Original Research Paper
Petrology
Mahsa Jamshidnia; manijeh Asadpour; Masoumeh Ahangari
Abstract
Qushchi gneisses in the north of Urmia city are a part of magmatic-metamorphic complex in NW of Sanandaj-Sirjan zone. Gneiss, with eldsparses and schist, form Precambrian basement of the area. These rocks contain lipidogranoblastic, augen, porphyroblastic and myrmekite textures, and composed of quartz+ ...
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Qushchi gneisses in the north of Urmia city are a part of magmatic-metamorphic complex in NW of Sanandaj-Sirjan zone. Gneiss, with eldsparses and schist, form Precambrian basement of the area. These rocks contain lipidogranoblastic, augen, porphyroblastic and myrmekite textures, and composed of quartz+ alkaline eldspars (orthoclase and microcline perthites) + plagioclase+ biotite± pyroxene, muscovite± amphibole± epidote +zircon+ opaque. Field, petrography and geochemical evidences were used to know the genesis of igneous (ortho) or sedimentary (para) of these gneisses. All the evidences imply an igneous origin (ortho) for the studied gneisses. In fact, the protolith of these gneisses are porphyritic granite to monzonite rocks and has calcareous-alkaline and peraluminous nature. It can be inferred that the protolith of these rocks which formed in the late Neoproterozoic, belong to the calc-alkaline magmas in active continental margins or volcanic arcs (VAG). Further tectonic events have transformed them into gneisses.
Original Research Paper
Sedimentology
Elmira Shahkaram; Mohammad Hosein Adabi; Davood Jahani; Seyed Hamid Vaziri
Abstract
The Dalichai Formation is the first rock unit of the Middle Jurassic in the Alborz sedimentary basin that has occurred in a marine environment. The boundary of the Dalichai formation with Shemshak Formation is erosional unconformable while it is concordant with Lar formation. Due to lithological similarity, ...
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The Dalichai Formation is the first rock unit of the Middle Jurassic in the Alborz sedimentary basin that has occurred in a marine environment. The boundary of the Dalichai formation with Shemshak Formation is erosional unconformable while it is concordant with Lar formation. Due to lithological similarity, the boundary of the Dalichai formation with the Lar formation is unclear. It is also very difficult to identify the primary carbonates mineralogy, due to the effects of diagenetic processes solely on the basis of petrographic studies. We studied a section of Sharaf mountain with a thickness of 1420m and 149 samples was studied. The study of the major and minor elements, the Oxygen and Carbon isotopes, and plotting of these values against each other represents that the Dalichai formation have had original aragonite mineralogy, and the nonmarine diagenesis have had the highest impact on them. Plotting the Sr/Ca ratio versus Mn value, shows that these carbonates are affected in a semi-closed to open diagenetic system. Using Sr, Sr/Na, Sr/Ca, Oxygen and Carbon isotopes, the boundary of this formation with the Lar Formation is recognized in thickness of 1200m. The diagenetic environment temperature for this section limestones is 32.9ºC.
Original Research Paper
Petrology
Maryam Daieparizi; Hamid Ahmadipour; Abbas Moradian
Abstract
In the Pariz area, (Kerman province), there are special deposits and in the geological maps, they have introduced as detrital unconsolidated Neogene Conglomerates (Ng). Detailed field observations of these deposits in this study showed that they are pyroclastic deposits from the post Eocene unknown explosive ...
