Viscous remanent magnetization of basalts from the Bouvet triple junction,South Atlantic

The magnetic viscosity of oceanic basalts dredged from the Atlantic Ocean f loor in the Bouvet triple junction region is studied. The magnetic viscosit y is shown to have a preferably diffusion origin and is controlled by the p roperties of titanomagnetite grains. The value and stability of the viscous remanent magnetization (VRM) are highest if the titanomagnetite grains hav e pseudosingle-domain sizes and are at a certain stage of single-phase oxid ation. Some basalt samples are characterized by anomalous behavior of VRM c urves as a function of the field and time.