@article { author = {}, title = {Geochemistry and petrogenesis of dyke swarms in NW Sinai, Egypt: a case of transition from compressional to extensional regimes during the late Neoproterozoic}, journal = {Quarterly Journal of Tethys}, volume = {2}, number = {3}, pages = {160-177}, year = {2014}, publisher = {Payame Noor University}, issn = {2476-7190}, eissn = {2345-2471}, doi = {}, abstract = {Dyke swarms emplacement constitutes one of the conspicuous features of the Neoproterozoic Arabian-Nubian Shield (ANS) (~950-540Ma). Based on field investigations, petrographic and geochemical characteristics the dyke swarms in NW Sinai (Egypt) comprise of mafic (dolerite-trachy-basalt-basalt), intermediate (basaltic-andesite trachy-andesite) and felsic (rhyodacite-rhyolite) varieties. Geochemically, all varieties are calc-alkaline with the exception of few mafic varieties that show weak alkaline affinity. Increasing SiO2 is accompanied by enrichment in Na2O, K2O and depletion of TiO2, FeOt, MgO, CaO, P2O5, Co, Sr, Ba, Zr and Y. There is a compositional gap between the mafic, intermediate and the felsic dykes perhaps indicating more than one magma source. Although, Geochemical signatures of the investigated dykes swarms suggest that they are related to subduction processes,but according to tectonics and field relationships the studied dykes represent a post-orogenic or, at least, represent a transitional tectonic setting between Subduction and extension phases. The mafic dykes resulted from a lithospheric mantle-enriched material during a previous subduction event (> 300 Ma) by small degree of partial melting.The intermediate dykes are most probably produced by partial melting of basaltic magma that followed by fractional crystallization processes. Fractional crystallization processes are dominated during the evolution of the most evolved intermediate samples; due to consumption of pyroxene, amphibole and plagioclase. The felsic dykes most probably evolved by partial melting of a lower mafic crust which led to the formation of a rhyolitic magma. In addition, the investigated samples showed remarkable crustal contamination during their formation. The investigate dyke swarms were emplaced at a post-orogenic extensional collapse event transitional between volcanic-arc and within-plate environment during the late stages of the Late Neoproterozoic juvenile Pan-African crust of the Sinai Peninsula.}, keywords = {Neoproterozoic,Dyke Swarms,Post-Orogenic,Multiple Magma Source,Sinai Peninsula}, url = {https://jtethys.journals.pnu.ac.ir/article_2824.html}, eprint = {https://jtethys.journals.pnu.ac.ir/article_2824_cd51f250268a3545e313aca0aad406c8.pdf} } @article { author = {}, title = {Field observations, Petrography and microstructures study of Jebale Barez Plutonic complex (East - North East Jiroft)}, journal = {Quarterly Journal of Tethys}, volume = {2}, number = {3}, pages = {178-195}, year = {2014}, publisher = {Payame Noor University}, issn = {2476-7190}, eissn = {2345-2471}, doi = {}, abstract = {Jebale Barez Plutonic Complex Is composed of granitoid Intrusive Bodyes and Is located In the East - North East Jiroft and  southeastern province of Kerman on The lengths of the 57° 45' east to 58° 00' and Northern latitudes  28° 30' to 29° 00'. Plutonic Complex composed of granodiorite, quartzdiorite, Monzogranite and Porphyritic granite. The microstructures observed in thin sections from about 200 samples in this study were grouped into tree types: (i) magmatic microstructures; (ii) submagmatic microstructures and (iii) Mylonitic microstructures. Magmatic microstructures and submagmatic microstructures located in the central of Mijan and less than in the central of Hishin and Korour area but Mylonitic microstructures observed in all of rims Jebale Barez Plutonic Complex. Field observations, Major structural and morphologic elements suggested that Mijan area is old caldera and Evidence suggested that Magma implemented Sill form in the Jebale Barez Plutonic Complex. Therefore it is assumed that the whole JBPC is located in shear zone. Mijan Old Caldera is feeder zone and magma has been intrusion. Magma has been percolated through Mijan caldera and emplacement Forms of Sill along the shear zone during various periods.}, keywords = {Granite,Microstructures,Jebale Barez,Urumieh-Dokhtar magmatic belt}, url = {https://jtethys.journals.pnu.ac.ir/article_2825.html}, eprint = {https://jtethys.journals.pnu.ac.ir/article_2825_9cc05da0294779f7eac26a0ff2ca3de5.pdf} } @article { author = {}, title = {Assessment of heavy metals contamination in urban topsoil from Arak industrial City, Iran}, journal = {Quarterly Journal of Tethys}, volume = {2}, number = {3}, pages = {196-209}, year = {2014}, publisher = {Payame Noor University}, issn = {2476-7190}, eissn = {2345-2471}, doi = {}, abstract = {An increase in heavy metal pollution in the soils of Arak due to industrialization and urbanization has become an environmental problem. The region hosts several industrial facilities which are the main source for hazardous wastes which include electric, metal, automotive supply industry, food, machinery, and chemicals. Soil samples were collected from these industrial areas in the central and around of Arak city and analyzed for their metal contents. Results of