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In the Pariz area, (Kerman province), there are special deposits and in the geological maps, they have introduced as detrital unconsolidated Neogene Conglomerates (Ng). Detailed field observations of these deposits in this study showed that they are pyroclastic deposits from the post Eocene unknown explosive eruptions. Stratigraphically, these units overlie the Eocene basaltic rocks, and their clasts are dacitic and rhyolitic in compositions, which means that they are completely different from the Eocene rocks. Genetically, these deposits are pyroclastic surges and flow deposits in association with the laharic units. Lithological features of these pyroclastics along with the absence of ducite or rhyolite lava flows and the relatively large dispersion of these deposits indicate that they have been formed by water bearing explosive eruptions. The clasts of these pyroclastic deposits contain plagioclase, amphibole, biotite and quartz and they are geochemically belong to the calcalkaline magmatic series. The geochemical characteristics of these rocks show that they formed in a post-collision environment and their geochemical nature are similar to the continental magmatic arc associations. These results are consistent with other studies on the post Eocene magmatic rocks of the Dehaj-Sardouieh belt.
Original Research Paper
Stratigraphy and Palaeontology
shahram navavajary; Iraj Maghfouri Moghaddam; Ali Reza Shahidi; Hamid Nazari
Abstract
Oligo-Miocene rocks are deposited between Pyrenean and Pasadenian orogenic phases. This rocks in central Iran back arc deposits are named Qom formation. There are well developed outcrops of Qom formation at the North of Central Iran zone. In order to study microbiostratigraphy of the formation, Three ...
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Oligo-Miocene rocks are deposited between Pyrenean and Pasadenian orogenic phases. This rocks in central Iran back arc deposits are named Qom formation. There are well developed outcrops of Qom formation at the North of Central Iran zone. In order to study microbiostratigraphy of the formation, Three sections, north west of Darjazin town , Bonak mount and Arvaneh were selected. In these sections Qom formation with discontinuity overlays the Lower Red formation and with the same quality under the Late Miocene Conglomerate with intercalations of Sandstone, which is equivalent to the Upper Red Formation is placed. The main lithological composition of the Qom Formation in the study area alternates between layers of limestone and Marl with intercalations of siliciclastic rocks. Members and submembers of the Qom formation type area are not visible in this area and can only based on the lithological characteristics divide to local units. Based on bentic foraminifera and other microbiostratigraphical data, Qom Formation age in north west-west of Semnan (Darjazin-After zone), which is located in the Central Alborz structural- sedimentary zone, is early Miocene epoch and Burdigalian stage, which is the equivalent of Borelis melo curdica-Borelis melo biozone.
Original Research Paper
Economic Geology
Hossein Bagherpour; Mir Ali Asghar Mokhtari; Hossein Kouhestani; Ghasem Nabatian
Abstract
Qoyjeh Yeylaq volcanic rocks is located approximately in the 120 km southwest of Zanjan, within the Central Iranian zone. The rock units in this area belong to the Cenozoic which consist of mainly Oligo-Miocene volcanic (Basaltic- andesitic lavas) and sedimentary rocks. Based on geochemical classification, ...
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Qoyjeh Yeylaq volcanic rocks is located approximately in the 120 km southwest of Zanjan, within the Central Iranian zone. The rock units in this area belong to the Cenozoic which consist of mainly Oligo-Miocene volcanic (Basaltic- andesitic lavas) and sedimentary rocks. Based on geochemical classification, the mentioned volcanic rocks are basalt, basaltic andesite and andesite in composition, and have calc- alkaline to high-K calc-alkaline affinity. In the primitive mantle normalized spider diagrams, all of the volcanic rocks show similar patterns with enrichment in LILE (Ba, Th, K, Pb) and negative anomalies of HFSE (Nb, Ti). These rocks show LREE enrichment relative to HREE and high ratio of LREE/HREE. Based on tectonomagmatic discrimination diagrams these volcanic rocks were formed in a continental arc setting. Based on geochemical data, it seems that volcanic rocks of the Qoyjeh Yeylaq area were formed from 5-20 % partial melting of a garnet- spinel lherzolite enriched mantle by subduction of Neo-Tethys under the central Iran, within the Orumieh- Dokhtar magmatic arc.
