نشریه پترولوژی
پیاپی 53 (بهار 1402)

The Qorveh batholith, in the N-Sanandaj-Sirjan Zone, comprises several gabbroic, dioritic and granitic masses intruded the Jurassic metamorphic assemblage (i.e., schist, amphibolite and marble). In spite of a number of studies which have been carried out on the various aspects of these rocks, but none of them has been studied the Mixing/Mingling model. Thus, the purpose of present study is to examine the development of the magmatic mixing process in the rocks under study based on geochemical data obtained from the enclaves and their host rocks as well as their field relationship.

In order to study the geochemical properties of intrusive rocks, 10 samples of enclaves and their host rocks. The rock composition with the least amount of alteration was selected and sent to the Pennsylvania State University of (USA) to determine the amounts of major elements by ICP-AES method, and rare and rare earth elements by ICP-MS method.

Field observations:

The enclaves, in the intrusive masses under study, are finer than that of their host rock. Therefore, they belong to the group of mafic fine-grained enclaves or microgranular mafic enclaves. (MMEs). The (MMEs) are in rounded and elliptical shapes in the host rocks and generally they have a sharp contact with their host and are composed of igneous minerals.

Petrography:

The host rocks include granite, granodiorite and monzonite, and the enclaves are dioritic and gabbroic in composition. There are similar minerals in the enclaves and their host rocks, but they often differ in the amount of minerals. They are mainly composed of mafic mineral and plagioclase. While their host rocks are characterized by smaller amounts of these minerals, the host rocks instead have higher amounts of quartz alkali feldspar. The transfer of plagioclase crystals at the common boundary of the enclave and the host rock is evidence of the magmatic mixing process in the nature of the intrusive masses studied. A number of enclaves contain megacrystals of feldspar potassium and quartz taken from the host rocks. This supports the formation of enclaves by mixing.

Geochemistry:

Geochemical studies indicate that these rocks are metaluminous, belonging to calc-alkaline magma series, having I-type characteristics. In Harker diagrams, mafic enclaves have higher MgO, TiO2, P2O5, Na2O, FeO(t), Al2O3, MnO and CaO contents than that of the host rocks, and lower K2O and SiO2 contents. The higher contents of CaO, MgO and FeO(t) in the enclaves, compared to their host, confirms their more mafic nature, which is usually proportional to the higher contents of mafic minerals in the modal of the enclaves than that of the host. The enrichment of the studied enclaves in Co, Cr, Ni display that these rocks are globules of mafic magmas mingling to felsic type.

According to field observations as well as petrographic studies, the effective factor in the evolution of magma forming intrusive masses has been mentioned as magmatic mixing. The presence of mafic fine-grained enclaves with evidence of disequilibrium textures such as feldspar with poikilitic texture, the presence of mafic masses and needle apatite, small blades-shaped plagioclase within large plagioclase or two types of plagioclases, and zoning all confirm magmatic mingling/ mixing processes. Considering that the magnesium number (Mg#) in the mantle is about 0.7 and the studied enclaves with a high magnesium number of 0.52-0.62 are evidence of the involvement of mantle-derived mafic magma. High values of Mg# in enclaves compared to their host rock (0.34-0.48) shows the mixing of magmas from the mantle with the crustal magmas. Magma mixing model has also been considered by geochemical differentiation diagrams. The trend of the samples is a curve and indicates that the effective process in magma evolution is most likely magmatic fusion. Numerous studies have shown that mafic microgranular enclaves are globules of a mantle derived mafic magma that crystallize rapidly in the injected felsic magma from the crust and, as a result, become more viscous, forming separated magmatic bubbles. In addition to the mentioned geochemical features, the enclaves are poor in LREE and LILE and enriched in Ti compared to the host rocks. Therefore, they seem to have originated from two different magmas and are placed together due to magmatic mixing.

The host rock units in the studied intrusions include granite, granodiorite, monzonite and gabbroic, dioritic enclaves. The constituent magma of this complex is in I- type, metaluminous and is in the calc-alkaline series. Based on the studies, the dominant process in the evolution of magmatic mixing. Some new findings include the presence of reversals in submerged slabs and the penetration of fleshy compounds. Which naturally have different temperatures and compositions compared to higher crustal horizon magmas, provides conditions for the occurrence and the development of the magmatic mixing process.

