The authors would like to thank Ben Swanson, Andrea Mullen, and Chip Heil for helping with laboratory work. Paul Johnson provided assistance with TEM imaging, and many thanks to Steve D'Hondt and other Leg 201 scientists for thoughtful conversations. This manuscript was improved by the helpful revisions of Robert Musgrave. 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 by U.S. Science Advisory Committee (USSAC).