جستجوی مقالات مرتبط با کلیدواژه « شیمی کانی » در نشریات گروه « زمین شناسی »

Ophiolites are slices of oceanic lithosphere obducted onto a continental margin and can be classified as mid-oceanic ridge (MOR) or suprasubduction zone (SSZ) types based on the tectonic setting in which they originally formed (Pearce et al., 2000; Shervais, 2001). The Zagros Orogen extends from eastern Turkey through northern Iraq and northwest of Iran to the Hormuz Strait and Oman (Alavi 1994; McQuarrie, 2003; Homke et al., 2004; Agard et al., 2005; Shafaii Moghadam et al., 2018). The geodynamic evolution of the Zagros Belt is mainly related to the opening and closure of the Neo-Tethys oceanic basin. Ophiolites, as Neotethys oceanic lithosphere remnants, are emplaced along the Zagros Orogen. These ophiolites are emplaced along two main belts (Saccani et al., 2013; Shafaii Moghadam et al., 2018). The Neo-Tethys suture zone coincides with the Main Zagros thrust fault (Agard et al., 2005) and ophiolites are exposed scattered along this zone. 

The Dalampar ophiolite, located between the Piranshahr and Salmas ophiolites. The Dalampar ophiolites consist mainly of strongly sheared serpentinized ultramafic rocks including harzburgite, dunite overlaid by gabbro and basalt units. The emplacement mechanism of the Dalampar ophiolite massifs into the Iranian microcontinent and structural evolution is completely unknown. There has been not performed a systematic investigation of these ophiolites and geodynamic and relation with other ophiolites are not well Studied.
Thus, the main purpose of the present paper is to investigate the petrogenetic processes, tectono-magmatic environment, using mineral chemistry and textural evidences of Dalampar ophiolite which are fundamental for understanding the tectonic evolution of the Neo-Tethyan Ocean.

During the fieldwork, a number of suitable peridotites samples with least alteration effects were selected. Folloing the petrographic studies, a thin polished section was prepared from several harzburgites for microprobe analysis using JEOL JXA-8600 M model,15 kv accelerator voltage and 2-ray current 10-8 Amp, placed at the Department of Earth Sciences and Environment of Yamagata University, Japan.

Harzburgites are the most basic and widespread ultramafic units in Dalampar ophiolite complex. They show evidences including the presence of exsolution of clinopyroxene in orthopyroxene, the orientation and elongation of the crystals indicating these rocks were formed in the upper mantle conditions and reached equilibrium in the crustal environment. Exsolutions of clinopyroxene lamellae from orthopyroxene are one of the textures observed in the rocks under study and is widespread in both abyssal and SSZ peridotites (Tamura and Arai, 2006). The Cr# of spinel in abyssal peridotites is a good indicator of the degree of partial melting for the mantle-derived spinel peridotite. Low Cr# spinels represent less depleted peridotites, whereas the high Cr# spinels highlight more depleted peridotites (Dick and Bullen, 1984; Arai, 1994). in the Mid-oceanic ridges, the degrees of partial melting and depletion are generally low. In contrast, the supra-subduction zone peridotites have a high degree of partial melting and depletion (Niu and Hekinian, 1997). The content of Cr# in presented Cr-spinels are high (78-83%), and associated with boninitic melts formed by high degrees of partial melting or much more extensive melt-rock reaction (Arai, 1994). As the the Cr# of spinel versus the Fo content of olivine diagram shows the harzburgites fall in SSZ domain. Furthermore, all rock types fall into olivine-spinel mantle array (OSMA). This is regarded as the evidence for their residual origin, i.e. they form a trend which was likely caused by partial melting. Experimental studies confirm that the Al2O3 and TiO2 contents, as well as FeO/MgO ratios in chromian spinel are directly related to those of the parental melt (Rollinson, 2008). According to Maurel and Maurel (1982), The Al2O3 contents of the parental melt range from 10 to 11 wt. % for the studied Harzburgites. Such values are consistent with boninitic melts, which typically contain 10–14 wt.%, respectively (Dilek and Thy, 2009). In the Cr# versus TiO2 diagram, the Dalampar peridotites classify as depleted peridotites. In consequence, chemistry of the chromian spinels in the Dalampar peridotites are compatible with a genesis in a suprasubduction zone from boninitic or primitive arc magmas. However, forearc regions may contain both SSZ and abyssal peridotites, although the former are typically dominant (Pearce et al., 2000). Olivine-spinel and orthopyroxene-clinopyroxene thermobarometry in the harzburgites shows equilibrium temperatures of 1000-1100 ºC at a pressure of 28 kbar and suggests that they have been equilibrated in spinel peridotite field.

