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doi:10.2204/iodp.proc.323.107.2011

Operations

Five holes were cored at Site U1343 (Table T1). Hole U1343A was cored with the advanced piston corer (APC) system and drilled to 201.5 m drilling depth below seafloor (DSF). Hole U1343B was dedicated to microbiology and cored to 35.5 m DSF. Hole U1343C was cored with the APC system to 234.2 m DSF. Only a single mudline core was taken in Hole U1343D, and we decided to attempt another mudline core for stratigraphic correlation. Hole U1343E was cored with the APC and extended core barrel (XCB) systems to 744.3 m DSF. The XCB system was needed for Cores 323-U1343E-42X through 45X, where we encountered dry sediment and retrieved a destroyed core liner (42X), and for the deepest cores (323-U1343-50X through 83X). The shallower interval cored with the XCB system coincided with a bottom-simulating reflector (BSR). Coring was generally routine except for encountering biogenic methane in the cores, which complicated the curation of all cores at this site. APC coring totals for Site U1343 include 98 cores, 860.4 m penetrated, and 860.0 m recovered, for 100% core recovery. XCB coring for Site U1343 totaled 37 cores, 360.6 m penetrated, and 318.41 m recovered, for 88.3% core recovery. The total cored interval for Site U1343 was 1221.0 m with 1178.43 m of core recovered, for 96.5% total core recovery. The time spent at Site U1343 was 6.7 days.

Hole U1343A

Hole U1343A was spudded at 0305 h on 7 August 2009 (all times are ship local time, Universal Time Coordinated [UTC] – 11 h). The first mudline core recovered 5.5 m of sediment, and the calculated seafloor was 1962.4 m drilling depth below rig floor (DRF). APC coring using nonmagnetic coring assemblies continued through Core 323-U1343A-22H to 201.5 m DSF. Temperature measurements were taken on Cores 323-U1343A-5H, 9H, and 14H with the third-generation advanced piston corer temperature tool (APCT-3). Core orientation was taken on all cores with the FlexIt orientation tool, but the data were lost when the computer running the download software was accidentally switched off during the FlexIt operations, causing the program to lose synchronization with the tool. Overall core recovery for Hole U1343A using the APC system was 101.26%, with 204.03 m recovered.

Hole U1343B

The vessel was offset 30 m north, and Hole U1343B was spudded at 2240 h on 7 August. The first mudline core recovered 6.85 m of sediment, and the calculated seafloor was 1962.4 m DRF. Both perfluorocarbon tracer (PFT) and microsphere contamination testing methods were deployed. Four APC cores were recovered for microbiological sampling to 35.5 m DSF. Average APC core recovery for Hole U1343B was 97.4%, with 34.56 m recovered.

Hole U1343C

The ship was offset 30 m west from the proposed site position. The APC was deployed, and Hole U1343C was spudded at 0305 h on 8 August. The first mudline core recovered 7.2 m of sediment, and the calculated seafloor was 1964.2 m DRF. APC coring using nonmagnetic coring assemblies continued through Core 323-U1343C-26H to 234.2 m DSF. Overall core recovery for Hole U1343C using the APC coring system was 98.7%, with 231.04 m recovered.

Hole U1343D

Hole U1343D was spudded 30 m south of Hole U1343C at 0135 h on 9 August. Based on stratigraphic correlation of the first and only core, Hole U1343D was terminated at 0135 h. Overall core recovery for Hole U1343D using the APC coring system was 100.0%, with 8.5 m recovered.

Hole U1343E

Hole U1343E was not offset from Hole U1343D and was spudded at 0215 h on 9 August. The first core barrel recovered 8.2 m of core, and an official seafloor depth was established at 1967.5 m DRF. APC coring continued through Core 323-U1343E-15H using standard steel core barrels. At Core 323-U1343E-16H the nonmagnetic barrels were put in service and used for the rest of the hole. Coring with the APC system was suspended after Core 323-U1343E-41H was pulled with a ruptured core liner and had to be hydraulically pressed out of the core barrel. This coincided with a BSR observed in the seismic data. The core was also noticeably drier and harder at this depth. The XCB coring system was then deployed from Cores 323-U1343E-42X through 45X with good recovery. The APC coring system was put back into service for Cores 323-U1343E-46H through 49H. At that time we began to get partial strokes of the piston and were having to drillover every core. The XCB system was redeployed, and coring continued through Core 323-U1343E-83X to 744.3 m DSF. The coring tools were secured, and the hole was swept clean and displaced with 200 bbl of prepared high-viscosity logging mud. No fill was identified at total depth. Two logging strings were deployed. The triple combination (triple combo) tool string reached total depth of 745 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, which reached total depth of 745 m WSF and also obtained good data on both passes. Wireline logging in Hole U1343E was successfully concluded and all logging equipment was rigged down by 0745 h on 13 August. APC core recovery for Hole U1343E was 100.3%, with 381.86 m recovered. XCB core recovery for Hole U1343E was 88.3%, with 318.41 m recovered. Total core recovery for Hole U1343E was 94.47%, with 700.27 m recovered.

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