جستجوی مقالات مرتبط با کلیدواژه « ارومیه دختر » در نشریات گروه « زمین شناسی »

Dokhan region is located in the west of Nobaran (Saveh), between Urumieh-Dokhtar and Sanandaj-Sirjan zones. In this study, the geochemistry of whole rock and the chemistry of clinopyroxene, olivine and nepheline minerals in Dokhan Quaternary volcanic rocks have been studied. From Petrographic aspect, the studied rocks are mostly melanephelinite and olivine melanephelinite. The chemical composition of rocks include foidite, tephrite and basanite. These rocks are relatively rich in CaO and MgO and poor in SiO2 and Al2O3. Their olivine is chrysolite and clinopyroxene is diopside. The parent magma of these rocks is derived from a metasomatized garnet lherzolite mantle that is somewhat contaminated with the continental lithosphere. Temperature-pressure measurement of these rocks using the composition of minerals shows the temperature of 1200° C to 1250 ° C and pressure of 5 to 10 Kb. These rocks are probably formed in the intercontinental environment after the subduction of Neotethys and the collision of the Africa-Arabia and Eurasian continents.

Dalfard granitoids are located in the south-east of Kerman province and in the margins mainly include quartz diorite. Quartz diorites contain main minerals plagioclase, amphibole and biotite  and this work reveals that the rocks in this area are I type granitoides and they belong to calc-alkaline magmatic series. The enrichment of LREE relative to HREE, high contents of LILE relative to HFSE and anomalies of Nb and Ti in spider diagrams show that the Dalfard quartzdiorites are formed in an arc setting environment. The CaO/(MgO+FeOt) and Al2O3/(MgO+FeOt) ratios (0.55 and 1.36 respectively) show that the parent magmas were formed by the partial melting of basaltic rocks of the lower crust and mantle fluids/melts also participated in their formation. Based on geochemical data such as La/Yb(N) and Th/Yb(N) ratios (4.4 and 6.5 respectively), these magmas are related to pre-plate collision environment and formed in the mature Volcanic arc setting at a depth of about 40 km at the supra subduction zone of the Neothetys oceanic lithosphere and then, they ascent to the higher levels of the crust and passed fractional crystallization.

Tourmaline is an indicator mineral of pegmatite, granites and pneumatolytic veins. In metamorphic rocks, it is formed by the process of boron metasomatism and in sediments by the recrystallization of destructive particles. This mineral crystallizes in various temperatures, pressures and geological environments so can be widely used in lithological studies.The study areas are part of the geological map of Kashan located in the west of the volcanic belt of Central Iran (Urmia-Dokhtar belt). A number of studies have been carried out regarding the geological and petrological of the areas of study: Among those, petrology and geological studies of metamorphic aureole in Qohroud granitoid (Ahankoub, 2003), petrography and petrology of Qohroud plutonic rocks (Jafari, 2001), the type of garnet zoning in skarns of Qohroud Intrusion (Farazdel et al., 2005) and geochemistry and petrology of mafic-intermediate intrusions in mineralized region of Qamsar, Kashan Yar-Ali (2016) are more notable. The purposes of the present study are to determine the origin of tourmalines from the study areas on the base of their petrographic and geochemical characteristics as well as their structural formula and to compare these minerals as well.

Following field observations, 25 thin sections were prepared for mineralogical and textural studies using Olympus polarizing microscope (BH2). 10 samples of tourmalines were analzyed by XPM analysis at Binalood Company. The results of microprobe analyses of tourmalines from hornfelses (Ahankoub, 2003) carried out at the Oklahoma University (USA) were also used for the present study. All these data are given in Tables 1 and 2.

