مجله بلور شناسی و کانی شناسی ایران
سال بیست و دوم شماره 4 (پیاپی 58، زمستان 1393)

More than 20 tonalitic to granodioritic plutons with Oligo-Miocene age had intruded the Eocene volcanic rocks, in south-east of Urumieh- Dokhtar magmatic belt, north-west of Shahre-Babak. These rocks show granoporphyritic texture and consist of phenocrysts of plagioclases (An21-An44), with normal to reverse zoning, magnesio hornblende and tshermakite and biotites. The matrix consists of fine-grained plagioclase and potash-feldspars, amphibole, biotite, quartz and opaque minerals. K-feldspars compositions vary between (Ab26.6-An0.07-Or73.4) to (Ab73.3-An15.8-Or11). Thermometry and barometry, based on Al content in amphibole, suggest that hornblendes are formed in 2-5.5Kb pressure (8.3 to 22 km depths) and 707-793˚C temperature. Results also imply that amphiboles formed at different depths and temperatures. Geochemical data suggest that the calc-alkaline plutons formed in an active continental margin. 

According to the olivine and spinel chemistry, two types of peridotite were identified from west north Piranshahr ophiolite. Peridotite rocks are classified based on chemistry of spinel and olivine. Average number of Cr in spinels (Cr#[(100*Cr/(Cr+Al))]) and Mg-number (Mg#[100*Mg/(Mg+Fe)]) in dunite are 0.63 and 0.51 respectively. In harzburgite, Cr# is 0.33 and Mg# is 0.67 and in spinel from serpentinite Cr# is 0.45 and Mg# is 0.55. Also in dunite, Cr/Al is 1.6, in harzburgite Cr/Al is 0.49 and in spinel from serpentinite Cr/Al is 0.81. According to chemistry of spinel and olivine, there are two types of peridotite with different tectonic setting in the Piranshahr ophiolite (which age is upper cretaceous). Discriminant diagrams indicate that dunite is supra-subduction peridotite with a forearc setting, whereas harzburgite and serpentinite are abyssal peridotite. Two different tectonic settings in peridotites of this region are comparable with the Oman ophiolite in Oman-Zagros ophiolitic belt.

There are numerous outcrops of lamprophyric rocks, as sill and dikes, in the northwestern part of Iran. These rocks can be classified in two mica- and amphibole-rich types. Amphibole-rich type includes amphibole, olivine psudomorphs, and clinopyroxene phenocrysts in the matrix of feldspar and altered glass. Mica-rich lamprophyres include mica and clinopyroxene phenocrysts in the matrix of feldspar and glass. Amphiboles represent kaersutite composition and mica crystals mainly show phlogopitic composition. Clinopyroxene crystals have mainly salite-diopside composition. Clinopyroxenes in the amphibole-rich type have higher Al2O3 content. Studied lamprophyres are formed in a high oxygen fugacity condition and their magmas have been experienced low pressure crystallization. According to nature of minerals, mica-rich lamprophyres have calc alkaline nature and are minette and amphibole –rich type represents alkaline nature and can be consider as comptonite. Mica-rich lamprophyres originated from phlogopite and/or potassic amphibole bearing metasomatized lithospheric mantle in a orogenic tectonic setting. Amphibole-rich lamprophyres probably originated from a lherzolite mantle that includes fluid-bearing minerals.

Sefidkuh Granitoid is located west of Nehbandan (South Khorasan Province) east of Lut Block. Compositionally, this granitoid ranges from granite (monzo and synogranite), to granodiorite and tonalite. It has microgranular felsic enclaves with minerals similar to the host body. Major minerals are quartz, plagioclase, microcline, orthoclase, and biotite which were analyzed using electron probe micro-analyzer (EPMA) for thermometry and mineral chemistry studies. Plagioclases in granites are mainly andesine and sometimes albite and in enclaves they are andesine. Anortite content in plagioclase decreases from core to rim, which shows normal zoning of plagioclase. Alkali feldspars in enclaves are sanidine compared to orthoclase in granite. Biotites in granite are primary ferroan and formed in low fo2 and under, reduced condition while biotites in enclaves are primery magnesian and formed in high fo2 and oxidized conditions. Thermometry based on feldspar and biotite compositions yielded about 500-750 ˚C for granite and 650-950 ˚C for enclaves. Mineral chemistry studies indicate that granite (peraluminous magma) and enclaves are derived from a calc-alkaline magma belonging to active continental margin setting.

In this work, the structural and magnetic properties of LaMn1-xCoxO3 (x = 0.00, 0.25, 0.50, 0.75, 1.00) are investigated. The structural characterization of compounds by X-ray powder diffraction is evidence for a rhombohedral structure (R -3c space group). Much less increase of the unit cell volume suggests that Co enters in lattice as Co+2 for x ≤ 0.5 while much more decrease of the unit cell volume suggests that Co enters in lattice as Co+3 for  x < 0.5. The results of magnetic measurements show strong ferromagnetic interactions Mn+4 - Co+2 in the range (0.0 < x ≤0.5) while antiferromagnetic interactions Mn+3 - Co+3 and Co+3 - Co+2 is progressively settled at higher cobalt concentrations.

