Leg 195 began in Guam harbor with the first line ashore at the fueling depot at 1600 hr on 2 March 2001. Upon completion of refueling activities, the ship was moved to Ammunition Berth Hotel for the remainder of the port call.
Port call activities, aside from the normal loading and off-loading of freight, included the loading of International Ocean Network (ION) equipment directly shipped from Japan and the equipment stored in Guam after Leg 191. In addition, special hardware required to support the installation of a CORK at Site 1200 was loaded. The night before the departure, Catermar hosted a barbecue on the dock for the entire ship's complement as an ice breaker.
At 1300 hr on 7 March, the JOIDES Resolution left the dock and got under way at full speed for the first automated station-keeping (ASK) test site. After only 36 min under full steam, the ship suffered a massive power failure at 1405 hr that left the ship in not-under-command condition. Minimum propulsion was returned at 1415 hr by switching to manual engine control governors. The vessel was able to return to port for repair and readjustment of the electronic engine control governors. First line was ashore at 1617 hr at Berth 5 in Guam harbor, where system repairs immediately commenced.
At 0700 hr on 8 March 2001, the ship officially departed Guam for the second time. The vessel transited 54 nmi to a deepwater (~6300 m) test site, arriving on location at 1235 hr. This commenced a 48-hr sea trial of the ASK system. At 0209 hr on 9 March, the vessel departed the deepwater location and transited 40 nmi to an area selected as a site for shallow-water (<300 m) sea trials. The shallow-water testing was concluded, and the beacon was retrieved at 0845 hr on 10 March. The vessel got under way for the Guam pilot station, where the ASK test engineers departed. By 1130 hr on 10 March, the ship was under way at full speed for Site 1200 (proposed Site MAF-4B). The transit of 95 nmi was completed in 9.5 hr at an average speed of 10 kt.
At 2100 hr on 10 March, the vessel arrived at the first location of Leg 195, and the thrusters and hydrophones were lowered. A positioning beacon was not immediately deployed, and the ship maintained station keeping by using the Global Positioning System. A brief 12-hr camera survey of the site was conducted to spot a locality that showed evidence of fluid migration to the surface (see "Video Camera Survey"). At 0710 hr on 11 March, the first positioning beacon was deployed. When this beacon failed to respond to actuation commands, the ship was moved 200 m upcurrent and at 0832 hr a second beacon was deployed. A total of 15.25 hr was spent investigating the site and identifying prospective drilling locations, of which 1.5 hr was spent conducting a 23-m jet-in test at the future reentry hole location ("C" in Fig. F3; Table T1).
After returning to the locality identified for the first coring attempt (Fig. F3), the vibration-isolated television (VIT) was recovered and the first pilot hole, Hole 1200A, was spudded with the RCB system at 2200 hr on 11 March. The seafloor was tagged at a depth of 2921.0 meters below rig floor (mbrf). Coring continued through Core 195-1200A-10R to a depth of 89.4 mbsf (Table T1). Recovery was poor, with little recovery of the serpentine mud matrix material surrounding the hard ultramafic clasts typical of the site. Because of steadily increasing torque, a short wiper trip was made before the top of the bottom-hole assembly (BHA) went below the seafloor. Coring continued through Core 195-1200A-13R to a depth of 118.3 mbsf, where once again the rotating torque increased. During recovery of Core 195-1200A-13R, the top drive stalled and the drill string became stuck. After 30 min the pipe was worked free and RCB coring resumed. Core 195-1200A-16R was cored to a depth of 147.2 mbsf, where a repeat of the earlier stuck-pipe incident occurred. Once again, high torque and lost rotation resulted in a stuck drill string. The pipe was worked free, and another wiper trip to 30 mbsf was initiated. The drill string drag during the trip was fairly constant, except for a zone around 45 mbsf that continued to be troublesome. It was apparent that the hole could not be salvaged, and the drill string was pulled out of the hole. The seafloor was cleared at 1535 hr, ending Hole 1200A. One wash barrel "ghost" core (195-1200A-17G) recovered 2.66 m.
