M. R. Kebria-ee
Abstract
Geirud Formation has a wide distribution in the Damghan region. The Formation Lithology is mostly composed of limestone, marly limestone, shale and quartizic sandstone and its thickness ranges from 10 - 200 meters. Brachiopoda of Geirud Formation in the southwest, north and northeast of Damghan region ...
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Geirud Formation has a wide distribution in the Damghan region. The Formation Lithology is mostly composed of limestone, marly limestone, shale and quartizic sandstone and its thickness ranges from 10 - 200 meters. Brachiopoda of Geirud Formation in the southwest, north and northeast of Damghan region (Darvar, Simeh- Kuh and Deh- Molla sections) were studied and resulted in recognizing some species that are as follows: Schellwienella sp., Mesoplica sp., Sentosia sp., Schizophoria impressa, Leptagonia sp., Aulacella interlineata, Zaigunrostrum iranicum, Leptocaryorhynchus jamensis, Araratella dichotomians assimulata, Araratella sp., Centrorhynchus charakensis, Megalopterorhynchus chanakchiensis, Paurogastroderhynchus nalivkini, Paurogastroderhynchus bikniensis, Cleiothyridina coloradensis, Cleiothyridina sp., Athyris tau, Composita cf. globosa,Lamellosathyris sp., Cyrtospirifer sergunkovae, Cyrtospirifer sp.,Cyrtiopsis graciosa chakhaensis, Cyrtiopsis lapparenti, Prospira struniana, Prospira lapparenti, Rigauxia cyrtinaeformis, Rigauxia crassiplicatus, Dichospirifer thylakistoides, Eobrachythyris sp.,Toryniferella echinulata, Cryptonella sp. Based on the above mentioned Brachiopoda an age of Early Famennian- Late Famennian can be considered for carbonate part of Geirud Formation in the these sections. Also, Geirud Formation in the sections is equivalent with middle and upper parts (with the exception of Rossirhynchusbiozone) of Geirud Formation in the type section (Central Alborz).
M Foudazi; H Sheikhi Karizaki; M Qholipour
Abstract
The outcropped intrusive bodies in NW of Takestan show a combination of granite, granodiorite, tonalite, monzodiorite, quartz syenite, quartz monzodiorite, monzonite, quartz monzonite, and diorite. The granitoids rocks are calc-alkaline, high-K calc-alkaline, shoshonite, and metaluminous in character. ...
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The outcropped intrusive bodies in NW of Takestan show a combination of granite, granodiorite, tonalite, monzodiorite, quartz syenite, quartz monzodiorite, monzonite, quartz monzonite, and diorite. The granitoids rocks are calc-alkaline, high-K calc-alkaline, shoshonite, and metaluminous in character. The shoshonite characteristics of these rocks are caused by deformations created by the effect of penetration of hydrothermal solutions, which also increased some of the mobile elements such as potassium. The tectonic environment of these granitoid bodies are determined based on the geochemistry of main elements as collision (of Late Orogenic) and post collision uplift as well as collision (IAG+CAG+CCG) and based on the geochemistry of REE as volcanic arc granitoids, and collision granitoids (VAG+SYN+COLG) specially post collision granitoids. The chondrite normalized spider diagram of granitoid rocks of NW Takestan including samples having intermediate to acidic compositions, are enriched by LREE such as La, Ce, Pr to HREE such as Tm, Yb, Lu. Negative anomaly of Eu shows not only governing of the restoration of the terms in magma, but also display the entrance of the double capacity of this element in feldspar structure especially plagioclase. The normalized pattern of these granitoids with ORG shows their enrichment of LILE specially K, Rb, and Ba against HFSE (Nb & Zr) and HREE such as Y, Yb. This pattern is similar to the granitoid patterns, which are formed by the volcanic arc granitoids (VAG).
Petroleum geology
Bita Arbab; Davood Jahani; Bahram Movahed
Abstract
The Aptian Shuaiba deposits, in southeastern of Persian Gulf due to having resistivity less than 6 to 1 ohm.m, is considered as low resistivity pay zone. On the basis of experimental studies 8 microfacies defined which settled in a carbonate platform of homoclinal ramp model that belong to outer, ...
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The Aptian Shuaiba deposits, in southeastern of Persian Gulf due to having resistivity less than 6 to 1 ohm.m, is considered as low resistivity pay zone. On the basis of experimental studies 8 microfacies defined which settled in a carbonate platform of homoclinal ramp model that belong to outer, middle, inner ramp. Existence micro porosity in the microfacies is main reason for lowering resistivity. Various digenetic process are seen such as micritization and pyritization which have noticeable impact on declining resistivity. Lønøy method applied to address pore throat sizes which contain Intercrystalline porosity, Chalky limestone, Mudstone micro porosity. Pore systems are at class 3 Lucia. NMR logs and core data have been used for defining reliable water saturation and reservoir characterization. Results explain that decreasing of resistivity in pay zone is related to texture and grain size variation not being existence of moved water .Irreducible water estimate for this reservoir between 30 to 50 %.
