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doi:10.2204/iodp.proc.323.105.2011

Operations

A positioning beacon was deployed at Site U1341 at 2311 h on 26 July 2009 (all times are ship local time, Universal Time Coordinated [UTC] – 11 h). Three holes were drilled at this site (Table T1). A complete set of site-specific tide tables was provided by the science party for Site U1341 and used to make adjustments relative to initial mudline core and for each successive core in each hole. A new continuous advanced piston corer (APC) coring depth record was established when Hole U1341B reached 458.4 m drilling depth below seafloor (DSF). Coring for Site U1341 totaled 139 cores, 1189.2 m penetrated, and 1210.3 m recovered, for 102% core recovery (Table T1). The time spent at Site U1341 was 170.5 h (7.1 days).

Hole U1341A

Hole U1341A was spudded at 0510 h on 27 July. The first APC barrel recovered 3.04 m of core, and an official seafloor depth was established at 2150.9 m drilling depth below rig floor (DRF). APC coring using nonmagnetic coring assemblies with the FlexIt orientation tool installed continued through Core 323-U1341A-20H to 2334.4 m DRF. At this point, the nonmagnetic coring equipment was changed to the standard APC coring system and coring continued. Coring with the APC system was suspended after Core 323-U1341A-41H after two successive short, incomplete strokes of the core barrel. Overall core recovery for Hole U1341A using the APC coring system was 104%, with 373.2 m recovered (Table T1).

Hole U1341B

The vessel was offset 20 m east of Hole U1341A, and Hole U1341B was spudded at 2245 h on 28 July. The first APC barrel recovered 8.7 m of core, and an official seafloor depth was established at 2150.9 m DRF. APC coring using nonmagnetic coring assemblies with the FlexIt orientation tool installed continued through Core 323-U1341B-18H to 166.7 m DSF. Coring with the APC system was suspended after Core 323-U1341B-56H after three successive short, incomplete strokes of the core barrel. A new continuous APC coring record was established with continuous piston cores from the mudline to 458.4 m DSF. The extended core barrel (XCB) coring system was then deployed for Cores 323-U1341B-57X through 71X. The hole was terminated after Core 323-U1341B-71X when the total depth of the hole reached 600.0 m DSF. APC core recovery for Hole U1341B was 102%, with 467.64 m recovered. XCB core recovery for Hole U1341B was 88.2%, with 126.9 m recovered. Total core recovery was 98.7%, with 595.0 m recovered (Table T1). After coring, the coring tools were secured, and the hole was swept clean and displaced with 200 bbl of high-viscosity logging mud. No fill was identified at total depth. The top drive was set back, and the drill pipe was tripped to 80 m DSF while the hole was monitored for problems. The end of pipe was placed at ~80.0 m DSF. Rig-up for wireline logging began at 1930 h on 31 July. Two logging strings were deployed. The triple combination (triple combo) tool string reached the total hole depth of 600 m wireline log depth below seafloor (WSF), and good-quality logs were obtained. The second logging string consisted of the Formation MicroScanner (FMS)-sonic tool. This tool string also reached the total depth of 600 m WSF and also obtained good data on both passes. Wireline logging in Hole U1341B was successfully concluded and all logging equipment was rigged down by 1530 h on 1 August.

Hole U1341C

Operations in Hole U1341C commenced at 1555 h on 1 August. The vessel was moved 20 m east of Hole U1341B, and Hole U1341C was spudded at 1810 h. The first APC barrel recovered 5.5 m of core, and an official seafloor depth was established at 2150.9 m DRF. APC coring using nonmagnetic coring assemblies with the FlexIt orientation tool installed continued through Core 323-U1341C-17H to 147 m DSF. At this point, standard steel core barrels were installed, and coring continued through Core 323-U1341C-27H to 230 m DSF. Overall APC core recovery was 242.06 m (106.2%) (Table T1).

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