The ship was offset 25 m to the east, and Hole 1200B was spudded at 1640 hr on 13 March, with the seafloor tagged at a depth of 2922.0 mbrf. Our intention was to drill ahead with an RCB wash barrel in place to 147.2 mbsf, the total depth (TD) achieved in Hole 1200A. By 0615 hr on 14 March, the hole had been advanced to a depth of 98.0 mbsf. As in Hole 1200A, the penetration rate was variable as the bit alternately encountered soft serpentine mud and then hard clasts. Overall, the average rate of penetration (ROP) for the interval was 11.0 m/hr.
Once again, high torque and overpull began to plague the hole. Regardless of consistent mud sweeps and multiple reaming attempts, the hole would not clean up. At 0645 hr on 14 March, it was decided to abandon further drilling/coring efforts and the drill string was pulled out of the hole. Overpulls of up to 120 kilopounds (kips) were required before finally clearing the seafloor at 0730 hr. The wash barrel was recovered, and at 1430 hr on 14 March the bit cleared the rig floor, ending Hole 1200B.
Because of the difficulties in drilling Holes 1200A and 1200B to the target depth, a variance from the Pollution, Prevention, and Safety Panel was requested to allow setting the 10.75-in surface casing string in the planned reentry hole to a depth of 250 mbsf (hole depth = ~270 mbsf), more than 100 m beyond the cored depth of 147.2 mbsf. This request was approved expeditiously because the formation at this site was not likely to change with depth.
The ship was offset 125 m north and ~25 m west to the location where the jet-in test had been conducted. The reentry cone had previously been assembled and pre-positioned onto the moonpool doors. The 20-in casing shoe joint had already been precut and the casing shoe welded in place. Two joints of 20-in casing were connected to the 20-in casing hanger, and this assembly was lowered and latched into place using the Dril-Quip (DQ) running tool.
An 18.5-in tricone mill-tooth bit with an underreamer dressed with 22-in cutter arms was made up to an 8.25-in positive displacement mud motor. Rig-floor testing of this assembly was initiated at 10 strokes per minute (spm), and the underreamer arms began to open up at 15 spm.
Hole 1200C was spudded at 0450 hr on 15 March, as the bit tagged the seafloor at a depth of 2943.0 mbrf. Progress was slow and variable, but the casing kept advancing using steadily increasing weight on bit up to 25 kips and total flow rates as high as 150 spm using two mud pumps. After 18.25 hr, the reentry cone base reached the seabed, placing the 20-in casing shoe at 23.7 mbsf and the bit at 25.9 mbsf. The DQ running tool was released, and the drilling assembly was tripped back to the ship, where it cleared the rig floor at 0530 hr on 17 March.
The next BHA consisted of the same 18.5-in tricone drill bit and underreamer combination but without the mud motor. The BHA was tripped to the seafloor, and after deploying the VIT, Hole 1200C was reentered for the first time at 1720 hr. The drilling assembly advanced smoothly. Penetration rates varied from 3 to 10 m/hr as the hole was advanced. All drilling parameters remained consistent, and no problems were experienced throughout the course of drilling. At 0130 hr on 18 March, the hole reached a TD of 3083.0 mbrf (140 mbsf). A sepiolite mud sweep was pumped while on bottom, followed by a wiper trip to 20.0 mbsf and back to TD. Hole conditions were good, and the driller indicated no overpull, drag, or torque problems during the trip. Eight meters of soft fill at the bottom was circulated out with another sepiolite mud sweep. The hole was displaced with 215 bbl of sepiolite, the top drive was set back, and the drill string was recovered back aboard ship, clearing the rig floor at 1130 hr on 18 March.