The Dalampar Ophiolitic Complex as a part of the Tethyan ophiolites is exposed in the northwestern part of the Iranian-Azerbaijan province, extending to the Anatolian ophiolites in southeastern Turkey. The petrography, geochemistry and microstructural studies of the residual mantle sequence in Dalampar Ophiolitic Complex provide important information regarding the degree of partial melting and deformation in the oceanic mantle lithosphere. Mineral chemistry clearly indicate that Dalampar ultramafic rocks record an episode of boninitic magmatism occurred within the southern Neo-Tethys Ocean in the Late Cretaceous. Boninitic melts in Dalampar Ophiolites were formed by partial melting of depleted peridotite, a residue after MORB-type melt extraction. Mineral chemical data indicate that SSZ peridotites are the residues from ∼30–40% of mantle melting. Nonetheless, the very low (< 0.25 wt. %) TiO2 calculated for the parental melt in equilibrium with chromian spinel are only consistent with boninitic-type parental melts. Based on geothermobarometry calibration the temperature and pressure of crystallization of harzburgite rocks were 1000 to 1200 ° C and 24 Kbar, corresponding to the SSZ tectonic environment.

The kalasur_Kharil granitoid complex with Oligocene age, is located in SW Kaleybar of NW Iran, Alborz-Azarbaijan zone. The rocks are intruded into the Cretaceous volcanic and sedimentary rocks. The composition of plutonic rocks are consist of gabbro-diorite, diorite, quartz monzodiorite and granite. The major minerals in gabbro-dioritic and dioritic rocks are plagioclase, clinopyroxene, amphibole, biotite and major minerals in quartz monzodioritic and granitic rocks are potassium feldspar, plagioclase, quartz, amphibole and biotite. On the basis of mineral chemistry, the composition of clinopyroxenes is in diopside range. Amphibole minerals are calcic in study area. The calcic amphiboles indicates that the rocks of the studied area belong to type I granitoids. The Khari- Kalasour amphiboles are magnesio hornblende. The biotite in Kharil- Kalasur granite with Fe/(Fe+Mg)>3 is magnesio-biotite. The feldspar composition is albite-andesine in granite, labradorite, andsine and orthoclase in dioritic and quartz monzodioritic rocks. Mineral chemistry of the biotite, amphiboles and pyroxenes indicate that this rocks are calc-alkaline and have been crystallized in a subduction zone setting.

The granitoides of west Ardakan are outcropped in the middle part of the Central Iran zone. Quartz, orthoclase and plagioclase are the main minerals and amphibole, biotite, sphene, zircon and apatite are secondary minerals. The dominant textures are medium to fine grain granular, granophyry and myrmikite[r1] . According to mineral chemistry data, calcic amphiboles of magnesiohornblende to actinolite nature have crystallized at temperatures of 530-890 ºC. Oligoclase to andesine plagioclased crystallized at 700-800 ºC. Magnesium biotites was crystallized at 650-730 ºC. On the basis of the oxidant conditions, magnetite are formed as opaque. The chemical analysis of all these minerals show the mantle nature of the magma. Magma seems to suffer produced these minerals, moderate to severe crustal contamination during its ascent. These granitoides are I type and calc-alkaline and were formed in the subduction setting related to the active continental margin.

