Résumé
The MoHole Project, drilling into an intact portion of oceanic lithosphere through the crust to the Moho discontinuity and the uppermost mantle, is a long-standing goal of scientific ocean drilling. Three candidates of the MoHole drilling are decided on thoroughly taking into account the scientific objectives, feasible technology developments and the operation condition of the drill ship during two international workshops held in 2010. A drilling expedition into the oceanic lower crust was carried out during IODP Expedition 335 -Superfast Spreading Rate Crust 4- at one of the three site candidates, ODP Site 1256 (Hole 1256D). It was the fourth scientific drilling cruise, following ODP Leg 206, IODP Exp. 309 and Exp. 312, of the Superfast Spreading Crust campaign to ODP Hole 1256D. The MoHole project remains critical to answer many fundamental questions about the dynamics of the Earth and global elemental cycles.