The studied area is located in the S Shahrood, and NE of Central Iran structural zone. Many basaltic dikes in this area intruded into the Eocene volcanic rocks and some of them contain many gabbroic enclaves. Plagioclase (labradorite, bytownite-anorthite), calcic amphibole (pargasite-magnesiohastingsite), and calcic pyroxene (diopside-augite) are the essential minerals of these rocks. Magma forming of these rocks has mainly subalkaline nature and during their crystallization fugacity of oxygen has been high. Pyroxene and amphibole geothermometry suggest crystallization equilibrium temperatures of host basaltic rocks, dikes and enclaves, at 1100-1200° C and 825-1038° C, respectively. Al-in amphibole barometer in host basaltic rocks, dikes and enclaves show that pressures ranging between 8. 51-9. 21 kbar, 7. 41-9. 16 kbar and 6. 84-7. 46 kbar, respectively, and based on pyroxene at 2-8 kbar. . The geochemical characteristics of studied rocks show strong compositional similarities and indicate that the nature and origin of host basaltic rocks, dikes and enclaves are the same and most likely the magmatic reservoir of them were at depths of 33 to 25 km of the lower crust. Gabbroic enclaves were the result of the initial crystalline separation of host basaltic rocks, which was later brought to the surface by dikes from the depth of the magmatic chamber.

Spid pluton with Neogene age outcrop in the Urumieh-Dokhtar Magmatic belt. Amphibole in this intrusion is calcic and magmatic and its composition corresponds to magnesiohornblende to actinolite which reflects the type I granitoid. Geobarometry calculations show that the amphibole crystalized at pressure of 2. 5 to 3. 7 kbr corresponding to a depth of 8 to 12 km. Based on geothermometry of hornblende-plagioclase pairs and amphibole, a temperature of 752 to 865 ° C is estimated for crystallization of these two minerals at the Spid pluton. In addition, log ƒO2 for this pluton equals to-12. 18 to-15. 27, which reflects relatively high oxygen fugacity in magma and indicates the formation of this pluton in the subduction zone.

The Natanz plutonic complex is located in north of Isfahan and in the Orumieh – Dokhtar magmatic belt. Based on petrographic studies, the Natanz complex is composed of six rock types, which are granodiorite, quartz-diorite, diorite, gabbro, quartz- monzonite and granite monzogranit. The intrusive rocks of Natanz are related to the calc-alkaline magmatic series and I-type granitoids. These rocks are mainly composed of plagioclase, quartze, amphibole, alkali-feldspar, biotite, and pyroxene. The composition of olivine is Fo67-70. Pyroxene is Na-poor. The Composition of clinopyroxenes is in the diopside – augite range and orthopyroxenes are enstatite. All clinopyroxene analyses display compositional differences between cores and rims. Calcic amphibole with magnesiohornblende composition is one of the mafic minerals in the rocks. Composition of plagioclase is An11 (the minimum value in granite) to An92 (the maximum value in gabbro) and in some samples this mineral has normal zoning. Micas are Mg-rich biotite. Application of Al in hornblende barometry indicates a pressure of  » 2 kbar for the intrusion. Thermometry yields low temperatures, which probably reflects late stage, post - magmatic re-equilibration of the minerals.

Granitoid bodies of  south of Damghan with northeast-  southwest trend have intruded into the  Eocene volcanic,volcanoclastic and Cretaceous carbonate deposits. Recent studies have revealed that the Al content of hornblende in calc-alkaline granitoids varies linearly with pressure of crystallization, thereby providing a mean of determining depth of pluton emplacement. Based on results of electron microprobe analyses, amphibole minerals present in these bodies, according to Leake are ploted in the field of calcic amphiboles and show Actinolite, Actinolite-Hornblende and Magnesio hornblende composition. Calculated pressures of emplacement , using the Al-content of Hornblende, for these bodies ranging from about 0.51 to 0.98 Kbar (about depth of 1.8 to 3.5 Km).The altimate equilibration temperatures of minerals were calculated using different thermometers ranging from 613 to 772 oC.

