جستجوی مقالات مرتبط با کلیدواژه "سنگ‏ ‏ های آتشفشانی" در نشریات گروه "زمین شناسی"

The study area is situated 21 km SW of Ardestan city and 80 km NE of Esfahan (Central Iran). and according to the sedimentary structural divisions (Fig. 1; Aghanabati, 1998) in the central part of Urumieh-Dokhtar Magmatic Belt (UDMB) The UDMB in the Alpine-Himalayan orogenic belt, the most productive metallic belt of Iran, composed of basic to acidic volcanic and plutonic rocks, tuff and agglomerate. The UDMB represents geochemical characteristics of subduction zones with features of calc-alkaline locally toward alkaline (Berberian and Berberian, 1981; Alavi, 1994; Shahabpour, 2007; Omrani et al., 2008; Ghorbani and Bezenjani, 2011; Yeganehfar, 2013; Rajabpour et al., 2017). The UDMB hosts several porphyry Cu±Mo±Au deposits including Sungun, Sarcheshmeh, Kahang, Darehzar, Nowchun and Meiduk (Atapour and Aftabi, 2007; Zarasvandi et al., 2015; Zamanian et al., 2016; Alirezaei et al., 2017; Jamali, 2017) and associated porphyry copper-gold, gold epithermal and manganese-iron deposits (Rajabpour et al., 2017; Ostadhosseini et al., 2018; Alaminia et al., 2020; Ostadhosseini et al., 2021). Different stages of Cenozoic magmatic activity in the middle segment of the UDMB around the study area consist of different successions of volcanic and intrusive rocks (Radfar, 1998). The Eocene to Miocene diorite- monzodiorite bodies were intruded the Eocene volcanic and subvolcanic rocks. In the middle of the area, these intrusive units are juxtaposed with a fault boundary (Marbin fault) adjacent to Eocene volcanic units. 
 
The Eocene volcanic stage is dominated by basalt, andesitic basalt, andesite, tuffs and ignimbrites rocks. Quaternary sediments are widespread in the northeastern and southern parts of the area. The oldest rock unit of this area is the Shotori dolomite formation trending NW-SW and belonging to Triassic age and located in the southwest of the study area. Cu mineralization occurs within the Eocene volcano-sedimentary sequence. The purpose of this study is to determine the type of Cu mineralization based on the mineralization characteristics, geometry, texture, structure and alteration studies, as well as the geochemistry and tectonic environment of the host volcanic rock.
For the purposes of this study, 60 thin sections of volcanic rocks and 30 polished thin sections of ore samples were studied by a standard petrographic microscope under reflected and transmitted lights. 10 surface and drill–holes samples from volcanic rocks were crushed and powdered in tungsten carbide swing mill for whole-rock analysis. The chemical analyses were performed for the major elements using X-ray fluorescence (XRF) and trace elements using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Electron microprobe analyses were performed, using a JXA-8100 electron microprobe. Operating conditions were 35 kV accelerating voltage, a beam current of 20 nA, and a beam diameter of 2-10 μm.
All the petrographic studies as well as chemical analyses including XRF, ICP-MS and EPMA were carried out at the Seoul National University Laboratories, Seoul, South Korean.
The dominant rocks of the area under study are basalt, basaltic andesite, andesite and a small volume of pyroclastic rocks which are metaluminous composition and calc-alkaline affinity. Geochemically, they are enriched in LREE relative to HREE, enrichment of LILE and negative anomalies of HFSE (i.e., Nb, Ti), pointing to characteristics of subduction-related magmatic possibly generated by partial melting of metasomatized lithospheric mantle source. As the discrimination diagrams of tectonic setting display, the volcanic rocks are also classified as a subduction-related magmatic arc. Alteration zones were developed in the rock types including silicic, propylitic, argillic, sericitic and zeolitic. The propylitic and silicic alterations were extended within the mineralized zones. The propylitic alteration is the dominant alteration consisting mainly epidote, chlorite, and calcite. The silicification zone consists of crystalline quartz-formation, which occurs as veins and veinlets including some copper minerals. The carbonate alteration is observed in basaltic andesite and andesite rocks. Copper mineralization is mainly strata-bound, and occurs partially as veins, veinlets and disseminated in the andesite, basaltic andesites, and basaltic rocks. Based on microscopic studies, three mineralization stages were recognized in the Rahimabad deposit including pre-mineralization, mineralization, and post-mineralization stages. In the pre-mineralization stage, pyrite is formed in decreasing conditions in the host rock. In the main mineralization stage, pyrite is replaced by primary Cu and Ag sulfide minerals such as chalcopyrite, bornite, chalcocite, digenite, jalpaite and acanthite. Finally, in the post mineralization stage, copper sulfide minerals are replaced by secondary copper sulfide minerals (chalcocite, covellite and digenite) and oxide minerals (malachite, azurite, goethite and hematite).
The Rahimabad Cu (Ag) deposit lies in the SW of the Ardestan city in the Urumieh-Dokhtar Magmatic Belts, Central Iran. In this area, Cu and Ag mineralization is observed in the volcano-sedimentary rocks. The copper (Ag) mineralization occurs in andesite, basaltic andesite and basaltic lavas. These rocks are meta-aluminous and have a calc-alkaline affinity and indicate a subduction-related magmatic arc. The main alterations zones are silicic, propylitic, argillic, sericitic and zeolitic. The geometry of mineralization is strata-bound and the texture and structure of mineralization is open space filling, disseminated, vein-veinlet and replacement. Based on microscopic as well as EPMA data, the most important Cu and Ag minerals include chalcopyrite, bornite, chalcocite- covellite group minerals, malachite, azurite, acanthite and jalpaite, which are accompanied by magnetite and hematite. Pyrite is mostly observed as a separate mineral in the host rock. The overall mineralization characteristics and tectonic setting, the type of host rock, geometry, texture and structure, mineralogy and the paragenetic of Cu minerals and finally the alteration zones with different types of copper deposits document that the Rahimabad copper deposit share many features with those of Manto type copper deposits.
Acknowledgment
The present study was financially supported by the Cu-Au company of Ardestan. The authors are grateful to Mr. Sharif for providing sampling facilities and let us access to drill cores and exploration data.