Many lamprophyric dykes' outcrops are found in Azerbaijan (in the northwest of Iran). These dykes which were the subject of many studies are including camptonite dykes in Misho Mountain, kersantite dykes of Goye-Poshti Mountain of Maragheh, camptonite and sannaite dykes in Horand, minette dykes of Varzeghan, minette dykes of Marand, minette dykes of Khoy, and minette dykes of Saray volcano. For the first time, Amel (1994) reported the occurrence of lamprophyre in the Monavvar region. According to him, this lamprophyre is spessartite and has Calc-alkaline affinities. In this study, we performed a detailed petrographic study of this lamprophyre. Besides, by using clinopyroxene mineral chemistry and whole rock chemistry, we try to investigate the petrogenesis of these lamprophyres from different aspects.

General geology:

Monavvar region is located in the east Azerbaijan province of Iran. Monavvar region is a part of the Alborz-Azarbaijan zone. Field observations show two spessartite dykes intruded in the andesitic lavas of the studied region. The age of andesitic lava and spessartite dykes is Plio-Quaternary because the andesitic lava intruded in Pliocene pyroclastic lava. Spessartite has a blackish-brown color in the hand specimens.

Petrography:

The main petrographic texture of these lamprophyres is the Porphyry texture. The major minerals are plagioclase microliths (10-15 volume %), orthoclase (5-10 volume %), hornblende phenocrysts with burnt rim (40-50 volume %), clinopyroxene (>20 volume %), and biotite (10-15 volume %). The accessory minerals include zircon, sphene, and apatite. The plagioclase has higher content than orthoclase and both of these minerals could be seen only as microlith. Regarding the nomenclature scheme of Le Maître (2002), these features indicate that these lamprophyres are spessartite.

Mineral Chemistry:

The mineral chemistry of amphibole shows a magnesio-hastingsite composition. However, biotite is phlogopite-eastonite and feldspars are orthoclase and oligoclase in composition.

Mineral chemistry of clinopyroxene studies The clinopyroxenes are in the field of Quad in the Q-J diagram and diopside in the En-Fs-Wo diagram. According to the AlVI+2Ti+Cr-AlIV+Na diagram for clinopyroxenes, Monavvar spessartite has occurred in almost the stable and low oxygen fugacity status.  Based on Soesoo (1997), the clinopyroxenes were crystalized under 1100-1200 ℃ and 2-6 kbar. The chemical composition of clinopyroxenes indicates subduction-related volcanic arcs and within-plate tholeiitic environments.

Whole rock geochemistry of Monavvar spessartite:

Most lamprophyre samples are plotted in the trachybasalt field on the total alkali (K2O+Na2O) versus silica (Si2O) classification diagram. They show alkali basalt composition on the Zr/Ti2O-Nb/Y plot.  K2O-Si2O diagram classified them as calc-alkaline lamprophyres.

REE Geochemistry:

In the spider diagram of studied samples, Nb and Ti show a distinctive negative anomaly, and U, La, K, Th, and Ba show a positive anomaly. HFSEs depletion and LILEs enrichment of samples are characteristics of shoshonitic and calc-alkaline magma. Negative Nb and Ti anomalies could be a result of Ti-bearing mineral segregation or high oxygen fugacity. LILEs enrichment could indicate that aqueous fluid is present during magma-forming processes or crustal contamination during magma evolution. Y depletion could happen as a result of amphibole segregation.   All samples show highly fractionated steep REE patterns which means a distinctive enrichment of LREEs relative to HREEs. LREEs enrichment occurs as a result of small degrees of magma partial melting. However, this feature is a character of shoshonitic and calc-alkaline magma. The REE pattern of Monavvar spessartite does not show an Eu anomaly. In the basic rocks, concurrent crystallization of amphibole and plagioclase caused a lack of Eu anomaly.

Tectonic setting of Monavvar Spessartites;

Based on the Zr-Y diagram and Nb-Zr-Ce/P2O5 diagram, Monavvar spessartites are ascribed to an arc-related tectonic setting.

