N Etemad-Saeed; M. H Adabi; A. Sadeghi; M. Hosseini- Barzi
Abstract
This work is focused on tectonic provenance of the Late Neoproterozoic Kahar Formation in the northern Iran. KaharMountain (type locality) provides valuable information on tectonic events during this time. The Kahar Formation in this area is a well preserved sedimentary sequence and consists of about ...
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This work is focused on tectonic provenance of the Late Neoproterozoic Kahar Formation in the northern Iran. KaharMountain (type locality) provides valuable information on tectonic events during this time. The Kahar Formation in this area is a well preserved sedimentary sequence and consists of about 1000 meters of predominantly fine grained siliciclastic rocks and minor sandstones, conglomerates and dolomitized stromatolites. Kahar lithic arkose sandstones with low compositional and textural maturity, contain abundant feldspar (plagioclase and K feldspar), quartz, and volcanic lithic fragments and have an average composition of Q38F40L22, Qt39F40L21, Qm32F40Lt28,Qp27Lvm60Lsm13 and Qm44P33K23 suggesting a proximal source and a dissected arc setting. The type of lithic fragments in the sandstones show andesitic and felsic volcanic rock sources. Heavy mineral analysis (abundant metastable and unstable minerals such as biotite, and pyroxenes) indicate that Kahar sandstones were derived from unroofing of arc-type magmatic rocks. The low diversity of heavy mineral assemblages in the Kahar sandstones indicates that the source rocks were uniform and localized. Considering the two common tectonic views regarding the Late Neoproterozoic condition of Iran (rift-passive margin and magmatic arc-subduction zone), the results of this study which confirm the magmatic arc tectonic setting of Alborz-Iran at that time seems critical.
Z. Boroumand; E. Ghasemi- Nejad; M. R. Majidifard
Abstract
The Dalichai Formation at Talu section, 24 kilometers NE of Damghan is studied Palynologically. The Middle Jurassic sediments with a thickness of 168 meters in this section contain grey to green marl and grey marly limestone. A total of 35 samples were collected systematically and 200 palynological sildes ...
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The Dalichai Formation at Talu section, 24 kilometers NE of Damghan is studied Palynologically. The Middle Jurassic sediments with a thickness of 168 meters in this section contain grey to green marl and grey marly limestone. A total of 35 samples were collected systematically and 200 palynological sildes were prepared. Forty nine species of dinoflagellate cysts belonging to 30 genera were identified. A few fungal spores and foraminiferal test lining and spores and pollen grain were also recorded. Although, dinoflagellate species are abundant but all the species recorded were concentrated in lower parts of the section (0-110 meters). Two palynozones were identified; Cribroperidinium crispum Total Range Palynozone (Ccr), Dichadogonyaulax sellwoodii Interval palynozone (Dse). A local palynozoneof Ctenidodinium combazii/Ctenidodinium ornatum ornatum Acme Zone were also established in the succession. An age of Bajocian – Late Callovian was proposed for the succession studied.
S. Khoshjavan; B. Rezai; A. Amini
Abstract
In this research, processing of Dalir area phosphate ore was investigated for reduction of its gangue minerals such as carbonates (mainly calcite and poorly dolomite) and silicates minerals. According to characterization studies, phosphate mineral content of the ore was sedimentary collophane mineral ...
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In this research, processing of Dalir area phosphate ore was investigated for reduction of its gangue minerals such as carbonates (mainly calcite and poorly dolomite) and silicates minerals. According to characterization studies, phosphate mineral content of the ore was sedimentary collophane mineral and the predominant constituents of the gangues were calcite and quartz. Liberation degree of phosphate mineral determined by using microscopic and sink and float tests to be 140 µm. Primary flotation tests (un-pre-concentrated) results did not have desirable grade and recovery. So, at first step, phosphates samples was subjected to calcination and scrupping process. After scrupping and removing calcium and magnesium oxide, anionic and cationic flotation tests were done. By using a combination methods (calcining, scrupping and flotation) the grade and recovery of final concentrate reaches to 31% and 62% respectively. Finally a Lab-flowsheet of processing was suggested
A. Fathian Baneh; S. Solaymani Azad; H. Nazari; M. Ghorashi; M. Talebian
Abstract
Tabriz city, the most highly population city of NW Iran, is located close to the North Tabriz Fault (NTF). This 150 km right-lateral strike-slip fault consists of two major fault segments arranged in right-stepping pattern. A pull-apart basin has been formed within the overlap zone of these fault segments ...
