جستجوی مقالات مرتبط با کلیدواژه "گرمابی" در نشریات گروه "زمین شناسی"

The Mazraeh manganese deposit (southwest of Maku, north of West-Azarbaidjan Province, NW Iran) is developed in the form of scattered lenses at the contact of pillow basalts and pelagic limestones, belonging to the Khoy-Maku ophiolitic complex. Mineralogically, the ores mainly contain pyrolusite, psilomelane, manganite, and braunite which are accompanied by lesser amounts of hematite, goethite, quartz and calcite. The distribution pattern of REE normalized to chondrite along with some geochemical parameters related to lanthanides, such as La/Ce, (La/Nd)n and (Dy/Nd)n, show a hydrothermal origin for this deposit. This idea is supported by some geochemical diagrams (Co/Zn vs. Co+Ni+Cu, Zn-Ni-Co, and Mn-Fe-[(Co+Ni+Cu)]×10) and elemental ratios such as Mn/Fe, SiO2/Al2O3, U/Th, and Co/Zn. The high concentration of lanthanides in ores (on average of 767 ppm), compared to known hydrothermal manganese deposits, reveals the effects of diagenetic processes on this deposit. The occurrence of negative anomalies of Eu and Ce indicates the low-temperature hydrothermal fluids, responsible for the mineralization. The presence of detrital materials in the ores can be inferred by the concentration values of oxides like Al2O3 and TiO2.

Band-e-Cherk prospect is located in the north of Isfahan province, on the western boundary of the Central Iran zone. The rock outcrops in this area are mainly comprised of Anarak Palaeozoic-Mesozoic metamorphic complex, Lower Cretaceous sedimentary sequence, Paleocene conglomerate, and Eocene volcanic rocks. The host sequence involves two units, from bottom to top: 1) Palaeozoic-Mesozoic metamorphic complex, and 2) Lower Cretaceous succession. Mineralization is occurred as vein/veinlet, replacement, banded, breccia, banded, spotted, and microbial remains (botryoidal, radial, and needle). The main ore minerals are hematite, goethite, pyrolusite, braunite, psilomelane, and minor todorokite, cryptomelan, and manganite associated with pyrite, galena, and chalcopyrite. Gangue minerals mostly are dolomite, quartz, calcite, barite, and amorphous silica. Magnetic survey reveals a high-positive magnetic anomaly (up to 2900 nT) which coincides with the location of a magnetite-enriched metagabbroic body, east of the study area. Interpretation of the magnetometry results using geological evidence points to an asymmetric anticline, and occurrences of hematiteare found on its limbs. the ore samples have higher Ba, Pb, Si, and Sr contents, and lower Co, Ni, P, and Ti concentrations .Our results indicated that the mineralization form during the three metamorphic, hydrothermal, and supergene processes, respectively. Based on mineralogy, textures, and chemical variations, Band-e-Cherk mineralization is similar to those typical of hydrothermal deposits where the circulation of fluids into the fractured Anarak metamorphic complex has provided the conditions for the formation of iron and manganese mineralization.

Salardol manganese deposit is located 20km west of Aleshtar in the radiolarite subzone of Kermanshah ophiolite zone. The rock units include radiolarite, breciaition limestone and Cretaceous units. Manganese deposits are seen in the form of irregular lenses as interlayers with radiolarites. Manganese mineralization is visible in three generations. The first generation is syngenetic and is formed interlayer with radiolarity naps. The second and third generations are epigenetic, which can be seen in the form of streaks and mainly within the faults and seams and cracks of radiolarity. Mineralogically, XRD and SEM are important manganese paragenes including Ramsdellite, Romanechite, Rhodochrosite, Jacobsite, Bixbyite and the most important gangue minerals are quartz and calcite. Good agreement between Salardol manganese deposit and hydrothermal deposits has been confirmed by trace elements geochemical data, distinguishing diagrams and elemental ratios. The use of major and minor element ratios indicates the thermal conductivity of Salardol manganese reserves. Na/Mg ratio indicates the effect of fresh water on the formation of manganese reserves. The distribution pattern of normalized REE relative to chondrite indicates a positive Ce anomaly with an average of 20.1 and a negative Eu anomaly with an average of 0.47, which is clearly consistent with manganese hydrothermal deposits. According to the available evidence, the formation of Salardol manganese deposit due to the synthetic placement of primary manganese in the radiolaritic host rock and the epigenetic processes resulting from tectonic activities and under the influence of hydrothermal fluids has led to the formation of fossil-type reservoirs.

