This research used samples and/or data supplied by the Ocean Drilling Program (ODP). ODP is sponsored by the U.S. National Science Foundation and participating countries under management of Joint Oceanographic Institutions (JOI), Inc. This research was funded by the Petroleum Research Fund (grant number 40226) and a grant from JOI U.S. Science Support Program (USSSP). Finally, we would like to thank Barbara Bekins, Jay Miller, and two anonymous reviewers for their comments, which greatly improved the quality of this paper.