محمدولی ولی زاده

Most software produces models based on a pre-constructed grid. A grid network in 3-D modeling is an assemblage of voxels or cells of equal size. The number of cells producing is related to the spacing of the available data. The smaller the differences in the real data, the lower the dimensions of the cell unit, thus increasing the number of cells. The intersection of the lines formed by this network is called the node of the network and is calculated using the given data. These values are used for calculating each cell quantity and evaluating different cell values in the three-dimensional spaces. If one part is deleted based on operator order, the percent of remaining volume can easily be calculated by dividing the residual volume to total volume of the model. This study shows how to model spatial form and determine the quantity of mineral in the rock through the application of a small -scale high precision calculation. By paying attention to the used modeling method and using a high amount of data, the result will be as close as possible to the real distribution of minerals in the rock.In this research, to introduce the method and due to the full range of studies, the area 4 of metamorphism (Figure 1) Skarn Hassan Abad was selected for this research and was evaluated (mineralogy diversity is one of the essential reasons for this choice).Fig 1. Geological map of the studied area located in the south west of Yazd City.

In this study, serial section images are used for the modeling of the rocks. Five minerals (Clintonite, Diopside, Vesuvianite, garnet, and epidote) were selected and examined. The sampling is to cover all parts of the metamorphosed area and have a uniform distribution in the area, as well as all samples,  should be safe and identifiable and not be used for displaced specimens. Thirty-three samples were prepared according to the principles from different skarn ranges. At first, all specimens were cut in a few centimeters and then thin sections were prepared, and a fixed camera took a digital image of the surface on a polarizing microscope. A layer with one-centimeter thickness was removed, and the above procedure was repeated. Figure 2 shows images of serial sections of one rock samples.For total calculations and producing the network of image coordination, MATLAB software was used, and for final modeling, RockWorks software was used. Closest point method was used for modeling. In this method, each unknown point gets the value of the sharp boundaries (Wylie, 2005).Fig 2. Serial thin section of one studied samples (Xpl, Vesu: Vesuvianite).

Consequently, each image is identified by an m×n×3, matrix where m and n are length and width of the image respectively and dependent on the number of pixels per image. Numerical three is indicative of the red, green and blue colour bands. Matrixes of successive images are arranged as a column, and the Z value of each image in successive sections and the fourth value related to the numerical value of the green color was added. The final matrix with four columns X, Y, Z, and G is stored in a standard ASCII file. Finally, 33 models were prepared for 33 rock samples. The obtained models show a complete distribution of color band value for each mineral with the corresponding color scale. After calculating the statistical parameters, for each of the five minerals desired in all models, by the filtering, the amount of each mineral was determined. Other parts other than the minerals in question should be removed from the model, to do this. For this purpose, the normal distribution curve of the prepared models was used. According to the desired tables, depending on the increase or decrease of selected minerals in all profiles, it is possible to determine the zoning of minerals around the intrusive rock accurately.For other minerals, these values are calculated and listed separately in the tables, and due to the amounts obtained from this mineral and the presence or absence of specific skarner minerals, the conditions of temperature and pressure governing the metamorphic region with a higher probability of Measurement. The normal distribution curve for each reaction zone (skarn zone) is shown on average from all four zones in Fig. 3. According to the volumetric tables of 5 minerals selected, the total amount of garnet, diopside, vesuvianite, clintonite and epidote minerals is 58.77%. As a result, the remaining volumetric percentages are (according to microscopic examination and XRD tests, these minerals have been confirmed in the region): apatite, quartz, low thermolite, wollastonite, significant calcite, and metal ores. These turning points coincide with the “average ± standard deviation” on the normal distribution curve. In this study, all models were filtered based on the two numbers average ± standard deviation. Since the rock matrix volume is always more extensive than that of the mineral, distribution values around the average ± standard deviation of the data reflect the values related to the rock. Mineral amounts can be obtained by subtracting these amounts from the total population of the model (Fig.4). The relative amount of minerals in the rock can be obtained by dividing volume of the mineral in the rock to the volume of the rock. Equation (1) shows the percentage of mineral in the rock. 
   (1)
Where FMV is the volume of filtered model (volume of minerals) and MV is total volume of model.
 
Fig 3. The mean distribution curve for the normal distribution is in the range of 105 meters (1); 105-222 meters (2); 222-320 meters (3); 320-450 meters (4).
 