In this study, ZnS/MoS2 nanocomposites were synthesized by hydrothermal and ZnS/MoS2/Fe3O4 nanocomposite by chemical co-precipitation methods. ZnS nanoparticles were synthesized initially and then loaded with MoS2 nanostructure. After that ZnS/MoS2 product was mixed by Fe3O4 nanoparticles and the final product that obtained, was ZnS/MoS2/Fe3O4 nanocomposite. XRD, FTIR, TEM, BET and Raman Analyses were used to identify and characterize the samples. Photoluminescence spectroscopy was employed to investigate the optical properties of both composites. The infrared Fourier transform spectra showed a well developed Zn-S, Fe-O and Mo-S bonds. X-ray diffraction pattern confirmed the presence of cubic structure for ZnS and Fe3O4 and hexagonal structure for MoS2. Electron microscopy images well confirmed the formation of nanostructures. Based on PL spectroscopy, the intensity of the luminescence peak decreased, which could be due to a decreases in the electron-holes recombination percentage of the triplet sample compared to the binary sample. Photocatalytic activity of ZnS/MoS2/Fe3O4 on degradation of methyl orange (MO) and acid brown (AB) dye degradation was investigated using UV radiation. The sample showed good photocatalytic activity and can be easily recycled due to its magnetic properties, which can be used as photocatalyst in other reactions.

Shurab Kabir manganese deposit is located 60 km northeast of Shahrekord, the center part of Sanandaj-Sirjan zone. The oldest rocks include metamorphic shale, sandstone, limestone and dolomites of Permian. Permian units have been thrusted on the younger units (Jurassic shale, sandstone, and conglomerates with andesitic intercalation) by trust faults. Mineralization has occurred at sedimentary and metamorphic units as veins, masses and stockwork. The mineralization contains pyrolusite, psilomelane, manganite and goethite, hematite, magnetite with calcite and quartz. Alterations is carbonate and siliceous. The primitive mantle normalized pattern of REE indicates negative Ce anomaly due to oxidation and acidic environment, and a weak negative Eu anomaly due to the distance of hydrothermal fluid from the origin. also primitive mantle normalized pattern of elements of the studied samples show enrichment of Ba, La, Sr, Pb and depletion of Ti, Nb, Rb, Ce and Nb. All of data, field, microscopic and geochemical data indicate hydrothermal fluids for formation Shurab Kabir Mn deposit.

In this study, the effect of surfactant on the structural and photocatalytic properties of bismuth ferrite made (BiFeO3) by hydrothermal method at a temperature of 180 °C and a concentration of 4 M was investigated. The surfactants studied in this paper are ethylene glycol and sodium dodecyl sulfate. The results of diffraction pattern analysis showed that the samples have a rhombic perovskite structure distorted with space group R3c. Also, high purity bismuth ferrite was made at 180 °C and 4M concentration without the presence of surfactant. FESEM results showed that the particle size decreased with the presence of surfactant. The optical and photocatalytic properties of the samples were also investigated by UV-Visible analysis. The results showed that the amount of optical gap increased in the presence of surfactant and was recorded in the range of 2.7-2.8 eV for these samples. The photocatalytic properties of the samples were also investigated in Congo red at a concentration of 10 ppm. The results showed that ferrite bismuth made in the presence of sodium dodecyl sulfate had the most damage.

