جستجوی مقالات مرتبط با کلیدواژه "دما- فشارسنجی" در نشریات گروه "زمین شناسی"

The Dalayon granitoid mass is located in the south of Borujerd, in the north of Lorestan province and, is part of the Sanandaj-Sirjan zone. The lithological composition of this mass includes granodiorite, granite, pegmatite-granite, tonalite, quartz diorite, tourmaline-bearing pegmatite, and quartz-tourmaline veins intruded into volcanic and metamorphic rocks. The minerals set of granodiorite mass with color leucocratic to mesocratic index mainly minerals quartz, plagioclase, orthose and microcline and secondary minerals biotite, muscovite, zircon, garnet, apatite, rutile, leucoxene, titanium minerals and sphene. The indicator mineral of ferromagnesian in these rocks is biotite, which has a primary nature rich in magnesium and poor in chlorine in composition. The value of Fe/Fe+Mg ratio shows an average 0.44(apfu), that indicates that the studied micas are placed in the range of biotite and between siderophiles and anite poles. The average crystallization temperature of biotites is 681ºC and the average formation pressure is 2.95kb based on the total aluminum of biotites, which indicates formation at a shallow depth. Based on the proportions of MgO, FeO and Al2O3 in biotites, the magma that produced this mineral is of the calc-alkaline type. The existence of relatively high fugacity of oxygen and oxidant environment indicates magma of mantle-crust origin and host rock of magnetite granitoid series and I-type granitic rock for biotites.

The Hossein Abad area is located 120 km southeast of Zanjan. The volcanic rocks in this area belong to Eocene and younger a ges. Volcanic rocks include dacitic, trachyandesite and andesitic lavas, as well as tuff. Volcanic rocks have quartz, alkali feldspar, abundant plagioclase, pyroxene and amphibole. The alkali feldspar is Sanidine and plagioclases are oligoclase and andesine. The Porphyritic, microlithic porphyritic, glomeroporphyritic and poikilitic textures are predominant in these rocks. Examining the mineral chemistry of rocks in the study area shows that the clinopyroxenes are diopside and augite. Amphiboles in these rocks are magmatic and calcic with the chemical composition of pargasite. Based on magmatic diagrams, rocks in studied area are alkaline. According to the thermobarometric diagrams, these rocks have formed at temperature and pressure ranges of 700-750℃ and 5-6.5 kbar respectively. These values correspond to the depth of middle-lower crust. The rocks are formed in the active continental margin.

The studied area (Saqqez) is located in the north of Sanandaj-Sirjan zone in the Kurdistan province, northwestern Iran. Andesite and basaltic-andesite rocks contain amphibole, plagioclase, clinopyroxene, and orthopyroxene minerals with porphyritic and seriate textures. The composition of amphiboles ranges from magnesio-hastingsite, magnesio-hornblende to tschermakite-pargasite. Pyroxenes are augite Wo45.39 - 39.33 En40.37-40.26 Fs20.49-13.89 and enstatite Wo 2.842-3.287 En59.863-71.04Fs26.083-36.850 in compositions. The anorthite content in plagioclase is between 67 and 80 (wt.%) and their composition varies from labradorite to bytownite crystals. Thermobarometry through the method of Al- amphibole indicates crystallization temperature is between 895 and 961 °C with 2.11 - 4.59 kbar pressure. Moreover, the amount of Ti, indicates temperature crystalizing in the range 800 to 950 °C for amphibole. Clinopyroxene mineral chemistry based on the type of pyroxene shows that the studied volcanic rocks were crystallized at temperatures and pressures of 1100-1250 °C and 2-10 Kbar, respectively. Also, the amount of AlIV and Si indicates that amphiboles were crystalized at low pressures, which is consistent with the amount of AlIV/AlVI in the low to medium pressure pyroxenes of the investigation. Furthermore, the amount of AlVI+2Ti+Cr and Na+AlIV in the pyroxene crystals and LogƒO2 and Fe# values in studied amphiboles show they were crystallized in high oxygen fugacity.