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Tabriz city, the most highly population city of NW Iran, is located close to the North Tabriz Fault (NTF). This 150 km right-lateral strike-slip fault consists of two major fault segments arranged in right-stepping pattern. A pull-apart basin has been formed within the overlap zone of these fault segments due to the recent right-lateral motion. The basin margins mark by fault branches and fault splays, which connect these two major segments of NTF. High level historical earthquakes occurrence shows seismic activity of NTF. Among which, NTF is responsible of at least two destructive earthquakes occurred in 1721 A.D. (Ms 7.3) and 1780 A.D. (Ms 7.4). This fault has not experienced any strong seismic events since 1780 A.D. Within past decades, it has been tried to recognize large number of old earthquakes utilizing paleoseismological investigation. Previous paleoseismological studies have been focused on the NW and SE segments of the fault. In the present study, to complete the data sets necessary to assess the seismic hazard related to Tabriz city, we focus on overlap zone of the two main fault segments. Using aerial photos, satellite images and field investigations, a potential site has been recognized within the zone (6 km NW of Tabriz City) to perform paleoseismological studies. Trench opened perpendicular to fault scarp strike and focused paleoseismological investigations in that, show evidences of at least two macroseismic events.
F. ayati
Abstract
In the studied area, the Cretaceous limestone rocks with abundant cracks are located on the Jurassic shales. Skarn producer fluids have influx into these cracks from a long distance and created distal skarns. The presence of a recrystallized and skarnified limestone rock layer within the shale, distinct ...
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In the studied area, the Cretaceous limestone rocks with abundant cracks are located on the Jurassic shales. Skarn producer fluids have influx into these cracks from a long distance and created distal skarns. The presence of a recrystallized and skarnified limestone rock layer within the shale, distinct the studied skarn from the most well-known skarns in Iran and puts it in the category of reaction skarns. There are some lenses of mineral deposites within skarns which is consisting mostly of magnetite and hematite. Iron-rich solutions which are drived from intrusive rocks, have left iron as magnetite in carbonate. In addition to the formation of magnetite by hydrothermal solutions, it can also be created in retrograde step by andradite alteration. These skarn is consisting mostly of pyroxene, garnet, tremolite-actinolite, chlorite and epidote. Skarnification process has occurred in two successive stages: progressive and regressive. In progressive stage, carbonate - silicate anhydrous minerals like garnet and pyroxene have occured. At later stages, because of the atmospheric water influence, garnets are altered to epidote, magnetite, calcite and quartz and pyroxenes are altered to tremolite, actinolite, calcite, quartz and opaque minerals. There are two set of garnet in studied skarn, the first one is massive (in progressive stage) and the other one is as veinlet (in regressive stage with epidote and has been created in quartz- calcit veins along with sulfide mineralization). Garnet compositions in iron deposits of studied area lie in grossular - andradite series. The compositions of studied garnet are the same as garnet compositions in Cu-Fe skarns in worldwide.
F. Rostami; M. Delavari; S. Amini; A. Dolati
Abstract
The Permian volcanic rocks of Central Alborz (northeast of Baladeh- Siahbisheh) crop out between Ruteh and Nesen Formations. The volcanic rocks are predominantly basaltic and plagioclase- phyric. Ferromagnesian minerals such as clinopyroxene and olivine are not modally abundant and sometimes are totally ...
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The Permian volcanic rocks of Central Alborz (northeast of Baladeh- Siahbisheh) crop out between Ruteh and Nesen Formations. The volcanic rocks are predominantly basaltic and plagioclase- phyric. Ferromagnesian minerals such as clinopyroxene and olivine are not modally abundant and sometimes are totally altered. Based on microprobe data, clinopyroxene and plagioclase are diopside (En34.2-36.4 Wo43.1-47.2 Fs14.9-18.1) and labradorite (50<An%<55), respectively. Clinopyroxene and plagioclase geothermobarometric calculations shows the temperature and pressure ranges of 1050 to 1200 °C and 2 contents (4.94- 7.24 wt. %). Clinopyroxene chemical data display that the parent melt was alkaline basalt, generated in a within plate setting. On the basis of our findings it can be stated that, Central Alborz was a continental passive margin in middle- late Permian at south of Paleo-Tethys and its magmatism was likely triggered by late Paleozoic extensional tectonism of northern margin of Gondwana during the early stages of Neo-Tethyan development.
Exploration and Mining
H. Bakhshandeh Amnieh; Amirhossein Rostami; Kurosh Shahriar; Hamid Chakeri; Masoud Cheraghi Seifabad
Abstract
Abstract In the urban tunneling project, one of the most important parameters to be considered is the subsidence level. Metro tunnels are one of the most important urban transportation infrastructures. Due to shallow depth of drilling, the most important factors to prevent the maximum subsidence and ...