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 study area is located in the south of Damghan, 160 km south of Shahrood, and 17 to 30 km south of Torud village. The area geologically, lies in the Cenozoic magmatic belt, a part of the Alpine-Himalayan belt, in the north of the structural zone of Central Iran (Aghanabati, 2004). The Cenozoic magmatic belt has been studied by many researchers (e.g., Ghorbani, 2005; Khajehzadeh, 2009; Mardani-Beldaji, 2011; Tayefi, 2014; Yousefi, 2017). The volcanic rocks in the southern part of the Torud area have not been comprehensively studied. Therefore, it requires a detailed study. So, for the purpose of this study attempt has been made to investigate and to study the nature of magma, tectonic setting, and the petrogenesis of the volcanic rocks using the geochemical data of the whole rock. Also, the results of this study have been compared with some areas belonging to the Cenozoic Era located in the north of the structural zone of Central Iran.

Regional Geology:

The area under study in the Torud-Moalleman magmatic belt belongs to the Chah-Shirin-Sabzevar-Khaf magmatic complex, located in the western part of this magmatic complex. In this magmatic belt, the Eocene volcanic rocks, including the main volume of igneous rocks are basic to acidic in composition. The predominant rocks are basaltic to intermediate rocks. The Torud-Moalleman magmatic belt is mainly composed of volcanic rocks with a lithological composition consisting of olivine-basalt, basalt, andesite, and dacite rocks and their pyroclastic equivalents, as well as plastic and limestone interlayers.

During field surveying, 50 samples of the volcanic rocks with the least alteration were collected. From these samples, 30 thin sections were prepared for microscopic studies and 11 samples were selected for ICP-MS geochemical analyses for minor elements and XRF for major elements and were sent to ACME Laboratory in Vancouver (Canada). GCDkit, Excel, and Corel Draw software were used to check the results obtained from the whole rock chemistry analyses and drawing diagrams.

Petrography:

The study rocks include volcanic rocks ranging from andesite to basalt. The basalts are dark gray to black in color with glomeroporphyritic, microlithic, sieve, and trachytic textures containing plagioclase and clinopyroxene as the main minerals. These minerals along with olivine and magnetite can also be seen in the form of microcrystals in the background of the rock, and their accumulation have created the glomeroporphyritic texture in these rocks. Secondary minerals are chlorite, iron oxide, zeolite (natrolite and analcime), calcite, and gypsum, filling the holes.The andesites are light gray to slightly dark with porphyritic and glomeroporphyritic textures and are dominated by amphibole (green and brown hornblende), plagioclase, and clinopyroxene as the main, biotite, iron oxide, sphene, and zircon. as the minor, as well as sericite, chlorite, calcite, and epidote as the secondary minerals.

Whole Rocks Chemistry :

The data obtained from the whole rock geochemical analyses display that the volcanic samples of the Torud area are classified as the andesite and basalt, placed mostly in the range of calc-alkaline series (medium potassium). LREE and LILE enrichment, HREE and HFSE depletion and Nb, Ta, and Ti negative anomalies of these rocks point to their formation in subduction zones. Also, as the tectonic diagrams display the rocks belong to the active continental margin. The rocks under study have mostly mantle origin and are derived from an enriched lithospheric mantle. The flat HREE patterns also show that melting occurred in the mantle, above the stability field of garnet. Therefore, the parent magmas were formed by the melting of spinel lherzolite at a depth of 80 to 100 km and evolved due to fractional crystallization as well as contamination caused by subducted sediments and the continental crust.

The rare elements pattern of the study rocks in spider diagrams show the cogenesis of these rocks and the role of differential crystallization as the main mechanism of their formation. Based on geochemical data, the study samples and compared volcanic rocks share similar characteristics. Therefore, the normalized REE patterns with chondrite (Nakamura, 1974) NMORB (Sun and McDonough, 1989) and MORB (Pearce, 1983), indicate the enrichment of LREEs (such as La, Ce) and LILEs (e.g., Ba, K, U, Pb, Cs) compared to HREEs and HFSEs (i.e. Nb, Ta, Ti, P) indicating that the rocks under study were formed in the active continental arc margin. The samples have no negative anomaly of Eu. Volcanic rocks with the age of late Eocene and Oligo-Miocene and basaltic to trachy-basaltic composition range from alkaline to sub-alkaline rocks and volcanic rocks with the age of middle Eocene with andesite to trachy-andesite composition have the nature of calc-alkaline.

The volcanic rocks in the south of Torud, with calc-alkaline and medium potassium nature, are mainly composed of basalt and andesite characterized by LREE enrichment, negative Nb-Ta-Ti anomaly, and the high ratio of LILE/HFSE. These characteristics point to the formation of these rocks in the subduction zones.The rocks under investigation have low SiO2 content, high amounts of Sr, no significant Eu anomaly, and Mg# content greater than 40. These geochemical features indicate a mantle source for the studied volcanic rocks. The changes of Rb/Y versus Nb/Y show the enrichment by subduction components or crustal contamination in the magmatic evolution of these rocks. Based on the geochemical investigations, the productive magma originated from a spinel lherzolitic source at a depth of about 80 to 100 km; during the ascent of magma, as a result of fractional crystallization and contamination, the magma derived from the mantle has been enriched and gave rise to lithological diversity.

Marshoun area located 120Km Southeast of Zanjan, is a part of the Tarom-Hashtjin metallogenic-magmatic subzone within the Alborz-Azarbaijan zone. Similar to most parts of the Alborz-Azarbaijan zone, the Eocene-Oligocene volcanic and the intrusive rocks of this subzone were formed as a result of the Alpine orogenic phase, which has a close spatial and temporal relationship with metallic mineralization (Kouhestani et al., 2019). Several studies have been conducted on metallic mineralizations in different parts of the Tarom-Hashtjin subzone. The petrological studies carried out in this subzone are mainly focused on intrusive rocks (e.g., Seyed Qaraeini et al., 2020) and volcanic rocks' geochemical and petrological characteristics have been less considered. Marshoun area is composed of volcanic-sedimentary sequences which are hosts for Pb-Zn-Cu mineralization (Kouhestani et al., 2019). A detailed scientific study has not been done on the lithological sequence and their geochemical and petrological characteristics in the Marshoun area so far. In the present study, the lithological and geochemical characteristics including Sr, Nd, and Pb isotopic data, as well as the tectonomagmatic environment of the volcanic rocks of the area have been investigated.