The studied area is located in the southeast of Shahrood, north Torud, and northeast of the Central Iran structural zone. The area is one of the Iranian basement terrains which include a wide variety of igneous and metamorphic rocks. The study gabbroic bodies form a small part of this complex and their essential minerals are Plagioclase (labradorite, bytownite), pyroxene (calcic group and augite and clinoenstatite composition), olivine, biotite, and amphibole (calcic group and pargasite and pargasite hornblende composition). Based on the chemical composition of minerals, the magma forming of these rocks has calc-alkaline nature and during their crystallization, the fugacity of oxygen has been high. Geothermometry of pyroxene and amphibole suggest crystallization equilibrium temperatures at gabbroic rocks, for pyro,xene are  900-1200°C and for amphiboles are 820-990°C‑ respectively. Geobarometry calculation of these rocks, using an amount of total amphibole aluminum (Alt is between 2-2.5), estimated between 6.52 to 8.9 kbar and for pyroxene between 5 to 7 Kbar. These conditions are equivalent to the formation and final equilibrium at depth of 23 to 27 km of the lower crust.

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.

The regional and  contact metamorphic rocks of the studied area are located in the west of Hamedan city and Alvand plutonic body as a part of the northern part of the Sanandaj-Sirjan belt. This metamorphic complex consists of slate, garnet mica schist, amphibole schist and tremolitite in regional metamorphic rocks and spotted schists, mica hornfels, epidote amphibole hornfels and cordierite hornfels in contact metamorphic rocks. The analyzed minerals in these rocks include biotite, garnet, staurolite, amphibole and cordierite. EMP chemical analyses indicate that the composition of garnet is almandine, the composition of biotite is siderophyllite and amphibole is actinolite. Staurolite has iron-rich composition and cordierite has intermediate composition (iron-magnesian). Thermometric calculations based on biotite in garnet staurolite schists show a temperature of about 555°C, and the temperature of about 511°C was determined by the garnet-biotite pair method. Due to the presence of staurolite and the absence of kyanite and other medium and high pressure minerals, the pressure of 3 to 4 kilobars is possible. The type of metamorphism of the study area is suggested to be related to a  subduction tectonic environment. The stability of the garnet + staurolite assemblage requires the presence of water in the environment.

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.

In the Shourestan area, 14 kilometers west of Sarbisheh city, in South Khorasan province, volcanic rocks with pyroxene-andesite composition belonging to Eocene-Oligocene are exposed. The constituent minerals of these rocks include plagioclase and pyroxene. The composition of plagioclases have range from Ab32, An68 to Ab58, An42 and are andesine-labradorite type. Clinopyroxene and orthopyroxene have diopside-like augite and enstatite composition, respectively. The crystallization temperature for clinopyroxene and orthopyroxene were about 1175 and 1200 °C respectively and the pressure (for both types) was 2 to 5 kb. The geochemical data of whole rocks show that the andesitic lavas of Shourestan have high potassium calc-alkaline nature and the amount of Mg# in them varies from 40.97 to 60.97, which indicates the role of mantle components in their formation. These rocks show signs of differentiation including LREE/HREE ((La/Yb)N) between 9.95 to 12.42, LREE/MREE ((La/Sm)N) between 3.53 to 6.55, MREE/HREE ((Sm/Yb)N) between 1.89 to 2.99. High ratios of Zr/Nb (9.81-22.10), Th/Nb (0.68-1.79), Th/Ta (7.29-24), and Nb/Ta (9.69-15.66) along with the pattern of LIL elements, support the possibility of different degrees of crustal contamination-assimilation of magma during its ascent to the earth's surface. The studied rocks have low ratios of Ce/Y (2.44-3.48), (Tb/Yb)N (1.17-1.39), Sm/Yb (1.92-2.78), and relatively flat MREE-HREE pattern that confirms the melting of the subcontinental lithospheric mantle in the field of spinel stability and at a depth of fewer than 75 kilometers.

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.

