Inversion of magnetic measurements of the CHAMP satellite over the Pannonian Basin

Abstract

The Pannonian Basin is a deep intra-continental basin that formed as part of the Alpine orogeny . In order to study the nature of the crustal basement we used the long-wavelength magnetic anomalies acquired by the CHAMP satellite. The anomalies were distributed in a spherical shell, some 107,927 data recorded between January 1 and December 31 of 2008. They covered the Pannonian Basin and its vicinity. These anomaly data were interpolated into a spherical grid of 0.5° × 0.5°, at the elevation of 324 km by the Gaussian weight function. The vertical gradient of these total magnetic anomalies was also computed and mapped to the surface of a sphere at 324 km elevation. The former spherical anomaly data at 425 km altitude continued downward to 324 km. To interpret these data at the elevation of 324 km we used an inversion method. A polygonal prism forward model was used for the inversion. The minimum problem was solved numerically by the Simplex and Simulated annealing methods; a L 2 norm in the case of Gaussian distribution parameters and a L 1 norm was used in the case of Laplace distribution parameters. We interpret that the magnetic anomaly was produced by several sources and the effect of the sable magnetization of the exsolution of hemo-ilmenite minerals in the upper crustal metamorphic rocks . ► Derivation of the total magnetic anomaly field from the CHAMP data over the Pannonian Basin and its vicinity. ► It is supposed the forward model of the source of magnetic anomalies is a triangular prismatic body which has a uniform magnetization. Its coordinates are determined by the numerical solution of an inverse problem. The applied numerical methods are the Simplex and Simulated Annealing procedures. ► Magnetic anomalies are assumed to be produced by the exsolution of the hemo-ilmenite minerals in the crust.