Paleomagnetic study of Pleistocene lavas and dikes of the Zao Volcano Group, Japan

Abstract

All the rock units collected have radiometric ages obtained by K-Ar method which cover the last one million years. Among 16 paleodirections obtained eleven belong to the Brunhes chron, four to the Matuyama chron and one probably to the Jaramillo subchron. Paleointensity experiment by the Thelliers' method was applied to a total of 70 specimens from nine cooling units. Among them, 31 specimens gave successful results and four and two paleointensities were obtained for the Brunhes and Matuyama chrons, respectively. Some correlations were found between the success rate of paleointensity experiment and reproducibility of the continuous measurements of magnetic susceptibility versus temperature. -from Authors