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مرکز اطلاعات علمی SID1
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Title: 
Author(s): 

Journal: 

علوم زمین

Issue Info: 
  • Year: 

    0
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    -
Measures: 
  • Citations: 

    0
  • Views: 

    1095
  • Downloads: 

    0
Keywords: 
Abstract: 

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Title: 
Author(s): 

Journal: 

علوم زمین

Issue Info: 
  • Year: 

    0
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    -
Measures: 
  • Citations: 

    0
  • Views: 

    1475
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

View 1475

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Title: 
Author(s): 

Journal: 

علوم زمین

Issue Info: 
  • Year: 

    0
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    -
Measures: 
  • Citations: 

    0
  • Views: 

    879
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Title: 
Author(s): 

Journal: 

علوم زمین

Issue Info: 
  • Year: 

    0
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    -
Measures: 
  • Citations: 

    0
  • Views: 

    789
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

View 789

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Title: 
Author(s): 

Journal: 

علوم زمین

Issue Info: 
  • Year: 

    0
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    -
Measures: 
  • Citations: 

    0
  • Views: 

    1016
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

View 1016

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Title: 
Author(s): 

Journal: 

علوم زمین

Issue Info: 
  • Year: 

    0
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    -
Measures: 
  • Citations: 

    0
  • Views: 

    1125
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    3-18
Measures: 
  • Citations: 

    0
  • Views: 

    2798
  • Downloads: 

    458
Abstract: 

Petrography and geochemistry of the Neyriz Miocene sediments at Roshan Kuh and Kuh-e Asaki sections were carried out to determine their provenance, tectonic setting and pale oclimate conditions in the proximal part of Zagros Basin. The Miocene sediments are limited to the Zagros Main Fault at the northeast and the Neyriz ophiolite zone at the southwest in the Neyriz region. They contain about 700 m red and green sandstone, conglomerate and marl which overlay the Jahrum Formation with a disconformity and covered by Bakhtiari conglomerate with an angular unconformity. Petrography of thin sections indicates that the rock fragments are the most constituent, and then quartz and feldspar respectively. The low compositional and textural maturity of the studied samples (angular grains and poorly sorted sandstones) shows the proximity to the source area. Petrography of the rock fragments and the bulk chemical composition of samples display that their provenance is multiple and the sediments were derived from Sanandaj-Sirjan Zone (Cretaceous limestone- metamorphic rocks- Eocene volcanic) and Zagros Zone (ophiolite sequence- radiolarites- Eocene limestone). Also, point-count data plotted on the QFL and QmFLt triangles indicate the recycled orogen and magmatic arc provenance. Based on geochemical data tectonic setting of Neyriz Miocene sediments is continental island arc and active continental margin. The averages of Cullers’ index, CIW΄ (for calculation of the chemical weathering), ICV Index (to determine the maturity source), and SiO2 versus Al2O3+K2O+Na2O diagram for these sediments show a poor weathering and dry climatic condition during their deposition which is supported by the high percentage of calcareous cement and frequency of the rock fragments. The results of this study suggest a sediment logical framework for the proximal part of Zagros Basin and the Miocene syn-depositional processes.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    19-36
Measures: 
  • Citations: 

    0
  • Views: 

    833
  • Downloads: 

    210
Abstract: 

The study area is located in the Ardabil province and in the north east of Meshkinshahr city. More than 200 small and large Eocene dykes have outcrops in this area with basaltic, tephritic, andesitic and trachy andesitic compositions. Clinopyroxene, plagioclase, analcime and sometimes coarse olivine crystals are present in these rocks. Mineral chemistry studies show that clinopyroxene in rocks is diopside. Existence of normal and reverse zoning in clinopyroxen indicates that differentiation was an effective factor on evolution of the rocks. Enrichment in Ti, Al, Na, and K in pyroxene crystals from the core towards the rim testifies for metasomatism of the rocks. Tectonomagmatic diagrams and comparingthe studied clinopyroxenes' mineral chemistry with those from other tectonic environment suggest that the host rocks are alkaline and are related to volcanic arc setting. According to geotermobarometric studies, clinopyroxenes in the studied rocks were formed at temperature 1150-1200ºC and pressure of 7-14 Kbars. The depth for generation of magma was between 55-65 Km and an average depth of 60 Km was estimated for crystallization of clinopyroxene in these rocks.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    37-46
Measures: 
  • Citations: 

    0
  • Views: 

    693
  • Downloads: 

    91
Abstract: 

The Boushad shear zone (BSZ) is situated in the south of Birjand with at least 45 km length, about 9.2 Km width and strike N90E. The parts of the ophiolite mélange shear zone south of Birjand have changed by this shear zone. The earliest deformation, a polyphasesynmetamorphic deformation which occurred entirely in ductile conditions, D1 and D2 deformation phases are related to this deformation. The D3 deformation affected the area after a period of sedimentation and erosion, Tension gash veins are formed simultaneously. The Strike-slip faults, thrust faults and fault related folds were classified as structures related to the D4 tectonic event, the most recent phase of conflict in the region N055 ± 10E is formed. Degree of convergence of the shear zone is R=0.3, that indicating the formation of a dextral Transpression (Slightly oblique-convergent).

