فهرست مطالب

  • Volume:9 Issue:1, 2019
  • تاریخ انتشار: 1397/10/11
  • تعداد عناوین: 12
  • Jafar Hassanpour *, Sadegh Esmaeili Vardanjani, Akbar Cheshomi, Jamal Rostami Pages 1-20
    The Chamshir water conveyance tunnel (CWCT) with a length of 7.4 km and boring diameter of 5.3 m is excavated using a refurbished single shield TBM, initially designed to work in hard rock formations. This study focuses on engineering geological issues, which are important for checking the suitability of this machine and proposing required modifications for improving its performance in soft rock. The main objective of the investigation was to predict geological problems and risks associated with TBM tunneling in the given ground conditions and to examine the ability of the selected TBM to overcome the anticipated challenges. Geotechnical parameters that could affect TBM operation are described in this paper. These parameters include the engineering geological and hydrogeological properties of the rock units, rock mass boreability and abrasivity, and assessment of geological problems (clogging potential, swelling, abrasive ground, unstable tunnel face and water inflow). Estimated tool wear in this project is also discussed using a new special prediction model, and the results are compared with actual disc cutter consumption in the excavated section of the tunnel. The actual observations in the first 1500 m of the tunnel indicate the validity of the assessments in the related engineering geological units.
    Keywords: TBM selection, Geological problem, Clogging, Tool wear, TBM performance
  • Mostafa Moradi, Reza Muossavi Harami *, Asadollah Mahboubi, Mohammad Khanehbad Pages 21-41
    The present study focuses on facies analysis and the reservoir characteristics of the Asmari Formation in the Aghajari oilfield (located in the Zagros fold-thrust belt, southwest Iran), and how they are linked to depositional environments and reservoir characteristics. This formation consists of about 380 m carbonates with some siliciclastic intercalations. Based on the integration of 1200 m of core description and petrographic analyses of 2500 thin sections, 9 carbonate and 1 evaporite microfacies along with 2 siliciclastic petrofacies were identified. Facies analysis shows that the Asmari Formation sediments were deposited in a homoclinal carbonate ramp within open marine (facies association A), shoal (facies association B), restricted lagoon (facies association C), tidal flat (facies association D), and beach (petrofacies E) environments. Macroscopic and microscopic studies reveal that the main porosity types include interparticle, growth framework, vuggy, intercrystaline, moldic and fracture. Based on Routine core analysis (RCA), porosity of the studied reservoir varies from 0.001 to 25.8%, with an average of 12.5%. The permeability ranges from zero to 1514 mD with an average of 94.27 mD. There is a good relationship between trend of mercury injection capillary pressures (MICP) and depositional environment. Therefore, facies deposited
    Keywords: Asmari Formation, Depositional Facies, Mercury injection, Zagros basin
  • Seyed Hamid Vaziri *, Eduard G. Reinhart, Jessica E. Pilarczyk Pages 43-63
    Extreme coastal inundation associated with the 2004 Indian Ocean and 1945 Makran tsunamigenic-earthquakes highlight the risk of tsunamis to coastlines of the northern Oman Sea. Foraminifera have been used as indicators of paleotsunamis in the past where allochthonous tests, found in low-energy environments such as in coastal lagoons, ponds, and marshes, indicate marine overwash. In this study, we constrain the modern distributions of foraminifera from coastal Iran so that they may be used to identify and interpret (e.g. assess provenance) paleotsunami deposits in the geologic record. We collected surface sediment samples from sixteen sites within the study area from Chabahar to Gawater Bays on the Makran coast of Iran, selecting locations impacted by the 1945 Makran tsunami. Foraminifera obtained from these locations are dominated by intertidal, subtidal, and supratidal species, with minor abundances of planktic taxa. Samples collected from study locations are characterized by abundances of iron-stained and heavily corroded (e.g. edge rounded and pitted) individuals. Cluster analysis was used to determine three foraminiferal assemblages within the Makran coastal zone: subtidal, intertidal and supratidal. Characterizing modern distributions of foraminifera along the Makran coast of Iran will aid in identifying the provenance of older overwash deposits previously identified in this region
    Keywords: Foraminifera, coastal sediments, paleotsunami, Makran, Oman Sea
  • Oliver Hampe *, Vachik Hairapetian, Majid Mirzaie Ataabadi, Zahra Orak Pages 65-79
    In this study we present the first description of a mysticete skeleton from the late Tortonian to Messinian greyish-green marl of the Coastal Makran, south of Negour in Chahbahar County, Sistan and Baluchestan Province. This specimen is neither completely excavated, nor completely prepared, and therefore all our findings are preliminary. The identifiable components of this fossil thus far consist of an excellently preserved cranium, both dentaries which are partially obscured by the cranium and matrix, a partial vertebral column with a minimum of 15 vertebrae, and one flipper element. Preliminary evaluation of the cranium reveals some morphological similarities with that of the living blue whale, Balaenoptera musculus but also with “Megaptera” miocaena from the Tortonian of California (former E Pacific) of which the taxonomic status is still unclear. The new fossil specimen has both modern and ancient rorqual characteristics, making the proper documentation of its anatomy of particular evolutionary importance.
