Multiple Reversals of Natural Remanent Magnetization in a Granite-Aplite Dyke of the Bergell Massif (Switzerland)

Abstract

Stable remanent magnetization of a granite-aplite dyke forms stripes of normal and reversed polarity. Phenomenological evidence suggests that the different polarities are caused by self-reversal of ilmenohematite, the carrier of stable remanence. Thermal experiments show an ‘imperfect’ self-reversal which is based on the presence of two interacting phases with different Curie points within the exsolved ilmenohematite. Perfect self-reversal of natural remanent magnetization may have occurred during the original slow cooling of the granite-aplite dykes which, below the blocking temperature, obviously have the same cooling history as the main Bergell granite massif. © 1974, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved.