Alkaline character of Eocene volcanism in the middle part of central Iran and its geodynamic situation     

Sayed Mehdi Amidi  Mohammad Hashem Emami  Robert Michel 《International Journal of Earth Sciences》1984,73(3):917-932

Alkaline volcanic rocks, sometimes feldspathoid bearing, appear in variable stratigraphic positions within the Eocene of the middle part of Central Iran. No magmatic zonation and no K₂O enrichment in both time and space can be found in this volcanic sequence. These facts together with other geochemical and geological features of the Iranian Eocene provinces do not agree with a volcanism related to a subduction zone model.Reversely, a rift model may be applied for the interpretation of the origin of Eocene volcanic rocks and their geodynamic situation. The emissions of alkaline magma are linked with rhythmic opening of a rift zone during Eocene.A mutual contamination between a basaltic magma and a bulky palingenetic acid magma is responsible for the few volcanic rocks with calc-alkaline trend.

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Zusammenfassung Alkali-Gesteine, die manchmal Feldspatoide enthalten, treten in verschiedenen stratigraphischen Stellungen innerhalb des Eozäns des Zentral-Irans auf.In diesen Vulkaniten ist keinerlei magmatische Zonierung und insbesondere keine systematische Variation der Kaligehalte festzustellen. Diese und andere geologische und geochemische Argumente sprechen gegen eine Deutung als Paläosubduktionszone.Als Alternative bietet sich das Modell der Öffnung eines Grabens an: der Alkali-Vulkanismus steht in Zusammenhang mit den verschiedenen Phasen der Entstehung und Entwicklung eines Rifts während des Eozäns.Die seltenen Vulkanite kalk-alkalischer Zusammensetzung erklären sich durch Mischung der Magmen von Alkali-Basalten mit den bedeutenden anatektischen Magmen.

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Résumé Des roches alcalines, éventuellement à feldspathoïde, existent à des niveaux et dans des secteurs variés de la séquence volcanique éocène de la partie médiane de la zone de l'Iran Central; par ailleurs, dans cette série, on n'a pu mettre en évidence ni zonation magmatique, ni enrichissement en K₂O. Ces faits, joints à d'autres caractères géochimiques et géologiques des provinces éocènes de l'Iran, sont en désaccord avec un volcanisme lié à une zone de subduction.En revanche, un modèle de rift peut être appliqué pour interpréter l'origine des volcanites éocènes et leur situation géodynamique. Les émissions de magma alcalin sont en effet en relation avec l'ouverture rhythmique d'une zone de rift pendant l'Eocène.Quant aux rares roches à tendance calco-alcaline, elles résultent d'une contamination mutuelle entre un magma basaltique et un important magma acide palingénétique.

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Syn-depositional continental rifting of the Southeastern Neo-Tethys margin during the Albian–Cenomanian: evidence from stratigraphic correlation     

Amin Navidtalab  Mehdi Sarfi  Amirhossein Enayati-Bidgoli  Mohsen Yazdi-Moghadam 《International Geology Review》2020,62(13-14):1698-1723

ABSTRACT

Albian–Cenomanian successions (Kazhdumi and Sarvak formations) represent remarkable variations in thickness, facies, fauna, and environments throughout the Zagros area. In the Coastal Fars (Charmu section), sedimentological and paleontological data evidence an intrashelf, with depths of 10s–100s m, surrounded by a shallow carbonate platform. Due to its depth, deposition of sequences in this setting has been controlled by eustatic sea-level changes rather than eurybathic changes, and several condensation episodes occurred related to marine transgressions. These observations are different from those in the adjacent sections in the Coastal Fars which recorded subaerial exposures instead. Combined with previous studies, this study denotes several intrashelf basins enclosed by a shallow carbonate platform on the southeastern margin of the Neo-Tethys during the Albian–Cenomanian. Development of intrashelf basins corresponds to basement faults in the Fars Salient. Likely, an extensional tectonic regime associated with a rifting event created horst–graben architecture by exerting extension along the basement faults and reactivating salt structures. Deposition on these troughs and highs led to the facies and thickness variations of the concomitant sequences. Development of several intrashelf basins on the southeastern margin of the Neo-Tethys indicates that syn-depositional continental rifting event could occur during the Albian–Cenomanian, prior to the tectonic inversion around the earliest Turonian.  相似文献   

Genetic connectivity of the coral‐eating sea star Acanthaster planci during the severe outbreak of 2006–2009 in the Society Islands,French Polynesia          下载免费PDF全文