Based on field observation and petrographic evidence, by progress in metamorphic degrees, a wide variety of metabasites have formed following the metamorphism at amphibolite facies (metamorphism M1) in the east of Jandaq. Thermobarometry of plagioclase- amphibole pairs indicate temperature ranges were 642-692ºC  and 688-712 ºC for epidote amphibolites and garnet amphibolite, respectively, in a pressure range of 8 and 11 Kbar, correlating with transition from middle amphibolite to upper amphibolite facies. In addition to this metamorphic phase, petrographic signatures indicate further metamorphic phases concerning this region's geological phenomena. Based on brittle deformation in amphiboles, and epidote and quartz formation in their fractures, these rocks have undergone some degrees of retrograde metamorphism (<700 ºC; metamorphism M2) at greenschist to lower amphibolite facies. Rock foliation and mineral orientation, aggregate shape preferred orientation (ASPO) of titanite crystals along foliation, and syn-tectonic euhedral garnets indicate prograde metamorphism toward amphibolite-upper amphibolite facies (metamorphism M3). Finally, under greenschist facies condition, minerals such as chlorite and actinolite were formed in these rocks (metamorphism M4). The formation of chlorite and actinolite in the rims of the primary crystals shows that these rocks were finally affected by metamorphism at greenschist facies (M4 metamorphism).

There are discontinuous outcrops of volcanic rocks in the West Azarbaijan province and in the north of Maku city. These volcanic complex were bimodal and compose of acidic and basic lava and pyroclastic rocks. Mineral chemistry studies show that clinopyroxenes in the studied rocks are diopside. These pyroxenes have a high magnesium number (0.87 to 0.99). Magma series and tectonic determination diagrams show that the basaltic rocks that make up the studied clinopyroxenes have an alkaline nature and were formed in a whitin plate environment. According to geothermobarometry studies, clinopyroxenes were formed at temperature 1100 - 1250 ° C and pressure of 3 - 9 Kbar. The depth for generation of magma was at about 22 kilometers.

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.

The Oshvand Skarn deposit is located about 10 km east of Nahavand city in the Sanandaj-Sirjan structural zone. In this area, garnet (grossular-andradite) is the most abundant mineral in the skarn zone and their compositions are in the range of Adr(67.2 - 45.9%) Gro(50.1 - 31.8%) Sps(1.8 - 0.3%) and Prp(2.5 - 0.6%). EPMA data indicate a decrease in andradite and increase in the amounts of grossular and pyralspite group from the core to the margin of the garnet minerals. Increasing the substitution of Al by Fe+ 3 from the core to the rim of the garnet crystals indicates an increaseing FO2 during the growth of the garnet crystals. Pyroxene is the second most abundant mineral in the skarn zone and has a more homogeneous composition than garnet. The main pyroxenes of this deposit are in the range of hedenbergite to diopside with the combination of Fs(41.2 - 30.6%) En(26.6 - 9.5%) and Wo(49.3 - 42.8%) which has an average ratio of Fe/(Fe + Mg) in the range of 0.81 to 0.53. Thermobarometry studies indicate the formation of the progressive stage of skarnification at a pressure of 1 to 2 kbar and a temperature less than 600°C, depth of formation is about 5 km and  FO2 is about -16 to -27. The EPMA results of garnets and pyroxenes of skarn zones indicate that their composition is located at the range of Fe-Cu-Au type skarns.

The geochemical characteristics of materials in the environment are related to the chemical properties of the sources. In other words, the concentration of heavy metals in the soil depends on the type and chemistry of the parent rocks, which has formed the soil through the weathering processes and has led to different concentration of heavy metals in the soils. In addition to the composition of the parent rocks, a variety of natural and man-made factors are effective in increasing element concentration in the environment which causes intense pollution. Therefore, in short, the earth has a direct impact on human health through the food chain (eating and drinking) and the inhalation of dust and gases. Thus, the main purpose of this study is investigation and monitoring the arsenic, antimony, lead and cadmium concentrations and plotting the map of pollution distribution in the agricultural soil of Bardsir catchment.

