Encyclopedia of Astrobiology

Living Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James Cleaves, Daniele Pinti, José Cernicharo Quintanilla, Michel Viso

Magnetic Anomaly

  • Nicholas Arndt
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_917-3


A magnetic anomaly is a local departure in orientation or strength from the large-scale pattern of a planetary magnetic field. Stripes of alternating positive and negative polarity parallel to isochrons in the Earth’s oceanic crust record reversals of the magnetic field; they provided the first evidence of seafloor spreading. The pattern of variation of field direction and intensity is recorded in volcanic or stratigraphic sequences and provides the basis of magnetostratigraphy. More localized anomalies provide information about the subsurface structure and composition of the Earth’s crust and are an important index for the presence of certain metallic (generally ferruginous) ore deposits.

See Also


Magnetic Field Oceanic Crust Magnetic Anomaly Field Direction Negative Polarity 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Maison des GéosciencesLGCA, Université J. FourierSt-Martin d’HèresFrance