The South-Gharezagh intrusive exposed in northwest of the Sorsat metamorphic complex, which is structurally a part of the Sanandaj-Sirjan zone. Intrusive of South-Gharezagh is located in the shear zone and are mylonitized. Morphologically, the crystallization of zircon in the intrusive and mylonitic mass of South-Gharezagh includes {110} prisms and {211} pyramids, which indicates their crystallization from S-type magmas. The crystallization temperature is calculated to be 698 to 770 ◦C, based on the morphology of zircon, in the massive and mylonitic parts of the South-Gharezagh massif, zircon saturation thermometry and geochemistry of the whole rock. In addition, the thermobarometric chemistry of biotite mineral has been calculated at a temperature of 677 ◦C and a pressure of 0.8 kbar. The petrofabric evidence shows that chemical and petrofabric changes have been gradually occurred along with the deformation progress in mylonites. As a result of petrofabric, the recrystallized quartz grains and the migration of the grain boundary in the recrystallization is clear, which indicates a change in the facies of the green schist metamorphism.

Metamorphic rocks in the Faryab complex are part of the Bajgan metamorphic complex with Upper Cretaceous age that crops out in the southeast of Sanandaj-Sirjan zone, south Iran. The metamorphic rocks of Faryab Complex have been metamorphosed in greenschist and amphibolite facies include garnet mica schist, epidote schist, epidote amphibole schist, amphibole schist, epidote amphibolite, amphibolite and garnet amphibolite. Minerals composing amphibolites are garnet, amphibole, epidote, plagioclase, quartz, chlorite and sphene as well as titanite and magnetite as secondary minerals. The composition of amphiboles in amphibolite and epidote amphibolite are made of calcic types and their chemistry varies from magnesio-hornblende through ferro-tschermakite-hornblende, ferro paragasite-hornblende, ferro edenite-hornblende to ferroedenite. The composition of plagioclas ranges from albite to oligoclase. The protolith of most amphibolites and epidote amphibolites in the Faryab complex are defined by the occurrence of key minerals in metabasites and are considered as basalt and gabbro. Several thermobarometeric calculation methods indicate that the highest temperature and pressure for the amphibolites, which were appeared adjacent to peridotites and located in the northern part of the complex, are about 700 °C and 9.7 kbar. By moving away from the peridotites into the lower structural units in the southern part of the Faryab complex, the temperature and pressure range in the amphibolite and epidote amphibolite and decrease to 510°C and 4.34 kbar on average, which is beginning of amphibolite and middle amphibolite facies. Investigation of the P-T pathes in conjunction with close associations of isograde lines show that geothermal gradients were high even at the beginning of metamorphism. Mineral chemistry and thermobarometric calculations along with consideration of the structural position of the Faryab complex indicate that the tectonic position of the Faryab complex in the Sanandaj-Sirjan zone may remined us an accretion-subduction complex. This complex was constructed in the north-dipping Neo-Tethyan subduction zone during the Late Cretaceous time, which caused the higher degree metamorphic rocks were thrusted onto the shallower ones.

Tourmaline is a borosilicate mineral with general formula of XY3Z6[T6O18](BO3)3V3W. Experimental studies demonstrate a wide range of stability for tourmaline-supergroup minerals to record different geological processes. They occur in metamorphic, granitic pegmatites, and clastic sedimentary rocks and are associated with hydrothermal activities (Dutrow and Henry, 2011; Slack and Trumbull, 2011). Textural and compositional features of tourmaline can be used as an indicator of environment in which it crystallized. Tourmaline from porphyry deposits generally show a. frequently crystal zoning, b. development from Fe-rich to Mg-rich, and c. total Mg content is ~2 apfu in copper deposits and 1-2 apfu in Au deposits (Baksheev et al., 2012). It is believed that the world-class Dashkasan gold deposit records the transformation of porphyry to low-sulfide epithermal (Richards et al., 2006). The Dashkasan gold deposit located in the Kurdistan Province can be a significant region for better understanding the origin and the evolution of ore-forming fluids using chemistry of tourmaline. For the present study, we also tried to apply fluid inclusions data on quartz-tourmaline-pyrite veins from the Dashkasan deposit.

