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Expedition 321 was the second of two expeditions that comprise the PEAT science program. Expedition 321 began in Honolulu, Hawaii, and drilled eight holes at two sites (U1337 and U1338) (Table T1) before returning to San Diego, California.
Expedition 321 officially began at 0736 h on 4 May 2009, with the first line ashore Pier 2B in Honolulu. The R/V JOIDES Resolution arrived a full day early, having been scheduled in at 0700 h 5 May. The early arrival added a bonus day to a schedule that already was planned as a four-day port call.
The ship arrived with two propulsion motors out of service, requiring field coil replacement. This was the first priority activity upon arrival. The first day also included offloading of all refrigerated core samples and replacement of the logging winch transmission. During port call, vender representatives were aboard to replace the elevator mechanical interlocks with a solenoid actuated variety, balance the HVAC system, and repair and calibrate the Rigwatch rig instrumentation system (RIS). Normal on- and offloading activities took place, including loading of 10 short tons of attapulgite drilling mud left over from the Honolulu 1 port call, and 1537 metric tons of marine gas oil were bunkered. Training was conducted on the Rigwatch RIS and on operation of the Schlumberger logging line winch and wireline heave compensator systems. Other activities included a Det Norske Veritas International Safety Management audit of the ship and the arrival of Center for Deep Earth Exploration engineers to discuss the JOIDES Resolution's core winch regenerative braking system and coring tools.
Public relation activities were conducted dockside at the Pier 2B cruise ship terminal, the Waikiki Aquarium, and the Marriott Hotel Waikiki. Several high-level dignitaries and other management personnel, including the directors of the National Science Foundation, Ocean Leadership, the University of Hawaii, and Texas A&M University, were in attendance. Ship tours were conducted for dignitaries as well as University of Hawaii faculty and students and high school students and teachers.
The ship departed Honolulu with the last line away from Pier 2B at 0512 h. At ~10 nmi offshore the ship switched from cruise mode to dynamic positioning (DP) control and lowered thrusters. DP trials were conducted for 7 3/4 h to optimize system performance after changes in the ship profile were made during the Singapore refit. During this period a representative from L3, the Nautronics parent company, collected data and made adjustments to the internal windage modeling program that impacts the anticipatory commands of the system. The vendor was transferred from the JOIDES Resolution to the V/L Karake at the Honolulu Harbor outer sea buoy. At 1636 h the vessel got underway for Site U1336. Transit speed en route to the first site averaged 10.7 kt over the 79.0 nmi traversed by midnight on 9 May.
Transit to Site U1336 (proposed Site PEAT-5C) began at 1636 h on 9 May 2009. Transit to the first drill site continued with speed varying considerably as a result of fluctuating currents and eddies surrounding the Hawaiian Islands. Average transit speeds ranged from 9.9 to 10.7 kt with 135 turns on both shafts. One propulsion motor remained offline as field coil replacement continued. On the morning of 11 May, after several days of discussions with the science team, the decision was made to divert our course from Site U1336 to Site U1337 (proposed Site PEAT-7C). The decision was driven by several issues including (1) slower than anticipated transit speeds to date, (2) time spent conducting automated station keeping sea trials took longer than planned, (3) addition of VSI to the suite of wireline logging tools to be deployed at Site U1337, (4) basement projections deepened by 50 m because of results from Expedition 320, and (5) scientific trade-offs in general between completing Site U1336 more thoroughly versus doing a more complete program at Site U1338. During the transit, routine readiness inspections were conducted by the drill crew on all of the drilling equipment. During the inspection it was discovered that the passive heave compensator rod seals were burned up and required replacement. The ship arrived on location the morning of 19 May. The total 2320 nmi transit was accomplished in 9.8 days at an average speed of 10.0 kt.
Although the Global Positioning System (GPS) was the primary positioning reference used for this site, a new-generation acoustic beacon was also deployed at 1250 h on 19 May 2009. The automated station keeping system can be configured to accept position inputs from both the GPS and the seafloor acoustic beacon. Both inputs were used for Expedition 321.
Four holes were drilled at this site using the APC/XCB coring systems. One hole (U1337B) was terminated early when the XCB core barrel became stuck in the bit seal. This necessitated the drilling of the fourth hole. The cause of the stuck barrel was later identified as an errant APC shear pin stub. The first hole was successfully wireline logged using the triple combo, VSI, and FMS-sonic tool strings. Overall recovery for Site U1337, using both APC and XCB coring systems, was 96.0%. The basement contact was recovered in three of the four holes drilled at the site.
