منصور قربانی

The studied intrusive bodies have penetrated into the Neoproterozoic amphibolites, mica schists and gneisses in the east and center of Muteh-Golpayegan metamorphic complex, within the central part of Sanandaj-Sirjan zone, in the vicinity of Urumieh-Dokhtar magmatic belt. Due to the deep normal faults formed in these transtension zone, Muteh rocks display mylonitic fabrics and overprinted by cataclastic deformation. The composition of these rocks is mainly leucogranite and the deformational indicators are observed in the both outcrop and microscopic scales in this shear zone. U-Pb geochronology of 3 samples from undetermined outcrops suggest that these rocks have crystallized during the Neoproterozoic (Ediacaran) time. Based on geochemical characteristics, the rocks belong to high-K calc-alkaline series and are peraluminous and ferrous granitoids with S-type affinities. Muteh-Golpayegan metamorphic complex is a part of Cadomian magmatic arc in which leucogranites are formed from partial melting of meta sedimentary rocks due to injections of mantle melts.

The Marphioon pluton in the southwest of Neyasar city and central part of Urmia-Dokhtar magmatic arc is among the Neotethyan oceanic lithosphere subduction-related intrusions. We used field evidences, petrography, geochemistry and U-Pb geochronological and aeromagnetic data to suggest a tectonomagmatic scenario for the intrusion. The composition of this circular pluton that has intruded into the Eocene volcano-sedimentary units changes from intermediate rocks to more tonalitic ones. The Marphioon granitoid gives rise to contact aureole zone with different peripheral thicknesses. U-Pb geochronology of a sample from southern part of the pluton suggests that these rocks have crystallized at 18.89±0.20 Ma in Early Miocene (Burdigalian). The rocks belong to medium-K calc-alkaline series and are metaluminous with I-type affinities. In terms of geodynamic setting, this intrusion is classified as volcanic arc granites and active continental margin granites. Qualitative interpretation of aeromagnetic data suggested a dioritic to gabbroic composition due to high magnetic susceptibility. The Marphioon intrusion is strongly tectonized due to faulting. Basement dextral strike-slip faults and their sinistral conjugates are potential mechanisms for its exposure. The pluton appears as two or three segmented bodies due to the presence of minor faults. Based on the aeromagnetic data this intrusion has a dip towards the northeast. It seems that the Marphioon magma in an active continental margin, originated from the partial melting of the lower continental crust with the involvement of mantle-derived melts, where mafic magma in mantle wedge has provided optimal temperature and fluids for this melting in the lower crust. Collectively, the Marphioon intrusion seems to be emplaced during the transition time from subduction to collision in the Urmia-Dokhtar magmatic arc contemporaneous with the closure of the Neotethyan Ocean.

The Kahdelan area in the SW of Sarab is situated in the northern part of the Urumieh–Dokhtar geotectonic zone and Tarom-Hashtjin metallogenic zone. Some of the most important porphyry Cu ± Mo ± Au mineralizations in Iran occur along the NW–SE trending Urumieh–Dokhtar volcano-plutonic belt, lying between the Sanandaj–Sirjan zone and Central Iran. The Urumieh–Dokhtar magmatic arc, extends over a strike length of about 2000 km from northwest to southeast and is characterized by subduction-related calc-alkaline rocks. Due to extensive Tertiary magmatism and extensive alterations, this zone is one of the remarkable Cu-bearing regions in Iran. Therefore, many studies, regarding different aspects of the area, have been carried out by the Geological Survey of Iran as well as some private companies. Differentiating fertile and barren intrusive bodies could be important factors in reducing exploration expenses, and it is possible to identify susceptible areas by using geochemical data. Thus, the main purpose of the present study is to evaluate the granitoid rocks of the Kahdelan area as the possible potential for Cu-mineralization based on mineralogical and geochemical evidence.

