Petrological Journal

The geochemical and tectonic characteristics of the volcanic rocks in the east of Nahavand area (Sanandaj-Sirjan zone)

Samira Basiri; Somayeh Rahmani; Ahmad Ahmadi Khalaji; Zahra Tahmasbi

Volume 6, Issue 23 , October 2015, , Pages 1-26

Abstract

  The studied area is located in east of Nahavand which is a part of Sanandaj-Sirjan zone. The petrographic and geochemical investigations show that, these rocks consist of basalt, andesite-basalt, ...  Read More The studied area is located in east of Nahavand which is a part of Sanandaj-Sirjan zone. The petrographic and geochemical investigations show that, these rocks consist of basalt, andesite-basalt, andesite, trachy-andesite and dacite. Porphyritic, glomeroporphyritic, microlitic, hyalomicrolitic and comb textures are the common textures in the studied volcanic rocks. Two alteration zones including: argillitic and sericitic zones developed in this region. Alteration products are sericite, kaolinite, chlorite, hematite and calcite. Copper mineralization has occurred primarily in these rocks as filling voids and fractures. Malachite, covellite, magnetite, hematite and bornite are found within the veins. The geochemical data show that these rocks are related to calc-alkaline and shoshonitic magma series. Enrichment in LILE and LREE and depletion in HREE and HFSE with negative anomalies of Ti, Nb along with other evidences, such as high Th/Yb and their position on the tectonic discrimination diagrams indicate that the volcanic rocks in discussion were emplaced into the subduction zone related to an active continental margin setting. The Nahavand volcanic rocks lie in young and immature volcanic arcs or in the initial stages of volcanic arc formation. This situation is consistent with geological history of Sanandaj-Sirjan zone during the Jurassic to the Cretaceous ages.

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Petrology of gabbroic- dioritic intrusions in the Parishan Mountain (south of Qorveh), Kurdistan

Khadijeh Mohebbi; Ali Asghar Sepahi Gerow; Asharf Torkian

Volume 6, Issue 23 , October 2015, , Pages 27-44

Abstract

  The gabbroic intrusion of the Parishan Mountain in the south of Qorveh (Kurdistan province) is located between the villages of Zarrineh to Tekyeh-bala and based on structural divisions, ...  Read More The gabbroic intrusion of the Parishan Mountain in the south of Qorveh (Kurdistan province) is located between the villages of Zarrineh to Tekyeh-bala and based on structural divisions, it is a part of the Sanandaj-Sirjan zone. Based on petrographic features it consists of hornblende-pyroxene gabbro, gabbro, quartz-gabbro, dioritic gabbro, diorite and quartz-diorite rocks. Geochemical studies indicate that magma has metaluminous and calc-alkaline nature with medium potassium. Variation diagrams trends don’t confirm the continuous chemical between the samples. The negative correlation between the variations of SiO2 against oxides of Mg, Fe and Ca suggest fractional crystallization process for both of magmas. Tectonic setting discrimination diagrams indicate that magma depends to volcanic arc in active continental margin of related subduction zones. LREE enrichment in comparison to HREE and LILE enrichment and depletion of elements (i.e. Ti, Zr, Nb and Ta) can be due to crustal contamination and dependence of the body to subduction zones. The low Mg# value, high SiO2 contents, positive Yb and negative Ho anomalies suggest that mafic magma was originated from a metasomatized mantle, which it has melted lower crust. The linear and positive trends of incompatible elements against each other, suggests the role of fractionation crystallization in the mafic-intermediate magmas. Furthermore, field relationship and petrographic evidences show that mingling process of two magmas, including mafic and felsic magmas (intermediate), which are consistent with the tectonic setting of the studied area.

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Quaternary Syn-collision volcanism in north of the Sanandaj-Sirjan zone, magmatism within an active orogenic plateau

Monireh Kheirkhah

Volume 6, Issue 23 , October 2015, , Pages 45-64

Abstract

  The Quaternary volcanism from north of Sanandaj-Sirjan zone, in the west of Iran is a part of widespread series of the Quaternary syn-collisional magmatism in the Turkish- Iranian high ...  Read More The Quaternary volcanism from north of Sanandaj-Sirjan zone, in the west of Iran is a part of widespread series of the Quaternary syn-collisional magmatism in the Turkish- Iranian high plateau. This plateau is a part of the active Arabian-Eurasian collision zone. The basic lavas (basanites, hawaiites and alkali basalts) were erupted with main trend (NW-SE) of the Bitlis-Zagros Suture. Most of the basic lavas from the study area (Qorveh-Bijar region) show enrichment in the large ion lithophile elements (LILE, e.g., Rb, Ba, Sr) and light rare earth elements (LREE), the Takab basaltic rocks have lower LREE. The La/Nb ranging for all of the lavas is >1. Sr- Nd isotope ratios of these basalts reflect mantle source characteristics. The negative Nb anomaly and fractionation of LILE in these rocks may be depending on fractionation of minerals (Amphibole, Rutile) in the source. The geochemical characteristics suggest that, these rocks could be developed from small melting of thick Eurasia lithospheric mantle underneath the Turkish-Iranian plateau. The lithosphere delamination or slab break-off mechanisms in the study area with this thickness (~150-200 km) from metasomatised lithospheric mantle could not be the causes for partial melting of this mantle and finally ascent the magma in the study area. The generation of the Kurdistan lava is related to the melting of metasomatized mantle beneath this area which is an indication of subduction of Tethys underneath Eurasia prior to collision.