Hole 1200C was reentered for the second time at 2337 hr with the DQ running tool and nine joints of 16-in casing and a casing hanger. While the casing string was being washed/lowered into the hole, however, the casing shoe encountered an obstruction 6 m off the bottom, which prevented the casing hanger from landing. After three futile hours, the string was recovered back to the ship and one joint of casing was removed from the string.
The shortened string was run back into the hole, and the hanger was landed at 2100 hr on 19 March without incident. With the 16-in casing shoe placed at a depth of 107.4 mbsf, the casing string was cemented in place. The cementing equipment was laid out, and the drill string was recovered. The DQ tool was laid out, and the 18.5-in bit and underreamer were replaced with a 14.75-in bit. The drill string was run back in, and the fourth reentry was made at 1329 hr on 20 March. The cement column was drilled out, and the hole was deepened to 152.0 mbsf. The drill string was recovered, and an underreamer dressed with 20-in cutter arms was placed above the 14.75-in bit. The drill string was run back in, and the fifth reentry was made at 1015 hr on 21 March. Drilling resumed, and after advancing to 266.0 mbsf at 2245 hr on 22 March, the ROP went to zero. A wiper trip to the seafloor was initiated. At a depth of 237.0 mbsf, the pipe became stuck but was worked free within 15 min using 50 kips of overpull. The pipe trip continued to the 16-in casing shoe at 107.0 mbsf, and then the hole was washed/reamed back to 257.0 mbsf. The 9 m of soft fill was easily circulated out of the hole, but further deepening proved futile and the drill string was recovered for inspection. The bit was found to be in good condition with only a few chipped/broken teeth, but the underreamer was missing two out of three cutters.
Four joints of 10.75-in screened/perforated casing totaling 53.5 m in length were made up. The lowermost joint was terminated with a conventional cementing float shoe. The screened joints were followed by 14 joints of standard 10.75-in casing. At 2210 hr on 23 March, Hole 1200C was reentered, and by 0300 hr on 24 March, the casing had been advanced to a depth of 224.0 mbsf. Progress beyond this point was prevented, and the 10.75-in string was pulled out of the hole and tripped back to the drill ship, where it was decided to remove three joints of casing.
By 1458 hr on 24 March, the string had been tripped back to bottom and the casing was run in the hole without incident. The casing hanger was landed, latch engagement was verified, and the DQ tool was released by 1610 hr. The shortened casing string placed the shoe at 202.8 mbsf, with the screened interval extending from 202.3 to 148.8 mbsf.
Prior to withdrawing the drill string from the hole, the water sampler temperature probe was deployed in an attempt to sample some of the borehole fluids. Water sample and temperature data were collected from a depth of 30 mbsf, and the tool was recovered back to the ship.
The CORK assembly (see "Borehole Instrumentation"), with six joints of 5.5-in drill pipe used as a stinger, was run in the hole at 0954 hr on 25 March, and the drill string was lowered to 53.0 mbsf. This left the CORK temporarily shy of landing out by ~8 m.
The thermistor string was deployed with two osmotic fluid samplers and an aluminum pin used in the shackle connecting the sinker bar weight. This "weak link" was designed to corrode over time, allowing the thermistor string and osmotic samplers to be recovered at a future date without having to recover the sinker bar weight.
At 1300 hr on 25 March, the thermistor/osmotic sampler assembly was slowly run into the hole, and at 1430 hr, the data logger was landed in the CORK body. One hour was taken at this point to calibrate the seafloor pressure sensor with the internal CORK pressure sensor. At 1530 hr, the drill string was pressured up and the data logger was latched into the CORK assembly. After using the wireline jars to shear the overshot shear pin, the wireline was recovered.