Regional Geology:

The main intrusions of the Kahdelan area are Oligocene granitoid bodies composed of syenite, quartz syenite, and monzosyenite with light color and granular texture. Syenites are the most dominant plutonic rocks and quartz-syenites are the main host of Cu-mineralization. These intrusive bodies intruded the Upper Eocene pyroclastic and volcanic rocks which gave rise to alteration and mineralization occurrences in the area. Volcanic rocks are composed of basalt, basaltic-andesite, andesite, and trachyte mainly with porphyritic texture.

The present study evaluates the copper mineralization potential of the Kahdelan area for the first time. The represented information can be divided into three parts: 1) ore mineralogy and mineralogy of the Kahdelan’s rocks; 2) the investigating data related to I-type and magnetite series, and 3) the relationship between the obtained mineralogical and geochemical data with Cu-mineralization in the area to compare with porphyry copper deposits along the Urumieh–Dokhtar magmatic arc.

The dominant alteration zones in the area under study are argillic, phyllic, carbonatization, silicification, and hematitization. The primary ore minerals are magnetite, chalcopyrite, and bornite which are generally replaced by secondary minerals including chalcocite, covellite, and malachite. The ore textures are predominantly disseminated, open space-filling, replacement, and brecciated. Gangues (carbonate and quartz minerals) textures are crystalline, open space-filling, cementation of brecciated zones, and colloform.The volcanic rocks of the Kahdelan area are calk-alkaline to shoshonitic and the granitoids are shoshonitic affinity and I-Type nature (magnetite series). In the area of study, sinking solutions washed away most of the pyrites and left behind empty pyrite molds and iron oxides and hydroxides along with different amounts of malachite and neotocite. As the chondrite-normalized REE diagrams display the studied granitoids are enriched in LREEs and fairly depleted in LREEs relative to HREEs The enrichment of LILE elements and depletion of HFSE elements are features similar to those of the fertile granitoids. The rate of decline of the slope in the diagram is similar to that of the copper porphyry deposits also slightly negative Eu anomalies of these granitoids are similar to fertile granitoids (Karimpour et al., 2021). The (La/Yb)n and Eu/Eu* are used in evaluating the oxidation state and investigating the depth changes of parent magma of granitoids. The (La/Yb)n anomalies vary from 4.05-23.17, and Eu/Eu* anomalies vary from 0.32-2.65 with an average of 0.8 that are different from copper porphyry deposits.Based on spider diagrams, the depletion of titanium could be related to the low oxygen fugacity in subduction zones. The Pb and U enrichment point to the role of the earth’s crust in the petrogenesis of these rocks. P depletion could be the consequence of apatite crystallization from the parent magma.Based on the relationship between geochemical data as well as mineralization, three diagrams have been used to distinguish fertile granitoids. The Eu/Eu* versus (La/Yb)n diagram (Karimpour et al., 2021) shows that Kahdelan’s granitoids have a reduced nature. The SiO2-K2O diagram (Peccerillo and Taylor, 1976) points out that the intrusive and the volcanic rocks of Kahdalan are characterized by the much less SiO2 amount compared to fertile granitoids in SNJMB (Saveh-Nain-Jiroft Magmatic Belt) (Karimpour et al., 2021). On A/NK versus A/CNK diagram (Meinert, 1995) the granitoids under study are close to fertile copper porphyry deposits.

On the basis of mineralogical and geochemical data, Kahdelan’s intrusive rocks are I-type and magnetite series. The tectonomagmatic setting of the rocks under study lies within Volcanic Arc Granites (VAG), active continental margins, and arc systems. On A/NK versus A/CNK diagram, these granitoids are close to fertile copper porphyry deposits. Quartz syenites are the main mineralization hosts. Based on geochemical data, the average Cu content is 3492.76 ppm in a total of 170 samples collected all over the area and up to 230534 ppm Cu in mineralized Quartz syenites veinlets. Mineralogical, geochemical, and alteration data in combination with fertile–barren discrimination diagrams indicate that the granitoids of the Kahdelan area can be evaluated as the possible potential for Cu mineralization.