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    47-60
Measures: 
  • Citations: 

    0
  • Views: 

    654
  • Downloads: 

    247
Abstract: 

The study area is located in the SW Rafsanjan city and central Iran. In the area, strike- slip faults effected the Cenozoic unites. This paper analysis subsidiary fault data collected from damage zones associated with the Cenozoic Rafsanjan intraplate right-lateral strike-slip fault systems in SW Rafsanjan city. Fault sets, arranged in a consistent kinematic architecture that is compatible with the Cenozoic regional strike-slip environment. In the paper, kinematic architecture of fault zone interpret in the subsidiary fault. The results show that five peaks is prominence. Angular and kinematic relation among subsidiary fault set show that right-lateral strike- slip and revers fault are the dominant kinematic type in the area. Based on, the angular analysis in the damage zone, we have 5 subsets. 2 subsets of 5 subsets named 1rev (NW-SE trending) and 2rev (E-W trending). In the strike- slip fault mechanism, 3 subsets is demined, three azimuth named 1rl (NW-SE striking), 2rl (E-W striking) and 3rl (WNW-ESE striking). Average strike of set 1rl and 1rev indicate the orientation of the PDZ for fault systems and the PDZ be produced by early localization of the principal displacement zone along pre-existing mechanical discontinuities inherited. Early formation of the PDZ by re-activating pre-existing mechanical discontinuities. The azimuthal value of the faults set in the kinematic architecture are similar to predicted by the simple shear Reidel model. By analysis with kinematic architecture in damage zone of strike- slip fault system indicated that the linking damage zone is very important to increase permeability and created void. The void is low pressure stress and magma can intrude in the area and the dikes formed. The PDZ induced stress and the second and third order fracture is created. Stress analysis in the study are show shear – compression regime convert to compression. The maximum principle axis show N20E to N-S in the Cenozoic. The change of stress regime is correlated by formation fault and fold with E-W trend. The change regime caused reactive pre-exiting fault.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    61-66
Measures: 
  • Citations: 

    0
  • Views: 

    1133
  • Downloads: 

    519
Abstract: 

Issiso hot springs are located 70 km of North of Urmia, within the northernmost part of the Sanandaj–Sirjan zone. The basement of study area is comprised by precambrian metamorphic rocks that consist of gneiss, schist and amphibolite are overlain by younger sediments. The boron concentration in the study area thermal waters is up to 451 mg/l. The warm waters of the region belong to the type of Na- (SO4) -HCO3. The Na/Cl ratio is more than 1 and B/Cl ratio is 0.37. It reflects the impact of specific geological phenomena in formation of rocks. Up to now there is no any geological study of the origin boron in this area. The main aim of this study is to determine geological factor (s) creating this high concentration which caused many environmental problems in the region. In this study it is determined that penetration meteoric water, heated by the deep intrusive magmatic bodies and then rises up with magmatic waters. At high levels, these waters collect in reservoirs including metamorphic host rocks and caused leaching of boron bearing mineral phases. The boron bearing water reaches the surface through faults. Part of the contamination water appears in the form of hot springs and another part through the faults caused spread contamination around the areas. This study shows that high boron contents in the Issiso thermal waters can be attributed to: 1) unstable boron bearing mineral phases same of muscovite, tourmaline, biotite and hornblende in the metamorphic rocks such as gneiss and mica schist, and 2) input of boron-bearing magmatic fluids, related to young volcanic activities. Due to the high temperature play a large role in leaching the boron from the path rocks, it is estimated that high content of boron in Issiso springs may indicate the presence high potential of reservoirs of hot water in depths of earth and also the presence of rocks with high boron content in the path of rising waters. Middle Jurassic is determined for Dalichai Formation in Bar village section. Based on study of three main groups of phytoclasts, marine palynomorph and amorphic organic matter and result of statical studies on the different factors, sedimentary environment of Dalichai Formation in studied section was open marine basin with shallow and low oxygen condition.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    67-78
Measures: 
  • Citations: 

    0
  • Views: 

    1158
  • Downloads: 

