Stratigraphy and Palaeontology
Hossein Gholamalian; Roya Fanati Rashidi
Abstract
Kazhdumi Formation strata in Anguran section (NW Bandar Abbas) are investigated and eight echinoid species belonging to eight genera have been identified. These species are: Tetragramma malbosii, Orthopsis ruppelli, Phyllobrissus aff. angustatus, Epiaster dartoni, Hemiaster sp., Pliotoxaster comanchei, ...
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Kazhdumi Formation strata in Anguran section (NW Bandar Abbas) are investigated and eight echinoid species belonging to eight genera have been identified. These species are: Tetragramma malbosii, Orthopsis ruppelli, Phyllobrissus aff. angustatus, Epiaster dartoni, Hemiaster sp., Pliotoxaster comanchei, Iraniaster douvillei, Coenholectypus planatus. Iraniaster douvillei that has already been reported from the Coniacian – Santonian beds of Lorestan Zone (West of Iran); is present in the Albian – Cenomanian strata of Anguran section. So; we can propose the new range of Middle Albian – Santonian for this species. Kazdumi Formation in the studied area has the age of Middle Albian to Early Cenomenian on the basis of foraminifers those accompany with echinoids. This formation conformably overlies the Dariyan Formation and disconfomably underlies the Gurpi Formation.
Sedimentology
Javad Anjerdi; Mahdi Jafarzadeh; Adel Najafzadeh; Rahim Mahari
Abstract
In this research, a combination of petrography, geochemistry and heavy minerals analysis methods are implemented for investigating the provenance of quartzarenitic and subarkosic sandstones of Ilanqareh Formation with Late Devonian age in Azerbaijan, south of Jolfa. Investigation of the quartz types ...
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In this research, a combination of petrography, geochemistry and heavy minerals analysis methods are implemented for investigating the provenance of quartzarenitic and subarkosic sandstones of Ilanqareh Formation with Late Devonian age in Azerbaijan, south of Jolfa. Investigation of the quartz types in the studied sandstones, geochemical characteristics of sandstones and shales of Ilanqareh Formation including Al2O3/TiO2 ratio and La/Sc against Co/Th ratios, illustrates that the dominant parent rocks of most of these deposits are granitic igneous ones. The presence of granitic parent rock along with the presence of euhedral zircon and tourmaline among the well-rounded indicate the erosion of uplifted blocks of Iranian basement in the rifted basin of Paleotethys as effective factor in providing sediments. However, geochemistry and heavy mineral assemblages confirm the recycling of sediments from older formations as another source of sediment. The petrography, geochemistry and heavy minerals also indicate the craton provenance and passive margin tectonic setting at the deposition time of the Ilanqareh sediments. According to the present study, one can consider a combination of uplifted source rock (Cadomian basement) and sedimentary recycling of older formations as main sources and Arabian craton as a subsidiary source in the supply of detritus sanstones of Ilanqareh Formation.
Geological Environment and Engineering
Ahmad Abbasnejad
Abstract
The purpose of this study is: to determine the geomorphological setting; to assess earthquake, flood, and subsidence hazards, as well as to evaluate the landscape of Iranian urban areas, based on geomorphological criteria. To access the aim, 210 cities, each one having more than 50,000 population, were ...
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The purpose of this study is: to determine the geomorphological setting; to assess earthquake, flood, and subsidence hazards, as well as to evaluate the landscape of Iranian urban areas, based on geomorphological criteria. To access the aim, 210 cities, each one having more than 50,000 population, were investigated. In this study, Google Earth and satellite pictures, aerial photographs, and geological and geomorphological maps were used and, if needed, field investigations were undertaken. This study showed that the number of urban areas totally or partly lie on alluvial fans, flat surfaces, terraces, synclines, piedmonts, anticlines, and deltas are 103, 34, 26, 39, 27, 8, and 11 cases, respectively. The numbers on volcanic cones, cliffs, and wetlands are only 2, 1, and 1 cases, respectively. Also, 158 cases lie only on one landform and the remaining 52 cases predominately lie on two kinds of landforms. There are 82 and 90 cities at the high threat of earthquake and flood and the numbr of cities at the threat of surficial and qanat subsidence are 60 and 47 cases, respectively. The urban areas with uniform and good landscapes are 71 and 52 cases, respectively. The presented table demonstrates the geomorphological settings; the earthquake, flood and subsidence hazard levels and the landscape status of the 210 studied urban areas.
Stratigraphy and Palaeontology
Arash shabanpour Haghighie; Lida Bakhshandeh; Tayebeh Mohtat; Masood Zamanipedram; Seyed hamid Vaziri
Abstract
In this research the Gurpi Formation in the Zagros Basin outcropping in the Dasht-e Arjan section, Shiraz province ,for the purpose of biozonational and Paleobathymetric studies were investigated. The thickness of these sediments is about 130 m and consists of Limestones and Shales.To determine the palaeobathymetry ...