The Iron-apatite deposits of Choghart and Chadormalu mining district are located in the western margin of the Bafq block and are hosted by Precambrian metamorphic basement complex, Late Precambrian sedimentary-volcanic units, and Late Precambrian-Early Cambrian plutonic rocks. The origin and relation of the rocks for a long time, which are known as metasomatites, have always been questioned. Based on petrography and mineral chemistry studies, five types of hydrothermal alterations have identified in these rocks. The oldest one is Na-alteration, which occurs at farther distances of iron deposits and is characterized by the presence of chessboard albite. The youngerst one is sodic-calcic alteration which is widespread and two-stages of the metasomatism model are characterized by the presence of tremolite-actinolite and is synchronous with the Fe-oxides. Potassic alteration occurs after two previous alteration phases, because of the influence of K-rich fluids and the formation of K-feldspar and secondary biotite. Silicate and sericite alteration has occurred as a late phase in the region.

The study area is located 12 km south of Zahedan city, Sistan and Baluchistan province. Rock units in this area include a series of slightly altered flysch facies units with Eocene age, subvolcanic rocks and basic to intermediate dikes with probably Oligocene-Miocene age. Subvolcanic rocks in the form of stocks and domes intruded into the flysch unit and were cut by intermediate dykes in the later stages. The subvolcanic units of the region have two main compositions diorite-monzodiorite and quartzdiorite-quartzmonzodiorite with porphyry texture. The subvolcanic units of this area are in the range of metalalumin to slightly peralumin and I-type. This is consistent with the evidence such as the widespread presence of hornblende, apatite and sphene in the studied subvolcanic units, which indicates the oxidic conditions and high oxygen fugacity for these rocks at the time of formation. Spider diagrams drawn for trace and rare earth elements show the single origin and the role of fractional crystallization in the formation of these rocks. Based on the spider diagram of rare earth elements, the studied subvolcanic units of LREE elements show a enrichment toward to HREE elements, which is one of the prominent characteristics of calc-alkaline rocks in the subduction zones of the continental margin. These rocks are placed in the tectonomagmic environment diagrams in the adakitic range and in the category of shoshonite and high potassium calc-alkaline rocks, related to subduction environments.

Takab-Mahneshan's metallogenic area is essential in gold mineralization, and it is a part of the northern Urmia-Dokhtar magmatic belt. The northern Urmia-Dokhtar has two distinctive features. It contains the Precambrian basement, and the young Mio-Pliocene magmatism rocks overlie its Precambrian basement. Precambrian basement has two different compositions, oceanic and continental crusts (gneiss, granite, mica-schist, greenschist, amphibolite, serpentinite, marble). The Young rocks are composed of hyaloclastite, acidic tuff, andesitic-basaltic, acidic to intermediate intrusions (diorite, granite), limestone, and marl of Qom formation. We categorized the Young rocks into four phases based on their age and positions. The mutual effect of the basement and young magmatism --in the latest phase --creates hydrothermal solutions in the form of a heat engine. The heat engine has caused rotation and variety, increasing mineralization in the area. As a result, there are mines, deposits, gold indications, and some associated gold elements, including Tuzlar, Bayche Bagh, Baghcheh at Mahneshan area, Zarshuran, Agh-darreh, and Ay-Qalesi in Takab. The Tuzlar and Baghcheh deposits with gold mineralization are in a Silicic-argillic zone, including pyrite, gold-bearing silica, argillic and ferrous hydroxides minerals. The Ay-Qalesi polymetallic deposits often contain zinc and lead. The Zarshuran and Agh-darreh deposits are the gold types that the first one has a variety of mineralization of sulfides and sulfosalts. The second one has simple gold mineralization, and finally, the Bayche Bagh deposit with polymetallic type includes chalcopyrite, pyrite, rutile, arsenopyrite, sphalerite, bornite, smaltite, chloanthite, azurite, and malachite minerals.

