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doi:10.2204/iodp.proc.347.111.2015 OperationsTransit to Hole M0067AFollowing completion of Hole M0066B, the Greatship Manisha commenced transit to Site M0067 (proposed Site BSB-4), located in Little Belt. The vessel commenced transit at 0515 h on 27 October 2013 and arrived on site over Hole M0067A at 0830 h on 28 October. Hole M0067AFollowing arrival, a dynamic positioning model was established and coring operations commenced in Hole M0067A (Table T1). The first piston corer system (PCS) run recovered clay, but subsequent cores consisted of gravel and sand-grade material, which was an unexpected lithology at this depth. While attempting to wash down to 12 meters below seafloor (mbsf) to take a hammer sample, a change in drilling parameters was noted at a depth calculated to be 9.3 mbsf. At this time (1245 h on 28 October 2013), the winds escalated rapidly and the ship was blown off position, bending the string. The driller was able to trip one pipe off the string and sky the remainder to make the string and vessel safe. The template was brought back on deck, and the drill deck was made secure. Much of the remainder of the day was spent waiting on weather (winds peaked at Force 12 for >4 h). A total of seven cores were recovered to 9.3 mbsf. Hole recovery was 56.34%. Hole M0067BWhen the winds dropped to safe working levels at 2140 h on 28 October 2013, the vessel repositioned over Hole M0067B, and coring operations in this second hole began. This hole extended to 10.9 mbsf using a combination of PCS and open holing in an attempt to assess the extent of the gravel. At this depth, the hole was terminated in a gravel and fine sand lithology. This lithology was not anticipated and was therefore not consistent with the scientific aims for the site. Also, the gravel was liable to cause hole stability issues should the hole have continued to greater depth. A total of five cores were recovered from Hole M0067B to 10.9 mbsf, with one open-hole section. Hole recovery was 97.03% when the open-hole section was discounted. |
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