Petrogenesis of Monavvar Spessartites:

Based on the whole rock composition of Monavvar spessartite, Ni=68-92 ppm, Co=1-23 ppm, Cr=59-125 ppm, and Mg#=25-32%. These values mean the lamprophyres could not be considered as the primary magma, but probably they are very close to the primary magma composition. On the other hand, on Dy/Yb-La/Yb diagram, the samples are scattered in the field of garnet-bearing mantle zone. Similarly, the La/Yb-La diagram indicates the garnet presence in the source peridotite, in addition to the 5-15 % of mantle peridotite partial melting for producing Monavvar spessartite melt.

Geodynamics of Monavvar region:

According to Rock (1991), petrographical, mineralogical, and geochemical investigations revealed M6 and M7 magmas for the Monavvar spessartites. M6 was produced by contamination of primary magma by mantle elements and M7 was produced by crustal contamination of primary magma. By considering this, the function of strike-slip dextral faults in Azerbaijan (northwest of Iran) could be responsible for Monavvar spessartites formation. Due to the mentioned faults function, transcurrent basins are made across the faults. Transcurrent basins caused low partial melting degrees of the metasomatized lithospheric mantle and produced alkaline basic magma. Contamination of this magma in different depths could form spessartite magma.

Volcanic rocks with adakitic nature, are outcropped, in the south of Rudbar city as a part of the Alborz magmatic zone and the northern part of the Alborz zone. Most of the rock units in this area are volcanic and pyroclastic belonging to the Tertiary age and specifically Middle Eocene. For this study, we present new data to understand the origin and tectonic setting of the adakitic early Cenozoic magmatism in the southern part of the western Alborz orogenic belt.

Regional Geology:

Based on the 1:100,000 Guilan geological map (Nazari and Salamati, 1998), the predominant geological units of the region include the Paleozoic, Mesozoic, and Cenozoic stratigraphic units. The volcanic activity resulting from the subduction of an oceanic crust beneath the active continental margin of Alborz began in Paleocene and its peak is attributed to the Lutsin period (Nazari and Salamati, 1998).

Following microscopic studies, 11 samples were analyzed at Actlabs Lab in Canada by ICP-MS method. IGPET and GCDKIT software were applied to draw diagrams and interpret the data. Petrography and Whole rocks chemistry The studied lavas consist mainly of dacite to trachy-dacite, rhyodacite, and rarely rhyolite. Abundant plagioclase as phenocrysts and microlites and rare amphibole, biotite, and quartz with hyaloporphyritic, microlithic porphyry to felsitic porphyry and microfelsitic textures are the dominant petrographic features of these rocks. Geochemically, they are characterized by mean value of 61.87 wt%< SiO2<66.54, 1.1 wt%<MgO<2.8 wt%,10 ppm<Y<14 ppm, 1.4 ppm<Yb<1.7 ppm, 450 ppm<Sr<1887 ppm as well as the average amounts of Sr/Y: 103.8, 10.5<(La/Yb)N<14.09 and 5.1<Yb/Lu<6.5. Thus, the overall geochemical data point to HAS characteristics of the rocks under study.  On normalized spider diagram to chondrite, MORB, and primitive mantle, all rocks demonstrate subparallel trend, linear and homogeneous REE profiles with LILE and LREE enrichment together Ta, Nb, and Ti negative anomalies. As the tectonic diagrams display, all the studied samples are plotted in an arc volcanic granite field formed in a subduction environment in an active continental margin. Moreover, all the obtained geochemical data point to a high silica adakitic magma as the parent magma.

The studied area lies in Alborz Mountain, which owing to the collision of two Eurasian and Arabian plates, where a Neo-Tethyan oceanic lithosphere (Southern Caspian Sea Ocean or SCO)” is subducted beneath the Central Iranian continental lithosphere (Salavati et al, 2013), is an active deformation zone. The studied rocks formed in arc and subduction zones setting. Adakitic rocks in the arc setting can be produced by partial melting of a hot and young subducted oceanic slab and subduction of a very young oceanic crust (<5Ma) at depths of about 25 to 90 km is required to produce adakitic magma in the arc setting (Thorkelsona and Breitsprecher, 2005). In the north of the investigated area and south part of the Caspian Sea, an Alpian oceanic belonging late Cretaceous age was reported and named “Southern Caspian Sea Ocean (Salavati et al., 2013), which was subducted toward the south. Adakitic activity and not-adakitic magmatism continued to migrate toward the trench supporting a slab window model. The proposed tectonomagmatic model "Ridge-Trench", indicates that the studied lavas were generated in the Neothetyan supra-subduction zone. Based on this model, in the south of Guilan Province, SCO oceanic crust (and likely its ridge) has subducted towards the south the first because of a pressure change that might be caused by the extension and thinning of the overlying crust. A slab window was formed therefore in the source region, and partial melting occurred by asthenospheric upwelling. It looks like the adakitic rocks imply a deep source with a low magma source melting degree.

The overall petrological and geochemical features of the studied lavas gave rise to the following conclusions A new group of extrusive rocks, with remarkable geochemical characteristics of adakitic rocks, is outcropped in the south of Guilan Province .These rocks are characterized by HFSE and HREE depletion relative to LILE and LREE and negative Nb, Ta, and Ti anomalies, suggesting the parent magmas were affected by subduction-related geochemical processes. On tectonic diagrams, the studied adakitic rocks plotted on an Active Continental Margin setting and they show HAS characteristics produced by 5% to 10% partial melting of an amphibolite garnet source from a hot and young Cenozoic slab subduction. All the geological and geochemical data indicate that the early Cenozoic adakitic magmas in the south of Guilan Province were generated in an extensional tectonic setting (Slab window setting) when the active spreading center of the Neo-Tethys oceanic (Southern Caspian Sea Ocean) subducted toward the south and produced a slab window. According to the proposed model, the active spreading center of the Neo-Tethys oceanic crust (Southern Caspian Sea Ocean) subducted toward the south and produced a slab window in the subducted oceanic lithosphere.

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.

Bahariyeh deposit is located in the central segment of the Khaf-Kashmar-Bardaskan magmatic belt (KKBMB), NE Iran. This belt is dominated by plutons of Kashmar batholith and associated volcanic rocks along the northern side of the Dorouneh Fault and is one of the most important metallogenic provinces in Iran. Based on geochemical data carried out for the purpose of the present study, the expansion of Cu and other metals mineralization is determined, and on the basis of investigation of trace and rare earth elements behavior, the genetic-lithological relationship of the intrusive rocks is determined in the North of Bahariyeh region.

Method of study:

 About 80 thin sections of intrusive rocks were prepared and 10 least altered 10 samples were selected and analyzed by X-ray fluorescence (XRF; PHILIPS PW 1480) at the Analytical Laboratory of the Kansaran Binaloud Institute of Mashhad, Iran. Also, 10 samples were selected for geochemical analysis by (ICP-OES) at the Zarazma Mineral Studies Co., Mashhad, Iran. Regional Geology Based on field observations a 1:10,000 geological map prepared from the study area, the existing rock outcrops mainly include an alternative of pyroclastic units, Eocene-Oligocene lavas, as well as subvolcanic and intrusive rocks. Field observations show the North of Bahariyeh area is composed of dacite-rhyodacite and andesite volcanic units, and has been intruded by granodiorite, quartz monzonite, monzodiorite-diorite porphyry. These acidic-intermediate intrusive masses have a granular texture and are mainly porphyroid, which have been affected by propylitic, siliceous, argillic, and sericitic alterations. Copper mineralization is observed in the form of veins in different parts of the region, the thickness of these veins varies from about 5 mm to more than 10 cm. Two types of vein-veinlets can be distinguished in the mineralization zone of North of Bahariyeh: 1) vein-veinlets containing quartz + chalcopyrite + specularite + pyrite; 2) specularite-rich veins. Petrography Granodiorite: Granodiorite shows a coarse-grained granular texture with graphic and myrmekitic intergrowths. The main minerals consist of plagioclase, K-feldspar (orthoclase), quartz, hornblende, and opaque minerals. The euhedral-subhedral plagioclase and K-feldspar phenocrysts have been altered to sericite, clay minerals, epidote, and chlorite.Monzodiorite porphyry: This unit has porphyritic and glomeroporphyritic textures with medium-grained groundmass. The monzodiorite porphyry contains up to 45-50 vol.% phenocrysts, consisting of plagioclase (15–20 vol.%), K-feldspar (10–15 vol.%), hornblende (5–7 vol.%), clinopyroxene (5–8 vol.%), and biotite (2–5 vol.%). The same minerals are also present in groundmass. Hornblende and biotite are replaced by chlorite in some places. Also, some plagioclase and feldspar phenocrysts have been altered to sericite, chlorite, and epidote.Quartz monzonite porphyry: The quartz monzonite porphyry has a porphyritic texture (0.1–0.2 mm) with a fine-grained groundmass and normally contains 40–45 vol.% phenocrysts that are 0.1–4 mm in diameter. It is mainly composed of plagioclase (30-35 vol.%), K-feldspar (25-30 vol.%), quartz (15–20 vol.%), and hornblende (5-10 vol.%). The same minerals are also present in groundmass.Diorite porphyry: This unit has porphyritic and glomeroporphyritic textures, with medium-grained groundmass with phenocrysts 0.1–5 mm across, and 40-50 vol.% phenocrysts including 25-30 vol.% plagioclase and 15-20 vol.% clinopyroxene and hornblende with minor biotite and alkali feldspar. The same minerals are also present in groundmass. Its accessory minerals are quartz, zircon, and magnetite (2–3 vol.% and 0.5 mm).

North of Bahariyeh provides important insights for reconstructing the Middle Eocene tectono-magmatic evolution of the NE of Iran. Significant outcomes of this work are:The intrusive sequence in the North of Bahariyeh is inferred as monzodiorite porphyry, diorite porphyry, quartz monzonite, and granodiorite of middle Eocene. and all intrusive rocks belong to I-type metaluminous-peraluminous granites. Major and trace element geochemistry indicate the acidic-intermediate intrusive rocks in the North of Bahariyeh were likely generated by partial melting from the subcontinental lithospheric mantle affected by both slab-derived fluids and lower continental crustal components.The enrichment of LILE (Ba, K, and Cs), depletion of HFSE (Nb, Ti), and the enrichment of LREE relative to HREE indicate crustal contamination and formation of the source magmas in a subduction environment zone by low degrees of partial melting. Trace element geochemistry confirms the evolution of dioritic rocks by a partial melting process (1-5%). Geochemical results, combined with regional geological data, demonstrate a shallow mantle with a clear subduction imprint (metasomatized mantle wedge melts). The post-collisional transtensional tectonic regime favored magma genesis with decompression melting and magma rise through the well-developed fault system and the subvolcanic and intrusive units in the North of Bahariyeh area form the active continental margin-related subduction zone.Overall, the data of the rare earth elements of acidic-intermediate units in the area of study shows that the rocks under investigation were originated by partial melting of enriched mantle under the influence of the fluids released from the subduction blade and then under the contamination of the crust.

The Cenozoic magmatism is mainly concentrated in the Alborz magmatic arc, Urumieh-Dokhtar magmatic arc, Central and Eastern Iran. The Western Alborz magmatic arc known as Alborz-Azerbaijan is hosted numerous porphyry-epithermal deposits. It is divided into Ahar-Arasbaran in the north and Tarom-Hashtjin metallogenic province in the south. The Tarom-Hashtjin metallogenic province is associated with several epithermal mineral systems (Ghasemi Siani and Lentz, 2022) related to Cenozoic magmatism. It consists mainly of intrusive, subvolcanic rocks, as well as volcanic-sedimentary complexes with acidic to intermediate composition. These rocks with calc-alkaline to shoshonitic nature, are predominantly granite, granodiorite, basalt, andesite, dacite, rhyodacite, rhyolite, and related tuffs. Th main goal of the present paper is to review the available data combined with our new data on the granitoids widespread in the area. An attempt is made to present the lithological, geochemical, and geo-structural features of the magma generated in Tarom-Hashtjin metallogenic province.