    499
Abstract: 

The Khanik-Qazan titanium potential is located at 82 km northwest of Urmia at the NW extremity of the Sanandaj-Sirjan geological zone. This deposit has formed in the Qazan mafic-ultramafic intrusive complex, which is intruded into the early Paleozoic sedimentary rocks. It consists of two general rock units including 1) mafic unit as the main outcrop and 2) ultramafic unit in smaller volume. The mafic rock type is gabbro in general, medium grained and layered, accompanied by anorthosite sill and microgabbro (diabase). Layered mela and meso-gabbro are the main host rocks for titanium mineralization in the studied area. The main minerals of the host rock include clinopyroxene (mainly augite), and calcic plagioclases. Opaque minerals, rare olivine and apatite are the minor minerals and tremolite-actinolite, epidote, zoisite, chlorite, albite, sericite and calcite are the secondary minerals. Saussuritization, uralitization, sericitization and chloritization are the main alterations on the main silicate minerals. Ilmenite, titan omagnetite, magnetite, and some hematite and pyrrhotite are the main primary opaque ore minerals. Open-space filling textures including granular and exsolution are the major textures of the ore, while, spherical, martitization and mylonitization are the minor textures. Total abundance of ilmenite, magnetite, titan omagnetite based on the studied polished sections ranges between 5 to 12 vol%. Oxide and silicate phases are associated with the host rocks due to the relatively low oxygen fugacity, which don’t occurred in complete separation of the silicate melt from oxide melt. Based on geochemical studies, the primary magma had an alkaline to sub-alkaline (mainly tholeiitic trend) series nature. According to the mineralogical and petrographical evidence and chemical analyses, the Khanik-Qazan ilmenite-titanomagnetite deposit is similar to the low grade apatite-ilmenite–magnetite Kauhajarvi deposit and Lumikangas deposits, in western Finland.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    79-90
Measures: 
  • Citations: 

    0
  • Views: 

    890
  • Downloads: 

    558
Abstract: 

Carbonate deposits of members 1 to 2 of the Mila Group (Middle Cambrian) in Central Alborz that call the Deh-Sufiyan Formation in this research, were studied in Shahmirzad, Tueh-Darvar, Mila-Kuh and Deh-Molla sections. The Unit 2 of Deh-Sufiyan Formatrion in Central Alborz of Northern Iran consists mainly of shallow marine carbonates and contains a variety of limestone conglomerates. Limestone conglomerate is an important component of Unit 2 of Deh-Sufiyan Formatrion, but its origins remain enigmatic. These limestone conglomerates have a diverse set of characteristics that range from clast to matrix supported with scattered flat pebbles. These conglomerates are largely comprised of oligomictic, rounded lime–mudstone clasts of various sizes and shape (equant, oval, discoidal, tabular, and irregular). According to composition and characteristic sedimentary structures and fabric, limestone conglomerates in the Unit 2 of Deh-Sufiyan Formatrion consist of: (1) Intraformational limestone conglomerate beds were formed by depositional processes (2) Limestone pseudoconglomerate beds were produced by diagenetic processes. The common characteristics of the Unit 2 of Deh-Sufiyan Formatrion pseudoconglomerates, such as oligomictic lithology of lime–mudstone clasts, mosaic fabric, disorganized/edgewise fabric, variable and gradational fabric, transitions from adjacent or underlying facies and the complete lack of depositional structures, are typical of pseudo conglomerates formed by early diagenetic sediment deformation under shallow burial conditions. These characteristics are different from those of intraformational limestone conglomerate showing primary depositional features such as normal or inverse grading, internal stratification, (hummocky) cross-stratification and sharp erosional bases. Diagenetic conglomerates in ribbon rocks resulted from soft-sediment deformation of ribbon rocks during early diagenesis. In contrast, the dimension and thickness, sizes of the clasts, clast-rich beds, size ingredient of matrix, tendency to amalgamate with amalgamation scours within depositional conglomerates suggest that high energy and strong erosion above storm wave base was responsible for the disintegration of the carbonate material.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    91-98
Measures: 
  • Citations: 

    0
  • Views: 

    958
  • Downloads: 

    499
Abstract: 

A NW-SE trending ductile shear zone has been generated in the metamorphic rocks of the southwest Golpaygan. Different pellitic and psammitic schists, meta-carbonates and igneous rocks were strongly deformed in this ductile shear zone and produced mylonites and ultra-mylonites. Structural analysis indicates three stages of foliations in the metamorphic rocks. Geometry and kinematics of the fabrics in Nowgan shear zone are divided into two northeastern and southwestern parts (limbs of Nowqan antiform). Mylonitic foliation moderately to steeply dip towards northeast in the northeastern part but dips to the southwest in the southwestern part. Mineral and stretching lineation, are shallowly to moderately plunging to the east-southeast in the northeastern part of the shear zone and, to the west-northwest in the southwestern part. The microstructural indicators of shear sense cleared that the northeastern part dextrally displaced along strike with normal component and the southwestern part sinisterly displaced with reverse component at the present situation. The fabrics evidence clear that this ductile shear zone were originally right-lateral strike–slip shear zone and during its structural evolution it was rotated around its strike during later folding stage. Structural analysis of the surrounded rocks of the shear zone indicates three superposed foliations. The mylonitic foliation in the shear zone and the axial plane foliations of the second stage folding are sub-parallel. Plunge directions of the second stage folds axes and the mineral/stretching lineation are also sub-parallel. Therefore, the initiation and development of the shear zone were synchronous with the second stage folding event.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    99-108
Measures: 
  • Citations: 

    0
  • Views: 

    837
  • Downloads: 

    249
Abstract: 

In the present study, erodibility of various deposits of Sefidrud Delta was evaluated based on effective engineering geological factors. First of all, the study area was studied from geology and sedimentology point of view and various deposits were identified in this area. Then the engineering geological characteristics of deposits were determined based on existing geotechnical data, field investigation and performance of 32 dynamic cone penetrometer test (DCP). Finally, by development a simple and precise method, the erodibility of various deposits was evaluated based on texture and shear strength factors. The results show that the erodibility of deposits has a close relationship to the sediment logical characteristics and erodibility could be analyzed regarding the geological history of deposits. According to the results of this research, natural levee deposits have highest erodibility and in other hand old deltaic deposits have lowest erodibility in Sefidrud Delta area. Such researches have a main role in sustainable development of the study area.

