Fig. 6

Orthogonal vector diagrams for representative results of the hybrid demagnetization method. a, b Results indicating normal polarity from the upper part of the Yoro River section (this study). c, d Results indicating intermediate polarity in the interval of instability clusters (IC1–IC3) from the Yoro-Tabuchi section (c Simon et al. 2019; d Okada et al. 2017). e–g Specimen data across the M–B boundary in the lowermost part of the Yoro-Tabuchi section (this study). h, i Results from the Matuyama reversed polarity interval from the Chiba section (Okada et al. 2017). Closed and open circles indicate horizontal and vertical components, respectively. Closed and open black data points were used to calculate characteristic remanent magnetization in the principal component analysis