During fieldwork, a 1:25000 geological map prepared from different lithological units of the area and over 30 samples were taken. Also, 17 thin sections for petrographical studies, 10 samples for chemical and 4 samples (2 andesites and 2 dacites) for iaoopic analyses. Chemical analyses (XRF and ICP–MS methods) were carried out at Zarazma Laboratory, Tehran, Iran., and isotopic studies (i.e. Nd, Sr, and Pb isotope studies at Institute of Geology and Geophysics, Chinese Academy of Geosciences, Beijing, China.

The predominant rock units in the Marshoun area are Eocene acidic tuffs, dacitic-rhyodacitic lava, and occasionally ignimbrite at the base and alternation of intermediate tuff with minor andesite and basaltic andesite intercalation in the top, along with some intrusive rocks with (Zajkan intrusion), and some gabbroic dykes.Zajkan intrusion including pyroxene quartz monzodiorite, quartz monzodiorite, and granodiorite composition intruded acidic volcano-sedimentary rocks with a total thickness of 930 meters can be divided into 9 parts.Volcanic rocks of the Marshoun area are classified as rhyolite, rhyodacite, dacite, andesite, basaltic andesite, and trachy-andesite with high-K calc-alkaline affinity. Dacitic-rhyodacitic rocks have porphyritic, flow, and spherolitic textures, composed of plagioclase, quartz, alkali feldspar, and mafic minerals (amphibole and biotite) set in a quartz-felspathic groundmass whereas, andesitic rocks show porphyritic, glomeroporphyritic, and amygdaloidal textures, composed of plagioclase and mafic minerals (amphibole and some pyroxene) set in a fine-grained and occasionally microlithic groundmass.All samples under study on primitive mantle normalized spider diagrams, have similar patterns indicative of their genetic relations. LILEs and HFSEs.negative anomalies are remarkable features of these rocks. Chondrite-normalized REE patterns demonstrate a relatively steep to low slope pattern with LREE enrichment and a high ratio of LREE/HREE, (La/Yb)N, and (La/Sm)N ratio between 3.8-30.1 and 1.2-8.25, respectively. On tectonomagmatic setting discrimination diagrams, volcanic rocks of the Marshoun area have been formed in an active continental margin tectonic setting. Isotopic data of Sr (0.70485-0.70622), Nd (0.512695-0.712733), and Pb (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb between 18.743-18.803, 15.5938-15.6112 and 38.8138-18.0721, respectively) point to dominant role of mantle in the formation of the investigated rocks. According to the Pb isotopes, the area's acidic rocks originated either from a more enriched mantle or were contaminated by crustal materials during ascending magma.

As the geochemical data indicate the primary magma of Marshoun volcanic rocks is generated by the partial melting of subcontinental metasomatized mantle lithosphere as a result of the subduction process within the continental margin environment. According to data obtained from the present study as well as the previous research, it can be concluded that the result of the subduction of the active continental margin and the shortening of the crust in Alborz during the Eocene gave rise to the thickening of continental crust and further led to the separation and subsidence of the lower part of the subcontinental lithospheric mantle (delamination).As a result of this event, the ascending of asthenosphere currents has led to an increase in the thermal gradient and partial melting of the subcontinental lithosphere and generation of basic magma which during ascending contaminated by crustal materials. Finally, the differentiation process led to the formation of intermediate and acidic rocks.

Azerbaijan Plateau is a part of the Alpine-Himalayan fold and orogeny belt, which is located in a compressional regime and between Talesh Mountains, south of Lesser Caucasus Mountain, east of Anatolia, north of Zagros Mountain. The studied area has located in the geographical longitudes of 47° to 48° and latitudes of 38° to 39° in East Azerbaijan province. There are wide ranges of Plio-Quaternary basalts and andesite basaltic in the sheet of 1.250000 Ahar. These rocks are gray to black in color. They also are formed of lava flows with scattered sometimes prismatic structures on the Paleocene andesitic lavas or conglomerate, siltstone and red marl Pliocene.

After the field investigations, we were taken 30 fresh and unaltered samples. Then, they were prepared as a thin section, then go undrer petrographic studies with a microscope in the laboratory.  Finally, we selected 10 samples were sent to the Amdel laboratory in the Australia for chemical analyses by ICP-MS, and OES.  Consequently, the results of whole rock chemical analysis data, were processed by GCD-KIT software. Then, all data were interpreted by geochemical conditions of all analyzed samples and also with their tectonic environment in the area.

The studied area is a part of the lesser Caucasus mountain range with high deformation and seismicity, which has located in a crustal convergence in the northwest of Iran. This area has a faulted system and with active strike-slip faults (Kocyigit et al., 2001). These systems often coincided with previous crustal discontinuities and have been widely effective in generating Quaternary magmatic activities locally through pull-part zones (Shabanian et al., 2012; Avagayan et al., 2010). Almost all the Quaternary magmatism in the region has occurred due to the operation of these fault systems and in the tensile position of the continental crust. Therefore, active fracture and fault systems and even old hidden faults have played a major role in the occurrence of the Quaternary magmatism.Volcanic rocks of the studied area are hyalo-aphanitic to hyalo-microlithic porphyry texture with large crystals of olivine, plagioclase and pyroxene. Also, porphyry, trachyte, intersertal and intergranular texture canbe seen in these samples. These samples have the nature of basaltic, thrachy andesite, mojearite and dacite, which are located in a calc-alkaline range. These rocks are rich in LREE and depleted in HREE.They also have enriched of Cs, Th, Pb and depletion of Ba, Nb, Eu, La. The presence of garnet in the source of magma can indicated the involvement of processes and crystallization of olivine, pyroxene, and plagioclase. In addition, metasomatism or contamination with enriched crustal materials (Menzies & Wass, 1983) leads to the abundance of LREE elements. Therefore, the metasomatized mantle can be a suitable origin for the magma of the studied volcanic rocks. Enrichment of elements Cs, Rb, Pb, Ba, LILE and depletion of elements HFSE (Nb, Zr) indicated the magma of subduction arc zones (Wilson, 1989). The negative anomaly of Nb, P, Ti, Zr and the positive anomaly of Pb are the characteristics of crust contamination of quaternary basalts (Wilson, 1989; Hofman, 1997). Negative Nb anomaly is characteristic of continental rocks and crustal involvement in magmatic processes (Hofman, 1997). Also, the negative anomaly of Ti and Nb in the normalized pattern with primary mantle composition can indicate magmas related to subduction (Pearce, 1983; Wilson, 1989). All the samples are in the range of intraplate basalts (Figure a10) (Mesched, 1986), and show the orogenic situation (Pearce et al., 1977). The studied volcanic samples are volcanic arc (Muller et al., 1992) belong to the continental arc after the collision (Groves, 1997).  Also, the studied samples show the origin of lherzolite garnet mantle and lherzolite spinel with a rate of 2 to 5% of partial melting.The tensile positions of the continental margins are active, where partial melting has occurred due to pressure reduction and rupture of the subcontinental lithosphere. Its compressive force resulting from crustal collision and crustal shortening, thickening and uplift leads to disturbance of subcontinental lithosphere thermal levels in these regions. Therefore, it seems that since the Eocene, the post-collision regime (Omrani et al., 2008) and since the Miocene (Hasanpour, 2008) has been ruling in the Arsbaran.