Position of sampling points is determined according to expert judgment based on previous research, topographic maps, geology, satellite images and field study. These were selected to obtain the suitable distribution and zoning map of the study area. Also, characteristics identify the effect of geology on the pollution of the study area. 105 samples of composed agricultural soils were collected by averaging method from less than 10 cm in depth to prevent the potential effect of anthropogenic pollutants. Samples were sieved with a 2 mm sieve and particles smaller than 200 mesh were sent to the laboratory for 4-element chemical analysis by ICP-MS method. Statistical analysis was performed to measure the concentration of heavy metals, index of geo-accumulation, degree of pollution, risk potential factor and ecological risk.

The results show that agricultural soils are polluted by arsenic and antimony (14% in terms of arsenic and 29.5% in terms of antimony), more than allowable levels in some parts of the study area. Statistical analysis also verified that only As and Sb show low to intense pollution while the contamination and risk of Cd and Pb are low. The As zoning map shows that the contaminated agricultural soils are located in the center and north (basin outlet) of the study area. This may be related to the irrigation with polluted river, which is located in the downstream of volcanic outcrops, or to the synergy of different polluted waters at the outlet of the area or flood irrigation. These can transfer the dissolved pollutants from upstream to agricultural land. The Sb concentration zoning shows that the agricultural soils with the highest pollution are located in the upstream and near outcrops including south, west, east, and center of the study area, which is due to the low solubility of antimony compared to arsenic.

The overall results indicate that the agricultural soil is polluted to arsenic and antimony in some areas. Evaluation of the origin of these elements showed that the pollution has mostly geogenic resources and is derived from alteration and Cenozoic volcanic outcrops while anthropogenic pollution showed a small contribution to pollution. The transport and re-precipitation of heavy metals is controlled by dissolution- precipitation and adsorption-desorption reactions, and its transporting is controlled by oxyhydroxides of these elements in the study area.

Damavand volcano is a large composite cone (≥ 400 km3) with height elevation (5678m) above sea level, in Central Alborz. This volcano consists of two buildings including old lavas between 1.8 to 0.8 Ma in the northern and eastern part of the current cone and young lavas with about 0.4 to 7 ka years in the south and west part. Trachytic and trachy-andesitic lavas are the most abundant lavas of this Quaternary volcano. The current Damavand cone, which is about 600,000 years old, is located above the old and eroded building which include periodically of andesitic-trachyte lava flows and pyroclastic flows with small eruptions of mafic lavas. Geological studies of this volcanic cone have been mostly based on geochemistry and petrogenesis, and a little data on mineral chemistry and termo-barometry are available. Geologically, the Damavand volcano bed rock has been formed since the Precambrian deposits, mainly on Mesozoic deposits (Shemshak and Lar Formations), and formed in the youngest geological period (Quaternary), about 10,000 years ago to the present. Late Cretaceous volcanic activity in Alborz is covered by shallow and progressive Eocene sediments in most places, but the Middle Eocene activity with Tofit composition is significant. The intensity of Alborz volcanic activity continues during Tertiary, but is not uniform, as its maximum is in the late Eocene and Oligocene, and after a period of relative inactivity, activity re-intensifies in the Pliocene.

After initial microscopic studies, suitable samples of thin section were prepared and sent to Iran Mineral Processing Research Center for analysis. The analysis performed in this center is performed by the electronic microprocessor model CAMECA-SX 100 made by the French company Cameca. This device is equipped with a spectrometer with an electron diode receiver and works automatically based on a high accuracy of 1% and the simultaneous operation of several diode detectors and electron beam stability with a carbon coating.