Iran is important in terms of non-metallic mineral resources in the world. Iran is ranked among the top ten countries in some sources of non-metallic minerals such as fluorspar, industrial soils (kaolinite), feldspar, silica and celestine. Iran›s non-metallic mineral reserves are significant. Iran is one of the largest holders of feldspar reserves in the world. So far, based on the limited discoveries made in Iran, barite reserves are about %13 and garnet, fluorspar and celestine reserves are about %1 of the total world reserves. The share of Iran›s non-metallic mineral production compared to the world in recent years includes 25 percent of celestine, 8.5 percent of feldspar, 4 percent of kaolinite, 2.6 percent of barite, 2.3 percent of bentonite, and about 1 to 2 percent of fluorspar, aluminum silicates, and talc. In terms of exports of non-metallic minerals, including bentonite, Iran ranks 10th, aluminum silicates 11th, feldspar 12th, and fluorspar 13th in the world. Considering the amount of resources and reserves of non-metallic minerals in Iran, their production and export can increase with the development of extraction and processing. Therefore, in addition to meeting its needs, Iran can be one of the top exporters of these products and minimize its imports of these products.

The Ay Qalasi Pb-Zn (Ag) epithermal deposit is located in the south east of Takab, northwest of Iran and is formd at the Urmia-Dokhtar magmatic belt and the Sanandaj-Sirjan zone intersection. Based on microscopic and EPMA analysis, the composition of this series is tennantite-tetrahedrite. These minerals are mainly replaced in host minerals. The EPMA analysis data show that their chemical composition is a function of the mineralogical composition of the sulfide ores in which they have been replaced. Tertiary dacitic domes replacement adjacent to the deposit has led to the formation of hydrothermal solutions with high fugacity of sulfur and arsenic, and to a lesser extent antimony. Due to the fault's reactivation, the initial sulfide minerals to be brecciated and provides the conditions for the penetration of these fluids. The penetration and circulation of these fluids in the brecciated parts of the deposit, due to the high fugacity of sulfur and arsenic, impose new thermodynamic conditions on the system, which in turn leads to the instability of sulfide minerals. In the new condition, the clasts of sphalerite, chalcopyrite, and pyrite ores react with these fluids to form sulfosalt minerals of tennantite-tetrahedrite series.

Iran has an area of 1,648,195 square kilometers, which is about one percent of the global land: considering its population of about 80 million people Iran, around one percent of the world's population live in Iran. Existence of special geological features such as multiple phases of tectonomagma, metamorphism and sedimentary basin changes from the Late Precambrian to the present has caused this land to have different igneous-metamorphic and sedimentary zones, each of which has its own deposit characteristics. These special features have led to the presence of more than 70 types of minerals and fossil fuels in this country, so that about 5% of the world's minerals, 10% Oil, 16% gas and 1% of the coal of the globe are formed in this country.

Our country Iran, during its several millennium civilizations has advanced in exploring minerals, using minerals and mining skills. Hundreds of ancient mines containing gold, copper, iron, lead, zinc, silver and so on has been discovered up to now. Some of them were active for hundreds of years. Many mineralogical workshops, mining tools, melting shops, and housing sites have been discovered in Iran that date around 4000 BC. From the beginning of the third millennium BC, Iranians prowess in mining and use of metals is mentioned in Sumerian, Babylonian, and Elamite documents. In all historical eras of Iran from prehistoric, to ancient history and Islamic periods mining, its exploration skills and extraction methods were present and remarkable. Huge amount of mining Relics in museums are testimonials to this fact. Lack of dense vegetation, and interaction between multiethnic societies who lived in Iranian plateau made them expert in mining and the usage of the minerals way before the industrial revolution in Europe. Their mastery in mining has been so advanced that even today’s miners find it inspiring and are in awe regarding their knowledge and prowess. Surprisingly, we cannot find too many new metallic deposits that our ancestors didn’t knew about them. For instance most of our gold, copper, lead & zinc and iron mines that are active today are the same ones that were exploited during Achaemenid, Arsacid and Sassanid Empires. Being rich in metals and ores along with the ancient civilization the people can claim that they have a country with the oldest history of metalworking. Due to the all mentioned above, it’s not incorrect to say that Iranians were the pioneers of mining in the world.

