GEOSCAN, résultats de la recherche


TitreFractal magnetization of continental crust
AuteurPilkington, M; Todoeschuck, J P
SourceGeophysical Research Letters vol. 20, no. 7, 1993 p. 627-630,
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 28992
Documentpublication en série
Mediapapier; en ligne; numérique
Sujetscroûte continentale; aimantation; méthodes analytiques; susceptibilité magnétique; établissement de modèles magnétiques; méthodes statistiques; géophysique; géomathématique
Illustrationsformulae; models
Diffusé2012 12 07
Résumé(disponible en anglais seulement)
Many geophysical variables exhibit fractal or at least scaling behaviour, notably in having power spectra proportional to some power of frequency. Power spectra of magnetic susceptibility logs from boreholes are proportional to spatial frequency f-2 for wavelengths from 0.1 to 100 m. If the power spectrum of the susceptibility or magnetization of the crust is known then the power spectrum of the magnetic field at the surface can be calculated. We show that if magnetization is scaling with a single scaling exponent then the observed f-3 power spectra of aeromagnetic data implies a three-dimensional f-4 susceptibility distribution for length scales of 1 to 1000 km. One way to reconcile the two results is to introduce anisotropy in the form of a f-4 variation for the horizontal direction and f-2 for the vertical.