Polished-thin sections of various tourmalines of the Dashkasan deposit were examined using a Cameca SX100 Electron Probe Micro Analysis (EPMA) at the Iran Mineral Processing Research Center, Karaj. Fluid inclusion studies were performed on quartz crystals of quartz-tourmaline-pyrite veins. The microthermometric parametes of fluid inclsions were measured by Linkam-THMS-600 stage at the University of Isfahan.

The Dashkasan gold deposit with 52 Mt of oxidized ore and average grades of 1.77 g/t Au is hosted by the Middle-Miocene porphyritic dacite/rhyodacite and dacitic breccia rocks. The main minerals are quartz, K-feldspar, hornblende and biotite mainly altered.. This deposit is characterized by the transition from the porphyry to the epidermal system with the presence of tourmaline minerals in phyllic and silicification alteration associated with gold veins. As petrographic examination shows tourmaline occurs as disseminated, vein/veinlet, and breccia textures in three types: Tur-1 occurred as needle shape in dacitic rocks associated with phyllic alteration; Tur-2 crystallized as radial shape mainly coexisting with silicification; and Tur-3 with elongated shape is present in dacitic breccia with phyllic alteration.

Mineral Chemistry:

The geochemical composition of three types tourmalines points to the nature and the evolution of ore-forming fluids. Electron microprobe analyses of the studied tourmalines indicate that the Tur-1 and Tur-3 are dravite, and the Tur-2 is dravite to schorl in composition and they belong to alkaline group. The third type, unlike the other two, is characterized by poor zoning and higher values of Na, K, Fe, Mg and lower values of Ca. On Fetot-Ca-Mg ternary diagram, they plotted in the Ca-poor metapelites, metapsammites, and quartz-tourmaline rocks host. Magmatic genesis inferred from the higher Fe/(Fe+Mg) ratio for Tur-1 and Tur-2, while this ratio in the Tur-3 is different and shifted towards hydrothermal source.

Microthermometric Study:

Richards et al. (2006) present the fluid inclusion assemblages from quartz-tourmaline veins in sericitized wall rocks in the Dashkasan deposit consisting of hypersaline and rare vapor-rich inclusion. They have homogenization temperatures of 246° to 360 ℃, yielding salinities of 34.4 to 46.1 wt% NaCl equiv. (Richards et al., 2006). Fluids inclusions studies on quartz-tourmaline-pyrite veins related to transition between stage-1 and stage-2 of mineralization in the Dashkasan shows a salinity values from 15.9 to 16.8 wt% NaCl equiv. and homogenization temperature values between 185° to 254 °C.

On the basis of optical and scanning electron microscopy, three tourmaline types(Turs -1,-2 and -3) in the Dashkasan deposit, can be distinguished. Despite the lack of zoning in Tur-1 and Tur-2, the third type displays the poor zoning. The first-and the third-types of tourmalines are dravite (Mg-rich), whereas the second-type is dravite to schorl in composition. Magmatic genesis is reflected by higher Ʃ(Fe+Mg) and FeO/(MgO+FeO) ratios for the first two types. While these ratios in the Tur-3 is different and shifted toward hydrothermal source. To sum up, the occurrence of quartz-tourmaline-pyrite veins in the Dashkasan deposit is due to the existence of a fault system under the physicochemical performance of the ore-mineralized fluid by a sudden depressurization and probably gradual mixing with shallow water.