Gh. Ghorbani Rostam; M. Pakzad Pakzad; N. Mirzaei
Abstract
There are two different seismotectonic zones in around of the Zendan- Minab- Palami (ZMP) fault system and the Oman Line, in south of Iran (Makran subduction zone in the east and Zagros collision zone in the west), which led to the complexity of this region. Since studying the stress field is important ...
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There are two different seismotectonic zones in around of the Zendan- Minab- Palami (ZMP) fault system and the Oman Line, in south of Iran (Makran subduction zone in the east and Zagros collision zone in the west), which led to the complexity of this region. Since studying the stress field is important for accurate perception from elastic features of environment, surveying the exerted the tectonic stresses to the tectonics plates and their magnitude, and description the geodynamic of this region, in this study considerd to assessment of stress field and also, maximum horizontal stress (SH) in around of ZMP fault system. To receive this purpose, amount and direction of stress is calculated by iterative joint inversion of earthquake focal mechanism. From east to west of ZMP fault system, with transition from Makran subduction to Zagros collision, direction of SH is reduced from 5.09º in east to 0.9º. To surveying the strain field, we used Global Positioning System (GPS) data. Maximum variance between velocity vector and direction of SH is determined in Bandar-Abbas (BABS) station, that located in adjacent of ZMP fault system. The friction coefficients which obtained in this study show that friction in Makran zone is more than Zagros zone.
somaye kazemi koohbanani; seyed jamal sheikh zakariai; mohammad hashem emami; Rahim Dabiri
Abstract
KoheSiah volcanic complex is in north east of Qorveh in the Kurdistan province and in Sanandaj-Sirjan zone.The age of the studied region rocks are related to the quaternary time. Set volcanic cone with a crater that has been identified as unspecified and are an average height of 2157 meters above sea ...
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KoheSiah volcanic complex is in north east of Qorveh in the Kurdistan province and in Sanandaj-Sirjan zone.The age of the studied region rocks are related to the quaternary time. Set volcanic cone with a crater that has been identified as unspecified and are an average height of 2157 meters above sea level. The composition of volcanic rocks varies from basaltic composition, Basalitic andesites, andesite and , trachyandesite. On the basis of mineral chemistry the amphiboles are classified as calcic (magnesio-hornblende). Plagioclases vary from andesine-oligoclase to labradorite. Al-barometer accounts that the pressure of amphibole crystallization is 3.2 to 6.65 Kbar and Altotal versus Fetotal/(Mg+Fetotal) accounts the pressure between 4.5 to 7 Kbar. Hornblende - plagioclase thermometer shows 464 to 473 °C for equilibrium of these two minerals and biotite thermometer shows 500 to 650 °C for biotite in andesites. The estimated oxygen fugacity imply an oxidation magma (confirms iron oxide and enrichment of Mg in amphibole)
A. Saki; A. A. Baharifar
Abstract
Field relations and petrographical features, shows that formation of the metapelitic and carbonate rocks of Hamadan in Western Iran was poly-metamorphic. The intrusion of the Alvand Batholite (Jurassic age) into pelitic and calcareous host rocks has produced metamorphic rocks in the Cheshin area containing, ...
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Field relations and petrographical features, shows that formation of the metapelitic and carbonate rocks of Hamadan in Western Iran was poly-metamorphic. The intrusion of the Alvand Batholite (Jurassic age) into pelitic and calcareous host rocks has produced metamorphic rocks in the Cheshin area containing, sillimanite hornfels, marbles and calc-silicate rocks. Mineral assemblages in the metapelitic and calc-silicate rocks are different, peak metamorphic assemblages of these rocks respectively are garnet, biotite, staurolite, aluminosilicate minerals (kyanite/sillimanite), muscovite and quartz but calc-silicate assemblage are garnet, diopside, wollastonite epidote and amphibole, which usually take place by contact metamorphism. Using multiple equilibria, temperature (~600-630 ºC), pressure (~2-4 kbar), and fluid composition (XCO2 as low as 0.17) have been calculated for the formation of the calc-silicated rocks. The results show good agreement with those from other meta-pelitic rocks. P-T results indicate that contact metamorphism conditions occur in pyroxene hornfels facies in this part of the Hamadan crust.