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In this research the Gurpi Formation in the Zagros Basin outcropping in the Dasht-e Arjan section, Shiraz province ,for the purpose of biozonational and Paleobathymetric studies were investigated. The thickness of these sediments is about 130 m and consists of Limestones and Shales.To determine the palaeobathymetry of the Gurpi Formation, Planktonic and benthic foraminifera were investigated . A depth of about 270m to 510m was determined for these sediments based on the ratio of planktonic foraminifera to the total assemblages of foraminifera after omitting infaunal benthic foraminifera (%P*) by using the equation D = e (3.58718+(0.03534 × %P* )).In this study sixty-two species of planktonic foraminifera belonging to eighteen genera were recognised .According to the studied planktonic foraminifera the Upper Cretaceous deposits in this area were divided into nine biozones as following :biozone1- Dicarinella concavata Interval Zone. Biozone2- Dicarinella asymetrica Total Range Zone. Biozone3- Globotruncanita elevata Partial range zone .Biozone4- Globotruncana ventricosa Interval Zone. Biozone5- Radotruncana calcarata Interval zone. Biozone 6- Globotruncanella havanensis Partial Range Zone. Biozone7- Globotruncana aegyptiaca Interval Zone. Biozone 8- Gansserina gansseri Interval Zone. Biozone 9- Contusotruncana contusa Interval ZoneBased on the studied planktonic foraminifera the Early Santonian to Maastrichtian ages were determined for the sediments .
Tectonics
Mehdi Tavakoli Yaraki; Seyyed Ahmad Alavi; Mohammad Reza Ghassemi; Iraj Abdollahie fard
Abstract
The significance of mechanical stratigraphy of rocks in kinematics of folds has long been of interest to structural geologists. Parameters such as sedimentary facies variations and thickness of incompetent layers play major role in activity of these layers as detachment horizons. The purpose of this ...
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The significance of mechanical stratigraphy of rocks in kinematics of folds has long been of interest to structural geologists. Parameters such as sedimentary facies variations and thickness of incompetent layers play major role in activity of these layers as detachment horizons. The purpose of this study is to investigate the role of mechanical stratigraphy on fold geometry in the Aghajari and Pazanan anticlines within the Dezful Embayment zone. For this purpose, we have used seismic profiles, stratigraphic data and petrophysical logs as well as the previous stratigraphic works in study area. Results show that the Garau Formation is the major intermediate detachment level in the Aghajari structure, and has a significant control on folding geometry of the competent sequences of the Fahliyan to Asmari Formations. The Dashtak Formation and other incompetent evaporatic Formations of Middle-Upper Jurassic also have been active in the Aghajari structure. In contrast, in most parts of the Pazanan structure, the Garau and the Jurassic Formations do not have appropriate mechanical properties to act as intermediate detachment levels due to their change into hemipelagic facies and limestone (Surmeh Formation) respectively. Based on the evidences, the facies change in the abovementioned Formations occurs between the Pazanan and Aghajari anticlines. It seems that activity of the Hendijan-Izeh paleo-high also has some control on facies of the Garau Formation. Based on geometric characteristics and a geometric conceptual model provided for development of these structures, the folding style of the anticlines is suggested as an asymmetric faulted detachment fold type.
Tectonics
Ali Bandegani; Ali Yassaghi; Mohsen Eliassi
Abstract
In this paper, the structural evolution of Bamu fault zone located in the Zagros folded belt zone is presented as an example of northeast-trending fault zone in the Zagros, using the kinematic and dynamic analysis of accompanied structures. Based on structural and paleostress analyzes two phases of shortening ...
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In this paper, the structural evolution of Bamu fault zone located in the Zagros folded belt zone is presented as an example of northeast-trending fault zone in the Zagros, using the kinematic and dynamic analysis of accompanied structures. Based on structural and paleostress analyzes two phases of shortening were determined as NE and NNE. In order to define the chronology of the deformation stages in the region, the relationship between fault structures and folds in the folded rock formations has been utilized. The result showed that the first compression stress trend in the area was NE that caused formation of the Bamu transverse Fault with left-lateral strike-slip mechanism and its accompanied structures. Since this stage of deformation has affected the Oligocene- early Miocene formations, more likely occurred at this time. During the next phase the shortening direction, due to change in the collision zone direction of the Arabian-central Iran in the Miocene-Pliocene, has changed to NNE which causes development of younger structures in the form of folding and reverse faulting in the fault zone. This shows that the NE-trending fault zones, like other major NW-faults, in Zagros affected by the change in the convergence of Zagros collision.
Economic Geology
Morteza Delavari; Amir Ali Tabakh Shabani; Samaneh Ghanbari
Abstract
The Oligocene dacitic volcanic rocks display widespread exposures in south of Julfa (eastern Azerbaijan). They generally show porphyritic to hyalo-porphyritic textures with major minerals of plagioclase, amphibole, quartz and biotite. Electron probe micro analyzer (EPMA) data indicates oscillatory zoning ...
