Showing 8 results for Qorveh
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Volume 20, Issue 2 (6-2012)
Abstract
The study area is located in the southern part of Qorveh granitoid complex. Investigation of textural and mineral chemistry evidence in granitoid host with composition of granodiorite, granite, qtz-monzonite, and mafic microgranular enclave (MME) with composition of qtz-diorite to meladiorite, are focused in this paper. Microscopic study and data of microprobe analyses in host and enclave rocks reveal disequilibrium textures and compositional (such as, tabular plagioclase with inclusions, sieved, zoned and resorbed plagioclases, needles of apatite, overgrowth of felspars and zoned amphiboles) in the granitoid host and mafic microgranular enclave. Because of agreement between the textural and mineralogical evidence, we accept the Elburg theory that globules (drops) of mafic magma and host granitoid rock have mixed and effective process in formation of enclave is a simple mechanical magma mixing (magma mingling), ceased by mafic magma stopping in a felsic magma chamber. This fact is linked to geochemical conditions and tectonic setting of the complex in Sanandaj-Sirjan Zone, as a remained zone of subduction setting.
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Volume 21, Issue 3 (10-2013)
Abstract
The studied shear zone is located in E-Qorveh (Kurdistan). The rocks of this zone are granite and granodiorite in composition. In present paper, deformed rocks, protomylonites and mylonites, are investigated in Sangin-Abad, Koh-e-Gazgaz and Poloserkan areas. Petrographic studies show that evidence of tectonic activities are such as myrmekite, recrystallized and slide alkali feldspars, fractured plagioclases, dynamic quartzes, perthitic orthoclase, feldspar crystals with enriched rim from alkalis (mantled texture) with Or 91.19 - 91.54. Comparing geochemical data of whole-rocks and primary rock (protolith) reveal that there are varieties in abundances of main elements such as increasing of CaO، MnO، TiO2 & P2O5 in protomylointes and mylonites. Also, quartz-rich veins and plagioclases altered have observed in the zone. These examples are interpreted to present activities of hydrothermal fluids and open system. The Feldspars are sodic-potsic and sodic in composition in Sangin-Abad & Koh-e-Gazgaz, and Poloserkan. Overall, relationship field, microstructural, textural, geochemical and mineral chemistry characteristics confirm role of the shear zone for formation of these features. Many of researchers have approved relationship between forming of microstructures with stress/ strain and hydrothermal fluids. The studied biotite crystals with content of (∑FeO + MnO ≈ 13.4-42.21) are neoform. They may be occurred by post-magmatic fluids of the Qorveh granitoid batholith. Formation temperature of biotites is ~550 to ~750 ºC which corresponds to this deformation temperature.
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Volume 22, Issue 2 (7-2014)
Abstract
The study area is located in west of Iran (38 km SW of Qorveh). This region is part of Sanandaj-Sirjan zone. This area contains several pegmatitic dikes and based on mineralogical and geochemical characteristics belong to muscovite-rare-element pegmatites. The lithology of this body varies from pegmatitic syenogranite to granodiorite. Various rock bodies in this suite are mostly I-type and calc-alkaline, with moderate to high K and regarding to the aluminum saturation degree they are subaluminous to peraluminous. The low (La/Yb) N ratio in the pegmatitic samples (2.28) indicates progression of fractional crystallization in the initial magma. The low Eu/Eu* ratio (0.137) in these pegmatites indicates differentiation of calcic plagioclase before pegmatitic stage. In the spider diagrams, LILE elements such as K, Rb and Th are enriched relative to HFSE elements specially Nb and Ti. Intrusion of this pegmatite in the carbonate rocks led to skarn development. These skarns have different minerals such as tremolite, epidote, scapolite, clinozoisite, pyrrhotite, pyrite, chalcopyrite and magnetite. Based on geochemical characteristics of these pegmatites, their composition, in accordance with bodies, is related to Sn, W and Mo skarns. This fact is in agreement with the studies in area regarding Sn & W mineralization.
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Volume 22, Issue 4 (1-2015)
Abstract
The Plio- Quaternary volcanoes are located in the NE-Qorveh (Kurdistan) in the Qorveh-Takab volcanic belt, in the Hamedan-Tabriz Zone (HTZ). The volcanic rocks consist of basalt to olivine-basalt. The electron microprobe (EMP) analyses of pyroxenes show occurrence of one type of clinopyroxene, as diopside (Fs 2.65-6.42 En 40.44-50.47 Wo45.97-53.14) with Mg # = 84-98. The compositions of the pyroxenes suggest that rocks belong to alkaline-subalkaline magmatic series. Considering different methods of geothermometry of clinopyroxene, the temperature of crystallization stage for pyroxene was 800-1300°C. Distribution of Al in octahedral and tetrahedral sites of pyroxenes displays that this mineral is crystallized from a magma with ˂ 10% water contents, in low-medium pressure which is in accordance with their formation the depth of 18-30 km. Fe+3 content of clinopyroxenes implies crystallization in high oxygen fugacity condition.