In this investigation, the Maastrichtian deposits in the west of Fars area, have been studied along a NE-SW trending transect perpendicular to the Zagros. The Maastrichtian deposits in Fars area show a shallowing-up trend from pelagic marls and turbiditic facies of the Gurpi/Amiran Formations, outer-mid platform carbonates of the Tarbur Formation and restricted inner platform dolomitic/evaporitic limestones and marls of the lower Sachun Formation. On this basis, 12 facies types have been determined in 6 facies belts from basin to barrier, open and restricted lagoon and tidal flat in a carbonate rimmed shelf setting. These sedimentary facies and environments are organized in five 4th order depositional sequences. The sequence architecture shows a migrating foreland basin with a wedge-shaped geometry along the transect. The foreland basin is characterized by wedge shaped geometry and the subsiding and shallowing up depositional sequences with progradational patterns from the platform carbonate over the pelagic basinal facies.

Ali abad chromites mines (north east of Forumad) are as a part of chromites assemblage dependent on ophiolite Sabzevar that are located in NW Sabzevar city. Chromitites deposits in these mines have been located as irregular lenses and layered or banded along with pods of dunite in depleted harzburgite. In attention to mineralogy observation, incongruent melting of orthopyroxenes and exsolution lamellae of clinopyroene in the orthopyroxenes, indicate that these rocks were originally formed at mantle pressures and temperatures conditions. Mineralography study on the textures and structures of Ali abad chromites indicate two types main textures that are primary and secondary. The primary textures and structures include massive and disseminated or separated grain. The milonitic, brecciated and tensional textures are from secondary types in chromites. On the basis of geochemical results the structural formula are calculated as the chromite minerals [(Mg,Fe2+)O (Cr,Al,Fe3+)2O3].These studies represent height percent Cr2O3 chromite mineral in disseminated texture than massive textures. Geochemical study on the chromitite area, site them in height Cr types and associated to podiform type that are originated from a parent melt with boninitic character resulting from high degree of partial melting of mantle peridotite in Supra Subduction Zone (SSZ).

Late Cretaceous in Zagros encompasses regional tectonics and caused foreland basin to form in northeast of the Arabian Plate. Salt tectonics is also locally affected this area. One of the time periods that can better picture this tectono-sedimentary evolution is Maastrichtian. In order to investigate this evolution in the Maastrichtian time, a regional cross-section was made inthe Fars outcrops and wells. A sedimentological study and sequence stratigraphy have been accomplished along this transect. Maastrichtian deposits consist of the upper part of the Gurpi and the Tarbur formations in the studied transect. Based onsedimentological investigation, 14microfacies have been identified. This microfacies were deposited in 4microfacies belt including tidal flat, restricted and open lagoon, reef and open marine in a shelf carbonate platform. Based on sequence stratigraphic studies, 3 sedimentary sequences were identified in the studied interval. Correlation along the transect revealed that the Maastrichtian deposits occurred on the forebulge of Zagros foreland basin. It is also concluded that the fore-buldge shows a nearly smooth topography and thus accommodation space is homogeneous. Hence the thickness of the Maastrichtian deposits does not vary so much along this transect. Thickness anomaly in Namak-dehkuyeh occurs as a result of salt structure which decreased accommodation space.

Hormuz Island at the entrance of the Persian Gulf and Oman Sea is a symbol of Iranian diapirism and the Hormuz series. In considering the location of the island and the development plans for Hormuz Island, it is important to know the composition and characteristics of the island's coastal sediments. This study was conducted to study the sedimentary, mineralogical, and geochemical properties of the coastal sediments of this island. For this purpose, In this study, 20 thin sections were made from gravelly rock samples as well as 27 surface sediment samples from nine stations has been collected. Routine sedimentologic tests have been done on these samples including quantitative mineralogy by XRD, separation, and identification of heavy minerals using bromoform solution and magnetic property, heavy metals and primary oxides were analyzed by XRF and petrographic study using a polarizing microscope. The results indicate that the sediments are sandy to gravel in terms of grain size. The average amount of calcium carbonate is 32 to 62 percent. The mineralogy of sediments shows that suite of calcite, quartz, feldspar, plagioclase, dolomite, aragonite, clay minerals (Kaolinite and Illite) and heavy minerals (magnetite, hematite, oligiste, epidote, pyroxene, pyrite, goethite, limonite, apatite, barite,) are other components of superficial sediments. The study of thin sections under the polarizing microscope shows that most gravels on the coast have an igneous origin (rhyolitic and trachytic). The findings of this study indicate that the main source of these sediments is the alteration and erosion of the Hormoz Serie (the Late Precambrian–Cambrian) in the center of the island under wet, humid conditions.