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The Oligocene dacitic volcanic rocks display widespread exposures in south of Julfa (eastern Azerbaijan). They generally show porphyritic to hyalo-porphyritic textures with major minerals of plagioclase, amphibole, quartz and biotite. Electron probe micro analyzer (EPMA) data indicates oscillatory zoning and chemical variation of amphiboles (pargasite and edenite). The plagioclase crystals are, chemically, andesine (An= 29-51%) which mostly display oscillatory zoning. Based on geobarometric calculations, plagioclase displays pressures of 5 to 8 kb and amphiboles demonstrate different pressure ranges of 1.5 to 3 and 5 to 9 kb. Moreover, geothermometric calculations of plagioclase and amphibole provide temperatures of 1020-1050 and 850-900 °C, respectively. On the basis of geobarometric results, crystallization and growth of the minerals took place in magmatic chambers of different levels. Some of the amphiboles nucleated in lower continental crust and subsequently grown during magma ascent in middle crust whereas some others crystallized in the upper continental crust. Therefore, existence of minerals of different levels inside the studied rocks could be related to magma mixing in shallow magma chambers.
Economic Geology
Maryam Emami Jafari; Saeed Alirezaei; Iraj Rasa; Jochen Kolb
Abstract
The Hired gold deposit in the Lut block, East Iran, is closely associated with an intermediate-mafic intrusive complex consisting of granodiorite to diorite, hornblende quartz-monzonite, and gabbro-diorite intruded into Eocene volcanic rocks. The intrusions are distinguished by high contents of CaO, ...
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The Hired gold deposit in the Lut block, East Iran, is closely associated with an intermediate-mafic intrusive complex consisting of granodiorite to diorite, hornblende quartz-monzonite, and gabbro-diorite intruded into Eocene volcanic rocks. The intrusions are distinguished by high contents of CaO, FeOt, and MgO, and rather low K2O+Na2O implying they crystallized from weakly differentiated magmas. This subject, and the relatively high Mg# (36.36 to 52.32) imply the involvement of a mantle source in the production of the parent magma. The intrusions are metaluminous, calc-alkaline to high-K calc-alkaline, and distinguished by the occurrence of ilmenite as an accessory mineral. Mineralization occurs in veins and veinlets disseminations in the granodiorite intrusion and the volcanic rocks, closely associated with tourmaline, silicic, and carbonate alterations, and is distinguished by abundant pyrrhotite, arsenopyrite, pyrite, and minor chalcopyrite, galena and sphalerite. Gold occurs mostly as submicroscopic grains in the pyrite and arsenopyrite. The mineralogical and geochemical attributes of the intrusive complex, and the ore mineralogy, allow the Hired to be classified as a gold deposit related to reduced I-type granitoids. The reducing nature of the parent magma can be explained by introduction of reduced crustal materials into the source area, and/or assimilation of carbonaceous metasedimentary rocks.
Sedimentology
Mahmoud Sharafi; Mahdi Jafarzadeh; Aram Bayet-Goll; Razieh Lak
Abstract
The Urmia Lake, which is a tectonic depression in the northwest of Iran, has received a lot of eroded sediments of the geological records of the lake watershed. Because of the constant drought in the recent years, sediments have been subjected to the wind erosion and thus are an important source for ...
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The Urmia Lake, which is a tectonic depression in the northwest of Iran, has received a lot of eroded sediments of the geological records of the lake watershed. Because of the constant drought in the recent years, sediments have been subjected to the wind erosion and thus are an important source for local and regional emission during dust storms. In this research the south and west sediments of the Urmia playa lake have studied on the parent rock issue. Bivariate plots such as Th/Co versus La/Sc and TiO2 versus Al2O3 and comparison proportion of the trace elements such as La/Sc, Th/Sc, La/Co, Th/Co and Cr/Th display mainly the felsic and partly basic rocks source for the studied sediments. Major and trace spider plots of the studied sediments display their depletion with respect to Sc, V, Cr, Ni and enrichment with respect to Th and Sr, confirm mainly a felsic and partly mafic and ultramafic source rocks. Geochemistry of the major elements shows the dry climatic conditions during deposition of Urmia Lake sediments, suggested by bivariate plots of SiO2 against the sum of Al2O3, K2O and Na2O as well as the amount of chemical index of weathering.
Petrology
sara shakiba; ali asghar sepahi; Mohammad reza Ghasempour; kazu nakashima
Abstract
Alvand plutonic body is one of the largest intrusive plutons in northern part of Sanandaj-Sirjan zone which is located in south of Hamadan city. It is composed of porphyroid and leucocratic granitoids, basic intrusive rocks, and abundant enclaves in various sizes and in a variety of forms. Biotites of ...