Garnet amphibolite and garnet micaschists of the Faryab complex, located in the southeast of the Sanandaj-Sirjan zone, are exposed immediately under the peridotites and sometimes a few meters away from the peridotites of this region with fault boundaries. Some garnet amphibolites mainly include poikiloblasts of garnet and amphibole, plagioclase, quartz, secondary minerals of epidote, biotite, chlorite, as well as oxide minerals of, magnetite, ilmenite, titanite and apatite mineral. Garnet micaschists include the main minerals garnet, amphibole, muscovite, epidote, plagioclase, quartz, and secondary minerals biotite, chlorite, rutile, apatite, titanite, and ilmenite. Considering the chemistry of garnet poikiloblasts and the chemistry of amphiboles, temperatures of 505 to 708°C and average pressures of 6.7 to 8.6 kbar (upper amphibolite facies) for garnet amphibolites and temperatures 450 to 650°C and average pressures of 6.7 to 7.2 kbar (lower amphibolite facies) have been determined for garnet micaschists. Accordingly, garnet amphibolites show the highest metamorphic degree, while garnet micaschists show a lower metamorphic degree. Such a situation indicates a type of geothermal gradient. Geochemically, garnet amphibolites can be classified in two groups. Group I, which together with garnet micaschists have the geochemical characteristics of sedimentary rocks, while garnet amphibolites of group II show the typical characteristics of basalts. The Faryab metamorphic complex next to the ophiolitic remnants of the region may indicate the evolution of this ophiolitic complex in a Neotethys accretion-subduction position during the Upper Cretaceous.

The Garmkhani-Meyham region is located in SE-Qorveh city, in the northwestern part of the Sanandaj-Sirjan zone. This area includes a variety of regional and contact metamorphic rocks. Microprobe data of mineral chemistry show that amphiboles, magnesium-hornblende type; plagioclases, andesine to albite type; biotite crystals, siderophyllite type; white mica, muscovite type and epidotes, clino-zoisite type are in composition.  Based on the mineral chemistry of amphibole, the magmatic series of its constituent magma is the subalkaline and its tectonic environment is supra-subduction. Geothermometric estimates on the amphibole and plagioclase minerals in amphibole- schists, a temperature ranges from 464 to 570 °C and pressure between 3 to 5.6 kbar illustrate passing from greenschist facies to amphibolite facies.

The Gol-e- Gohar iron ore mine, in southwest of Sirjan city, is structurally located in the Sanandaj-Sirjan zone and is mostly composed of Paleozoic metamorphic rocks. The highest degree of metamorphism of the rocks of the region is related to the amphibolite facies. The studied of amphibolite indicates that the hornblende and plagioclase are the main and biotite, sphene, quartz, tourmaline and opaque minerals are the accessory minerals. Secondary minerals include chlorite, epidote, calcite, iron oxides, and sericite that have been developed during the alteration phases, as well as chloritization and epidotization of biotites and amphiboles as evidence of retrograde metamorphism. Based on amphibole mineral chemistry studies, amphiboles are formed as a combinations of magnesio hornblende, paragasite and winchite types. According to Geothermobarometry studies, amphiboles are formed under conditions of high oxygen fugacity and at a temperature of 600 to 750° and an approximate pressure of 3 to 7 kbar.

The study rocks outcropped in the northeast Semnan area. These rocks, composed of monzogabbro-monzodiorite, was intruded in the Eocene sedimentary and volcanic rocks. Plagioclase and clinopyroxene are the main constituent minerals of these rocks. The study rocks represent granular and poiiklitic textures. Based on EMPA data, clinopyroxenes, and plagioclases are diopside and augite and andesine, labradorite and bitonite in compositions and formed in temperatures ranged from 1104 to 1168 and less than 700 °C respectively. On the basis of tectonic discrimination diagrams, the investigated samples fall into volcanic arc domain resulted in subduction of Neothetian oceanic lithosphere beneath Central Iran block.

The Sabalan is one of the Pliocene-Quaternary volcanoes in northwestern Iran. Based on the activity history, the Sabalan volcanic rocks can be classified into two rock groups: Paleo- and Neo- Sabalan volcanic rocks. Paleo-Sabalan was constructed during the Pliocene-Pleistocene inmultiple eruptions between 4.5 and 1.3Ma, whereas Neo-Sabalan activity initiated after a series of violent explosive eruptions during the middle to late Pleistocene (545 to 149 ka; Ghalamghash et al, 2016). The Paleo-Sabalan volcanic rocks are trachy-andesitic to andesitic and rarely trachy-dacitic and Neo-Sabalan volcanic rocks are generally dacitic to andesitic.

