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The study area lies in the south of Mamoniyeh, a part of the Zaviyeh 1:100000 geological map, which covers the middle part of the Urumieh-Dokhtar magmatic arc. The volcanic phases and the intrusive masses constitute the predominant rocks of the area which has been subjected to magmatic and tectonic activities. Thus, owing to the lack of detailed studies on the volcanic rocks of this area, we try to link the tectonic setting and the magmatic evolution of the rocks under study. In addition, magma evolution processes, such as fractional crystallization, crustal contamination, and magma mixing may play an important role in the genesis of these rocks. The present paper presents new petrological and geochemical data on these volcanic rocks, which were formed during the Eocene. The Urumieh Dokhtar Magmatic arc is characterized by a series of volcanic and plutonic rocks that formed during the Late Cretaceous to Early Miocene, approximately 95 to 20 million years ago, and extends for about 2,000 kilometers. [ABSTRACT FROM AUTHOR]

Mineral chemistry data as well as petrography provide a comprehensive picture of magma crystallization conditions that support the conclusions based on geochemical data. In addition, the chemical composition of minerals such as clinopyroxene, olivine, biotite, feldspar, and Fe-Ti oxides reflect physicochemical parameters (pressure, temperature, and oxygen fugacity), crystal growth history, and melt origin. The pressure, temperature and oxygen fugacity parameters are estimated from chemical data of various rock-forming minerals to provide information regarding the crystallization of magmas. The essential purposes of present study are to determine the physicochemical conditions (temperature and pressure), to identify the tectonic environment and to propose an emplacement model for Pargeh mafic magmas formation. [ABSTRACT FROM AUTHOR]

Naqadeh intrusive pluton is composed of two distinct sections of felsic (40 Ma age) and mafic (99 Ma age) rocks. The granitoid rocks of Naqadeh pluton have different types of mafic enclaves, including mafic microgranular enclaves (MME) and quartz + amphibole bearing enclaves. The MME has the same age to its host granitoids and could be divided into two types. The first type has similar Sr-Nd composition to the host rock (87Sr/86Sri = 0.7062 and εNdi= -0.89), and their trace amphibole composition is like host granitoids. These enclaves are cogenetic with the granitoid magma and formed by early crystal-melt segregations. Another type of MME shows the textural evidence of magma mixing and is characterized by different isotopic ratios from granitoids (87Sr/86Sri = 0.7042 and εNdi= +2.98). The trace element composition of this type of enclave is completely different from the other enclaves and the host rocks. The quartz + amphibole bearing enclave formed contemporaneous with mafic rocks of Naqadeh pluton (99 Ma), and displays the same isotopic ratios and amphibole composition. [ABSTRACT FROM AUTHOR]

The Meshkin-Rasht Abad area is a small part of the western Alborz-Azarbaijan magmatic belt (AAMB). Field investigations reveal that andesitic-basalt rocks are the dominant rock units of the area with high-K calc-alkaline to shoshonitic affinities. On the basis of geochemical features all rocks are enriched in light rare earth elements (LREE), large ion lithophile elements (LILE) and have positive anomalies of Pb, U and Cs and Ti, Sr and Nb negative anomalies. These volcanic rocks have the criteria of active continental margin arcs on tectonomagmatic discrimination diagrams. Geochemical data, including low amounts of Cr, Ni, V, and Zr/Nb ratio suggest the enriched mantle source (lithospheric mantle) for the rocks under study. Moreover, the diagrams of the ratio of highly incompatible elements indicate the effect of slab-derived fluids on the magma generation. The Ce/Pb low value as well as various geochemical diagrams demonstrate that the magma is possibly contaminated by continental derived crustal materials. [ABSTRACT FROM AUTHOR]