Rig floor operations commenced at 1200 h after the ship was stationary over the location coordinates. The pipe trip to the seafloor was slow because of the need for measuring (strapping) and drifting (internal diameter verification) of all tubulars and the picking up of the drill collars from the main deck storage rack. At 0300 h on 20 May, the top drive was picked up; however, the tilt/counter balance feature was not functional. Troubleshooting and repairing the top drive took 4 h before spacing out the drill string and deploying the first APC core barrel. With the bit positioned at 4467.0 m drilling depth below rig floor (DRF) the first APC barrel was pressured up and fired. Upon recovery, the leading edge of the APC cutting shoe was found severely damaged and the core barrel was empty. To confirm the approximate seafloor depth the drill string was lowered and the mudline was "tagged" twice at about the same depth of 4472.0 m DRF. This depth was taken as the official seafloor depth for the hole, the bit was repositioned 1.0 m lower at 4468.0 m DRF, and Hole U1337A was spudded at 1115 h. Core 321-U1337A-1H recovered 0.19 m of core, and once again the APC cutting shoe showed signs of having impacted something very hard. APC coring continued normally from there, however, and was suspended at 195.5 m DSF because of a 90 klb overpull. Nonmagnetic core barrels were used for all cores except Core 321-U1337A-21H. A 60 klb overpull for Core 321-U1337A-20H led to a return to steel core barrels. Average core recovery for the APC was 101.6%. FlexIt core orientation was conducted for all cores except Core 321-U1337A-1H with apparent good success. In addition, five successful APCT-3 temperature measurements were taken with Cores 321-U1337A-5H, 7H, 9H, 11H, and 13H at 43.5, 62.5, 81.5, 100.5, and 119.5 m DSF, respectively. Only one core liner split (Core 321-U1337A-8H), coincidently the first barrel shot with all three speed control holes open. XCB coring continued with Cores 321-U1337A-22X through 48X, achieving an average recovery of 87.1%. Two split core liners occurred during XCB coring (Cores 321-U1337A-37X and 38X). There was nothing significant noted in the coring parameters for these two cores other than the fact that Core 321-U1337A-38X achieved only 53% recovery compared to Core 321-U1337A-37X, which had 101% recovery. The sediment/basement contact was recovered at the base of Core 321-U1337A-48X. Total depth of Hole U1337A was 4921.8 m DRF (449.8 m DSF). Overall recovery for the hole using both APC and XCB coring systems was 93.4%. Rig-up for wireline logging began at 1130 h 23 May. Logging was successfully concluded and all logging equipment was rigged down by 0900 h on 25 May. Three logging strings were deployed. The triple combo reached total hole depth of 449.8 m DSF and obtained good-quality logs. The second logging string consisted of the VSI. This tool also reached total hole depth, and shooting stations were conducted at ~15 m stations. VSI logging was conducted during daylight hours to conform with established IODP mammal watch protocols, including a preshooting mammal watch and soft start procedures for the air guns. The third logging string (FMS-sonic) reached a depth of 440.0 m DSF (<10 m off bottom). With the end of pipe positioned at 82.6 m DSF, there were no reported issues with logging tools reentering the pipe. The drill string was pulled back until the bit cleared the seafloor at 0930 h on 25 May, ending operations in Hole U1337A.
The ship was offset 20 m west of Hole U1337A, and the bit was positioned at a depth of 4473.0 m DRF. This was to optimize the core break placement between the two holes, maximizing recovery of a complete section for the formation. The seafloor "tag" depth of 4472.0 m DRF for Hole U1337A was used for Hole U1337B. APC coring continued through Core 321-U1377B-27H to 245.2 m DSF. The FlexIt core orientation system was deployed successfully for all but two APC cores (321-U1377B-17H and 18H). Nonmagnetic core barrels were used through Core 321-U1377B-20H and successful APCT-3 temperature measurements were obtained with Cores 321-U1377B-15H, 17H, and 19H at 143.5, 162.5, and 181.5 m DSF, respectively. Overpull for the APC ranged from 20 to 90 klb and all but five barrels (Cores 321-U1377B-21H, 23H through 25H, and 27H) achieved full stroke. Two cores (321-U1377B-16H and 22H) were recovered with split liners. The first split occurred after recovery with the sectioned cores in the rack. The latter split occurred in the core barrel prior to extraction. Average core recovery for the APC was 99.3%. Coring continued with a single XCB core (321-U1377B-28X) to 251.9 m DSF; however, this barrel could not be recovered, forcing Hole U1337B to be abandoned prematurely. The drill string was recovered and further analysis indicated that an errant shear pin stub from an earlier piston core had caused the XCB core barrel to jam in the bit seal assembly. Operations in Hole U1337B officially ended at 2245 h on 27 May. Total depth achieved was 4723.9 m DRF (251.9 m DSF). Overall recovery for the hole using both APC and XCB coring systems was 96.6%. The lone XCB core (321-U1377B-28X) recovered nothing.