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Author(s): 

HOSSEINI B. | AHMADI A.R.

Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    109-120
Measures: 
  • Citations: 

    0
  • Views: 

    834
  • Downloads: 

    101
Abstract: 

Deformed granitoid rocks from North Saman represent part of magmatic activity in the Sanandaj-Sirjan zone during the Mesozoic. The granitoid rocks intruded as separate intrusions into the metamorphic rocks with protolith ages of the Palaeozoic and Mezosoic. These granitoids are deformed as a result of subsequent tectonic activities. Zircon U-Pb ages of crystals separated from the granitoid rocks gave ages of 182 ± 4 Ma and indicate that the granitoid rocks crystallized at the Toarcian stage of the lower Jurassic. The major and trace element goechemistry suggests a subduction-related, active continental margin setting for the granitoid bodies. The occurrences of numerous Jurassic granitoids reveal the importance of magmatic activities during this period in the Sanandaj-Sirjan zone.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    121-130
Measures: 
  • Citations: 

    0
  • Views: 

    908
  • Downloads: 

    106
Abstract: 

Before the Cold War, strategic materials supply and related studies were maily affected by military ‎‎ competition between the East and the West. The example is the assessment of the geopolitical risk factors by ‎ Anderson for the North Atlantic ‎ Treaty Organization. However, after the Cold War and the collapse of the Berlin Wall in 1989 and the development of Chinese economy, more and more Western countries began to be concerned of the vulnerability against the suppliers of minerals. The main reason for this is geopolitical developments and turning of militarism and geostrategy to G eoeconomics and priority of economy. The methods for assessment of the post-Cold War are based on confrontation ‎ between the north and the south and provide more economic security or economic power and also provide needed ‎ goods and protection of the environment. ‎ New methods started with research of the National Council of United States of America by innovating the two-dimensioned criticality matrix including economic importance and supply risk, and Graedel studies actually follow its principles. Investigations by Geological Survey and Department of Defense in the United States, the European Union and German industry show that fluorspar is a strategic mineral. Economic value of fluorspar is from it usage in production of steel, aluminum, hydro fluorocarbon, ‎teflon and new and clean energy. Investigations on fluorspar producing countries during the last fifteen years in this research show that although Iran has achieved the 10th rank in the world with one percent of the world production, but still is one of the main importer of intermediate goods made using this mineral among neighboring countries. Therefore, the first step in improving the country's situation in this regard is essential investment for systematic and in-depth exploration, especially in the central Alborz, with the goal of increasing fluorspar reserves and to supply raw materials for the aluminum industry in the country, the industry in which countries at the south of Iran as competitors have been very active by large investments, due to low cost energy.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    131-142
Measures: 
  • Citations: 

    0
  • Views: 

    798
  • Downloads: 

    588
Abstract: 

From Late Devonian-Early Carboniferous strata in the Kerman area fourteen chondrichthyan taxa were identified. The abundance of chondrichthyan teeth in Famennian strata is considerable. The high abundance of protacrodonts and larger proportion of shallower shelves of pheobodonts appeared to dominate in a shallow environment at the Famennian. The chondricthyan assemblage from the Famennian of the Hutk section resembles the Chahriseh fauna in Esfahan district that reveals similar palaeoenvironmental conditions in Central Iran basin. The occurrence of Deihimmansureae in duplicate Zone marks the youngest record for the species up to Early Tournaisian.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    143-154
Measures: 
  • Citations: 

    0
  • Views: 

    1206
  • Downloads: 

    233
Abstract: 

The early carboniferous Mobarak Formation was studied in southern flank of Ayenehvarzan–Dalichai anticline, in Aru and Seyedabad sections, east of Tehran. The aim of this study is to determine microfacies, interpretation of depositional environments and sequence stratigraphy of the Mobarak Formation. In this study, the thickness of Mobarak Formation in Aru and Seyedabad sections varies from 133 to 65 meters and consists of limestone with intercalations of shale and marl. According to lithological characteristics, the Mobarak Formation subdivided into several rock units. The Mobarak Formation is disconformably overlain by Jirud Formation and underlain by Dorod Formation. Ten microfacies have been recognized on the basis of depositional remarks and petrographic analysis. These carbonate facies belong to 4 major sub-environments including beach/tidal flat, lagoon, barrier/sand shoal and open marine. These facies deposited in a homoclinal carbonate ramp and include two sedimentary sequences.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    155-164
Measures: 
  • Citations: 

    0
  • Views: 