Fig 4. Filtered models of the minerals.
 Conclusions

Calculating mineral quantities and the determination of the three-dimensional distribution of minerals is necessary for the petrological and economic geology investigations. The total volumes of 5 selected minerals are 58.77%. As a result, the remaining volumetric percentages are Apatite, quartz, thermolite in a small amount; Wollastonite and calcite significantly and metallic minerals.By extensive sampling of ores in different areas, it is possible to use this method in ore body volume determination. Also, this method has many applications such as studying of the fluid inclusions, calculation of the type, and amount of porosity in oil reservoirs and studying the tectonic of the selected area.

The Shah-Kuh granitoid has intruded in the Triassic–Jurassic، pelitic and psammitic low grade metamorphic rocks of the NE Lut Block، in Central Iran. Cordierite porphyroblasts are common in the southern pelitic sediments، but are rare in the northern psammitic rocks، in the contact aureole. Deformation fabrics in the contact aureole are well preserved within the cordierite porphyroblasts. The relation of the cordierite porphyroblasts and deformation fabrics indicate that the time of growth has started and is synchronous with the first deformation phase and ends after the second deformation stage. The porphyroblasts are also generated in syn-intrusion ductile shear zones existing in the contact aureole and continue inside the Shah-Kuh granitoid. Shear zones in the contact aureole contain deformed cordierite porphyroblasts، with microstructures indicating clear shear sense. Structural analysis of various metamorphic rocks in the contact aureole of the Shah-kuh granitoid indicates a first stage، which is tight to the isoclinal folds، with well-developed axialplane foliation، and a second stage of crenulation cleavage. Sequential growth of cordierite porphyroblasts preserved fabric from various stages of a progressive deformation in the granite contact aureole. It is concluded that the Shah-Kuh granitoid has intrusions synchronous with progressive deformation، cordierite porphyroblasts growth، and shear zone development in the contact aureole of the granitoid.

The Dehnow area is located in the northwest of Mashhad city and in the structural zone of Binalood, along the east Alborz range. The major rock units in the study area include tonalite (to diorite and granodiorite), hornfels and surrounding schist. The regional metamorphism that produced the schists occurred in Triassic, while the granitoids intruded in them during Upper Triassic, a thin layer of hornfels (~ 200m) has occurred in the intrusion, and schists contact. The Dehnow plutonic rocks, hornfels and schist contain garnet as an accessory mineral. In this work, diffusion effect of Fe, Mn, Mg and Ca in the garnet was studied. According to the geochemical data, low content of Ca in the garnet rim, falling trend of Fe from core to rim, low diffusion rates of these elements and the large size of garnets indicate that the garnets within tonalite are not distinctly affected by diffusion of these elements, but their elemental variation is resulted mostly by the chemical evolution of the melt from which they crystallized. In addition, erratic trends of Fe and Mn and the constant Ca and Mg trends from core to rim of garnets within the schist and hornfels, and also the low temperature of crystallization and the short time of garnets growth in these rocks show that diffusion effects on these garnets growth is negligible.

The Aligoudarz granitoid occurs in the central part of the Sanandaj-Sirjan Zone, western Iran. It comprises three distinct facies mainly of tonalite, granodiorite and granite composition. Magmatic microgranular enclaves (ME) extensively occur in granodiorite. Field, textural, whole rock and mineral chemistry data of the ME and the host rocks does not support magma mixing as the ME-forming mechanism. Major and trace elements variation diagrams, similarities in spider diagrams and geochemical modeling indicate the cogenetic relation of the ME and host rock. Fractional crystallization is the main process in the geneses of ME. Rapidly-cooled borders of the magma chamber can best explain formation of the ME. ME are the result of later fragmentation and dispersal of the rapidly-cooled borders in the host magma. These enclaves recorded the least degree of chemical exchange with the host. Biotite and amphibole crystallize with more rapid nucleation rates in rapid cooling zones. This process can explain different chemical behavior of the ME and the host rock.

Metamorphic rocks of Dehnow area mainly consist of gray to black fine-grained schists. Garnet schists are closer to the tonalitic body than the garnet chloritoid schists. There is a thin layer of staurolite and andalusite bearing hornfels between these schists and the Dehnow tonalitic body. Garnet schists and garnet chloritoid schists of Dehnow area are mineralogically comprised of quartz, biotite, muscovite, garnet, chlorite, chloritoid, tourmaline and ilmenite. Geothermobarometry results indicate that hornfels (550oC, 4.3 kbar) and garnet chloritoid schist (486-497oC) have formed in lower equilibrium condition in comparison with garnet schist (569oC, 5.3 kbar).