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Mineral chemistry and genesis determination of tourmalines from the granite-gneiss pluton in the northeast of Jan mine (Lorestan province(

Arezoo Moradi; Alireza Davoudian Dehkordi; Nahid Shabanian Boroujeni

Volume 6, Issue 23 , October 2015, , Pages 65-82

Abstract

  The outcrop of mylonitic granite-gneiss in the northwest of Azna city and the northeast of the Jan building stone mine is a part of Sanandaj-Sirjan zone. The tourmalines from these ...  Read More The outcrop of mylonitic granite-gneiss in the northwest of Azna city and the northeast of the Jan building stone mine is a part of Sanandaj-Sirjan zone. The tourmalines from these rocks are black and patchy or fine association. Based on EPMA data the tourmalines studied are shorl-dravite in composition with more tendency towards shorl. They belong to granitic environment and precipitated during hydrothermal condition. The chemical composition of the host granite is a major factor in distribution of elements in the studied tourmaline structural framework during the process of differentiation, as well as, faulting and uplifting of granitoid body. Some of the dominant substitution mechanisms in the structure of the investigated tourmalines are as follow: □X Al (Na R2+)-1, 21 xNa-1 zAl-1+xCa1 YR (OH)-1, Fe2+ Fe3+) (Mg Al)-1.

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Geochemistry of REEs and reconstruction of structural formula of Baba-Nazar garnet index, Takab, W.Azarbayedjan, Iran

Pariva Shirmohammadi; Yousef Rahim Souri; Samad Alipour

Volume 6, Issue 23 , October 2015, , Pages 83-96

Abstract

  The Baba-Nazar garnet deposit mineralized in hornfelsic body is located 80 km of NE of Takab town, Western- Azarbayedjan province. Ten samples from coarse-grained garnets of various ...  Read More The Baba-Nazar garnet deposit mineralized in hornfelsic body is located 80 km of NE of Takab town, Western- Azarbayedjan province. Ten samples from coarse-grained garnets of various colors were selected for major elements analysis by XRF and nine of these samples were analyzed for trace elements by ICP-OES. The presence of hornfels and carbonates in the contact with Doran granite intrusion indicates a skarn contact metamorphism garnet deposit in the area. Garnet crystals of 1-2 cm size are observed in anhedral to subhedral form of mainly deep green color. They show isotropic and high relief features in polarized light associated with abundant fractures. Major element analysis indicates that the Baba-Nazar Garnet consists of andradite-grossularite groups but in three samples the pyrope content is exceptionally higher than that of the grossular. The presence of grossular and andradite is revealed by XRD analysis. All the garnet minerals with different colors indicate enrichment of Zr, U, Y, Ti and V and depletion of Ba, Hf, Nb, Ta, Sc, Co and Th. REE's elements normalized to chondrites, in garnet with various colors garnet indicate enrichment of LREE's compared to HREE's and weak positive europium and positive cerium anomaly.

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The investigation of thermodynamic conditions in the formation of regional metamorphic rocks of the Tutak complex (southeast of Bavanat)

Behnaz Hosseini; Parham Ahmadi; Ahmadreza Ahmadi

Volume 6, Issue 22 , July 2015, , Pages 25-48

Abstract

  The Tutak metamorphic complex located in the southern part of the Sanandaj-Sirjan zone, is among the areas where the Paleozoic rocks are well exposed. This metamorphic complex mainly ...  Read More The Tutak metamorphic complex located in the southern part of the Sanandaj-Sirjan zone, is among the areas where the Paleozoic rocks are well exposed. This metamorphic complex mainly comprise of the Cambrian to the early Carboniferous marble, schist, amphibolite and genesis units. Garnet-biotite thermometric method and Garnet-biotite-muscovite barometric method carried out on dark schist from the Tutak metamorphic complex repersent 423 °C and 1.6 kb in the early stage of metamorphism to 708 °C and 5.9 kb during peak of metamorphism. These temperatures and pressures point to amphibolite facies conditions. The thermal cessation and also the marked difference in the degree of metamorphism between the Tutak complex and the late Carboniferous- early Permian succession in Surian, indicate that this phase of metamorphism probably occurred prior to the Late Carboniferous period.

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Reconstruction of deformation and metamorphism history in the Bultaq shear zone (Central part of Sanandaj-Sirjan zone)

Alireza Nadimi; Mortaza Sharifi; Iman Rahmani Moghaddam; Seyed Mohsen Tabatabaei manesh

