مجله بلور شناسی و کانی شناسی ایران
سال بیست و هشتم شماره 2 (پیاپی 80، تابستان 1399)

The alkaline extrusive rocks of Neogene from Nehbandan-Assagie region, eastern Iran, include basanite, hawaiite, mugearite and benmoreite. Relatively low Ni and Cr contents and Mg-numbers of basanites are indicative of olivine and clinopyroxene fractionation from their relevant primary magma. Decreasing of CaO, TiO2, FeOt, HREEs and MREEs with increasing SiO2 indicate fractional crystallization of amphibole, clinopyroxene and Fe-Ti oxides. In basanites, hawaiites and mugearites with less than 52 wt.% of SiO2, high Nb/U ratio and lack of Nb and Ta negative anomalies are evidence for the low effect of crustal assimilation, if any, to the chemical composition of these rocks. In more-fractionated rocks, like some mugearites and benmoreites, crustal contamination is inferred from chemical characteristics and existence of quartz xenocrysts. The trace element concentrations and ratios of these rocks are similar to those of alkaline oceanic island basalts (OIB). (Tb/Yb)N more than 1.80 and (Dy/Yb)N more than 1.60 of these rocks are considered here as their generation after partial melting of an asthenospheric mantle in the garnet stability field. In addition, geochemical differences between the basanites and the other rocks are due to formation of their magmas, respectively, after 5-7 percent and 2 percent partial melting of a garnet lherzolite source.

Intrusion of granodioritic and quartz-dioritic igneous bodies of the Oligocene age into andesitic rocks with the Eocene age resulted in occurrence of widespread argillic alteration zone in the Asbkhan area of Heris (East Azerbaijan Province, NW Iran). A significant portion of this system formed the argillic alteration zone. Based on mineralogical examinations, kaolinite, quartz, smectite, alunite, muscovite-illite, hematite, pyrophyllite, rutile, chlorite, stilbite, and calcite are the most abundant mineral phases in this argillic alteration. The distribution pattern of REEs normalized to chondrite shows differentiation and strong enrichment of LREEs relative to HREEs as well as occurrence of negative Eu anomalies during argillization support this interpretation. Combination of the obtained results from mineralogical studies, calculations of mass changes of lanthanides, and investigation of different geochemical parameters indicate that distribution and mobilization of REEs during development of the argillic alteration zone is a function of factors such as pH, temperature, stability degree of complexing ligands, adsorption, and scavenging by iron oxides. The correlation coefficients between elements reveal that clay minerals, hematite, rutile, and secondary phosphates are host of lanthanides in this ateration zone. Field evidence (the presence of silicic cap in the upper part of the argillic alteration zone along with local brecciation), mineral assemblage (alunite and pyrophyllite) and geochemical characteristics (differentiation and enrichment of LREEs relative to HREEs) indicate that hypogene processes relative to supergene processes have played very important and vital role in development and evlution of argillic alteration zone in the Asbkhan area.

The purpose of this study is to explore the influence of whole rock chemistry of metamorphic protolith on the crystal size distribution curve of garnet in metapelites. With this aim, perfect mosaical photograph from two groups of metapelites have been prepared: regional (Shahindezh schists) and contact (Dorbeh Oshnavieh aureole) metamorphic rocks image processed and their patterns illustrated. They show that the nuclei numbers in the hornfelses are one fourth of schists, but when they start to grow, it is more than 40 times. These content in addition to high degree of overstepping during regional poly-phase metamorphism, show the important role of effective water fluid presence at the contact aureole and inhibitor role of it at nucleation which help ion transportation on the nucleation sites. Considering the similar composition of garnet in two groups (almanden), it is the symptom of suitable whole rock composition of hornfelses per schists to garnet grew.

Fathabad area is located in northwest of the city of Zarand (Kerman province) in the Posht-e-Badam block of the central Iran structural zone. The Ordovician–Silurian gabbroic stocks have intruded into volcanic-sedimentary rocks of the Rizu series. The gabbros are mainly composed of clinopyroxene, kaersutite, plagioclase and biotite. Electron microprobe analyses demonstrate that the clinopyroxenes are aluminous diopside with alkaline-to-peralkaline affinity. Thermobarometry studies reveal a temperature ranging between 1121°C to 1184°C for the formation of clinopyroxene, in which the pressure varies from 6 to 11 kb. The chemical composition of clinopyroxene grains exhibit their association with oceanic island basalts that are related to intraplate rift environments. It seems that the Fathabad alkalic gabbroic stocks are related to the Ordovician–Silurian Paleo-Tethys rifting events that were emplaced during the back-arc extension in the northern margin of the Gondwana supercontinent.