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Alvand plutonic body is one of the largest intrusive plutons in northern part of Sanandaj-Sirjan zone which is located in south of Hamadan city. It is composed of porphyroid and leucocratic granitoids, basic intrusive rocks, and abundant enclaves in various sizes and in a variety of forms. Biotites of porphyroid monzogranite, diorite, felsic microgranular enclave, mafic microgranular enclave and surmicaceous enclaves are located in magnesian biotites and biotites of norites in phlogopite field. Orthopyroxenes of norite are clinoenstatite and orthopyroxenes of mafic microgranular enclaves are clinofrosilite. Based on the Ti-in-biotite thermometer, temperature of monzogranite porphyroid is 662 to 734 oC, norite is 688 to 776 oC, diorite is 598 to 724 oC, surmicaceous enclaves temperature is 662 to 687 oC, felsic microgranular enclaves is 694 to 712 oC and mafic microgranolar enclaves is 635 to 737 oC. the enclaves of the Alvand plutonic body and their host rocks are located in the field of calc-alkaline suite. Orthopyroxenes in the norite and mafic microgranular enclaves indicate that rocks of the Alvand intrusive complex are located in the field of high oxygen fugacity rocks. It is in accordance with calc-alkaline property of rocks and is consistent with the subduction-related tectono-magmatic environment.
Stratigraphy and Palaeontology
Mahnaz Parvaneh Nejad Shirazi; M. Seddighi; P. Balicheh khorram abadi
Abstract
This study deals with lithostratigraphy, biostratigraphy, microfacies analysis, and depositional setting of the Jahrum Formation in Chellehgah Sepidan section, NW Shiraz. Vertical changes in lithological characteristics led to recognition of 15 lithotypes. The Jahrum Formation, in this area, rests conformably ...
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This study deals with lithostratigraphy, biostratigraphy, microfacies analysis, and depositional setting of the Jahrum Formation in Chellehgah Sepidan section, NW Shiraz. Vertical changes in lithological characteristics led to recognition of 15 lithotypes. The Jahrum Formation, in this area, rests conformably (with a gradational boundary) on the Pabdeh Formation and is overlain unconformably by the Asmari Formation. Micropaleontological analyses based on benthic foraminifera (Nummulites striatus, N. cf. fabianii, N. gr. bullatus-garganicus, Spiroclypeus sp.) suggest a middle-upper Eocene age for the formation. Facies analyses allowed to recognize the 6 facies (including 12 microfacies) for the examined strata. The results also suggest that the Jahrum Formation deposited in a homoclinal ramp.
Exploration and Mining
Mojtaba mohammadi; Seyed Mahmoud Fatemi Aghda; Mehdi talkhablou; َAkbar Cheshomi
Abstract
Description and Understanding the sedimentary environment helps a lot in the initial estimation of the engineering properties of materials and planning of geotechnical studies. Most of the quaternary sediments (coarse and fine grained) of the Isfahan city were deposited by the Zayandehrood river. Understanding ...
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Description and Understanding the sedimentary environment helps a lot in the initial estimation of the engineering properties of materials and planning of geotechnical studies. Most of the quaternary sediments (coarse and fine grained) of the Isfahan city were deposited by the Zayandehrood river. Understanding the geotechnical characteristics and subsurface development of these sediments are essential in the old sedimentary environment for a couple of reasons. Firstly, it is difficult to determine the geotechnical characteristics of coarse-grained sediments and there is uncertainty in the subsurface development of these sediments at distant locations from the Zayandehrood river. Secondly, it is development of construction and the necessity of digging underground spaces Therefore, in this study, using the geotechnical data of 384 boreholes, maps of the approximate range of coarse-grained sediments of the Zayandehrood River were prepared at depths of 5, 10, 20 and 30 m and their geotechnical characteristics were statistical analyzed by the results of laboratory and in situ tests. The results show that the geotechnical characteristics of coarse-grained sediments do not change significantly with the change of depth and the approximate range of subsurface expansion of this river has been in the past in places other than the present river route.
Economic Geology
Maryam Honarmand; Ghasem Nabatian; Mahtab Aflaki; Mohammad Ebrahimi
Abstract
Geology, geochronology and tectonic setting of the Moghanlou mylonite gneiss and granite bodies, west of Zanjan Abstract The Moghanlou mylonite gneiss and granite assemblage is located in the west of Zanjan forming a part of the magmatic-metamorphic association in the Takab area. The Moghanlou assemblage ...
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Geology, geochronology and tectonic setting of the Moghanlou mylonite gneiss and granite bodies, west of Zanjan Abstract The Moghanlou mylonite gneiss and granite assemblage is located in the west of Zanjan forming a part of the magmatic-metamorphic association in the Takab area. The Moghanlou assemblage comprises of leucogranite and biotite granite intrusions which have surrounded the gneiss body. The zircon U-Pb dating shows the ages of 563±6.5 Ma for the mylonite gneiss, 576±13 Ma for the biotite granite and 559±6 Ma for the leucogranite intrusions. Moreover, the samples from the Moghanlou assemblage display high-K calc-alkaline and slightly peraluminous affinities, except those from the leucogranite which are low potassium samples due to the sodic alteration and albitization of the K-feldspars. The trace element patterns suggest LILE and LREE enrichment and HFSE and HREE depletion as well negative anomaly of Nb, Ta and Ti. In general, the geochemical features of the Moghanlou intrusions are comparable with the melts formed from crustal partial melting in magmatic arc environment. The Moghanlou assemblage is analogues to other Late Neoproterozoic-Early Cambrian igneous and metamorphic associations in Iran and Turkey which are related to the igneous activity along the Cadomian magmatic arc, in north of Gondwana supercontinent.
