Petrology
Ashraf Torkian; Sara Damchin-Mashak; Zohreh Yarali; Maryam Souri
Abstract
The studied area is located in N-Sonqor and in the Sanandaj-Sirjan zone. Field relationships and petrographic evidence show that volcanic rocks of the north of Bashirabad comprise of trachydacite to trachyandesite (and altered basaltic trachyandesite) and in the south of this area, it consists of andesite ...
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The studied area is located in N-Sonqor and in the Sanandaj-Sirjan zone. Field relationships and petrographic evidence show that volcanic rocks of the north of Bashirabad comprise of trachydacite to trachyandesite (and altered basaltic trachyandesite) and in the south of this area, it consists of andesite to trachyte. Their texture is mainly porphyry. Geochemical data {total abundance of (Na2O+K2O), enrichment of large lithophile ion elements and rare light earth elements) indicate that these rocks belong to the alkaline series. Spider diagrams show enrichment in LREE and depletion HREE, and parallel patterns in all volcanic samples confirm their common origin. According to modeling magmatic processes, fractional crystallization, assimilation and crustal contamination have played an important role in the magma forming the studied rocks. The discriminating diagrams the tectonic setting the Bashirabad volcanic rocks indicate their subduction-related volcanic arc that was formed in an active continental margin environment with local tensions.
Economic Geology
Mostafa Esmaeili-Vardanjani; Mostafa Nazeri; Gholamreza Asgari
Abstract
Gilsonite mineralization in Shak Meydan zone as the most prone zone of Iranian gilsonite mineralization was predominantly hosted by the anidrite part of Asmari Formation (Kalhor member) and Gachsaran Formation. To find the prospect areas of gilsonite mineralization in ShakMeydan zone, the zone was divided ...
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Gilsonite mineralization in Shak Meydan zone as the most prone zone of Iranian gilsonite mineralization was predominantly hosted by the anidrite part of Asmari Formation (Kalhor member) and Gachsaran Formation. To find the prospect areas of gilsonite mineralization in ShakMeydan zone, the zone was divided into three sub zones in which exploration studies were conducted. We first tried to determine lithologic units using remote sensing processing and to separate rock units using image processing technology. Next, we plotted a 3D structural modeling of the study zone in order to increase the depth precision and to determine the stratigraphic sequence and stratigraphy-structural adaptation. Finally, we detected structural controllers including faults and existing breaks in each sub zone and circular structures prone to translocate minerals. In the sequel, we assigned appropriate weights to applied information layers including geological, tectonic, mineral information and the results of remote sensing studies using analytical hierarchy process (AHP) based on Knowledgeable information and field studies to synthesized the exploratory data in order to introduce the prospect areas with exploration priority.
N. Mousavi; J. Ebbing; V. Ebrahimzadeh Ardestani
Abstract
We apply two forward methodologies in order to study density and susceptibility structure of the crust and upper mantle. The study area is a profile crossing the Zagros collision zone located as margin of Eurasia-Arabia converging plates. Gravity modeling focusing on lithospheric structure is performed ...
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We apply two forward methodologies in order to study density and susceptibility structure of the crust and upper mantle. The study area is a profile crossing the Zagros collision zone located as margin of Eurasia-Arabia converging plates. Gravity modeling focusing on lithospheric structure is performed in thermodynamic framework in which chemical composition is important and provides an understanding of deep layers in lithosphere like Moho and Lithosphere-Asthenosphere Boundary. Results on the crustal thickness show minimum values beneath the Arabia Platform and Central Iran (42–43 km), and maximum values beneath the Sanandaj Sirjan zone (SSZ; 55–63 km). Results on the lithosphere thickness a long profile also indicate that the Arabian lithosphere is approximately 220 km thick, toward North West of Iran especially below the Central Iran rises up to 90 km. In the profile (central Zagros), lithosphere thinning occurs in wider region, from the Zagros fold thrust belt to the Sanandaj Sirjan zone. Our results are based on application of average Proterozoic mantle compositions in modeling beneath the Arabian Platform, Mesopotamian Foreland Basin and Iranian Plateau. After rough estimation of upper crust via integrated modeling by elevation, gravity and geoid data, the distribution of density and magnetic susceptibility values allows us to perform a study in crustal scale. Afterwards, determination of the homogenous blocks with the same density and susceptibility, the geometry to different crustal layers including sediments, upper, middle and lower crust deep to Moho boundary were refined in crust-scale study based on regional model in lithospheric scale. Presence of Main Zagros Fault is a bold point in our modeling which leads to better fit of gravity data.
K. Habibi; M. Behzadfar; A. Meshkini; S. Nazari
Abstract
Due to its geographic position and located on the World earthquake belt; Iran is always under threat from earthquakes and several shakes are recorded every year all over the country. The most recent earthquake with 6.8 degree magnitude on the Richter scale hit the city of Bam in 2003 and caused large ...
