We thank R. von Grafenstein for stimulating discussions. A special thank-you is addressed to E. de Kaenel for the long and constructive exchanges to obtain a unique coherent chronology based on the nannofossil and oxygen isotope time scales. We are also greatly indebted to the two reviewers who have largely contributed to improve the initial manuscript. Thanks are due to L. Vigliotti for supplemental samples from Hole 975C. Isotopic analyses completed in the U.S. were supported by the USAAC/JOI funding. The isotopic analyses completed in France received the financial support of the Institut National des Sciences de l'Univers of CNRS (INSU grant no. 96 "Géosciences Marines").