Original Research Paper
Geophysics
safieh farrokhi mogaddam; Abbas Alli Alli akbari bidokhti; Farhang Ahmadi givi; Mojtaba Ezam
Abstract
Salinity and water temperature are considered as important characteristics of water of different seas. The absolute values and variability of them in time and space determine life sustainability conditions, development of plants and animals and also types of human activity in seas. Water temperature ...
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Salinity and water temperature are considered as important characteristics of water of different seas. The absolute values and variability of them in time and space determine life sustainability conditions, development of plants and animals and also types of human activity in seas. Water temperature and salinity are important because of their effects on chemical and biochemical reactions of hydro-organisms. In this research the effects of climate change on physical characteristics of Persian Gulf including water temperature and salinity has been studied using numerical simulations and some observations. To carry out numerical simulation, the 1-dimension oceanic numerical model PROBE was used. The input data of the model includes meteorological information obtained from ECMWF and also initial values of the station. To simulate the vertical turbulence, the relations of Axcell-Liungman, Omstedt, Rodi, Pacanovski and Marchuk have been used for a station in the Persian Gulf and the results have been compared with some measurements and similar studies. The results of investigations show that limits of seawater and salinity variability model outputs are similar but the Omstedt relation shows more detailed changes in comparison to the others. The numerical results indicate that the temperature increase of the Persian Gulf over a decade can be as large as one to two degree Celsius, with some salinity increase as well.
Original Research Paper
Petrology
Mohammad Saadat; Robab Hajialioghli; Mohssen Moazzen
Abstract
The Qotur metamorphic complex in west of Khoy is consist of various metamorphic rocks including of metabasites, metapelitic and meta-calcareous rocks and serpentinites. The metagabbros form main outcropping rocks in the area. Plagioclase and pyroxene are the main porphyroclasts of metagabbros. Epidote, ...
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The Qotur metamorphic complex in west of Khoy is consist of various metamorphic rocks including of metabasites, metapelitic and meta-calcareous rocks and serpentinites. The metagabbros form main outcropping rocks in the area. Plagioclase and pyroxene are the main porphyroclasts of metagabbros. Epidote, tremolite/actinolite, calcite and chlorite are formed during low grade metamorphism of these rocks. Based on geochemistry results, protolite compositions of the investigated rocks are plotted on the gabbroic field of the classification diagram. They have calc-alkaline magmatic series. Considering the discrimination tectonic diagrams the Qotur metagabbroic rocks have been formed at the island arc tectonic setting. On the basis of U-Pb zircon geochronological data, the rocks are formed at 162.6±7.6 Ma corresponds to the late Jurassic (Oxfordian). On the basis of results obtained from isotopic dating and geochemical data of the Qotur metagabbros, we suppose that they formed related to the sialic back arc basin of Neotethys, Jurrasic Island arc rocks of Sevan-Akera zone corresponds to the North branch of Neotethys oceanic suture and/or in continuation of the Piranshahr and Serow ophiolites as a Zagros-Bitlis Zone. However perecise results will be need to tectonic works and more geochemical and isotopic data from variety of metamorphic and igneous rocks.
Original Research Paper
Hydrology
Mohamad Hosein Mahmudy Gharaie; Najmeh Rokhashmah; Asadollah Mahboubi; Seyed Reza Moussavi Harami
Abstract
The aims of this study are water quality assessment for drinking and industrial usages with refer to affective factors on water chemistry in North of Quchan plain, Razavi Khorasan province. 17 groundwater samples were collected for major cations (Ca2+, Na+, Mg2+, K+) and anions (HCO3-, SO42-, Cl-) analysis. ...