Volcanic activities in the middle part of the Central Alborz Mountain were started about 1.8 million years ago with the eruption of lava and pyroclastic rocks, which has caused the formation of the current Damavand cone, in the northern part of of Tehran. Damavand trachyandesites in Lar region have hyaloporphiric and microlitic porphiric texture with main phenocrysts include feldspar (oligoclase to labradorite), clinopyroxene and amphibole, and mica, apatite and opaque titanomagnetite to ilminite minerals. Mineral chemistry studies of clinopyroxenes show that these minerals with a percentage (Wo14-47, En0.1-47, Fs7-85) show the composition of diopside, which are in the range of calcium pyroxenes, magnesium-iron and alminodiopside. High Magnesium Number (80-79 = Mg #) of studied clinopyroxenes, shows that trachyandesites of Lar region generated from the low evolution and low-silica parent magma. The zonation of clinopyroxenes with Fe3 + fluctuations indicates the oxidant environment of the magmatic reservoir of these rocks, which is also confirmed by the high amounts of Fe3 + mica. Changes in the amounts of calcium and silica from the core to the rim of these minerals indicate crustal contamination of these rocks. The amphiboles composition is magnesium hostengite and mica show the composition of phlogopite. Phlogopites are characterized by Fe # <0.33, TiO2 6.03 - 7.7% and high Mg # number. Mineral chemistry studies indicate the sub-alkaline nature of the host magma. Thermo-barometric studies of clinopyroxenes show these minerals form at temperature range between 1112 to 1191 (± 50) ° C and pressure range of 6.2 to 6.9 kb, at depths of 20 to 22 km, with a water content of about 10%. Amphibole has a water content of about 4 to 7% and high oxygen fugacity range from -5.83 to -6.15. Thermal anomalies related to geothermal activity have been revealed based on remote sensing models that theoretically confirm the existence of hot zones containing melt at shallow depths. According to other researches, there is an unexposed igneous mass at a depth of about 22 to 35 km, which is somewhat consistent with the results of geophysical models based on a high-velocity P-wave mass at a depth of about 20 km below Damavand volcano (old cone area). Existence of non-equilibrium textures such as co-occurrence of aqueous and anhydrous minerals, reactive margins of phlogopites and amphiboles, non-equilibrium corrosion texture in feldspar, oscillatory and normal zoning and oscillation of iron oxides between the core to the rims of clino-pyroxene minerals indicate that Magmatic evolution of Lar lavas take place in an open system with different pressure, temperature, oxygen fugacity, and water content. Oxygen fugacity and water content of magma have increased during ascent to higher sections. Multiple magmatic chambers at different depths can be a justification for the local thickening of the crust under Damavand volcano.

The composition of phlogopites with Fe # <0.33, TiO2 6.3 to 7.7% and magnesium number (Mg #) is high and the formation temperature is 912 to 995. Mineral chemistry indicates the sub-alkaline nature of the host magma. Earth-temperature barometric studies of clinopyroxenes show that these minerals are formed in the temperature range of 1112 to 1191 (± 50) ° C and pressure of 6.2 to 6.9 kg, at depths of 20 to 22 km, with a water content of about 10%. Amphibole water content is about 4 to 7% and its fugacity is -5.83 to -6.15.

The study area is located in the N Turood, S Shahrood, and NE of Central Iran structural zone. Many basaltic dikes in this area intruded into the Eocene volcanic rocks and they also contain many gabbroic enclaves. Plagioclase (labradorite, bytownite-anorthite), amphibole (calcic, pargasite- magnesiohastingsite), and pyroxene (calcic, diopside-augite) are the essential minerals of these rocks. With the attention of the minerals chemistry, magma forming of these rocks has mainly subalkaline nature and during their crystallization fugacity of oxygen has been high. Geothermometry of these rocks suggest crystallization equilibrium temperatures are at 1100-1200°C for pyroxenes, and 825-888°C for amphiboles. Geobarometry calculation by using of Altot of amphiboles in host basaltic rocks, basaltic dikes and enclaves estimated between 8.51 to 9.21 kbar (depth of 30 to 33 km), 7.41 to 9.16 kbar (depth of 27 to 33 km) and 6.84 to 7.46 kbar (depth of 25 to 27 km), respectively. The chemical characteristics of studied minerals in differents diagrams show strong compositional similarities and indicate that nature and origin of these rocks are the same and most likely the magmatic reservoir or reservoirs of the studied basaltic rocks were at depths of 33 to 25 km of the lower crust.

