Daily Science Report 38 -- Tuesday, 18 January 2011
| Reports |
Location
After 133.5 hours of bit rotation drilling in Hole U1347A terminated this morning. To everyone’s delight, Cores U1374A-71R, -72R and -73R (513.1-522.0 mbsf) retrieved predominantly lava flows (and only minor intervals of volcanoclastic breccia) with 81% recovery. Advancement for the last Core -73R had to be stopped after only 1 m (due to beginning bit failure) and retrieved 88 cm of basalt. Curiously, its recovery of 88% reflects exactly the overall recovery for this amazingly successful hole. The beginning of the downhole logging program was delayed due to the failure of the mechanical bit release mechanism to drop the drill bit at the bottom of the hole. This required the retrieval of the entire drillstring and re-entering of Hole U1347A with a specialized logging bit. However, this provided the opportunity to shorten the bottom hole assembly (the heavier, lowermost part of the drill string that needs to remain in the upper part of the hole during logging). With the shorter configuration more open hole (below the end of the drill string) is available for logging. The extensive logging program scheduled for this site will enable scientists and technical personal to catch up with core processing and description.
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