    Keywords: upper Miocene, Coastal Makran, cranium, Balaenopteridae, Iran
  • Morteza Tabaei *, Shamsollah Ayoubi, Alireza Aghaei Pages 81-87
    This study was conducted for palynological investigation of recent deposits from east Isfahan in order to reconstruct past environmental conditions of this region. Segzi area is located in 30 km east Isfahan and Rangideh area is 65 km in south east Isfahan. In these areas it was seen, in depth of soil profile, dark layers containing organic matters. Soil samples were taken from five points and different depth of profiles and after preparation, palynological studies were conducted on them. The results of Palynological and Paleontological investigations on Segzi area indicated presence of different aquatic plants species and also shell of gastropods.The results showed that this region during cold and semi-glacial periods of young Dryas had received higher level of water than present due to increased effective moisture and has formed a swamp. Palynological studies on buried Rangideh paleosols show microfossils such as Dinoflagellate and Micrysteridium which indicated lake and marine environments. The Rangideh was influenced by further water of Gavkhouni, compared to Segzi area.
    Keywords: ‍Palynology, Paleoenvironment, Organic matter, Gavkhouni swamp, Isfahan
  • Zahra Hosseini Asgarabadi, Saeed Khodabakhsh *, Hassan Mohseni, Nasrollah Abbassi, Galen Halverson, Thi Hao Bui Pages 89-109
    Rhythmical alternations between limestone and marls characterize the Pabdeh Formation, southwestern Iran. Three intervals of these rhythmites were studied using sedimentary, petrography and geochemical parameters analysis, to unravel the possible mechanisms responsible for the origin of these rhythmites. The microfacies analysis reflects calm deep-water sedimentation that were interrupted by sporadic traction currents from shallow-marine. The geochemical analysis indicates the primary difference between limestones and marls in interval 1. However, for the intervals 2 and 3, there is no significant difference in the geochemical results between intercalated lithologies. The isotope data (δ18O and δ13C) for limestones and marl rhythms compared with Eocene marine calcite show post depositional alteration. Limestone–marl alternations in the interval 1, therefore, originated from the cyclic changes in siliciclastic input by shallow-water derived currents (probably turbidity currents). However, for the intervals 2 and 3, although the field observations (such as extensive lateral continuity of individual beds and sharp contact between different lithologies) and some of the sedimentological parameters such as existence of the microfossils with similar preservation quality, suggest the primary rhythm as a major mechanism, the geochemical data do not strongly support this conclusion.
    Keywords: Pabdeh Formation, Stable oxygen, carbon isotope, Zagros basin, limestone–marl alternations
  • Farid Moore, Farideh Amini Birami *, Behnam Keshavarzi, Maryam Kamali Pages 111-124
    Maharlu Lake, located in the SW of Iran, has acted as a sink for various wastewater discharges in the last few decades. This study aimed at assessing potentially toxic elements (PTEs) distribution in sediment, surface and pore water samples of Maharlu Lake. To achieve that, the samples were collected from each compartment and the total concentration of PTEs (Al, Fe, Sc, Cr, Co, Ni, Zn, As, Sb, Cu, Pb, Mn, V, Cd, and Mo) analyzed by inductively coupled plasma - optical emission spectrometry (ICP-OES). Based on enrichment factor (EF) analysis the lake sediments were categorized as: minimally enriched with Sb, Co, Zn, V, Cu, Pb, As, Mn, Fe, Al and moderately enriched with Mo, Ni, Cr, and Cd. Analysis of contamination factor (Cf) and potential ecological risk factor (Er) of PTEs in sediment samples showed that there was low to moderate level of contamination. The sediment-water partition coefficients (Kd for PTEs in both water groups decreased in the order of Fe> Al>Mn>Zn>Pb>Mo>Sb>Cd. The low value of Kd (log Kd
    Keywords: pore water, potentially toxic elements, Maharlu Lake, sediment contamination, partition coefficient
  • Mohammad R. Ghassemi *, Eduardo Garzanti Pages 125-140
    This article provides a background for scientists interested in a general overview of the geology and geomorphology of Turkmenistan. The basement of Turkmenistan is a complex amalgamation of arc-related terranes developed in the Asiatic and northern Paleotethys oceanic domains during Late Paleozoic to Triassic times. A major part of the country coincides with the Turan Platform, where a thick sedimentary succession accumulated between Late Paleozoic and Cenozoic. Sedimentation rates culminated during Middle Jurassic times, being more eminent in the Kopeh-Dagh Province to the south due to backarc extension in remote regions of the Neotethys subduction zone. Closure of the Neotethys, and collisional events in the regions to the south resulted in inversion of the tectonic regime into a compressional setting in Early Cenozoic. The Caspian Province in western Turkmenistan recorded a geological and tectonic history very similar to that of the South Caspian Basin in Cenozoic times. Major gas and oil fields have developed in different petroleum systems of the Turan and Caspian Provinces. Dynamics of the Karakum desert and evolving drainages across it have a major bearing on the geomorphology and environment of Turkmenistan. Major structural features of the country are described, and attractive geological features are introduced.
