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. Funding for this research was provided by a grant from the U.S. Science Support Program. We thank Brann Johnson for the use of his laboratory facilities. We also thank the captain and crew of the JOIDES Resolution. We are particularly indebted to ODP and ODP technicians Anastasia Ledwon and Jessica Huckemeyer.