The Bolboli2 copper ore deposit is located about 110 km southwest of Kerman and lies in the Dehaj-Sarduieh metallogenic belt (Kerman Cenozoic Mamatic Arc, KCMA). This ore deposit is hosted by the Eocene extrusive igneous rocks (tuff, agglomerate, andesite, and dacite) and the Oligo-Miocene intrusive igneous body (granodiorite). These rocks are host the propylitic, phyllic, and silicic alteration zones (product of the mineralization fluids). Hypogene mineralization was dominant and occurs mainly as stockwork vein-veinlets and disseminate (chalcopyrite, pyrite, and magnetite). This mineralization is overprinted by supergene assemblages such as hematite, goethite, malachite, and azurite at superficial part of ore deposit. The hypogene minerals show generally vein-veinlet, stockwork, brecciated, granular, and crustiform textures. Microthermometric studies in quartz crystals cogenetic with the ore minerals reveal 4 types (1) L-V, (2) L-V-S, (3) V-L, and (4) V fluid inclusion. Study of fluid inclusions display a Th range of 190-427ºC. The L-V-S fluid inclusions were homogenized with halite disappearance with the Ts(NaCl) ranging from  213ºC to 425ºC which corresponds with salinities within the range of 32-50 wt% NaCl equivalent. The liquid-rich 2-phase inclusions (L-V) show salinities within the range of 0.6-10 wt% NaCl equivalent. Based on microthermometric data, boiling, mixing, and simple cooling of the ore-bearing fluids were the essential mechanisms in deposition and evolution of this ore deposit. The ore-forming fluids were probably of magmatic and mixed magmatic-meteoric sources. The geological setting, structural and textural aspects, alteration and mineralization of mineral assemblages, as well as microthermometric data show that the Bolboli2 ores can be categorized as porphyry copper-type ore deposit.

Metapelites of the Do Chah complex (SE Shahrood) are composed of micaschist, garnet micaschist, chloritoid schist and garnet-bearing gneiss. In the highest degree of metamorphism, metapelites have been affected by partial melting, resulting as granitization. A significant part of these rocks, imposed by compressional tectonic regime and show typical evidence of plastic deformation and intensive mylonitization. Secondary chlorite and phengite in metapelites are indicators of retrograde metamorphism which occurred during uplifting and P-T condition of greenschist facies. Thermobarometry of these rocks shows the occurrence of a Barrovian type progressive metamorphism in relation to Cadomian orogeny (Late Neoproterozoic) in P-T conditions of greenschist to upper amphibolite facies.

This research was carried out to study hydrothermal synthesis of merlinoite and gismondine zeolites from perlite, as the raw material for the production of essential silica and aluminum, under alkaline condition, at a constant temperature of 150˚C during 3 days. All experiments were performed on the same sample of perlite powder without any purification and all reactions were carried out into the teflon hydrothermal autoclaves. The phase compositions of resultant products were analyized by X-ray diffractometer (XRD) and their morphology were examined by scanning electron microscope (SEM). According to experimental data, at a concentration of 0.25 mol/liter LiOH, only synthetic merlinoite crystallized, at the first phase. By increasing LiOH concentration to 0.5 mol/liter, gismondine was formed along with merlinoite, and then with more increasing LiOH concentration to 3 mol/liter, the production rate of gismondine has been overcome to the production rate of merlinoite.

Diabase dikes in the West Aghda  (Yazd Province) are located within the Bahramtaj mine in the Central Iran zone. These dikes are dark gray and crops out in the limestone-dolomite rocks. They are located along the east-west faults of the West Aghda. Plagioclase, biotite, amphibole, and pyroxene are the main minerals in these dikes. Plagioclases are andesine, biotite are often iron type (FeO: 24.27-31.57), amphiboles are magnesio-hornblende, and pyroxenes are Augite (En 0.50-0.58, Fs 0.14-0.22, Wo 0.25-0.31). The temperature and pressure of crystallization of these dikes have been investigated with different methods of biotite, amphibole and clinopyroxene thermobarometry. The maximum crystallization temperature is about 1150 °C and pressure less than 5 kbar. The nature of the magma for these dikes is alkaline, and oxygen fugacity is high during the crystallization. The tectonic setting of the dikes in the West Aghda is in WPT.