Field investigation and sampling, petrography and mineral geochemistry are different part of our studies during this project. Mineral chemistry have been performed on two thin-polished sections of Paleo-Sabalan olivine basalt and Neo-Sabalan trachyandesite in Iran Mineral Processing Research Center. In this center, a Micro-probe model EPMA Sx100 model made by Cameca company with a voltage of 15 kV (Kv: 15 Kev), current intensity of 20 nm (nA), a diameter of 5 um and a detection limit of 500 ppm for microscopy and point chemical analysis Used. Sample preparation for microprobe studies has also been done in Iran Mineral Processing Research Center using carbon coating device.

Plagioclase composition in the Paleo-Sabalan volcanic rocks in the oligoclase to andesine range, and in the Neo-Sabalan volcanic rocks in the range of oligoclase, to andesine. K-feldspars are sanidine and orthoclase. The Olivine and pyroxenes of the Paleo-Sabalan volcanic rocks have chrysotile and diopside-augite compositions, respectively. The most of the mica in Neo-Sabalan lava are Biotite. The most amphibole of Neo-Sabalan lavas are Magnesiohornblende, and rarely are edenite. Based on the mineral chemistry diagrams of Sabalan volacic rocks have a sub-alkaline and calc-alkaline nature that have formed in the orogenic environment. Paleo-Sabalan clinopyroxenes have crystallized at 5 to 10 kbar pressure (equal 17.5 to 35 Km depth). The amphibole phenocrysts have crystallized at a pressure of 1 to 3 kbar (equal 3.5 to 10.5 Km depth) and a temperature of about 725 to 750 °C.

Considering the crystallization temperature of amphibole (725 to 750° C) and biotite modeling with FMQ buffer oxygen fugacity at the time of biotite crystallization was estimated to be -16 to -16.50. Probably, high oxygen fugacity and the presence of aqueous minerals indicate the effect of water-rich old subduction environment on the source of primary magma of Sabalan volcano.

Dalfard granitoid complex is located in the southeast of Kerman Province between  57˚ 30 ˊ to 57° 45 longitudes and 28˚ 55ˊ to 29˚ 10 ˊ latitudes. This granitoide complex contains granite, granodiorite, quartz-diorite, diorite, in the margins, and is mainly composed of quartz-diorite. The main texture is granular and include quartz, plagioclase, amphibole, biotite and alkali-feldspar, with some mafic microgranular enclaves in them. The EMPA data showed that plagioclase are andesine and alkali-feldspar with orthoclase composition. Biotites with Fe/Fe+Mg > 3.3 rato fall in the magnesium-rich biotites area. Amphiboles are calcium type and they have magnesiohornblende in composition, which indicates that their host magmas are I-type. The low values of Na2O in amphiboles, their calc-alkaline nature, and the high oxygen fugacity indicate that they belong to the subduction environment and mantle derived magmas along with the crustal compounds contributed to the formation of their host magmas. Geo-thermo-barometry calculations estimate the average crystallization pressure of 1.4 kb and temperature of 681 °C for the studied hornblende.

Amphibolites are a major component of the northern Makran ophiolite belts. They include both foliated and massive types. They are diverse in mineralogy and include amphibolite, garnet-pyroxene amphibolite, and epidote-garnet amphibolite. In addition to plagioclase and amphibole, which are the main constituent phases, other minerals such as zircon, sphene and quartz are also found in amphibolites. According to mineral chemistry, the amphiboles in these rocks are calcic type, and compositionally range from magnesian to ferrohornblende. Geothermobarometry of the amphiboles indicates a pressure ≤ 7 kbar (4-6 kbar) and a temperature range of 750-800°C. Thus, geothermobarometry of amphiboles shows that the Makran amphibolites were metamorphosed at high-temperature and low to medium pressure metamorphic facies (Abukuma-type metamorphism).

