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Ilmenite lamellae and stability of magnetization
Author(s) -
BeskeDiehl S. J.
Publication year - 1988
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl015i005p00483
Subject(s) - ilmenite , remanence , magnetite , magnetization , natural remanent magnetization , coercivity , subaerial , geology , demagnetizing field , mineralogy , basalt , materials science , single domain , pseudomorph , geochemistry , magnetic domain , magnetic field , condensed matter physics , quartz , paleontology , physics , quantum mechanics
I have analyzed magnetic data from four deep‐sea basalts which have undergone the “exsolution” stage of high‐temperature oxidation, but have not begun the “replacement” stage. Even when ilmenite lamellae development was extensive, coercivities were low with a coercive force (H c ) of 11.7 mT (1 mT=10 Oe) and medium destructive field (MDF) of 9.1 mT. The remanence vector exhibited a directional swing of 30° upon alternating field (AF) demagnetization. Thus, few of the titanomagnetite intergrowths behaved like single‐domain grains. This tentative conclusion is supported by those previous studies of subaerial basalts and synthetic materials which optically identified the degree of oxidation and in which no titanomagnetite granulation was observed. In these studies, MDF's generally did not increase above 15 mT during ilmenite lamellae formation. Those natural and synthetic samples which exhibit features of the “replacement” stage have large natural remanent magnetization (NRM) intensities and high coercivities suggesting that despite intense hematization, single‐domain magnetite may still be present.