Magmatic evolution, partial melting and petrogenesis of the basaltic rocks from Marivan-Palangan ophiolite suite, Zagros suture zone, western Iran have been studied. Basaltic rocks mostly exhibit pillow structures and have remarkable outcrops in the crustal succession of the Marivan-Palangan ophiolite. Based on petrographic and geochemical criteria, two distinct rock types are recognized. Regarding the chemical classifications, both types are basalt. The results of CIPW norm calculations reveal their olivine tholeiitic (abyssal tholeiitic) nature. They also belong to the tholeiitic magma series close to the transitional type. The high Ti contents of the basalts are indicative of the High-Ti affinity of the ophiolites. Fractionation of variable amounts of olivine, plagioclase and clinopyroxene is inferred from variation diagrams, particularly for the type two rocks. Although both rock types resemble the E-MORB on the multi-element diagrams, they are remarkably distinct regarding the HREE and MREE contents. Partial melting models suggest that the basalts have been originated after 5-25% (type 1) and 15-25% (type 2) partial melting of a spinel lherzolite mantle source. Besides, Sm/Nd, Ce/Sm, Sm/Yb and La/Yb ratios of the samples are close to an EMII-type enriched mantle; that may be indicative of contribution of EMII-type components to the petrogenesis of the magmas. It is concluded in this research that variable degrees of partial melting of a spinel peridotite mantle source, combined with the contribution of EMII-type components generated the enriched nature of the ophiolite-related basalts in this part of the Neo-Tethyan realm. [ABSTRACT FROM AUTHOR]

The Sahand volcano is located in the NW of Iran. The volcano is stratovolcano and is dominated by pyroclastic materials and lava flows in the Miocene-Quaternary. The last eruptions included subvolcanic and volcanic domes with dacitic to rhyolitic composition, which are studied in this paper as the young Sahand. These rocks have petrological features including sieve texture and zoning in plagioclases. Common features in the young subvolcanic and volcanic rocks of the Sahand are abundance of plagioclase and amphibole, enrichment of Ba, Rb and Sr and negative Nb and Y anomalies in primitive mantle normalized multi element diagrams and enrichment of LREE relative to HREE in chondrite-normalized REE patterns. These characteristics and the location of the rocks studied in the Y-Sr/Y diagram implying adakitic composition for these rocks. Adakitic rocks of the young Sahand are high SiO2 Adakitic rocks. These rocks have been derived from partial melts of garnet-bearing crustal sources (thickened lower continental crust or oceanic crust) and underwent magmatic evolution during their ascent. The formation of the studied rocks have been related to the Arabian-Eurasia collision zone. [ABSTRACT FROM AUTHOR]

One of the characteristics of the Ordovician to the Devonian rock units in the north of Shahrood is the presence of high volumes of igneous rocks with basaltic composition as dyke and sill. The greatest volume of these rocks are widespread in Soltan Meydan Basaltic Complex with a thickness of about 1000 m as numerous basaltic lava flows, basaltic agglomerates, tuffs and some sedimentary intercalations which have been formed during the upper Ordovician to the early late Silurian. Active extensional tectonic prevailing on the area and violent detaching in continental lithosphere in this interval time led to sudden decompression on the rising mantle plumes, providing conditions for extensive partial melting and generation of high volumes of basaltic magma. Geochemical evidences show that the produced magmas have transitional to alkaline nature and generated from a rising enriched mantle plume source in an extensional intracontinental rift setting. The nature and tectonic setting of this basaltic magmatism during the lower-middle Paleozoic indicate continuation of long lived extensional movements related to the earlier stages of Paleotethys rifting in the north of Iran. [ABSTRACT FROM AUTHOR]

The studied volcanic rocks, in the middle part of the Central Iranian volcanic belt (Urumieh-Dokhtar magmatic arc) belong to a vast magmatic province located in the north of the Bitlis-Zagros suture zone. Petrographically, these rocks show dacite to andesite composition and include phenocrysts of plagioclase, amphibole and biotite with a prevailing porphyritic texture in a matrix composing of feldspar, quartz, microlite and glass. Having a relatively invariable composition, plagioclases are all andesine. Amphiboles are calcic and tschermakite type. Estimation of temperature and pressure of crystallization resulted from graphically integrating amphibole and amphibole-plagioclase geothermo-barometry equations indicates that the amphibole-plagioclase phenocrysts were crystallized in the temperature range of 763-823 °C with average of 797 °C and in the pressure range of 2.2-4.5 kbar with the average of 3.4 kbar. The maximum depth of crystallization is evaluated at 17 km in continental crust. [ABSTRACT FROM AUTHOR]