the analysis show that the soils are characterized by high concentrations of Ni and Cu. Concentrations of As, Pb, Zn, Cr and Co elements do not exceed the permissible levels in the most of the samples. Concentrations are 3.01- 17.36 mg/kg of Pb, 9.60-195.55 mg/kg of Cu, 12.20- 63.12 mg/kg of Ni, 0.85- 69.91 mg/kg of Zn, 1.41- 4.50 mg/kg of As, 25- 130 mg/kg of Cr and 7.54- 24 mg/kg of Co. Application of factor, cluster and correlation analysis showed that heavy metal contamination in soils originates from industrial activities and heavy traffic which are of anthropogenic origin. Contaminations in soils were classified as geoaccumulation index, enrichment factor, contamination factor, and contamination degree. Contamination degree values indicate that heavy metal pollution levels of soils collected from industrialization sites are greater than those of distal parts of industrialization. Spreading of hazardous wastes from industrial facilities in the study area via rain or wind is the main source of soil pollution. In addition, agricultural wastes and traffic-related metal pollution is also observed.}, keywords = {Heavy metal contamination,Industrial areas,Arak,Iran}, url = {https://jtethys.journals.pnu.ac.ir/article_2826.html}, eprint = {https://jtethys.journals.pnu.ac.ir/article_2826_68f2b4b78d69f7e17bffc3ab3f03e0a7.pdf} } @article { author = {}, title = {Effective Factors on Environmental distribution of trace elements in the ChahMorra Cu Occurrence, Shahrood}, journal = {Quarterly Journal of Tethys}, volume = {2}, number = {3}, pages = {210-227}, year = {2014}, publisher = {Payame Noor University}, issn = {2476-7190}, eissn = {2345-2471}, doi = {}, abstract = {The Chah Morra Cu occurrence is located 15 to 20 km north of Toroud village, south of Shahrood. In this area, Cu deposits are hosted by the andesitic sequence and most of rocks in this area are composed of andesite. Veins contain minerals such as digenite, bornite, covellite, malachite, cuprite, tenorite, native copper and Fe oxide and hydroxides. Also some orthomagmatic magnetite and chalcopyrrhotite are observed in polished sections. Study of heavy minerals shows that some minerals such as magnetite, titanomagnetite, hematite, limonite, oxidized pyrite, pyroxene, amphibole, epidote, oligist, ilmenite, zircon, apatite, barite and rutile are accumulated in stream sediments. Studies on 65 stream sediment samples analyzed for 44 elements by using ICP-OES method indicates that the Cu mineralization have not polluting effect, however the Chah Morra stream sediments indicate enrichment factor values higher than 1 for some elements including Bi, Co, Cu, Fe, Nb, Ni, Rb, U, Yb. Also the data higher than the standard values show that Cr, Pb, Sc and W in addition to above-mentioned elements are higher than the standard values. Calculation of Igeo shows that the Bi and Nb (second class of pollution), are among the pollutant elements in this area. Calculation of correlation coefficient and dendrogram shows that the pollutant elements aren’t related to copper. Studies on Cu pollution were carried out on 276 litho-geochemical sample analyses. Analytical results show that contaminated points are accompanied by volcanic conglomeratic section (that include copper mineralized cobbles) and mineralized veins as the natural cause of pollution. Also distribution of Cu had been affected by the human activities such as historical and artisanal mining works. Fe contamination in the area is attributed to the alteration of andesitic rocks.}, keywords = {Chah Morra,Stream Sediment,Litho-geochemistry,Heavy Minerals,Cu mineralization,pollution}, url = {https://jtethys.journals.pnu.ac.ir/article_2827.html}, eprint = {https://jtethys.journals.pnu.ac.ir/article_2827_f1f954db0f8af7e4e88ef84ff2148be9.pdf} } @article { author = {}, title = {Integrated use of multispectral remote sensing and GIS for primary gold favorability mapping in Lahroud Region (NW Iran)}, journal = {Quarterly Journal of Tethys}, volume = {2}, number = {3}, pages = {228-241}, year = {2014}, publisher = {Payame Noor University}, issn = {2476-7190}, eissn = {2345-2471}, doi = {}, abstract = {In this study, the reliability of the primary gold mineralization exploration using multispectral ETM+ imagery was investigated in Lahroud region, northwest Iran, which was conducted by integration of alteration and structural indicators. Co-occurrence of the clay minerals and iron oxides is an important criterion in gold deposit exploration; therefore, their alteration zones were mapped using Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data analysis by feature oriented component analysis (FPCS) and band ratio techniques considering their applicability and simplicity. The structural data layers including lithological units and faults maps were also utilized to enhance the accuracy of the results. The gold favorability map of the study area was then created by the combination of the aforementioned resultant alteration and structural data layers in ArcGIS based on the weights assigned by the analytic hierarchy process method (AHP) considering the main role of the alteration zones in gold mineralization exploration. The final primary gold favorability map was evaluated through the known Au indices and ore bodies in the study area. Quantitative assessment of the results was carried out by means of the frequency ratio coefficient (FRC) that normalizes the total number of Au signatures in each potential zone with the relevant area measurement. Approximately 16% of the study area was categorized as the most favorable zone for primary gold mineralization which involves 50% of the Au signatures. Accordingly, the high potential zone which represents the highest FRC value (3.14) confirms the efficiency and reliability of the applied procedure. Therefore, the application of multispectral remote sensing techniques alongside the structural analysis is a reliable, rapid and cost effective method for mineral exploration.