S. M. Hamidzadeh; A. Babazadeh; B. Asgari – Pirbaluti; A. Solgi
Abstract
The Asmari Formation was measured and sampeled in Ghar-e Agha Seyyed at Farsan area in order to determine sedimentary environment based on facies analysis. In the study area, the Asmari Formation has a thickness of 183 m and conformably underlained the Pabdeh Formation. Based on microfacies studies, ...
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The Asmari Formation was measured and sampeled in Ghar-e Agha Seyyed at Farsan area in order to determine sedimentary environment based on facies analysis. In the study area, the Asmari Formation has a thickness of 183 m and conformably underlained the Pabdeh Formation. Based on microfacies studies, 8 microfacies were recognized such as:1) Porcelanouse foraminifera – bioclastic – red algal wackestone / packstone, 2) Rotalia grainstone, 3) Bioclastic –red algal grainstone, 4) Red algal – coral boundstone, 5) Red algal wackestone (Floatstone), 6) Red algal –large hyaline foraminifera – intraclast packstone, 7) Red algal – bioclastic - large hyaline foraminifera wackestone / packstone, 8) Large hyaline foraminifera packstone. These microfacies represent three facies belts including Inner ramp, Middle ramp and Outer ramp. On the other hand, based on the presence of benthic foraminifera, the age of the Asmari Formation is related to Oligocene (Rupelian – Chatian).
M. Shahbazi; A. Mansourian
Abstract
Geological data are used in a variety of applications. These data have three dimensional (3D) nature and hence 3D modeling, storage, dissemination and presentation of the data not only provide a better understanding of the current situation and the relationship between different features and data layers, ...
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Geological data are used in a variety of applications. These data have three dimensional (3D) nature and hence 3D modeling, storage, dissemination and presentation of the data not only provide a better understanding of the current situation and the relationship between different features and data layers, but also increase the reliability of decisions. 3D Web Geographical Information Systems (3D Web GIS) are proper tools for managing and sharing geological data. However, current activities on developing geological Web GISs have paid less attention on 3D nature of geological data. In other words, most of the existing geological Web GISs are studied or established based on two dimensional data.
One of the important challenges for dissemination of 3D geological data in Web relates to utilization of a proper format for rendering 3D data in Web browsers. Such a format should have the capability of: 1- Conveying geological data, three dimensionally, in Web environment, 2- being displayed by Web browsers, 3- being standard and the standard to be clear for data producers in such a way data conversion to the desired format being possible, 4- conveying attribute data, and 5- providing users with the possibility of querying and analyzing data. Up to the knowledge of the authors, there is not currently any software which can disseminate 3D geological data in Web by employing a proper format respecting all of the above criteria. This paper proposes utilizing X3D, developed by Web 3D Consortium, as a standard text-based format for dissemination and rendering 3D data in Web. Although the format has not been developed for GIS purposes, in this research the applicability of that for modeling and presenting 3D geological data in 3D Web GIS is investigated.
M. Shafiee Ardestani; E. Ghasemi-Nejad; H. Vaziri Moghaddam
Abstract
In order to study the fossil contents of the Abderaz Formation for biostratigraphical purposes the 300 meters thick section was sampled at type section. The sequence is mainly made up of grey shales and marls with two units of chalky limestone in upper part. The lower contact of the formation with Aitamir ...
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In order to study the fossil contents of the Abderaz Formation for biostratigraphical purposes the 300 meters thick section was sampled at type section. The sequence is mainly made up of grey shales and marls with two units of chalky limestone in upper part. The lower contact of the formation with Aitamir Formation is disconform while the upper contact with Abtalkh is continuous. Fifty six species belonging to 16 genera were identified and four biozones were differentiated. These are: Helvetoglobotruncana helvetica (Sigal)total range Zone, 2-Marginotruncana sigali - Dicarinella primitiva (Premoli Silva and Sliter) Partial range Zone, 3- Dicarinella concavata (Sigal)interval Zone and4-Dicarinella asymetrica (Postuma)total range Zone. Based on, these an age of Turonian-early Campanian is quoted to the formation. Also it was shown that Helvetoglobotruncana helvetica, the index species for middle Turonian exists at the base of the formation while, in the samples immediately below this belonging to Aitamir Formation Rotalipora appenninica, the index for middel cenomanian was recorded. Therefore, lack of index species for late Cenomanian- early Turonian shows a gap spanning this period between the Aitamir and Abderaz Formations. This could be a result of sub Hersinian orogeny.