This study has focused on provenance of Eslamlu metapelites, NW Iran. Whole rock chemistry analysis has revealed that these metapelites are rich in Iron and Aluminum and as a result the modal abundance of garnet (Almandine) is high. But those samples which are rich in SiO2 are poor in Al2O3, therefore, Eslamlu metapelites have less cordierite and aluminosilicates. The position of different samples in AFM compatibility diagrams is similar, as a result, bulk rock chemistry variable was constant and parageneses are produced due to changes in P and T of metamorphism. Further studies has unraveled that parent sedimentary rocks have been Fe-shale and graywacke. The high concentration of Al2O3 and Fe2O3 shows that the rocks are Laterite.  PIA, CIA and CIW indexes are high showing intense weathering conditions; hence the aluminum content is very high. According to major element composition of metapelites, tectonic environment of igneous parent of sediments, not Ruteh sediments, has been active continental margin.

A total of 50 boreholes have been drilled in the sediments of the study area in south west of Marvast. Based on heavy minerals investingation, the amount of monazite in these sediments rangs from 50 to 525 gram per tons. Analysis of monazites from Marvast and sediment samples with ICP-MS and normalization of some data with upper earth crust and chondrite showed that Marvast monazite enriched in all of REE specially LREE. The source rock of monazite is Upper Triassic black shale which is interbedded with sandstone, limestone and conglomerate. Erosion and weathering of these rocks have released monazite and enriched them in the sediments nearby. Iso-grade maps of  monazite in different depths from 1 to 6 m showed that the strongest and the most widely anomalies are at the depth 1 m, and with increasing the depth, intensity and distribation of the anomalies decreased, as the deepest anomaly has 5 meters thickness. Also, with the simple comparison, a good correlation exists between the presence of anomalies and the thickness of sediments or the depth of bed rock.

For identification and differentiation of different types of dolomites of the Padeha Formation, three stratigraphic sections in the northern and southern Tabas Block, with the maximum amount of dolomite, were selected and sampled. Based on petrographic evidence and geochemical data, three types of dolomite were identified, including primary (PD), replacement (RD) and vein and pore filling (VD) dolomites. The PD dolomites are fine-grained, anhedral with fenestral fabric and have sedimentary structures such as planar lamination, mud cracks, stromatolite and teepee structures, as well as dark and dark-red luminescence. The RD dolomite is mainly replaced the matrix and fossil fragments and observed as subhedral with orange to red luminescence. The VD dolomite is often coarse-grained and euhedral and according to the intensity of luminescence, six petrotypes were identified in this type of dolomite. The PD and RD dolomites indicate a similar range of geochemical data that reflects they formed in similar conditions. Based on oxygen isotopes, these dolomites formed at temperatures of 44 °C and 59 °C, respectively. Therefore, marine and very shallow burial model is the most probable model for the formation of PD and RD dolomites. The VD dolomite has the lightest oxygen isotope values, therefore on this basis, this type of dolomite is formed at 82 °C. Moreover, the study of fluid inclusions in these dolomites shows an average temperature of 83 ° C. The VD dolomite has likely formed in deep burial conditions and burial dolomitization model is proposed for this type of dolomite.

The Soleimanieh ultramafic-mafic cumulate rocks (East of Sabzevar) include gabbronorites, amphibole gabbronorites, pegmatite gabbros, leucogabbronorites, norites, diorites and plagioclase bearing amphibole peridotites. The Cr-number of spinels in amphibole peridotites and olivine gabbronorites varies from 0.44 to 0.45 and 0.42 to 0.44 respectively. Geochemically, the gabbroic rocks are characterized by Mg# between 50 to 65% and their composition is directly related to modal abundances of the main rock-forming minerals. They have low TiO2 content, indicating boninitic to highly depleted island-arc tholeiitic affinities for their parental melts. The rocks have flat to depleted LREE patterns (relative to HREE). Enrichment in LILE and depletion in HFSE are characteristics of the Soleimanieh gabbroic rocks, showing formation of the rocks in a supra-subduction zone environment. Compared to the gabbroic rocks, the Sabzevar lavas have calc-alkaline characteristics and seem to be formed in a subducton zone environment.