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Abstract In the urban tunneling project, one of the most important parameters to be considered is the subsidence level. Metro tunnels are one of the most important urban transportation infrastructures. Due to shallow depth of drilling, the most important factors to prevent the maximum subsidence and subsequent damage of surface and subsurface structures are deformation control and shear forces. The various methods of estimating the subsidence are divided in three categories, namely; Empirical, analytical and numerical methods. In this research, according to the geotechnical conditions of the study area using the data collected from the monitoring during the excavation of twin tunnels of metro by TBM, the empirical methods for the subsidence ( s=A_2+s_max/2 ), the maximum subsidence (s_max=A_1-A_2 ) and the inflection point (ⅈ=x_0 ) are presented by using Boltzmann function for Isfahan twin metro tunnel. Keywords: Subsidence, Maximum subsidence, Inflection point, Empirical Method, Analytical Method, Numerical Method, TBM.
Economic Geology
Pouria Mahmoodi; Ebrahim Rastad; Abdorrahman Rajabi; Mehran Moradpour
Abstract
The Early Cretaceous Eastern Haft-Savaran Zn-Pb (Ba) deposit situated in the Arak mining district and occurred within the extentional back-arc of Malayer-Esfahan basin. Mineralization occurred in two horizons in the Estern Haft-Savaran deposit. First horizon is major horizon that formed within the most ...
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The Early Cretaceous Eastern Haft-Savaran Zn-Pb (Ba) deposit situated in the Arak mining district and occurred within the extentional back-arc of Malayer-Esfahan basin. Mineralization occurred in two horizons in the Estern Haft-Savaran deposit. First horizon is major horizon that formed within the most upper portion of the massive limestone and second horizon occurred in the thin limestone which is alternate with shale and marl. Textures of the mineralization in this deposit are replacement, massive and vein- veinlets, and main alterations are silisification, dolomitization and calcitization. Sphalerite, galena, chalcopyrite, tetrahedryte, pyrite, bornite, chalcosite and covelite are the sulfide minerals and quartz, calcite, dolomite and sericite are gangue minerals in the ore deposit. Cathodoluminescence study in this deposit indicates three dolomites and one calcite generations. First generation of dolomite associated with weak mineralization and second generation of dolomite is Fe-rich and associated with main mineralization. Third generation of dolomite is late dolomitization and formed with calcite and cross-cutted the mineralization. Presence of framboidal pyrite with galena and sphalerite in its matrix and fine-grain euhedral barite suggest mineralization began during sedimentation and early diagenesis stage near seafloor. In continuum, main ore is identified as replacement occurrence of first generation sulfides by second generation coarse-grained sulfides under seafloor. With regarding to the formation of the Eastern Haft-Savaran deposit in the extentional tectonic setting, massive limestone as the host rock, and mineralization formation as replacment during diagenesis of the host rock under the seafloor, this deposit would be classified as Irish type deposit.
A. Bahrampour; Gh. Ghadami; H. Atapour; M. Poosti; H. Ahmadipour
Abstract
At 60km north-east of Kerman city,near Sarashk village (Ravar, Kerman province) and along the Kuhbanan fault, several lamprophyric dikes have been intruded into Carboniferous to Cretaceous sedimentary formations. Petrographically these lamprophyres could be classified into two groups: comptonites ...
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At 60km north-east of Kerman city,near Sarashk village (Ravar, Kerman province) and along the Kuhbanan fault, several lamprophyric dikes have been intruded into Carboniferous to Cretaceous sedimentary formations. Petrographically these lamprophyres could be classified into two groups: comptonites and sanaite. Olivine, clinopyroxene, plagioclase and potassium feldspar are the main minerals in all two groups. Mineral chemistry shows that olivines, clinopyroxenes and amphiboles are of chrysolite (Fo = 72.35-79.85)), augite (Wo = 44.3-50.2, En= 37.06-44.4, Fs = 9.24-14.6), and kaersutite (Ca+Na = 2), (Na+K = 0.59-0.95), (Mg/(Mg+Fe2) = 0.63-0.76) composition, respecrively. Geobarometric and geothermometric estimations along with the tectonomagmatic diagrams for clinopyroxenes show that the parental magmas werealkaline in which the clinopyroxenes crystallized at pressure of 11-15 Kbar and temperature of 1150-1300 ◦C.Whole rock chemical analyses of these rocks show that the parental alkaline magma was originated from a metasomatized lithospheric garnet- spinel- lherzolite mantle source and emplaced in a post-collisional environment.
vahid joudaki; Rasoul Ajalloeian; Jafar Hassanpour
Abstract
In massive mechanized tunneling projects, there is a need for extensive geological studies. These studies require sufficient knowledge of various fields of geology . In this research, the view of graduates of engineering geology, about educational and industrial experiences has been studied.This research ...
