petrology

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.

In the north of Jirandeh and east of Lushan, which are located in the mountains south of the central Alborz, a series of volcanic rocks are unconformablly located on the Middle Eocene limestone. These rocks have alkaline affinity of different types of lamprophyre and are studied for the first time from the petrology point of view. The texture of these rocks is porphyric to microporphic with microlithic matrix. The phenocrysts and microphenocrysts of the collected samples are generally olivine, alkaline pyroxenes and biotite, which are located in olivine, pyroxene, plagioclase, amphibole, very fine nepheline crystals, apatite and metal ores groundmass. Geochemical studies of these rocks indicate that these rocks are alkaline lamprophyres and the magma is the result of partial melting of an asthenospheric mantle source similar to OIB. They are classified in garnet lherzolite facies and were emplaced in an intercontinental rift tectonic environment.

Granites are interesting because of their abundance in the continental crust and the presentation of valuable information from the depths of the earth and their close dependence on tectonic and geodynamic processes (Bonin, 2007). The Mishu granites are exposed over an area around 50 km2 in the northwestern Iran near the city of Tabriz (Figures 1 and Figures 2). The Mishu granites have been injected into the Neoproterozoic shales, carbonates, sandstones, and tuffs of the Kahar Formation (Asadian et al. 1994). Mafic and ultramafic rocks (gabbro, basalt, and dunite) occur at the north and northeast of the Mishu granites and seem to be the host of granites. Field observations show a magmatic injection of the Mishu granites into the mafic-ultramafic rocks. There are several outcrops of granite rocks in the northwest Iran, including Takab–Zanjan, Khoy, Soursat, and Mishu. Among these outcrops, there are no systematic geochemical and geochronological studies on the Mishu rocks. In this paper, we investigate the genetic relationship between different parts of the mass, origin of the constructive magma and the tectonic position of this intrusion with the help of the results of field studies governing different parts of the Harris intrusion mass, petrography and geochemical analysis of the main and rare elements.

A total of 150 samples were collected from Mishu granites. Polished thin sections were prepared from all the collected samples.
Based on petrographic observations, 20 samples with minimal effects of hydrothermal alteration were selected for whole-rock geochemical analysis (Table 1). These selected samples were analyzed for major and trace elements at the ACME Laboratory (in the ACME Analytical Laboratories of Vancouver, Canada). Analytical errors for major elements are assessed as <1% of the determined concentrations. Results are reported in Supplementary Table 1. Major element oxide analysis was performed by Lithium Borate Fusion and Inductively Paired Plasma Emission Spectrometer (ICP-ES). In this method, the number of oxides of the main elements is measured based on weight percentage. The measurement accuracy for the main elements in this method was 0.01 Wt.%. Also, in this method, the number of volatiles in the form of L.O.I. was measured with an accuracy of 0.01%. The induced coupled plasma mass spectrometer (ICP-MS) method was used to measure the amount of trace and rare elements. The detection threshold of these elements, depending on the element, varied from close to 0.01 ppm to 10 ppm.

Harris granite rocks are in the northwestern Iran and about 20 km west of Shabestar city. This mass is composed of alkaline feldspar granite. The most abundant texture seen in these rocks is micro-pertite and myrmicite and based on lithographic and geochemical properties, they belong to A2-type granites. The samples are meta-aluminous to per-aluminous is based on the saturation index of alumina. In general, the studied granites have higher amounts of Na2O + K2O, Fe / Mg, Ga / Al, HFSEs and lower amounts of CaO, Sr and Eu. Also, the content of REEs of the samples in the normalized graph concerning chondrite shows a negative Eu anomaly. In other words, it is likely that A-type alkaline granites after collision have been created in this area following collision events and during their placement the tensile structure is predominant. Normalized multi-element diagrams as well as high Rb indicate that the continental crust has played a significant role in the formation of the Harris granite producing magma, possibly due to the melting of the lower crust by a tonalitic-granodioritic combination. 