In this study, some mantle lherzolites of Ashin ophiolite are investigated which contain evidence of a geotectonic/metamorphism during exhumation and obduction of oceanic lithosphere on the continental crust, after closure of Neo-Tethys Ocean. Based on petrography, their primary rock-forming minerals are orthopyroxene, clinopyroxene, olivine, and chromian spinel. Mineralogy and Geothermobarometry indicate that these 4-phase lherzolites were formed in the lithospheric mantle (at pressures ~ 21. 6 to 8. 6 kbar) by melt/wall rock reactions (at temperatures ~ 1012-1183 ° C). Then, they were emplaced and obducted on the continental crust along the fault zone of this region, and consequently deformed. The first ductile deformation event occurred in the depth of lithosphere and resulted in high-temperature mylonitization at temperatures higher than 600 to 800 ° C. Mineralogical features confirm pressure decreasing of this stage by subsolidus reaction of pyroxene and spinel and substitution of plagioclase and olivine. Therefore, petrography and thermobarometry data are indicative of the spinel to plagioclase lherzolite facies for these rocks. Finally, they partially underwent brittle and cataclastic deformation at temperatures below 600° C and lower pressures and depth during exhumation. However, most of plagioclases were replaced by with prehnite, pumpellyite, chlorite, hydrogrossular and xonotlite minerals by further alterations.

On the basis of geothermobarometric calculations, amphiboles in volcanic and subvolcanic rocks belong to Upper Jurassic volcanism of Sanandaj-sirjan zone in north of Shahrekord. Using Hamarstrom, Schmidt, Johnson - Rutherford and Hollister methods, amphiboles have crystallized about 635 to 715oc and 2.68 to 7.5 kbar at the depth about 17 to 25km. The result of calculations has moderate accuracy. The lower FET/ (Fet+Mg) ratio in amphiboles is characteristic of calc-alkaline magma suites. Calculated temperatures, pressures and depths for amphiboles is coincide with a subduction tectonical environment. The maximum depth of crystallization of amphiboles is 25km and subduction angle is lower than 45 km on the basis of 35 km distance between this volcanic belt and main Zagros fault. Aliv measures of amphiboles are higher than 1.5 that indicates an island arc suite. The presence of this old island arc had predicted in Zagros orogenic belt.

The fibrolite garnet staurolite mica schist and staurolite garnet mica schist cropped out around the northwest of Khalaj, south of Mashhad in a SE-NW direction along the metamorphic complex of Kuh-e-Majuni. They have similar mineralogy and consist of quartz, annite, staurolite, almandine, muscovite, zircon, and ilmenite; however, fibrolite in fibrolite garnet staurolite mica schist, and chlorite and tourmaline in the staurolite garnet mica schist are additionally found. Application of garnet - biotite thermometry and GBMAQ barometry indicates the temperatures and pressures of 560 and 605oC / 3.5 and 5 kilobar for fibrolite garnet staurolite mica schist and temperatures of 489 and 547oC (in 3.5 to 5 kilobar) for the staurolite garnet mica schist. Pressure and temperature increasing during the garnet growth indicates the effect of regional and contact thermal metamorphism on these rocks. Based on mineral paragenesis in KFMASH system, the metamorphic degree of regional metamorphism was about lower amphibolite (in staurolite garnet mica schist) to middle amphibolite facies (in fibrolite garnet staurolite mica schist). Meanwhile, intrusion of the Khalaj granitoid and its thermal diffusion raised the metamorphic temperature up to lower amphibolite facies (in staurolite garnet mica schist) and middle amphibolite facies (in fibrolite garnet staurolite mica schist), and consequently, this caused the fibrolite formation in the sample close to the pluton (i.e. fibrolite garnet staurolite mica schist).

APG2 is a computer application designed for amphibole-plagioclase Geothermobarometry. It is the first updated version of APG and supports 4 thermometer models and 6 barometer models involving either amphibole-plagioclase or amphibole only. APG2 has capability to integrate all 4 thermometer models with 6 barometer models and produce 24 different states which user can export them all at once to an Excel table. APG2 works in both graphical and analytical way. APG2 is also able to calculate the H2O content and Oxygen fugacity (logfO2) of magma hosting amphiboles.