Stratigraphy and Palaeontology
Parisa Mohammadi; Abbas Ghaderi; Ali Reza Ashouri
Abstract
The Julfa region in East Azerbaijan Province exhibits one of the best continuous marine sedimentary successions across the Permian to Triassic boundary. The present study is focused on the brachiopod contents of the Julfa beds in Qareh-Goz section (41.5 m thickness) in the south of Julfa. This study ...
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The Julfa region in East Azerbaijan Province exhibits one of the best continuous marine sedimentary successions across the Permian to Triassic boundary. The present study is focused on the brachiopod contents of the Julfa beds in Qareh-Goz section (41.5 m thickness) in the south of Julfa. This study is led to the determination of 11 genera and 21 species of the orders Athyridida, Orthotetida, Orthida, Productida, Spiriferida, and Terebratulida, all representing the Cathaysian bioprovince for this area in the Western Paleotethys. Accordingly, four Wuchiapingian biozones, including Araxilevis intermedius Zone, Araxilevis intermedius-Permophricodothyris ovata Interval zone, Permophricodothyris ovata Zone, and Transcaucasathyris araxensis Zone, have been detected. These biozones correlate well through the other stratigraphic sections of the Julfa area in the Ali Bashi and Zal Mountains, Dorasham section in the Transcaucasia, Hembast Formation in the Abadeh area, and Nesen Formation in the central Alborz, approving the potential of these brachiopods in biocorrelation at a regional scale in the Late Permian.
Stratigraphy and Palaeontology
Behzad Saeedi Razavi; mozhgan rikhtehgarzadeh; saeedeh senemari
Abstract
In order to study the biostratigraphy of Sarvak and Ilam in wells A1 and A2 of Binak oilfield, B of Gachsaran oilfield, C of Aghajari oilfield and D of Rag-Sefid oilfield, numerous thin sections have been studied microscopically In the biostratigraphic study of 5 biozones in the Sarvak and Ilam formations, ...
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In order to study the biostratigraphy of Sarvak and Ilam in wells A1 and A2 of Binak oilfield, B of Gachsaran oilfield, C of Aghajari oilfield and D of Rag-Sefid oilfield, numerous thin sections have been studied microscopically In the biostratigraphic study of 5 biozones in the Sarvak and Ilam formations, the following fields were introduced: 1-Oligostegina flood zone, 2- Nezzazata – Alveolinids assemblage zone, 3- Rudist debris zone, 4 -Nezzazatinella – Dicyclina assemblage zone, 5- Rotalia skourensis – algae assemblage zone and Oligostegina food zone. Based on the study of age of Sarvak Formation from Late Albian to Turonian, and for Ilam Formation from Coniasian to Santonian. Based on the biostratigraphy correlation and thickness analysis of biozones introduced in the two studied formations, the depth of the Zagros basin from northwest to southeast decreases dramatically.
Tectonics
Mohammad Ali Ghanbarian; Ali Yassaghi
Abstract
This research has presented the results of the structural and microstructural analyses of the Faryadoun region which is located in the NE of the Fars province. In this research, a new NW-striking belt has been introduced in the central part of Zagros hinterland and NE of the Sanandaj-Sirjan metamorphic ...
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This research has presented the results of the structural and microstructural analyses of the Faryadoun region which is located in the NE of the Fars province. In this research, a new NW-striking belt has been introduced in the central part of Zagros hinterland and NE of the Sanandaj-Sirjan metamorphic belt. The mean attitudes of the foliation and lineation in this new belt are 315˚, 57˚ NE and 23˚, 116˚, respectively. The study of kinematic indicators revealed the occurrence of a sinistral top-to-the NW shear in this new belt which is different with the known dextral deformation in the central region of the Sanandaj-Sirjan metamorphic belt.
Economic Geology
Mahdi Ghorbani- Dehnavi; Azadeh Malekzadeh -Shafaroudi; Mohammad Hassan Karimpour
Abstract
Chah-Nar Pb-Zn deposit is located south of Rutchun plain, 110 km SW Baft, within Sanandaj- Sirjan Zone. Mineralization occurs at calitic-dolomitic marble of Rutchun complex as epigenetic with structural control. Paragenetic minerals are galena and minor sphalerite and pyrite associated with ...
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Chah-Nar Pb-Zn deposit is located south of Rutchun plain, 110 km SW Baft, within Sanandaj- Sirjan Zone. Mineralization occurs at calitic-dolomitic marble of Rutchun complex as epigenetic with structural control. Paragenetic minerals are galena and minor sphalerite and pyrite associated with quartz, and minor calcite and dolomite, as gangue minerals. These minerals show veinlets, open space filling, breccia, and disseminated textures. Galena can be seen in the form of coarse grain crystal and cuboctahedral texture and fine grain crystal. Silicification and carbonatization are the most important alteration zones. Galena chemistry indicates galena is Ag, As, Cd and Zn -rich and Sn, Bi-poor. Sb/Bi ratio in galena is close to 3, which is indicator of low temperature deposits. Host rock type, stratabound and epigenetic mineralization, postsedimentary fault controlling, texture, ore types and gangue minerals, and lack of significant correlation between mineralization and igneous activities, chemistry of galena, indicate that Chah-Nar deposit is similar to MVT deposits, although it has some differences with this deposits type.
