Behavior of oceanic crustal magnetization at high temperatures: Viscous magnetization and the marine magnetic anomaly source layer

Authors

Julie A. Bowles, University of Wisconsin-MilwaukeeFollow
H. Paul Johnson, University of Washington - Seattle Campus

Document Type

Article

Publication Date

8-1-1999

Abstract

Although the source layer for marine magnetic anomalies has been assumed to be the extrusive basalts of uppermost ocean crust, recent studies indicate that lower crustal rocks may also contribute. Because the temperature at which magnetization of crustal rocks achieves long-term stability is crucial to any source layer contribution, we undertook high-temperature VRM (viscous remanent magnetization) experiments on samples of basalt, dike and gabbroic sections. Samples were heated at temperature intervals up to T_c, while a magnetic field was applied for periods between 6 hours and 28 days. Results show that the dike and gabbro samples achieve maximum VRM acquisition near 250°C, well below the T_c of 580°C. The basalt sample shows a peak at 68°C, also well below T_c. Results of this pilot study indicate that the critical isotherm for stable magnetization acquisition is defined by the VRM behavior of the specific crustal section.

Comments

Originally published in Geophysical Research Letters, v.26, no.15 (August 1, 1999)

Recommended Citation

Bowles, Julie A. and Johnson, H. Paul, "Behavior of oceanic crustal magnetization at high temperatures: Viscous magnetization and the marine magnetic anomaly source layer" (1999). Geosciences Faculty Articles. 8.
https://dc.uwm.edu/geosci_facart/8