S. A. Hasheminejad; K. Ahmadi
Abstract
This paper aims to optimally determine petrophysical facies according to well log data. Using the automatic classification method of K-NN (K-Nearest Neighbours), petrophysical facies can be determined even though not optimally. For optimal determination of facies, the K-NN method is combined with FastICA ...
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This paper aims to optimally determine petrophysical facies according to well log data. Using the automatic classification method of K-NN (K-Nearest Neighbours), petrophysical facies can be determined even though not optimally. For optimal determination of facies, the K-NN method is combined with FastICA (Fast Independent Component Analysis) and DCT (Discrete Cosine Transform) methods. This increases the success rate of the K-NN method. It also brings about optimal determination of petrophysical facies after which modelling and description of hydrocarbon reservoirs can be done. The research is performed in two different ways: In the first approach, the FastICA method is applied to data and then classified by the K-NN method. In the second approach, FastICA and DCT methods are applied to data and then classified by the K-NN method. Finally, the success rate of classification by the K-NN method is evaluated in both approaches to optimally determine petrophysical facies. Such evaluations indicate that application of the second method to data significantly enhances the success rate of the classification by the K-NN method, thereby leading to optimal determination of petrophysical facies, which is the very aim of this study. The utilized data including sonic log (DT), gamma rays (SGR), density (FDC or RHOB), neutron porosity (CNL or NPHI), and deep induction logs (ILD), belongs to the Marun oil field in southern Iran.
Stratigraphy and Palaeontology
A. Mahanipour; Reza Afrooz
Abstract
In the present study, calcareous nannofossil biostratigraphy was investigated at the Paleocene ‒ middle Eocene interval at northeast Kazerun (Shahneshin anticline). A thickness of 50 m from the upper part of Gurpi ‒ lower part of Pabdeh formations is investigated and mainly consists of marly limestone, ...
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In the present study, calcareous nannofossil biostratigraphy was investigated at the Paleocene ‒ middle Eocene interval at northeast Kazerun (Shahneshin anticline). A thickness of 50 m from the upper part of Gurpi ‒ lower part of Pabdeh formations is investigated and mainly consists of marly limestone, marly shale and marl. 180 species from 31 geneus of calcareous nannofossils are identified. According to the index calcareous nannofossils and based on Agnini et al. zonation, zone CNP3 to CNP11 and zone CNE1 to CNE8 are identified at the Paleocene and Eocene interval, respectively. These biozones corresponds with zone NP3 to NP9 (in Paleocene) and NP10 to NP14 (in Eocene), based on Martini zonation. Regarding calcareous nannofossil assemblages and biozones, the Paleocene ‒ Eocene boundary is located between CNP11/NP9 and CNE1/NP10 zones, where the top of Fasciculithus richardii group is recorded. The extinction of Fasciculithus is recorded at 23 m by the last occurrence of Fasciculithus tympaniformis, which is considered as an index for early Eocene. The appearance of some species, such as Rhomboaster spp., Tribrachiatus bramlettei and assymetrical species of Discoaster araneus is recorded at the Paleocene ‒ Eocene boundary similar to other parts of the world.
S Peyravi; R Zahiri; K Moradi Harsini; H Shayesteh Azimian
Abstract
The Eocene-Oligocene zeolitic tuff sequences in the Aftarregion is located at northwestern side of the Aftar village in 32 km northwestwards of the SemnanCity. The studies of mineralogy and geology performed based on the results of the X-Ray data (XRD), chemical analysis (XRF), and the thin sections ...
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The Eocene-Oligocene zeolitic tuff sequences in the Aftarregion is located at northwestern side of the Aftar village in 32 km northwestwards of the SemnanCity. The studies of mineralogy and geology performed based on the results of the X-Ray data (XRD), chemical analysis (XRF), and the thin sections of taken samples showed 3 important units related to the process of the Aftar zeolites formation including green to brown marl, green tuffs, and Zeolite layer. Most of the known zeolite minerals in the area are clinoptilolite and heulandite and paragenesis minerals in tuffy and marly layers arecalcite, orthoclase, plagioclase, quartz, clay minerals, biotite and volcanic glass.Based on the geological and mineralogical evidences the formation of zeolite derived from the acidic magma of the volcanic eruptions in a shallow sea environment with high pH.The evidences show that increasing the pH in the tuff sedimentation environment, accommodated suitable conditions for conversion of the volcanic glass into the zeolites.
Stratigraphy and Palaeontology
Maryam Eftekhari; Azam Mahanipour; Mohammad Dastanpour
Abstract
Abstract Barremian sediments of the Garau Formation have been investigated at the southwest of the Kabir-kuh anticline (Qaleh-Darreh section) with regard to calcareous nannofossils. According to the presence of index calcareous nannofossils, NC5 biozone and NC5c, NC5d and NC5e subzones of Roth (1978) ...