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In massive mechanized tunneling projects, there is a need for extensive geological studies. These studies require sufficient knowledge of various fields of geology . In this research, the view of graduates of engineering geology, about educational and industrial experiences has been studied.This research is a descriptive survey. The research population consisted of all active engineers of geology in the country. By using simple random sampling, 50 people were selected. Data were collected by a researcher-made questionnaire, and data were interpreted using descriptive statistics.The results of the survey show that in many specialized courses and in undergraduate practical units, technological applications of topics in related industries have not been addressed. From the perspective of the population of the statistical community, the current curriculum needs to be reviewed and new lessons need to be developed. The results show that a small part of the students' practical units in applied spaces are performed. According to people, in the field of postgraduate studies, a significant proportion of theses have a theoretical and fundamental aspect. On the other hand, there is no research collaboration in interdisciplinary research between geological colleges and engineering faculties (electronics, mechanics, etc.). .The results show that, in the current situation, the revision of educational topics and the wider activity of geological associations can enhance the potential of geology graduates in industrial jobs. Therefore, in this paper, with a brief overview of the conditions of geological groups and the country's mechanized drilling industry, suggestions are presented to solve the challenges.
Petrology
Seyyed Navid Seyyed Mardani; M. Moazzen; Ahmad Jahangiri
Abstract
The Muth-Golpayegan metamorphic complex is situated at north of Golpayegan city in the Isfahan province. This complex is constituted from different metamorphic rocks including variety of pelitic schists, amphibolite, gneiss, quartzite and marble. Garnet schists are dominant lithology in the area and ...
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The Muth-Golpayegan metamorphic complex is situated at north of Golpayegan city in the Isfahan province. This complex is constituted from different metamorphic rocks including variety of pelitic schists, amphibolite, gneiss, quartzite and marble. Garnet schists are dominant lithology in the area and contain different minerals, such as garnet, quartz, chlorite, muscovite, biotite, staurolite, andalusite, kyanite and sillimanite. Lepidoblastic, porphyroblastic, poikiloblastic, augen and millipede are the main textures in these rocks. The degree of metamorphism increases from SW to NE in a way that slate and phyllite at SW change gradually to chlorite schist, biotite schist, garnet schist, staurolite schist, sillimanite schist and kyanite schist. The occurrence of these schists is accompanied by appearance of chlorite, biotite, garnet, staurolite, sillimanite and kyanite mineralogical zones in the field. The succession of these zones is compatible with Barrovian regional metamorphic gradient. Chlorite, biotite and garnet zones belong to the greenschist facies and staurolite, sillimanite and kyanite zones belong to the amphibolite facies. Temperature range calculated for these rocks by garnet-biotite thermometry is 471-581 C. This metamorphic gradient is a result of continental collision.
Nasrollah Abbassi
Abstract
Cretaceous flysch deposits of the Abshar-e Asyab Kharabeh (30 meters) in west of Siah-rud village in the Jolfa area, NW Iran, consist of conglomerate, sandstone, siltstone and mud- or marlstone layers, which mainly belong to A, B, D and E divisions of Bouma sequence. A divers trace fossils preserved ...
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Cretaceous flysch deposits of the Abshar-e Asyab Kharabeh (30 meters) in west of Siah-rud village in the Jolfa area, NW Iran, consist of conglomerate, sandstone, siltstone and mud- or marlstone layers, which mainly belong to A, B, D and E divisions of Bouma sequence. A divers trace fossils preserved on the lower bedding planes of sandstones and siltstones as positive hyporelief, includes: Bergaueria hemispherica, Bergaueria isp., Cochlichnus isp., Granularia isp., Halopoa imbricate, Helminthoida crassa, Helminthopsis abeli, Imponoglyphus torquendus, Neonereites multiserialis, Paleodictyon latum, Paleodictyon cf. majus, Paleodictyon nodosum, Palaeophycus alternatus, Palaeophycus sulcatus, Phycodes templus, Phycodes isp., Planolites annularis, Planolites beverleyensis, Protovirgularia longespicata, Squamodictyon isp., Strobilorhaphe isp., Thalassinoides isp., Taphrhelminthopsis recta, Taphrhelminthopsis convolute, Treptichnus pollardi. These trace fossils are mainly grazing-feeding or feeding traces of Nereites Ichnofacies and classifiable in six rang/frequency, based ichno-assemblages. Obtained trace fossils were produced during post-event calm periods. So, muddy sediments deposited after turbulence currents and traces have been made on these layers, activates of trace makers were developing when accessible feeding materials or dissolved oxygen increased in environment. Base on founded Nereites trace fossils, these sediments deposited in the deep marine abyssal zone environment.
H.R. Vatanpour; A. Khakzad; M. Ghaderi
Abstract
Sabzevar ophiolitic belt is located in the northwest of Iran, north of Sabzevar. The current study is carried out for the first time in Iran with an exploration approach in the western part of the belt. Study of Platinum Group Elements (PGE) is of high importance for determining the genesis and economic ...