Damavand stratovolcano is in Alborz Magmatic Belt (AMB), in the north of Iran, and the Iranian plateau. This large dormant volcano was constructed with a composite large cone (more than 400 km2). Damavand is known as the highest mountain (elevation ~5671 m) in the Middle East and South Asia. The youngest known eruptions of Damavand volcano (7.3 Ka), which mostly erupted on the western side of the summit, are composed of trachyandesite, and trachyte lavas with pyroclastic while the older eruptions (1.8-0.6 Ma) consisting of alkali olivine basalts, tephrite basanite, and trachyandesite, emplaced at the base of the volcano. The current Damavand cone is located above the old and eroded building and periodically includes trachyandesite- trachyte lavas with small eruptions of mafic lavas and pyroclastic rock. These lavas formed in the youngest geological period (Quaternary) covered Mesozoic deposits (Shemshak and Lar Formations). The intensity of Alborz volcanic activities extended into the Tertiary, but was not uniform, as its maximum occurred in the late Eocene and Oligocene, and after a period, volcanic activities re-intensified in the Pliocene.Regional GeologyDamavand volcano is in the center of Alborz Mountain Belt, in the Iranian plateau. The stratigraphic evidence indicates that the volcanism occurred in the two phases the older (old Damavand) and the younger sequences (younger Damavand)Analytical MethodsAfter initial petrographic studies, suitable samples were analyzed for whole-rock composition determined by XRF and ICP-MS analyses at the Geological Survey of Iran.Mineral composition determined by EPMA (Electron Probe Micro-Analyser) at Iran Mineral Processing Research Center. The analysis was performed at this center 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.Petrography, Minerals, and Whole Rocks ChemistryThe analyzed samples roughly cluster in the two zones, mafic alkaline rocks (tephrite-basanite) and intermediate-felsic rocks (trachyandesite- trachyte). The main purpose of this study is the mineral chemistry of the Ziar-Lasen trachyandesites, with a SiO2 content of 57wt%. The predominant mineral assemblages of these rocks are plagioclases (andesine-Labradorite), k-feldspar (sanidine-anorthoclase), clinopyroxene (augite-diopside), mica (phlogopite, biotite), apatite, and Ti-magnetite and the dominant textures are porphyry and microlithic porphyry textures with main phenocrysts. Feldspars show signs of disequilibrium and sieve textures in their cores and rim and desorption and skeletal. These phenocrysts, which are sometimes as glomerocrysts, show zoning Some mafic enclaves with variable textures and mineralogy are seen in the matrix of the trachyandesitic rocks.Result and Discussion Volcanic activities in the middle part of Central Alborz Mountain initiated about 2 million years ago with the eruption of mafic to intermediate-acidic lavas and pyroclastic rocks. The most common minerals of the trachyandesits from the south of Damavand (Polour to Ziar-Lasem) are felspar, pyroxene, mica, apatite, and opaque minerals., whereas the intermediate lavas are characterized by the presence of plagioclases (An31-58, andesine), alkali feldspars (Or32-65, sanidine to anorthoclase), pyroxene, mostly augite (Wo42-45 En42-47Fs10-13) rare diopside (Wo46-48 En43-46 Fs8-10), mica phlogopite (Fe2+/(Fe2++Mg) <0.3) as well as high Mg # (67-76) and Ti-magnetite.Chemically, the clinopyroxenes are characterized by high Mg # (97-76) and phlogopites by Fe # <0.33, high Ti (70-79), and high Mg # (76-67) and so, the nature of host magma is sub-alkaline.On the base of thermobarometer data, the clinopyroxene and phlogopite phenocrysts from Ziar-Lasem trachyandesites crystallized at a wide range of temperature and pressure.The crystallization temperature for clinopyroxenes, ranges from 1180 to 1250 °C, at 6-10 kbars pressure (equi. to 22-36.5 km depth), and for mica varies from 819 to 843°C, at 0.1-1.14 kbars pressure (equal to 4-0.65 km depth.). Base on clinopyroxenes compositions (Mg#>80) the crystallization of these minerals was re-equilibrated with high Mg# melts (50–54) (Eskandari et al., 2018). The similarity of these values with those of basalts indicate their deep crystallization from more mafic magma (Lanzafame et al., 2013). It is suggested that the clinopyroxenes of the intermediate volcanic products of Ziar-Lasen were crystallized at 22-36.5 km depth, approximately equivalent to lower crust (28–33 km), and evolved by assimilation, fractionation, and contamination when their parent magma erupted from deep depth to the surface or crystallized at shallow chambers within a thick crust.AcknowledgmentThe author is grateful to the Editor-in-Chief and esteemed referees of the Petrological Journal for their useful constructive comments, to the Research Institute for Earth Sciences and to Dr. Karimi.

The Cheshme-Bid Granitoids is located in SE Zahedan, Sistan and Balouchestan P Province. These granitoids are in Middle Eocene Neh metamorphosed flysch zone. The main minerals in these granites are quartz, plagioclase, biotite and amphiboles. Based on microprobe analysis, amphiboles are calcic in composition and set on magnesio-hornblende and actinolite classes. Based on chemical classification of micas, these minerals are located between siderophyllite and biotite. The Fe/ (Fe+Mg)>0.33 ratio shows that mica minerals are biotites and they are separated from phlogopites. The composition of plagioclase is between 19.56 to 32.51 an and the average of anorthite is 23.78 %. Estimated pressure and temperature for the formation of the granitoid, based on Al- Barometry in hornblendes, is about 3.8 Kb and the temperature is relatively low, about 751 celsius degree in granodiorite.