The areas under investigation are predominantly compose of sedimentary, metamorphic (hornfels, marble, skarn) and intrusive (granodiorite, monzogranite, tonalite) rocks. Plagioclase, orthoclase, quartz, hornblende, and biotite as major with sphene, zircon, tourmaline and opaque as minor minerals are dominant. Tourmalines in these areas are metasomatism in nature and as needles and small crystals. are mainly found in fractures. Tourmaline crystals with zoning, formed in post-crystallization and hydrothermal stages, were subjected to influence of boron-rich solutions presumably point to mixing of fluids in open systems. Green tourmalines replaced feldspars possibly caused by tourmalinization in the pneumatolitic stage by reactions of boron with wall rocks.Based on X position and Ca, Na, K contents, most of tourmalines are alkaline. The chemical composition of tourmaline in hornfels is mainly dravite and in granitoids is dravite with a tendency towards schorlite. The formation of tourmaline instead of biotite and chlorite in metamorphic rocks shows the its formation as a result of reactions of boron fluids with aluminosilicates. The studied tourmalines lie below the line  and therefore, have Al substitution in the Y position. As the Fe-Mg-Ca and Al-Mg-Fe diagrams display these tourmalines are mainly plotted within the metapelites and metapesamites in calcium poor quartz- tourmaline rocks. The ratio of FeO / FeO + MgO tourmalines from the hornfels is between 0.58 to 0.6 (ave. 0.59), which confirms they have crystallized in an open magmatic system with the presence of boron with an external origin and indicates the involvement of atmospheric water during their formation in the hydrothermal system. This ratio in tourmalines from the granitoids are between 0.56 to 0.69 (ave. 0.63), which can indicate the formation of these tourmalines during the mixing of magmatic and hydrothermal fluids.

The chemical composition of the studied tourmalines based on cationic substitutions is in the range of alkaline tourmalines, which indicates a higher amount of K and Na at position X compared to Ca and confirm their formation in acidic and low temperature conditions. The chemical composition of tourmalines from granitoids is in the range of dravite and schorlite and the chemical composition of tourmalines from hornfels are mainly dravite, which represents the cation exchanges of Fe, Mg in constant values of Ca and Al. The studied tourmalines are located in the range of calcium-poor metapelites and metapsamites and calcium-poor quartz-tourmaline rocks and coexist with the aluminum-saturated phase. Based on the amount of FeO / FeO + MgO in tourmalines, the openness of the system and the presence of boron from an external source is confirmed.

The Mohammadabad deposit is located in vicinity of Delijan in central province and in terms of structural zones of Iran,in the Uremia dokhtar zone. Stratabound Fe-Ce mineralization in brecciated, vein, massive, layered and laminar forms, consists ore minerals such as hematite, pyrite, chalcopyrite and magnetite ,is seen in lower Eocene volcano sedimentary unites. Amounts , ratios and diagrams of trace elements and rare earth elements show hydrothermal mineralization with the predominance of magmatic fluids. The values of δ34SCDT of sulfide minerals (-2.76 to1.51 ‰) and suggest the magmatic source for sulfur or mineralizing fluid with magmatic sulfur. The values of δ13C (mean 3.61 ‰), δ18O(mean12.946‰) related diagrams show a magmatic source for carbon, hydrothermal genesis for calcite and a mineralizing fluid dominantly magmatic source. above evidences,وthe location of the region in tensile tectonic regime in western edge position of uremia dokhtar magmatic arc during the Eocene and presence of magmatic mass in the depths of the region with high potential for iron and copper mineralization , sulfur supply ,also has played role of a heat engine to circulating and transfer of mineralizing fluids to the sea bed. Offers exhalative-hydrothermal processes model for deposit genesis in Eocene volcano sedimentary units

Granitoids are one of the most abundant and common igneous rocks in the continental crust and they formed the world's largest batholiths. They are widely distributed in Precambrian to Cenozoic orogenic belts (e.g., Raymond, 2002), but some are formed in non-orogenic zones (Blatt et al., 2006). Because much of the continental crusts in orogenic belts are composed of granitoids, they are of particular importance in explaining the petrologic processes in orogenic belts.Cenozoic magmatism of Urmieh-Dokhtar magmatic arc is intruded by Oligo-Miocene plutonic rocks in some regions (Arvin et al., 2004). An outcrop of Oligo-Miocene granites is found in Zafarghand area in the southeast of Ardestan in Isfahan Province. Sarjoughian et al. (2018), Aminoroayaei Yamini et al. (2017), Sadeghian and Ghaffary (2011), Khalatbari Jafari et al. (2016), and Ghalamghash et al. (2019) suggested that this magmatism is a result of lower crust melting during mantle wedge metasomatism, occurred by Neo-Tethys subduction.This study aims to investigate the Oligo-Miocene granodiorites of East Bideshk, which is exposed in the central part of the Urumieh-Dokhtar magmatic arc in the northeast of Isfahan city. Despite the tectonomagmatic importance of this pluton in completing the geological history of Urumieh-Dokhtar magmatic arc, there are no comprehensive petrological studies performed on Bideshk granitoid. Thus, this study considered the mineralogy, geochemistry, tectonic environment, and origin of this granodiorite.

