Low-temperature demagnetization of volcanic rocks containing multi-domain magnetic grains: Implications for the Thellier paleointensity determination

Abstract

Thirteen samples of volcanic rocks from Caucasus, Iceland and Philippines were subjected to low-temperature treatment in order to remove the part of remanent magnetization carried by multi-domain grains. Ten to 40% of multi-domain partial thermoremanence were removed, which may help to increase the success of paleointensity experiments. A sample from the 1991 eruption of Pinatubo volcano shows a total self-reversal due to ilmeno-hematites and partial self-reversal between 500° and 575 °C due to titano-magnetites. Low temperature demagnetization applied to self-reversed remanence suggest that the high-temperature peak is almost suppressed by this treatment.

Keywords

• Rock-magnetism
• low-temperature demagnetization
• domain structure