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Abstract Barremian sediments of the Garau Formation have been investigated at the southwest of the Kabir-kuh anticline (Qaleh-Darreh section) with regard to calcareous nannofossils. According to the presence of index calcareous nannofossils, NC5 biozone and NC5c, NC5d and NC5e subzones of Roth (1978) and CC5-CC6 biozones of Sissingh (1977) have been identified. At the studied interval, warm water taxa like Cyclagelosphaera margerelii, Diazomatolithus lehmanii, Lithraphidites carniolensis, Micrantholithus spp., Nannoconus spp., Rhagodiscus asper and Watznaueria spp. have been recorded along with cool water taxa such as Biscutum constans, Helenea chiastia and Zeugrhabdotus embergeri. The abundance of warm water taxa is higher than cool water taxa and a reverse trend can be observed between them. Regarding cool and warm water taxa three warming phases and two cooling phases are identified which includes the warming event of early Early Barremian, cooling event of Early Barremian, warming event of Mid-Barremian, cooling event of late Barremian and warming event of Barremian-Aptian boundary. It must be mentioned that these data are in accord with other parts of the world in the Tethyan (e.g., Italy) and the Boreal realms (e.g., NW Germany and NE England). Keywords: Barremian, Biostratigraphy, Paleoecology, Garau Formation, Calcareous nannofossils.
M. Mohammady; H.R. Morady; S. Feiz nia; H.R. Pourghasemi
Abstract
Destruction and inordinate use of resources causes instability of natural slopes. Policymakers pay high attention to slopes instability investigation in order to supply zoning map to identify susceptible areas and stable location for the development of new settlements in the future. Iran especially in ...
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Destruction and inordinate use of resources causes instability of natural slopes. Policymakers pay high attention to slopes instability investigation in order to supply zoning map to identify susceptible areas and stable location for the development of new settlements in the future. Iran especially in the north and Haraz road is always exposed to landslides hazard because of climatic and physiographic conditions. In order to prepare landslide susceptibility mapping, at first, landslide distribution map and the map of effective factors were supplied by field study. Then prioritization of effective factors was carried out using AHP method and seven factors were selected as most effective factor. Then landslide hazard zoning carried out using information value and AHP models. Results showed that Shemshak formation, fluvial terraces, distance of 500 meters from road, distance of 400 meters from drainage network, the west dip direction, slope of 15-50 percents, elevation of 1500-2100 meters, residential and agriculture-garden landuse have the highest landslide susceptibility.
Sh. Shahabi; H. Shafaii Moghadam; Gh. Ghorbani
Abstract
The Ghoshchi granitic rocks are located in at north of Uromiyeh city and are mainly composed of alkali-feldspar granites, granites and aplitic dykes. These samples belong to calc-alkaline to shoshonitic series and show Fe enrichment and are classified as A-type granites. Ghoshchi granites have high K2O+Na2O, ...
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The Ghoshchi granitic rocks are located in at north of Uromiyeh city and are mainly composed of alkali-feldspar granites, granites and aplitic dykes. These samples belong to calc-alkaline to shoshonitic series and show Fe enrichment and are classified as A-type granites. Ghoshchi granites have high K2O+Na2O, FeO/MgO, Gl/Al, Ce/Nb, Zr, Y/Nb, and low CaO, Ba, Sr and Eu and are A2-type granites. Geochemical and Sr-Nd isotopes evidences suggest that these rocks were generated by highly fractional crystallization of a parental magma (melts), was derived from an enriched mantle source, which have undergone contamination by crustal materials and formed in post-collisional extentional environments in a within-plate setting. The crystallization age of these rocks, according to biotite 40Ar-39Ar and Rb-Sr dating is 262±26 Ma and 256±20 Ma, as minimum age, respectively, and 320-330 Ma as crystallization age. Ghoshchi granites formed probably within extentional zones in at the late stages of Variscan tectonic events.
A. Ghaderi; A. Aghanabati; B. Hamdi; A. Saeedi
Abstract
To study the Shirgesht Formation biostratigraphy in Kalmard Horst in relation to its conodont content, the Miyugodar (Miangodar) stratigraphic section was selected which is located in southwest of Tabas city. The Shirgesht Formation in the mentioned section is mainly composed of siliciclastic rock units ...