Microprobe analysis of the minerals was performed using a CAMECA SX 100 model with 15 kV accelerator voltage and 20 nA current at Stuttgart University, Germany. The Minpet software was also used to calculate the structural formula of the minerals and plot the diagrams. Intact and less altered rock samples are selected for geochemical analysis of major, trace, and rare earth elements by ICP-MS and ICP-OES methods in the geochemical laboratory of ALS Chemex in Ireland. The LOI values are also obtained by the gravimetric method. Fe2+ and Fe3+ are calculated based on the method by Middlemost (1989). Abbreviations for minerals are from Whitney and Evans (2010).

The Eocene Granodiorite - diorite rocks outcrop in the east of Bideshk area, in the northeast of Isfahan, and along the Urumieh-Dokhtar magmatic zone. According to lithological studies, they are mainly composed of granodiorite with predominant texture are granular, granophyre, and porphyroid.The major minerals are plagioclase, quartz, K-feldspar, hornblende, and biotite. Accessory minerals include magnetite, and apatite. Calcite and chlorite are the secondary minerals. Embayed plagioclases and quartz with rounded margins and plagioclases with oscillatory zoning, sieved texture, and dusty rims show non-equilibrium conditions during magma mixing. The composition of calcic amphiboles in these rocks is actinolite- tremolite, hornblende, and magnesio- hornblende. Plagioclases in the rocks of the east of Bideshk are andesine to labradorite in composition, and some show oscillatory zoning. Thermobarometry results indicate pressure, temperature, and crystallization depth decrease from the core (average ~ 3.01-3.63 kb, 685-732℃) of hornblende crystals. Geochemical investigations show that this granitoid is metaluminous, calc-alkaline, and I-type. The primitive mantle and the chondrite- normalized patterns of Bideshk whole-rock samples show enrichment of LREE against HREE. It is in accordance with magmatism in a subduction zone. Geochemical diagrams and variation in Rb content relative to Nb can also indicate a subduction-related magma source and mantle wedge metasomatism in the east of Bideshk, during Neo-Tethys subduction beneath central Iran.

The Urmieh- Dokhtar magmatic belt (UDMB) lying parallel to the Zagros suture zone is resulted from the subduction of Neotethyan oceanic lithosphere beneath the southern margin of Eurasia. The studied volcanic rocks of the Razan- Avaj area are part of UDMB magmatism. These rocks are composed of olivine-basalts, basalts and occasional trachyandesites with alkaline nature. The interlayered stratigraphic relationships of volcanic horizons with sediments of Qom Formation implies Oligo-Miocene age. Major and trace element contents of volcanics and chemical modeling are indicative of significant role of olivine + clinopyroxene + plagioclase fractional crystallization (35-45%) in melt compositional trend. Bulk rock chemistry of theses rocks displays LREE/HREE enrichment and lack of HFSE negative anomaly similar to oceanic island basalts (OIB). It seems that after Eocene magmatic flare-up with obvious magmatic arc signatures in UDMB, during the Oligo-Miocene the origin of magmas has shifted to a deeper asthenospheric mantle. Probably, after the initial stages of the Arabian-Eurasian plate collision in the Late Eocene-Early Oligocene and the slab roll-back, an upwelling asthenospheric mantle is injected into the mantle wedge and is weakly affected by the subduction material, which is the source of Oligo-Miocene melts.