Granitic rocks of Malayer plutonic complex contain varieties of enclaves with different shapes, sizes, mineralogy and chemical composition. The interpretation of bivariant geochemical diagrams of major oxides and trace elements with respect to higher values of some of oxides such as MnO, TiO2, MgO, CaO & FeOt than host rocks in one groups of enclaves and moreover linear trend of these oxides and some of trace elements such as Ni, Cr, V indicate to different nature and mafic source of these enclaves (Mafic type) than host rocks and other enclaves (Felsic type).The study of chemical composition of this enclaves by using of univariant and bivariant statistical methods (bivariant regression analysis, correlation coefficients, cluster analysis and principle component analysis) indicate clear chemical contrast between mafic enclaves with felsic enclaves and granitic host rocks and in other side chemical affinity of felsic enclaves and their host rocks. Distinctive distribution of the majority of oxides and trace elements of mafic enclaves and host rocks and low values for R2 in regression analysis, low value of correlation coefficient of major element oxides and trace elements between enclaves and their host rocks, separate position of samples in cluster pattern and special direction of variants and samples of vectors in bivariant diagram of principle component analysis (PCA) are outputs of different geochemical characteristics of enclaves and host rocks. Moreover this correlates with different trends of each major oxides and trace elements in bivariant geochemical diagram (Harker diagram).

The Aligoodarz granitoid occurs in Sanandaj-Sirjan Zone (SSZ), Western Iran. Tonalite, granodiorite and granite are the main rock types cropping out in the area. Comparison of Aligoodarz granitoid with Dehno and Boroujerd granitoids reveals several similarities in their chemical characteristics. Thus, the above mentioned granitoids can be assigned as a co-genetic magmatic suite, in which plutons evolved from a parental magma; with fractional crystallization being the main mechanism for magma evolution. Samples with lower SiO2 content from different areas, are not similar in composition, and indicating varying degrees of mineral accumulation and trapped interstitial melts. These granitoids are compositionally similar to normal I-type granitoid rocks originated from continental arcs. Compared with the primordial mantle, they are enriched in Large Ion Lithophile Elements (LILE) and Light Rare Earth Elements (LREE) over High Field Strength Elements (HFSE) and Heavy Rare Earth Elements (HREE). This feature together with relative depletion of Ta, Nb, Ti, and P confirm derivation of these granitoids from a crustal source region in continental arc environment

In the west and north west of Hassan-Abaad village of Yazd, massive dikes of alkali andesite in the diorite, quartz diorite and granodiorite are observed. Clinopyroxene phenocrysts in these rocks have obvious zoning. Reconnaissance work indicates that groundmass pyroxenes in the alkaline rocks are similar to the more evolved phenocryst rims. Obtained data from core to rim of Clinopyroxene phenocrysts by SEM point analysis, show that Clinopyroxene composition, contains Chrome-diopsides, Salites-ferrosalites and Titanaugite. Clinopyroxene zoning formed during crystal growth. These pyroxenes are believed to record an intricate history of stop-start differentiation, magma-mixing, entry or disappearance of high-pressure precipitates. The salitic and ferrosalitic crystals of the Hassan-Abaad andesite also represent accidental fragments of anomalous upper mantle wall rocks.

The results of field studies (i.e. shape, dimensions, spatial distribution, condition of enclaves and xenoliths in the host rocks at available outcrops) experimental observations (i.e. petrographical and microstructural study of enclaves and xenoliths and whole rock geochemistry of magmatic encalves) show that magmatic enclaves are mafic and felsic types, while xenoliths are hornfelsic. Elongation of magmatic enclaves and hornfelsic xenoliths along their apparent longitude axis in the margin of intrusive body are attributed to influence of stress on enclaves in melt or semi-solid phases and xenoliths in plastic form. In addition, this is related to impact of high force of magmatic flow in contact with metamorphic wall rocks. This indicates that the origin of xenoliths is the metamorphic rocks which lie at the periphery of the intrusive body. Existing of aligned mafic enclaves in the host, in addition to, presence of signs of plastic deformations (in microscopic scale) in micro-scale fluid features can be attributed to superimposition of solid-state deformation on magmatic flow. Due to lack of solid-state plastic deformation evidences, applicability of magmatic flow criteria and distinguishable interface of magmatic enclaves with host rocks in microscopic and macroscopic scales, spherical, globular, ellipsoidal and spindle shapes of mafic magmatic enclaves attributed to presence of theirs as mafic globule and packets in the host felsic magma, and also their similarity in superficial appearance, textural, mineralogy and geochemistry with the host rock, attributed to their different origin and magma mixing event. The formation of irregular shaped magmatic felsic enclaves with recognizable mineralogical and geochemical similarity to the host rocks, which are observed at the periphery or ceiling of the plutons, related to peripheral interruption in the primary phase of magmatic injection caused by the high pressure of consecutive injection pulse and replacement of new magmatic charge.