At 1630 hr, the CORK setting go-devil was deployed and the CORK was landed in the reentry cone structure. The drill string was pressured up, but before reaching the specified 1000-psi setting pressure, the shear pins on the internal bypass feature sheared at ~900 psi. The go-devil was recovered, redressed with a solid plug, and redeployed. Once landed, the drill string was pressured up to 1000 psi and held for 2 min. The standpipe was bled off and the drill string picked up, verifying that the CORK was not latched in. The CORK was landed once again, and the drill string was pressured up to 1500 psi and held for 3 min. The CORK latch mechanism still did not engage, so the drill string was pressured up a third time. This time, pressure was increased to 2000 psi for 5 min and then to 2500 psi for another 5 min. After bleeding off the pressure at the standpipe, the pipe was raised, and CORK latch verification was achieved at 2000 hr on 25 March.
The remotely operated vehicle (ROV)/submersible platform halves were moved onto the moonpool doors and bolted and welded around the drill string. At 2200 hr on 25 March, the platform was lowered into the water and released. This was followed immediately with the VIT. At 2315 hr, the platform was observed resting properly in place over the reentry cone/CORK body. The active heave compensator contributed greatly to a successful CORK landing and releasing operation. While the coring line was run in to retrieve the CORK setting go-devil, the VIT was retrieved and the drill string was recovered. The rig floor was cleared at 0500 hr on 26 March, ending operations at Hole 1200C.
The vessel was offset 40 m south of Hole 1200C. The VIT was deployed during the pipe trip to enable location of an appropriate spud position. Hole 1200D was spudded at 1415 hr on 26 March. Water depth was identified as 2942.0 mbrf, based on a visual tag with the drill bit, and the VIT was recovered. APC coring was initiated and continued to a depth of 44.4 mbsf using the APC advance-by-recovery method. When hard clasts were encountered, an XCB center-bit assembly was deployed to drill through clasts until breaking out into soft material. Then APC coring was resumed. This occurred a total of four times, between Cores 195-1200D-4H and 5H, 5H and 6H, 9H and 10H, and immediately after 10H. For microbiological contamination control, Whirl-Pak microspheres were deployed, starting with Core 195-1200D-4H, and perfluorocarbon tracers (PFT) were pumped starting with Core 1H. After Core 195-1200D-10H was terminated by a hard clast, the XCB center bit was used to deepen the hole. After advancing 9 m the ROP fell to zero, and it was feared that the XCB cutting shoe/center bit had failed. Once recovered, the XCB barrel was found to be intact, with the cutting structure unharmed. This suggests that the drill bit was pushing a hard clast downhole ahead of the bit. As a result, the decision was made to abandon Hole 1200D. The hole was displaced with heavy mud. The top drive cleared the seafloor at 1230 hr on 27 March, officially ending Hole 1200D.
The ship was moved back to the coordinates of Hole 1200A, and at 1515 hr on 27 March, Hole 1200E was spudded using a visual seafloor tag depth of 2922.0 mbrf. APC coring was initiated and continued using the advance-by-recovery method through Core 195-1200E-6H, to a depth of 25.9 mbsf. The Davis-Villinger temperature probe (DVTP) was unsuccessfully deployed in an attempt to recover a temperature measurement. APC coring continued through Core 195-1200E-7H to a depth of 32.5 mbsf, where the XCB coring system was deployed to drill through a hard clast. Two XCB cores were recovered after some very slow drilling to a depth of 50.4 mbsf. Core 195-1200E-10H was recovered using the APC, advancing the hole to 56.4 mbsf. At this depth, a second DVTP temperature measurement was attempted, again without success.
The scientific objectives for this hole had been accomplished, and the drill string was thus pulled clear of the seafloor, officially ending Hole 1201E at 1115 hr on 28 March.
The ship was offset 20 m north, and Hole 1200F was spudded at 1315 hr on 28 March. Coring proceeded until the time allocated for operations at Site 1200 expired. Hole 1200F reached a depth of 16.3 mbsf, with the recovery of APC Cores 195-1200F-1H through 3H. An Adara temperature measurement taken with Core 195-1200F-3H was excellent. No PFT tracers or Whirl-Paks were used during the operations at this hole. The drill string was recovered back to the ship, and all BHA components were laid out. The bit cleared the rotary table at 2315 hr on 28 March. The ship was secured for transit while the positioning beacons were released and recovered. At 0200 hr on 29 March, the ship was under way for the Guam pilot station.