In this research, Graphene/ Bismuth aerogel nanocomposite was fabricated by hydrothermal method and it’s structural, magnetic and photocatalytic properties were investigated. For this purpose, aerogel of nanocomposites were prepared with a concentration of 4 for graphene oxide and concentrations of 0.2, 0.5 and 1 mg/ml for Bismuth ferrite. Phase and structural studies with XRD and FT-IR analyzes confirm the formation of bismuth ferrite with a rhombohedral structure of perovskite type and reduction of graphene oxide. The SEM images show the porous structure of graphene aerogel well. TEM analysis confirms the composite of bismuth ferrite nanoparticles in the structure of graphene aerogel. The energy gap of the samples was calculated from the results of UV-Visible spectroscopy. Based on the parameter measured by the vibrating sample magnetometer (VSM), it shows a decrease in the magnetization saturation of bismuth ferrite nanoparticles after composite with graphene aerogel. Methyl blue decomposition was evaluated by bismuth ferrite nanoparticles and graphene/ferrite bismuth nanocomposites using UV-Vis apparatus. The best photocatalytic performance of graphene/bismuth ferrite aerogel is in the sample with 0.5 mg/ml concentration.

Temelieh area is located about 20 Km northwest of Selseleh (Lorestan Province). Geologically, the area is a small part of the Harsin radiolarite complex. Petrography consists of radiolarite, peridotite, gabbro, plate dikes, basalt and andesite, limestone, and marble. Manganese mineralization occurs as vein-veinlet and is mainly formed in faults, joints, and fractures that crosscut in radiolarites. Based on mineralogical studies, the manganese paragenesis is composed of pyrolusite, psilomelane, todorokite, cryptomelane, lepidocrocite, and manganese oxide-hydroxide (housmanite, hydrohousmanite, Manganite). The essential waste minerals are calcite and quartz. Based on geochemical data from major and trace elements, using different distinguishing charts and elemental ratios, there is a good relation between the manganese-rich region and the hydrothermal deposits. On the other hand, calculation of element designated ratios like Mn/Fe )mean 0.92), Ti/Al (mean 0.01), Co/Ni (mean 0.97), Co/Zn (mean 0.28), U/Th (mean 0.73), La/Ce (mean 0.32), LREE/HREE (mean 8.64) and ΣREE (mean 56.53) indicate Temelieh manganese ore is hydrothermal. Comparison of the REE normalized pattern of Temlieh manganese ore with other manganese deposits in the world indicates the hydrothermal origin of this deposit. REE distribution pattern indicates Ce positive anomaly with mean 24.5 and Eu negative anomaly with mean 0.54 that is compatible with hydrothermal manganese deposit. Accordingly, ore-forming fluids could be originated from meteoritic or magmatic water circulating through volcanic rocks, dissolve manganese and other metals and, while rising from suitable areas, deposits them in along the fault planes and fractures.

The Shamsabad manganese-bearing iron deposit is located 36 km south-east of Arak city, in the Sanandaj-Sirjan Zone. In order to determine the origin and ore-forming processes of the deposit, in addition to petrographic and mineralogical studies, geochemical studies for major, trace and rare earth elements (using LA-ICP-MS method) were done on ore samples. The ore is lens form and strataband, occurring in thick-bedded to massive, orbitolina-bearing Early Cretaceous limestones. Hematite, limonite, goethite and pyrolusite are the main ore minerals. Hematite is more abundant than other minerals. The colloform texture and lamination of the ore are evidences for volcanic-sedimentary origin of the deposit, and deposition in a marine environment. The presence of todorukite as a primary mineral is indicative of the hydrothermal mediated mineralization. The high Mn/Fe and Si/Al ratios, As, Ba, Cu, Pb and Zn enrichments, and depletion of Co and Ni are similar to hydrothermal deposits. The normalized REE patterns and low ΣREE values (31.40 ppm in average) support that Shamsabad deposit is of hydrothermal origin. Negative Ce and positive Eu anomalies indicate that low temperature hydrothermal fluids have an important role in mineralization. The Co/Ni, Co/Zn, La/Ce, LaN/NdN, DyN/YbN, Y/Ho ratios, and the discriminative diagrams for trace element concentrations are in the range of hydrothermal deposits. this study, it is suggested that the Shamsabad deposit is deposited from submarine hydrothermal fluids.