Volume 6, Issue 22 , July 2015, , Pages 119-136

Abstract

  The Bultaq shear zone is located 185 km north-west of Isfahan. The study area is a part of the Sanandaj–Sirjan zone, which is affected by ductile and brittle–ductile deformation ...  Read More The Bultaq shear zone is located 185 km north-west of Isfahan. The study area is a part of the Sanandaj–Sirjan zone, which is affected by ductile and brittle–ductile deformation and consists of slate, schist(garnet-muscovite schist, enriched quartz-muscovite schist and biotite-muscovite schist), amphibolite marble, metavolcanic, andesite and tuff. There are several duplex structures and thrusts with NW-SE-trend and NE dip in the Bultaq shear zone. This shear zone is parallel to the Zagros Organic thrust. Also, boudinage structures geometric analysis, mesoscopic scale asymmetric folds, microscopic studies of S-C, S-Ć cleavages and σ- type porphyroclast confirmed right-lateral strike-slip movement. These fabrics show right rounded cuts in region in some parts. Mylonitic foliations were used to calculate elongation (e) and stretch (s) in this area. The microstructures were formed under green schist to amphibolite facies conditions. The metamorphic rocks have been formed in a Barrovian metamorphism type (medium temperature - pressure) and affected by three metamorphic and deformation phases. The metamorphic phases include dynamothermal, dynamic and retrograde and the deformation phases are D1, D2 and D3.

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Petrology, geochemistry and mineral chemistry of the subvolcanic rocks and enclaves in the Shirmazdtapeh area (SW Arak)

Mansoureh Miresmaeili; Zahra Tahmasbi; Ahmad Ahmadi Khalaji; Farzaneh Sepahvand

Volume 6, Issue 22 , July 2015, , Pages 137-156

Abstract

  The sub volcanic rocks in Shazand area (the Markazi province) which formed a part of the Sanandaj-Sirjan zone are composed of dacitic rocks with major minerals such as plagioclase, ...  Read More The sub volcanic rocks in Shazand area (the Markazi province) which formed a part of the Sanandaj-Sirjan zone are composed of dacitic rocks with major minerals such as plagioclase, quartz, alkali feldspar and minor minerals such as biotite, zircon and apatite. One of the characteristic features of these rocks is the existence of two types of enclaves with dacitic and andesitic compositions. The former, share similar mineralogical composition with the host dacitic rocks and the latter is characterized by the presence of amphibole phenocryst (pargasite), orthopyroxene (enstatite) and plagioclases (labrador-bytownite). Thermometry on biotite and feldspar from the host dacite rocks showed temperature range of 675 and 600 ºC, respectively. The calculated temperature formation for biotite, feldspar and pargasite from the andesitic enclaves are 620, 650 and 810 ºC, respectively. LREE enrichment in comparison with HREE, high LILE relative to HFSE, negative anomalies of Nb, Ti, P, and positive anomalies of Pb, K indicate that these rocks formed in subduction zones. Also, the geochemical characteristics of these rocks reveal that the nature of magma is calc-alkaline enriched in potassium derived from partial melting of continental crust units related to normal active continental margin volcanic arc.

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Mineral chemistry of the granitoid Ghalilan body (SW-Qorveh, Kurdistan) and its estimates of physicochemical parameters

Ashraf Torkian

Volume 5, Issue 20 , January 2015, , Pages 35-52

Abstract

  The Ghalilan granitoid pluton is located in SW- of Qorveh and in the Sanandaj-Sirjan zone. Based on petrographic studies, the body includes three rock units, composing of granitoid, ...  Read More The Ghalilan granitoid pluton is located in SW- of Qorveh and in the Sanandaj-Sirjan zone. Based on petrographic studies, the body includes three rock units, composing of granitoid, porphyritic granite and diorite. These rocks are mainly composed of plagioclase, alkali-feldspar, quartz and amphibole. The composition of the studied plagioclase is An 14-50 (the minimum value in granite) to An 41.4-58 (the maximum value in diorite) and some samples display normal zoning and rapakivi texture. The results of electron microprobe analysis (EMPA) indicate the amphiboles studied are magnesio hornblende in composition implying I-type nature of magma. Application of different barometers and thermometers (e.g. Al-in-Hornblende, Plagioclase-Amphibole) exhibits a pressure of ~ 1 to 3.3 kbar and temperatures of 690-804°C for the intrusion. The reaction of these variations is reflected by the growth of minerals such as large zoned plagioclase crystals in the porphyrtic granites. In addition, the presence of the zoned plagioclase implies the PH2O variations at the time of crystallization and emplacement of the magma in the depth of ~8 km. The composition of hornblendes suggests their formation in high oxygen fugacity condition, which is in accordance with their mineralogical characteristics and tectonic setting of Ghalilan body (subduction in active continental margin).

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Serpentinization of the Piranshahr peridotites: investigations on serpentine polymorphs and metamorphic evolutions of the metaperidotites