All lithographic and geochemical data show that Harris granite rocks are of A-type nature. Negative anomalies of Ba, Nb, Ti, Sr and Eu and enrichment in LILEs, especially Rb and Th, indicate the crustal origin of these rocks separation of feldspar during crystallization or the presence of feldspar as a residual phase in the origin and the anomaly of P and Ti to iron-titanium and apatite oxides. Enrichment in LILE and HFSE elements with negative anomalies of Nb and Ti is a characteristic of subduction-dependent. The negative anomaly of Eu in the trace element pattern can be attributed to granites, usually attributed to the mantle origin, previously due to the metamorphic activity of fluids from sediments deposited by LILE and HFSE elements (Pearce et al., 1984), or may be the nature of magmas rooted from a subcontinent meteorite mantle formed during early subduction. In addition, enrichment at Th, Rb, and depletion at Sr, Eu, Ba, Nb, and Ti indicate that the granites are rooted in crustal lavas (Zhao and Zhou., 2007).

Alam- kuh granitoid intrusion is located in the western part of kelardasht, Central magmatic Alborz structural zone. Alam- kuh granitoid intrusion consist of alkaligranite, syenite, and syenodiorite to monzonite rocks. In the northern part of Alam -kuh intrusion, there are mafic enclaves that represent the magma mixing and mingling process. it consists of plagioclase, quartz, alkali feldspar and biotite minerals. Types of pertite and myrmekite textures associated with granular, microgranular and microgranular porphyry textures observed in these rocks. According to mineral chemistry and whole rock chemistry studies, intrusion rocks are I-type which are typically of shoshonites and are aluminous, metaluminous. Alam- kuh samples are shown enriched in light rare earth elements (LREEs), and La, Rb, Th, Tb elements and depleted in Ba and Zr elements. Based on the major element oxides, tectonically, located in the volcanic arc granitoids (VAG) .Primary magma of district igneous rocks were produced by the melting of the underlying crustal protolith (amphibolite) and (meta-graywacke ), and the basaltic magma derived from the mantle which replaced in the lower crust could be thermal origin for partial melting of crustal source and mixed with crustal felsic magma. According to studis, In the stretching environment of Alborz Magma Bow, Lithosphere mantle and stenospheric mantle, Both were involved in the birth of a mantle with different stocks. Mixing two magmas with mantle and crustal origins and subtraction and crystallization, The most important processes were the development of magma and the diversity of rocks in the region.

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.

Ahmadabad deposit is the northernmost old mine of Kuhbanan-Bahabad belt, located 10 km NE of Bahabad and is located in the stratigraphic sequence of calcareous-dolomitic Shotori formation. The predominant form of mineralization of Pb and Zn deposits in the region is of vein type, fissure, filling and substitution. Previous studies on the Ahmadabad deposit have considered the sedimentary genesis of the mineral to be sedimentary and the dolomitization to be due to the process of burial diagenesis in a lagoon environment. Due to the fact that the dolomites of the region are the main hosts of mineralization and a large amount of minerals are located in these rocks, the present study has focused on these rocks.

Dolomite-Carbonate units form the main volume of rocks in the area. Necessary information for investigating the genesis of dolomites was obtained from thin-polished cross-section, stable isotopic oxygen data and ICP-MS analysis, which was performed inside and outside Iran.

Microscopic studies show that dolomite crystals are formed in two stages and are visible with a gradual transition border and in some cases sharp border. The bright dolomites of the first stage darken in the next stage. Delayed dolomites are rhomboids with a sharp border and their outer part is covered by iron hydroxides. It is possible that the dolomites are oxidized due to stunted growth of Calcite cement within cavities bounded by dolomite, the presence of some calcite adjacent to dolomites, thick or thin zoning of the sharp boundary between calcite and dolomite, corrosion and dissolving at the junction, the presence of small amounts of Sulfides, oxides. Also, Cu-carbonates with lateral dolomite residues may indicate delayed formation of the oxidized margin of the dolomite. These features are compatible with the characteristics of hydrothermal dolomites in other parts of the world, such as hydrothermal dolomites southwest of the Cantabrian region of Spain. Isotopic data indicate the range of changes of δ18O-SMOW oxygen isotopic composition in the dolomitic rock of Ahmadabad deposit between 23.1‰ to 28.2‰. This value is close to the values reported in other hydrothermal dolomites of the world. The average values of δ18O-PDB in Shotori dolomites of Kuhbanan range are equal to -6.47‰. This value is also in the δ18O-PDB range of other hydrothermal dolomites. Comparison of Fe/Mg ratio in host rock and mineral also shows a 35-fold decrease in this ratio in the host rock. Studies have also shown the relative high level of deposit elements in the host unit. The available data indicate that Mg is used in the mineralization of hydrothermal fluids in the process of dolomitization of carbonate units. Hydrothermal fluids during mineralization have increased compared to poor Mg and its’ Fe content. Comparison of distribution patterns between minerals and rocks in the region shows an undeniable similarity between these minerals and carbonate rocks. The relationship  (  also reveals the increase and enrichment of rare earth elements in light to heavy types. The average ratio in carbonate units is 14.24. This ratio for minerals averages 14.63 and is very close to the average of total carbonates.

