Deep Drill 1972: a paleomagnetic study of the Bermuda Seamount

Abstract

The rock and paleomagnetic character of an 802 m core drilled on the Bermuda Seamount is described. Intrusion of highly evolved, limburgitic Tertiary sheets, which comprise 40% of the core, into older tholeiitic submarine lavas has produced extensive stable additional magnetization in the flows. Original and later components of the supposed polyphase magnetization of the flows have not yet been separated by the alternating field or thermal methods of remanence analyses. It is thought that both remanence components are held in nearly pure magnetite with similar grain size distributions.Development of additional magnetization in the high temperature hydrothermal conditions experienced by the flows is volumetrically much more extensive than baked thermal remagnetization, and could, in appropriate circumstances, provide a uniformly magnetized, lower layer 2 source for the linear magnetic anomaly patterns of the ocean basins.