Previous   |    Next

doi:10.2204/iodp.proc.329.107.2011

Operations

Transit to Site U1369

After a 98.1 h transit from Site U1368, covering 1073 nmi and averaging 10.9 kt, speed was reduced and thrusters were lowered. Dynamic positioning was initiated over Site U1369 at 1454 h on 22 November 2010. The position reference was a combination of GPS signals. No acoustic beacon was deployed, but a beacon remained on standby in the event of a loss of GPS satellite coverage. Whereas automatic input into the dynamic positioning system was not possible because of a system malfunction, it was possible to manually hold the vessel in position to clear the seafloor with the bottom-hole assembly if necessary.

All times in this section are given in local ship time unless otherwise noted. For most of the expedition, local time was Universal Time Coordinated – 10 h.

Site U1369

Five holes were drilled or cored at Site U1369 (Table T1). The first hole was a washdown hole drilled with the center bit in order to establish the sediment depth of 12.2 mbsf. The next four holes were cored with the advanced piston corer (APC) system. The advanced piston corer temperature tool was not deployed because of the shallow sediment depth. Perfluorocarbon tracer (PFT) was pumped for the entire drilling/coring interval until the last core was on deck. APC system recovery for Site U1369 was 108%. A total of 10 cores were attempted while coring 46.1 m. The total length of core recovered at this site was 49.81 m (108.0% recovery).

Hole U1369A

Rig floor operations commenced at 1445 h on 22 November 2010. The trip to the seafloor was uneventful. The top drive was picked up and the drill string was spaced out and spudded at 0040 h on 23 November. The PFT pump was turned on to displace the drill string with the contamination testing fluid. The washdown hole was drilled to determine depth of basement. Mudline was established at 5290.5 meters below rig floor (mbrf) by tagging with the bit. After drilling down, basement was established at 12.2 mbsf. The bit was pulled back above the seafloor, clearing the seafloor at 0125 h and ending Hole U1369A.

Hole U1369B

After clearing the seafloor, the center bit was pulled by wireline, the vessel was offset 20 m west, and the drill string was spaced out to spud Hole U1369B. After making up the first APC core barrel, the core barrel was run to bottom on the wireline and Hole U1369B was spudded at 0350 h on 23 November. Seafloor depth was established at 5286.3 mbrf with a mudline core. APC coring continued to 15.9 mbsf. An extended core barrel was dropped after an initial analysis from the science party based on concern that the deepest material recovered might not have been igneous in origin. Subsequent analysis verified the rock samples to be igneous in origin and the core barrel was pulled without advancing. Three cores were taken with a total recovery of 18.14 m (114.1%). After Core 329-U1369B-3H, the bit was tripped back to just above the seafloor, ending Hole U1369B at 1030 h. PFT was mixed with the drilling fluid (seawater) and pumped on all cores for contamination testing.

Hole U1369C

Hole U1369C began at 1030 h when the APC assembly cleared the seafloor after completing Hole U1369B. After offsetting the vessel 20 m north, Hole U1369C was spudded at 1135 h and advanced with the APC system to 14.6 mbsf before encountering basement. Seafloor was established at 5288.0 mbrf. PFT was mixed with the drilling fluid (seawater) and pumped on all cores for contamination testing. Three cores were taken with a total recovery of 16.1 m (110.3%). The drill string was tripped to just above the mudline, clearing the seafloor at 1530 h on 23 November and ending Hole U1369C.

Hole U1369D

Hole U1369D began at 1530 h when the APC assembly cleared the seafloor after completing Hole U1369C. After offsetting the vessel 20 m east, Hole U1369D was spudded at 1615 h on 23 November. The core liner was shattered and even though the core barrel extended 9.5 m, manganese nodules in the core catcher comprised the only material recovered. Hole U1369D was abandoned. Seafloor was established at 5288.0 mbrf using an offset from the previous hole. Recovery was limited to a 0.08 m core length, and the advance was recorded as 0.1 m. Percentage of recovery is recorded as 80%. PFT was mixed with the drilling fluid (seawater) and pumped on all cores for contamination testing. The hole ended at 1615 h with the mudline shot.

Hole U1369E

Hole U1369E began at 1615 h on 23 November after the failed mudline core on Hole U1369D. The vessel was offset 20 m east of Hole U1369D. After making up the first APC core barrel, the core barrel was run to bottom on the wireline and Hole U1369E was spudded at 1745 h. Seafloor depth was established with a mudline core at 5288.8 mbrf. The APC system was used to take three cores to 15.5 mbsf with a 15.49 m recovery (99.9%). PFT was mixed with the drilling fluid (seawater) and pumped on all cores for contamination testing. The drill string was tripped to the surface, clearing the rotary table at 0645 h on 24 November. The rig floor and secured for the 625 nmi transit to the next site, ending Hole U1369F and Site U1369 at 0730 h on 24 November.

Top of page   |    Previous   |    Next