The Shah-kuh granite batholith (South of Birjand), monozogranite and syenogranite composition, is located on the eastern edge of the Lut block and consists mainly of plagioclase, alkali-feldspar and quartz associated with biotite and tourmaline. The predominant texture of the monozogranite and syenogranite unit is granular to porphyric and granular to micrographic, respectively. Metapelite rocks, host quartz-tourmaline veins, show porphyroblastic texture. Metapelite hosted tourmalines are in the range of dravite and alkaline tourmalines, while granitoid-hosted tourmalines are shorlite type. Presence of properties such as higher Mg content than Fe, low Fe/(Fe + Mg) value, low Al content, tendency towards outside of alkaline depletion and proton depletion vectors and FeO/(FeO + MgO) values less than 0.6 in metapelite host tourmaline veins indicates fluid-rock interaction in an open system far away from the granitoidic body and magmatic-hydrothermal origin. Also, characteristics, such as high Fe/(Fe + Mg) ratio, lack of zoning and proximity to granitoidic body in tourmaline veins with granitoid host rocks, indicates the separation of penomatolitic fluid containing boron (B) from granitic magma and its proximity to B-bearing fluid source. The results of tin analysis in some rock units of Shah-kuh region show that tin mineralization and probably tungsten (more than 500 ppm) are concentrated in quartz-tourmaline veins located in the north and northwest of the study area which is not economic grade (4500 ppm) in the high grade tin deposits.

The Qara Sabalan manganese deposit belongs to the Qara Dagh-Sabalan metallogenic zone and is located in the eastern part of this zone (north of Meshginshahr). Geology of the area include volcanic (pyroclastic) rocks and the small outcrop of sub volcanic bodies (quartz-monzodiorite) with Eocene to Oligocene age. Mn deposit is hosted within the trachyandesite and tuff. Mn mineralization occurs as veins-veinlets, disseminated cement filler of brecciated zones. Faults and fractures with the trend of NE-SW have played a major roles for the formation of manganese mineralization. The main manganese mineralization consists of pyrolusite, manganite, psilomelane, hematite and goethite. variety of textures, such as open-space fillings colloidal, nodular, replacement and brecciation, are observed which are evidences for epigenetic manganese deposition. Rare earth elements patterns show a specific negative anomaly of Ce (0.04-0.13, mean 0.08) and a relatively positive Eu anomaly (0.28-0.38, mean 0.32). The significant geochemical characteristics of ore, such as Mn/Fe (mean 41.22), Co/Ni (mean 5.24), Co/Zn (mean 0.28), U/Th (mean 0.68), La/Ce (mean 1.77), Lan/Ndn (mean 2.82), Dyn/Ybn (mean 3.16), LREE/HREE (mean 9.51), ΣREE (mean 63.70), reveal a hydrothermal source for Qara Sabalan Mn mineralization.

The ChahMusa region is known as the head of the mining of Toroud-ChahShirin volcanic belt which has been a source of copper mineralization for a long time. The outcroped rock units in the studied area are including tuffs and andesitic breccia, , andesitic dacite, andesitic basalts, andesites, micro-quartz diorite and gabbroic dykes. Copper carbonates are the main minerals in the region, and chalcopyrite, sphalerite, galena, bournite and covellite minerals are minor minerals in this region. Dominant alterations of the studied area are including argillic, propylitic, and calcitization. This study has been carried out on quartz and calcite minerals as syngenetic waste of sulfide minerals. The transfer of metals in the mineralizing fluids was mainly carried out by chloride complexes. As well as, eutectic data show that, there are two soluble systems probably active in the region, which is consistent with the H2O-NaCl-KCl and H2O-CaCl2-MgCl2 systems. Measured eutectic temperatures indicate that there are probably two types of fluids in the area. The performed detail temperature on the fluid inclusions of studied area indicates that the salinity of these fluids varies from 3 to 26% by weight, equivalent to NaCl, and the homogenization temperature of fluid inclusions is between 130 ° C and 470 ° C. Obtained evidence show that sulfide ore formation in this region is from epigenetic type and may have occurred under conditions epithermal. The fluid inclusions study has led to the formation of deposits as a result of boiling, cooling during the and mixing whit atmospheric waters.

