We thank John Barron, Jack Baldauf, Gary Acton, Lorri Peters, and Itaru Koizumi for their critical reviews and suggestions for improving the manuscript. Thanks are also extended to Isao Motoyama, Nobuaki Niitsuma, Saneatsu Saito, and crew members of Leg 186 of the JOIDES Resolution for their support and encouragement. This 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. The authors are deeply indebted to Kiyoshi Suyehiro, Tatsuhiko Sakamoto, and Mimi Bowman for their considerable assistance with sample circulation in the 4 months before the postcruise meeting was held in September 2001 in Kanazawa, Japan.