جستجوی مقالات مرتبط با کلیدواژه "مدل سازی دوبعدی" در نشریات گروه "زمین شناسی"

This study investigates the efficiency of different geophysical methods for detecting contaminated zones as well as hidden pipes. There are a number of geophysical techniques that can be useful and beneficial for achieving these purposes. Ground penetrating radar (GPR) and electrical resistivity methods are the most useful approaches for identifying polluted areas and buried features, causing us to utilize such methods in the area. Although GPR and electrical resistivity methods are solely effective for mapping subsurface targets, the integration of these methods might provide us valuable information and valid outcomes. In this paper, electrical resistivity and GPR surveys are conducted and acquired data are modelled to investigate the pollution leakage in the ground. To achieve this aim, a polyethylene pipe with inlet and outlet valves is considered as a tank buried underground in the geophysical test site of Shahrood University of Technology. In the first step of the study, the electrical properties of the empty pipe were measured and modelled using electrical resistivity and GPR methods. In the next step, the pipe was filled by the cupric sulfate solution and electrical measurements were performed again. In addition, the electrical properties were investigated by means of electrical resistivity and GPR methods in another area, sitting on alluvial soil, after and before injecting the cupric sulfate solution. It is worth mentioning that the measurements were performed after drying the surface which was humid due to the injection of cupric sulfate to avoid false conductivity on the ground. The designed profiles include four lines on a buried reservoir and five profiles on alluvial soil. However, the 2D modeling results and interpretation of the acquired data along with two (on the buried target) and three (on alluvial soil) survey lines are just presented in this paper. After collecting and interpreting the electrical resistivity and GPR data in the study area, the results are in the form of two-dimensional models of electrical resistivity and GPR cross sections, which have been obtained by use of RES2DINV and Prism2 softwares, respectively. The obtained results revealed that the electrical resistivity method enjoys a relatively good performance in detailed detection. It is also shown that the GPR method is not able to work properly in alluvial soils with high clay and it suffers from the unsuitability of the transmitter antenna with a frequency of 150 MHz and the destructive effect of moisture on the performance. Regarding the obtained outcomes and using electrical resistivity data, ground details such as polyethylene reservoir, loose and porous soil parts and separation of different areas according to the relative humidity in them have been revealed.

Summary For the present two-dimensional (2-D) lithospheric density-temperature distribution modeling, we have selected a north-south geo-transect cut in east of Iran from the Oman Sea to the Lut block with a length of about 800 km. As the structural domains, investigated in this paper, have mainly been created under the effect of the north-south subduction of the Arabian Oceanic Plate under the Eurasia, thus, most of these structures are approximately perpendicular to this direction. As a result, in order to avoid three-dimensional (3-D) structural effects in our 2D modeling, we have selected a profile perpendicular to the strike, which is roughly the north-south direction.
Introduction In order to avoid interpreting isolated anomaly features being located accidentally on the profile of the geoid, free air and topography data, we average the data within a width of 50 km to both sides of the profile and calculate the variance within this stripe using 5 km long steps along the profile. The resulting standard deviation is plotted as uncertainty bars. Since the lateral resolution of our data is of the order of several kilometers, therefore, we cannot reproduce small‐scale details. The generated model consists of a sedimentary layer, the upper, middle and lower crust and a lithospheric mantle layer. In order to constrain the various thicknesses, the results of previous works carried out in the study region have been used.
Methodology and Approaches Modeling carried out in this research is based on the assumption of local isostatic equilibrium and joint interpretation of gravity, geoid and topography data with temperature-dependent density. Bouguer anomaly data are mainly sensitive to crustal density distribution and decrease proportionally to the squared distance (r) from an object, whereas elevation is very sensitive to changes in density and thickness of the lithospheric mantle and the geoid undulations diminish proportionally to r−1. The data different sensitivity on distance from the object can be a good constraint on modeling lithospheric density-temperature distribution.
Results and Conclusions Because of subducting Arabian plate in Makran subduction zone, thickness of the lithosphere increase from the Oman Sea (90 km) to the Taftan-Bazman volcanic arc, with a maximum thickness (290 km) under the volcanic arc. Based on our modeling results, subduction of the oceanic crust of Arabian plate under the Makran belt starts with a very low dip angle and bends under the Taftan-Bazman volcanic arc with a relatively higher dip. There is a logical correlation between the subducted slab and the seismicity of Makran subduction zone. Because of the low dip subducting slab, there is a long distance between volcanic arc and forearc setting (~450 km). Further to the north, lithospheric thickness is reduced to the ~200 km under the Lut block which is in good agreement with earlier studies. Our integrated modelling approach reveals a crustal configuration with the Moho depth varying from ∼21 km beneath the Oman Sea, and ∼47 km beneath the Taftan-Bazman volcanic arc to about 37 km beneath the Lut block. Across the Makran subduction zone, Moho depth is increasing from the Oman seafloor and Makran forearc setting (~21 km) to the volcanic arc (∼45–50 km). Furthermore, we have found that the oceanic crust is a two layered plate and there is a thick sedimentation there to about 8-9 km.