Dardvey iron skarn ore deposit is located in the central part of the Sangan mininig area, northeastern Iran. In this study, silicate geothermometr were used to estimate the formation temperatures of skarn zones in Dardvey Fe-skarn deposits. The main metamorphic minerals in prograde and retrograde skarn zones are garnet-clinopyroxene-tremolite/actinolite-amphibole-chlorite-epidote-feldspar-phlogopite-dolomite. Two feldspar Geothermometry indicate that endoskarn zone in Sarnowsar granite form at temperatures between 635 to 725 ° C, which is not consistent with fluid inclusion tempertures. Based on clinopyroxene-garnet Geothermometry, temperature of 300 to 505 ˚ C was calculated for prograde skarn stage. Chlorite and Ca-amphibole Geothermometry of retrograde zone indicates temperature of 200 to 290 ° C and 200 to 300 ° C respectively. Silicate minerals Geothermometry of prograde and retrograde skarn zones are in accordance with fluid inclusion data. Both geothermometery methodes of prograde and retrograde skarn zones indicate that contact metamorphic sakarn development occuured in <600 ˚ C that is consistent with hornblende hornfels facies.

One of the metamorphic rocks in the Nain ophiolitic melange is skarn which is formed during the contact metamorphism of intrusive tonalites with their neighboring limestone’s and carbonate parts of banded cherts. Minerals of these skarns consist of carbonate (calcite), clinopyroxene (diopside), garnet (grossular-andradite), wollastonite, sphene and epidote.Also tonalites contain quartz, plagioclase (albite), alkali feldspar (orthoclase), garnet (almandine-spessartine) and prehnite. Based on mineral assemblages of Nain skarns as well as Geothermometry of feldspars existing in relevant granites and also applications of different calibrations of garnet clinopyroxene geothermometer, the Nain skarns form at temperatures of about 440 to 650°C at low pressure during a contact metamorphism which has occurred at hornblende hornfels to pyroxene hornfels facies.

The chemical composition of chlorite group minerals show that physicochemical condition of crystallization and their formation. The chemical analysis of chlorite from biotite alteration has done based on 30 points of 8 rock samples by electron microprobe. The composition of chlorite samples is located in repidolite-pychnochlorite domain. The mole fraction in the interlayer phase, range from 0. 97 to 0. 99, indicating a complete lack of smectite layers and purity of chlorite. Calculation of the structural formula of chlorites in Malvak area show that the number of silicon atoms are in the range of 2. 64 to 2. 91 (apfu) and the sum of the octahedral cations are 6 (apfu). Chlorites of the Malvak area are trioctahedral type. The low titanium content of chlorites, the presence of titanium minerals coexite with chlorite cleavage, and the presence of early biotite crystals are evidence of biotite to chlorite alteration. The mean temperature of chlorites in the Malvak area is 340 º C, which corresponds to the temperature obtained with the Geothermometry of biotite-altered to chlorites. Mesothermal type fluids from the granitoid mass in the study area have been effective in chlorite occurrence. Also, regional metamorphism has played an important role in the chlorite formation.

Geochemical studies of the Pinavand Fluorite Mines indicates that fluorite has been deposited from a high salinity, typically low temperature and Mg-rich fluid in two stages: Based on geothermometrical data, at the first stage fluorites were formed at relatively high temperature (85-235Co) and accompanied by host rock replacement (in the form of epigenetic dolomitization). The second stage of fluorite mineralization has occurred at low temperature (65-115oC) and has formed lodes and vein-likes along the breccia and fault zones. However, the salinity was relatively invariable (15-23 wt% NaCl), suggesting salinity of fluorite-forming fluid was the same at all occurrences. By studying of REE patterns and regarding to some ratios of HREE to LREE, it could be observed that the first stage of fluorites was enriched in LREE revealing mineralization has occurred in early stage of crystallization .In contrast, the second stage of fluorites containing high proportion of HREE were deposited in the last stages of crystallization event. Based on the calculated (Yb/La), (Yb/Ca), (Tb/La) and (Tb/Ca) ratios, two mechanisms could be proposed: assimilation (replacement) for the first type fluorites and remobilization (rejuvinilization) for fluorites of the second stage.

The aim of this study is to investigate the hydrogeochemical characteristics of hot water springs of Khoy-Maku geothermal field, the effect of different rocks, the role of hydrothermal fluids on increasing the concentration of ions and elements in springs and estimating the reservoir equilibrium temperature. For this purpose, water samples were taken from hot and cold springs in september 2018. The results show that this water is confined and shallow and in them a water type is Na-HCO3. In springs Na and HCO3 are 736 and 2122 mg/l, respectively. Results of ion ratios, hydrogeochemical diagrams show that the high concentration of ions in the water are related to the effect of host rocks and ion exchange. Hot water springs have high Na, HCO3, and As and B are 1. 47 and 0. 7 mg/l, respectively. There are no evaporative rocks in the study area, therefore, the source of ions cannot be only attributed to the effect of rocks. Due to the presence of heat magmatic bodies in the depths, the high concentration of some elements, can be related to their separation from magmatic and hydrothermal systems. According Na-K-Mg diagram the thermal waters were immature waters. Therefore, the use of cation geothermometers to estimate the depth temperature of the geothermal reservoir in the region between 22 to 667 °, C, can not be accurate enough. Based on silica geothermometers, mineral saturation index and enthalpy–, silica mixing model, reservoir temperature was not very high and estimated in the range of 70 to 78°, C.