    1109
  • Downloads: 

    515
Abstract: 

The Qahr-abad fluorite deposit is located ~58 km southeast of Saqqez city, Kurdistan province. This deposit is developed as scatter lenses, veins, and veinlets (stockwork structure) within carbonate rocks. Violet, green and colorless fluorites are recognized. Quartz, dolomite, calcite and barite are gangues. REE geochemistry of the deposit shows that the REE content of the fluorites lies between 20.18 and 48.38 ppm. The relatively higher concentration of LREEs in violet and colorless fluorites suggests that they formed at the first stages of mineralization. Calculation of Eu anomalies indicates that the fluorites formed in an alkaline to neutral and to some extent oxidizing conditions because the Eu anomaly cover a narrow range around 1. Negative Ceanomaly also confirms the oxidizing conditions for mineralizing fluids. Finally, by the studies of REE geochemistry it can be concluded that the Qahr-Abad fluorite deposit is a product of hydrothermal activity of epithermal type and the mineralizing fluids were of magmatic or a basin fossil fluids origin. Magmatic activities in this district, can explain the hydrothermal nature for the deposit.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    165-178
Measures: 
  • Citations: 

    0
  • Views: 

    1276
  • Downloads: 

    719
Abstract: 

Dariyan formation is one of the oil reservoirs in the south pars field. This formation has been studied in wells SPO-1, SPO -2 and Spo-3. Thickness of Dariyan formation in mentioned wells are 109, 113 and 114 meters respectively. Based on the studies of thin sections from the Dariyan formation of three above mentioned wells, nine carbonate and one detrital facies have been identified within four facies associations including tidal flat (Mudstone), lagoon (Bioclast mudstone to wackstone, Bioclastpeloidwackstone to packstone, Bioclast peloidpackstone to grainstone, Algal boundstone), Mid ramp (Echinoid mollusk wackstone to packstone, Orbitolinawackstone to packstone, Framestone, Floatstone) and outer ramp (Shale). Facies studies indicate that Dariyan formation has been deposited in a homoclinalramp. The Dariyan formation has been affected by four diagenetic stages, including marine, meteoric, burial and uplift. Themost important identified diagenetic processes are micritization, bioturbation, geopetal, physical and chemical compaction, cementation, neomorphism, replacement, dissolution, fracturing and filling. Among the all diagenesis process, dissolution and fracturing are the major processes improving reservoir quality. In Contrary, physical compaction and especially cementation are the main processes reducing reservoir quality. Dissolution process with generating secondary porosity consists of vuggy and moldic, has important effect on increasing of porosity. Most of the dissolution features have been produced during the meteoric diagenesis and less through burial diagenesis. Dissolution process with develop the vuggy pores caused to connect them in some case and also affected on fractures, stylolites and previous diagenetic cements in upper and lower members of Daryian formation whicheventually has been increased permeability and reservoir quality. Also, Fracturing, the main other diagenetic process with connect the some individual vuggy and moldic pores together has effective role to increase the permeability and reservoir quality in upper and lower parts of Dariyan formation.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    179-198
Measures: 
  • Citations: 

    0
  • Views: 

    876
  • Downloads: 

    733
Abstract: 

The study area is located at the center of the Lut area and the southern part of the Eocene- Oligocene Lut volcano-plutonic belt. The main exposed igneous rocks include widespread and thick units of Middle Eocene volcanic (basaltic andesite, andesiteand trachy-andesite) and Eocene-Oligocene volcanic-subvolcanic (dacite and rhyodacite) with related tuffs, intruded by microdioritic stock and dykes of Oligocene with g abbrodiorite to quartzdiorite compositions. Texture is dominantly porphyritic and the main minerals are plagioclase, clinopyroxene, hornblende, K-feldspar, quartz and minor amounts of biotite with apatite, zircon, rutile and opaque minerals as accessory phases. These rocks with predominant K-high calc-alkaline to shoshonitic affinities, are I type and metaluminous and are characterized by LILE, LREE and Th enrichment relative to HFSE, depletion in Nb, Ti, Ta and weak depletion in HREE and Y. These features are characteristic of the post-collisional calc-alkaline rocks along with a continental active margin tectonic setting. In spite of the low ratios of Nb/U, Nb/La and Ce/Pb, the Sm /Yb (1.6-2.1) ratio reveals low contamination of magmas with relatively thin crust which is in accordance with low crustal thickness in this area (36-38Km). According to geochemistry of trace elements and REEs, the main cause of magmatism in Mahour was melting of a metasomatized lithospheric mantle (E-MORB like) with spinel lherzolite composition accompanied by very small amount of garnet in the presence of phlogopite. On the basis of the phenocrysts assemblage, REE pattern with negative Eu anomaly (Eu/Eu*=0.63-0.9) and also La/Yb calibration to crustal thickness, magmas have undergone relatively dry crystallization in the magma chamber at shallow depths (<40 Km). Non-equilibrium textures, multiple element and REE pattern, abundances of Y and K2O/Na2O in Mahour igneous rocks show contamination and mixing with acidic magma of amphibolitic lower crust due to temperature of mantle magma and AFC process played important roles in magma evolution, in addition to fractionation. La vs. La/sm diagram and Nb/Ta=10-13.3 illustrate partial melting and the role of lower crust in magma evolution, respectively. The presence of hornblende more than biotite, mantle-crust source, the contents of Sr, Rb, Ba, Ce and Rb/Zr, the tectonic setting discrimination diagrams and the regional geological evidences such as closing age of Neotethys, Naeen-Baft and Sistan oceans and cutting ophiolitic mélange by Eocene lavas around Birjand, all indicate Tertiarymagmatism in the Mahour area and therefore Lut in a post-collision tectonic setting. Calc-alkaline affinity and subduction geochemical signature in these rocks are related to metasomatized mantle source inherited from the low-angle subduction of Arabic plate (Neotethys oceanic crust) beneath the Central Iran plate in Mesozoic. The Probable mechanism for this magmatism is slab retreat and extentional collapse after orogenyin which Nehbandan and Nayband streak-slip and shear faults activities and also crust thickness had important role in emplacement of them. The igneous rocks have been affected by hydrothermal alteration. Zinc and copper mineralization formed as veins, veinlets and space filling among breccia fragments in fault crushed zone and predominantly in dacite-rhyodacite unit.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    199-208
Measures: 
  • Citations: 