    Keywords: Turkmenistan, Turan platform, Amu-Darya river, Kopeh-Dagh, geology
  • Mohammad Ghasem Fakhari, Hosein Hashemi * Pages 141-149
    Automatic processes on seismic data using pattern recognition is one of the interesting fields in geophysical data interpretation. One part is the seismic object detection using different supervised classification methods that finally has an output as a probability cube. Object detection process starts with generating a pickset of two classes labeled as object and non-object and then selecting a set of attributes that are inputs to a classifier. As a crucial step before classification, a feature extraction algorithm shall be implemented to transfer data from input space to feature space resulting in dimensionality reduction. In this paper, two feature extraction methods Principal Component Analysis (PCA) and Fisher Discriminant Analysis (FDA) in seismic object detection are compared. It is aimed to study fluid migration pathways in the North Sea and SVM classifier is used for classification thereafter. Finally, the obtained results show that in FDA classification error is less than PCA. The second and most important result is posterior probability in physical domain that in FDA is better and more interpretable than PCA.
    Keywords: Seismic Object Detection, Gas Chimney, Fisher Discriminant Analysis, Fluid Migration, Gas Pockets
  • Mousa Zohrabzadeh, Hossain Rahimpour, Bonab *, Mohsen Aleali Pages 151-167
    Detecting karstification processes in hydrocarbon carbonate reservoirs is important because of their porosity, permeability and also the risk associated with their drilling. A very useful technique to locate buried karsts is 3D seismic. In this research, seismic frequency decomposition (spectral decomposition) and seismic inversion techniques used to identify these sub-surface diagenetic features that control quality of the Asmari reservoir of the Kupal oil field. The results point to numerous buried karstified features in the upper Asmari which can be regarded as the main targets for reservoir development. According to seismic inversion, the karstic interval (mainly channel) have lower seismic acoustic impedance, and at the same time higher effective porosity. Also, numerous geological evidence such as drilling fluid loss, tidal and supratidal facies, as well as the development of fenestrate porosity, vuggy and extended vuggy porosity in the upper Asmari, all point to the meteoric diagenesis and subaerial exposure. These confirm the likelihood for paleokarsts occurrence in this part of the Asmari Formation. Therefore, the results of this research can be very useful in designing new wells in order to increase the production rate, reduce the risk and cost, when drilling new wells in the Asmari reservoir of this oil field.
    Keywords: Seismic Data, Buried karst, Reservoir Quality, Asmari Formation, Kupal oil Field
  • Fatemeh Vaez, Javadi *, Majid Mirzaie Ataabadi Pages 169-193
    Jurassic deposits are discovered in the Shahreza area, southwest of Isfahan city, central Iran. They yield plant macrofossils belonging to 22 species assigned to 17 genera of various orders such as Equisetales, Filicales, Bennettitales, Cycadales, Ginkgoales and Coniferales. According to the occurrence of Annulariopsis simpsonii, Coniopteris hymenophylloides, Cladophlebis aktashensis, Nilssonia macrophylla, and Elatides thomasii, late Early-Middle Jurassic age is suggested for this assemblage. The relative abundance of Filicales, Coniferales, and Cycadales are 50%, 27.19%, and 8.77%, respectively. Although Iran was located in a humid and warm temperate biome during the Middle Jurassic, the flora of Shahreza area indicates that it occurred at various environments: upland, wetter/drier lowland, river and coastal with temperate and humid climate. Moreover, 16 miospore species belonging to 13 genera, and seven dinocyst species assigned to three genera were identified from the studied area. Therefore, it is concluded that Shahreza reflects a coastal plain along a shallow water environment where plant macrofossil remains and miospores were sedimented.
    Keywords: Jurassic, Plant macro, microfossils, Shahreza, Iran
  • Hossein Sabbaghiyan *, Mohammadreza Aria, Nasab Pages 195-202
    A Mississippian miospore assemblage has been recorded from well A in the Persian Gulf in Iranian offshore, for the first time. Fifteen species of spores have been recognized in the Early Carboniferous assemblage of this well which the most important of them are: Spelaeotriletes arenaceus, Aratrisporites saharaensis, Spelaeotriletes balteatus, Spelaeotriletes triangulus and Radiizonates arcuatus. Comparing this assemblage with their coevals from the North Africa, Middle East, western Australia and South America reveals a very close similarity indicating the Gondwanic nature of the assemblage. Also, the Carboniferous strata in this area can be correlated with the Berwath Formation in Saudi Arabia. Based on the palynological data two hiatuses have been rcognized at the base and top of the Carboniferous strata.
    Keywords: Carboniferous, Mississippian, Gondwana, miospore, Persian Gulf