The Plio- Quaternary volcanoes are located in the NE-Qorveh (Kurdistan) in the Qorveh-Takab volcanic belt, in the Hamedan-Tabriz Zone (HTZ). The volcanic rocks consist of basalt to olivine-basalt. The electron microprobe (EMP) analyses of pyroxenes show occurrence of one type of clinopyroxene, as diopside (Fs 2.65-6.42 En 40.44-50.47 Wo45.97-53.14) with Mg # = 84-98. The compositions of the pyroxenes suggest that rocks belong to alkaline-subalkaline magmatic series.  Considering different methods of geothermometry of clinopyroxene, the temperature of  crystallization stage for pyroxene was 800-1300°C. Distribution of Al in octahedral and tetrahedral sites of pyroxenes displays that this mineral is crystallized from a magma with ˂ 10% water contents, in low-medium pressure which is in accordance with their formation the depth of 18-30 km. Fe+3 content of clinopyroxenes  implies crystallization in high oxygen fugacity condition.

Eslamlu contact aureole, which is located at northern Oshnavieh Township, contains metapelites, calcsilicates and calcite-dolomite marbles. Some Cld, Grt, Crd, and porphyroblasts together with Sil, Hc and graphite crystals are existing at the metapelites. The most significant feature of Eslamlu aureole is its index informative reaction textures of metapelites through which metamorphic reactions are extracted. Textures and paragenetic relationship of index minerals has unraveled that overstepping rate has been high. Based on petrogenetic grid drawn from Thermocalc software data, temperature of garnet-cordierite-sillimanite zone estimated at least 700 °C at the pressure of 2 kbar.

This research presents data on widespread abnormal accumulations of Trace and Rare Earth Elements in many coal deposits worldwide. There have been many studies on the distribution and geochemistry of REEs in coal. ∑REE content in most coals varies from several µg/g to several hundred µg/g, and the REEs are distributed in minerals although some are associated with organic material in coal. In this Study, 4 samples from Karmozd coal mine in Alborz region of Iran have been analysed using ICP-MS method. The Results show some Trace and Rare Earth Elements accumulation in coal basin of Iran are much higher than China, USA, most world coal and Clark value. In Karmozd coal mine, the average ∑REE and outlook index (Coutl) are 378/21 µg/g, 0/48 respectively. The enrichments origin of these elements in karmozd coal basin is clastogenic and related by leach of pyroclastic materials riched from light rare earth elements. At present usual REE deposits (Carbonatite and weathered crust elution) are being exhausted therefore, it is possible to recover REE during different stages of developing such coal deposits: overburden removal, coal mining and combustion, and after exhaustion of the solid fuel resources.

Superstructure orthorhombicII (OII) phase in polycrystalline samples of YBCOx was observed by using synchrotron in-situ high resolution powder diffraction (HRPD) techniques at 300˚C. Rietveld method (RM) refinement was employed to analyse the collected diffraction data under proper oxygen partial pressure atmospheres. Our study indicates that by oxygen uptake, the samples undergo structural phase transition from initial tetragonal phase to the superstructure OII phase with x ≈0.6. According to our previous study this transition follows 1st order Gibbs lever role. Evidence for exsistence of dominated OII superstructure in powder samples at 300 ˚C, makes a valuable correction on the YBCOx’s structural phase diagram, which has been historically controversial and also would be interesting for applications.

Single crystals of Schiff base compound 2-[(2-chloro-4-nitrophenyl) iminomethyl] phenol (1) were grown by the slow evaporation technique at room temperature. The crystal structure of the title compound was determined by single crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group P21, with two symmetry independent molecules. Intramolecular O-H···N hydrogen bonds form S(6) motifs in each molecule. Intermolecular C-H···O interactions connect the molecules into a three dimensional network.

A new thiosemicarbzone compound was prepared by the reaction of acenaphthenequinone and thiosemicarbazide (1:1 molar ratio) in absolute methanol at 70°C. The crystal structure of this compound, acenaphthenequinone thiosemicarbazone mono methanol, was determined by X-ray crystallography. The unit cell parameters are as follows: a = 7.0384(14) Ǻ, b = 14.202(3) Ǻ, c = 14.270(3) Ǻ, β = 104.26(3)°. It crystallizes in a monoclinic system, with space group P21/c and four molecules in the unit cell. The final R value is 0.0738 for 2422 independent reflection.  Both inter and intramolecular hydrogen bonds exist in crystalline system.

 The study area is located about 110 kilometers southeast of Mashhad and approximately 40 kilometers southeast of Fariman. The area is considered to be a part of the central Iran zone. It includes metamorphic rocks with different protoliths consisting of pelitic, carbonate and quartz - feldspathic rocks. The metamorphism in the study area is considered to be a contact regional metamorphism with a low pressure - high temperature grade. According to petrographic studies, the metamorphism in the region reached the upper limit of amphibolite facies.  On the basis of different mineral assemblages, three zones were recognized, including Andalusite-Cordierite, Sillimanite - Andalusite, and Sillimanite – K-Feldspar zones. Using Thermocalc software, the average temperature and pressure for the peak of metamorphism in the metapelitic rocks are 664 ºC and 2.5 Kbar respectively. Based on calculated maximum pressure (2.5 Kbar), the depth of ~7.8 Km for the metamorphism is estimated.