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Three-dimensional inversion of magnetic data in the simultaneous presence of significant remanent magnetization and self-demagnetization: example from Daye iron-ore deposit, Hubei province, China.
- Source :
-
Geophysical Journal International . Oct2018, Vol. 215 Issue 1, p614-634. 21p. - Publication Year :
- 2018
-
Abstract
- Natural remanent magnetization and self-demagnetization on high-susceptibility bodies are two important factors affecting magnetic data inversion. We propose a framework for the inversion and interpretation of magnetic anomalies, in which significant remanent magnetization and self-demagnetization are present simultaneously. The framework is based on the assumptions that the external applied field and internal self-demagnetization field are uniform and the deflection of self-demagnetization in the total magnetization direction is negligible. First, the magnetization vector distributions are obtained from magnetic data by estimating the magnetization direction, then inverting for the magnetization intensity distribution, using the inferred magnetization direction as a constraint. Based on a priori information about the Koenigsberger ratio derived from petrophysical measurements, the direction and intensity of the remanent magnetization are obtained. The self-demagnetization factor is then computed using the finite volume method. Finally, the true-susceptibility distribution is achieved by correcting for the self-demagnetization effect. The method is first applied to synthetic magnetic data produced by a prism-shaped source model that has significant remanent magnetization and high susceptibility. In a case study of the Daye iron-ore deposit, Hubei province, China, the true susceptibility and remanent magnetization are reconstructed. The remanence direction information reveals that local geological activities such as synclines and faults lead to changes in the remanence directions at different local deposits. [ABSTRACT FROM AUTHOR]
- Subjects :
- *MAGNETIZATION
*DEMAGNETIZATION
*IRON ores
*SYNCLINES
*MAGNETISM
Subjects
Details
- Language :
- English
- ISSN :
- 0956540X
- Volume :
- 215
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Geophysical Journal International
- Publication Type :
- Academic Journal
- Accession number :
- 132600650
- Full Text :
- https://doi.org/10.1093/gji/ggy299