The crystallization history of a rock is recorded by the size and the distribution of its minerals. The porphyroblast crystal size in metamorphic rocks can give notable information about its growing medium. Considering the varieties of mineralogy in the Hassan-Abad''s skarn and high frequency of garnet porphyroblasts in different metamorphic zones and special different sizes in the first metamorphic zone of the NE skarn، the crystal size distributions of this mineral is studied. With regard to this، digital photos of cutting surface were provided and analyzed by JMicrovision software. It has been expected، two different slopes can show three suspections: 1- parent rock composition effect; 2- crystal growing time; 3- fluid flow around plutonic rock. According to the presence of clintonite، vesuvianite and garnet and as many as joints in the region، the role of fluid in growing the size of garnet porphyroblast in part of the first metamorphic zone seem to be noticeable.

The Astaneh granitoid massif is located about 40 km to Arak city, central Iran, is a part of Sanandaj-Sirjan structural Zone. These intrusive rocks which are mainly composed of grnodioritic rocks, widely affected under hydrothermal alteration. The alteration zones, on the basis of field studies and mineralogy as well as the study of the REE behavior, are investigated in this paper. Eight alteration zones including phyllic (sericitic) with quartz, sericite and pyrite; chloritic with quartz, sericite and chlorite; propylitic with chlorite, epidot, calcite and albite; argillic with clay minerals (chlorite and illite); silicic with abundant quartz; albitic with albite, chlorite and quartz; hematitisation with hematite, Fe-carbonates (ankerite and siderite) and tourmalinisation with tourmaline (dravite) are identified. The results demonstrate notable differences in the REE behavior in the different alteration zones. Accordingly, comparison with the fresh rocks, in the phyllic (sericitic) alteration, LREE are enriched, but HREE, except Yb which enriched, unchanged. Also in chloritic alteration zone, LREEs are depleted, but HREEs represent different behaviors. In the argillic and propylitic alteration zones, all REE are depleted, but compared with HREE, the LREE represent more depletion. In the silicic and hematitisation alteration zones, compared with HREE, the LREE are enriched. Finally, in the albitic and tourmalinisation alteration zones all REE are depleted. These features indicate that the behavior of REE in the hydrothermal alteration zones of the Astaneh granitoid rocks is mainly controlled by PH, availability of complexing ions in the fluid as well as the presence of secondary phases as host REE minerals.

The determination of mineral quantities is one of the primary purposes of petrology and economic geology studies. When producing skarn zonation, it is necessary for the quantities of minerals in each zone to be known. Currently, various methods of determination for mineral quantities in rock bodies have been developed, but a rapid, accurate and economic method for distinguishing 3D mineral distribution has not yet been understood. This study introduces such a method for distinguishing 3D mineral distribution based on image sequence modelling of rocks. In the studied area, -Hassan-Abaad of Taft, central Iran- garnet is one of the most important and most frequent minerals found in skarns and is present in a variety of types and places. For our study, we sampled a very thin layer of rock (300 microns) and prepared a digital photo at every stage of our analysis. Prepared images were analyzed using MATLAB software. Each value of the image with its x, y and z coordinates was stored in a new matrix. Matrices were modelled in RockWorks and filtered based on the mean standard deviation of the modelled data, producing garnet networks. The studied zone had 31.4% garnet, allowing to be considered a garnet- wollastonite zone. This method is also useful for different calculations, such as: determining rock type, field zonation, calculation of the amount of mine and waste material, fluid inclusion studies and distinguishing type and volume of rock porosity.