The Manto-type copper deposits of the Qom-Saveh region are located in the central part of the Urumieh-Dokhtar magmatic arc and occurred in the Eocene volcano-sedimentary sequence. The most important deposits in the studied area are East Narbaghi, Khankishi, Veshnaveh, and Kahak. The geometry of mineralization is stratabound and hosted in the silty tuff, tuff breccia, andesite, lithic crystal tuff, and amygdaloidal andesite basalt. The hypogene ore minerals include chalcocite, bornite, and minor chalcopyrite with vein-veinlet, open space filling, disseminated, and replacement textures. Based on geological studies, two major stages are distinguished for hypogene mineralization. Disseminated and framboidal pyrite formed during the first stage of mineralization which occurred simultaneously with volcanism, sedimentation, and early diagenesis. The second stage of mineralization took place during late diagenesis when copper-bearing oxidized fluids entered into the reduced pyrite-bearing host rock, causing the replacement of the first stage pyrites by copper sulfides. The sulfur isotope composition of sulfide minerals from the East Narbaghi deposit varying from -10.2 to -4.4 ‰ (averaging -6.7 ‰VCDT) indicates the presence of a reduced environment resulting from activation of sulfate-reducing bacteria. The geology, ore mineralogy, alteration characteristics, and sulfur isotopic compositions suggest that the studied ore deposits may be classified as Manto-type mineralization.

Cenozoic volcanic activities in the Urumieh-Dokhtar Magmatic Arc (UDMA) have occurred in three main pulses of Eocene, upper Oligocene-Pliocene, and Pio-Quaternary (Dilek et al., 2010, Sayari, 2015). Magmatic activities in the UDMA until a few years ago were marked with calc-alkaline and occasionally shoshonitic signatures. Recent studies have reported post-collisional adakites in some parts of the UDMA (e.g., Ghadami et al., 2008; Omrani et al., 2008; Sayari, 2015; Sayari and Sharifi, 2018). Since magmatic genesis of calc-alkaline, shoshoitic, and especially adakites are absolutely different, variation in the volcanism nature of Iran is a key to recognition of geodynamic evolution of Iran. This study tries to analyze the volcanic evolution in the central part of the UDMA by systematically processing of geochemical database for three main Cenozoic volcanic pulses.   

Whole rock reliable ICP-MS analysis data from scientific texts having exact location coordinates were gathered to form a geochemical geodatabase which includes 99 samples. This database spatially covers around 200 km in the central part of the UDMA from 51°15´E and 33°47´N (north of Isfahan) to 52°57´E and 32°35´N (east of Isfahan).  

Analysis of the geochemical geodatabase indicates that none of the samples belong to alkaline and tholeiitic magmatic series. About 71 percent of group 1 (volcanic pulse of Eocene) are calc-alkaline, and the remaining 29 percent are shoshonitic. About 67 percent of group 2 (volcanic pulse of Oligocene-Miocene) are shoshonitic, and the remaining 33 percent are calc-alkaline. About 88 percent of group 3 (volcanic pulse of Plio-Quaternary) are adakite, and the remaining nearly 12 percent are both calc-alkaline/shoshonitic (samples CN4, JS13, OG4 and SK1 of Khodami, 2009). Adakitic samples are situated in two areas in Joshaghan-Ghohrud and Kajan-Kahang. Sayari and Sharifi (2018) showed that there is a correlation between UDMA adakites and positive lithospheric thickness anomalies. They showed that adakites in the central part of UDMA are restricted to 4 regions exactly where lithosphere and crust are anomalously thicker than the surrounding. In the areas where adakites lie, lithosphere-asthenosphere boundary (LAB) is situated deeper than 212 km (Sayari and Sharifi, 2018). The geochemical aspect of the studied adakites which are all related to the third volcanic pulse of UDMA shows that they have been derived from the subducted slab. They do not have adakite-like or crust-derived adakites characteristics.

The results indicate that volcanic activities from Eocene to Quaternary have evolved from calc-alkaline to shoshonitic signatures and then turned into adakitic nature. Calc-alkaline and shoshonitic magmatism resulted from partial melting of the mantle wedge, while adakitic magmatism resulted from partial melting of the subducted slab. This means that the origin of the third volcanic pulse has shifted from mantle wedge to slab. According to the La/Sm versus La diagram (Aldanmaz, 2000) calc-alkaline samples have been derived from about 15% partial melting of the spinel-garnet lherzolite, and the shoshonitic samples have resulted from about 3% partial melting of the spinel-garnet lherzolite. Based on La/Yb versus Yb diagram (Bourdon et al., 2002), adakites from Kajan-Kahang have been derived from about 10% partial melting of the garnet amphibolite. Moreover, the Adakites from Joshaghan-Ghohrud have resulted from about 6% partial melting of the hornblende eclogite.

