Simultaneous Interactive Magnetic and Gravity Inversion*

Abstract

Gravity and magnetic anomalies may have the same source but it is always difficult to achieve correlated solutions if interpretations are carried out separately. Therefore it is useful to invert both anomalous gravity and magnetic profiles at the same time, so that the solution mav be more constrained. Existing inversion techniques do not lend themselves equally to this kind of extension, since the parameters—such as density and susceptibility contrasts—should not be related. The algorithms more easily adaptable to simultaneous inversion are those which look for the shape and the position of anomalous bodies with constant unknown density or susceptibility contrasts. In this study, we use the generalized inverse method in the 2 1/2 D case. Parameters are the coordinates of the vertices of the polygonal cross‐sections of the anomalous bodies and both density and susceptibility contrasts of each body. The two types of profile to be processed must be superposable but may have different lengths, spacings, and coordinate origins. Both synthetic examples and field data from geologically known areas have been processed, and it appears that the simultaneous inversion technique may provide an important additional degree of control in the interactive interpretation process.

A multidisciplinary study of a syntectonic pluton close to a major lithospheric‐scale fault—Relationships between the Montmarault granitic massif and the Sillon Houiller Fault in the Variscan French Massif Central: 2. Gravity, aeromagnetic investigations, and 3‐D geologic modeling

“…Furthermore, the joint gravity and magnetic modeling constrains the geometry of a geological source both in terms of density and magnetic contrast with surrounding rocks. Therefore, taking into account measured petrophysical properties, the joint gravity and magnetic modeling tightly constrains the geological interpretation [ Menichetti and Guillen , 1983]. Though nonunique, the obtained model is compatible with both available potential field data and integrates the present‐day geological knowledge.…”

Crustal configuration of the Dharwar craton, India, based on joint modeling of regional gravity and magnetic data

“…It is useful to invert both gravity and magnetic data sets jointly so that solutions may be better constrained (Menichetti and Guillen, 1983). Therefore, assuming both the gravity and magnetic anomalies have the same source, joint modeling was performed using GM-SYS (Geosoft Inc., 2001) software to synergistically combine information compatible with both data sets.…”

Inversion of potential field data by genetic algorithms

“…Recently a number of authors have proposed a simultaneous inversion of gravity and magnetic data in order to reconstruct the shape of buried geological bodies (Menichetti and Guillen 1983;Zeyen and Pous 1993). The rationale behind this procedure is that the ambiguity inherent in the inversion of potential field data is greatly reduced when the two data sets are combined.…”