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doi:10.2204/iodp.proc.323.103.2011

Operations

We arrived at Site U1339 early on 16 July 2009 after a 6.5 day, 1782 nmi transit from Victoria, British Columbia, Canada, and operations officially began. The coring summary for this site is provided in Table T1.

One relatively shallow and three relatively deep holes were drilled and cored using the advanced piston corer (APC) at a water depth of 1867 m on Umnak Plateau: Hole U1339A (33.4 m drilling depth below seafloor [DSF]), Hole U1339B (196.0 m DSF), Hole U1339C (194.8 m DSF), and Hole U1339D (200.0 m DSF). Cores 323-U1339B-1H through 4H were primarily used for subseafloor microbial study, and both perfluorocarbon tracer (PFT) and whirlpack bags containing fluorescent microbeads were deployed. The remaining cores were used for paleoceanographic studies. Most cores had nearly 100% or greater recovery because of gas expansion. The exceptions are two short cores (323-U1339B-13H [2 m] and 323-U1339C-16H [4.5 m]) that were recovered when the APC fired into unknown objects, most likely glacial dropstones.

Hole U1339A

Hole U1339A was spudded at 0430 h on 17 July (all times are ship local time, Universal Time Coordinated [UTC] – 11 h). The first core was shot with the bit at 1873 m drilling depth below rig floor (DRF), recovering the mudline and 4.94 m of core. The hole was terminated after Core 323-U1339A-4H when a suspected bottom-hole assembly (BHA)/coring system problem resulted in almost 100,000 lb of overpull on the last core. The drill string was tripped out of the hole, the coring system components were inspected, and several parts were changed. No conclusive evidence of the mechanical problem was found. The BHA was run, and the coring system was tested successfully in the water column.

Hole U1339B

The vessel was offset 20 m, the rest of the string was tripped to the seafloor, and Hole U1339B was spudded at 2315 h on 17 July. The first four cores (323-U1339B-1H through 4H) were dedicated to microbiology, and both PFT and whirlpack bags were deployed. Coring in Hole U1339B recovered the sedimentary sequence from the total depth of Hole U1339A to 196.0 m DSF. One short core (323-U1339B-13H) was recovered when the APC fired into an unknown object, most likely a glacial dropstone. The nonmagnetic core barrel was replaced with a steel core barrel when resistance became exceedingly high in Core 323-U1339B-19H. Hole U1339B was cored to 196.0 m DSF, and coring ended at 2010 h on 18 July when the bit cleared the seafloor.

Hole U1339C

The vessel was offset 28 m, and Hole U1339C was spudded at 2230 h on 18 July. The first core was >9.5 m long but contained the mudline at its top. Core advance was a continuous 9.5 m except for Core 323-U1339C-16H, which contacted an apparent dropstone at 4.5 m. The nonmagnetic core barrel was used through Core 323-U1339C-17H, and APC coring proceeded with a steel core barrel through Core 323-U1339C-21H to 194.8 m DSF. The drill string cleared the seafloor at 1610 h on 19 July, officially ending Hole U1339C.

Hole U1339D

The vessel was offset 28.3 m, and Hole U1339D was spudded at 1724 h on 19 July. Core 323-U1339D-1H was 6.6 m long. All successive cores were 9.5 m long, with the exception of one short core that resulted from premature firing of the APC. The nonmagnetic core barrel was used through Core 323-U1339D-17H, and APC coring proceeded with a steel core barrel through Core 323-U1339D-22H to 200.0 m DSF. Rig-up for wireline logging in Hole U1339D started at 1130 h on 20 July. The triple combination (triple combo) and Formation MicroScanner (FMS)-sonic tool strings were deployed, and both obtained good data. The drill string was pulled and secured for transit. Transit to IODP Site U1340 began at 0745 h on 21 July.

In all, APC coring for Site U1339 totaled 69 cores, 642.2 m penetrated, and 644.75 m recovered, for 103.1% core recovery.

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