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Sabzevar ophiolitic belt is located in the northwest of Iran, north of Sabzevar. The current study is carried out for the first time in Iran with an exploration approach in the western part of the belt. Study of Platinum Group Elements (PGE) is of high importance for determining the genesis and economic evaluation of chromite deposits specifically in ophiolitic complexes. Chondrite-normalized PGE patterns of the chromitites related to ophiolites have a negative slope suggesting that during initial stages of magma crystallization, chromite preferentially removed compatible PGE from the magma. These patterns in the Sabzevar chromitites imply that these rocks are related to ophiolitic complexes (Alpine type). Chromite ore bodies which exhibit a relatively high incompatible/compatible element (Pd/Ir, Cu/Ni) ratios are derived from a more evolved magma with a lower fractional melting degree and do not seem to be of economic importance; this ratio in Al-rich chromites is higher than that of Cr-rich type. Pd/Ir ratio in Sabzevar chromitites on the average is less than 1, similar to many important chromite ore bodies related to ophiolitic complexes throughout the world. This ratio being low, as well as high chromium number (Cr/Cr+Al>0.60) suggests that this complex can be considered to contain a significant potential for economic and metallurgical chromite. Furthermore, the complex does not contain chromitites of uniform composition in chalcophile elements. PGE patterns of peridotites in the study area also show that these units in upper parts of the Gaft area are similar to ultramafic cumulates of oceanic crust, while in lower parts of Faroumad area related to mantle sequences.
Gh. A. Moafpourian; M. Pourmoafi; M. Vosoughi Abedini; M. H. Emami; M. R. Jannessari; S.w. Parman
Abstract
Scattered outcrops of ultramafic – mafic rocks and interbeded sedimentary layers in the North of Fariman – Torbat-e- Jam lineament are exposed mainly at the west of Mashhad, east of Fariman and north of Torbat-e- Jam in Agh- Darband area. Our studies on ultramafic – mafic rocks have ...
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Scattered outcrops of ultramafic – mafic rocks and interbeded sedimentary layers in the North of Fariman – Torbat-e- Jam lineament are exposed mainly at the west of Mashhad, east of Fariman and north of Torbat-e- Jam in Agh- Darband area. Our studies on ultramafic – mafic rocks have revealed several fields and petrographic evidences which demonstrate their volcanic to subvolcanic origin. Moreover, observation of various disequilibrium textures including the presence of glass, elongate and hopper pyroxene and olivine, occurring as pyroxene spinifex and olivine microspinifex textures in mafic and ultramafic rocks, can just be explained on the basis of their volcanic origin. On the basis of geochemical criteria, defined by IUGS for high MgO ultramafic and mafic volcanic rocks, these rocks are classified as komatiitic, picritic and basaltic types. Essential geochemical contrasts, including various ratios of incompatible immobile trace elements and different patterns of REE and spider diagrams, are too high to be explained on the basis of various degrees of partial melting of a uniform mantle source or AFC processes. It is thus possible to consider the role of a heterogeneous mantle source and/or dynamic melting in petrogenesis of these rocks. Furthermore to the cited heterogeneity which can be explained by mantle plume assumption, position of Fariman’s samples in the diagrams of (Nb/Th)N versus (Nb/La)N and Nb/Th versus Zr/Y which mainly plot at the OPB area, and Zr/Y versus Nb/Y which plot on or above ∆Nb line, coincide with the same assumption. Here we have argued that disequilibrium textures had been formed by undercooling of superheated melts, originated from an ascending mantle plume source, and rapid growth of crystals in such a melts. This arguement is favored with regard to high Fo contents of olivines which make necessary equilibrium of these crystals to high MgO contents and hot melts. We have estimated the MgO content and temperature of parent melt as much as 23.74% and 1470-1535ºC respectively based on maximum Fo content of olivine crystal in a komatiitic sample. These values are too high to correspond to a subduction or even a normal MORB related environments; however, similar to a hot spot tectonic setting.
Mohammad Mohajjel; Z. Rahami; F. Shabani
Abstract
Lower-red, Qom and Upper-red Formations with Pliocene conglomerates were all folded in Shurab syncline containing northwest-southeast axial trace in southeast Qom city. In the southeastern part of the northern limb of the Shurab syncline, gypsum and marl elastic units of the Qom Formation have played ...
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Lower-red, Qom and Upper-red Formations with Pliocene conglomerates were all folded in Shurab syncline containing northwest-southeast axial trace in southeast Qom city. In the southeastern part of the northern limb of the Shurab syncline, gypsum and marl elastic units of the Qom Formation have played a detachment surface role against the most competent layers of the Upper-red Formation due to high competency contrast. Rock units of the Qom Formation were thickened and locally folded with about north-northeast orientation in the southeastern part of the northern limb of the Shurab syncline. The thickening and folding in this part of the Shurab syncline is interpreted as the shearing process which has been produced in a shear zone initiated between the detachment surface and the Qom fault segment in the northern part of the Shurab syncline that was activated by right-lateral strike-slip displacement of the Qom fault in post Miocene.
