Figure F3. A. Spectra of Mn K-edge XANES for the reference materials made by mixing Mn(II)SO₄ and -Mn(IV)O₂. Total concentration of Mn was 2000 ppm adjusted by diluting with quartz sand. The molar ratio of Mn(II) and Mn(IV) is indicated in the figure. B. The relationship between the average valence of Mn and the energy shift of the pre-edge peak in the reference material from the pre-edge of -MnO₂. C. An example of fitting results of the pre-edge of Mn K-edge XANES for sediment samples from 0.60 and 1.82 mbsf recovered from Hole 1179B cores. It is clearly observed that Mn at 1.82 mbsf is more reduced than that at 0.60 mbsf.