The Quaternary volcanic rocks in the eastern part of Ahar area, include a set of basaltic, andesite basaltic and andesite with calc-alkaline nature. The special depletion and enrichment of rare earth elements, these rocks are very similar to enriched mantle magmas and OIB, which were formed in the volcanic arc environment after impact on the active continental margin. For these samples, the mantle origin is lherzolite garnet to lherzolite spinel with 1 to 10% partial melting. Also there were happened metasomatisms of subducting oceanic lithosphere fluids. The geochemical evidences show some degrees of crustal contaminations during magma ascent. This magmatism has occured due to the subduction and the system of faults and fractures of the region and the tension tectonic situation. This tension system in the active continental margin after the collision has led to a decrease in pressure and finally the pouring out of basaltic magma.

The study area, situated 50 km north of Ghaemshahr, structurally belongs to the Central Alborz tectonic zone. The volcanic rocks of the area, including basalt, andesite, trachyandesite, and dolerite are the products of fractional crystallization and some contamination processes. Clinopyroxene, olivine, and plagioclase are the main minerals of these rocks. Porphyritic to mega-porphyritic texture with microlithic, glomeroporphyritic, and amygdaloidal matrix are observed in these rocks. Plagioclase, hornblende, and pyroxene can be considered the main mineral phases of these rocks. The rocks are enriched in LIL and LREE elements and depleted in HFS elements. The ratios of trace elements and rare earth elements in the studied region indicate that the basalts were formed by melting a garnet bearing peridotite at great depths and pressures. Negative Ce anomaly, Nb negative anomaly, Pb positive anomaly the role of continental lithosphere in contaminating the magmatic sources of volcanic rock in the study area. The Pb/Ce ratio similar to ocean island basalt (OIB) sources, induces OIB sources, the asthenospheric mantle, in the initial formation of basaltic magma. it can be concluded that the volcanic rocks of the area have formed in an intra-plate environment in an extensional regime.

The Gooreh Mountain is located about 55 km northwest of Anarak (northeast of Isfahan) and in the western margin of the Central-East Iranian microcontinent (west of the Yazd block). The field studies show that the Eocene volcanic rocks in this area present two lithologies of gray-colored dacite and light-colored rhyolite. Dacite lavas cross-cut the rhyolite ones and are younger. Petrography indicates that dacites contain the major minerals of plagioclase (labradorite and bytownite), clinopyroxene (augite) and quartz, and rhyolites are mainly composed of plagioclase, sanidine and quartz. Chlorite, calcite, hematite and limonite are the secondary minerals in both rock units, formed by the alteration of clinopyroxene, plagioclase and magnetite. The main textures of these rocks are porphyritic, glomeroporphyritic, anti-rapakivi, sieved and poikilitic. The crystallization order of minerals in dacites is magnetite, clinopyroxene, plagioclase and quartz, and in rhyolites, is plagioclase, sanidine and quartz. Whole rock geochemical analyses show that the studied volcanic rocks of the Gooreh Mountain are sub-alkaline (calc-alkaline magma series) in nature. Moreover, the chondrite and primitive mantle-normalized diagrams are characterized by the enrichment of LREEs and LILEs and depletion of HFS elements (e.g., Ti, Nb and Ta). The negative TNT (Ti, Nb and Ta) anomalies probably indicate subduction-related volcanic arc magmatism. The dehydration of subducting slab and partial melting of the mantle wedge spinel peridotites produced a basic magma that, during ascent through the lower and middle continental crust, led to melting of amphibolites and formation of acidic magmas.

Subduction-related magmas are characterized by enrichment of large ion lithophile elements (LILEs), light rare earth elements (LREEs) and depletion in high field strength elements (HFSEs) (Harangi et al., 2007). These geochemical signatures of magmatic rocks are commonly explained by the addition of hydrous fluids from subducting oceanic lithosphere combined with the flux of melts from subducted sediments to the mantle wedge, lowering the mantle solidus and leading to magma generation (Aydınçakır, 2016). Asthenospheric mantle, subcontinental lithospheric mantle and/or lower crust may be the principal source of these rocks (Eyuboglu et al., 2018). In addition, magma differentiation processes, such as fractional crystallization, crustal contamination, and magma mixing may also play an important role in the genesis of these rocks.This research study presents new petrological and geochemical data from the volcanic rocks with NW–SE trending, which are situated in the northwestern margin of the Central –East Iranian Microcontinent (CEIM) (south-east of Khur, Isfahan Province) which have been formed during the peak activity of Eocene. Study of this typical small volume subduction- related magmatism will be useful in understanding the origin and geological evolution of the Central Iran in Cenozoic.

The petrographic investigations on Eocene volcanic rocks from the SE of Khur area were carried out with an optical microscope (Olympus-BH2) in the petrology Laboratory of the University of Isfahan, Iran. Major and trace element concentrations of samples from whole- rocks were obtained by a combination of inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) at the Als Chemex Laboratory of Ireland. The chemical compositions of 4 samples (B865, B866, B867, and B868) were determined by Neutron Activation Analysis (NAA) in the Isfahan Activation Center. The detection limit was 0.01% for all major element oxides and 0.01 ppm for rare earth elements. Mineral abbreviations were adopted from Whitney and Evans (2010).

