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DETECTION OF IRON DEPOSITS BY NORMALIZED FULL GRADIENT METHOD: OJATABAD DEPOSIT, IRAN
Abstract
The Normalized Full Gradient (NFG) method was introduced in the mid of 1960s. This method generally uses for interpretation potential field data in order to detect gravity and magnetic anomalies. The NFG value represents the full gradient of the magnetic anomaly at a point divided by the average of the full gradient at the datum. The closed maxima on a NFG map indicate the occurrence and the horizontal locations of the centers of magnetic anomalies related to iron deposits. By means of this map, we can select bore-hole locations in the field. In this study, we applied the NFG method for detecting Ojatabad iron deposit (Semnan Province) and determination of its depth by means of magnetic anomalies. In this paper, after needed corrections, we draw magnetic anomalies map. In order to calculation the NFG values, a 2D algorithm is provided and the NFG value map is drown. By applying the NFG method to the Ojatabad iron deposit, using closed maxima of the NFG method alongside the other methods, showed that the magnetic anomalies are located in shallow depths ranged from approximately 10 to 80 meters. Modeling studies show that the NFG largely depends on number of terms in the Fourier series used to calculate it, and it closely related to the length and girding of the magnetic profile or the size of the study area.
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References11
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