Mohsen Moazzen; Farzaneh Valinasab Zarnagh; Robab Hajialioghli

Volume 5, Issue 20 , January 2015, , Pages 71-90

Abstract

  The study area is located in NW of Piranshahr town, Western Azerbaijan province. Based on the petrography, mineralogy and textural relations, the peridotites studied are classified ...  Read More The study area is located in NW of Piranshahr town, Western Azerbaijan province. Based on the petrography, mineralogy and textural relations, the peridotites studied are classified into two groups: serpentinized peridotites and serpentinites. The second type, on the base of serpentine polymorphs and texture can be classified into three subgroups in turn: a) hydrated serpentinites which are characterized by low temperature serpentine polymorphs (chrysotile and lizardite), b) antigorite (high temperature serpentine polymorph) bearing serpentinites which formed at relatively high T and P conditions having interpenetrative texture and c) listwanitic serpentinites with brecciated texture containing of minerals as serpentine, chlorite and high amounts of carbonates. Distinguishing of serpentine polymorphs in the investigated rocks has been done using Raman spectroscopy and microprobe analysis. Formation of low-T serpentine polymorphs in the hydrated serpentinites are most likely related to the in-situ alteration of oceanic crust whereas antigorite in the metamorphic serpentinites is formed due to regional metamorphism during subduction and/or subsequent closure of ocean. Tremolite, clinochlore/picnochlore and Fe-rich spinel are coexisting minerals with antigorite. Temperature and pressure of the antigorite bearing serpentinites are obtained on the basis of equilibria reactions using THERMOCALC, as 550ºC and 7 kbar, respectively. On the base of olivine and pyroxene norm, the protolith composition of the Piranshahr metaperidotites is determined as harzburgite and less lherzolite. The high MgO and relatively low CaO and Al2O3 contents of the investigated rocks indicate ophiolitic characteristics of the Piranshahr metaperidotites. Considering the location of the Piranshahr ophiolites at the end of the northwestern part of the Zagros ophiolitic belt, it can be concluded that hydrated serpentinites and antigorite-bearing serpentinites are formed in relation with static oceanic floor alteration and subsequent dynamic metamorphism during subduction and/or closure of the Neotethys ocean, respectively.

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The study of parental rock of post Jurassic dolerites of volcano-sedimentary belt in north of Shahrekord

Sayyed Naeim Emami; Zahra Eliasi

Volume 5, Issue 19 , December 2014, , Pages 21-36

Abstract

  Subvolcanic basic rocks have been exposed in the north of Shahrekord, as a part of Sanandaj-Sirjan structural zone in the form of stocks and dykes in post Jurassic to early Cretaceous ...  Read More Subvolcanic basic rocks have been exposed in the north of Shahrekord, as a part of Sanandaj-Sirjan structural zone in the form of stocks and dykes in post Jurassic to early Cretaceous owing to their intrusion and emplacement into upper Jurassic volcano-sedimentary suite. These rocks are dolerites and show subvolcanic particular textures such as intergranular, intersertal and ophitic. The main constituent minerals of dolerites are plagioclase (Labradorite) which has altered to albite due to spilitization and clinopyroxene including augite and diopside. Secondary minerals are chlorite, calcite, epidote, clinozoisite and some minor minerals such as apatite, magnetite, titanomagnetite, ilmenite and sphene. Dolerites, based on geochemical and mineralogical signitures, are classified into the two distinct groups. The first group with tholeiitic affinity originated from an upper lherzolith source rock in a post subduction tension environment. The second group with alkaline and transitional nature generated from an eclogite source rock in an oceanic intraplate basalts environment. Dolerites have been formed after upper Jurassic or early Cretaceous due to their intrusion and translocation in the upper Jurassic volcano-sedimentary rocks.

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The study of petrography, geochemistry and petrogenesis of the basaltic rocks, NE-Qorveh (Kurdistan)

Nafiseh Salehi; Ashraf Torkian

Volume 5, Issue 19 , December 2014, , Pages 37-52

Abstract

  In the northeastern part of Kurdistan province, there are many volcanic cones that are basaltic in composition. Petrographic investigations reveal these rocks are dominated by clinopyroxene ...  Read More In the northeastern part of Kurdistan province, there are many volcanic cones that are basaltic in composition. Petrographic investigations reveal these rocks are dominated by clinopyroxene and olivine phenocrysts and plagioclase and pyroxene micro crystals, while space between them is filled by opaque mineral and brown glass. The presence of zoned pyroxenes and sieve texture in these rocks are evidences of crustal contamination and magmatic unequilibrium. The studied rocks with 5-14% normative nepheline are alkaline nature. On Harker diagrams fractional crystallization is indicated by MgO decreasing while CaO, FeO, Ni, TiO2 and Cr and SiO2 increase. On discriminated diagrams the tectonic environment of the samples is inter continental extensional zone. Geochemical characteristics such as LILE, LREE enrichment, Nb, Ta and Y negative anomalies, positive anomalies of Ba, Pb, Th and Th/Yb enrichment suggest that the basaltic lavas studied derived from lithospheric mantle that contaminated by subduction fluids. Also, Zr/Hf and Hf/La ratios are evidence for upper crustal contamination. High (Th/Yb)N, (La/Yb)N and high Nb anomaly (0.37-0.98) show that the magma generated from a garnet lherzolitic source.

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The study of petrogenesis, mineral chemistry and thermobarometry of contact metamorphic rocks from aureole of Alvand body, Hamedan

Nasrin Asadi; Ali Asghar Sepahi Gerow; Sedigheh Salami

Volume 5, Issue 19 , December 2014, , Pages 67-86

Abstract

  There are various contact and regional metamorphic rocks, from low to high grade in contact of the Alvand plutonic body. These rocks have undergone regional dynamothermal metamorphism ...  Read More There are various contact and regional metamorphic rocks, from low to high grade in contact of the Alvand plutonic body. These rocks have undergone regional dynamothermal metamorphism and in the later stage due to heat and fluids derived from the body have been subjected to contact metamorphism. Hornfelses from the east and the north-eastern part of the Alvand aureole have sedimentary protolith of shale type. In the studied hornfelses, garnets are almandine-rich composition of biotite is sidrophyllite and of the plagioclase varies from albite to andesine. Based on thermometric cation-exchange method of garnet-biotite pair, using different calibrations, the obtained temperature for cordierite-free hornfels, is about 580 °C and for the cordierite-bearing hornfels 566 °C. In barometry with GPBQ system, calculated pressure for hornfelses is strongly consistent with pressure obtained from multiple equilibrium curves for these rocks and was estimated to be about 2.9 to 3.6 Kbar. The obtained temperature and pressure using composition from rim of minerals in cordierite- and aluminosilicate-bearing rocks, with multiple equilibrium curves and THERMOCALC software represent temperature of about 650 °C and pressure of 3 Kbar.