F. Masoudi; M. Mohajjel; F. Shaker Ardekani
Abstract
The Zarrin area in the north of Ardekan is the part of Central Iran Zone. Some homogenous parts of Zarrin granite located in the shear zone changed to mylonites and ultramylonites. Microstructural evidence and deformation investigation show that chemical and structural changes occurred during the progressive ...
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The Zarrin area in the north of Ardekan is the part of Central Iran Zone. Some homogenous parts of Zarrin granite located in the shear zone changed to mylonites and ultramylonites. Microstructural evidence and deformation investigation show that chemical and structural changes occurred during the progressive deformation in mylonites. The most obvious chemical change is the noticeable decrease on Ti, Mg, Fe and P from mylonites to ultramylonites. Silica shows a slight increase in the mylonitic zone with progressive increase in modal quartz, but Al2O3 is nearly constant during the mylonitization. Because of decrease on feldspar porphyroclasts and feldspar grains in the matrix, compare to protomylonites, K2O decreases in mylonites. However, with relative increase on plagioclase, K-feldspar and epidote in the matrix, Ca, Na and K increase in ultramylonites. As a result of structural changes, quartz grains in weakly deformed protolith and protomylonite show recrystallization and sub grain. In a progressive deformation process, quartz in mylonites and ultramylonites reveals grain boundary migration in recrystallization. During the progressive deformation, K-feldspars become perthitic with fractures and plagioclases show kinking in their twins. With progress in deformation, recrystallization on K-felspar's margins and twins in plagioclase grains are formed. Based on structural evidence, temperature of 400ºC has been estimated for deformation in Zarrin area in protogranites and protomylonites. The temperature continuously increases up to 500ºC or more in green schist facies in the mylonites and ultramylonites.
Petroleum geology
Mohammad Javad yousefzadeh; Bijan Maleki; Mir Hassan Moosavi; parviz armani
Abstract
Investigation of probable source rocks in oil fields is very important. In this study, in addition to evaluating the hydrocarbon potential, the kinetic models of Lopatin and Arrhenius were used to more precisely assess the source rock maturity status as well as the percentage of oil generation in the ...
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Investigation of probable source rocks in oil fields is very important. In this study, in addition to evaluating the hydrocarbon potential, the kinetic models of Lopatin and Arrhenius were used to more precisely assess the source rock maturity status as well as the percentage of oil generation in the Solabdar oil field. This field is southeast of Bibi Hakima Square, located in the Dezful embayment. Possible source rocks are scorpions, scorpions, Gurpi and Pabdeh. The samples were also analyzed kinetically and the transformation ratio (TR) of kerogen to the generated hydrocarbon was determined. According to the burial history, the source rock of Kazhdomi formation has reached the highest temperature and depth compared to other source rocks. According to the results of Lopatin method, the transformation rate of organic matter in formations, Gurpi and Pabdeh was determined by 41%, 30% and 30%, respectively. This transformation rate by Arrhenius method was 47%, 15%, and 13%, respectively. This difference is due to the two-factor assumptions that the article discusses.
B. Vahdati Daneshmand; M.R. Ghassemi; M. Ghorashi; N. Haghipour
Abstract
According to historical maps of Iran, changing the course of Sepidrud from Dastak to Kiyashahr has occurred in a very recent time. Although migration of meandering streams over the delta plain is a natural phenomenon and oscillations of Caspian Sea might have affected the course ...
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According to historical maps of Iran, changing the course of Sepidrud from Dastak to Kiyashahr has occurred in a very recent time. Although migration of meandering streams over the delta plain is a natural phenomenon and oscillations of Caspian Sea might have affected the course of SepidrudRiver, the deflection of Sepidrud between Astaneh and Koochesfahan is probably related to activity of concealed structures wit
hin the delta deposits. This research uses calculation of morphotectonic indexes to study effects of active range boundary within range faults in study area on drainage pattern and river streams.
R. Elyaszadeh; M. Mohajjel; B. Farahani; S. R. Jafari
Abstract
Structural analysis of the NW-SE oriented Alborz fault in north Qom, demonstrates young left-lateral reverse displacement evidence, based on the rake of the striations on young fault planes (45-53). Strong structural evidence exists for its previous right-lateral reverse displacement. Young left-lateral ...
