We are indebted to ODP for providing samples for this study. We would also like to specially thank David Bukry for his precious help and Raffaella Ruffini for useful discussion on the volcanic input. The reviews of the referees Isabella Raffi and Francine McCarthy are warmly acknowledged. This research used samples provided by the Ocean Drilling Program (ODP). The 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 CNR (Consiglio Nazionale delle Ricerche, Italy) and MIUR (Ministero dell'Istruzione, Università e Ricerca, Italy).