This study focuses on the amount and concentration of trace elements and REEs pattern in garnet crystals which experienced regional metamorphism in the central Iran micro-continent, including the areas of Deh-Salm, Zaman Abad, Mishdowan, and Tanbour. Generally, garnet crystals are isolated from mica schists of greenschist to amphibolite facies. Mineralogical composition of garnets shows almandine rich in Mg and Mn. The REE pattern of garnets can be classified in two manners, one rich in HREE, and the other rich in LREE. The concentration and modification of the REEs of these minerals indicate the protolith enrichment and substitution of Y+HREE and HFSE with bivalent cations in their crystalline structure. Influx of concentrated trace elements and LREE fluids accounts for the enrichment of LREE and LILE in the second type, and it is the function of partition coefficients ratio between the minerals in equilibrium, crystallization and/or reaction with garnet crystal.

The exposed volcanic rocks in south west of the Khoy area consist of basalts with minor amounts of plagioclase-phyric basalts. These rocks are composed of clinopyroxene plus plagioclase and plagioclase phenocrysts, respectively. The basaltic rocks are highly altered and contains high amounts of secondary minerals mainly chlorite and epidote. According to mineral chemistry, the composition of clinopyroxenes varies from diopside to augite. The clinopyroxenes are characterized by normal zoning and were formed from a primitive subalkaline magma. The studied clinopyroxenes were crystalized at pressure of 2 to 5 kbars, temperature ranging from 1100- 1150 °C and high oxygen fugacity. On the tectonic setting discrimination diagrams, the south west of Khoy basalts plot mainly in the areas of overlap between IAT, BABA and MORB. The comparison between studied basalts and basaltic rocks in the Khoy ophiolitic complex reveal that the south west of Khoy basalts might have been formed in back- arc basin settings.

West and south west of Razan igneous rocks are located in the Hamedan Province in the Sanandaj- Sirjan zone, west Iran. According to petrography and chemical studies, these rock bodies are composed of diorite, gabbrodiorite, monzonite, quartz- monzonite, andesite and andesibasalt. The results of geochemical analysis show that these rocks belong to a cal- alkaline magma series. The geochemical charactersistics of the rocks in this area have been affected by the magmatic processes such as fractional crystallization, assimilation, rate of partial melting and composition of original rock. Patterns of trace and  rare earth elements normalized to Chondrite and primitive mantle show that LREE contents are sharply higher than HREE. The magma of the intermediate-basic igneous rocks in the west and southwest of Razan have formed in a subducthon zone and volcanic arc active continental margin.

The Grouh area is located about 19 km north-east of Sarduyeh city in Kerman Province. The major lithological units in this area include Eocene andesite and andesitic basalt. Oligo-Miocene intrusive units include diorite, quartz diorite and granodiorite; while pyroclastic units include tuff and breccia. The alteration in the Grouh area is remarkable due to the penetration of the intrusive masses into the volcanic rocks. Propylitic, phyllic and  potassic alteration in the northern and southern parts of the range is widely spread. Copper ore deposits (chalcopyrite and malachite) are found in small outcrops in the microporous porphyry granodiorite in the northeastern region. Mineralization can be seen only in hypogen part, and evidence of supergene zone is very weak.. The presence of potassic alteration at the surface as well as the rough topography of the area indicates a high upsurge and severe erosion in the studied area, which possibly led to the transfer of copper to the downstream areas.

The Kuhkamar shale with a thickness of 354 m is composed of siliciclastic rocks (sandstone and shale). Petrography studies of the sandstones in this area show two petrofacies including arkose and sub-arkose. These sandstones composed of sub rounded to moderately sorted; therefore, compositionaly to texturaly, they are immature to submature with mono and polycrystalline quartz and k-feldespar. In terms of petrography, the shales are rich in quartz, albite, calcite and, to a lesser degree, clay minerals (illite and chlorite). Moreover, SEM images represent clay minerals of illite and chlorite in these shales. In order to interpret provenance, the shales of the studied section have been geochemically analyzed. These shales are rich in quartz, albite, and calcite with small amounts of clay minerals (illite and chlorite). With respect to (UCC), these shales show depletion in SiO2، Al2O3، Na2O, P2O5, Ba, Cu, Nb and Sr and enrichment in U and CaO. Plotting Al2O3 versus TiO2 as well as ternary diagrams, (SiO2/20), (K2O+Na2O), (MgO+TiO2+FeO) and Al2O3, (CaO + Na2O + K2O), (FeO + MgO), suggest that the original source of these shale was from intermediate igneous rocks. Calculated PIA and CIA indicate low to medium chemical weathering and arid to semi-arid climatic conditions in the source area. Prepared discrimation diagram using the major oxides (SiO2 versus K2O/Na2O) and ternary diagram (Na2O+ K2O), (TiO2+ MgO+ Fe2O3), (SiO2/20), shows that most of these shales were plotted in active continental margin. Paleogeographic reconstruction in this area, during the Eocene, shows that sedimentation in this area is mainly taken place in the intracontinental subsiding basin.