A camera survey was conducted at Site 1200 prior to drilling. The objective was to locate the sites of active vent fluid springs (position 1 in Fig. F3), as identified by the presence of carbonate encrustations and chimneys and by the presence of mussel beds and other megafauna (snails, worms, and galatheid crabs).
The VIT was deployed while pipe was tripped to a depth of ~2920 m. The bottom was first observed at ~0615 hr. When the first positioning beacon failed to respond to actuation commands, the ship was moved 200 m upcurrent (east) and a second beacon was deployed (position 2 in Fig. F3). The ship was then moved farther west to the starting reference position (positions 1 and 3 in Fig. F3) to begin the survey, and as it moved, white patches (carbonate encrustations) were observed ~50 m from the east end of the beacon drop line. At 44 m east of the reference position, the seafloor was fissured.
When the ship had returned to the reference starting position (positions 1 and 3 in Fig. F3), we began a traverse on a heading of 045° for 200 m (to position 4 in Fig. F3). The seafloor is covered with rock clasts and serpentine mud along this traverse, and the depth increased slightly before decreasing to a shallower area of small (1-2 m) crags of serpentine mud with numerous rock clasts. This texture persisted over most of the traverse. At a distance of 94 m along the traverse from the reference starting point, the seafloor had fine fissures and fewer clasts. At ~190 m from the starting point, the seafloor became rockier and deepened by a few meters.
At position 4 (Fig. F3), the ship began an east-to-west transect for another 200 m to position 5 (Fig. F3). During this traverse, the seafloor rose slightly at first to ~2882 m then dropped off a few meters for the rest of the transect. Depth increased consistently, although only slightly, to a maximum depth of 2903 m. The summit depression appears to have a north-south elongation. The area within the depression, especially at the western end of the transect, has fewer and smaller rock clasts. As the ship reached the western end of the line, the seafloor had higher albedo and fewer rock clasts and, thus, was deemed appropriate for the reentry hole (Hole 1200C).
The next line of the survey was run southward to latitude 13°47.00´N along ~146°48.00´E (position 6 in Fig. F3). At 13°47.0120´N, white specks (interpreted as shells of dead mussels) were observed scattered over the seafloor. At ~13°46.9987´N, we observed white patches of carbonate encrustations and high albedo patches interpreted to be fresh exposures of serpentine mud. The marker left at the end of Shinkai 6500 dive 351 was observed shortly afterward, and beds of live mussels, holes where cores had been taken previously, and white carbonate encrustations and small chimney structures were observed at ~13°47.0027´N, 146°00.1751´E. The bottom was tagged at a depth of 2920.7 m.
It was decided to conduct the jet-in test for the reentry hole near position 5 (Fig. F3) and then to return to the Shinkai springs site to drill the pilot hole. The ship was moved back to the jet-in test site at 13°47.0705´N, 146°00.1754´E, and the jet-in test was initiated. Mud emanating from the jet-in hole was high albedo serpentine mud initially, but turned dark shortly after the test began. This suggested that the oxidized lighter serpentine mud was present to a meter or so beneath the seafloor and was underlain by darker reduced mud. The jet-in test was completed at ~1500 hr.
The ship was moved back to the location of the spring site that was chosen for Hole 1200A, and after a box survey, the area of white carbonate chimneys was detected at a depth of 2921 m at 1932 hr. Shortly afterward, areas of patchy carbonate, the Shinkai 6500 marker, and the mussel beds were relocated. The position for Hole 1200A was chosen to be within the Shinkai springs area but offset from the mussel beds in an effort to preserve these communities for future studies while optimizing the potential for recovery of cores that would yield good pore fluids for geochemical studies.