Nina Yasuda  Coralie Taquet  Satoshi Nagai  Terutoyo Yoshida  Mehdi Adjeroud 《Marine Ecology》2015,36(3):668-678

Occasional population outbreaks of the crown‐of‐thorns sea star, Acanthaster planci, are a major threat to coral reefs across the Indo‐Pacific. The presumed association between the serial nature of these outbreaks and the long larval dispersal phase makes it important to estimate larval dispersal; many studies have examined the population genetic structure of A. planci for this purpose using different genetic markers. However, only a few have focused on reef‐scale as well as archipelago‐scale genetic structure and none has used a combination of different genetic markers with different effective population sizes. In our study, we used both mtDNA and microsatellite loci to examine A. planci population genetic structure at multiple spatial scales (from <2 km to almost 300 km) within and among four islands of the Society Archipelago, French Polynesia. Our analysis detected no significant genetic structure based on mtDNA (global F_ST = ?0.007, P = 0.997) and low levels of genetic structure using microsatellite loci (global F_ST = 0.006, P = 0.005). We found no significant isolation by distance patterns within the study area for either genetic marker. The overall genetically homogenized pattern found in both the mitochondrial and nuclear loci of A. planci in the Society Archipelago underscores the significant role of larval dispersal that may cause secondary outbreaks, as well as possible recent colonization in this area.  相似文献   

Seismic risk assessment of the 3rd Azerbaijan gas pipeline in Iran   总被引：1，自引：1，他引：0  

Mehdi Mousavi  Mostafa Hesari  Alireza Azarbakht 《Natural Hazards》2014,74(3):1327-1348

A comprehensive seismic risk assessment has been performed for the existing route of the 3rd Azerbaijan natural gas buried pipeline in Iran. The major active seismic sources along the pipeline were identified and the geometrical parameters as well as the seismicity rates were determined. The seismic hazard assessment of the ground vibrations along the pipeline was performed in the framework of the Probabilistic Seismic Hazard Analysis using the CRISIS 2007 software. All of the components of the gas pipeline along the route were identified and the corresponding fragility functions are established through the methodology described in the HAZUS guideline (HAZUS MH MR4 Technical manual 2007 Department of homeland security emergency. Preparedness and Response Directorate, FEMA). A detailed cost analyses was taken into consideration based on the expert opinions in the National Iranian Gas Company, in order to provide more practical loss model for the pipeline route. Also, a simple method is suggested in order to account for the vent gas in the total loss estimation. The spatial analysis of the hazard function layer in combination with the loss model layer, in Geographical Information System  (GIS) platform, reveal the financial consequences of different earthquake scenarios.  相似文献   

The efficiency of Penicillium commune for bioremoval of industrial oil     

A. Esmaeili  E. Sadeghi 《International Journal of Environmental Science and Technology》2014,11(5):1271-1276

Among all environmental contaminations, industrial oil is one of the major pollutants of soil, water, and air. There are different chemical, physical, and biological methods to remove all types of oil pollutions. One of the common biological methods is to utilize the microorganisms like yeast, fungi or bacteria. Previous studies concerning the biodegradation of an aromatic compound in industrial waste water by Aspergillus niger have been reported. In this study, we tried to identify an oil-derived microorganism and evaluate its efficacy on self-removal of industrial oil. Firstly, the strain of isolated fungus from various bulks of used oil was defined via colonial identification and DNA sequencing. Secondly, bioremoval activity of defined fungus (Penicillium commune) was evaluated using gas chromatography–mass spectrometry. The optimum conditions in biological elimination of oil including the incubation time, pH level of culture, and amount of reagents were determined. In the best condition, a removal rate of 95.4 % was obtained.  相似文献   

Soil Deformations During Casing Jacking and Extraction of Expanded-Shoe Piles,Using Model Tests   总被引：1，自引：0，他引：1  

Chang-Guang Qi  Magued Iskander  Mehdi Omidvar 《Geotechnical and Geological Engineering》2017,35(2):809-826

A small-scale 1-g transparent soil model was employed to investigate soil deformations caused by casing-assisted pile jacking of plastic tube cast-in-place concrete piles. The transparent soil was made of fused quartz and a refractive index matched blended oil. Models were sliced with a laser light sheet and digital images were employed to record jacking and extraction of the casing, allowing the use of digital image correlation to derive the generated displacement fields, non-intrusively. The effects of the shoe shape as well as use of a casing to jack the pile were investigated. It was found that under unconfined conditions, soil response to jacking is significantly affected by the pile shoe shape, with displacements adjacent to a conical shoe markedly smaller compared to a flat shoe. Moreover, casing extraction results in recovery of some of the soil deformation that takes place during pile jacking.  相似文献   