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To study the Shirgesht Formation biostratigraphy in Kalmard Horst in relation to its conodont content, the Miyugodar (Miangodar) stratigraphic section was selected which is located in southwest of Tabas city. The Shirgesht Formation in the mentioned section is mainly composed of siliciclastic rock units and overlay unconformably on Kalmard Formation (attributed to Pre-Cambrian) and is overlain by Gachal Formation (Carboniferous). Thirty five rock samples were selected from appropriate rock units (Shirgesht and Gachal Formation). Samples were studied in laboratory for more details. According to the extracted conodont from Shirgesht Formation in Miyugodar section, the age of this formation can be regarded as Early Ordovician (Tremadocian – Arenigian). Three conodont assemblage zones were recognized in Early Ordovician units. They are: Cordylodus spp., Deltifer and Proteus Global Standard Conodont biozones. The recognized biozones are as followed:
1- Oneotodus - Drepanodus Assemblage Zone
2- Acodus deltatus - Protopanderodus Assemblage Zone
3- Acodus - Oistodus Assemblage Zone
Exploration and Mining
V. Joudaki; F. Koohiyan-Afzal; A. Aalianvari; R. Ajalloeian; A. Sohrabi-Bidar
Abstract
Part 4 of Ghomroud tunnel is located in the Sanandaj-Sirjan geological zone. In this area, due to the existence of numerous faults, crushed zones and significant development of major and minor catchments, the tunnel has been encountered with the risk of groundwater influx. On the other hand, due to some ...
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Part 4 of Ghomroud tunnel is located in the Sanandaj-Sirjan geological zone. In this area, due to the existence of numerous faults, crushed zones and significant development of major and minor catchments, the tunnel has been encountered with the risk of groundwater influx. On the other hand, due to some limitations such as thick(up to 600 meters in some localities)overburden over the tunnel and the lack of exploratory drilling down to the tunnel level, it has been difficult to forecast and estimate the groundwater flow in the tunnel route. Due to the existence of numerous faults in part 4 of the Ghomroud tunnel ,encountering of the drilling machine (Double Shield TBM) with high-pressure water could cause influx of large amounts of water into the tunnel and collapse of rock masses in the crushed zones. It hence could cause deviation of the machine and drilling stop. In this article, the lack of data from boreholes led us to try investigating the development of groundwater flow in the tunnel based on geomorphological evidence. Analytical modeling and geomorphological field survey in the area show a relative consistency between geomorphology and volume of water flowing in the tunnel excavation. Therefore, according to measurements conducted on the water entering the tunnel, about 80 liters per second of water flowed into the tunnel, which is in agreement with geomorphological studies. Results show that the study of morphology and surface features could provide useful information in order to identify more precisely the hydrogeologic conditions of the area.
M. Advay; R. Hajialioghli; M. Moazzen
Abstract
The study area is located in the Central Iran Zone, in the view of tectonic subdivisions of Iranian terrains. The main outcropping rock types are metabasites and amphibolites having Precambrian age. The amphibolites have been classified as Ep-amphibolite, normal amphibolite, Grt-amphibolite and Grt-Cpx ...
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The study area is located in the Central Iran Zone, in the view of tectonic subdivisions of Iranian terrains. The main outcropping rock types are metabasites and amphibolites having Precambrian age. The amphibolites have been classified as Ep-amphibolite, normal amphibolite, Grt-amphibolite and Grt-Cpx amphibolite, considering characteristic mineral assemblages. The main textures are granoblastic and porphyrogranobastic. Mineral chemistry of Grt-Cpx amphibolites have been investigated in this contribution. The results have been used to estimate metamorphic P-T conditions. The compositions of amphiboles are pargasite and hornblende. Clinopyroxne is diopside. Plagioclases are rich in An content (An73.50-95.90) and Ab content is low (Ab3.90-24.70). Garnet have compositions as Alm (%45.90-%59.10)، Prp (%5.6-%16.1)، Sps (%10.90-%23.50)، GAU (%13.20-%23.70) . Garnet composition is non-uniform as increasing of Fe and Mg contents where Mn and Ca contents are decreased from the core to the rim. The peak metamorphic T-P obtained as 670 oC to 705 oC at 8.5 Kbar respectively. The estimated pressure is consistent with the depth of ~25Km correspending to the lower crustal condition. The recorded mid P-T conditions of Grt-Cpx ampgibolites belonge to Barrovian type regional metamorphism. On the basis of geological and petrological studies from the SE Qarehaghaj and the analogies with comparable rocks from adjucent Precambrian terrains, it seems that the Pan-African Orogeny is the phase causing metamorphism and consolidation of the basement rocks. The Precambrian metabasites and amphibolites have been probably formed in this regard. The subsequent mid P-T metamorphism of the metabasites under upper amphibolite facies (Barrovian type metamorphism) have been most likely recorded related to continental collision between the Arabian plate and the Central Iranian micocontinent correspending to the Alpian Orogeny during Cenozoic.