The Quaternary basaltic rocks of north Siriz, located in the northwest of Zarand, are part of the volcanic rocks of Central Iran structural zone. Mineralogically, they consist of olivine, clinopyroxene and plagioclase phenocrysts and porphyritic is the main texture. Furthermore, they are characterized by microlitic-porphyritic, gelomero porphyritic, trachytic, intergranular, intersertal and amygdaloidal textures. Based on the electron probe microanalysis (EPMA), the olivine, clinopyroxene and plagio-clase phenocrysts are chrysolite, augite and anorthite in composition, respectively. Also, changes of chemical composition of magma are insignificant during crystallization of the phenocrysts, as MgO contents of olivine phenocrysts are slightly decreased from core to the rim. However, TiO2, and MgO and SiO2 contents of clinopyroxene phenocrysts show increasing and decreasing trends toward the rim, respectively. Based on thermometric studies, the temperatures between 1212 to 1283oC are estimated for the formation of clinopyroxene crystals.

The Jouzbon Cu index (~1. 5 wide and 100 meters’ length), at the south-southeastern parts of Damghan city belongs to the Torud– Chah Shirin volcanic belt. This belt contains calc-alkaline volcanic rocks. The Cu mineralization has occurred between two major faults, the Torud Fault at south and the Anjilu Fault at north. The volcanic and intrusive rocks in this belt include quartz-diorites, quartz-monzonites, dacites and andesites. These rocks show porphyritic, granular and poikilitic textures. The prevailing alteration phases of this region are characterized by sericitization, silicification, calcification, and propylitic alteration. The main mineralization phases of the Jouzbon region are dominanted by occurrence of the sulfides and oxide minerals including pyrite, chalcopyrite, galena, bornite and hematite. Secondary minerals such as covellite, chalcocite, malachite and iron hydroxide are also common. Geochemical observations show that the host rocks are related to a alumina-saturated calc-alkaline magma with volcanic arc (VAG) signature. Fluid inclusion studies on quartz testified a narrow homogenization temperature but a wide salinity, ranging from 130 to 190 ° C and 4 to 14. 5 wt% NaCl equivqlent respectively. Geothermometry assay, based on morphology of pyrite crystals, yielded a temperature in the range of ~250° C for the alteration zone. The compiled data testified that mineralization probably has occurred at the depth of ~ 100 meters below the surface during the epithermal conditions, similar to the IOCG-type deposits.

The Mn, Fe, Ni, Co, Cu, Pb, Ga, Ge, Cd, Sn and Ag contents of 10 sphalerite samples from the Emarat Zn-Pb deposit were determined. The principal trace elements are Fe, Cd, Pb, and Mn. The Fe content of the sphalerite ranges from 11580 to 21700 ppm, the Cd content from 452 to 549 ppm, the Pb content from 652 to 5186 ppm, and the Mn content from <2 to 497 ppm. The Ni, Co, Cu, Ga, Ge, Sn, and Ag contents are low. Trace element geochemistry of sphalerite from the Emarat deposit compares well to literature data reported for classical Mississippi Valley-type (MVT) districts in the world. The Ga/Ge geothermometer indicates a temperature range of 175°C to 235°C for the ore-bearing fluid. This temperature range is consistent again with the ore formation temperatures for MVT deposits. Accordingly, the Emarat Zn-Pb deposit must be classified as an MVT deposit.

In the southeast of Iran, titaniferous magnetite deposits associated with the gabbro rocks occur in Kahnuj ophiolitic complex. Mineraloghraphy studies have revealed the primary and secondary ore mineral consist of titanomagnetite, ilmenite, hematite, goethite, martite, pyrite, chalcopyrite, pyrrhotite and silicate minerals (plagioclase, pyroxene, hornblende, olivine, alkali feldspar). Trellis-sandwich textures and ilmenite-titanomagnetite intergrowths are resulted from oxidation of former Ti-rich magnetite at different temperatures. Chemical analyses show that the ilmenite and magnetite (titanomagnetite) contains 46. 51 to 52. 68 and 4. 00 to 19. 71 wt. % TiO2 and 1. 00 to 2. 98 and 0. 00 to 1. 74 wt. % V2O3, respectively. The ulvö spinel (Mol % Usp) (Fe2TiO4) in titanomagnetite shows a composition ranging from 4. 58 to 56. 87 wt. %, and ilmenite lamellae are varying thickness and ilmenite type 1 to 3 contain of 88. 23 to 93. 94, 93. 04 to 99. 80 and 99. 09 to 99. 73 wt. % of the ilmenite (Mol % Ilm), respectively. Compositions of intergrowth Tm-Ilm pairs (type 2) were plotted on T/fO2 diagrams. The Tm-Ilm pairs show varying degrees of re-equilibration to subsolidus temperatures (551 to 830° C) and fO2 (-21. 6 to-23. 97). The Tm-Ilm pairs from Dar Gaz cluster around the QFM buffer curve for 1. 5 kbar total pressure.

Chloritoid is crystallised with chlorite, white mica and garnet in chlorite zone metapelites of the regional metamorphic rocks of the Sanandaj-Sirjan metamorphic belt in southern Iran. Chemistry of coexisting minerals is studied using microprobe analysis. Application of the chlorite-chloritoid Geothermometry gives temperatures of 515°C and 557°C. The Chlorite-garnet Fe-Mg exchange geothermometer indicates temperatures between 442°C and 460°C for various pressures. A comparison of the results from two geothermometers, along with a study of mineral assemblages in the rocks show that the chlorite-chloritoid thermometer overestimates the temperature by about 70°C.