The findings of this study showed that the dolomites of the Shotori Formation in the study area were formed under the influence of hydrothermal solutions of metal-rich basins, which were also responsible for mineralization. Evidence from microscopic studies and stable isotopic data of δ18O-SMOW is consistent with the characteristics of hydrothermal dolomites in other parts of the world. The similarity of the normalized patterns of REEs in the host rock and mineral as well as the consistency of the variation in the ratio of Fe and Mg elements between the mineral and the host rock also confirm the result obtained. The similarity of the of the REEs of the host rock and mineral and the concordance of the ratio of Fe and Mg elements between the mineral and the host rock also confirm the result obtained.

Cenozoic acidic volcanic rocks at the south of Qezel Ozan River are located within the Western Alborz-Azarbaijan magmatic zone and northern part of the Iranian-Turkish Plateau. The Oligocene acidic lavas in north part of Zanjan show rhyolitic to dacitic composition.  Hyaloporphyritic to hyalomicrolithic porphyritic textures are the main texture in these rocks. They were erupted along the main faults in this area. Feldspars, biotites and hornblendes are the major phenocrysts which are embedded in a glass matrix or micro phenocrysts of felsic and mafic minerals. By Geochemical studies it is indicated that these rocks have high-K calc-alkaline to shoshonitic nature and classified as meta-aluminous and I-type acidic rocks. In the chondrite normalized rare earth elements diagram, these rocks demonstrate LREE enrichment and high LREE/HREE ratio. Enrichment in LREE and depletion in HREE is characteristic of the calc-alkaline rocks in active continental margins. Furthermore, these rocks show enrichment in LILEs and negative anomalies of HFSEs (Ti, Nb and Ta) which is the feature of magmatic rocks associated with Post-COLG subduction zones. The geochemical evidences suggest that the parental acidic magma is resulted from partial melting of lower crust as a result of pressure reduction during the local tension mechanism.

In the southwest of Khuni mountain and the north of Kal-e-Kafi intrusion (northeast of Anarak), the igneous rocks of Khuni are cropped out. They dominantly show porphyritic texture and are similar to monzodiorite in composition. The phenocrysts mainly are clinopyroxene (diopside), amphibole (magnesiohastingsite to magnesian hastingsite), and feldspar (orthoclase in the rim and andesine in the core). Accessory minerals include primary biotite, apatite, sphene, and magnetite. The secondary minerals are biotite, calcite, epidote, tremolite- actinolite, and chlorite. Anti-rapakivi texture in feldspar is petrographic evidence of magma contamination. Application of various geothermobarometric methods for clinopyroxene and amphibole crystals in Khuni rocks yielded a crystallization temperature of ~1150°C for clinopyroxene and pressure range of 7-8 kb and temperatures of ~900-950°C for the amphibole phenocryst. Thermobarometry and chemistry of clinopyroxene and amphibole phenocrysts indicate that the rock-forming melt was formed by melting the continental crust in the Anarak area, as a result of the subduction-related magmatism of Eocene during the Neo-Tethys subduction beneath Central Iran.