Eocene volcanic rocks with trachy-basalt and trachy-basaltic andesite composition are exposed in the northwestern part of the Central-East Iranian Microcontinent (CEIM) (SE of Khur, Isfahan Province, Central Iran). These rocks which have a dominant northwest-southeast trend crosscut the Cretaceous sedimentary rocks.Petrography and mineral chemistry analyses indicate that the predominant rock-forming minerals of volcanic rocks are olivine, plagioclase, clinopyroxene and orthopyroxene. Phenocrysts set in a fine to medium grained matrix of the same minerals plus sanidine with minor amounts of opaque minerals. Secondary minerals are chlorite and calcite. The most common textures of these rocks are porphyritic, microlitic porphyritic, poikiolitic and glomeroporphyritic. Geochemical analyses of whole rock samples show that these rocks have been enriched in alkalies and large ion lithophile elements (Cs, K, Rb, Sr, Ba,), and have been depleted in high field strength elements (HFSE) (Ta, Nb, Ti). All samples indicate moderate to high fractionation in LREE patterns. These geochemical signatures point out to the subduction-related calc-alkaline nature of these rocks and their similarity to volcanic rocks of continental arcs or convergent margins (Yu et al., 2017). Pb enrichment and low values of Nb/La, Nb/U and Ce/Pb ratios reveal that crustal contamination has played an important role in magma evolution (Srivastava and Singh, 2004; Furman, 2007). The large volume of hydrous fluids coming from the subducted slab rather than sediments have caused enrichment and metasomatism of the subcontinental lithospheric mantle source. The geochemical characteristics of the studied rocks suggest that the parental magma have been derived from partial melting of a metasomatized spinel lherzolite of lithospheric mantle, which was previously modified by dehydration of a subducting slab. The tectonic environment, in which these rocks were formed has probably been a volcanic arc. Subduction of oceanic crust around the Central-East Iranian Microcontinent (CEIM) is the most reasonable mechanism which can be used to explain enrichment in volatiles of the mantle, and the calc-alkaline magmatism of the study area in Eocene times.

The Zangalou mine area, a part of NW Bardaskan magmatic assemblage, located south of Sabzevar and northwest of Bardaskan cities in Khorasan Razavi province. The rock units of the area are dominated by sedimentary and volcanic racks (andesite, trachyandesite, latite and andesitic tuff). The dominant minerals are plagioclase, hornblende, pyroxene and alkali feldspar locally affected by argillic and propylitic alterations and the main textures are porphyritic, glomeroporphyritic, amygdaloidal and fine grain. The rocks under study formed in continental volcanic arc related to subduction zone, are calcalkaline in nature, metaluminous in composition and classified as shoshoite series. LREE and LILE enrichment compared to HREE and HFSE of the investigated rocks indicate their magma generation in subduction setting. Both Zr/Ba and Sm/Yb ratios point to lithospheric mantle origin and the rare or the absence of garnet in the origin respectively. The parent magma formed from partial melting of an enriched phlogopite spinel lherzolite. The geochemical properties of Zangalou share many signatures with those of the volacic rocks distributed in other parts of NW Bardaskan volcanic assemblage indicate high similarity in geochemical signatures of volcanic rocks. Studying geochemistry of volcanic rocks in these areas indicates formation of these rocks in a subduction setting.

Around The Karik village, east of Meiduk mine, Eocene volcanic rocks (andesitic basalt, andesite, dacite and rhyolite) and pyroclastic rocks (agglomerate and tuff) are exposed. These rocks are cut by several andesitic dikes. The major textures in the volcanic rocks are porphyritic and flow textures. The minerals such as plagioclase, alkali feldspar, quartz, pyroxene, amphibole, biotite and opaque are present as phenocrysts and fine grains. Sometimes, feldspar crystals (mainly plagioclase) are found as oriented microlites. In some cases, within the plagioclase phynocrysts disequilibrium textures such as sieve texture, corrosion and zoning are observed. Quartz crystals are corroded. Amphibole and biotite crystals are changed into Fe-Ti oxides on their rims. These textures are probably attributed to magma mixing, water vapor changes and decompression due to rapid ascent of magma. The Karik volcanic rocks are calc-alkaline and mainly metaluminous in nature. Primary mantle and chondrite normalized multielement diagrams for the study rocks are spiked and they have several peaks and troughs. In the diagrams, the depletion of the high field strength elements such as Nb, Ta, Ti and P is obvious which is characteristic of the subduction magmatism. The sharp positive anomaly of Pb might be attributed to crustal contamination. The chondrite normalized RRE pattern of the study rocks is relatively smooth with enrichment of LREEs relative to HREEs that is due to the high abundance of LREEs in the source or crustal contamination. According to the petrological and geochemical evidence, the Karik volcanic rocks are formed in an active continental margin setting due to the subduction of Neothetys oceanic lithosphere beneath the Central Iran micro–continent.

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.

The study area in north of Iran is located between 49 °, 30' and 50 °, 00' longitudes and 36 °, 30' to 37 °, 00' latitudes and in the 1.100000 sheet of Jirandeh. This area is considered as part of the structural zone of Iran in Alborz zone and is part of Tertiary zone. In this paper, with the help of geochemical evidence in Rudbar region, as part of Paleogene magmatism in Alborz, an attempt has been made to comment on the tectonic petrogenetic of the region.

After field studies, considering lithological varieties of the volcanic units in the region, 100 samples were collected and thin sections were prepared and studied in terms of petrography using polarizing microscope. Then, among the mentioned samples, 22 samples with the lowest weathering and most lithological variety were selected to analyze the major elements using XRF method and the trace and REE elements by ICP-MS method at SGS laboratory in Toronto. In order to analyze data, the software Igpet 2007 and GCDkit are used.

The studied area is located in the sheet of Jirande at a scale of 1:100000 ,that are outcrops of volcanic and pyroclastic rocks of Paleogene age. Based on petrographic studies carried out on the lavas’ units, three rock units were distinguished: a) olivine basalts, b) andesitic basaltic and basaltic andesite, c) hornblende pyroxene andesites and andesites. In most investigated rocks, there are different types of xenoliths and xenocrysts. Xenoliths are composed of gabbro, diorite and sometimes basalt. These xenoliths and xenocrysts are petrographic evidence for magmatic contamination.   The positive correlation of Na2O and K2O and the negative correlation of Fe2O3, MgO, CaO oxides with the increasing of SiO2 evidence, indicates fractional crystallization in the magma evolution trend of rocks in the area. The constant trends are also maintained through series, which were exposed to the AFC process and assimilation with fractional crystallization.
Comparing the pattern process of incompatible rare elements to crust values in mafic and intermediate terms indicates crustal contamination of mafic rocks to the lower crust and contamination of intermediate rocks towards upper crust. Linear correlation between the ratio of Y/Nb compared to Zr/Nb indicates the origination of magmas from MORB source mantle which were somewhat contaminated with the continental crust rocks.