Sedimentology
B. Mirzapour; R. Lak; M. Aleali; M. Djamali; R. Shahbazi
Abstract
Lake Urmia is one of the largest salt supersaturated lakes in the world that is located in northwestern Iran. Many wetlands are located around of Lake Urmia, especially in the southern part of the lake. Wetlands are important as a platform for recording environmental and climatic events. The ...
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Lake Urmia is one of the largest salt supersaturated lakes in the world that is located in northwestern Iran. Many wetlands are located around of Lake Urmia, especially in the southern part of the lake. Wetlands are important as a platform for recording environmental and climatic events. The subject of this research is studying sedimentology and statistical parameters of sedimentology in the analysis of different sedimentary environments in the sediments of southern wetlands around Lake Urmia, including Kani Barazan and Solduz wetlands. The purpose of this study is reconstructing the fluctuations of the water table of Lake Urmia and its effect on wetland areas in the Holocene period. For this purpose, sedimentary cores with maximum depth of 12 meters and total depth of about 200 meters using a handi auger and 8 hole cores by a vibra corer were collected and examined. Sedimentary facies were identified and separated based on texture and sediment structure, composition of destructive sediments and organic matter, color, presence of plant remnant and shell residues and other macroscopic components. Sampling was performed based on changes in the type of sediments and sedimentary facies. 150 sediment samples were separated for grain size analysis. The samples were analyzed using two methods, wet sieving and particles smaller than sand (silt and clay) by laser device (Laser particle Sizer Analysette). Statistical parameters of sedimentology were calculated using Sedilizer software and were analyzed by SPSS software. Two samples of plant remnant were dated by C14-AMS isotope method. The results indicate that there are 8 facies, belonging to 3 sedimentary environments of lake, wetland and alluvial. The dating results show the average sedimentation rate in the southern part of Lake Urmia is about 0.5 mm per year. However, sedimentation rates vary in different sediment depths. According to the analysis of different cores, the reconstruction of the paleogeography of the south of Lake Urmia and it`s extention had been done in the last 20,000 years. This study shows that in the late quaternary Lake Urmia has expanded to the beginning of the current Siminehrud. At the late Pleistocene and the early Holocene, the coastline regression in the southern part and the alluvial sediments of the Zarrinehrood and Siminehrood rivers occurred in the south of the region. The late Holocene was associated with decreasing water table, slightly dry conditions (around 4000 years ago) and the expansion of marginal playa. The situation in the region has been permanent for about 2000 years.
Sedimentology
Somayeh Parham; Alireza Piryaei; Mansur Ghorbani; Seyyed Reza Moosavi Harami
Abstract
Late Cretaceous in Zagros encompasses regional tectonics and caused foreland basin to form in northeast of the Arabian Plate. Salt tectonics is also locally affected this area. One of the time periods that can better picture this tectono-sedimentary evolution is Maastrichtian. In order to investigate ...
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Late Cretaceous in Zagros encompasses regional tectonics and caused foreland basin to form in northeast of the Arabian Plate. Salt tectonics is also locally affected this area. One of the time periods that can better picture this tectono-sedimentary evolution is Maastrichtian. In order to investigate this evolution in the Maastrichtian time, a regional cross-section was made inthe Fars outcrops and wells. A sedimentological study and sequence stratigraphy have been accomplished along this transect. Maastrichtian deposits consist of the upper part of the Gurpi and the Tarbur formations in the studied transect. Based onsedimentological investigation, 14microfacies have been identified. This microfacies were deposited in 4microfacies belt including tidal flat, restricted and open lagoon, reef and open marine in a shelf carbonate platform. Based on sequence stratigraphic studies, 3 sedimentary sequences were identified in the studied interval. Correlation along the transect revealed that the Maastrichtian deposits occurred on the forebulge of Zagros foreland basin. It is also concluded that the fore-buldge shows a nearly smooth topography and thus accommodation space is homogeneous. Hence the thickness of the Maastrichtian deposits does not vary so much along this transect. Thickness anomaly in Namak-dehkuyeh occurs as a result of salt structure which decreased accommodation space.
Tectonics
Firouzeh Shavvakhi; Saeed Madanipour; Ebrahim Rastad
Abstract
South Natanz Area is structurally located in the western part of the Central Iranian structural zone and central part of the Orumieh-Dokhtar magmatic belt at southwestern termination of the Qom-Zefreh Fault. Our structural data represents older generation of E-W to NW-SE thrust faults as Fasakhod Fault ...
