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The IODP Expedition 309/312 shipboard scientists dedicate this volume to the Transocean operations and rig floor team of the JOIDES Resolution.

Hole 1256D penetrates >1250 m into previously “undrillable” Pacific basement and remains clear of debris, ready for deepening on future expeditions. This is a major engineering accomplishment and a milestone in scientific ocean drilling. Hole 1256D is now the fourth deepest hole drilled into oceanic basement and the second deepest penetration into intact ocean crust, shallower only than Deep Sea Drilling Project/​Ocean Drilling Program Hole 504B. Importantly, Hole 1256D provides the first complete section of the upper oceanic crust from the erupted lavas, through the sheeted dikes, and into gabbros. Such a section has been one of the major desires of marine geologists and geophysicists since the inception of scientific ocean drilling in 1968.