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. A research assistantship for N. Hoffman was provided by JOI and U.S. Science Support Program (USSSP) postcruise funding for ODP Leg 190. The authors wish to thank J.C. Moore for helpful suggestions and Lorri Peters for editorial review.