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South Natanz Area is structurally located in the western part of the Central Iranian structural zone and central part of the Orumieh-Dokhtar magmatic belt at southwestern termination of the Qom-Zefreh Fault. Our structural data represents older generation of E-W to NW-SE thrust faults as Fasakhod Fault that juxtaposes Permian- Triassic (Jamal, Nayband and Shotori Formations) over younger rock units. Most of the thrust faults have been cross cut with younger generation of strike-slip fault system. These mainly post Eoene strike slip fault systems are structurally linke to Qom-Zefreh Fault zone. On the other hand, they developed as strike slip orders of the Qom-Zefreh Fault system in central part of the Orumieh-Dokhtar magmatic belt. Integration of the structural data set with stratigraphic unconformities observed in the south Natanz represet regional folding of the area during pre Early Cretaceous time. Subsequently, it has experienced regional extension as observed in the other parts of the central Iran during Early Cretaceous time. Major thrust faulting of the area has been occuered during post Late Createcous time. The final post Oligocene strike slip faulting related to the activation of the Qom- Zefreh fault has overprinted and cross cut older structural features.
Stratigraphy and Palaeontology
Fereshteh Sajjadi; Firoozeh Hashemi Yazdi; Hossein Hashemi
Abstract
Reasonably diverse and very well-preserved palynomorphs including miospores, dinoflagellate cysts, foraminiferal test linings, acritarchs (sensu lato) and fungal spores occur in the Dalichai Formation, Yonjehzar, northeastern Tehran, central Alborz. The assemblages embrace 40 species of spores (assigned ...
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Reasonably diverse and very well-preserved palynomorphs including miospores, dinoflagellate cysts, foraminiferal test linings, acritarchs (sensu lato) and fungal spores occur in the Dalichai Formation, Yonjehzar, northeastern Tehran, central Alborz. The assemblages embrace 40 species of spores (assigned to 29 genera), 18 species of pollen (distributed among 10 genera) and 54 species of dinoflagellates (assigned to 28 genera). According to the presence of such miospores species with known worldwide stratigraphic distribution as Klukisporites variegatus, K. scaberis, Concavissimisporites verrucosus, C. pricei, Osmundacidites senectus and Striatella spp. the host strata are conceivably dated as Middle Jurassic. Based on the stratigraphic distribution of miospores, Klukisporites variegatus-Araucariacites australis-Cerebropollenites macroverrucosus Assemblage Zone is recognized. Presence of some index dinoflagellate species led to identification of four biozones in the Dalichai Formation. These include in ascending order, Cribroperidinium crispum Total Range Biozone (late Bajocian), Dichadogonyaulax sellwoodii Interval Biozone (Bathonian - early Callovian), Ctenididinium continuum Interval Biozone (early - middle Callovian) and Subzone a (early - middle Bathonian). Co-ccurrence of dinoflagellate cysts with known vertical ranges, viz., Cribroperidinium crispum, Meiourogonyaulax valensii, Carpatodinium predae, Ctenidodinium combazii and Compositosphaeridium polonicum suggests a Middle Jurassic age (late Bajocian to middle Callovian) for the host strata corroborates the available miospores-based biostratigraphy. The miospores are attributed to the Pterophyta (69%), Coniferophyta (15%), Pteridospermophyta (7%), Cycadophyta (5%), Lycophyta (2%), Ginkgophyta and Bryophytes (1%). Considering the relative abundance of fern spores (69%) and their morphological diversity (19 genera), it can be concluded that fern and fern-allies dominated the coastal vegetation around the sedimentary environments of the studied strata and that they flourished under a warm climate with notable humidity. The study of paleoclimate using the Sporomorph EcoGroups model shows a high ratio of warmer/cooler sporomorphs and a low ratio of drier/wetter sporomorphs, which is another confirmation of this type of climate. Presece of such warm water dinoflagellate cysts as Gonyaulacysta centriconnata, G. jurassica, Nannoceratopsis pellucida, Tubotuberella apatela, Ctenidodinium continuum, Pareodinia halosa, P. ceratophora, paleogeographic reconstruction and geographical location of Iran in the Middle Jurassic supports the generalization proposed.
Economic Geology
Maryam Javidi Moghaddam; M.H Karimpour; Azadeh Malekzadeh Shafaroudi
Abstract
The Rashidi area, which comprises a part of the north Khur in eastern Iran is located at 120 km northwest of Birjand city. Preliminary prospecting in the area using the image processing of ASTER data by Spectral Angle Mapper (SAM) algorithm resulted in the identification of propylitic and argillic alteration ...
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The Rashidi area, which comprises a part of the north Khur in eastern Iran is located at 120 km northwest of Birjand city. Preliminary prospecting in the area using the image processing of ASTER data by Spectral Angle Mapper (SAM) algorithm resulted in the identification of propylitic and argillic alteration zones together with iron oxy-hydroxide minerals. The area consist of outcrops of Eocene pyroclastic rocks ranging from andesitic to rhyolitic in composition, intruded by diorite porphyry dikes. Vein mineralization in the area was mainly occurred along a fracture system hosted by andesitic tuff breccia unit. Vein copper mineralization was formed during two stages including the: (1) quartz-pyrite-chalcocite-tennantite assemblage, and (2) quartz-chalcocite-pyrite-sphalerite assemblage. The values of δ18O for quartz in the first and second stages of vein mineralization was 19.26 and 14.94 and the amount of δ18O water in equilibrium with quartz was 10.96 and 4.94 respectively that shows a magmatic origin and mixing with meteoric water in the second stage. Based on geology, vein geometry, fluid inclusion, and stable isotope geochemistry, the Rashidi Cu deposit can be classified as vein-type copper deposits, which has been formed along fault zones.