}, keywords = {Alteration mineral mapping,ETM+,GIS,Multispectral data analysis,Analytic hierarchy process, Primary gold mineralization, Lahroud}, url = {https://jtethys.journals.pnu.ac.ir/article_2828.html}, eprint = {https://jtethys.journals.pnu.ac.ir/article_2828_8bee7ce24512b81f5951edc203bead7c.pdf} } @article { author = {}, title = {Application of AVO Attributes and Fluid Replacement in Determining AVO Anomaly; Case Study of Aboozar Oil Field, Iran}, journal = {Quarterly Journal of Tethys}, volume = {2}, number = {3}, pages = {242-253}, year = {2014}, publisher = {Payame Noor University}, issn = {2476-7190}, eissn = {2345-2471}, doi = {}, abstract = {AVO analysis is a technique which is widely used in industry and is applied on seismic prestack data. Results from changes in seismic wave reflection amplitude versus offset can be used in extracting elastic properties and hence lithology and reservoirs pore fluid identification. Before performing AVO analysis studies, processing steps should be ensured that changes in reflection amplitude are relative to only changes in elastic properties of layers. One of the major parts of AVO analysis is investigation of common AVO attributes such as AVO intercept, AVO gradient and scaled Poisson’s ratio and their combinations. The crossplot of AVO attributes can play an efficient role in AVO analysis. In this research, AVO analysis is executed on a loose and unconsolidated sandstone reservoir and also well logging data were used to calibrate real seismic data. By using Fluid Replacement Modeling (FRM) and Gassmann’s equation on reservoir well data, AVO behavior in every conditions of reservoir (with changes in fluid type and saturation) shows that it belongs to class IV of Rutherford and William’s classification. Moreover, hydrocarbon zones which are defined using applying AVO attributes on cross-sections and target horizon, are found consistent with information from well data.}, keywords = {modeling,Fluid Replacement Modeling,Amplitude versus Offset,AVO Attributes,AVO Attributes Cross Plots}, url = {https://jtethys.journals.pnu.ac.ir/article_2829.html}, eprint = {https://jtethys.journals.pnu.ac.ir/article_2829_c9a2a97f553dcf9874f7f831468bc8bf.pdf} } @article { author = {}, title = {Slope Instability Assessment using a weighted overlay mapping method, A case study of Khorramabad- Doroud railway track, W Iran}, journal = {Quarterly Journal of Tethys}, volume = {2}, number = {3}, pages = {254-271}, year = {2014}, publisher = {Payame Noor University}, issn = {2476-7190}, eissn = {2345-2471}, doi = {}, abstract = {Every year, a considerable portion of the national budget specifies to reconstruct the properties which have been destroyed during natural disasters in Iran. Recognition of vulnerable sites to natural disasters can reduce the probable damages. The most important point in designing railway tracks is to join stations in the least possible time. So, the railway track is meant to cross lots of valleys, mountains and hilly areas. In order to insure the safety of lives and properties that are going to use the railway track, a supplementary study of landslide and rock fall susceptible areas is vitally important. Six factors of slope angle, morphology, material's fabric (lithology), vegetation cover, hydrological condition and faults and fractures activities, were recognized as major factors in occurrence of a landslides in the Khorramabad - Doroud railway track. Spatial data of these factors were collected from satellite remote sensing imageries, 1:100,000 geological maps and 1:100,000 topographical map sheets and also field investigations. After production of thematic data layers, they were resampled by the cell size of 250 meters. In this GIS based overlay mapping approach, According to the influence to landslides, the Data layers were arranged in a hierarchy order from 1 to 6, where the bigger number, shows higher susceptibility to mass movements. Based on computed Landslide indexes, the area was classified into five different classes of instability including, critical, highly unstable, moderately unstable, moderately stable and stable zone. To facilitate the validation, statistical analyses and field investigations were performed. Results showed a significant relationship between susceptibility classes and recorded mass movements.}, keywords = {Slope Instability,Remote sensing,GIS,Khorramabad-Doroud Railway Track,Landslide Susceptibility}, url = {https://jtethys.journals.pnu.ac.ir/article_2830.html}, eprint = {https://jtethys.journals.pnu.ac.ir/article_2830_4b71b9e018991cce32d46dbc9ecd1c19.pdf} }