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The aims of this study are water quality assessment for drinking and industrial usages with refer to affective factors on water chemistry in North of Quchan plain, Razavi Khorasan province. 17 groundwater samples were collected for major cations (Ca2+, Na+, Mg2+, K+) and anions (HCO3-, SO42-, Cl-) analysis. According to Piper diagram, chemical composition of water samples is 29.4% Ca-SO4, 23.5% Na-SO4, 23.5% Mg-SO4, 11.8% Na-HCO3 and 5.8% Mg-HCO3. Based on Gibbs diagram, the main controlling process of the water composition is mainly water-rock interactions (weathering), rather than evaporation and precipitation. Schoeller diagram shows that most of water samples are categorized in moderate and acceptable classes. Also, based on water quality index (WQI), 70.59 % water samples are suitable for drinking usage. Increasing in SO42- concentration reduced the water quality for drinking purposes. Langelier index (LSI) shows 82.35 % water samples are scale forming and 17.65 % are corrosive. Scale forming of the water are due to high TH induced by carbonate dissolution (of Mozdouran and Tirgan Formations). In addition, corrosive property of some water samples is due to gypsum dissolution (from Shoorigeh Formation) and increasing of sulfate concentration in the groundwater.
Original Research Paper
Petrology
Sakine Moradi; Muhammad Reza Ghorbani; Shao- Yang Jing
Abstract
The Kahak mafic volcanic rocks in the central part of the Urumieh-Dokhtar Magmatic Arc are composed of basalts and basaltic andesite and show sub alkaline to transitional affinity. They are calc-alkaline based on the tholeiitic index (THL). U-Pb zircon dating yields ...
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The Kahak mafic volcanic rocks in the central part of the Urumieh-Dokhtar Magmatic Arc are composed of basalts and basaltic andesite and show sub alkaline to transitional affinity. They are calc-alkaline based on the tholeiitic index (THL). U-Pb zircon dating yields almost 60 (Middle Paleocene) and 24 to 19 Ma (Late Oligocene–Early Miocene) for andesitic basalt and basaltic rocks respectively. These rocks are identified by LREE and LILE enrichment and HFSE depletion with relatively negative or without Eu anomalies and E-MORB like pattern in multiple spider diagrams that.attributed to the subduction of the Neotethyan oceanic slab beneath the central Iranian microcontinent. Based on petrography, trace and rare earth elements, and isotopic features, fractional crystallization played a significant role during magma evolution in these rocks. Trace element modeling suggests that the studied mafic rocks were derived by partial melting within the spinel lherzolite mantle. Isotopic ratios also show that they resulted from lithospheric mantle metasomatized by released fluids from subducted slab sediments. The studied samples might have formed in the extensional regime followed by slab rollback and undergone a continental arc to back-arc basin transition during the Paleocene to Miocene. This basin might have been closed in the middle Miocene.
Original Research Paper
Tectonics
shima afkhami; Ahmad Alavi; Mohammad Reza Yamini; Mohamad Reza Ghasemi
Abstract
The main purpose of this study is to investigate and structureral analyzes of Sirri oil field by subsurface geophysical data. In order to Seismic interpretation from 3 seismic lines (LL3, LL4 and LL5) picked up by Iranian Offshore Oil Company and SIC-1 well Data was used. In addition to interpreting ...
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The main purpose of this study is to investigate and structureral analyzes of Sirri oil field by subsurface geophysical data. In order to Seismic interpretation from 3 seismic lines (LL3, LL4 and LL5) picked up by Iranian Offshore Oil Company and SIC-1 well Data was used. In addition to interpreting the geological horizons and understanding the stratigraphic-structural evolution of the region they have also been used. The study area is located in the south of Iran and in the Persian Gulf. In this study, the geological analysis of the area has been studied by two-dimensional seismic surveying method and petrophysical images (up to Darian Formation) and Petrel software. The results show that the rising of the salt dome related to the Hormuz series has affected the overlying Formations in these field, and has created a dome shaped state for most of the Formations. Rising of the salt and folding of the sediments eventually resulted in faulting of the sediments. During the study and measurement of the angle between the edges, it was found that 15.2% of the folds are open and 84.8% are of the soft folds.
