We are indebted to J. Girardeau, C. Lecuyer, D. Teagle, A. Klaus, B. Whitmarsh, and D. Sawyer for useful comments and suggestions. The first author would like to thank Adam Klaus and Stuart R. Boyd for editing the English of this manuscript. We thank Sandra Panzolini, Agnes Michel, Michel Girard, and Jean-Jacques Bourrand for their help. This study was supported by INSU Geosciences Marines Funds.