The Oligo-Miocene intrusive masses of northern Sarduieh are located in the Urumieh-Dokhtar zone and the lithology is composed of granitoids include quartzdiorite, tonalite, granodiorite, granite and granophyre. Mineral chemistery studies showed that the amphibole minerals in diorite and granodiorites are calcic in composition and range from actinolite to magnesio-hornblende.  Geochemical and mineralogical results revealed that these bodies have been generated in the lower part of the lower crust at a temperature of 700 to 750 °C, with an oxygen fugacity of -13.57 to -15.76 and a low pressure of 1 to 3 kb. These amphiboles are subduction-related and in accordance to the tectono-magmatic features seen in these massifs, they show characteristics of subduction and active continental margin environments.

The Kalchuye Cu-Au deposit is located in the central part of the Urumieh – Dokhtar magmatic arc. This mineralization is mainly hosted by diorite, quartz diorite and andesite rocks. The mineralization is characterized by chalcopyrite, pyrite, galena and magnetite in the hypogen stage followed by chalcocite, covellite, malachite and goethite in supergen stage. According to the geochemical studies, the Lan/Ybn ratio is between 2.2 to 6.3 and Eu/Eu* varies from 0.7 to 1.1; so that intrusions which are the host of mineralization in the Kalchuye region represent characteristics of magmas in the subduction zone (enrichment of LILE, depletion of HFSE in association with negative Ti anomaly). Fluid inclusion data show the temperature of 150-310 ˚C, salinity of 0.1- 4 (wt%NaCl eq.) and depth of 400m, approximately, for the Klchuyeh deposit. Fluid evolution in the Kalchuye exhibits cooling, surface dilution and boiling. Evidences such as bounded and comb textures in quartz, bladed calcite, hydrothermal breccia, propelitic alteration and fluid inclusion information such as temperature and salinity prove the low-sulfidation epithermal nature for the Kalchuye deposition.

The Dorojin granitoid at the northeastern Isfahan is located in the central Urumieh-Dokhtar zone and within the volcano-sedimentary complex. The Dorojin iron deposit is the one of the several ore deposits that Dorojin granitoid body is caused in its surrounding rocks. According to microscopic evidences, mineral assemblage of wollastonite, garnet, pyroxene (diopside), amphibole, epidote, feldspar, calcite and quartz, Dorojin deposit attributed to the class of calcic skarns that occur during two stages progressive and regressive. Based on electron microprobe analysis, some garnets are andradite (An92-97Gr1-5) in core and andradite-grossular (An53-66Gr30-41Sp2-4) in rim. In the beginning, andradite fluid inclusions with temperature range from 369˚ to 444˚C and salinity range from 11.22 to 12.96 wt.% NaCl eqv., originate from magmatic fluids, while with change in the acidity condition of environment and the opening of system, grandite, epidote and calcite fluids with a temperature between 221˚ and 305˚C and salinity between 0.4 and 10.11 wt.% NaCl eqv., are dominated by mixing and dilution of early magmatic fluids with meteorite waters. Sr isotopic ratio of garnet vary between 0.70760 and 0.70805, suggesting that prominent role of the magmatic fluids for the formation of andraditic garnet.

The Darreh Amrood Pb (Ag) deposit is located in south of Ghohrood, in the Urumieh-Dokhtar magmatic arc (UDMA). Host rockes to the deposit are Middle to Late Eocene grey-green siliceous tuff and crystal lithic tuff. Geometry of orebodies is stratabound, irregular, and semiconcordant to discordant to layering of the host rocks. Ore structures and textures are dominated by semi-massive to brecciated, banded and vein-veinlets. Main primary minerals are galena, pyrite and chalcopyrite, and secondary minerals are dominated by covelline, goethite and hematite. Gangue minerals are epidote, chlorite, sericite, clay minerals, quartz, calcite and barite. Wall rock alterations are dominated by epidote-chlorite and sericitic. The rare earth element (REE) pattern of ores is not similar to that of volcanic rocks in the footwall and hangingwall that is concordant with sub-seafloor replacement process for ore formation. Also Ce showed negative anomaly that can be attributed to Ce in the seawater. Also based on structural, stratigraphic, petrographic, textures, mineralogical, alteration and geochemical studies, it is inferred that the Pb (Ag) mineralization in the Darreh Amrood area occurred as bimodal felsic- or Kuroko-type volcanogenic massive sulfide (VMS) mineralization, and formed as sub-seafloor replacement. It should be noted that the Darreh Amrood deposit is the first recognition of base metal-rich and poor barite VMS mineralization in the UDMA.

