Rock magnetic investigation of possible sources of the Bangui magnetic anomaly

•We investigate the source of the Bangui magnetic anomaly.•We use satellite and ground magnetic field measurements.•We measure magnetic susceptibility and natural remanent magnetization on samples.•Few surface rocks have the required total magnetization to account for the BMA.•The whole crust beneat...

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Bibliographic Details
Published in:Physics of the earth and planetary interiors 2013-11, Vol.224, p.11-20
Main Authors: Ouabego, M., Quesnel, Y., Rochette, P., Demory, F., Fozing, E.M., Njanko, T., Hippolyte, J.-C., Affaton, P.
Format: Article
Language:English
Subjects:
Applied geology
Banded iron formation
Bangui magnetic anomaly
Earth
Earth Sciences
Environmental Sciences
Formations
Geological source
Geology
Geophysics
Global Changes
Magnetic anomalies
Magnetic fields
Magnetic permeability
Magnetization
Modelling
Physics
Planetology
Rock
Sciences of the Universe
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Summary:•We investigate the source of the Bangui magnetic anomaly.•We use satellite and ground magnetic field measurements.•We measure magnetic susceptibility and natural remanent magnetization on samples.•Few surface rocks have the required total magnetization to account for the BMA.•The whole crust beneath the BMA is strongly magnetic. The Bangui magnetic anomaly (BMA) is the largest lithospheric magnetic field anomaly on Earth at low latitudes. Previous studies investigated its geological source using constraints from satellite and ground magnetic field measurements, as well as from surface magnetic susceptibility measurements on rocks from the Panafrican Mobile Belt Zone (PMBZ). Here we combine magnetic field data modelling and rock magnetic property measurements (susceptibility and natural remanent magnetization, NRM) on many samples from this PMBZ and the surrounding formations. It reveals that NRM is a significant component of the total magnetization (Mt) of the BMA source, which reaches 4.3A/m with maximum thicknesses of 38 and 54km beneath the western and eastern parts of the BMA. Only the isolated and relatively thin banded iron formations and some migmatites show such Mt values. Thus we suggest that the thick BMA source may be composed either by overlapped slices of such metamorphic rocks, or by an iron-rich mafic source, or by a combination of these two geological structures.
ISSN:0031-9201
1872-7395
0031-9201
DOI:10.1016/j.pepi.2013.09.003