The ship was offset 20 m west from Hole U1337B and, the drill string was tripped to the seafloor. Hole U1337C was spudded with the bit positioned at 4471.0 m DRF. Recovery from APC Core 321-U1377C-1H established a seafloor depth of 4478.6 m DRF. Core 321-U1377C-2H extended the hole to a depth of 11.4 m DSF using nonmagnetic core barrels and the FlexIt core orientation system. A wash barrel was deployed, and the hole was washed to a depth of 169.4 m DSF. APC coring resumed at that depth and continued through Core 321-U1377C-9H to 221.3 m DSF. Steel core barrels were used at this point because of high overpull >70 klb. Full stroke was achieved with all cores except Core 321-U1377C-6H, which was advanced by recovery. Average core recovery for the APC was 102.6%. Coring with the XCB system continued with Cores 321-U1377C-10X through 33X, recovering 95.2% of the section. Total depth of the hole was 4918.9 m DRF (440.3 m DSF), and overall recovery, using both APC and XCB coring systems, was 97.0%. The drill string was pulled clear of the seafloor at 1400 h on 30 May, officially ending operations in Hole U1337C.
The plan for this hole was to duplicate recovery through those sections of the formation already recovered to provide additional sample material. In addition, the goal was to use a more focused coring approach to target once again the few remaining areas that had yet to be fully recovered. The most troublesome material was the large intervals of diatom mats and a porcellanite (baby chert) layer. Hole U1338D was spudded at 1645 h on 30 May. Recovery of APC Core 321-U1377D-1H placed the seafloor depth at 4476.5 m DRF. APC coring continued through Core 321-U1377D-26H to 237.7 m DSF. Nonmagnetic core barrels were used through Core 321-U1377D-20H and Core 321-U1377D-21H was shot with the bit 4.5 m off bottom to set up the first target area of interest. The first XCB core (321-U1377D-27X) was designed to only core through the hard ~0.5 m thick porcellanite (baby chert) layer but not into the material below. The APC was once again deployed, and Cores 321-U1377D-28H through 30H were cut to 267.0 m DSF. At this point the XCB coring system was once again deployed for Cores 321-U1377D-31X through 49X to a total depth of 442.9 m DSF. The FlexIt core orientation system was deployed successfully with all APC cores, and, with the exception of Core 321-U1377D-22H, all barrels fully stroked. Total recovery for the APC in this hole was 102.9%, and recovery with the XCB coring system was 89.6%. Total recovery for the hole was 97.5%. A much higher incidence of imploded or split liners plagued this hole, and we were unable to identify the reason. The drill string was recovered, the bottom-hole assembly was racked back in the derrick, and the rig floor was secured for transit. Once the bit cleared the seafloor the positioning beacon was recovered and thrusters and hydrophones were raised. At 1625 h on 2 June, control was switched from DP to cruise mode and the ship got underway for the next site.
The transit to Site U1338 (proposed Site PEAT-8D) began at 1625 h on 2 June 2009, after recovering all thrusters/hydrophones and shifting control to cruise mode on the bridge. The transit to the next site was uneventful, although initially the weather was somewhat dreary. Overcast skies and occasional rain was prevalent for most of the day. In relatively mild seas and moderate wind the vessel made good time, averaging 10.5 kt for the 324 nmi transit. Speed was reduced coming onto location. Thrusters and hydrophones were lowered and at 2320 h on 3 June, and control was switched from bridge cruise mode to DP.
As on the previous site, the position reference was a combination of GPS and an acoustic beacon on the seafloor. At 0005 h on 3 June, the same positioning beacon (FSI BAP-547, SN 1010, 15.0 kHz, 208 dB) used on the previous site was deployed. Four holes were drilled at this site using the APC/XCB coring systems. The last hole (U1338D) was limited to only three cores to be used in the labs for processing demonstrations during the upcoming expedition. Hole U1338B was wireline logged using the triple combo, FMS-sonic, and VSI tool strings. The APCT-3 temperature tool was deployed in Holes U1338A and U1338C. Overall recovery for Site U1338, using both APC and XCB coring systems, was 96.7%. Basement contact was recovered in two of the four holes drilled at the site.
