1 دانشآموخته کارشناسی ارشد ژئوفیزیک، مؤسسة ژئوفیزیک دانشگاه تهران، ایران
2 دانشیار، گروه فیزیک زمین، مؤسسة ژئوفیزیک دانشگاه تهران، ایران
3 عضو هیأت علمی دانشگاه آزاد اسلامی واحد لاهیجان، ایران
4 کارشناس ارشد، سازمان انرژی اتمی ایران
عنوان مقاله [English]
Some new statistical techniques are gaining favor and momentum in the separation of background concentration values from anomalous values in determining the economics of extraction of Uranium deposits. In exploration of minerals and feasibility of
exploration procedures, old conventional methods are replaced by new ones which have roots in natural distribution patterns. One of the methods is usage of fractal geometry in the separation of various statistical populations used in these studies such as different background values, threshold limits and anomalous values.
In this paper, in the first step, separation of anomaly values has been performed by means of classical statistics. Then the tables of frequency distribution of Uranium, Thorium and Potassium have been classified, and the frequency distribution histograms have been plotted. The statistical parameters of these three elements have then been estimated. Then separation of anomaly values has been performed based on dispersion around the average. In the second step, separation of anomaly values has been performed by using fractal method based on concentration-area curves.
In this work a comparison of classical statistical method has been made with fractal techniques of separation and grouping of the various values. The data used in this study were the airborne acquired geophysical data of the area which has been based on gamma ray emission of radioactive nuclides present in natural earth’s environment. At the first stage of the study the statistical parameters such as mean, mode, median dispersion of the mean, standard deviation, skewness, kurtosis of the data were plotted and the relative values were calculated. At the second stage, using fractal geometry techniques, concentration-area mathematical model of fractal curves were drawn after the interpolation of X, Y and Z digitized data had been constructed. On the basis of the concentration-area model the fractal dimensions were calculated and separation of various statistical populations was made on the basis of tangent values drawn to the fractal curves. The trends of variations in various statistical populations representing the interpreted concentration values were made using the above two procedures, and the advantages and disadvantages of the methods are described. Finally, based on both classical statistics and fractal methods, anomaly maps are plotted in which the anomaly values are separated from background values for all three radioactive elements of Uranium, Thorium and Potassium.