Geochemical studies represent original relationship between all the studied rocks. This relationship indicates the crystal fractionation in the magma that forms these rocks. Investigations of the ratios of incompatible trace elements, suggest that the mafic samples of the region are close to MORB asthenosphereic mantle source. Also, the trends between primary and evolved samples indicate a linear arrangement between the MORB source mantle and the continental crust, representing an interaction of the MORB mantle-derived magmas with continental crust. All geochemical evidence indicates that the volcanic rocks in the area were originated from melting of a MORB asthenosphere mantle source with spinel facies, which was contaminated with the continental crust rocks to some degree.
The crustal contamination of these basalts has caused, firstly, these rocks to follow exactly the elemental processes of the crust, and secondly misleadingly show the geochemical characteristics of rocks in subduction zones. This means generating magmas from mantle MORB source with crustal contamination are commonly seen in within-plate continental rift magmatisms.

The studied volcanic-sedimentary sequence located at the East-Azarbaijan province, north Marand and in the Central Iranian structural zone. The studied sequence composed of alternative sandstone, shale, conglomerate, limestone, felsic volcaniclastics, alkalibasalt and rhyolite which outcropped below the Permian sedimentary sequence and on the Devonian sedimentary rocks. Magmatism in the area has a bimodal magmatic characteristic and the basaltic rocks have alkaline affinity. They are characterized by enrichment of LILE over HFSE and show significant OIB-type trace element signatures. On the basis of trace element data, the basic rocks generated by low degree partial melting of garnet-spinel lherzolite mantle source with ocean island basalt characteristics, which fractionated en route to the surface. On the basis of geological and major and trace elements data, the felsic rocks are comparable to A-type granitoids and their trace element ratios are very close to determinate bulk continental crust composition which indicate their crustal origin. The felsic rocks were originated by the dehydration melting of a tonalite or granodiorite source with a plagioclase rich residual assemblage. The Carboniferous bimodal volcanism were induced by continental rifting and asthenospheric upwelling during early phases of Neotethys opening.

The Hormuz and the Gachin salt domes are located in the south of Bandar Abbas, the Hormozgan Province, in Zagros Structure Zone. The domes are dominated by andesite, trachy-andesite, basalt, dacite, and rhyolite belonging to Permian to Triassic age. Based on geochemical evidence, these rocks are calc-alkaline originated in orogenic setting related to subduction environment. The presence of oxide minerals (hematite and magnetite) in the volcanic rocks of the domes reflect oxidization conditions and high oxygen activity during their formation. Negative TNT and high LREE/HREE anomalies along with positive Pb anomalies and low Nb/U ratios (0.48 to 14.6), as well as tectonomagmatic diagrams indicate that the studied rocks are magmatic products of primary mantle origin, which has been metasomatized by continental crustal rocks. High Ba/Nb values, low Sr and Zr/Y>3 ratio along with geochemical diagrams, confirm the characteristics of arc magmas related to the formation of the rocks under study in a subduction environment.

The south Natanz volcanic zone located in the central part of Urumieh-Dokhtar magmatic arc and the north of Isfahan. The area is dominated by the Eocene volcanic rocks ranging from acidic to intermediate and relatively basic affinity. Petrologically, they consist of rhyolite, dacite, andesite, basaltic trachyandesite and basaltic andesite. Mineralogically speaking, except for the acidic rocks, the other rocks are mainly made of plagioclase and clinopyroxene up. According to EPMA, the composition of clinopyroxene and plagioclase is augite and andesine to bytownite. Having features such as zoning and sieve texture in phenocrysts of plagioclase, roundness, and corrosion gulf in minerals belonging to the volcanic rocks reflecting the existence of unequilibrium during magma solidification. Considering geochemical features of these rocks, we can realize that they are calc-alkaline with potassium from intermediate to high LILE enrichment, and negative Nb-Ti anomalies. On the spider diagram, primitive mantle- normalized with Pb-enrichment can be seen which may be attributed to crustal assimilation. The negative anomalies of Nb and Ti on the spider diagram reflect subduction process, the crustal involvement in magmatism processes, or an indication of deficiency of these elements at the origin, the stability of Nb-Ti bearing phases during partial melting or separating these elements in the course of fractional crystallization process. The chondrite- normalized REE pattern points to LREE enrichment in comparison with HREE. The volcanic rocks studied have been originated in a magmatic arc.

