Site 1160 | Table of Contents
SITE 1159

Transit to Site 1159
The eighth site of Leg 187 is 133 nmi southeast of Site 1158. We conducted a 3.5-kHz and SCS survey at ~6 kt during the entire transit. The purpose of this survey was to locate additional drilling targets on a line between Sites 1158 and 1159.

Hole 1159A
We deployed a positioning beacon on the prospectus site GPS coordinates at 2208 hr on 18 December. The PDR water depth for this site is 4515.4 mbrf. The nine-collar BHA used on the other sites was reassembled, using the same C-7 four-cone rotary bit from the previous site. We began washing through the sediment column at 0645 hr on 18 December and reached basement at 145.6 mbsf in just over 2 hr. After recovering the wash barrel (Core 187-1159A-1W), we advanced by coring from 145.6 to 173.3 mbsf (Cores 187-1159A-2R through 7R). Hole conditions deteriorated rapidly while we were drilling Core 187-1159A 7R, as indicated by a sudden increase in penetration from ~2 m/hr to >10 m/hr. We abandoned the hole when we were unable to regain our previous sub-bottom depth because of fill in the hole. Core 187-1159A-8G was recovered but represents no new penetration. The rocks recovered in this core do not appear to have been cut by the bit, and we interpret them as rubble fallen into the hole and collected during the hole cleaning attempt. A tracer of fluorescent microspheres was deployed on Core 187-1159A 2R. The drill string cleared the seafloor at 1115 hr and the rotary table at 1945 on 20 December, ending operations at this site.

Site 1160 | Table of Contents