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Structural analysis of the NW-SE oriented Alborz fault in north Qom, demonstrates young left-lateral reverse displacement evidence, based on the rake of the striations on young fault planes (45-53). Strong structural evidence exists for its previous right-lateral reverse displacement. Young left-lateral displacement evidence in NW-SE oriented oblique and strike-slip faults recently was documented in central-west (eg. Mosha and Talegan faults) and south Alborz mountains (eg. Ipak and Kusk-e-Nosrat faults) due to the compression direction of the south Caspian oceanic crust with Alborz mountains. Replacement of right-lateral reverse mechanism by young left-lateral reverse mechanism in the Alborz fault in north Qom implies that the inversion of the central-west Alborz faults is being transferred through to the same oriented faults in south Alborz mountain up to the Qom area.
M. Esterabi - Ashtiani; A. Yassaqi; H. R. Javadi; M. Shahpasandzadeh; M. R. Ghassemi
Abstract
Dorouneh Fault is located in the north of Central Iran Microplate with left-lateral strike-slip mechanism and plays an important role in the formation of Iran plateau's morphology. Dorouneh fault, with bend geometry and 900 km length, extends from HyrmandRiver in the Afghanistan border to Anarak area ...
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Dorouneh Fault is located in the north of Central Iran Microplate with left-lateral strike-slip mechanism and plays an important role in the formation of Iran plateau's morphology. Dorouneh fault, with bend geometry and 900 km length, extends from HyrmandRiver in the Afghanistan border to Anarak area in the Central Iran. Dorouneh Fault terminates in the Jandaq area as sub-parallel branches. Towards west, general trend of Dorouneh Fault System changes from northeast-southwest to north-south in the north of Talmessi Mine. Fault branches are observed as left-lateral strike-slip faults with normal dip-slip component in the Jandaq-Talmessi area that is introduced as a trailing extensional imbricate fan. But, considering slip sense inversion along Dorouneh Fault, the main mechanism for formation of western termination before slip sense inversion is a trailing compressional imbricate fan.
M.R. Partoazar
Abstract
The stratigraphic section of Esfeh is located at 15 km north-east of Shahreza and 65 km south of Esfahan. The aim of this study is to consider the lithostratigraphy, biostratigraphy and how to settle the Permian-Triassic boundary, also the geochronology of them. The biostratigraphic study of this section ...
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The stratigraphic section of Esfeh is located at 15 km north-east of Shahreza and 65 km south of Esfahan. The aim of this study is to consider the lithostratigraphy, biostratigraphy and how to settle the Permian-Triassic boundary, also the geochronology of them. The biostratigraphic study of this section indicates the existence of index Fusulinidae with the high quality of other places. for instance:Verbeekina verbeeki , Sumatrina annae , Afghanella schenki , Yangchienia iniqua , Eoparafusulina Shengi.In this study the geochronological change of member 3 of the Surmagh Formation with attention to index fossils attributed from Guadalupian to Early Julfian and also the lithoiogical alterations to exist in deposits of the Hambast Formation equivalent to Esfeh section, the Shahreza formation propose is necessary.
A. Nejati Kalate; V. Ebrahimzadeh Ardestani; E. Shahin; S. H. Motavalli Anbaran; Sh. Ghomi; E. Javan
Abstract
Determination of the geometry of bedrock, by nonlinear inverse modeling of gravity data, is the aim of this paper. In this method, reliable geological structures can be obtained by minimum geology priori information. The usual practice of inverting gravity anomalies of two-dimensional bodies replaced ...
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Determination of the geometry of bedrock, by nonlinear inverse modeling of gravity data, is the aim of this paper. In this method, reliable geological structures can be obtained by minimum geology priori information. The usual practice of inverting gravity anomalies of two-dimensional bodies replaced by n-sides polygon for determining location of the vertical that best explain the observed anomalies. In this method, the geometry of the bedrock is replaced by a series of juxtaposing prisms. Finally the length of each prism is the depth of the bedrock at that point.
The algorithm uses a nonlinear iterative procedure for simulation of bedrock geometry. At the first step, the nonlinear problem changes to a linear problem by a proper approximation and standard method. The second step is the parameterization of the model. Finally, an initial model is suggested on the basis of geological and geophysical assumption and using the numerical analysis, Jacobean matrix is calculated. In each iteration the inversion will improve the initial model, considering the differences between observed and calculated gravity anomalies, based on Levenberg-Marquardt's method.
The practical effectiveness of this method is demonstrated by inversion of synthetic (free noise and noise contaminated data) and real examples. The real data is acquired over the Moghan area and the results compared with the geological information.
Parisa Piroozfar; Samad Alipour; Soroush Modabberi; David Cohen
Abstract
This study investigated the hydrogeochemistry and environmental water quality of rivers in Sarough watershed using the major ion chemistry and explored multivariate statistical methods for identification of processes which release the solutes in natural waters. Totally, 38 samples were collected along ...