Malayer granitoid rocks, as a part of Sanandaj-Sirjan plutonism, are located at latitude 34°00´-34°18´ and longitude 48°30´-48°52´. Tectono-‌‌magmatic investigation on the history of Sanandaj-Sirjan Zone attributed the formation of these plutonic rocks to convergence of Iranian and Arabian plates in conjunction with subduction of Neo-Tethys in the western part of Sanandaj-Sirjan Zone. Geochemical studies of Major and Trace elements on Malayer granitic rocks reveal that these granitic plutons are formed in a compressive environment, such as active continental margin in the convergent zone of oceanic crust and continental plate at the magmatic arc of continental margin. High ratio of LILEs/HFSEs and negative anomaly of Sr, Nb, Ba and Ta confirm the relation of these granitoids to subduction zone. These, also point out the role of shallow continental crust in formation and evolution of granitoidic magma. Broad range of mineral composition in petrographical observations and large variations in field studies, high-K calc-alkaline affinity and assessment of trends observed in AFM, K2O-SiO2, FeO-MgO diagrams versus those of plutons of known tectonic setting accentuate the similarities between Malayer granitic rocks and Andian type Magmatic Arc of Active Continental Margins and as a result highlights the role of upper mantle mafic magmas and tectonic movement in formation of their parental magma.

-Abaad skarn centeral Iran, is studied to better understand the evolution of the skarn. Trioctahedral, Ca-mica occurs locally in aluminous contact marbles around Hassan-Abaad granitoid stock. Rare clintonite-Na margarite solid solution have been observed, where margarite itself formed after plagioclase. Coexisting mineral phases are calcite, clinopyroxene, spinel, garnet, forstrite, vesuvianite, wollastonite. Tow reaction between the observed phases result in clintonite formation in this zone (Fo + Cpx + Cc + Sp + H2O = Cli + CO2 and Cpx + Cc + Sp + H2O = Cli + Fo + CO2). Phase relations restricts the stability field of clintonite to relatively low chemical potential of CO2 and/ or high chemical potential of H2O. Generation of clintonite is probably related to circulation of F-rich fluids through carbonate bodies. The main source for F is introusive plutonic and relaeted hydrothermal fluid. plagioclase breakdown to margarite can explain deplation of Na2O, K2O and SiO2.The model of clintonite formation and evolution of Hassan-Abaad skarn is that the mineral assemblage in this area is experienced crystallization in an open system with F flow in releation with crystallization in a close system. In this area clintonite is formed between 620-650?C.

The intrusive bodies of Central Alborz constiute speciale distribution. And they are located near major faults, and also they are accompnied by pyroclastic rocks of the Karaj Formation.Moreover they display lithological diversity and they occur as sill, lopolith, stock and plug. These intrusive bodies blong to post upper Eocene and they are related to the Pyrenean- equivalent orogenic phase. Rregarding the geochemical results obtained by other researchers, as well as determining the nomenclature, definiton of granitoid and gabbroic bodies the composition of the above mentioned masses, fall within the calc - alkaline to alcaline range. However, most specimens are plotted in the field of type I granitoids.From the tectonic viewpoint, all of the intrusive bodies are Considered as syntectonic. Moreover, they are often of continental subduction Zone(CAG)origin, while other may be long to continental collision type(CCG), and a few are located to the island arcs(IAG).

Zahedan granitoidic pluton with general NW-SE elongation is located in the middle part of the Zahedan-Saravan granitoidic belt. It includes granites, granodiorites and diorites and it is also cut by numerous of andesitic to dacitic dikes. The regional metamorphic rocks of the area, with the age of Eocene, have been intruded by this pluton. In this research, emplacement mechanism of the northern part of Zahedan pluton has been studied with the aid of anisotropy of magnetic susceptibility (AMS) method. The results show that granitic rocks of the Zahedan pluton belong to paramagenitic granites (µSI) while diorites and granodiorites belong to ferromagentic granites (µSI). The magnetic lineations and foliations of the pluton mainly have low dip or sub-horizontal. In contrast, dioritic rocks which cover a small area, have magnetic lineations and foliations with high dip (sub-vertical). Therefore, dioritic rocks are considered as the feeder zone or the ascent location of the magma for this part of the Zahedan granitoidic pluton. Very low dip magnetic lineations and foliations suggest that Zahedan granitoidic pluton has been emplaced as sill. The activity of a very low dip simple shear movement has an important role in preparing a suitable space for emplacement of this granitoidic pluton.