The Studied area is located in the small part of the structural zone of Urumieh- Dokhtar Magmatic Arc, at 60km far from south of Qom and 12km far from south east of Kahak. In the beginning, 1:25000 map of the area was prepared, because, region is located in two 1:100000 scale map sheet of Kahak and Aran, and more rock units were separated. In the next step, in a several step of the field observations, 17 samples of regional volcanic rocks were taken for XRF and ICP chemical analysis, and they main Oxides, heavy metals and rare elements were identife. Most of the samples have been located in the Calk- alkaline series, and some in the Tulleit series. In the lithology diagrams, these samples respectively are arranged in the range of Andesite, Dacite, Trachy Andesite and Rhyolite Rocks. Due to the anomalies and the amount of Nb in the samples of the region, they formation can be related to the subduction zone. On the other hand, the depletion of Nb and Ti is special in magmatism in the subduction zone. Because in the subduction regions released fluids from floating lithospheric rich in LILE, increases in the mantle wedge. Since in the study area rocks exhibit calc- alkaline with moderate to high potassium, it can be concluded that the stones are related to active continental margin associated with subduction.

The Aliabad area is located in the northwest of Nain. Volcanic rocks of the Aliabad area have andesitic to rhyolitic composition.On the basis of petrographic investigations, porphyritic texture is the main texture of these rocks. Thus, they have experienced two crystallization stages. In these rocks, phenocrysts have been crystallized in the first stage, and in the second stage the cooling processes were fast, resulting in a groundmass of glass and fine crystals.The second stage of crystallization in these rocks took place at (near) the earth surface. The composition of phenocrysts such as amphibole, biotite and pyroxene provide valuable data about magmatic series, pressure, and temperature history of the primary magma during crystallization. In this study, the clinopyroxene of these rocks was analyzed in order to estimate the physicochemical conditions of the parent magma.

Field work in the Aliabad area was carried out to identify volcanic units and their relationships. About 65 samples were collected. Thin sections were prepared for petrographic studies to select suitable samples of the volcanic rocks for more detailed mineralogical and geochemical studies. The chemical composition of minerals was determined using a wavelength dispersive EPMA (Cameca-SX 100) at Iran Minerals Research and Processing Center. Analytical conditions for the minerals were accelerating voltage of and a beam current of 15 nA. 15 kV.  Also, the Minpet software package was used for processing the relevant data and calculating the structural formula of clinopyroxene minerals based on 6 oxygen atoms.

The chemical compositions of clinopyroxenes were used to estimate the chemical evolution and P-T conditions of the magmas during crystallization. Microprobe analyses show that clinopyroxenes in the andesitic rocks are augite (En43-45Wo 38-42 Fs14-18).According to the clinopyroxene thrmobarometry calculations done by several methods, it was inferred that the clinopyroxenes are crystallized at temperatures of 1009-1200 °C and pressures of 2.5-7 kbar.By noting the distribution of aluminum in clinopyroxenes, these phenocrysts were formed in a range of low to medium pressure that shows the crystallization of those during the ascending of magma in different depths of 9 to 18 km. According to the Helz diagram (1973), the amount of water is about 10 percent. Clinopyroxene composition along petrographic investigations in the studied rocks confirm that ƒO2 is high.

The Aliabad area is located in the Urumieh- Dokhtar volcanoplutonic belt, Northwest of Nain- Iran. In the Aliabad area, the exposed Cenozoic volcanic rocks are compositionally from andesite to rhyolite. These rocks show porphyritic, trachytic, and amygdaloidal textures under the microscope and they consist of plagioclase, clinopyroxene, sanidine, quartz, opaque and apatite.The andesitic rocks of the Aliabad area are composed mainly of plagioclase and clinopyroxene phenocrysts in a groundmass of plagioclase microlites and fine crystals of pyroxene and opaque minerals along with glass. According to the ternary diagram of Wo-En-Fs (Morimoto, 1989), the studied clinopyroxenes are augite in composition. The physical (pressure and temperature) conditions of a magma during crystallization is recorded in the chemical composition of the clinopyroxene phenocrysts. Therefore, clinopyroxenes are representative of magma composition and usually are used for identifying the chemical condition i.e. magmatic series and physical conditions, temperature and pressure of a magma at the time when clinopyroxene was crystallized. Several methods that are applied for this purpose are as follows:1- The Soesoo (1997) method Based on this approach, the pressure and temperature formation of the Aliabad clinopyroxenes are about 3.5-6 kbar and 1150-1200 °C, respectively.2- The Sayari and Sharifi (2014) method According to this method, the pressure and temperature formation of the studied samples are about 2.48-4.8 kbar and 1074-1094 °C, respectively. 3- The Nimis and Taylor (2000) method Using this method, the temperature formation of clinopyroxenes in the Aliabad area is about 1009-1083 °C.