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Mineral chemistry, magmatic series and geotectonic setting of Ghaidou monzogranite southeast of Khomein (Sanandaj-Sirjan zone)

Akram Sadat Mirlohi; Seyed Mohsen Tabatabaei manesh; Gloria Kargaran; Mortaza Sharifi

Volume 5, Issue 19 , December 2014, , Pages 87-106

Abstract

  The Ghaidou monzogranite in the southeast of Khomein constitute a part of rock complex from the northern part of the Sanandaj-Sirjan zone. This body intruded into the Jurassic micaschists ...  Read More The Ghaidou monzogranite in the southeast of Khomein constitute a part of rock complex from the northern part of the Sanandaj-Sirjan zone. This body intruded into the Jurassic micaschists and created a metamorphic aureole. Also, aplitic veins, tourmaline bearing pegmatitic dikes, felsic microgranular enclaves and surmicaeous enclaves are observed in this area. The predominant minerals of these rocks are K-feldspar (orthoclase and microcline), Na-plagioclase (Albite- oligoclase in the monzogranite and oligoclase in the felsic microgranular enclaves), quartz and black mica (Annite) -as the main minerals- with minor amount of tourmaline (schorle), garnet, white mica (phengite), sillimanite, kyanite, zircon, apatite and ilmenite. On the basis of biotites mineral chemistry, these phases are enriched in FeO and Al2O3 and relatively low in TiO2. These minerals are magmatic and primary and thermometry results yielded 660-690 ºC. According to the chemical composition of primary igneous biotites in the enclaves and monzogranites, these rocks have calc-alkaline, peraluminous and an orogenic continental collision affinity characteristics of S-type granites. Also, the biotite composition and the presence of ilmenite point to low oxygen fugacity and redox conditions during magma crystallization. Based on the available data, the generation of these rocks can be related to Arabian-Eurasia collision zone.

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Volcanic and subvolcanic rocks dating in the north of Shahrekord by 40Ar/39Ar method, a new approach regarding the occurrence andduration of the Jurassic volcanism in the Sanandaj-Sirjan zone

Sayed Naeim Emami; Mahmoud Khalili

Volume 5, Issue 18 , November 2014, , Pages 1-14

Abstract

  The volcano - sedimentary complex in the north of Shahrekord as a belt with NW-SW trendand 396 km2 area is parallel to the Zagros structural zone within the central part of the Sanandaj- ...  Read More The volcano - sedimentary complex in the north of Shahrekord as a belt with NW-SW trendand 396 km2 area is parallel to the Zagros structural zone within the central part of the Sanandaj- Sirjan Zone. The volcanic rocks have mafic and intermediate affinity. The subvolcanic microdiorite rocks were exposed as small stocks. The pyroclastic rocks are composed of tuffs, lapilli tuffs, agglomerates, volcanic breccias and tuffites. To determine the age of the aforementioned volcanic rocks, due to the presence of fresh amphibole crystals in the andesitic and microdioritic rocks, 40Ar/39Ar dating method was applied. On the base of 40Ar/39Ar data, the studied volcanic and subvolcanic rocks have formed between 145 to 169 Ma corresponding to Callovian to Titonian stages (upper Dogger to upper Malm of Jurassic period). The dating results are well consistent with the other geochronological studies performed on some of the intrusive bodies in the Sanandaj-Sirjan Zone (i.e. Aligoodarz and Alvand intrusives) which are related to the subduction of Neothetyan Oceanic Lithosphere below the Central Iran Plate. Nevertheless, the aforesaid volcanism, belonging to middle Kimmerian orogenic phases in this part of the Sanandaj-Sirjan Zone, is reported for the first time.

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Investigation on protolith and tectonic setting of metamorphic rocks in the Surian complex using petrographic and geochemical data

Mohammad Ali Rajbzadeh; Soheila Esmaeili

Volume 5, Issue 18 , November 2014, , Pages 49-62

Abstract

  The metamorphic rocks of the Surian complex occurred along the Bavanat Valley, northeast of Fars province at the eastern edge of the Sanandaj-Sirjan zone. The complex is located between ...  Read More The metamorphic rocks of the Surian complex occurred along the Bavanat Valley, northeast of Fars province at the eastern edge of the Sanandaj-Sirjan zone. The complex is located between the Surian fault in the northeast, and Jian fault in the southeast, and consists of chlorite epidote schist, chlorite actinolite schist, quartz chlorite schist, mica schist and andalusite muscovite schist. Geochemical data (Al2O3, CaO, MgO, Ni, P2O5, TiO2 and REE) contents reveal that the primary rocks of andalusite muscovite schist, quartz chlorite schist and mica schist were formed in sedimentary environments, whereas those of the chlorite actinolite schist and chlorite epidote schist have igneous origin. The concentrations of major immobile elements (e.g. Al, Ti), REE and Highs Field Strength Elements (HFSE) (e.g. Nb, Y, Zr), indicate that the rocks of sedimentary origin were formed in active continental margin setting in association with turbidites of deep sea floor and those of igneous origin show tholeiitic basalt nature of rift basins.