Original Research Paper
Economic Geology
Kolsoum Fani Chenar; Mansour Ghorbani; Reza Kohansal; Jamshid Lotfian
Abstract
Ali abad chromites mines (north east of Forumad) are as a part of chromites assemblage dependent on ophiolite Sabzevar that are located in NW Sabzevar city. Chromitites deposits in these mines have been located as irregular lenses and layered or banded along with pods of dunite in depleted harzburgite. ...
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Ali abad chromites mines (north east of Forumad) are as a part of chromites assemblage dependent on ophiolite Sabzevar that are located in NW Sabzevar city. Chromitites deposits in these mines have been located as irregular lenses and layered or banded along with pods of dunite in depleted harzburgite. In attention to mineralogy observation, incongruent melting of orthopyroxenes and exsolution lamellae of clinopyroene in the orthopyroxenes, indicate that these rocks were originally formed at mantle pressures and temperatures conditions. Mineralography study on the textures and structures of Ali abad chromites indicate two types main textures that are primary and secondary. The primary textures and structures include massive and disseminated or separated grain. The milonitic, brecciated and tensional textures are from secondary types in chromites. On the basis of geochemical results the structural formula are calculated as the chromite minerals [(Mg,Fe2+)O (Cr,Al,Fe3+)2O3].These studies represent height percent Cr2O3 chromite mineral in disseminated texture than massive textures. Geochemical study on the chromitite area, site them in height Cr types and associated to podiform type that are originated from a parent melt with boninitic character resulting from high degree of partial melting of mantle peridotite in Supra Subduction Zone (SSZ).
Original Research Paper
Petrology
Ayoub Veisinia; Mohammad Ebrahimi; Bahman Rahibzadeh; rasoul Esmaeili
Abstract
Kamyaran ophiolitic complex located in the northeast Zagros orogeny along the crush zone between Arabian-Iranian plates. This complex outcropped between the Harsin ophiolites in southeast and Sarwabad ophiolite in northwest. Field observation reveal the fact that the Garmab Ophiolite in the northeast ...
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Kamyaran ophiolitic complex located in the northeast Zagros orogeny along the crush zone between Arabian-Iranian plates. This complex outcropped between the Harsin ophiolites in southeast and Sarwabad ophiolite in northwest. Field observation reveal the fact that the Garmab Ophiolite in the northeast of Kamyaran is a tectonic mélange including peridotites and gabbros cut by microgabbroic dikes. Olivine, clinopyroxene and orthopyroxene with chromian spinel made the peridotites minerals with mesh and porphyroclastic fabrics and Gabbros include plagioclase, clinopyroxene and minor amphibole with intergranular, pegmatoidic and interstitial texture. According to the geochemical results, gabbros have tholeiitic to calk-alkaline nature and show the MORB to island arc characteristics. According to the geochemical and geotectonic results, Garmab peridotites plotted to the abyssal peridotites area that represent from the residual mantle spinel lherzolite after extraction of 15–20% partial melting. The break-off of Neo-Tethyan slab and subduction of this slab branch beneath the oceanic lithosphere during cretaceous led to cessation of the Neo-Tethyan subduction beneath the Sanandaj-Sirjan block, and forming arc-back arc basin (second step of subduction) and related rocks in the Kamyaran ophiolite. Presence of tholeiitic to calc-alkaline magmatism is in response to the slab retreat in the Eurasian continental margin.
Original Research Paper
Economic Geology
Seyevahid Shahrokhi
Abstract
The chemical composition of chlorite group minerals show that physicochemical condition of crystallization and their formation. The chemical analysis of chlorite from biotite alteration has done based on 30 points of 8 rock samples by electron microprobe. The composition of chlorite samples is located ...