The Youseflo pluton, a part of Ahar - Arasbaran magmatic belt, is located in south east of Ahar city in north east of East Azarbayejan province of Iran. The pluton is mainly composed of quartz monzonite, granodiorite and granite, however, the major investigated rock is granodioritic in composition. Quartz, Plagioclase, biotite, amphibole, K-feldspar, chlorite, zircon, sphene, apatite and opaque minerals are the minerals of these rocks. Biotites, as a significant ferromagnesian mineral in Youseflo pluton, are Mg- rich, Cl-poor where all are primary types. Considering Fe/(Fe+Mg) (from 0.36 to 0.43) and Al IV (average 2.32 apfu), minerals are classified as biotite between Annite- siderophyllit endmembers. The study of mineral chemistry of biotites demonstrates that the calculated pressure based on total Al content in biotites varies from 0.19 to 0.89 kb which is indicative of a shallow emplacement depth. Crystallization temperature of biotites based on Ti content and Ti/Fe+2 ratio suggests an average temperature of 735 oC.

Andarian area is located north of Tabriz city, north west Iran, and tectonically is a part of Ahar-Arasbaran magmatic belt. Geology of the area includes Miocene shallow pluton, Cretaceous flysch-type sediments, metamorphic rocks )hornfels and skarn( and volcanic rocks. Mineralization occurred in two stages: primary and secondary. The primary ore minerals include Au, pyrite and stibnite. Malachite, azurite and iron-hydroxides are the main minerals of the secondary phase. Two phases of liquid-rich and gas-rich inclusions are the most common type of inclusions. The average formation temperature of quartz-gold vein deposit is 237°C with low salinity (with an average of 8.7 wt% NaCl equivalent). The pressure of entrapment for fluid inclusions is between 26 to 51 bars, which is equal to the depth of 270-550 m. Based on fluid inclusions studies, the gold bearing quartz veins formed in epithermal condition.

In the north of Ziaran village, a Sill olivine gabbro to monzodiorite composition is injected into the Karaj tuffs. The dominate minerals composition of plutonic rock are Plagioclase, Alkali feldspar, Pyroxene, Olivine and Biotite. Plagioclase composition is varies, and it’s changed from Labradorite to Bytownite. Alkali feldspar is in the Orthoclase range and Pyroxene is part of Diopside. Olivine composition change from Chrysolite to Hortonolite and most of the indicators are in the Hyalosiderite range. Biotite is one of the most prominent ferromagnesian mineral in the studied bodies. Compositionally, it is plotted between the field of annite and siderophylite. Most of these biotites are primary magmatic and some are plotted in the reequilibrated area. Based on the FeO*, MgO and Al2O3 binary and ternary diagrams, the studied biotites plot in the calc-alkaline orogenic field or crystallization temperature the have been calculated between 690º to 780 ºC. The chemical composition of the pyroxenes shows that these rocks have been crystallized in a subduction geological setting. The average crystallization temperature of clinopyroxenes is about 1215 °C. Furthermore, the calculated pressure for clinopyroxenes is less than 9 Kbars.