Zamanabad area is located in southern of Hamedan Province and belong to Sanandaj-Sirjan magmatic-metamorphic Zone. Lithologic units of this area comprising slate, phyllite, andalusite-garnet bearing schists, sillimanite bearing schists, hornfels, pegmatitic unit and recently alluviums. The most important of geological unit is Alvand granitoid pluton at age middle Jurassic. Presence of tourmalines with brown-green pleochroism and blue automorphic tourmalines such as probably indicolite is the specific features of tourmalines of Zamanabad area. Based on the microprobe analysis and multiple diagrams on tourmalines, the combination of tourmaline in granitic pegmatite is schorl and a few close to foitite. By the way, tourmalines in hornfels pegmatites are schorl and close to dravite. It was studied that tourmaline in granite pegmatites is alkaline and empty site whiles tourmaline in hornfels pegmatite is alkaline. Features such as automorphism, absence of chemical zoning, Al, Fe/Fe+Mg increase and decrease in X-site and host granite lack of Li and pegmatite and aplite related its show that these tourmalines have magmatic origin.Also, alkaline, without of X-site and further amount of Mg and a lesser amount of Al and Fe/Fe+Mg in tourmalines of hornfels pegmatites compatible to metapelites poor of Ca, metapesamites and tourmaline–quartz rocks show this complex have hydrothermal origin.

MoS2/Ag2S nanocomposite is synthesized by hydrothermal method without using inert atmosphere from green synthesized Ag nanoparticle. The synthesized samples were characterized and studied by X-Ray Diffraction (XRD), Fourier Transform-Infrared Spectroscopy (FTIR), Scaning Electron Microscope (SEM) and Transmision Electron Microscope (TEM) analysis. The optical properties of the samples were investigated by using UV-Vis absorption spectra. Also the formation of Ag nanoparticles via Sesbania sesban extract is confirmed by UV-Vis spectra. The hexagonal crystal structure of MoS2 and the monoclinic structure of Ag2S nanoparticles was confirmed by the result of X-ray diffraction pattern. SEM and TEM images showed the morphology and loading Ag2S on MoS2 structures. The photocatalytic activity of nanocomposite against of the methyl orange and methylene blue colors was evaluated by UV light. The results showed that the MoS2/Ag2S nanocomposite is a good destructive dye of methyl orange and to some extent methylene blue with UV light.

Baghalbid iron mineralization is one of the eastern anomalies of Sangan iron mines. This area is geologically located in the north-eastern part of Lut block. In this area, Paleozoic and Mesozoic units such as schist, phyllite and sandstone are in contact with Tertiary igneous units and Neogene sedimentary rocks. The iron mineralization occurs as hematite in the upper part of a brecciated volcanic layer with a length of more than 1 km. The footwall rocks contain breccia, tuff and sandstone and hanging wall rocks contain subvolcanic granodioritic dikes. The hematite occurs as open space filling in breccia, indicating that the iron mineralization is classified as epigenetic type. Barite, calcite, and quartz were also formed in fractures and open spaces of iron-bearing horizon. In addition to the iron, copper mineralization occurs as quartz veins containing chalcopyrite and malachite in footwall rocks. The iron oxide contents vary from 8 to 55 wt. % in the iron-bearing horizon. In mineralized rocks, the amount of chromium, vanadium and phosphorus is relatively low, while those of barium, arsenic, silver and antimony are relatively high, and LREE and LILE show enrichment relative to HREE and HFSE, respectively. According to geological, mineralogical and geochemical characteristics, ore texture and structure, REE pattern, the Baghalbid iron mineralization is classified as hydrothermal type. The iron was probably leached from pyroclastic rocks by hydrothermal fluids and was re-concentrated in the upper permeable breccia and conglomerates.

