ACQUISITION OF NATURAL REMANENT MAGNETIZATION IN SNOW AND ICE CONTAINING ROCK DUST

概要

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Paleomagnetic study of the dirt-ice collected at the Allan Hills in Antarctica showed stable remanent magnetization in the dirt-ice (FUNAKI and NAGATA, Mem. Natl Inst. Polar Res., Spec. Issue, 39,209,1985). However, the magnetization mechanism has not been investigated at all. We performed the experiments to make clear the magnetization mechanisms of the dirt-snow and dirt-ice. Two types of artificial samples were prepared for this purpose. One was the dirt-ice frozen from the wet-snow and the other was the dry-snow containing rock dust. The former samples acquired the stable remanent magnetization parallel to the geomagnetic field. This natural remanent magnetization (NRM) was acquired immediately during the freezing process from the wet-snow. The latter samples preserved under the low temperature conditions of both -10 and -20℃, acquired gradually the NRM in the direction of the geomagnetic field. The NRM's moment in the latter samples was not saturated during the 22-day preservation in the low temperature conditions. The acquisition of NRM advanced more effectively under the temperature of -10 than -20℃. The experimental data obtained indicate that the NRM of the dirt-ice and dirt-snow may become a useful means for paleomanetic and glaciological studies.
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