Regional Geology:

The Tarom-Hashtjin metallogenic province is limited by the Tabriz-Soltaniyeh (Northwestern part), Soltanieh-Takestan (Southeastern part), and Astara faults (Western part). Volcanic-pyroclastic rocks have been widely invaded by the Upper Eocene intrusive bodies (including Zaker, Marvarid, Koh-e-Tabar, Takestan, Zanjan, Tarom, Rudbar-Ahar, Vermarziar, and Goljin bodies). The epithermal deposits are classified as low sulfidation (LS), intermediate sulfidation (IS), and high sulfidation (HS).

Whole rock and isotopic geochemical data obtained from 176 samples of granitoid rocks related to 17 deposits (including 4 epithermal deposits of low sulfidation (LS), 5 epithermal deposits of intermediate sulfidation (IS), 4 epithermal deposits of high sulfidation) (HS) and 4 magmatic iron oxide- apatite deposits (IOA)). The data was compiled using Microsoft Excel (Appendix 1) and contains major oxides, rare earth elements and isotopic data, rock type, sources, and associated epithermal deposits. The samples of hydrothermal altered granitoid rocks with LOI greater than 2 percent by weight were excluded from the data set. Also, Sr-Nd isotopic compositions for 33 whole rock samples and Pb isotopic compositions for 24 granitoid samples are presented in Appendix 2.

Whole rocks chemistry:

Geochemistry of major elements: The amounts of some oxides including MgO, CaO, FeO, TiO2, and Al2O3 display negative  while the K2O content shows a positive correlation with increasing SiO2. The abundance of incompatible elements (i.e. Rb, Ba, Th, and Zr) increases slightly to moderately with increasing silica content. The amounts of P and Sr significantly decrease with increasing silica content. These granitoids are enriched in lithophile elements (LILE)(i.e. K, Rb, Th, U, Nd) and depleted in high field strength elements (HFSE) (i.e. Ta, Nb, Ti,) indicating the occurrence of magmatism associated with subduction and the characteristic of all magmas subjected to crustal contamination in subduction zones (Chappell and White, 1992; Wilson, 2007). Also, the investigated rocks are enriched in LREEs and depleted in HREEs (LREE/HREE = 1.14-10.34), a remarkable feature of magmas related to subduction zones (Wilson, 2007). The (La/Yb)N ratio ranges from 3.25 to 14.70 (ave.7.53). Isotope geochemistry: The studied granitoids are located in the ranges of magmas related to the subduction zone. These magmas are periodically contaminated by crustal materials. Most of the granitoid samples are placed within the depleted and enriched mantle array (Zindler and Hart, 1986).

The rocks under study associated with epithermal deposits in the Tarom-Hashtjin metallogenic province consist mainly of monzonitic, monzodioritic, quartz monzonitic, and granite belonging to high calc-alkaline to shoshonitic I type and metaluminous magmatism. They are characterized by Sr/Y (3.6 to 39.11), La/Yb (4.53 to 20.50) and high K2O values (with an average of 4.40 wt.%), consistent with calc-alkaline mantle melt contaminated by crustal materials (Chappell and White, 1992). Metaluminous and high calc-alkaline to shoshonitic igneous rocks are originated by partial melting of enriched lithospheric mantle metasomatized by fluids from the subducting slab. These granitoids also have Th values (average 15.17 g/t) higher than that of the rocks derived from primary mantle melt. Fluids and melts from the subducting oceanic crust metasomatized the mantle wedge above them causing a positive LILE and a negative HFSE anomalies.  Overall, the Tarom-Hashtjin metallogenic province is part of a back-arc extensional system arc behind the main Urumieh-Dokhtar main arc. Considering this, it seems that the extensional tectonic setting in the Lower to Middle Eocene was accompanied by convergence movements and was followed until the end of the Middle Eocene and Upper Eocene. This phase of extension occurred during the Eocene associated with slab rollback. The aforementioned tectonic movements can be associated with the processes of separation of the subducting plate or convective thinning of the lithosphere, causing the uplift of the asthenosphere and temperature disturbance in the metasomatism lithospheric mantle wedge. This disturbance gave rise to partial melting of the subducting slab and the lithospheric mantle wedge producing the primary potassic magma of the granitoid rocks under study. It suggests that primary source magmas were generated by partial melting of the mantle-wedge and were subsequently affected by both fractional crystallization and crustal assimilation during their magmatic evolution during Eocene magmas (37 to 42 Ma) in a back-arc basin.