It is generally understood that manganese deposits have a diverse origin, based on their mineralogy, chemical composition and tectonic setting. Marine Mn-bearing deposits are classified as hydrogenous, hydrothermal and also biogenetic-bacterial deposits (Bonatti et al., 1972; Hein et al., 1997; Bau et al., 2014; Polgári et al., 2012; Schmidt et al., 2014). Hydrogenous processes can form ferromanganese crusts, which result from slow precipitation of seawater at the seafloor often via microbial mediation (Toth, 1980; Dymond et al., 1984; Bau and Dulski, 1999; Usui and Someya, 1997; Hein et al., 2000; Jach and Dudek, 2005). Diagenetic manganese deposits occur as nodules and precipitate from hydrothermal solutions or pore water (Polgári et al., 1991; Oksuz, 2011; Polgári et al., 2012), whereas hydrothermal ore deposits are stratabound or occur as irregular bodies and epithermal veins, where they are formed in a marine environment near spreading centers, intraplate seamounts or in subduction-related island arc setting (Roy, 1992; Roy, 1997; Hein et al., 2008; Edwards et al., 2011).

Eighteen Ore samples (~ 500 g each) were collected systematically from the Gezeldash Daghi manganese deposit. All these ore samples were taken representatively from the surface outcrops ore beds in different places for geochemical analyses. Ore samples were powdered under 200 meshes and analyzed at Iran mineral processing research center laboratories, Tehran. After being prepared by the Lithium Borate Fusion method, their major oxide and trace element contents were determined with ICP-OES. The results of the analyses are given in Tables 1 and 2.

The deposit is hosted in various lithology and horizons consisting of: 1) tuffite interlayered with limestone, 2) conglomerate and sandstone lithology into volcano-sedimentary basin located at 25 km northwest of Marand city (N38°35ʹ40ʺ, E45°42ʹ40ʺ). Major and trace element assessments show that hydrothermal solutions were effective in the formation of the Gezeldash Daghi manganese deposit. Also, field observations reveal that manganese mineralization occurred as laminated-layered and fracture-filling form in limestone and tuffite at horizon I and the space-filling form between conglomerate clasts and veinlet form in sandstone at horizon II with quaternary age. Therefore, it can be concluded that hydrothermal solutions were caused in the formation of the manganese deposit which may be described as related to volcano-hydrothermal occurrence.

Manganese deposits are classified as hydrogenous, diagenetic and hydrothermal deposits based on their mineralogy, chemical composition, and tectonic setting (Hein et al., 1997). Hydrogenous manganese deposits have slowly precipitated from seawater (2-10 mm/Myr) (Ingram et al., 1990). These deposits contain iron and are poor in manganese oxide. The Mn:Fe ratio is ~1 and Ni and Cu are represented by high concentrations (>3000 ppm) (Hein et al., 1997; Usui and Someya, 1997). Diagenetic manganese deposits occur as nodules and have precipitated from hydrothermal solutions or pore water within altered sediments (Klinkhammer et al., 1982). These deposits are usually related to organic matter oxidation and formation of Mn carbonate minerals (Polgari et al., 2012). Hydrothermal manganese deposits have directly precipitated from low-temperature hydrothermal solutions (Hein et al., 1997; Ingram et al., 1990). These deposits are generally laminated and stratabound or occur as irregular bodies and epithermal veins (Hein et al., 1997). Diagenetic and hydrothermal deposits are characterized by high Mn:Fe contents and low trace metal concentrations (Hein et al., 1994; Hein et al., 1996). Although there are similarities between these two deposit types, they are mostly distinguished by their morphologic, tectonic and growth rates (Kuhn et al., 1998). The Joun Abad manganese deposit is located 16 km southeast of the Joun Abad village, 72 km north of the city of Khash in the eastern longitude of 61° 06´ 0.7ʺ and the northern latitude of 28° 51´ 2.3ʺ. This zoning is structural-sedimentary that is located in the middle part of the flysch zone of Eastern Iran. In this paper, major, trace and rare earth element compositions of ores have been used as an approach to determine the conditions of ore formation. Twenty representative ore samples (~450 g) were selected from the Joun Abad manganese deposit. Geochemical analyses were made of samples taken from different surface mineral outcrops at various locations. Crushed and grounded ores (under 200 mesh) were analyzed at the Kansaran Binaloud Laboratories, Tehran, Iran. Major oxide and trace element contents were determined by X-Ray Fluorescence (XRF) and Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), respectively, and the REEs were analyzed using the Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) method. The Joun Abad manganese deposit is located 16 km southeast of the Joun Abad village, north of the city of Khash, and with respect to structural-sedimentary zoning in the middle part of the flysch zone of Eastern Iran. The host rocks of manganese layers are red shale, manganese mineralization is visible on the upper parts, as interlayers and/or contamination. The geometry of the ore mineral is in layered form and it is often conformable with units including red shales. The chemistry of the major elements, Mn:Fe and Si:Al ratios and the positive correlation coefficients between Al2O3, TiO2 and Fe2O3 indicate that they were affected by hydrothermal processes in a shallow environment together with entering mafic clastic materials in sedimentary basin where the ore formed. All trace element diagrams show low contents of elements such as Ni, Co and Cu in the manganese ores. The deposits of the study area in these diagrams plot in the field of hydrothermal deposits. Co:Ni, Co:Zn, LREE > HREE contents and total REE and negative Ce anomalies also indicate the role of ore-bearing hydrothermal fluid in the deposit. REE distribution patterns of the deposit are quite similar to those of hydrothermal deposits.