The authors of the manuscript would like to thank the respectable reviewers for valuable suggestions and also Dr. Sayari for his help in using the SCG software.

The North Narbaghi deposit is located approximately 26 km northeast of the city of Saveh in the central part of Urumieh-Dokhtar magmatic arc of Iran. In this area, the Oligo-Miocene intrusive rocks cut the Eocene volcano-sedimentary rocks intruding into the surrounding rocks causing extensive alteration zones such as phyllic, argillic, propylitic and tourmalinization. The intrusive rocks include diorite, monzodiorite, megadiorite with calc-alkaline nature which formed as a result of subduction of the Neo-Tethyan oceanic crust beneath the Central Iranian block. The epithermal Ag-Cu mineralization at North Narbaghi, with vein-veinlet and breccia geometries is mainly hosted in andesite, lithic tuff, diorite and monzodiorite. At the North Narbaghi deposit, ore minerals can be divided into four groups: sulfides (chalcopyrite, pyrite, sphalerite, bornite), sulfosalts (tetrahedrite, tennantite), carbonates (azurite, malachite) and oxides (hematite, goethite). The alteration shows a relative concentration pattern at the North Narbaghi deposit; the argillic, sericitic and calcite alteration types are in close connection with the Ag-Cu mineralization and the propylitic and tourmalinization alteration types occur at the margin of mineralization. The main characteristics of mineralization such as geodynamic environment, host rocks, mineralogy, metal content, geometry, alteration and comparing these features with the characteristics of epithermal deposits, show that the North Narbaghi deposit can be classified as a typical intermediate-sulfidation (IS) epithermal mineralization.

Clinopyroxene is one of the most common of the rock forming minerals. Its long formation period (from the earliest crystallization of magma in the core of phenocrysts to the final microcrystalline crystallization in the rock background) can show the history of the host magma crystallization. The composition of clinopyroxene, especially those phenocrysts, in volcanic rocks could well establish the magmatic nature of the host lava.The clinopyroxene composition can point out the magmatic series, the tectonic environment and the source rock (Kushiro, 1960; Nisbet and Pearce, 1977, Leterrier et al., 1982). In addition, it is possible to estimate the temperature and pressure of rock formation by studying the chemistry of clinopyroxenes (Nimis and Taylor, 2000; Putirka, 2008).The study area is located in the middle part of the Urumieh- Dokhtar magmatic belt. It exactly lies in the area between Tarq and Mazdeh, its longitude is 51° 43' to 52° 00' E and its latitude is 33° 15' to 33° 30' N. The Eocene magmatic rocks vary from rather basic to acidic in composition, but they are mainly intermediate and they are rather basic rocks (Ghadirpour, 2017). Previously, various studies on using the chemical composition of the major elements of clinopyroxene were conducted to discover the conditions for the formation of igneous rocks in different parts of Iran (Sayari and Sharifi, 2016; Falahaty et. al., 2016; and Mohammadi et. al., 2017).So far, in all of these studies that have been conducted on volcanic rocks, the mineral chemistry of clinopyroxene has not been used to evaluate the magma's features such as temperature, pressure, and oxygen fugacity. In this article, we are going to study the mentioned features of magma by using chinopyroxene chemistry. To determine the geotectonic setting and the physicochemical conditions of volcanic rocks, thirty thin sections have been prepared. Their minerals and texture have been studied by using polarizing binocular microscope (Olympus BH-2). After detailed mineralogy and selection of suitable samples, microprobe analysis is done by EPMA (JEOL- JXA) in the Naruto University, Japan. The mineral analysis is performed at 15 nA intensity of current and accelerate voltage of 15 Kev. The study area is situated in the South of Natanz, between Tarq and Mazdeh villages. The volcanic rocks vary from acidic to rather basic (basaltic andesite to andesite and rarely rhyolite). Microlitic porphyric, glomeroporphyric and vesicular are some textures which are observed in the volcanics. Plagioclase and euhedral clinopyroxene occasionally with simple twinning are characteristic minerals of rocks.According to Wo-En-Fs diagram (Morimoto, 1989), clinopyroxene shows mainly the composition of augite.It is concluded that the magmatic series of rocks is calc-alkaline which is in relation to the subduction of the Neotethys oceanic crust under the central Iranian plate.There are several diagrams that are used for this purpose which are as follows.The Al2O3-Ti2O diagram (Le Bas, 1962): In this diagram, the studied clinopyroxene shows the nature of calc-alkaline. One of the diagrams used to determine the tectonic setting according to clinopyroxene composition is the F1- F2 diagram (Nisbet and Pearce, 1977). Based on this diagram, the Tarq- Mazdeh volcanic rocks belong to the magmatic arc environment.The Clinopyroxene temperatures are calculated by using a variety of methods which indicate that most of clinopyroxene in temperature range of 1150 to 1200°C has been crystallized (Soesoo, 1997). The temperature indicates changes in crystallization of clinopyroxene. The calculated temperatures of clinopyroxenes by using various methods show that they are crystalized in the temperature range of 1150 to 1200˚c. It mainly means that there is a change in temperature during clinopyroxene crystallization. By considering the barometric diagram, the pressure of clinopyroxene formation has been determined below 10 kb, in the depth range of 2 to 5 km.

