During operations at Site 1146, the vessel received approval for coring Site 1147 (newly proposed site SCS-5F) to a depth of 100 mbsf. This site was less than one mile west of Site 1148 (proposed site SCS-5C). The plan was to piston core three holes to a depth of ~80 mbsf to recover the upper part of the Pleistocene section that, judging from seismic records, appeared to be missing at Site 1148. The 40-nmi transit to Site 1147 took 4 hr at an average speed of 9.5 kt. The beacon was dropped on Global Positioning System coordinates at 1035 hr on 29 March. The corrected precision depth recorder referenced to the dual elevator stool was 3256.4 m.
Hole 1147A was spudded with the advanced hydraulic piston corer (APC) at 1815 hr on 29 March. The seafloor depth was inferred at 3257.5 m from the recovery of the first core. Piston coring advanced with nine APC cores to 81.4 mbsf with an average recovery of 100.4% (Tables T1, T2, both also in ASCII format). Cores were oriented starting with Core 3H.
The vessel was moved in dynamic positioning mode 10 m east of Hole 1147A. Hole 1147B was spudded with the APC at 0245 hr on 30 March. The inferred seafloor depth was 3257.0 m. Piston coring advanced with nine APC cores to 85.5 mbsf with an average recovery of 100.0% (Tables T1, T2). Cores were oriented starting with Core 3H.
The ship was moved 10 m east of Hole 1147B. Hole 1147C was spudded with the APC at 1045 hr on 30 March. The inferred seafloor depth was 3256.9 m. Piston coring advanced with nine APC cores to 78.6 mbsf with an average recovery of 97.5% (Tables T1, T2). Cores were oriented starting with Core 2H.
The total recovery for this site was 243.8 m, or 99.3% of the cored interval of 245.5 m. After the bit was pulled clear of the seafloor at 1820 hr on 30 March, it was raised ~50 m above the seafloor in preparation for the move to Site 1148. After the beacon was released and recovered at 1915 hr, the JOIDES Resolution was moved to Site 1148, ~0.5 nmi east of Site 1147, in dynamic positioning mode.