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doi:10.2204/iodp.proc.303306.113.2006

Operations

We arrived at Site U1314 (proposed Site GAR1B) early Thursday morning, 7 April 2005, after a 943 nmi transit from Site U1313. Positioning beacon SN 2199 (15.0 kHz, 211 dB) was deployed at 0330 h, and operations at Site U1314 officially began. See Table T1 for the coring summary.

Hole U1314A

Hole U1314A was spudded at 0950 h on 7 April 2005. Core 1H recovered 1.95 m of sediment and established a rig floor–corrected seafloor depth of 2810.6 meters below rig floor (mbrf). Coring continued with the advanced piston corer (APC) without incident in Hole U1314A until Core 28H at a depth of 258.4 meters below seafloor (mbsf). The overshot pin sheared during the attempt to recover Core 28H. Unfortunately, the driller did not initially realize that the core barrel was not being recovered and proceeded to drill downhole in preparation for the next core. After recovering the core barrel on the second wireline run, the APC system was found to be heavily damaged, including overtorqued piston rod connections and other damage. Because it was going to take an hour or more to repair and rebuild the APC system, the Co-Chief Scientists elected to terminate coring in Hole U1314A and proceed with the next hole. After repairing the APC, the drill string was pulled clear of the seafloor at 1100 h on 8 April, officially ending operations in Hole U1314A.

Tensor core orientation was used for all cores beginning with Core 4H from a depth of 20.9 mbsf. Drillover of stuck APC barrels was not required, and all core barrels fully stroked. Nonmagnetic core barrels were used to recover all 28 cores. Problems with swollen or imploded core liners were more prevalent in this hole than experienced previously at the other sites. Of 28 cores recovered, four liners suffered some swelling (Cores 12H, 15H, 16H, and 23H) and six core liners either shattered (Core 20H) or imploded (Cores 18H, 22H, 26H, 27H, and 28H). In addition, four barrels mechanically sheared during deployment (Cores 2H, 4H, 6H, and 11H). These problems were most likely heave induced and led to more disturbed and lower-quality core than normally experienced with the APC system. The cored interval for this hole was 258.4 m, and 267.34 m of sediment was recovered (103.5%).

Hole U1314B

The drillship was offset 25 m due north (000°) of Hole U1314A. The bit was positioned at a depth of 2806.0 mbrf, or 3.0 m deeper than Hole U1313A, to offset the core breaks between cores. Hole U1314B was spudded at 1220 h on 8 April 2005, and Core 1H recovered 4.02 m and established a rig floor–corrected seafloor depth of 2811.5 mbrf. APC coring with nonmagnetic core barrels continued without incident in Hole U1314B through Core 30H to a total depth of 279.5 mbsf. Tensor core orientation was used for all cores beginning with Core 4H from a depth of 23.0 mbsf. All core barrels fully stroked, and no drillover was required in this hole. The cored interval for this hole was 279.5 m, and 285.36 m of sediment was recovered (102.1%). The drill string was pulled clear of the seafloor at 1155 h on 9 April, officially ending operations in Hole U1314B. Although there still were some core liner incidents in this hole, core quality was improved. Of the 30 cores recovered, four liners were recovered swollen (Cores 15H, 21H, 22H, and 26H) and another three were imploded at the bottom end (Cores 9H, 19H, and 27H). The overshot pin sheared once on Core 6H, requiring a second wireline run to recover the core barrel.

Hole U1314C

The drillship was offset 25 m due east (90°) of Hole U1314B. The bit was positioned at a depth of 2809.0 mbrf, or 6.0 m deeper than Hole U1314A, again to offset the core breaks. Hole U1314C was spudded at 1320 h on 9 April 2005, and Core 1H recovered 8.22 m and established a rig floor–corrected seafloor depth of 2810.3 mbrf. APC coring with nonmagnetic core barrels continued in Hole U1314C through Core 22H to a total depth of 207.7 mbsf. During this period, the weather deteriorated as a major gale approached our location and brought high winds and steadily building seas and swells with it. By Sunday morning, we had long-period heave cycles in excess of 5 m and storm-force winds were forecast for the Site U1314 location by late Sunday or early Monday. Tensor core orientation was used for all cores beginning with Core 3H from a depth of 17.7 mbsf. All core barrels fully stroked, and no drillover was required in this hole. The cored interval for this hole was 207.7 m, and 212.93 m of sediment was recovered (102.5%). The drill string was pulled clear of the seafloor at 0915 h on 10 April, and positioning beacon SN 2199 was recovered during the pipe trip, officially ending operations at Site U1314 at 1030 h. After we recovered and stored the drill string, the ship was secured for transit and all thrusters and hydrophones were pulled. At 1545 h on 10 April, the ship was switched from dynamic positioning to cruise mode and began the sea voyage to Site U1315 (Site 642 on the Vøring Plateau).

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