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Volume 25, Issue 1 (4-2017)
Abstract
Gabbrodioritic pluton is located in S-Qorveh in nourthern parts of the Sanandaj-Sirjan Zone. Petrographically, amphibole and plagioclase are main minerals in these rocks. Amphiboles are calcic-type, and their composition varied between ferro-hornblende to magnesio-hornblende. Anortite contents in plagioclases are between 81 to 39 (%) and these crystal are labradore -oligoclase in composition. According to coexist hornblende-plagioclase and Al in amphibole geothermometry methods, temperatures of crystallization are yielded ~723°C. In the later method, data indicates that the investigated rocks were emplaced at average pressure of 3.5 Kbar corresponding to a depth of ~12 Km. Oxygen fugacity was high in magma. Na2O content in amphibole and their calc-alkaline nature show gabbroic diorites are related to subduction setting. Mg#, Al2O3 and TiO2 contents in hornblende indicate mixing of crustal and mantle sources to generate magma of the Darvazeh gabbrodioritic magma. Variations in the composition of plagioclase may be related to H2O content in environment and the role of chemical variation due to input of crustal materials.
Mrs Ashraf Torkiyan, Mr Javad Izadyar, Mrs Zahra Rezvani Mokaber, Mr Aliasghar Sepahi,
Volume 25, Issue 4 (1-2018)
Abstract
Metamorphic area, which is a subject of this study, is located in S-Qorveh (Zarineh region), northwest of the Sanadaj-Sirjan zone. According to the recent dating, the S-Qorveh plutonic body consists of a complex of granitoids, granodiorites, quartz monzonites, and gabbros, have intruded into the host metamorphic rocks, about 149-152 Ma and have generated contact metamorphism. Intrusions of various masses and protolites, such as politic and basic layers, have made metamorphic rocks of this area to be different. Regional metamorphic rocks include slates, schists, and amphibolites which are metamorphosed in the range of middle green schists to the early amphibolites facies. Contact metamorphic rocks include spotted slates, mica hornfels, and cordierite hornfels which have been subject to metamorphism from albite-epidote hornfels to hornblende- hornfels facies. In cordierite hornfelses facis, by getting far from the intrusion, cordierite crystals become smaller in size and larger in number. According to the petrographic evidence, metamorphic rocks of this area have been subject to 3 phases of metamorphisms including probably high pressure regional metamorphism, regional metamorphism, and medium contact metamorphism. To estimate the metamorphism pressure-temperature state of this zone, TERMOCALC computer software and also linear calibrations have been used. Pressure-temperature calculations for regional metamorphic M1, have shown 3.9 Kbar pressure and 539°C temperature. For contact metamorphism M2, by using the software, average pressure of 4.3 Kbar and average temperature of 607°C have been calculated. Also, for the contact metamorphism M2, using the experimental calibration of biotite-muscovite equilibrium, the temperature estimated to be 581.3°C and using chlorite-muscovite equilibrium for this phase (stage) of metamorphism, pressure and temperature have been yielded 3.65Kbar and 620°C, respectively. In generally, results of temperatures for all metamorphic rocks are acceptable and satisfactory, but in contact metamorphic rocks, data of pressure may be higher due to emplacement of the granitoid intrusive body.
Farhad Aliyani, Mohammad Maanijou, Zahra Sabouri, Mirmohammad Miri,
Volume 26, Issue 3 (10-2018)
Abstract
The Kangareh gabbro body is located in south of the Kurdistan Povince and southwest of the Qorveh area. The area belongs to the Sanandaj-Sirjan zone. Tectonic evolutions during Mezozoic and magmatism, due to subduction of the Neo-Tethys oceanic lithosphere beneath the Iran microplate, led to formation of various igneous bodies in this area. Chemical analysis of pyroxene minerals and whole rock analysis show that the Kangareh body has metaluminous nature and belongs to tholeiite to calc-alkaline magma series. The studied samples have geochemical properties of subduction related igneous rocks such as negative Nb, P, Ti and Zr anomalies and positive Rb, Sr and Eu anomalies. The results of this study also indicate that the Kangareh gabbro body formed in an island-arc tectonic setting. On this basis, it can be concluded that there were island-arcs in adjacent to the Iran continental margin (Sanandaj-Sirjan zone) during Mesozoic that were attached to the Iran continental margin (the Qorveh area) after closure of Neo-Tethys ocean.
Mousavi, Torkian,
Volume 29, Issue 4 (12-2021)
Abstract
The Tekieh intrusive complex is located in S-Qorveh in northern parts of the Sanandaj-Sirjan Zone. In this collection, the granite inclusions located in the granite host compound have a diorite composition and the inclusions located in the monzonite host compound have a gabbroic composition. The enclaves are scattered in rounded and elliptical shapes in the host rocks. Generally, they have a sudden contact with the host rock and are composed of igneous minerals. Amphiboles are calcic-type, and their composition is magnesio-hornblende and actinolite. The plagioclases have a range of composition from oligoclase to andesine and oligoclase to bytownite for host rock and enclaves samples, respectively. Based on geothermobarometry studies on amphiboles and also amphibole-plagioclase pairs, the temperatures of 660-5540C and 742-5920C with pressure ranges of 0.3 to 3.62 and 0.21 to 1.8 Kbar were estimated for host rock and diorite enclaves samples, respectively. Oxygen fugacity was high in magma that is consistent with calc-alkaline nature and the formation of rocks in its subduction setting.