The Gaz Boland area is located in Kerman Province, northwest of Shahr-e-Babak. This area is a part of the volcanic-plutonic belt of Urumieh-Dokhtar. Most of the exposed rocks in this region belong to Eocene age, however, the basalts with Pleio-Pleistocene age have also a relatively limited distribution in the region. The main texture of the basalts is microlithicporphyric and olivine, clinopyroxene and plagioclase form the main minerals. Due to the weathering and alteration processes, secondary minerals such as calcite, chlorite, and iron oxides have formed in these rocks. Based on the analysis of X-ray microprobe, the composition of pyroxenes is diopside-augite. The chemical composition of clinopyroxenes confirms the calc-alkaline nature for their parent magma of, which originates from the subduction-related tectonic setting. Based on clinopyroxene thermobarometric studies, the parent magma of the rocks, when crystallization of the clinopyroxene mineral with approximately 10% water under a pressure of 2 to 8 kbar occured, formed during uplift and before the eruption. The magma temperature variations during the crystallization of clinopyroxenes ranges between 1130 and 1249 °C.

In the Talu area at NE Damghan in the Eastern Alborz Zone, the Permo-Triassic carbonate sequences host several mafic igneous inrusions with olivine gabbro, gabbro and alkali-diorite compositions. The most important rock-forming minerals of these intrusions are olivine, clinopyroxene, amphiboles and plagioclase. These rocks have alkaline nature and their major and trace elements characteristics correspond to OIB-like mantle source. The olivines of these rocks are chrysolite, and the plagioclases are characterized by albite, oligoclase and labradorite. Clinopyroxenes are diopside, augite and salite in composition and characterized with alkaline nature (Non-orogenic). They crystallized in 6-11 Kbar, 1200-1250˚C and high oxygene fugasity conditions. Amphiboles are of calcic and high-Ti kaersutite type and crystallized in igneous conditions with mantle source. The amphiboles were crystallized in temperatures and pressures over than 950˚C and 650-750 MPa (equivalent to 6.5-7.5 Kbar).

In Zoolesk area, about 11km northeast of Sarbisheh city in South Khorasan Province, volcanic rocks including andesite, dacite and rhyolite have cropped out where andesitic lavas have the maximum distribution and have been studied in this research.The main textures of andesites are porphyry with microlitic-glassy groundmass, glomeroporphyry and vesicular. Minerals forming andesites include plagioclase, pyroxene, amphibole, biotite and rarely sanidine. Plagioclase phenocrysts have oscillatory zoning and sieve texture and so corrosion, rounding and resorption rims can be seen in the margin of some crystals. Based on microprobe analyses, the composition of plagioclases changes from Ab67,An33to Ab54, An46 and are andesine type. Clinopyroxene phenocrysts have augite with minor diopside composition (En39-41 Fs13-17 Wo43-47) and orthopyroxenes are enstatite (En41-74Fs13-43Wo2-3). The Mg# values in clinopyroxene and orthopyroxene are variable between 69-75 and 56-76 respectively. Thermometry studies showed that the crystallization temperature of clinopyroxenes is 1150 to 1200°C and for orthopyroxene is 1050 to 1100°C. The calculated pressure for genesis of clinopyroxene and orthopyroxene in the studied samples was less than 2 kbar.

Damavand volcano is situated in the central part of the Alborz mountain range along the southern margin of the Caspian Sea, North of Iran and also located about 50 km NE of Tehran. The basement of the volcano is made up of Paleozoic to Cenozoic sediments. Damavand stratovolcano consists mainly of trachyandesite-trachyte lava flows and pyroclastics formed in the past two Ma (Allenbach, 1966; Davidson et al., 2004). The erosion processes have formed valleys on the flanks of volcano like Talkhrud valley where a subvolcanic body of syenodiorite composition crops out that is considered as probably feeder dike of lateral vents. An investigation on the texture and mineral chemistry of this subvolcanic body has carried out to decipher crystallization processes and thermobarometry based on mineral-mineral equilibria, since it has been shown that minerals can record the entire range of pressure, temperature and composition of melts in which they develop during storage, ascent and emplacement. It is necessary to mention that petrography and geochemistry of the study subvolcanic body has recently been published by Aliakbari et al. (2020).