Abstract In the west and south-west part of Salafchegan near Zavarian village in Iran (In central Iranian volcano plotonic belt) there are some Plutonic rocks. Based on petrography and geochemistry findings these Plutonic rocks are Diorite, Monzonite and less Quartz monzonite. The main texture in Dioritic rocks is intergranular and in Monzonite is Porphyritic. Based on TAS diagram Samples located in Diorite, granodiorite and gabbrodiorite. Tectono-magmatic diagram Y Versus Zr shows the magmatic arc setting and Zr/TiO2 Versus Ce/P2O5 diagram contrasts postcolligenal magmatic arcs. Based on Chondrite and primitive mantle Spider diagrams, LREE have enriched to HREE in this area that makes the overal slope of these diagrams declined from left to right and this consident with the overal pattern of subduction zone. The results of petrography, geochemistry and tectonic setting studies in this area, indicate that neogene magmatism occurred in post colligenal tectonic setting - subduction of Neo-thetise ocean under central Iranian plate in neogen era.

Lale zar granite batolith is located in the southeast of Urumieh-Dokhtar magmatic belt and Dehech-Sarduieh. This mass includes a low density of tourmaline with nodule, vein and solar morphologies. Less tourmaline occurs in this mass could be due to mass being saturated in the boron. The studied tourmalines are classified in the shourl-dravite series and alkaline group. Most of the substitutions in these tourmalines are kinds: Ca + Mg (O) = Na + Mg (OH), Ca = X–vac + Na، Ca + Mg = (X-vac + Al) – 1 and Mg instead of Fe. Existence of clear zoonings in the tourmalines, large amounts of Mg and less than 0. 6 amounts of FeO / FeO + MgO, show the growth of tourmaline in the open systems where generated from magmatic-hydrothermal and hydrothermal. On the other hand, high amounts of REE elements and enrichment of LREE than HREE, enrichment of the transition elements such as Cr, V, Ni, Cu, Zn, Zr also can be show the hydrothermal origin for these tourmalines.

Natanz, 1:100000 geological map, is located in northeast Isfahan, in the Urumieh-Dokhtar structural zone. This sheet is a prospective area for Cu, Zn and Pb mineralization. Spatial distribution of geochemical anomalies for mineralization was identified; using pathfinder elements statistic method. The sample from catchment basin technique was applied on stream data. Then threshold elements were recognized and separated anomalies. The results show a good distribution of Pb, Zn, As and Sb elements close to copper index in the Natanz map. Moreover, fractal model used to introduce new anomalies in south portion of map for future exploration prospecting.