Salt domes are one of the most notable features on the face of Zagros in the south of Iran. In this study the salt of Dehkoyeh, Paskhand and Karmostaj domes located in Larestan based on salt colors were analyzed. In mineralogical studies for the first time two minerals, Sassolite B(OH)3 and Glauberite Na2Ca(SO4)2 which are of today 's fumaroles indexes in different parts of the world, were identified in Dehkoyeh dome as well as Hormuz salt formation. Generally, compared to other existing elements iron has the greatest impact on the changes of salt color. In salts accompanying sassolite and Glauberite certain minerals with temperature range between 50°C to 60°C were identified. Sea floor fumaroles has probably played important roles in formation of Hormuz salt in infra-Cambrian era. In all probability this fumarole was the main supply of ions needed for salt formation and this fact justifies the emergence of large volumes of Hormuz salt in a relatively short time.

The Shahrestanak Mn deposit is located in southern Qom province، 12 km southwest of the city of Kahak. Based on geological-structural divisions of Iran، the deposit belongs to central volcanic belt or Urumieh-Dokhtar zone. The Venarch deposit is one the most important known manganese deposits in Iran. The Sharestanak and Venarch deposits are spatially and temporally related to each other، and have similar geology، mineral texture and structure، host rocks، relationships with faults، and depositional environment. So، their magmatism and deposition conditions can be related to each other. Since no systematic study on the Shahrestanak deposit had been performed before discussing its geological and geochemical characteristics، here it is being attempted to study the geology، petrography، geochemistry of major، minor and trace elements، and Rare Earth Elements (REE) of ore، to distinguish the depositional environments and genesis of this deposit and to compare REE of ore in this deposit with other deposits. Sampling and method of study: Fourteen samples of manganese ore were selected for geochemical study and analyzing of major، minor، trace elements and REE by ICP-AES and ICP-MS and were sent to SGS Co.، Toronto. Detection limits for major elements and trace elements are 0. 01% and 0. 05ppm، respectively.

