This research used samples and/or 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 in part by Research Fellowships from the Japan Society for the Promotion Science for Young Scientists (grant no. 0104014) and by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology (grant no. 11691113).
We are truly grateful to Gary Acton, Lorri Peters, and Bryan C. Ladner for their critical reviews and constructive opinions. We wish to express thanks to T. Sakamoto (Hokkaido University) and Y. Tanaka (National Institute of Advanced Industrial Science and Technology) for their helpful suggestions.