A completely lithologic sequence of Permian strata including Doroud (mainly of sandstone and shale), Ruteh (mainly of limestone with interbed marl) and Nesen (mainly of limestone and shale) formations is exist in Central Alborz zone from Siyah-Bishe and Harijan in Chalous Road to Yoush, Baladeh, Zarin-Kamar and Varazan in south of Amol in Mazandaran Provence. Based on the field geology and petrography, these igneous rocks with basic alkaline nature are found as dike, sill and small diabasic, micro-gabbroic and lamprophyric intrusions in the Doroud Formation and as basaltic lava flows and related pyroclastics in the upper part of Ruteh Formation. In fact, low-depth microgabbroic and lamprophyric intrusions in the Doroud Formation were residual and solidified melt in feeding vents of the basaltic volcanism in the upper part of Ruteh Formation. Doroud Formation was deposited in a Fluvial- Deltaic environment in Early Permian, Ruteh and Nesen formations were deposited in carbonate platform (lagoon, barrier and open marine) in Middle–Late Permian respectively. Lack of continues reefal facies and turbiditic sediments indicate that the Routeh and Nesen carbonate formations deposited in a carbonate ramp platform. At this time, the central Alborz was as a passive margin in the south side of the Paleo-Tethys and its alkaline basic magmatic activity is interpretable with the Late Paleozoic extensional tectonics in the north side of the Gondwana and simultaneously with initial stages of Neo-Ttethys development in Zagros. According to Berberian and King (1981), Paleozoic magmatic activity has not been extended in Iran, but the study of these rocks is a very important key to better understanding the geological events of this period in Iran and adjacent countries. For example, the opening time of the Paleo-tethys and Neo-tethys oceans need to understand their geologic events (such as magmatism and metamorphism) in the Paleozoic era. One of the most widespread events is the magmatic activity of the Ordovician–Silurian in the Eastern Alborz (Sultan Meydan Complex), which can be certified on the occurrence of extensional tectonics in the early stages of opening of the Paleo-Tethys ocean (Ghasemi and Khanalizadeh 2012; Ghasemi and Kazemi 2013; Derakhshi and Ghasemi 2013, 2014; Derakhshi et al. 2014, 2015; 2017). Then, other magmatic phases have been occurred in the Devonian (Ghasemi and Dayhimi 2015; Dayhimi 2012; Derakhshi and Ghasemi 2013, 2014), Carboniferous (Naderi et al. 2018a,b) and especially in Permian (Berberian and King 1981; Vahdati Daneshmand 1991,1999; Saidi and Ghasemi 1991; Gaetani et al. 2009; Delavari et al. 2017; Rostami et al. 2018). The discussions and views on the place of Iran during Permian and the closure time of the Paleo-Tethys ocean and opening of the Neo-Tethys ocean reveal the importance of the Permian magmatism. After Permian, with developing of the Neo-Tethys ocean, some parts of Iran (such as Central Iran and Alborz), as the Cimerian territories, were separated from the north of Gondwana and moved to the northern Eurasia super-continent (Gaetani et al. 2009). With the closure of the Paleo-Tethys ocean at the Early Jurassic (Boulin 1988) or the Late Triassic (Stöcklin 1974; Alavi et al. 1997; Stampfli and Borel 2002; Horton et al. 2008; Wilmsen et al. 2009; Zanchi et al. 2009), which is characterized by the Eocimerian discontinuity in Alborz, the connection of the cimerian microcontinent to southern Eurasia have been occurred. Thus, over the Middle to the Late Permian, the cimerian territories embedded between the two oceanic zones, the newly emerging Neo-Tethys in the south (Zagros) and the destroying Paleo-Tethys in the north becoming closer to Eurasia (Stampfli et al. 2002; Nikishin et al. 2002; Gaetani et al. 2009; Berra and Angiolini. 2014; Domeier and Torsvik 2014). The Permian–Triassic extentional phase is one of the most important rifting phases in Iran, indicating the opening of the Neo-Ttethys oceanic basin whose signs are found as basaltic magmatism in Alborz and other parts of Iran (such as Central Iran and Sanandaj–Sirjan) (Berberian and King 1981; Ghaesmi and Jamshidi 2012; 2013; Ghasemi et al. 2018). The studied area is located in northeastern Baladeh (Central Alborz) from Siyah-Bishe and Harijan on Chalous road to Yoush, Baldeh, Zarrin Kamar and Varazan in south of Amol in Mazandaran province. It contains sedimentary units of Permian (Doroud, Ruteh and Nessen formations), along with igneous basic alkaline rocks (volcanic and intrusive). Main spreading of volcanic rocks in the Baladeh area has been reported between the Ruteh and Nessen formations (Vahdati Daneshmand 1991,1999; Saidi and Ghasemi 1991; Delavari et al. 2017; Rostami et al. 2018), but based on the findings of this research and in according to Gaetani et al. (2009), these magmatic rocks are located not between the Ruteh and Nesen Formations, but in the form of intrusive bodies in the Doroud and the lower part of the Ruteh formations, and in the form of extrusive and pyroclastic rocks in the upper part of the Ruteh Formation. The intrusive bodies that were originally solidified magma in the feeding vents of volcanic rocks widely cropped out in the form of dikes, sills and small diabasic, microgabbroic and lamprophyric intrusions in the Doroud Formation and in the lower part of the Ruteh Formation in Siyah-Bishe and Harijan on the Chalous road and are not mentioned in any previous studies. In addition, lamprophyric dikes are also reported in the region for the first time in this study.  The systematic study of the Paleozoic igneous events of the Alborz region (Ghasemi and Khanalizadeh 2012; Ghasemi and Kazemi 2013; Derakhshi and Ghasemi 2013; 2014; Derakhshi et al. 2014, 2015; 2017; Dayhimi 2012; Naderi et al. 2018a; b) and northeastern Iran around Mashhad (Li et al. 2018; Mobasheri et al. in press) and their use to study the evolution of the Paleo-Tethys ocean needs to studying and precision field surveying, petrography, mineral chemistry, as well as precise chemical analysis of major, minor, trace and rare earth elements of whole rocks, and even isotopic analysis and age dating from the Permian igneous specimens of Central Alborz. But, due to the variety of topics, the large amount of the data and processing and interpretation, this paper only refers to the precise stratigraphic position, diversity occurrences of igneous rocks, geological relations and their geomodynamic significance in the analysis of the evolutionary trend of the Alborz Basin during the Permian period. Studies and field sampling were carried out in all Permian outcrops of the region, using previous research data and tracking these rocks in high-resolution satellite images of the area, as well as performing via precise cross-sectional surveys in the available outcrops in a systematic and selective manner. Preparation of thin sections and their petrographic studies have been carried out in the laboratories of the Faculty of Earth Sciences, Shahrood University of Technology.  A completely lithologic sequence of Permian strata including Doroud (mainly of sandstone and shale), Ruteh (mainly of limestone with interbed marl) and Nesen (mainly of limestone and shale) formations is exist in Central Alborz zone from Siyah-Bishe and Harijan in Chalous Road to Yoush, Baladeh, Zarin-Kamar and Varazan in south of Amol in Mazandaran Provence. Based on the field geology and petrography, these igneous rocks with basic alkaline nature are found as dike, sill and small diabasic, micro-gabbroic and lamprophyric intrusions in the Doroud Formation and as basaltic lava flows and related pyroclastics in the upper part of Ruteh Formation. The intrusive rocks show ophitic, subophitic, poikilitic, poikilophitic, microlitic porphyry, intergranular and microgranular textures composed of olivine, clinopyroxene, plagioclase and amphiboles as the main minerals. The extrusive rocks show amygdaloidal, hyalomicrolitic porphyry, microlitic porphyry, hyaloporphyry, intersertal and trachytic textures composed of olivine, clinopyroxene and plagioclase as the main minerals. The amigdals filled by secondary minerals such as calcite, chlorite and quartz. Compositional zoning and sieve texture in clinopyroxene and plagioclase and skeletal texture and corrosion of crystal margins in olivine and clinopyroxene are widely seen. In fact, low-depth microgabbroic and lamprophyric intrusions in the Doroud and the lower part of the Ruteh formations were residual and solidified melt in feeding vents of the basaltic volcanism in the upper part of Ruteh Formation. According to Delavari et al. (2017) and Rostami et al. (2018) Permian magmatic rocks of the Baladeh area have sodic alkaline nature and are derived from crystallization of a basaltic melt originated from partial melting of an Oceanic Island Basalt (OIB) source in a within plate tectonic setting (a deep garnet bearing mantle source of HIMU type). This tectonic setting can be the result of the extensional tectonics prevailing of the Middle–Late Permian, which is accompanied by pressure reduction on the mantle, rising the deep mantle plume, melting it at high depths, and formation of the basaltic magma. This extensional regime coincided with the early stages of crust uplifting and formation of the rift basins as a prelude to the formation and evolution of the Neo-Tethys Ocean in the southern part of the Paleo-Tethys. The geodynamic rearrangement of the Tethys realm during the Late Paleozoic–Early Mesozoic, has been accompanied by magmatic activity along the northern margin of Gondwana from the east of the Himalaya to Tibet, Oman, Iran and Turkey (Zhu et al. 2010). From the petrographic data and the chemical analysis of igneous rocks, along with the evidence of stratigraphy, facies and sedimentary environments can be used to determine the tectonomagmatic setting and the paleogeography of the Alborz land during Permian. Accordingly, Doroud Formation was deposited in a Fluvial-Deltaic environment in Early Permian, Ruteh and Nesen formations were deposited in a carbonate platform (lagoon, barrier and open marine) in Middle–Late Permian respectively. Lack of continues reefal facies and turbiditic sediments indicate that the Routeh and Nesen carbonate formations deposited in a carbonate ramp platform. At this time, the central Alborz was as a passive margin in the south side of the Paleo-Tethys and its alkaline basic magmatic activity is interpretable with the Late Paleozoic extensional tectonics in the north side of the Gondwana and simultaneously with initial stages of Neo-Tethys development in Zagros.