The mafic- ultramafic intrusion in the Bafq anomaly Iron located 35 Km northwest of Bafq city, Central Iran. The 15th anomaly intrusion intruded the Rizu sequence series, stratigraphically attributed to early Cambrian magmatism in the west of Posht-e- Badam block. The Rizu sequence series is composed of carbonate rocks of upper Neo-Proterozoic-early Cambrian. The mafic-ultramafic intrusion is dominated by amphibole-gabbro, apatite- gabbro, anorthosite- gabbro, amphibole- pyroxenite, apatite-pyroxenite with predominant granular texture and cumulate characteristics. The associated main mineral assemblage composed of cumulate predominantly clino-pyroxene, Fe-Ti oxides, calcic plagioclase, amphibole, apatite, as well as minor olivine. The intrusion formed from mafic magma and differentiated from tholeiitic to weakly calc-alkaline affinity. Spider diagrams of the analyzed samples were normalized to the standard values of chondrite and primitive mantle. REE– normalized diagrams are characterized by LILEs enrichment and HFSEs depletion and mild negative REEs trend. Different tectonic setting discriminative diagrams and elemental ratios are indication of a subduction related affinity. The parental magma could be generated by melting of mantle peridotites (lithospheric mantle) which previously affected by subduction related fluids. The results of this research is consistent with the previous models which considered the Early Cambrian magmatism in Post-e-Badam block related to the subduction of Proto- Tethys oceanic crust beneath the Central Iran in the north of Gondwana land.

West and south west of Razan igneous rocks are located in the Hamedan Province in the Sanandaj- Sirjan zone, west Iran. According to petrography and chemical studies, these rock bodies are composed of diorite, gabbrodiorite, monzonite, quartz- monzonite, andesite and andesibasalt. The results of geochemical analysis show that these rocks belong to a cal- alkaline magma series. The geochemical charactersistics of the rocks in this area have been affected by the magmatic processes such as fractional crystallization, assimilation, rate of partial melting and composition of original rock. Patterns of trace and  rare earth elements normalized to Chondrite and primitive mantle show that LREE contents are sharply higher than HREE. The magma of the intermediate-basic igneous rocks in the west and southwest of Razan have formed in a subducthon zone and volcanic arc active continental margin.

The study of petrological findings and geochemical data of mafic and ultramafic rocks and related petrographic units in the ophiolites can be an introduction to environmental geology studies, agriculture and natural resources. Regarding the urban and rural areas of Nain to Ashin in the vicinity of ophiolitic zone (Central Iran), geochemical investigations of mafic and ultramafic rocks of these ophiolites have very important applications in the field of environmental geology of these areas. Therefore, available geochemical data of basic rocks (pillow lavas and basalts), metabasic rocks (amphibolites) and metamorphosed and altered peridotites are considered based on environmental factors. For examples, in the peridotites which are one of the most abundant rock units in these ophiolites, the enrichment factor (Ef) for Ni is extremely high, for Cr is very high, and for Co is high. In addition, the geo-accumulation index or Igeo for Ni (~4) and Ni (>5) in peridotites is heavily to extremely high. therefore, high Ef and Igeo factors of the studied heavy metals (e.g., chrome, nickel, cobalt, arsenic, vanadium) and asbestose minerals (hornblende, tremolite, talc and chrysotile) in the mafic and ultramafic rocks of Ophiolites can be known as some dangerous environmental pollutants. Thus, investigatation of the volume of such elements penetrated into the surface and underground waters and soils in the villages and cities at the foot of these ophiolites could be a theme for ongoing studies in environmental geology of these areas.

The Rangraz copper deposit is located in 18 km of northern Saveh which is in the central part of the Uromieh–Dokhtar magmatic arc. The host rocks are mainly volcanics and volcaniclastics of Eocene which altered and mineralized by intruding the quartz monzodiorite intrusion and andesitic-basaltic dikes in them. Hydrothermal alterations are propylitic, sericitization, silicification, and the chlorite-clay minerals-quartz assemblage. The principal hypogene ore minerals include pyrite, chalcopyrite, bornite, specular hematite, and magnetite. The Rangraz quartz monzodiorite composes of plagioclase, K-feldspar, quartz, fine grain biotite and amphibole shows granular to porphyritic textures. These rocks are commonly metaluminous and calc-alkaline. The high CaO (2.61 to 5.81) and Na2O (6.90 to 7.78) and low K2O(0.04 to 0.38), Fe2O3 (2.60 to 4.58), and MgO(1.22 to 2.81) contents can be caused by the extensive propylitic alteration in intrusion rocks of the study area. According to the tectonic setting discrimination diagrams, and trace and rare earth elements distribution patterns, depletion of Ti, P and LREE enrichment are the subduction at active continental margin tectonic characteristics. Significant negative Eu anomalies and relative depletion in Sr indicate the presence of plagioclase as a stable phase at magmatic source. The result of petrogenetic studies represent that crystal fractionation, and magma mixing were the most dominant processes controlling magmatic evolution.