P. Garaei; K. Soleimani; S.R. Mousavi; A. Kavian
Abstract
In basins of the northern part of Iran, combination of natural and human factors has intensified landslide and related numerous damages. The investigation importance of this phenomena and effective factors of landslide occurrence and also determining susceptible zones it order to preventing and avoiding ...
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In basins of the northern part of Iran, combination of natural and human factors has intensified landslide and related numerous damages. The investigation importance of this phenomena and effective factors of landslide occurrence and also determining susceptible zones it order to preventing and avoiding its effects is required. At the beginning, of this research after field investigation, review of previous works in similar Lajemrood basin and using questionnaire, were recognized primary effective factors on landslide occurrence. Thin preparing effective factors maps in Geographic Information System. In order to quantifying the factors and weighting them, landslides percentage in different units was determined. For statistical analysis of multiple regressions the stepwise method was used which concluded with ignoring the elevation factor as regional model. Finally, geology, land use, slopes and distance from the road has the most effects on landslides. For evaluation of the accuracy of this model, neighboring basing (Varakee basin) with similar characteristics was chosen. The results have indicated that the most recorded area landslides in Varaki basin occurred in high and high hazard zonation. Thus, it can be concluded that presented model can be used for the study area.
Tectonics
ahmad lashgari; magmodreza Hayhat; mohammd mahdi khatib; Mahdi Najafi; Jaume Verges
Abstract
Determining the geometry and folding mechanism in Dezful embayment in the southwest of Iran due to the inclusion of a large amount of Iran's hydrocarbon reserves, also its role in the process of structural evolution of Zagros fold- belt, is important. In present study, structural evolution of Jarik anticline ...
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Determining the geometry and folding mechanism in Dezful embayment in the southwest of Iran due to the inclusion of a large amount of Iran's hydrocarbon reserves, also its role in the process of structural evolution of Zagros fold- belt, is important. In present study, structural evolution of Jarik anticline in the northwest of Dezful embayment have been studied based on 3D seismic data, drilling data that has been provided National Iranian Oil Company remote sensing, and the field observations. According to the provided structural cross sections, geometric variations of Jarik anticline across and along the anticline axis, has been investigated. Gachsaran formation as an upper detachment horizon, causes geometric and structural changes along the anticline axis. It seems that, in the nose of anticline, occurred the detachment folding mechanism associated with concentric geometry. And in the middle section of the anticline,that folding process is more advanced, faulted detachment folding mechanism has acted.
M. R. Esmaeilbeig
Abstract
The study of planktonic foraminifera of the Gurpi Formation at Kuh-e Khane Kat (east of Shiraz) led me to find standard biozones from Early Santonian to Middle Campaninan. Four biozones were determined: biozones I (Dicarinella asymetrica zone) and II (Rosita fornicata zone) belong to Early and Late Santonian. ...
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The study of planktonic foraminifera of the Gurpi Formation at Kuh-e Khane Kat (east of Shiraz) led me to find standard biozones from Early Santonian to Middle Campaninan. Four biozones were determined: biozones I (Dicarinella asymetrica zone) and II (Rosita fornicata zone) belong to Early and Late Santonian. Biozones III (Globotruncanita stuartiformis zone) and IV (Globotruncana ventricosa zone) represent the Early and Middle Campaninan. Due to a decrease in water depth in Kuh-e Khane Kat, Globotruncanita calcarata zone and other Maastrichtian plagic biozones were not recognized. In this section, Gurpi Formation is 220.5 meters thick and contains shale and argillaceous limestone. Its underlying and overlying formations are Sarvak and Tarbur.
P. Tahmasbi; A. Hezarkhani
Abstract
In the present research, comparative evaluation of various learning algorithms in neural network modeling was performed for ore grade estimation in Sonjail porphyry copper deposit. The main goal of the following investigation would be optimizing the network architecture and to present an architectural ...
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In the present research, comparative evaluation of various learning algorithms in neural network modeling was performed for ore grade estimation in Sonjail porphyry copper deposit. The main goal of the following investigation would be optimizing the network architecture and to present an architectural optimization trend to better performing the copper grade estimation within the region. Therefore, 12 algorithms were investigated back propagation learning algorithms. Based on this research it is merged that by applying the LM and BFG algorithms, there would be the best performance. The reasons why the other algorithms have the same performance would be presented within the paper as well. The input parameters are coordinates and the outputs are the copper grades for each specified point. To obtain the optimal structure, a network with different layers has been applied, which it has acquired 12 neurons within one layer. To investigate the data normal shapes, various normal shape has been acquired in the [0 1], which could merged the best results. Finally to get the best network optimizations several transfer functions have been applied, and the sigmoid transfer function illustrated least error when the transfer function is selected. Considering the optimal conditions, the R2 value has merged 0.946 for network which could be the result showing that the optimal network architecture causes estimation improvement.