The Sungun porphyry copper mine is located in the north of Varzeghan, Eastern- Azarbaijan province. The oldest rocks in the study area are limestone with the Cretaceous in age. Following the emplacement of intrusive porphyry body, four groups of dyke with various compositions have been intruded into the intrusive body. The intrusive is quartz- monzonitic in composition. There are four alteration zones including potassic, phyllic, propylitic and argillic in the Sungun porphyry body. The common texture in these rocks is porphyritic with cryptocrystalline matrix, and in dykes, microlitic and microlitic porphyry. The Sungun porphyry body evolved due to magmatic differentiation, fractional crystallization, assimilation and crustal contamination. The Sungun intrusive and associated dykes are meta-aluminous and belong to high-K calc-alkaline to shoshonitic magma series. In terms of tectonic setting, the Sungun body lies in syn- to post-collision volcanic arc. In the contact of the Sungun porphyry and the upper Cretceous limestones and marls, the Cu-Fe skarn developed in the north and the east. These skarns are divided into the endoskarn and exoskarn. Based on field geology and mineralogical studies, the exoskarn in Sungun is divided into pyroxene, garnet and epidote zones. [ABSTRACT FROM AUTHOR]

The Khezr-Abad granitoid intrusive body is located in the north-west of Yazd province within Urumia-Dokhtar magmatic arc. The intrusion of this body into the Cretaceous carbonate rocks (Taft Formation), gave rise to Hasht-kuh skarn mineralization with the following mineral assemblage: Garnet+ Clinopyroxene+Epidote+Tremolite-Actinolite+Chlorite+Calcite+Quartz Mineral associations studies show that pyroxene-garnet occurrence have most relations and are widespread in skarn. A detailed study of paragenetic relationships of skarn minerals clearly demonstrate that there are two stages in skarn evolution system, so the Hasht-kuh skarn can be considered as a polygenic skarn. On the basis of mineral chemistry data the garnet tends to be grossular and pyroxene is augite in composition. The peak temperature of contact metamorphism episode is accompanied by pyroxene crystallization in the early stage followed by overprinting of garnet formation. Due to presence of Al/Fe+3 periodic changes in fluids during garnet precipitation, zoning structure in some garnets was developed. The prevailing oxidation conditions during crystallization of fluids caused the instability of pyroxene (reducing fO2) and the growth of andradite garnet could be occurred at T<550°C in skarn system. [ABSTRACT FROM AUTHOR]

The Nash's Tertiary volcanic rocks in the Alborz Mountains in the east of Roudbar (North of Iran) show a compositional range from olivine basalt, basaltic andesite, pyroxene-andesite to andesite. From petrographical point of view, the diversity of xenoliths and xenocrysts are evidences for crustal contamination. The positive correlation of CaO/Al2O3 vs. MgO and Al2O3/CaO vs. SiO2 are signatures of differentiation of olivine and clinopyroxene in magmatic evolution. The positive correlations of K2O/P2O5 vs. SiO2 and La/Sm vs. K2O/P2O5 indicate the contamination of magma with continental crust. The incompatible elements patterns and their comparison with those of continental crust point to the contamination of volcanic rocks with lower and upper continental crust. The linear trends on Zr/Y vs. Nb/Y diagram, indicate two different sources for the studied rocks. The MORB-mantle source and the continental crust. The variations of Zr/Nb vs. Y/Nb and Rb/Y vs. Nb/Y display the crustal contamination of magmas which are derived from MORB-mantle source. Geochemical studies show that the studied rocks were originated from 15% melting of a MORB source in spinel facies in continental within-plate. [ABSTRACT FROM AUTHOR]