Economic Geology
nasrin khajehmohammadlou; Ali Asghar Calagari; Kamal Siahcheshm; Ali Abedini
Abstract
The Aghbolagh iron-copper skarn is located in ~21 km north of Oshnavieh, southwest of West-Azarbaidjan province. The intrusion of Cretaceous granitic body into the Cambrian Barut, Zagun, and Lalun Formations (carbonate, shale, and sandstone) was accompanied by development of calcic-type skarn, hornfels, ...
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The Aghbolagh iron-copper skarn is located in ~21 km north of Oshnavieh, southwest of West-Azarbaidjan province. The intrusion of Cretaceous granitic body into the Cambrian Barut, Zagun, and Lalun Formations (carbonate, shale, and sandstone) was accompanied by development of calcic-type skarn, hornfels, and marble in the study area. The garnets of the Aghbolagh skarn belong to solid solution series of grossularite-andradite in which andradite is the dominant phase (>80%). These garnets are isotropic and lack zonation. The pattern of REE distribution in these garnets shows the enrichment of LREE relative to HREE and also the occurrence of negative anomalies of Eu/Eu* and Ce/Ce*. The comparison of the distribution pattern of REE in garnets with those in igneous (granite and monzonite) and sedimentary (carbonates and sandstones) rocks demonstrates that the REE in garnets were derived mainly from the igneous rocks rather than the sedimentary units. The increase in Pr/Yb ratios in parallel with increase in the ƩREE is indicative of the magmatic origin of the ore-forming fluids in the Aghbolagh skarn. However, the lack of sensible variations between Ce/CE* and ƩREE values indicate that the meteoric waters might have also played a part in skarn-forming fluids at Aghbolagh.
Economic Geology
Mohammad Jafar Kupayi; Ebrahim Rastad; Saeed Madanipour; Sajjad Maghfouri
Abstract
Cretaceous sedimentary sequence in the Yazdan area is consisting of four rock units as, from the old to the new, clastic-carbonate (Kc), carbonate (Kl), Shale and marl (Km) sequences, and Sandy limestone and sandstone (Kls). The Kls unit is host of ore mineralization in the study area and formed from ...
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Cretaceous sedimentary sequence in the Yazdan area is consisting of four rock units as, from the old to the new, clastic-carbonate (Kc), carbonate (Kl), Shale and marl (Km) sequences, and Sandy limestone and sandstone (Kls). The Kls unit is host of ore mineralization in the study area and formed from four members. Ore mineralization in the Yazdan Deposit has occurred as a stratiform horizon in the sandstone units of the third member. Texture and structures studies, shown three ore facies with elemental zonation in the Yazdan Deposit. These ore facies includes, stringer zone, massive ore facies and the bedded ore facies. This ore facies formed from laminated and layered sulfide and sulfate minerals. Fluid inclusions studies represents 255-136 ° C of homogeneity temperature with an average temperature of 189 ° C. Also, the salinity of fluid inclusions was calculated to be between 14.6-6% NaCl (on average, 9.5% NaCl). Geological evidence, host rocks type, texture and structures, existence of ore facies with elemental zoning as well as fluid inclusion investigations indicate the Yazdan Deposit has most similarity with Sedex-type deposit.
Economic Geology
mahboobeh yaghobi; sasan bagheri
Abstract
In Eastern Iran, the Eocene platform deposits of northwest of Birjand, are a suitable case; because a thin thrust sheet of Eocene carbonate have had the possibility to slide and fold upon an upper cretaceous plastic footwall. Moreover, this carbonate sheet entirely covered the structural arc, conduct ...
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In Eastern Iran, the Eocene platform deposits of northwest of Birjand, are a suitable case; because a thin thrust sheet of Eocene carbonate have had the possibility to slide and fold upon an upper cretaceous plastic footwall. Moreover, this carbonate sheet entirely covered the structural arc, conduct us to recognize the origin of the bending. Achieving to this goal, we passed the structural arc along the six cross sections; four sections along radial trends and two transversal sections parallel to the inflection line. In these measurements, folds and thrust faults were defined as far as possible. The cross sections have been restored by the "Move Softwear". The amount of shortening along the radial sections were measured respectively from the east to the west are the 30-40% along A, 25-35% along B, 35-45% along C, and 15-25% along D; and along the transversal section are respectively from the south to the north about the 35-55% along E and 25-35% along F. The shortening amount in the platform carbonate at two-facing ends of the structural arc as well as the one along the inflection line are the greatest. The pattern of shortening in the arc seems to follow a buckle folding mechanism.