E. Asadi Mehmandosti; B. Alizadeh; M. H. Adabi
Abstract
Marun Oilfield is one of the main Iranian Oilfield in Dezful Embayment, Zagros area which was studied geochemically in this paper. Forty three samples from different source and reservoir rocks include Garue, Gadvan, Dariyan, Kazhdumi, Sarvak, Gurpi and Pabdeh formations from different oil wells were ...
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Marun Oilfield is one of the main Iranian Oilfield in Dezful Embayment, Zagros area which was studied geochemically in this paper. Forty three samples from different source and reservoir rocks include Garue, Gadvan, Dariyan, Kazhdumi, Sarvak, Gurpi and Pabdeh formations from different oil wells were analyzed by Rock Eval VI. In addition, 23 selected extract bitumens and 6 crude oils of Bangestan and Khami reservoirs were studied by Liquid Chromatography and Gas Chromatography to compare with each other. Rock Eval data showed that Kazhdumi and Pabdeh formations with average TOC of 4.13 wt% and more than 12 mg HC/g rock amount of S2 had high hydrocarbon potential regard to other samples. HI vs. Tmax and S2 vs. TOC diagrams indicated that the Type II kerogen was the main type of kerogen in studied samples. Furthermore, Garue, Gadvan and Kazhdumi samples have high thermal maturity in compare with other samples. Also, variations of PI and Tmax versus depth indicate that Pabdeh and Gurpi samples had less thermal maturity in compare with Kazhdumi and Garue samples. Chromatograms study and variation of Pr/nC17 and Ph/nC18 indicate that studied samples have no or little evidence of biodegradation and crude oils of Bangestane and Khami reservoirs was formed in anoxic environment from the source rock with type II kerogen.
S. Khoshjavan; B. Rezai; A. Amini
Abstract
In this research, characterization studies of sedimentary phosphate rock from Zanjan Dalir area with respect to processing are investigated. According to mineralogical studies, phosphate ore (Collophane 28.13%), sedimentary mineral and the predominant constituents of the gangues were Calcite (43.53%), ...
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In this research, characterization studies of sedimentary phosphate rock from Zanjan Dalir area with respect to processing are investigated. According to mineralogical studies, phosphate ore (Collophane 28.13%), sedimentary mineral and the predominant constituents of the gangues were Calcite (43.53%), Quartz and Dolomite (4.65%). Main composition of phosphate rock were P2O5 (11.9% wt), CaO (36.36% wt), SiO2 (24.49% wt) and MgO (1.01% wt). Microscopic studies showed that apatite pletts had inclusions of Calcite and Quartz (about 15-70 microns). Content of inclusions was considerable. Mineralogy texture is very complicated. Liberation degree determined by grain counting (with optic microscope) and sink and float test methods. From The results of liberation degree studies can be inferred that in dimension about 140 microns about 96% of phosphate particles librated. In desliming step about 8.2% of total phosphate was removed. Optimum grinding time to reaching liberation of phosphate particles was obtained about 10 min and 30 second. Organic material determined by heating method (about 1.66% wt). Scanning electron microscopy studies showed that inclusions and organic materials existed. Specific gravity of phosphate particles and gangues difference was low. Based on the mentioned studies, effective method for processing of phosphate minerals from carbonate and silicate impurities is suggested flotation method.
Tectonics
mohammadreza sheikholeslami; Shirin Elyasi; Mohamad Reza Ghasemi
Abstract
The Mohr circle is a well-known method for two-dimensional strain analysis. Due to the formation of the boudins during two stages of the progressive deformation (D1 and D4) in cherty marbles, from north Golpaygan metamorphic complex, they have been analyzed for strain in two-dimension. This analysis ...
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The Mohr circle is a well-known method for two-dimensional strain analysis. Due to the formation of the boudins during two stages of the progressive deformation (D1 and D4) in cherty marbles, from north Golpaygan metamorphic complex, they have been analyzed for strain in two-dimension. This analysis is based on estimating of the initial length of the boudins before deformation, and measuring the current length of the boudins, after deformation. Calculation of the longitudinal parameters of the strain and drawing Mohr circles show that the strain ratio varies between 1.06 to 2.35 for D1 stage, and between 1.10 to 2.84 for D4 stage. The mean shear angle for the D1 stage is 22 ° and for the D4 stage is 24 °.