The Ghoshchi granitic rocks are located in at north of Uromiyeh city and are mainly composed of alkali-feldspar granites, granites and aplitic dykes. These samples belong to calc-alkaline to shoshonitic series and show Fe enrichment and are classified as A-type granites. Ghoshchi granites have high K2O㖭, FeO/MgO, Gl/Al, Ce/Nb, Zr, Y/Nb, and low CaO, Ba, Sr and Eu and are A2-type granites. Geochemical and Sr-Nd isotopes evidences suggest that these rocks were generated by highly fractional crystallization of a parental magma (melts), was derived from an enriched mantle source, which have undergone contamination by crustal materials and formed in post-collisional extentional environments in a within-plate setting. The crystallization age of these rocks, according to biotite 40Ar-39Ar and Rb-Sr dating is 262±26 Ma and 256±20 Ma, as minimum age, respectively, and 320-330 Ma as crystallization age. Ghoshchi granites formed probably within extentional zones in at the late stages of Variscan tectonic events.

Studied area which is introduced as Ayoub Ansar volcanic dome, located about the 25 km southeast of the Takab, in the central part of the Takab 1:100000 geological map. This area is a part of Central Iranian Zone at the junction of Sanandaj- Sirjan and Central Iranian Zones. Ayoub Ansar volcanic dome intruded into the marl and sandstones of Miocene. In this base, post Miocene age could be considered to it. This volcanic dome croups out in E-W trend with length about 4.5 km and 2.5 km width. Based on petrographic studies, Ayoub Ansar volcanic dome has dacitic- rhyodacitic composition. These rocks have porphyritic, felsophyritic and golmero- porphyritic texture with plagioclase, Amphibole and quartz phenocrysts. Based on geochemical evidences, these rocks are high- K calc-alkaline, metaluminous to peraluminous and classified as I-type granitoids. These rocks demonstrate REE patterns with enrichment in LREE, high LREE/HREE ratio and without negative Eu anomalies which indicate that plagioclase didn’t underwent fractionation. Enrichment in K, Rb and Ba and negative anomalies for HFSEs such as Nb, Ta and Ti in the spider diagrams indicative for influence of the continental crust in formation of parent magma. Based on tectonic setting discrimination diagrams, these rocks formed at the volcanic arc and Syn-collisional to post- collisional setting. The studied dacites demonstrate geochemical features like Adakites.

Khanchay-Aliabad area as a part of Tarom magmatic belt contains some shallow depth intrusions which are intruded the Eocene volcanic- sedimentary rocks and have very close association with Cu mineralization. The Eocene volcanic- sedimentary rocks include alternation of basalt, basaltic andesite and andesite, various kinds of tuff, tuffaceous sandstone, sandstone, siltstone and occasionally shale. Petrographical studies demonstrate that intrusions are pyroxene quartz monzonite and olivine gabbro in composition. The Khanchay pyroxene quartz monzonite have porphyritic to porphyroidic, hetero-granular to sereitic, ophitic and sub- ophitic textures and composed of plagioclase, clinopyroxene, hornblende, quartz, K-feldspar and biotite. The Aliabad pyroxene quartz monzonite shows porphyritic to porphyroidic textures composing of plagioclase, clinopyroxene and hornblende in the quartz- feldspatic matrix. The Khanchay olivine gabbro is characterized by the presence of coarse grained granular, ophitic and sub- ophitic textures as well as the occurrence of plagioclase, clinopyroxene and olivine. Geochemical studies indicate that the Khanchay- Aliabad pyroxene quartz monzonitic intrusions have SiO2 content varying from 59.58 to 61.34 %. These intrusions have high- K calc- alkaline nature and are classified as I-type metaluminous granitoids. Their similar patterns on spider diagrams are indication of genetic relation of these intrusions. On these diagrams LILEs (Ba, K, Th and Pb) enrichment along with negative anomalies of HFSEs (Nb and Ti) are observed. Moreover, the Chondrite normalized REE patterns demonstrate LREE enrichment with high ratio of LREE/HREE and Lan/Ybn ratio ranging from 3.08 to 3.72. The overall field investigation, petrological and geochemical studies as well as tectonic setting discrimination diagrams confirm that the Khanchay- Aliabad high-K intrusions were formed from a subduction related metasomatized lithospheric mantle in a post- collisional setting.