The Chore-Nab iron deposit is located in the northwest of the Zanjan-Zaker district. The deposit was formed in quartz monzonite, syenogranite, and granodiorite bodies introded into Lower Cambrian volcanic (andesite) and sedimentary units (siltstone, tuff, and ignimbrite) in the Tarom-Hashtjin metallogenic province. Iron mineralization occurs as brecciated, massive, disseminated, and vein-veinlet types. Major alteration minerals include actinolite, albite, magnetite, epidote, phlogopite, k-feldspar, and biotite. The main sulfide minerals are pyrite, chalcopyrite, and bornite. Based on field and mineralogical studies, sodic-calcic, potassic, propylitic, sericitic, siliceous, and argillic alterations have been identified in the deposit. Sodic-calcic alteration (albite-actinolite-magnetite), characterized by massive and brecciated magnetite in the depth, calcic (actinolite) and potassic (secondary biotite) alteration in the middle levels associated with vein-veinlet sulfide mineralization and finally propylitic alteration (chlorite-epidote) in the shallow levels are observed. Based on the results of chemical analyses, the clinopyroxenes in the alteration zones (mainly sodic-calcic) are mostly augite and less commonly diopside. Plagioclase has a range of albite compositions. Amphiboles are calcic and often tremolite and magnesio-hornblende. Finally, the absence of Cl in the composition of the amphiboles of the Chore-Nab deposit and the presence of at least two Cl-rich amphiboles in all the IOCG deposits of the Carajas mineral province can be attributed to the lack of influence of replacement mechanisms generated by Cl-rich hydrothermal fluids during sodic-calcic alteration.

The Iron-apatite deposits of Choghart and Chadormalu mining district are located in the western margin of the Bafq block and are hosted by Precambrian metamorphic basement complex, Late Precambrian sedimentary-volcanic units, and Late Precambrian-Early Cambrian plutonic rocks. The origin and relation of the rocks for a long time, which are known as metasomatites, have always been questioned. Based on petrography and mineral chemistry studies, five types of hydrothermal alterations have identified in these rocks. The oldest one is Na-alteration, which occurs at farther distances of iron deposits and is characterized by the presence of chessboard albite. The youngerst one is sodic-calcic alteration which is widespread and two-stages of the metasomatism model are characterized by the presence of tremolite-actinolite and is synchronous with the Fe-oxides. Potassic alteration occurs after two previous alteration phases, because of the influence of K-rich fluids and the formation of K-feldspar and secondary biotite. Silicate and sericite alteration has occurred as a late phase in the region.

The studied area is located in Ardabil province and the northeast of Meshkinshahr city and structurally in Alborz-West-Azerbaijan zone. Tephritic dykes have pyroxenite and gabbro xenolites. Mineralogy of tephritic dykes and xenolites includes plagioclase, clinopyroxene, analcime, amphibole, olivine and phlogopite. Porphyric, microcrystalline, granular and cumular microlytic textures are their main textures. According to the mineral chemistry data as well as the presence of shaped, homogeneous and coarse analcime crystals, it can be concluded that the analcime crystals are secondary and as a result of delayed magmatic reactions under hydrothermal conditions have been formed on the primary leucite crystals. The composition of olivine in gabbro xenoliths is chrysolite. The chemical composition of pyroxene mineral in tephritic dykes and gabbro xenolites is diopside. The studied clinopyroxenes with alkaline composition show good adaptation to the tectonic environment of the magmatic arc. Clinopyroxenes are also formed at low to medium pressures, indicating their crystallization during magma ascent and at different depths. The amount of ferric iron in clinopyroxenes indicates high oxygen fugacity of magma. Clinopyroxenes of Tephritic and Gabbroic dykes are formed at 10 and 12 kbar pressure, temperature between 950 and 1100 ° C and depth between 35-35 and 40-50 km. The chemical composition of amphiboles related to pyroxenite xenolite is  calcic and magnesiohastingsitic amphiboles type . The average geometry of the barometer based on the amount of aluminum for pyroxenite xenoliths is 7-9 kbar. Thermometric studies indicated that the amphiboles were formed at 900-950 ° C. The chemical composition of mica is phlogopite, and the number of magnesium in mica is 0.77.