A new rating system approach for risk analysis of rock slopes     

Nassirzadeh Goorchi  Reza  Amini  Mehdi  Memarian  Hossein 《Natural Hazards》2017,91(1):75-102

In this paper, an approach is presented to analyze the stability risk of rock slopes based on a new rating system. Three factors are used to estimate the risk level of rock slopes: (1) failure probability, (2) element at risk rating, and (3) vulnerability rating. Element at risk and vulnerability ratings are both given a range from 0 to 10, and the probability of failure is varied between 0 and 1, so the risk rating ranges between 0 and 100. This risk rating can be used to determine both the quantitative and qualitative risk levels of slopes at the same time. The method is tested on the western sector of the slopes facing Songun copper plant phase III, Iran, to clarify its procedures and assess its validity. Deterministic kinematic analyses showed that the slope has a potential for circular failure. Risk assessments revealed that the risk levels of the slope in both static and pseudo-static conditions are “very low” and “high,” respectively.

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Analysis of temporal and spatial variations in groundwater nitrate and development of its pollution plume: a case study in Karaj aquifer     

Manouchehr Chitsazan  M. Mohammad Rezapour Tabari  Mehdi Eilbeigi 《Environmental Earth Sciences》2017,76(11):391

Considering the importance of groundwater resources in water-supply demands in arid and semiarid areas such as Iran, it is essential to investigate the risk of groundwater pollution. Nitrate is one of the main pollutants that penetrate into the groundwater from various sources such as chemical fertilizers, pesticides, and domestic and industrial sewage. Unfortunately currently, nitrate contamination of the aquifers is a serious problem in Iran. The Karaj aquifer is not exempted, and the nitrate pollution zone, with concentrations far beyond the permitted limit (50 mg/L), expands fast. In this paper, the long-term groundwater-quality data (from 2000 to 2013) collected from Alborz Province Water and Wastewater Company were analyzed using ArcGIS10 and statistical software, and the spatial and temporal patterns of nitrate pollution in drinking-water wells in the Karaj plain and effective parameters (such as depth to groundwater level, hydraulic gradient, land use, precipitation, and urban, agricultural and industrial wastewater) were investigated. The authors also investigated the status of nitrate concentration variation using the concepts of geostatistics, based on determinations from 62 to 194 surveyed wells with a suitable distribution across the plain. With respect to the relationship between quality parameters, hydrogeological status of the aquifer and land usage, causes of the increase in the concentration of nitrate in the water and its trend were investigated as well. Results revealed that the nitrate levels in the northern portion of the study area were the highest with maximum concentrations of 181.7 mg/L from 2000 to 2013. Based on nitrate concentration distribution maps, the levels of nitrate increased from 2006 onwards to 26–100 mg/L. Unfortunately from 2008 to 2012, a pollution zone with a nitrate water concentration of 101–150 mg/L has been observed and even a concentration of 180 mg/L has been determined. In 2000, the entire aquifer area has been drinkable but with the increase in nitrate concentration, the area with undrinkable water has expanded to 21% in 2003, 24% in 2005, 33% in 2007, 39% in 2009, 43% in 2011 and 44% in 2013. The results of this study could provide valuable information with on the status of nitrate water concentrations in the Karaj plain which demands proper strategies and qualitative approaches in the future.  相似文献   

Numerical study on static and seismic stability of breakwaters on soft granular marine deposits against deep failure     

Mehdi Veiskarami  Mir Ahmad Lashteh Neshaei  Mehran Karimpour Fard  Tina Pourramezan 《Marine Georesources & Geotechnology》2017,35(1):42-51

Marine structures which cover a wide range of offshore and onshore structures are often subjected to different external and internal forces against which a proper design should be performed. Among many, breakwaters constructed over a relatively loose agglomerate of granular soils are much prone to deep seated failure extended beneath the foundation. This type of failure has been given less attention in conventional design approaches. Stability analysis of such failures is the main subject of this research which includes both the static and the seismic stability of breakwaters over granular marine soils. As the subsoil strata in sea beds often comprise loose sand deposits, it is more convenient to assume a rather small angle of dilation, at least at failure, which certainly reduces the potential to resist geotechnical instabilities. The method of stress characteristics along with slight modifications to handle this issue has been used to assess the overall stability of breakwaters against deep seated failures. Investigations revealed that while even under static condition, there is certain potential of failure, under seismic condition, the risk is quite very high. A series of design charts are also developed presenting the factor of stability as a measure of safety against such failure.  相似文献