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Nowadays, airborne electromagnetic methods are widely used to investigate subsurface areas. One of these methods is helicopter electromagnetic method. The basis of inverse modeling of frequency-domain HEM data is to solve Mundry’s integral numerically. Various methods have been invented for numerical solution of this integral, such as Laplace transform, fast Hankel coefficients and Jacobian methods. To analyze helicopter electromagnetic data, we need inverse programs which can assist us to achieve the best or ac...

Nowadays, airborne geophysical data can be obtained in low costs rapidly. Among airborne geophysical systems to acquire magnetic, electromagnetic and radiometric data, helicopter geophysical systems play an important role in exploration of mineral deposits in large areas. In general, using airborne systems to measure electromagnetic data, we can obtain two-dimensional conductivity-depth sections, and then, a threedimensional conductivity model from the subsurface of the survey area. Consequently, the lateral and v...

Electromagnetic (EM) methods are among geophysical methods which have many various applications. Besides, EM surveys are carried out rapidly with low costs. Thus, they are being fast developed. The methods, compared to other geophysical methods, have the most various acquisition systems. EM surveys can be carried out in the land, air, sea and borehole. During 1950s in Canada, airborne EM methods, in which helicopter EM (HEM) method is also included, have assisted in mineral exploration valued more than 10 milliard...

Horizontal location and interpretation of gravity anomalies plays an important role in the detection of anomalous bodies and determination of explorative boreholes location. There are various methods for interpreting of gravity anomalies, which commonly use high-pass filters. Among these, Normalized Full Gradient (NFG) method represents the full gradient of the gravity anomaly at a point divided by the average of the full gradient at the datum. This method uses Fourier series to remove deficiencies and eliminate t...

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...