The crystal-chemistry of the plagioclase, alkali feldspar, biotite, amphibole and whole rock geochemistry of Akapol granitic massif are investigated in this paper. The chemical composition of biotites and amphiboles ploted in the annite-siderophyllite, magnesiohornblende and actinolite fields, respectively. Comparison of the chemical composition of biotites and amphiboles with similar minerals from the California granitic batholith indicate that the monzogranitic unit of Akapol belongs to the strongly contaminated I-type granites. Accordingly, these rocks are highly contaminated and may have derived from upper mantle and/or lower crustal sources. They have experienced magma mixing or are affected by contamination with upper crustal rocks. These results are consistent with the curve like logarithmic diagrams of compatible/incompatible elements; the presence of the sieve, poikilitic and rapakivi textures; the partial absorption of the plagioclase phenocherists; the presence of mafic microgranular enclaves and needle apatite in the samples. Based on this study, two types of plagioclase in monzogranitic unit can be recognized in the monzogranitic unit: the first generation occur in the alkali feldspar phenochrysts and the second generation is in the form of covering crystals in rapakivi and sieve textures which probably formed during magma mixing.

Boroujerd granitoid mass belongs to Sanandaj – Sirjan zone (SSZ). It consists of granodiorites, quartz diorites and monzogranites. The country rocks into which the Boroujerd granitoid was emplaced consist of greenschist rocks of the regional metamorphism.The statistical technique of discriminant analysis, using major element differences alone, shows that this mass has characteristics of orogenic granitoids (R>0). The Boroujerd granitoid has geochemical characteristics typical of arc intrusives e.g. I-type, high-K calc-alkaline series, metaluminous to weakly peraluminous, a greater enrichment in LILEs (Cs, K, Rb, U, Th) compared to HFSEs (Nb, Ta), depletion in Sr, Ba, P and Ti relative to other trace elements. High Th/Yb (>5) ratios correlated to high values (>10, up to ca. 100) for La/Yb and plot as volcanic arc granites on various discriminant diagrams. This granitoid is a typical representative of a volcanic arc environment, spatially related to an active continental margin. Crustal contamination processes provide a further complication in the interpretation of the Boroujerd rocks. The rarity of primitive magma compositions in arcs, particularly continental margin arcs, points to the important and consistent role of such processes. Probably, Boroujerd granitoid is the result of the subduction of Neo- Tethyan oceanic plate below the Iranian microcontinent.

Igneous rocks of the Karaj Dam basement are mainly composed of gabbro, diorite and monzodiorite-monzonite which are locally penetrated by the quartz-monzonitic dikes. The upper and lower margins of the pluton, which has gabbroic composition, show porphyritic texture (chilled margin). The porphyritic texture in chilled margin gradually changes to the equigranular gabbro, diorite and monzodiorite-monzonite. The mineral chemistry (electron microprobe analysis) of the plagioclase and pyroxene in various rock samples from lower contact chilled towards the upper parts suggesting differentiation processes. The Mg of the pyroxene and An% of plagioclase of the contact chilled samples can be used as an indication of the original magma and plotted between the gabbro and monzonitic samples. In addition, increasing of the Mg within the whole rock samples from the upper of contact chilled, in comparison to the lower one, suggests elements differentiation by the gravity diffusion. Moreover, Na2O, K2O and incompatible elements increase and MgO, Fe2O3 (tot), CaO and compatible elements decrease with the progress of the magma differentiation. The samples in the Log Ni-Log La and Log Ni-Log Zr diagram plot almost as straight horizontal line, which confirms occurrence of the magma differentiation.

Arash Syenite is located in central Iran and in Bafq metalogenic province, and has intruded into the Precambrian-Cambrian volcanic-sedimentary sequences. Size and distribution of minerals are not uniform in all parts of the body and vary from chilled margins to the central part of the pluton. Effects of tectonic movements, existence of uncommon textures in plagioclase crystals and the appearance of metasomatic textures are the main evidence for metasomatism. Study of elemental concentration deduced from mass balance calculation reveals the effects of alkaline metasomatism in Arash Syenite. Gain in K2O (and Rb) and Al2O3 with parallel losses in Fe2O3, CaO, Na2O, Ba and Sr are shown. Relative increase in Nb and Zr are due to leaching of mobile cations in this pluton.Decrease in Zr and Nb with parallel increase in SiO2, which is one of the most identical factors for the calc-alkaline differentiation, is remarkable in Arash Syenite. There is a clear change in Y, Th and Nb relative to Zr in this pluton and based on the constant ratio of Zr/Nb, the role of contamination and assimilation of country rock is insignificant in the pertrogenesis of this pluton. Negative anomaly for Nb and TiO2 suggest a subduction-related origin for the Arash Syenite.