Remote sensing has found a special technique and effective in the geological studies and mineral identification for the determination of minerals in the primary detection. The purpose of this study is to recognize the high purity calcite mineral regions in carbonate units using Aster and sentinel 2 images. Sampling of rocks and laboratory analysis using XRF and XRD for verification. The results showed that 97.22% the purity of calcite mineral (CaCO3) is recognized in carbonate unit. The Sentinel 2 auxiliary data improved the spatial resolution of Aster visible and infrared shortwave bands to 10m. As well as CR, MF and SAM algorithms were calculated beside the calcite spectral index (CI) and RGB:831 image for calcite mineralization. By comparing the results of the algorithms, MF image had resembled to calcite spectral index image, so it was used in SAM method and calcite classification map was calculated. The results of comparing showed that calcite minerals categorized in the SAM method with the calcite index, 83.66% of calcite areas was correctly assigned to this mineral. Therefore, using spectral indexes and classification methods, minerals can be identified with the lowest cost and acceptable accuracy.

The Chah Andoo plain is located about 100 km SW Damqan in Semnan Province. Basalt, andesite-basalt, tuff and metamorphic rocks are the main rocks which exposed in the study area. Agate, jasper and agate–jasper are silica minerals widespread at the plain surface as crushed fragments from a few millimeters to 0.5 meter in dimension. Banded (mono centric), stalactite (landscape), mossy and thunder egg agates are the most frequent agate types in the area. Jaspers can be observed as banded, mossy, massive and different color types. Low quartz and moganite as the main silica polymorph minerals with impurities such as hematite, carbonate, chlorite and carbonaceous organic material were determined by micro Raman spectroscopy. Moganite is identified in the silica mineralization for the first time in the study area.

The plutonic body of Bostanabad-Meyaneh belt formed during the Cenozoic magmatism on the weast Alborz-Azarbaijan zone. The Oligocene plutonic rocks consist of alkaligranite, granodiorite and biotitegranite, intruded into the Eocene volcanic-sedimentary rocks. The predominant textures are granular, graphic and perthite. Geochemical evidence reveals that they are cogenetic and have features typical of calk-alkaline to high-K calk-alkaline, metaluminous with I-type nature. Enrichment in LILE (i.e. Cs, K, Rb and Th) rather than HFSE (Eg., Nb, Zr and Ti), typical negative anomalies of Nb and Ti and LREE enrichment in comparison to HREE, are important characteristics indicating that these rocks were formed in a magmatic belt in a subduction zone. Positive anomalies of Pb and K demonstrate the involvement of continental crust in evolution of parental magma. During magma ascent, assimilation processes, fractional crystallization and crustal contamination (AFC) took place simultaneously. Tectonic discrimination diagrams show formation of these rocks in VAG, Syn-COLG event and an mature continental arc setting with less than 45 Km crustal thickness. Primitive magmas should have formed by low degree melting of an enriched mantle wedge peridotite.

The hosted-rocks of the Pb-Zn ore deposits in two mines of Karavangah and Dehno (north of Kuhbanan) contain carbonate rocks of the Shotori Formation (Middle Triassic).The identified carbonate facies consists of limestone and dolomite, but ore bodies mainly occurred in dolomite facies. Petrographic studies show that the dolomites can be divided into four classes including fine crystalline, medium crystalline, coarse crystalline and saddle dolomites. Geochemical data (major and trace elements) of dolomites have almost similar characteristics and show a noticeable enrichment of lead and zinc. Also, significant enrichment and similar trend are observed in the REE of hosted-rock samples. Therefore, due to similarity between geochemical characteristics of the hosted-rocks, it seems that magnesium source for dolomitization was mainly seawater, but the influence of ore fluids is significant on the formation of coarse crystalline dolomites.

This study have been developed BiFeO3/reduced graphene oxide (BFO/RGO) nanocomposites by introduction of RGO in the structure of BFO nanoparticles in a short term ultrasonic treatment. The X-ray diffraction pattern and Fourier-transform infrared spectroscopy analysis reveal that the BFO/RGO composites were successfully synthesized. UV-visible absorption show that the introduction of RGO can effectively reduce the recombination of photo-generated electron and hole pairs and the lower band gap energies were also identified for BFO/RGO composites as compared to 1.97 eV for BFO. The photocatalytic performance of BFO/RGO nanocomposites is stable and exhibit considerably higher photocatalytic ability over the pristine BFO for the degradation of methyl orange solution under visible light irradiation. The possible mechanism behind the superior photocatalytic performance of BFO/RGO nanocomposite has been critically discussed.