    0
  • Views: 

    843
  • Downloads: 

    421
Abstract: 

This study investigates the Lower Cretaceous sedimentary succession comprising Sarcheshmeh Formation and Sanganeh Formation in the western part of Kopet-Dagh basin (Ghaleh zoo Section) from the standpoint of Calcareous Nannofossils. The results reveals presence of 60 species from 33 genera of 15 families. Based on the index nannofossil taxa, the upper part of NC6, NC7A, NC7 (B& C) and NC8 (A& B) nannofossil zones (equivalent to the upper part of of CC7a, CC7b and CC8 zones), are present in this section. The calcareous nannofossils found in this section point to an Early Aptian to Late Aptian age of deposition for the rocks of Sarcheshmeh Formation and Late Aptian to Early Albian for the rocks of Sanganeh Formation.

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Author(s): 

HOSSEINI S.Z.

Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    209-220
Measures: 
  • Citations: 

    0
  • Views: 

    733
  • Downloads: 

    297
Abstract: 

The Eocene mafic lava flows of Sarcheshmehare cropped out in the southwest of Rafsanjan area at the central part of the Urmia – Dokhtar magmatic belt. The rocks are basalt, basaltic andesite and andesite in composition and consist of clinopyroxene+plagioclase ± olivine ± hornblende phenocrysts. The geochemical characteristics show calc-alkaline nature for the lavas that are formed in an active continental margin tectonic environment. Low amounts of MgO, Cr and Ni in the Sarcheshmeh Eocene basaltic lavas points to the role of evolution in their parental magma. The MORB normalized multi-element patterns of the lava flows show enrichment in LILE (e.g. Sr, K, Rb and Ba) and depletion in HFSE (e.g. Ta, Nb and Ti). The Chondrite-normalized REE patterns show moderate enrichments in LREE with (La/Yb)n<3 for all samples. The geochemical features such as (La/Yb)n<2, the Yb contents and also using petrological diagrams based on trace and rare earth element ratios (e.g. Th/Y, Nb/Y, Ta/Yb, Ce/Yb) indicate that the Sarcheshmeh Eocene basaltic lavas were generated from a metasomatized lithospheric mantle source at the spinel stability depth.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    221-234
Measures: 
  • Citations: 

    0
  • Views: 

    808
  • Downloads: 

    593
Abstract: 

Sarvak Formation (Cretaceous) is considered as one of the most prominent oil reservoirs in the south of Iran and hosts significant volume of oil accumulation in the Persian Gulf basin. In the present research plan, in order to evaluate the hydrocarbon generation capacity of this formation, cores, cuttings and oil samples collected from producing oil and gas wells located in block D underwent detailed geochemical investigations which were in the Iranian sector of the Persian Gulf. Correlation is defined as the geochemical comparison between hydrocarbons themselves, or also hydrocarbons with source rocks, and furthermore defining the quality of the genetic relation between them. In order to achieve this goal a variety of gadgets and parameters are used, some of them being biomarkers and stable isotopes. The results obtained from geochemical analyses including primary analyses (pyrolysis rock - eval), bitumen extraction and separation, complementary analyses (gas chromatography), gas chromatography-mass spectrometry and stable isotope studies on samples indicate that kerogen of studied samples is a combination of types II and III and it implies that most organic matter generating hydrocarbon wereformed in a marine environment along with a little entering from land. The hydrocarbons existing in Sarvak Formation were generated from a semi carbonated clastic source rock and were deposited under a reducing or semi-reducing environment. The saturate fractions analyzed using GC and GCMS techniques indicate the lack of environmental biodegradation in the studied samples. The inter bed shaly-marl samples of the Sarvak Formation show a fair to good hydrocarbon potential. The set of under study samples are located in the beginning of the oil generation window (late diagenesis) and early catagenesis in terms of their maturity degree. Furthermore, hydrocarbons show a paraffinic-naphthenic characteristic. It seems the shaly-marl layers existing in some parts of the Sarvak Formation (Ahmadi member), in Block D, in the Persian Gulf, have been the cause for the generation of hydrocarbons available in the Sarvak reservoir.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    235-246
Measures: 
  • Citations: 

