated by various analysis. Results obtained from X-ray diffraction (XRD) showed that the lattice parameter and the average particles size increase with the addition of copper in the mixed NiZnCu ferrite system. Increasing in grain growth attributed to the crystal surface temperature. The average crystal size is in the range 13-26 nm. According to the FT-IR results, the shifting of the ν1 band towards lower frequencies, may be attributed to the increase in the unit cell dimensions. The effect of copper concentration on saturation magnetization (Ms) and coercivity (Hc) were investigated. The saturation magnetization observed to decrease up to x≤0.1, and then increases linearly for further substitution. The variation of Hc can be explained on the basis of substution Cu2+ iones in NiZn ferrite, surface effect and the grain growth.

Nanoparticles of Ni(0.5-x)MnxZn0.5Fe2O4 with stoichiometric proportion, x = 0, 0.25, 0.35, 0.5, were prepared via the chemical co-precipitation process. The structure properties of nanoparticles were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Their magnetic properties were evaluated on a vibrating sample magnetometer (VSM). The XRD patterns showed the formation of single-phased cubic spinel structure for all the annealed samples with no minor phase in nanometer size. Moreover the lattice constant tended to increase with increasing substitution of Mn+2 ions without any change in the spinel structure. The TEM images indicated that the nanosized particles were formed after annealing. The magnetic measurements of nanoparticles were done at room temperature and the results showed that all nanoparticles exhibit a typical superparamagnetic behavior with no hysteresis. Moreover, the saturation magnetization increases up to a substitution level of x = 0.25 and then starts to decrease. The observed behavior is attributed to substitute of Mn+2 ions into the octahedral sites of the cubic spinel lattice which affected to its sublattice magnetization.

Metamorphic rocks in SW Arak composed from two groups including regional and contact metamorphism. Regional metamorphic rocks are composed of slate, phyllite and micaschists and locted in green-schist facies and contact metamorphic rocks are composed of spotted schist and hornfels respectively. Mineralogically, these rocks are composed of quartz, chlorite, muscovite, biotite and cordierite. Petrographic studies of these rocks show that cordierite mineral formed during contact metamorphism. On the basis of mineral chemistry, the Chlorite has ripidolite compositions and muscovite is rich in the muscovite end-member. Based on calculations, chlorite mineral in regional metamorphic rocks in the study area have formed at temperature of 387-416 ºC and low-to medium pressure. According to the microscopic studies, field observations and obtained analyses of samples from different protoliths, the rocks have been sedimentary and graywacke or shale type. Major and trace elements concentration (e.g. K2O, TiO2, Rb, Ni) indicates that the primary igneous rocks was acidic (andesite to rhyodacite). In comparison with average of upper continental crust, the rocks of studied area of P, Sr, Ba, Ti negative anomalies and of Rb, K positive anomalies that cause replacements of these elements during metamorphism and alteration. Discriminations diagrams of tectonic setting indicate a subduction Zone. Using major oxides elements, the continental active margins considered for metapelites source.

Metamorphic rocks in SW Arak composed from two groups including regional and contact metamorphism. Regional metamorphic rocks are composed of slate, phyllite and micaschists and locted in green-schist facies and contact metamorphic rocks are composed of spotted schist and hornfels respectively. Mineralogically, these rocks are composed of quartz, chlorite, muscovite, biotite and cordierite. Petrographic studies of these rocks show that cordierite mineral formed during contact metamorphism. On the basis of mineral chemistry, the Chlorite has ripidolite compositions and muscovite is rich in the muscovite end-member. Based on calculations, chlorite mineral in regional metamorphic rocks in the study area have formed at temperature of 387-416 ºC and low-to medium pressure. According to the microscopic studies, field observations and obtained analyses of samples from different protoliths, the rocks have been sedimentary and graywacke or shale type. Major and trace elements concentration (e.g. K2O, TiO2, Rb, Ni) indicates that the primary igneous rocks was acidic (andesite to rhyodacite). In comparison with average of upper continental crust, the rocks of studied area of P, Sr, Ba, Ti negative anomalies and of Rb, K positive anomalies that cause replacements of these elements during metamorphism and alteration. Discriminations diagrams of tectonic setting indicate a subduction Zone. Using major oxides elements, the continental active margins considered for metapelites source.

Organic acids, such as malic, citric, and oxalic, play important roles in agricultural soils. They can affect chemical and physical properties of the rhizosphere and therefore, increase cation and anion concentration in soil solution. This increases the uptake of elements by plants. A factorial experiment with a completely randomized design was conducted to investigate and compare the influence of two organic acids (oxalic and citric), two pH values (6 and 4), two concentrations (1 and 10 mM) and two sizes of mineral particles (5 and 50 micron) in different contact times (2, 6, 12, 24, 48, 72, 168 hours) on the release of Mg from sepiolite. For each experiment, a control was run. All experiments were conducted using three replications. Results revealed that the amount of Mg released from sepiolite particles in citric acid treatments was much more than those of oxalic acids. Results also illustrated that with the increase in shaking time and concentration of both organic acids and the decrease in pH value and the size of particles, the release of Mg from sepiolite mineral increased. However, it seems that among all parameters studied, the size of sepiolite particles has the least influence on the Mg release.

