This work benefited from many helpful discussions with Lisa Tauxe, Jeff Gee, and Thomas Westerhold. Stefanie Brachfeld provided a very constructive review that helped improve the manuscript. The author would also like to thank the scientists, staff, and crew of Leg 208. Special thanks go to Lauren Kay for assistance with many measurements. 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 the U.S. Science Support Program.