Sabalan is a young member of the Sanuzui volcanic assemblages, belonging to the Alborz Magmatic Arc (AMA(. In Sabalan mountain range, a series of volcanic rocks with a combination of andesite, basaltic andesite, rhyodacite and trachyandesite are present. The  texture of these rocks is often porphyritic with microlithic paste, porous porphyritic and sometimes glomeroporphyria, sieve and trachyte. Major minerals include clinopyroxene, plagioclase, and one or more mafic minerals such as hornblende and pyroxene. Secondary minerals include opaque minerals, iddensite, biotite, chlorite and calcite. Investigation of mineral chemistry of basaltic rocks in the region shows that the composition of calcium plagioclase crystals is moderate (An72-93(. Based on temperature–barometric diagrams of plagioclase and amphibole, a temperature of 540 to 750 oC and pressure of 5.30 to 7k have been calculated, which corresponds to the depth of the middle to lower crust. Mineralogical studies and whole rock geochemical analysis show that these rocks formed in a tensile and intercontinental zone.

Alam- kuh granitoid intrusion is located in the western part of kelardasht, Central magmatic Alborz structural zone. Alam- kuh granitoid intrusion consist of alkaligranite, syenite, and syenodiorite to monzonite rocks. In the northern part of Alam -kuh intrusion, there are mafic enclaves that represent the magma mixing and mingling process. it consists of plagioclase, quartz, alkali feldspar and biotite minerals. Types of pertite and myrmekite textures associated with granular, microgranular and microgranular porphyry textures observed in these rocks. According to mineral chemistry and whole rock chemistry studies, intrusion rocks are I-type which are typically of shoshonites and are aluminous, metaluminous. Alam- kuh samples are shown enriched in light rare earth elements (LREEs), and La, Rb, Th, Tb elements and depleted in Ba and Zr elements. Based on the major element oxides, tectonically, located in the volcanic arc granitoids (VAG) .Primary magma of district igneous rocks were produced by the melting of the underlying crustal protolith (amphibolite) and (meta-graywacke ), and the basaltic magma derived from the mantle which replaced in the lower crust could be thermal origin for partial melting of crustal source and mixed with crustal felsic magma. According to studis, In the stretching environment of Alborz Magma Bow, Lithosphere mantle and stenospheric mantle, Both were involved in the birth of a mantle with different stocks. Mixing two magmas with mantle and crustal origins and subtraction and crystallization, The most important processes were the development of magma and the diversity of rocks in the region.

Saray volcano is an extinct volcano and is located in the east of Urmia Lake. This volcano mainly consists of Leucititic lava flows and their related pyroclastic materials forming a Sequence which repeated more than five times. Leucite phonolitic dykes, Lamprophyric (Minette, Monchiquite and Spessartite) lavas and dykes, Trachytic domes and dykes, Syenitic dykes and a small syenitic stock are other rock types of Saray volcano. Since clinopyroxene is present in all rock types of this volcano, mineral chemistry study of clinopyroxenes in all rock types of Saray volcano, could help us to explain the relationship between different rock types. Clinopyroxenes of Saray volcano have diopside, salite and fassaite compositions. The majority of studied clinopyroxenes crystallize under 3-4 kb pressure and 1150 centigrade temperature. Tectono-magmatically speaking, these clinopyroxenes were mostly formed within plate basalts. Although the composition of rock types of Saray volcano is very different, almost constant composition of clinopyroxene in all rock types, show the same origin for all clinopyroxenes. However, it can be concluded that all rock types have the same origin.