Site U1312

Site U1312 (proposed Site IRD4A) constitutes a reoccupation of Deep Sea Drilling Project (DSDP) Site 608 located northeast of the Azores on the southern flank of the King's Trough tectonic complex in a water depth of 3554 m. During DSDP Leg 94, two principal holes (Hole 608 and Hole 608A) were drilled (Ruddiman, Kidd, Thomas, et al., 1987). Hole 608 was continuously cored with the variable-length hydraulic piston coring (VLHPC) system and the extended core barrel system down to the basement at 515.4 meters below seafloor (mbsf) (42 Ma), and Hole 608A was continuously cored with the VLHPC to refusal at 146.4 mbsf (3.4 Ma). At this site, a nearly continuous bio- and magnetostratigraphic section of Quaternary to middle upper Oligocene sediments was recovered to 455 mbsf (Baldauf et al., 1987). Below this depth, some coring gaps and the presence of a major hiatus representing at least 7.5 m.y. (late Eocene-early Oligocene) cause the record to be less complete through the Oligocene and into the Eocene. Upper middle Eocene (Zone NP16) sediments lie upon the basaltic basement at 515.4 mbsf. Mean sedimentation rates at Site 608 are 2-3 cm/k.y., with the higher values generally occurring in the late Neogene-Quaternary time intervals.