    0
  • Views: 

    1104
  • Downloads: 

    552
Abstract: 

The Senjedak-I prospect area is one of the six eastern anomalies of Sangan iron mine. Geologic units in the area consist of Jurassic shales and sandstones, skarn rocks and Tertiary biotitemonzonite and biotitesyenogranite intrusive rocks. Due to severe alteration of biotitemonzonite porphyry intrusive, geochemical studies have focused on the biotitesyenogranite. This granular intrusive consists of K-feldspar, plagioclase, quartz, biotite and accessory minerals such as zircon, titanite, apatite and magnetite, with weak sericitic, argillic and silicic alterations. Biotitesyenogranite is rich in silica (68.7 to 77.2 wt.%) and is chemically peraluminous which is formed by fractional crystallization from an I-type granitic magma poor in P (average 0.1% P2O5). This intrusive rock falls in the range of I-type granites and is oxidized. REE values indicate negative Eu anomaly, mild enrichment of LREE, a positive pattern close to flat HREE and negative anomalies of Ba, Sr, La, Ce, Ti, and Eu. On the basis of Rb, Nb, Yb, Hf, and Ta contents, tectonic setting of samples fall in Volcanic Arc Granite (VAG) and Post Collision Granite (post-COLG) divisions. The most important event in the Senjedak-I area was infiltration of Fe-bearing fluids through the carbonate rocks, their recrystallization, skarnification (prograde and retrograde), and iron ore deposition that could be explained by occurrence of calc-silicate minerals. The skarn has been separated into 4 zones on the basis of abundance of the calc-silicate minerals: garnet skarn, phlogopiteskarn, epidoteskarn, and amphibole skarn. According to Electron Probe Micro Analysis (EPMA), the composition of garnets is andradite-grossular (An 100-42.6 Gr 0-55.32 Sps 0-1.39) and pyroxenes are diopside-hedenbergite (Di 63-92 Hd 4-35 Jo 0.5-3.9). Mineralization in this prospect area formed as stratabound and massive bodies in the carbonate rocks. The main ore mineral is magnetite (40%) with minor amounts of pyrite. Secondary minerals are hematite and malachite. The FeO content in the magnetite is 91.7% and the S content is 0.03%. The Senjedak-I anomaly is located along the eastern part of the Dardvay deposit (in central division of the Sangan mine). The geochemical similarities of intrusive rocks, chemistry of skarn minerals, and pyroxene and garnet composition confirm that the Senjedak-I is a part of Dardvay, which is separated by a main fault with southeast-northwest trend.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    247-258
Measures: 
  • Citations: 

    0
  • Views: 

    1478
  • Downloads: 

    233
Abstract: 

Sahebdivan area is located at 20. km of Meshkinshahr in Ardebil province. The study area is comprises of volcanic rocks and intrusive masses consisting of quartz monzonite and granite along with several vast epithermal alterations. The main objective of this paper is to recognize the present alteration zones indicating metal promising areas using geophysical methods such as induced polarization (IP) surveying and resistivity (RS) in order to assess the presence of minerals and delineate the subsurface masses at depth. Therefore, IP / resistivity survey was carried out based on rectangular array in the area and their corresponding maps were prepared. Accordingly, their promising anomalous zones for mineralization were initially detected. Furthermore, a new IP survey was attempted based on a dipole-dipole electrode array for detailed potential mapping. Considering IP/RS pseudo-sections, the position, depth, intensity and extent of mineralization was defined. Correlating the anomalous zones obtained from geophysical results with Lithology and alteration zones in the area indicate Cu mineralization along E-W trend in Sahebdivan which is associated with increase in chargeability and reduction in resistivity. Furthermore topographic corrections were attempted resulting in anomalous halos enhancement. Discriminating the important alteration zones in the area were carried out based on chargeability variations where higher chargeability indicate phyllic alteration with pyrite and in contrast the Potassic alteration with low chargeability that coincide with igneous intrusive. It can be deduced from this study that the porphyry micro quartz monzonite -micro quartz diorite generator fluids was recognized as source of mineralization along with surrounding andesite–dacite andesite as source of the anomalous zones in Sahebdivan area. Summing all the evidences from field studies and their compliance with geophysical results, Lithology, alterations and ultimately considering the susceptible mineralization zones, the optimal drilling points was proposed with priority of SABH-1 according to the Potassic zone in terms of potential copper mineralization.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    259-270
Measures: 
  • Citations: 

    0
  • Views: 

    1410
  • Downloads: 