Delfard area is located in the northwestern of Jiroft, formed the northwestern part of the Jabālbārez granitoid complex, in Uromiyeh- Dokhtar magmatic belt. The Jabālbārez granitoid complex has a wide range of rocks inclusive from diorite to alkali granite, which were formed by magmatic differentiation process over the several course of consecutive pulses. Last pulses are masses of porphyry that showed evidence of copper mineralization. One of these intrusive bodies is Delfard. Copper mineralization in Delfard area​​ is more important than other parts of Jabālbārez. Consequently, in the area, three porphyry masses showing the evidence of porphyry copper mineralization. Chalcopyrite, Pyrite, Malachite, Azurite and Magnetite are indicative minerals. Alteration zones in Delfard area are silicic, potassic, arjelic, phyllic, and propylitic that can be correlated with Lovell and Gilbert model. According to studies, Delfard has high potential for exploration and drilling. The average copper content in the ore is about 1800 ppm. Petrogenesis review of the mafic rocks in Delfard area shows that these rocks originated from a richer source than NMORB. In addition, the rocks of Delfard area are Flux melting pointer that happened in the subduction of oceanic crust under the adjacent crust. In other words, the sequence of calc-alkaline rocks of Delfard area attributed to compressional tectonic regime that intrusived and erupted along the Uromiyeh- Dokhtar zone with development and high volume in the form of magmatic horizons. Finally, petrogenesis of studied granite series is similar to the calc-alkaline granitoids, which was originated from basaltic magma mantle metasomatised by fluids from the subducted slab. Based on zircon U-Pb geochronology,the age of Delfard granitoid is 15/83±1/3 Ma. One can imagine that, magmatic differentiation process was completed in a short time and intrusive body was sequentially penetrated and placed in the earth's crust in a short time.

A gabbro to monzonite sill is injected into the Karaj tuffs at the north of Parachan village, North of Karaj.. The main minerals of these rocks are plagioclase, pyroxene, K feldspar, olivine and biotite. Clinopyroxene mineral chemistry studies carried out on the intrusive bodies, indicate two types of diopside and augite clinopyroxene composition. The chemical composition of the pyroxenes shows that these rocks have been crystallized in a subduction geological setting. The average crystallization temperature of clinopyroxenes is about 1120 to 1170 °C, and it seems that clinopyroxenes crystallized at lower temperature than orthopyroxenes. Plagioclase composition in these rocks is variable, changing from andesine to labradorite. K feldspars are in the orthoclase range and olivine are hyalosiderite. Biotite is one of the most prominent ferromagnesian minerals in the studied bodies. Compositionally, it is plotted between the fields of annite and siderophyllite. Most of these biotites are primary magmatic and some are plotted in the re-equilibrated filed. Petrological evidence represent that fractional crystallization from gabbro to monzonite had main role in genesis of these rocks. Enrichment in LILE) Ba, Rb and Th(and also depletion in HFSE (Nb and Ti) in Rare Earth Elements distribution pattern in spider diagrams, indicate features of subduction-related rocks. Also they are enriched in LREE rather than HREE, the characteristic which is usually observed in the rocks from subduction environments and active continental margins. Chemical and petrological studies, indicate role of fractional crystallization in the evolution of magma, although, minor amounts of assimilation and contamination of magma by crustal rocks occurred. This alkaline magma has been formed by low degree of partial melting of an enriched sub-continental lithospheric garnet-lherzolite mantle source.

Dehaj-Meiduk area is located at North of Shahre-babak. There are nine porphyry intrusive bodies in this region, which include Meiduk, Parkam, Iejoo, Segino, Chah Firouzeh, Narkoh, Ayoub Ansar, Sara and Keder. Meiduk, Chah Firouzeh, Parkam, Iejoo and Segino are productive among them and Narkoh, Keder, Ayoub Ansar and Sara are barren. These intrusive bodies are mostly composed of porphyry diorite, quartzdiorite and granodiorite. Geochemical studies indicate that the magma of these rocks has the peraluminous to metaluminous nature and magma series are calc-alkaline with high potassium and shoshsonitic nature. The geochemical variation diagrams of major oxides and minor elements, illustrate the continuous spectrum of rock compositions for the studied samples, which indicates high crystallization differentiation during magmatic processes. Field observations, petrographic and geochemical studies suggest that the rocks in the Dehaj-Meiduk area are I type. All available data demonstrate that these rocks are result of subduction of Neotethyan oceanic crust beneath the central Iran continental crust. Flat subduction happened in some parts of the study area and because of that, partial melting rate has been low and as a result adakitic rocks are produced. The adakitic rocks have formed intrusive bodies in Pliocene. Since magma is depleted in metallic elements by forming earlier stage productive plutons, the later rocks do not contain metallic elements and are barren.