Site 1164 | Table of Contents
SITE 1163
Transit to Site 1163
The west-northwest transit from Site 1162 to Site 1163 took about 10
hr at an average speed of 10.4 kt. At 2330 hr on 31 December, we slowed
to 5 kt and ran a south-to-north SCS survey on a line 1 nmi west of and
parallel to the precruise site survey track. Since the valley hosting the
sediment-filled pond (our prospectus site) opened to the west, we hoped
that we would find a more inviting drilling target along this line. When we
could find no suitable sediment cover along this survey track, we steered
a southeasterly heading, which carried us directly over the GPS
coordinates of the prospectus site. Although the sediment pond is a small
target at this location, we decided that the sediment thickness was
sufficient to provide lateral support for the BHA. Although the duration of
the survey was only 1.6 hr and covered 8 nmi, it had the distinction of
lasting from one millennium to the next.
Hole 1163A
The PDR water depth referenced to the DES at this site is 4365.4 m. The
nine-collar BHA employed at the other sites was reassembled, along with
a previously used hard-formation C-7 four-cone rotary bit that was still
in good condition. This bit was run with a mechanical bit release. We
began Hole 1163A at 1030 on 1 January by washing through ~160 m of
sediment below seafloor at an average penetration of 54 m/hr. When the
driller noted a hard contact, we pulled the wash barrel (Core 187-1163A
1W, 0.0 to 161.0 mbsf). We advanced Hole 1163A by rotary coring
161.0-208.1 mbsf (Cores 187-1163A-2R to 11R) with generally good
drilling conditions and 33% recovery. Microsphere tracers were deployed
on Core 187-1163A-2R. We terminated operations at this site when we
reached our depth objective of ~50 mbsf. The drill string cleared the
seafloor at 2345 hr on 2 January and the rotary table at 0700 hr on 3
January.
Site 1164 | Table of Contents