The seafloor depth was established at 2996.7 mbrf in Hole 1059A. Hole 1059B is ~28 m southwest of Hole 1059A, and Hole 1059C is another ~30 m southwest of Hole 1059B. The starting drill string position was vertically offset 3 m shallower for Hole 1059B than Hole 1059A and then another 2 m shallower for Hole 1059C. By 1424 hr on 5 March, the vessel was underway to Site 1060.
Drilling operations at Site 1060 began at 2253 hr on 5 March. All holes were APC cored with recovery ranging from 84% to 108%, with a site average of 104%. The Tensor tool was used to orient Cores 1060A-3H through 11H, but sustained water damage and no data were retrieved. Thus, no cores were oriented at this site.
The seafloor depth was established at 3481.2 mbsl in Hole 1060A, which was 8.4 m shallower than the PDR depth. APC coring advanced without incident to a total depth of 170.0 mbsf. Hole 1060B is ~22 m southwest of Hole 1060A, and Hole 1060C is another ~32 m southwest of Hole 1060B. The starting drill string position was 3 m lower for Hole 1060B than Hole 1060A, and then another 3 m lower for Hole 1060C. By 0400 hr on 8 March, drilling operations were completed at Site 1060 and the vessel was underway to Site 1061.
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At 1325 hr on 8 March, a beacon was deployed at the new site, and at 1153 hr on 9 March, a second beacon was dropped as a backup. Five holes were drilled at Site 1061 with core recovery exceeding 100% at all holes except 1061A.
From the first APC core at Hole 1061A, the seafloor depth was estimated as 4046.6 mbsl, which was 8.9 m shallower than the PDR (3.5 kHz) depth. Later, after examining the upper cores from other holes at this site and the downhole logging measurements, we confirmed that Core 1061A 1H did not capture the mudline. The top of the core was instead ~11 m below the mudline, thus indicating the PDR depth was probably off by ~20 m.
APC coring advanced in Hole 1061A without incident to 152.0 mbsf, which was considered to be APC refusal. Cores 1061A-3H through 8H and 10H through 16H were oriented, although no other cores were oriented at this site because there was only one operational Tensor orientation tool. Coring resumed with the XCB and advanced to a total depth of 350.3 mbsf by 1630 hr on 10 March.
In preparation for logging, the hole was flushed with a 30-bbl sepiolite (drill mud) sweep and the drill string was pulled back to 308 mbsf and then up to 68 mbsf, with a maximum drag of 20 kips. When the drill string was run back to the bottom of the hole, it contacted only 2 m of soft fill. The hole was cleaned with 162 bbl of 8.9 ppg sepiolite mud. The drill string was pulled up and the bit positioned at the logging depth of 93 mbsf.
By 2330 hr on 10 March, the Schlumberger equipment was prepared and the first logging tool (Triple-combo Suite-DITE [digital dual induction tool], HLDT [slim-hole lithodensity logging tool], APS [accelerator porosity sonde], HNGS [hostile environment natural gamma-ray sonde]) was run in the drill pipe. The logging tool went almost to bottom with no apparent problems and the hole was successfully logged from 348 to 77 mbsf, and then from 350 to 262 mbsf on a second pass. The final log consisted of two passes with the Formation MicroScanner (FMS), SDTC (sonic digital logging tool), and NGTC (natural-gamma spectrometry tool) combination, which was run in the hole from 338 to 73 mbsf. The diameter of the hole was found to vary from 28 to 38 cm (11 to 15 in) and the angle of the hole was less than 2° from vertical. The quality of the logging data were considered to be very good.
At 1606 hr on 11 March, Hole 1061B was spudded 36 m north of Hole 1061A, and the drill string was positioned 3 m higher. The first APC core recovered a full barrel, and so the hole was abandoned. The bit was picked up to 4044.5 mbrf and Hole 1061C was spudded ~4 m to the south of Hole 1061B. Based upon the mudline recovery, the seafloor depth was established at 4036.9 mbsl. APC coring advanced to an APC refusal depth of 166.8 mbsf.
Hole 1061D was spudded ~32 m north of Hole 1061C, and the bit was positioned 3 m higher than at Hole 1061C. The seafloor depth was estimated at 4038.4 mbsl. APC coring advanced to 162.7 mbsf, which was just below the APC refusal depth of Hole 1061C. The hole was then deepened with the XCB to a total depth of 180.0 mbsf.
Hole 1061E was spudded ~44 m north and 6 m west of Hole 1061D, with the bit positioned at 4047.0 mbrf, about 2.5 m deeper than at Hole 1061C. The hole consisted of only two piston cores, which were cored to insure that a complete record of the Holocene and upper Pleistocene section was recovered.The drill string was pulled out of the hole and cleared the seafloor at 1100 hr on 13 March. By 1845 hr on 13 March, drilling operations were completed and the vessel was underway to Site 1062.
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To 172 Operations: Sites 1062-1064
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