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The chemical composition of chlorite group minerals show that physicochemical condition of crystallization and their formation. The chemical analysis of chlorite from biotite alteration has done based on 30 points of 8 rock samples by electron microprobe. The composition of chlorite samples is located in repidolite- pychnochlorite domain. The mole fraction in the interlayer phase, range from 0.97 to 0.99, indicating a complete lack of smectite layers and purity of chlorite. Calculation of the structural formula of chlorites in Malvak area show that the number of silicon atoms are in the range of 2.64 to 2.91 (apfu) and the sum of the octahedral cations are 6 (apfu). Chlorites of the Malvak area are trioctahedral type. The low titanium content of chlorites, the presence of titanium minerals coexite with chlorite cleavage, and the presence of early biotite crystals are evidence of biotite to chlorite alteration. The mean temperature of chlorites in the Malvak area is 340 ºC, which corresponds to the temperature obtained with the geothermometry of biotite-altered to chlorites. Mesothermal type fluids from the granitoid mass in the study area have been effective in chlorite occurrence. Also, regional metamorphism has played an important role in the chlorite formation.
Original Research Paper
Hydrology
Ghazaleh Mohebbi Tafreshi; Mohammad Nakhaei; razieh Lak
Abstract
Land subsidence is a nonlinear and complex process that data-driven computational intelligence models can model it. In this study, the accuracy and efficiency of hybrid fuzzy logic gene expression planning hybrid model in estimating land subsidence risk and its factors in Varamin aquifer standardized. ...
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Land subsidence is a nonlinear and complex process that data-driven computational intelligence models can model it. In this study, the accuracy and efficiency of hybrid fuzzy logic gene expression planning hybrid model in estimating land subsidence risk and its factors in Varamin aquifer standardized. For this purpose, after selecting and gathering information from 15 factors affecting the subsidence event based on research records in the GIS environment, they were first standardized by fuzzy membership functions and then gene expression programming method was used to integrate the layers. Finally, using seven important statistical benchmarks based on radar image data, the model was validated in 4 different scenarios in input data and operators. The results showed scenario 1 with input parameters of bedrock level, Debi of pumping wells, groundwater drawdown, geology and operators, +, - ×, ÷, sqr, exp, Ln, ^ 2, ^ 3,3Rt, sin, cos, Atan, is the best model in training and testing. Accordingly, the groundwater drawdown parameter had the highest effect on land subsidence in the study area.
Original Research Paper
Economic Geology
Fatemeh Sabahi; Mohammad Lotfi; Peyman Afzal; nima nezafati
Abstract
Gardaneshir carbonate-hosted Pb-Zn deposit on the ground of study area located southwest of Ardestan in Isfahan province. Base on lithostratigraphy,the main structure, besides the small outcrops of Jurassic shales, has been made up of carbonate and detrital rock materials depending on Paleozoic,Triassic ...
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Gardaneshir carbonate-hosted Pb-Zn deposit on the ground of study area located southwest of Ardestan in Isfahan province. Base on lithostratigraphy,the main structure, besides the small outcrops of Jurassic shales, has been made up of carbonate and detrital rock materials depending on Paleozoic,Triassic and Cretaceous time stages. Dolomitic carbonate which is attributed to Shotori Formation , played the major role of host rock in ore-mineralization. Ore-mineral description obtained from the mineralized zone and caused the following ore-paragenesis in ascending order.of:pyrite,chalcopyrite,galena,sphalerite,malachite,cerussite,smithsonite,iron oxides and gangues of barite, quartz and calcite. Physico-chemical information of ore-solutions performed by entrapped fluid inclusion studies in gangue minerals. Liquid-rich two phase(L+V) inclusions as predominant types were recognized. These type of inclusions are homogenized into liquid state with a range of TH and related salinities between; TH :78 to 183 and 216 to 283°C, Salinity:3.5 to 9.7 and 10.2 to 25 wt% NaCl eq. The microthermometric data reflect the nature of two population of fluid inclusions originating from different sources. The source materials could have been provided by basinal brines, derived during compaction of sediments in a shallow sea environment and by movement into sediments, the stratabound Pb-Zn deposit are formed. Furthermore, the negative delta value ranges(δ34S) from -0.6 ‰ to -20.4 ‰ that have been extracted by galena can be an evidence of bacterial sulfate reduction in a subsidence sedimentary basin. In conclusion, based on field, mineralogical, fluid inclusion and sulfur isotope evidence, we propose that Gardaneshir Pb-Zn deposit is a stratabound carbonate hosted of Mississipi Valley Type(MVT).