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Petrography, mineral chemistry and geochemistry of granitoids of the Samen plutonic complex (SW Malayer, Hamedan)

Ahmad Ahmadi Khalaji; Farahnaz Sepahvand; Ali Asghar Sepahi Gerow; Sedigheh Salami

Volume 5, Issue 18 , November 2014, , Pages 77-92

Abstract

  The Malayer plutonic complex is located in the northern Sanandaj-Sirjan zone of the western Iran. An intrusive body with granodioritic component known as the Samen granodiorite is in ...  Read More The Malayer plutonic complex is located in the northern Sanandaj-Sirjan zone of the western Iran. An intrusive body with granodioritic component known as the Samen granodiorite is in the center of this complex, which is accompanied by other granitic rocks and small mafic bodies. The major part of this intrusive body composed of tonalitic-granodioritic rocks. The monzogranitic rocks, unlike the other plutonic complexes of the Sanandaj-Sirjan zone such as the Alvand pluton constitute a small part of this complex, and probably formed and emplaced after tonalite-granodiorite body. In terms of geochemical characteristics these rocks are calc-alkaline, peraluminous and S-type, while tonalitic-granodioritic rocks are metaluminous and I-type in nature. These granitoids on the spider diagrams show enrichment in LILE (K, Rb and Th) and depletion in HFSE (Nb, P and Ti). Also they are enriched in LREE rather than HREE, the characteristics which are usually observed in the rocks from subduction environments and active continental margins. The biotites in the granodiorites are siderophyllite, amphiboles and plagioclases are hornblende and andesine type. Barometric calculations yield pressures of 1-1.2 kbar (equal to 3-4 km of depth) for intrusive rocks. Crystallization temperature of the granodioritic rocks in 1Kbar pressure is estimated to be 592.2 to 756.9 °C and in 1.2 Kbar pressure around 591.2 to 757.6 °C.

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Petrology of the Molataleb village granitoid (North of Aligudarz), NW of Isfahan, low temperature peraluminous I-type

Mahin Mansouri Esfahani; Mahmoud Khalili

Volume 5, Issue 17 , April 2014, , Pages 119-136

Abstract

  The Molataleb granitoid lies in the Sanandaj-Sirjan Zone and composed of granodiorites, tonalites and minor diorites which intruded into the Jurassic (Lias-Dogger) shales and slates. ...  Read More The Molataleb granitoid lies in the Sanandaj-Sirjan Zone and composed of granodiorites, tonalites and minor diorites which intruded into the Jurassic (Lias-Dogger) shales and slates. Quartz, plagioclase, orthoclase, biotite, amphibole, tourmaline, andalusite, garnet, apatite and zircon are the major and minor minerals of these rocks. The essential petrological characteristics of the body are, the P2O5 content decreases versus the SiO2 wt% increases, the content of aluminium saturation index (ASI= 1-1.1), the trend of increasing of Zr vs SiO2, the chemistry of biotites and the formation temperature of the body (500-700°C), all are the remarkable features of low temperature medium peraluminous I-type granites. The descending trend of Al2O3, TiO2, Eu and Zr against Larsen Index and also the decrease of K/Rb ratio versus Rb suggest fractional crystallization of plagioclase in the studied granitoid samples. The chondrite-normalized REE's diagrams display LREE's enrichment relative to HREE's. This can be owing to low degree partial melting or relatively enrichment of alkali elements in the source rocks associated with subduction zone. The alkali elements enrichment may be due to crustal contamination. Also, the high level of LILE's and the HFSE's depletion indicates that magmatism occurred in subduction of Neotethyan oceanic crust beneath Central Iranian microplate and the studied intrusive body is classified as volcanic arc granite (VAG).

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The investigation of anisotropy of magnetic susceptibility (AMS) and the emplacement mechanism of Darreh Bagh granitoid pluton (NW Aligudarz)

