Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
doi:10.5194/gmd-2017-44
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Methods for assessment of models
21 Apr 2017
Review status
This discussion paper is under review for the journal Geoscientific Model Development (GMD).
Ellipsoids (v1.0): 3D Magnetic modelling of ellipsoidal bodies
Diego Takahashi Tomazella and Vanderlei C. Oliveira Jr. Department of Geophysics, Observatório Nacional, Rio de Janeiro, Brazil
Abstract. A considerable amount of literature has been published on the magnetic modelling of uniformly magnetized ellipsoids since the second half of the nineteenth century. Ellipsoids have flexibility to represent a wide range of geometrical forms, are the only known bodies which can be uniformly magnetized in the presence of a uniform inducing field and are the only bodies for which the self-demagnetization can be treated analytically. This property makes ellipsoids particularly useful for modelling compact orebodies having high susceptibility. In this case, neglecting the self-demagnetization may strongly mislead the interpretation of these bodies by using magnetic methods. A number of previous studies consider that the self-demagnetization can be neglected for the case in which the geological body has an isotropic susceptibility lower than or equal to 0.1 SI. This limiting value, however, seems to be determined empirically and there has been no discussion about how this value was determined. Besides, the geoscientific community lacks an easy-to-use tool to simulate the magnetic field produced by uniformly magnetized ellipsoids. Here, we present an integrated review of the magnetic modelling of arbitrarily oriented triaxial, prolate and oblate ellipsoids. Our review includes ellipsoids with both induced and remanent magnetization, as well as with isotropic or anisotropic susceptibility. We also propose a way of determining the isotropic susceptibility above which the self-demagnetization must be taken into consideration. Tests with synthetic data validate our approach. Finally, we provide a set of routines to model the magnetic field produced by ellipsoids. The routines are written in Python language as part of the Fatiando a Terra, which is an open-source library for modelling and inversion in geophysics.

Citation: Tomazella, D. T. and Oliveira Jr., V. C.: Ellipsoids (v1.0): 3D Magnetic modelling of ellipsoidal bodies, Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-44, in review, 2017.
Diego Takahashi Tomazella and Vanderlei C. Oliveira Jr.
Diego Takahashi Tomazella and Vanderlei C. Oliveira Jr.
Diego Takahashi Tomazella and Vanderlei C. Oliveira Jr.

Viewed

Total article views: 58 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
47 6 5 58 3 2

Views and downloads (calculated since 21 Apr 2017)

Cumulative views and downloads (calculated since 21 Apr 2017)

Viewed (geographical distribution)

Total article views: 58 (including HTML, PDF, and XML)

Thereof 58 with geography defined and 0 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 24 Apr 2017
Publications Copernicus
Download
Short summary
Ellipsoids are the only bodies for which the self-demagnetization can be treated analytically. this property is particularly useful for modelling compact orebodies having high susceptibility. Here, we present a review of the magnetic modelling of ellipsoids, propose an alternative way of determining the isotropic susceptibility above which the self-demagnetization must be taken into consideration, as well as provide a set of routines to model the magnetic field produced by ellipsoids.
Ellipsoids are the only bodies for which the self-demagnetization can be treated analytically....
Share