Original Research Paper
Exploration and Mining
Iraj Rahmani; Erfan Sadeghi; Mohammad Reza Nikoodel
Abstract
Sedimentary rocks are the most common rocks exposed on the Earth’s surface and most of the civil structures are located on them, so the identification of these rocks have great importance. This recognition is more important in destructive environments such as beaches. One of the most important ...
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Sedimentary rocks are the most common rocks exposed on the Earth’s surface and most of the civil structures are located on them, so the identification of these rocks have great importance. This recognition is more important in destructive environments such as beaches. One of the most important factor on the engineering parameter results is the age of sedimentary rocks. In this study, beside the evaluation and field study of breakwaters in the southern and northern coasts of Iran, lithological and structural characteristics of materials were studied. Also, the purpose of this study was to determine and evaluate the engineering properties of stone materials based on engineering experiments to help evaluate durability and compare them with the results of field evaluation of actual rock performance. But the most important part of studies is to evaluate the effect of rock ages on the results and performance of these materials. The results show that materials with a siliceous composition such as sandstone compared to carbonate materials are the same in geological age. Also, increasing the age of rock materials (from Pleistocene to Cretaceous) causes an increase in rock density (from 1.59 to 2.45 g/cm3), reduced porosity (from 44.7 to 0.41%) and water absorption (from 29.6 to 0.21%), increase in strength parameters including increase in uniaxial compressive strength (from 5 to 111.19 MPa), increase in point load test (from 1.2 to 5.12 MPa) and increase in tensile strength (from 0.10 to 16.56 MPa) and decrease in durability due to abrasion, impact and chemical processes, including decrease in impact value (from 54.30 to 10.94%), increase in slake durability index (from 82.10 to 99.44%), a decrease in soundness (from 28.50 to 0.038 %) and a decrease in Los Angeles abrasion test (from 71.57 to 22.67%).
Original Research Paper
Tectonics
M. Kouhpeyma; M. Talebian; L. Chen; A. Ghods; M. Ghorashi
Abstract
The Kopeh Dagh and Binalud-Alla Dagh mountains are important structural elements located in the northeastern boundary of Arabia-Eurasia collision zone. Due to existence of large cities with a long history of civilization, there is a relatively rich body of data on historical seismicity in this area. ...
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The Kopeh Dagh and Binalud-Alla Dagh mountains are important structural elements located in the northeastern boundary of Arabia-Eurasia collision zone. Due to existence of large cities with a long history of civilization, there is a relatively rich body of data on historical seismicity in this area. Nonetheless, little adequate instrumental seismic data were available prior to this study. In this paper, we utilized the temporary China-Iran local seismic network data deployed in the area for 13 months. Based on this data, we determined 37 focal solutions through first motion polarity approach suggesting a combination of strike-slip, reverse and normal mechanisms. There is a significant concentration of epicenters and focal mechanisms around the eastern Alborz - Kopeh Dagh boundary along the Atrak River. The southern and western boundaries of the Binalud Mountains also show relatively high seismic activities. The Local magnitude (ML) of the events ranges from 3.5 to 4.9 with depths of up to 20 km, mostly concentrated at ~10 km. The principal stress axes and slip vectors obtained from the focal mechanisms agree well with kinematic state of main faults and tectonic regime of the area, confirming the seismogenic nature of these faults. In addition, they are consistent with right-lateral component of slip along thrust faults in eastern Kopeh Dagh and Binalud and both laft- and right-lateral motions in the central Kopeh Dagh.
Original Research Paper
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 .