The deposit is characterized by various lithology and stratigraphy units، consist of: 1) Middle to -Upper Eocene volcano-sedimentary rocks، 2) Oligocene lower red conglomerate and sandstone، 3) Oligo-Miocene limestone and marl (Qom Formation)، and 4) Eocene and Lower Miocene basic to intermediate dykes. The most abundant minerals of the deposit are braunite، hausmannite، pyrolusite، and manganite. Evidences such as high Mn/Fe (11. 33) and Si/Al (4. 86) ratios، low contents of trace elements specially Co (11. 40 ppm)، Ni (24 ppm)، Cu (81. 85 ppm)، and Ce، with high amounts of SiO2، Mn، Fe، Ba، Zn، As and Sr، all represent hydrothermal processes. It seems that hydrogenous processes have not had significant role on the genesis of the Shahrestanak Mn deposit. During deposition of Fe and Mn from hydrothermal solution، they separated from each other and produced different Fe/Mn ratios in sedimentary exhalative deposit (SEDEX). The Fe/Mn ratios are 5. 7 to 40. 35 (ave.، 11. 33). Very high and very low ratios of Fe/Mn can be interpreted as fractionation and separation of these two elements from transportation during hydrothermal activities and mineralization. So، high Fe/Mn ratios here can be considered as in submarine hydrothermal deposits. Cann et al. (Cann et al.، 1977) suggested that Fe/Mn ratios in volcano-sedimentary and hydrothermal deposits are so variable and characteristic. Hydrothermal deposits are in close relationships with ferruginous silica gel which itself formed from submarine hydrothermal outpouring and discharging of metals in marine sediments. So، Si wt. % versus Al wt. % is high in exhalative activities. The average Si/Al ratio is 4. 86 in the Shahrestanak deposit which is in the range of hydrothermal deposits (SEDEX). Nicholson (Nicholson، 1992) suggested Na versus Mg content diagram for distinction between fresh water، shallow and deep marine environments. Bonatti et al. (Bonatti et al.، 1992) introduced Fe-Mn- (Co+Cu+Ni) *10 ternary diagram for distinction between marine sedimentary and hydrothermal Fe-Mn deposit. According to this diagram، hydrothermal oxides depleted in Ni، Cu، Co and zinc relative to sedimentary-marine deposits. Nicholson (Nicholson، 1992) suggested that hydrothermal Mn deposit distinguished with Zn، V، Mo، Cd، Li، Sr، Sb، Pb، Cu، Ba، and As and sedimentary deposit with enrichment in Ni، Cu، Co، Sr، Mg، Ca، Na and K. Hydrogenetic ferromanganese deposit has higher enrichment of Ni، Cu and Co relative to hydrothermal (exhalative) deposit. Low contents of Cu، Co and Ni indicate low input of these elements from hydrothermal activities and derivation of Zn from hydrothermal source. As (Co/Zn) - (Co+Cu+Ni) diagram، the samples from Shahrestanak deposit show close similarities with hydrothermal deposits which in turn show common genesis. Using Pb versus Zn diagram، dubhite (deposits derived from previous mineralized sequence) can be distinguished from other Mn oxide (hydrothermal or supergene) deposits. The dubhite deposits have high Pb/Zn ratios and more than 1 percent Pb and Zn contents. Meanwhile، other types of deposits like shallow marine deposit، hot springs، SEDEX، weathered deposits have lower contents of Pb and Zn. The Shahrestanak deposit has more similarities with SEDEX and shallow marine deposits.

Geological and geochemical evidences show that deposition of ore occurred by submarine hydrothermal activities in Neotethys oceanic basin during Middle to Upper Eocene in calcareous tuff with intercalation of micrite and calcareous limestone. For the genesis of the deposit، it can be stated that the pillow basalt and andesite lavas were leached by hydrothermal activities and Mn، Fe، Si، Ba، Sr and As entered in sedimentary basin by exhalative – volcanic activities through faults، then by regression of the sea and forming oxidizing condition، primary oxide-hydroxide Mn-minerals are deposited.

The hydrothermal method due to advantages of low reaction temperatures and achieving fine particles in synthesized samples was used. Li2SiO3 has orthorhombic structure with Cmc21 space group and cell parameters a = 9.392, b = 5.397 and c = 4.660Å.  The structure, size and morphology of nano particles were investigated by XRD, FT-IR and SEM analysis methods. In addition, the cell parameters of lithium metasilicate nano particles were determined by CELREF software version3. Optical properties of synthesized silicates were investigated by UV-vis and Pl analysis methods.