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Due to its geographic position and located on the World earthquake belt; Iran is always under threat from earthquakes and several shakes are recorded every year all over the country. The most recent earthquake with 6.8 degree magnitude on the Richter scale hit the city of Bam in 2003 and caused large losses of human life and infrastructure. The 2003 Bam earthquake, with more than 30,000 casualties and 10,000 injuries, was the most Destructive earthquake in the current century in Iran. We aim to recognize the main reasons causing these deterioration problems. To this end, we first conceptualize thirteen physical-spatial factors. These factors are analyzed using fuzzy logic and IHPW (Inverse Hierarchy Process Weight) within Geographical Information System. We also attempt to identify the Correlation coefficient analyses between urban vulnerability and damage using Fuzzy logic and GIS. In statistics, correlation and dependence are any of a broad class of statistical relationships between two or more random variables or observed data values. With respect to the covariance between two variables (urban vulnerability map and damage post earthquake) the correlation coefficient is calculated 0.59. The results of the model as applied to the structures of the city of Bam illustrate that a fuzzy approach is a basic tool that can be used to identify urban vulnerability and damage post earthquake incident. Its application to the problem assists in unifying relevant theories and practices.
S. Salehi Rad; S. Sherkati; F. Taati Qoaryem; M. H. Noroozi
Abstract
The Paleozoic sediments are noteworthy for many of petroleum geologists to research within Arabian Plate during last decades. Significant values of oil and gas was generated from the Silurian source rock in this area. This source rock has been modeled by commercial software's (PetroMod and Genex) in ...
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The Paleozoic sediments are noteworthy for many of petroleum geologists to research within Arabian Plate during last decades. Significant values of oil and gas was generated from the Silurian source rock in this area. This source rock has been modeled by commercial software's (PetroMod and Genex) in Saudi Arabia and its maturity proportion determined in various locations. Maturity proportion of this source rock was not characterized truly in Persian Gulf and Zagros foreland basin. Here used geological well data of three drilled wells that one's was penetrated to the Silurian shale (Sarchahan Formation) in Persian Gulf to model and used PetroMod-1D software. These well modeling results and the Saudi Arabia results show that the rate of maturity trend for Silurian shale has increased from Saudi Arabia to Iran, so that the shale is in the recognized gas window in Persian Gulf and over-mature in some part of ZagrosBasin. In Arabian Plate basemental lowlands and highlands exist at the Pre-Cambrian time, therefore cause the maturity of this shale in older highlands than the lowlands area.
M. Rezaei; A. Sargezi
Abstract
Over-exploitation from Goharkuh plain aquifer, southwest of Zahedan, resulted in water table drawdown. In order to assessing the effect of artificial recharge, numerical model of groundwater flow of the aquifer was developed. Well loges, hydrogeologic parameters, pizometric heads and results of pumping ...
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Over-exploitation from Goharkuh plain aquifer, southwest of Zahedan, resulted in water table drawdown. In order to assessing the effect of artificial recharge, numerical model of groundwater flow of the aquifer was developed. Well loges, hydrogeologic parameters, pizometric heads and results of pumping tests were used in this study. The flow model is well calibrated and used to simulate future water level fluctuations. Steady state condition has been considered in January of 2003 because of low fluctuation in groundwater level in this period. The Sensivity analysis related to a few parameters and verification for period of February of 2004 to February of 2005 has performed. The results indicate that groundwater level is reducing in Goharkuh plain aquifer. Maximum drawdown occurs in the east part of the aquifer. Aquifer reaction has been assessed by definition of different scenarios to identify the best location for artificial recharge. Based on the result, the north part of the aquifer (close to pizometer P9) is the best location for performing artificial recharge.
P. Garaei; K. Soleimani; S.R. Mousavi; A. Kavian
Abstract
In basins of the northern part of Iran, combination of natural and human factors has intensified landslide and related numerous damages. The investigation importance of this phenomena and effective factors of landslide occurrence and also determining susceptible zones it order to preventing and avoiding ...
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In basins of the northern part of Iran, combination of natural and human factors has intensified landslide and related numerous damages. The investigation importance of this phenomena and effective factors of landslide occurrence and also determining susceptible zones it order to preventing and avoiding its effects is required. At the beginning, of this research after field investigation, review of previous works in similar Lajemrood basin and using questionnaire, were recognized primary effective factors on landslide occurrence. Thin preparing effective factors maps in Geographic Information System. In order to quantifying the factors and weighting them, landslides percentage in different units was determined. For statistical analysis of multiple regressions the stepwise method was used which concluded with ignoring the elevation factor as regional model. Finally, geology, land use, slopes and distance from the road has the most effects on landslides. For evaluation of the accuracy of this model, neighboring basing (Varakee basin) with similar characteristics was chosen. The results have indicated that the most recorded area landslides in Varaki basin occurred in high and high hazard zonation. Thus, it can be concluded that presented model can be used for the study area.
A. R. Sayadi; M. Yavari; N. Solgi
Abstract
Exploration projects need considerable investments. These projects are associated with high techno-economical risks. Therefore, Evaluation of exploration potential is necessary. It is determined in primary stages of exploration whether the deposit reserve is not economic or the ...
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Exploration projects need considerable investments. These projects are associated with high techno-economical risks. Therefore, Evaluation of exploration potential is necessary. It is determined in primary stages of exploration whether the deposit reserve is not economic or the grade is less than normal grade, and it may be decided to stop the project. The minimum acceptable target reserve is known as a criterion for determining the economic potential of deposit regarding to techno-economical environment of project. In this research a new model is proposed for determining minimum acceptable target reserves in gold projects. This model is verified through the economic filed data from Zarshpran gold mine. The graph of grade versus tonnage and internal rate of return versus tonnage are demon stared through Excel software. The results of this research could be used as powerful decision making tools in gold exploration projects.
