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doi:10.2204/iodp.proc.347.110.2015 OperationsTransit to Hole M0066AFollowing completion of Hole M0065C, it was decided that the alternate site should also be cored (1.4 km to the east) to capture the lower till stratigraphy in a location where the upper sequence was condensed, bringing the lower sequence within coring range. It was inferred from the seismic data that the stratigraphy at the alternate site consists of a shorter upper clay sequence; therefore, the target depth for holes at Site M0066 was set at 25 m. The vessel arrived on site at 0723 h on 26 October 2013, and operations commenced (Table T1). Hole M0066APrior to drilling, it was necessary to conduct a camera survey over the locations for Holes M0066A and M0066B to assess the presence of any chemical contaminants at the surface. Again, additional personal protective equipment (PPE) was worn for the first run (after washing down the uppermost 2 m). The first piston corer system (PCS) core was recovered to deck at 0845 h on 26 October 2013. Coring continued throughout the day using the PCS, nonrotating core barrel (NRCB), and hammer sampler because the stratigraphy showed considerable variability between clay, sand, silt, and diamicton. The hole ended at 28.0 meters below seafloor (mbsf) following recovery of sand in Runs 19–21. A total of 18 cores were recovered from Hole M0066A, with three further open-hole sections. Hole recovery was 76.82% when the open-hole sections were discounted. Hole M0066BFollowing completion of Hole M0066A, the vessel moved under dynamic positioning to commence operations in Hole M0066B. Additional PPE was worn for the first run, as previously detailed, following washing down of the uppermost 2 m. The aim of Hole M0066B was to achieve a composite recovery record with Hole M0066A, so specific intervals were targeted using a combination of push coring assembly, NRCB, and piston coring. The first core was recovered at 1955 h on 26 October 2013, and coring continued to 27 October with the final core recovered at 0250 h. The vessel then prepared for transit to Site M0067. A total of nine cores were recovered from Hole M0066B, with a further five runs drilled using the NRCB or noncoring assembly. The hole reached a maximum depth of 27.85 mbsf. Hole recovery was 78.61% when open-hole sections were discounted. |
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