The research used samples and data provided by the Ocean Drilling Program (ODP). ODP is sponsored by the U.S. National Science Foundation (NSF) and participating countries under management of Joint Oceanographic Institutions (JOI), Inc. Funding for this research was provided by the Russian Foundation for Fundamental Research (numbers 98-05-64856 and 99-05-65462).
We thank the reviewers for useful critical remarks. We also would like to thank S.M. Liapunov (XRF and neutron-activation analysis), I.Y. Lubchenko (atomic emission spectroscopy), and N. Kalashnikova and G. Granovsky (wet chemical analysis).