Eocene volcanic and volcano- sedimentary rocks cover a large area in the Gardaneh Ahovan northeast of Semnan. These rocks comprise mainly of basalt, andesite, trachyandesite, rhyolite and dacite with hyalo porphyry, porphyry and glomeroporphyry textures. The basaltic rocks are composed of plagioclase and clinopyroxene phenocrysts. Sericite, kaolinite, calcite and chlorite also form the secondary minerals in these rocks. The size of the clinopyroxenes of these rocks range from fine to medium and their compositions include iron-magnesium-calcium type and plot in the diopside field. Medium-size clinopyroxenes show reverse zoning and compositional changes so the middle zone (btween core and rim) is depleted in Fe, Al and Ti whereas enriched in the Mg, Ca and Si. The determination diagrams of the magmatic series and tectonic environments, based on the chemical composition of clinopyroxenes, suggest that they are crystallized from alkaline to sub-alkaline magma, contianing 2-5% water and high oxygen fugacity. Thermo-barometery calculations also show that these clinopyroxenes were crystallized in pressures of ~1 kbar and temperatures of 1110-1230 °C.

The study area is located in the Isfahan province and at the north of East Alloun Abad village. This area is a part of Urmia - Dokhtar belt in Central Iran. A large part of the area is formed from Eocene igneous rocks. These rocks include basaltic andesite and pyroclastic rocks of ignimbrite and tuff. These rocks show porphyritic and microlithic texture with plagioclase, amphibole and clinopyroxene as the main mineral constituents. The secondary minerals such as chlorite, calcite, epidote and iron oxide are formed due to alterations. Electron microprobe analyses reveals that clinopyroxenes are diopside - augite. The study of clinopyroxene chemistry showed that the water was between 2 to 10% during clinopyroxene crystallization. The parental magma was calc-alkaline and tectonic setting is a subduction-related environment, based on clinopyroxene composition. Geothermobarometry of clinopyroxene gives temperature range of 925-1091°C and pressures range of 2-10 kbars for the formation of clinopyroxene in these rocks.

The study area is located the south of Gazik (east of Birjand) and along the eastern margin of the Sistan suture zone. The south of Gazic volcanics crop out as a north- south trending unit. They are predominantly intermediate extrusives including andesite and basaltic- andesite. Based on field relationships and the age of adjacent sedimentary rocks, the volcanics are late- Cretaceous (Maastrichtian) in age. Petrographically, plagioclase is the predominant phase and clinopyroxene appears as the main ferromagnesian mineral. The chondrite- normalized rare earth element (REE) patterns are characterized by moderate light REE (LREE) enrichment relative to heavy REE (HREE) and the ratio of (La/Yb)N in the ranges of 2.71 to 8.68. Furthermore, the chemical characteristics of the volcanics including enrichment of large ion lithophile elements (LILE) like K, Rb and Ba and depletion of high field strength elements (HFSE) like Nb, Ta and Ti are similar to subduction zone magmatism. Based on trace element concentrations, it seems that the melts were derived from a mantle wedge intensely modified by subduction zone fluids. Considering minor and trace element contents, the studied rocks are more similar to island arc volcanics. Therefore, the Sistan Ocean has probably recorded an active subduction zone in the late Cretaceous, which is in conflict with the pre- late Cretaceous Lut and Afghan continental collision.

The studied volcanic rocks are located in 35 km North West of Tabriz and consists of dacite, andesite, basalt and basaltic andesite. Based on structural geology evidences, this area is part of west Alborz – Azerbaijan zone. Plio - Quaternary volcanism is started with explosive eruptions of acidic and intermediate materials and in last and young stage basaltic lava erupted from faults and fractures that are visible with layered structure. Prismatic basaltic lavas covered pyroclastic rocks and andesitic lavas. The main constituent minerals in these rocks are olivine, plagioclase, amphibole and pyroxene. In the diagram to determine the magmatic series, samples belong to two magmatic series calc-alkaline and alkaline and show characteristics of bimodal magmatism. Studied volcanic sequence show a reverse volcanic series that it is results of characteristics of bimodal volcanism. In spider diagrams which normalized with chonderite and primitive mantle amounts, these rocks show enrichment of HREE and HFSE elements and depletion of LREE and LILE like Ti, Nb and Ta (TNT). According to the trace elements diagrams La to La / Sm and La / Yb to Yb ratio, magma genesis can be formed from a low rate of partial melting of garnet lherzolite mantle and with ascending and emplacement of magma in the upper level of the crust partial melting of crustal rocks produced acidic and intermediate volcanic materials. Tectonomagmatic diagrams show that these rocks formed in post collision volcanic arcs.