We are grateful to the Leg 164 shipboard scientific parties who shared sampling duties and the helpful technical staff of the ODP during Leg 164. We are grateful to Professors W. Ussler and R.W. Murray for critical reading of the manuscript. We also thank Dr. N. Imai of GSJ for support on analytical facilities. This study is partly supported by the AIST Special Research Fund from the Ministry of International Trade and Industry of Japan, which was provided to Y. W.