The 1027-km transit from Site 1136 to Site 1137 was made in 57 hr at an average speed of 9.7 kt. The ship arrived at Site 1137 on New Year's Eve, 31 December 1998. Weather conditions upon arrival were quite mild compared to those at departure from the last site. At 2100 hr on 31 December 1998, we deployed a beacon on the precise Global Positioning System (GPS) coordinates for Site 1137.
We spudded Hole 1137A at 0215 hr on 1 January 1999 using the rotary core barrel (RCB) coring assembly and an RBI C-4 core bit. Accurate identification of the seafloor is quite difficult with the RCB system. The driller reported some weight loss around the 3.5-kHz precision depth recorder depth of 1020.4 mbrf. The bit was advanced a full 9.5 m from the last connection at 1016.0 m, and, when recovered, the core barrel had 9.62 m of recovery. Because an accurate seafloor depth was not considered essential to the science objectives, we did not take the time to attempt recovering mudline. Coring continued with a seafloor depth adjusted to the rig floor of 1016.0 m below rig floor, equivalent to 1004.5 m below sea level.
Continuous wireline coring proceeded in homogenous white foraminifer-bearing nannofossil ooze through Core 183-1137A-21R to a depth of 1215.5 m (199.5 meters below seafloor [mbsf]). No chert was encountered. Recovery for this interval averaged 53.8% but was highly variable, ranging from 0% to 108%. A summary of core numbers, depths, and recovery is given in Tables T1 and T2. The average rate of penetration (ROP) was 40.1 m/hr. The formation then became glauconite-bearing sandy packstone with abundant shell fragments until contacting basement at ~1240 m (~224 mbsf). The average recovery in this 24.5-m interval was an extremely poor 10.7%, and the average ROP dropped to 30.5 m/hr. Basement consisted of a series of basalt flows interspersed with volcaniclastic sandstone, conglomerate, and crystal-vitric tuff.
After recovering Core 183-1137A-37R from 327.5 mbsf, a short trip was made to recover five knobby drilling joints. This was to enable the drilling depth objective of 374.0 mbsf to be reached using knobby joints. These joints were required because of the slow ROP and frequent severe sea states experienced while on site. Upon returning to bottom, ~1.3 m of hard fill was found. While attempting to ream through this material, the weather and sea state continued to deteriorate to the point where the heave compensator was exceeding its stroke length. In addition, the yellow (2%) dynamic positioning warnings were becoming more frequent. The pipe was pulled to the top of the hole and hung off using knobby joints at a depth of 1336.0 m (320.0 mbsf). After waiting on weather for 6.75 hr, the weather conditions moderated and the pipe was run back to bottom. Only 30 min was required to clean out the hole, and coring resumed. Coring was terminated with Core 183-1137A-46R at a total depth of 371.2 mbsf. This was ~150 m into basement and satisfied the scientific depth objective for this site. Average recovery in basement was 69.2%, but recovery was quite variable, ranging from 19% to 102%. A total of 14 half cores were cut to maximize recovery. The overall ROP averaged 4.5 m/hr; however, it varied considerably from 5.5 to 1.7 m/hr.
A wiper trip was initiated to prepare the hole for wireline logging; however, this was halted because of deteriorating weather conditions when the pipe reached a depth of 120.3 mbsf. After waiting on weather for 10.75 hr, the wiper trip was completed. The hole was swept with a 25-bbl sepiolite mud pill, the bit released, and 112 bbl of sepiolite mud was displaced into the hole for logging. The pipe was pulled to a depth of 100.3 mbsf, and preparations for logging began. The first logging run was with the triple combo suite of tools, which includes the dual laterolog (DLL) for resistivity, the accelerator porosity sonde (APS) for porosity, and the high-temperature lithodensity tool. Also included in this tool string was the hostile-environment natural gamma-ray sonde (HNGS) and the Lamont-Doherty Earth Observatory (LDEO) high-temperature/acceleration/pressure tool (TAP). This run was very successful, reaching a depth of 367.0 mbsf (~4 m above bottom). The next run was with the Formation MicroScanner (FMS) and dipole shear sonic imager (DSI) tool suite. A natural gamma-ray tool was included for calibrating between logging runs. This deployment was also very successful, reaching the same depth as the first run. During the second pass with the FMS-DSI, the tool would not pass a tight spot at ~174 mbsf. Unfortunately, the tool was stuck at that point, requiring ~3,500 lb of force to pull it free. In looking at the FMS caliper log, it appeared that a fairly large portion of the hole (~75 m) had closed in significantly, in places to a diameter of ~4 in. Because it was not likely that the well seismic tool would pass this spot, the remainder of the wireline logging program was canceled for this hole. Opening up the hole with open-ended pipe was unlikely to be successful and would have put the drill string and bottom-hole assembly at risk.
While the drill string was being recovered, several attempts were made to release the positioning beacon. While it acknowledged the commands, on each occasion the beacon failed to release and was ultimately left on the seafloor. The pipe trip was completed when the mechanical bit release reached the rig floor at 1645 hr. The ship was immediately secured for transit, and, at 1645 hr on 6 January 1999, we were under way for Site 1138.