Minerals of two representative syenodiorite rock samples were analyzed on polished thin sections by electron microprobe at Oslo University in Norway, using a CAMECA SX100 instrument with analytical conditions of 15 kV accelerating voltage and 10 nA beam current. Excel and Minpet 2.02 software were used to calculate structural formulae of minerals and to plot their diagrams. A total of 66 point analyses of different minerals are used in this research.

The study subvolcanic intrusion, comprising syenodiorite, is cropped out in Talkh-rud valley located in the northeast of Damavand volcano flank. This sub-volcanic intrusion possesses porphyritic texture and consists of plagioclase, alkali feldspars, phlogopite, amphibole, clinopyroxene, apatite and titanomagnetite. Feldspars show signs of disequilibrium as coarse and fine sieve textures in their cores and rims. Mica and amphibole phenocrysts have breakdown reaction rims with opaque replacement. Amphibole crystals are highly opacitized and show replacement by brown mica. The intrusion is geochemically alkaline and shoshonitic and tectonically plots in the realm of within plate volcanics.Electron microprobe analyses show that the composition of plagioclase (An23.20- 41), is oligoclase-andesine, alkali feldspar (Or38.70-61), is sanidine, following the feldspar ternary diagram of Deer et al., (1992), brown micas K1.76 (Mg3.90 Fe1.21) [Ti0.67 Si5.58 Al2.24O20] (OH)4, on the classification diagram of Speer (1984), plot in the phlogopite field. Amphibole Ca1.79 (Mg3.21 Fe0.27 Al1.76) [Ti0.42 Al1.76 Si6.16 O22](OH)2, following the nomenclature of Leake et al., (1997) is magnesiohastingsite, and clinopyroxenes (Wo46.61-47.41 En42.38-44.79 Fs8.28-10.20), following Morimoto et al. (1988) are classified as diopside (Figures 5 to 9). Phlogopites show high TiO2 (5.9–6.3% wt) and a minor variation of MgO (16.3–19.6 wt %). In comparison with phlogopites that are in equilibrium with lower crust and mantle (Mg >5 apfu), the Talkhrud phlogopites have lower Mg (3.6–4.2 apfu). The experimental studies showed that the solubility of Ti in phlogopites increases with temperature and decreases with pressure for a given bulk TiO2 content (Tronnes et al., 1985). Magnesiohastingsite amphibole crystals are opacitized and show replacement by phlogopite. Composition of this secondary phlogopite is not different from primary ones (Table 3). The reaction rims of phlogopites and amphiboles indicate open system processes (Rutherford, 2008) and have been suggested as related to a slow ascent of magma (Rutherford and Hill, 1993).Numerous thermobarometers are employed to estimate the ranges of pressure and temperature of crystallization. Based on geothermobarometry calculations, clinopyroxene crystals formed from 1000 to 1184 0C and pressure ranges from 0.6 to 8.4 kb. Amphibole barometry shows crystallization temperature at 1000 0C and pressures ranging from 6.2 to 6.4 kb. Phlogopite also formed at 837 0C and pressures from 0.22 to 1.16 kb. Composition of phlogopite and amphibole indicate high oxygen fugacity during their crystallization. In addition, Mg number of amphiboles is higher than 0.7 indicating their mantle origin.

There are no tangible differences between chemical compositions of Talkhrud subvolcanic minerals with Damavand ones, for instance, titanium oxide values in the study amphiboles (magnesiohastingsite) are barely less than the reported amounts from volcanic amphiboles (kaersutite). In addition, subvolcanic pyroxene composition is diopside and alkali feldspar, sanidine. Furthermore, chemical compositions of amphiboles plot in within plate field of tectonic discrimination diagram of amphiboles. Hornblende-Plagioclase equilibrium temperature shows a range of 998.5 to 923.6 0C and plagioclase-alkali feldspar thermometry is in the range of 907.5 to 1018.3 0C. The presence of hydrous and anhydrous minerals, disequilibrium textures in plagioclase, reaction rim of phlogopite and amphibole may imply magmatic evolution in an open system, multistage crystallization and accumulation and storage in different levels of the crust.