    462
Abstract: 

Aliabad Mousavi- Khanchy Cu occurrence is located in the Tarom area, 30 km east of Zanjan. Rock units exposed in this area consist of Eocene volcanic and volcano-sedimentary units (equal to Karaj Formation) which are intruded by Oligocene quartz-monzonitic plutons. In this area, Cu mineralization occurs as Cu-bearing quartz veins and veinlets within the intermediate tuffs and andesitic lavas. Based on microscopic studies, ore minerals include chalcopyrite with minor pyrite and oligist, and quartz and chlorite are present as gangue minerals in the Aliabad Mousavi- Khanchy Cu occurrence. The ore minerals show disseminated, vein and veinlets, breccia, open space filling and replacement textures. Alteration is restricted to the silicified and chloritic altered parts of the ore zones. Two stages of hypogene and supergene mineralization can be distinguished at the Aliabad Mousavi-Khanchy Cu occurrence. The hypogene stage of mineralization is progressed from disseminated crystals of pyrite and chalcopyrite within the tuffs and lavas (substage 1) to quartz- chalcopyrite- pyrite‒cemented veins and breccias (substage 2), individual or sets of quartz veins and veinlets (substage 3) and finally quartz- oligist veins and veinlets (substage 4). Malachite, azurite and Fe-hydroxides with veins and veinlets and open space filling textures are formed during supergene stage. REE pattern of the host rocks and the mineralized samples indicate that mineralized samples are enriched in REE. This signature may indicate high concentration of REE in ore-forming fluids and/or high water/rock interaction at Aliabad Mousavi- Khanchy area. Enrichment of ore-forming elements (Cu, Pb, Zn) in ore zones is also specifies leaching of elements from altered host rocks to ore zones by ore-forming fluids. Characteristics of Aliabad Mousavi- Khanchy Cu occurrence are comparable with vein type Cu deposits.

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Author(s): 

NAGHAVI M. | RAHIMI H. | MORADI A.

Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    271-280
Measures: 
  • Citations: 

    0
  • Views: 

    813
  • Downloads: 

    418
Abstract: 

The energy of a seismic wave decays while passing througha “real” medium such as the earth which is not completely elastic. Scattering and attenuation of high-frequency seismic waves are substantial parameters to quantify and to physically characterize the earth medium and from which useful information on medium properties can be inferred. The coda waves in seismograms are one of the most prominent observations supporting the existence random heterogeneities in the earth. Determination of source parameters must take into account the proper attenuation characteristic of the wave path. Moreover, it is essential for seismic risk studies and seismic hazard assessment, and consequently for seismic risk mitigation and engineering seismology. ...

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    281-290
Measures: 
  • Citations: 

    0
  • Views: 

    1019
  • Downloads: 

    572
Abstract: 

Dariyan Formation deposited in two different sedimentary settings. In some places it consists of shallow Limestone with algae and Orbitolina and in the other places in addition to limestone, it represents black shales and marls associated with planktonic foraminifera and radiolarian. In this research Draiyan Formation was studied in order to microfacies, depositional model and sequences stratigraphy of two sections so called, Kuh-e Gadvan and Kuh-e Banesh in high Zagros belt. Detailed petrographic studies led to the recognition of five main facies belts including: lagoon, bar, shallow open marine, outer ramp and deep marine. According to the vertical and lateral variations of facies, the Dariyan Formation deposited on a carbonate ramp platform and intrashelf basin. Depositional sequences have been presented on the basis of analysis of facies, fauna assemblages, Gama and Neutron logs. Three 3 rd orders depositional sequences have been recognized during deposition of sediments. There is Type I sequence boundary in the top of third sequence and the other two sequences was considered as Type II sequence. Sea level fluctuations of the studied area correlated with Arabian platform and these changes follow of regional factors.

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2016
  • Volume: 

    25
  • Issue: 

    100
  • Pages: 

    291-298
Measures: 
  • Citations: 

    0
  • Views: 

    579
  • Downloads: 

    87
Abstract: 

In the Ahmadabad Khartouran region located at 175 Km southeast of Shahrood, a considerable number of adakitic domes crop out, which are intruded into the Paleocene- Eocene volcano sedimentary rocks. Lithological compositions of these domes include andesite, trachyandesite and dacite. Pyroxene (augite), green hornblende and plagioclase are typical mafic and felsic rock forming minerals. With respect to low HREE and high LREE along with other characteristic such as silica content (58.91-63.41), Na2O more than 3%, Al2O3 more than16%, Yb less than 1.8 ppm, Y less than 18 ppm and K2O/Na2O ratio between 0.98- 2.3, these rocks can be classified as high silica adakite. Enrichment of LREE relative to the HREE and depletion of Nb, Ti, and high concentration of Rb, Ba, K and Th, imply crustal contamination of the mentioned adakitic domes. Enclaves with different sizes and compositions were seen in these domes which indicate contamination and magma mixing with continental crust. Petrographic and geochemical evidence show that the magma forming these rocks originated from melting of subducted metamorphosed Neotethys oceanic slab (Sabzevar – Darouneh branch) at the Peak-T conditions of amphibolite facies.

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