Mahmoud Sadeghian; Sakineh Shekari

Volume 4, Issue 15 , March 2014, , Pages 55-76

Abstract

  The Darreh Bagh granitoid pluton (DGP), with middle Jurassic age (178 Ma), located in the northwest of Aligudarz city. The pluton is mainly granodioritic composition which emplaced ...  Read More The Darreh Bagh granitoid pluton (DGP), with middle Jurassic age (178 Ma), located in the northwest of Aligudarz city. The pluton is mainly granodioritic composition which emplaced in metapelitic rocks of Sanandaj-Sirjan structural zone. For the first time, the emplacement mechanism of this pluton, investigated by anisotropy of magnetic susceptibility (AMS) method. Based on the present investigations, the mean magnetic susceptibility, in terms of µSI for the studied rock groups are as follow: granodiorites (257), leucogranites (47), high tourmaline leucogranites (148), low tourmaline leucogranites (48), migmatites (437), surmicaceous enclaves (386). Considering the obtained values, the felsic part of the DGP belongs to the paramagnetic granitoids (500>km>0 in µSI) (equal to ilmenite series or S-type). Based on the magnetic parameters and their interpretations it is possible to divide DGP into the A and B domains and A1, A2 subdomains. The magnetic lineations in the subdomains oriented to the north. Whereas in the middle part of the pluton (B domain) it oriented dominantly to the east and southeast. Based on distribution patterns of magnetic lineations these domains were emplaced with a short delay compared to each other. Meanwhile, A domain was emplaced prior to B domain. With attention to distribution patterns of magnetic lineations and foliations, the principles of interpretation of magnetic parameters and regional geological characteristics, the Darreh Bagh granitoid pluton was emplaced in the form of a relatively large sill in a dextral shear zone (related to a transpression regime).

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Petrography, Mineralogy and Mineralchemistry of Ochestan contact metamorphic rocks (South of Mahallat)

Mohsen Tabatabaei Manesh; Zari Eslami; Mortaza Sharifi

Volume 4, Issue 16 , February 2014, , Pages 73-86

Abstract

  The skarns of the Ochestan area are located in the Sanandaj- Sirjan zone, about 60 Km south of Mahallat. The rock complex in this area consist of intrusive bodies and metamorphic rock ...  Read More The skarns of the Ochestan area are located in the Sanandaj- Sirjan zone, about 60 Km south of Mahallat. The rock complex in this area consist of intrusive bodies and metamorphic rock such as: schist, phyllite, slate, hornfels, amphibolite and metavolcanic. The injection of magma in the Cretaceous-Paleocene with syenogranite and monzogranite composition into the Paleozoic limestone and dolomite led to formation of skarn and marble. Clinopyroxene (diopside), olivine (forsterite), tremolite, talc, serpentine, phlogopite, margarite, wollastonite, opaque minerals, calcite and quartz are observed minerals in contact metamorphism rocks. According to the mineralogical studies, the Ochestan skarns are exoskarn-type and the presence of minerals such as: forsterite, diopside, tremolite, antigorite and phlogopite show that the host rock is dolomitic the in study area. These skarns show zoning of intrusive body into the host rock: wollastonite skarn, pyroxene skarn, forsterite- serpentine marbles, mica marbles, tremolite- talc marbles, calcite and dolomite marbles.

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Geochemistry, petrology and U-Pb geochronology of Ghazan mafic-ultramafic intrusion, NW Iran

Manijeh Asadpour; Seyed Mohammad Pourmoafi; Soraya Heuss

Volume 4, Issue 14 , July 2013, , Pages 1-16

Abstract

  Ghazan mafic-ultramafic intrusive is a small igneous body at the extremity of NW of Sanandaj-Sirjan zone in the NW of Iran, intruded into the early Paleozoic sedimentary rocks. This ...  Read More Ghazan mafic-ultramafic intrusive is a small igneous body at the extremity of NW of Sanandaj-Sirjan zone in the NW of Iran, intruded into the early Paleozoic sedimentary rocks. This body includes non-mineralized mafic and mineralized ultramafic part (containing Fe-Ti oxides). The mafic rocks are composed mainly of pegmatite gabbro to micro gabbro, metagabbro and anorthosite, with a simple mineral assemblage (plagioclase, clinopyroxene, orthopyroxene, ilmenite). The ultramafic rocks include pyroxenite and wherlite (with high proportion of ilmenite and titanomagnetite) in accompany by large to small blocks of pure Fe-Ti oxide are widespread in the area . The ultramafic part is located within the intrusion and enclosed by mafic rocks. Based on the results of chemical analyses, the primary magma of mafic-ultramafic rocks, derived from a mantle source. During magma ascent the composition of magma has been changed from alkaline to sub-alkaline. U-Pb dating, of a primary and magmatic zircon, gives an age of 299 Ma and dating on metamorphic and inherited zircons shows maximum age of 541 Ma. The younger age represents the the Upper Paleozoic plutonism in the northern part of the Sanandaj-Sirjan zone. The older ages related to the Precambrian basement rocks or older basement rocks on the way of magma, which are incorporated in the magma as exnocryst. The greenschist facies metamorphism, high-temperature deformation as well as altered rocks are widely observed in the area.

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Geochemistry of Ghareh Boltagh granitoid body, Buin-Miandasht (SE of Aligudarz)