The Tannurjeh porphyry Au-Cu prospect area is located in the northeastern Kashmar, the Khorasan Razavi province, and central of the Khaf-Kashmar-Bardaskan magmatic belt. Geologically, the area is dominated by the Tertiary rhyolitic-rhyodacitic volcanic rocks, which are intruded by monzonitic to dioritic subvolcanic intrusive rocks. The texture in the most of the study igneous rocks is porphyry with fine groundmass and the main minerals are plagioclase, alkali feldspar, quartz, biotite, hornblende and magnetite. The monzonitic intrusions are the source of widespred mineralization and alteration, whereas the diorite is the later phase, which is devoid of mineralization. Using zircon U-Pb method, the age of monzonitic intrusive was determined at 39.8 Ma (Middle Eocene), geochemically as well as mineralogically, the igneous rocks of the area are calc-alkaline granitoids belonging to magnetite series (I-type) which were developed in subduction tectonic setting. The LREE enrichment relative to HREE and enrichment in K, Rb, Cs, Th, and U in comparison to Ti and Nb elements are observed in all of the samples studied. Eu negative anomalies and low Sr/Y ratios can be attributed to the presence of residual plagioclase in the source. (87Sr/86Sr)i (0.705673 and 0.705158), (143Nd/144Nd)i (0.512524 and 0.512570), and εNdi (-1.22 and -0.32) values indicate magma is derived from mantle wedge above subducted slab, which is assimilated with upper crust. Finally, the Eocene is an important metallogenic episode, particuarly for Au and Cu, in NE of Iran.

In the southwest of the Qorveh area, north of the Sanandaj-Sirjan zone, there are outcrops of acidic and intermediate rocks including monzogranite, granodiorite, tonalite and diorite. According to petrographical studies, plagioclase, alkali-feldspar, quartz, amphibole, clinopyroxene and biotite. Geochemical and mineralogical studies indicate that these rocks are metaluminous to some peraluminous, belonging to calc-alkaline magma series and having I-type characteristics. The REE normalized chondrite pattern of the samples show the M-type tetrad effect and relatively negative Eu anomalies. All of petrography and geochemistry data show fractionation crystallization REE-enriched minerals e.g. feldspar, amphibole, apatite and titanite followed by magma-fluids reaction in late crystallization phenomena are the most important factors for the formation of tetrad effect in these rocks. Lanthanides tetrad effects are recognizable in REE patterns of the samples and they change versus Y/Ho, K/Rb, Zr/Hf, Sr/Eu and Eu/Eu* ratios in accordance with evolution trend of granitoid. These rocks are enriched in LILE (i.e. U, Rb, K, Th) and LREE and show some depletion in Nb, Hf, Ti, Ta, Ba, Zr and P. LILE and LREE enrichment and HSFE depletion of the samples are indication of their formation in subduction zone

Hamyerd iron deposit is located about 74 km north east of Semnan, in the Jam area. This area is situated in the northern part of Central Iran structural zone. The outcrops are Middle-Eocene volcanic and pyroclastic rocks with andesite to andesite-basalt and tuff composition, which are intruded by some intrusive bodies of monzonite to monzodiorite composition in this area. Iron mineralization is occurred at the contact between intrusive bodies with volcanic rocks. Widespread presence of hematite with minor contents of magnetite, pyrite, barite, and calcite is the main characteristic of mineralization in Hamyerd deposit. Mineralization is occurred as veins and lenses of hematite with leser amounts of magnetite. According to geochemical properties, the sub-volcanic intrusive body of Hamyerd is calc-alkaline and high K calc-alkaline and meta-aluminous in nature, belonging to I-type volcanic arc granitoids. Enrichment of LIL elements compared with HFS and negative anomaly of Nb and Ti and the samples plot within the VAG field suggest that the sub-volcanic intrusive body of Hamyerd has formed in a volcanic arc environment, related to the subduction zone.