Ophiolites of the Zagros orogenic belt are part of the Tethys ophiolites, because of their geographical locations and link the Middle East ophiolites and other Asian ophiolites (e.g. Pakistani and Tibetan) to the Mediterranean ophiolites (e.g. Troodos, Greek and East European). The nature of the Harsin- Sahneh ophiolite (Kermanshah) traditionally identified as one of the Mesozoic southern branch of the Neo-Tethys Ocean and remnants of the Peri- Arabic ophiolite system obducted onto Arabian shield (Gondwana) that is reinvestigated in this study. Petrographic evidence indicates that this ophiolitic sequence consists of both mantle and crustal suites. In generals lithologies in this complex include harzburgitic and lherzolitic peridotites, cumulate, pegmatoidic and mylonitic gabbros, dyke complex and basaltic pillow lavas. Mineral chemisty of Harsin mafic rocks indicating island arc setting for this part of complex and geochemistry of mafic and ultramafic rocks of Sahneh region displaying P-type MORB nature. Presence of basalts with different composition in this region can be interpreted as the interaction between MORB-type and OIA-type asthenosphere. Field relationships and geochemical evidence indicate that involved ophiolites were part of a rifted basin at the ocean-continent transition zone, which formed in the south of the Neo-Tethyan Ocean. The break-off of Neo-Tethyan slab and subduction of this slab branch itself during Cretaceous led to cessation of Neo-Tethyan subduction branch Sanandaj-Sirjan block, and forming arc-back arc basin and related rocks in the Kermanshah ophiolite and MORB magmatism occurred in response to slab retreat in the Eurasian continental margin.

The granitoid intrusions of Dehnow, which is located in northwest of Mashhad in immediate contact with garnet-rich hornfels, contain large crystals of garnets. They provide an excellent opportunity to study the effect of host rocks in contamination of a garnet-bearing granitoid magma. The garnet crystals contain abundant inclusions that are indicative of igneous phases and are arranged in a circular pattern in crystal. Biotite and hornblende-rich rim around garnet crystals show that the garnets are not in equilibrium with the host magma and is replaced by ferromagnesian phases of the granite magma. Dehnow granitoids are metaluminous in nature. As normally metaluminous magmas have not enough aluminum for garnet stability, it seems that these garnets are peritectic crystals and formed as a result of heterogeneous melting of xenocrysts and xenoliths derived from host rocks.

In this research, M- type strontium hexaferrite nanoparticles (SrFe12O19) were synthesized via combustion sol–gel technique. To determine the optimum annealing temperature, thermogravimetry-differential thermal analysis (DTA/TG) was used. Based on the results obtained from this analysis, the powders strontium hexaferrite were annealed between temperatures 750 and 1050°C. The structural and morphology properties of the samples were investigated by X- ray diffraction (XRD), Fourier transform infrared spectroscopy (FT- IR) and scanning electron microscopy (SEM). The XRD results showed that the sample with annealing temperature and annealing time of AWT IMAGE 950°C and 4h is single-phase. Also, magnetic and dielectric properties of the samples were studied by VSM and LCR meter at room temperature. The results of magnetic measurements show that there is only one peak in the magnetic susceptibility of all samples. This and the results obtained by XRD patterns are correspond to that of the single phase. Also, the dielectric measurements show that the samples with increasing frequency dielectric constant and dielectric loss of the samples decrease. These decline procedure dielectrics indicative of normal behavior of ferrites. The FT-IR results revealed that the frequency bands in the range of 560–580 cm-1 and 430– 470 cm-1 correspond to the formation of tetrahedral and octahedral clusters of the metal oxides in ferrites, respectively.

Late Neoproterozoic- Early Cambrian schists exposed in southwest of Zanjan in northwest Iran. Intrusion of Tertiary Korramdaragh monzogranite body within these schists have caused crystallization of porphyroblasts of hexagonal cordierite with cyclic radial sixling twin structure. Hexagonal cordierite consists of six optically sectors. Under microscope with crossed polarized, all of the sectors are anisotropic and their optical characters such as extinction positions and optical directions are relatively symmetrical in relation to twin boundaries. This structure could be explained by considering a section perpendicular to six-fold axis of a dipyramid hexagonal crystal. In this model, surfaces with Miller indicies of AWT IMAGEhave identical optical characters. Absence of optical structure within each sectors as well as sharp boundary among twin sectors may indicate that low temperature orthorhombic cordierite is formed on the prismatic surfaces of an intial hexagonal indialite.

In this research, work nanopowders of Zn1-xMnxO (0.0AWT IMAGE) dilute magnetic semiconductor were prepared via sol-gel autocombustion method. The crystal structure and phase purity of samples were confirmed by X-ray powder diffraction (XRD) analysis. The particle sizes were found to be 5-35 nm from Transmission Electron Microscopy (TEM) and Scherer's formula. The hysteresis in the M-H behavior shows the presence of room temperature ferromagnetism in Mn doped ZnO. XPS results show that there is Mn2+ions in all Mn doped samples. Antiferromagnetic interaction between neighboring Mn-Mn ions suppressed the ferromagnetism at higher doping concentrations of Mn.