Nahid Shabanian Boroujeni; Alireza Davoudian Dehkordi; Fatemeh Panahdar

Volume 3, Issue 11 , December 2012, , Pages 59-76

Abstract

  The Ghareh Boltagh granitic pluton, as a part of the magmatic-metamorphic complex of the north of Boein Miandasht, exposed in the southeastern of Aligoodarz and located in Sanandaj-Sirjan ...  Read More The Ghareh Boltagh granitic pluton, as a part of the magmatic-metamorphic complex of the north of Boein Miandasht, exposed in the southeastern of Aligoodarz and located in Sanandaj-Sirjan zone. The complex consists of granite, diorite and gabbro with metabasite rocks. Mineralogically, the granitic rocks are mainly composed of major minerals of quartz, alkali feldspar, plagioclase, and minor minerals of biotite, amphibole, epidote, zircon, sphene, apatite, tourmaline, allanite and opaque. The Ghareh Boltagh granitic pluton consists of high SiO2 (68.74-72.59 wt. %), K2O (4.5-5.01 wt. %) and Na2O (3.75-4.23 wt. %), and Fe2O3tot (2.2-3.78 wt. %). It shows metaluminous to slightly peraluminous nature. On the base of chondrite-normalized REE diagram, all of the samples invariably show a relatively enrichment in LREES rather than HREES with negative Eu anomalies. Their primitive-mantle normalized spider diagrams display negative Ba, Sr, P and Ti anomalies. The calculated zirconium saturation temperatures range from 799 to 848 °C. The studied rocks, geochemically, belong to the A2-type granites, generated in a post-collisional tectonic setting.

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Petrology of the Tekyeh-Bala area granite veins (northeast of Sonqor), some evidences for A2-type granitoids

Farhad Aliani; Mohammad Maanijou; Mirmohammad Miri

Volume 3, Issue 9 , June 2012, , Pages 1-16

Abstract

  Magmatic activities during Mesozoic and Cenozoic emplaced several basic, intermediate and acidic intrusive bodies in the north part of the Sanandaj-Sirjan zone. Most of these bodies ...  Read More Magmatic activities during Mesozoic and Cenozoic emplaced several basic, intermediate and acidic intrusive bodies in the north part of the Sanandaj-Sirjan zone. Most of these bodies have genetic relationship with each other, but some of them formed by special magmatic processes and show different geochemical features. In the Tekyeh-Bala area (northeast of Sonqor) there are several granite veins which penetrated into the diorite rocks and have different geochemical characteristics from the host diorite. These granitic veins are alkalic belonging to the shoshonitic magma series. Also, they possess the geochemical properties of A-type granitiods, i.e., metaluminous nature (A/CNK=0.96-0.99), high HFSE (HFSE=192-412 ppm), Zr (230-420 ppm), FeOt/(FeOt+MgO) (0.89 in average) and K2O (4.2-6.2 wt%) contents. Regarding to the relatively enrichment of Rb, K, Cs and Th with respect to Nb and Ti in these samples which is a indicator property of active continental margins and also their post-orogenic tectonic regime, the studied granite can be classified as A2-type granitiods.

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Petrology and mineral chemistry of Ochestan granitoids (south of Mahallat, Markazi province)

Seyed Mohsen Tabatabaiemanesh; Akram sadat Mirlohi; Mehri Movahedi

Volume 2, Issue 7 , June 2011, , Pages 51-74

Abstract

  The Ochestan granitoids are located 60 Km South of Mahallat in Markazi province and in Sanandaj-Sirjan zone. Based on petrographic studies, these rocks are alkali feldspar-granite, ...  Read More The Ochestan granitoids are located 60 Km South of Mahallat in Markazi province and in Sanandaj-Sirjan zone. Based on petrographic studies, these rocks are alkali feldspar-granite, granite (syenogranite and monzogranite) and granodiorite. Alkali feldspar (orthoclase and microcline), plagioclase (albite and oligoclase), quartz and muscovite are present as the major minerals and tourmaline, biotite, zircon, garnet, apatite, opaque minerals, rutile and chlorite as the secondary ones. Foliation is found in many parts of the pluton indicating mylonitization process. Geochemical studies show sub-alkaline (calc-alkaline), peraluminous and S-Type for the granitoid studied. According to spider diagrams, upper crust is considered as the magma source, and syncollision as the geotectonic setting. Partial melting of metapelites can be assumed as a source of magma generation in regard to the type of granitoids, geochemical data and metamorphic rocks exposing in this area.

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Petrogenetic variations of the Jurassic magmatic sequences of Hoseinabad-Hajiabad regions in Sanandaj-Sirjan Zone (south of Iran)

Iman Monsef; Mohammad Rahgoshay; Hubert Whitechurch

Volume 1, Issue 4 , March 2011, , Pages 89-112

Abstract

  The Jurassic magmatic sequences in the southern part of Sanandaj-Sirjan Zone show significant geochemical variations during their compositional evolution. These magmatic sequences have ...  Read More The Jurassic magmatic sequences in the southern part of Sanandaj-Sirjan Zone show significant geochemical variations during their compositional evolution. These magmatic sequences have exposed in the Hoseinabad region with Early to Middle Jurassic age and in Hajiabad region with Late Jurassic to Early Cretaceous age. The parent magma of the first sequence in Hoseinabad region, with island arc tholeiite (IAT) affinity have been originated from the spinel lherzolite mantle source with primitive mantle (PM) composition. This mantle source is affected by liquids and sediments resulted from the subducting slab. The parent magma of the second sequence in Hajiabad region with island arc tholeiite to transitional affinity have been resulted from the garnet - spinel lherzolite mantle source with E-MORB composition. These compositional changes may be related to high sediment and hydrothermal fluxes which resulted from the deep subducted slab into the mantle wedge. These magmatic sequences are originated during the subduction of the Neo-Tethyan oceanic lithosphere under the Sanandaj-Sirjan Zone, during the Early Jurassic to Early Cretaceous time, in the island arc tectonic environment.

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