Open AccessMagnetic dipole anomalies as indicators of mantle wedge serpentinization
Author(s) -
Kido Yukari,
Kido Motoyuki,
Fujioka Kantaro
Publication year - 2004
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2004gc000697
Subject(s) - geology , forearc , magnetic anomaly , geophysics , diapir , paleomagnetism , earth's magnetic field , mantle (geology) , accretionary wedge , remanence , magnetization , tectonics , seismology , subduction , magnetic field , physics , quantum mechanics
Fine‐scale magnetic anomaly data based on high‐density airborne surveys have revealed several dipole anomalies along the Chichibu Zone (CZ), which lies parallel to the Nankai Trough and forms a part of the accretionary complex of southwest Japan. A plausible explanation of magnetic sources for the anomalies is a series of fossil serpentine diapirs involved during the accretion process. Serpentine diapirs are known to be developed in several forearc regions as mantle wedge serpentinized material associated with dehydration of the subducting oceanic slab. Surface geological and paleomagnetic evidence also suggests the existence of serpentine bodies in the CZ. We applied a magnetic inversion to each of the dipole anomalies and determined the magnetic bodies in a triaxial ellipsoid approximation. Magnetic bodies are interpreted to lie nearly parallel to the CZ and are inclined southward. Intensities of magnetization are compatible with those expected by measured susceptibilities of samples in the subareal CZ, and their directions are roughly the same as the current geomagnetic field, implying that the induced magnetization is dominant rather than the remanent component.