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This study investigated the hydrogeochemistry and environmental water quality of rivers in Sarough watershed using the major ion chemistry and explored multivariate statistical methods for identification of processes which release the solutes in natural waters. Totally, 38 samples were collected along the main streams of the watershed. The mean concentrations of major cations (Na, K, Mg, Ca) and anions (Cl, NO3, CO3, HCO3, SO4) were measured about 15, 4.6, 10.5, 61, 30, 4.49, 89, 156 and 107 mg/l, respectively. The results indicated that the river waters in the Sarough watershed were neutral and fresh water in nature (mean values: pH=7.7 and TDS= 315.8 mg/l). Most of the water samples were categorized in hard and very hard water classes with mean value for TH=197 mg/l and were under-saturated regarding with major carbonates, sulfates and evaporate minerals in most of samples. The major water types were Ca–HCO3–SO4, Ca–Mg–CO3 and Ca–SO4–HCO3. The Na, Cl and NO3 concentration in all water samples fell within the accepted limit of national and international standards for drinking water. Nevertheless, Ca, Mg and SO4 content in some samples were higher than the maximum desirable limits. Schuler diagram showed that majority of the water samples were good and acceptable for drinking. Evaluating the quality of river water for irrigation purposes using Wilcox diagram and SAR, EC and RSC indices indicated that majority of the water samples were suitable for irrigation. The results of multivariate statistical techniques such as correlation coefficient matrix, CA and PCA indicated the strong association between Na-K-Cl-SO4 and Ca-Mg-CO3-TH. It was assumed that weathering of carbonates (limestone/dolomite formations, calcareous marl formation and travertine) in the area were common source of Ca, Mg and HCO3. Also, travertine springs were considered as active point sources which release these elements into the drainage system. Meanwhile, dissolution of halite and gypsum in red marl formations (lower part of Qom F. and Upper Red F.) were the main processes considered as the origin of Na, K, Cl and SO4 in river water of study area.
Sedimentology
Hadi Amin-Rasouli; Hossein Azizi; shahla mahmodyan
Abstract
The Upper Cretaceous succession (UCS) of the north Sanandaj-Sirjan zone consists of five units. The units are 2000 m thick, including shale, sandstone, limestone, intrafomational conglomerate with interbedded basaltic- andesitic lava. This succession is unconformably underlain by Lower Cretaceous and ...
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The Upper Cretaceous succession (UCS) of the north Sanandaj-Sirjan zone consists of five units. The units are 2000 m thick, including shale, sandstone, limestone, intrafomational conglomerate with interbedded basaltic- andesitic lava. This succession is unconformably underlain by Lower Cretaceous and overlain by Paleocene conglomerates. The geochemistry of the samples represents ratios of Al2O3/TiO2 (18-22), La/LuCN (5.43-24.4), La/Sc (0.51-2.53), Th/Sc (0.42-0.68), LREE/HREE (Nd/ErCN > 5), and negative anomalies of Eu/Eu* (0.26-0.89) and Nb/Nb* (0.14-0.82). These characteristics indicate that the samples are immature, first-order sediments, and were eroded from intermediate to acidic arcs in the subduction zone. The volcanic rocks were formed during the intracrustal melting of an altered oceanic slab at high pressures in the garnet-amphibolite facies. The geochemical compositions and vertical lithofacies stacking patterns of the UCS imply that the depositional environment has changed during sedimentation from a trench to trench slope and forearc basins arising from continent-ward migration of the magmatic arc. The activities of Late Cretaceous volcanism resulted in the upwelling of anoxic water, demise of planktonic, and formed pyrite in the deposits. Samples on the Th/Yb-Ta/Yb diagram fall in the ACM and WPVZ fields, indicating tectonic evolution from low-gradient subduction to extensional volcanic conditions.
S. H. Tabatabaei; A. Aghaei Araei
Abstract
This paper describes the result of a study on the determination of geotechnical properties of improved soil treated by quick lime and hydrated lime. Soil samples are mixed with quick lime and hydrated lime in various portions. The geotechnical properties investigated are ...
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This paper describes the result of a study on the determination of geotechnical properties of improved soil treated by quick lime and hydrated lime. Soil samples are mixed with quick lime and hydrated lime in various portions. The geotechnical properties investigated are compaction characteristics, Atterberg limits, compressive strength and CBR. It is observed that the dry density of soil treated with hydrated lime decreases and the optimum water content increases, while there is no noticeable change in dry density and optimum moisture content of soil treated with quick lime. The plasticity index of admixtures indicates a descending trend; however, it is more pronounced in samples treated by quick lime. Addition of small amount of lime causes significant increase in compressive strength of admixtures and increases with curing time. The effect of the quick lime is more significant than the hydrated lime. CBR tests show a trend similar to that observed for compressive strength tests. The optimum amount of hydrated and quick lime for improvement of the soil is presented.