Rig floor operations commenced at 2330 h. The top drive was picked up, and the drill string was spaced out, placing the bit at 4196.0 m DRF or 3.4 m above the "corrected" precision depth recorder depth of 4199.4 m DRF. The first APC barrel was pressured up and fired, but upon recovery it was discovered to have zero recovery (i.e., a "water" core). The bit was lowered an additional 5.0 m to 4201.0 m DRF, and another attempt for mudline was made. This time the barrel obviously contacted the mudline; however, the small amount of core recovered was completely destroyed by the sloshing of the water column above. For the third attempt, the bit was repositioned an additional 3.0 m lower at 4204.0 m DRF. This time the barrel recovered 2.7 m of core, and an official seafloor depth was established at 4210.8 m DRF. APC coring continued through Core 321-U1338A-24H to 221.2 m DSF using nonmagnetic coring assemblies and the FlexIt core orientation system. Overpull forces of 100 klb and the need to drillover the APC barrel led to the use of steel core barrels beginning with Core 321-U1338A-25H. APC coring was eventually ended with Core 321-U1338A-26H at 240.2 m DSF. All barrels fully stroked; however, the last three cores (321-U1338A-24H, 25H, and 26H) required 100 klb overpull and drillover to extract from the formation. Five successful APCT-3 temperature measurements were obtained with Cores 321-U1338A-5H, 7H, 9H, 11H, and 13H at 40.7, 59.7, 78.7, 97.7, and 116.7 m DSF, respectively. Average core recovery for the APC was 104.5%. XCB coring continued with Cores 321-U1338A-27X through 44X, achieving an average recovery of 55.9%. A small piece of basement was recovered in the core catcher of Core 321-U1338A-44X, defining total depth for Hole U1338A at 4620.8 m DRF (410.0 m DSF.) XCB coring performance was highly variable, with some cores achieving near 100% recovery and others recovering <1% and sometimes zero. In the areas of little or no recovery there were diatom-rich intervals and/or porcellanite (baby chert) found in the surrounding cores. Just as in the earlier holes at Site U1337, these proved to be the troublesome areas for recovery and were targeted in later Holes U1338B and U1338C in an attempt to complete recovery for the section. Overall recovery for Hole U1338A, using both APC and XCB coring systems, was 84.4%. The drill string was pulled clear of the seafloor at 1900 h on 6 June, officially ending operations in the hole.
Operations in Hole U1338B officially began when the drill string cleared the seafloor at 1900 h on 6 June. The drilling line was slipped and cut while the was offset ship 20 m to the west of Hole U1338A. With the drill bit placed at 4208.0 m DRF to optimize the core breaks between holes, the APC was deployed and once again a water core was recovered. After checking the drill string tally it was discovered that the driller was off by a single joint of drill pipe. This single was added to the string, and with the bit positioned at the same depth, the second hole for Site U1338 was spudded at 2330 h on 6 June. Core recovery with APC Core 321-U1338B-1H determined the seafloor depth as 4209.9 m DRF. Except for a short drilled interval of 2.5 m to adjust the core breaks, continuous APC coring continued through Core 321-U1338B-20H to 188.1 m DSF using the FlexIt core orientation system and nonmagnetic coring assemblies. FlexIt and steel core barrels were then used as APC coring continued through Core 321-U1338B-42H to 387.4 m DSF. Hole U1338B is the second deepest APC hole in ODP and IODP history, surpassing the 378.0 m DSF depth achieved during Expedition 320 in Hole U1335B. APC extraction overpull reached 100 klb on 19 of the 42 cores taken, including the last 11 cores. Full stroke was achieved on all but two cores (321-U1338B-30H and 31H) through the interval from 276.1 to 282.9 m DSF. Coincidentally, the shear pressure for these two cores was inconclusive, so this may have been the reason for the incomplete stroke. Drillover was required on 13 cores, including the last ten. Except for Cores 321-U1338B-30H and 31H, shear pressures were consistent throughout the coring process at 2800 psi. Core liner issues were relatively mild. The Core 321-U1338B-1H liner was broken, the liner for Core 321-U1338B-13H was cracked at the bottom, and the liner in Core 321-U1338B-42H was recovered split. Average core recovery for the APC was 104.1%. Coring continued with three XCB cores (321-U1338B-43X through 45X) to 416.1 m DSF. Basement contact was recovered in Core 321-U1338B-45X. Overall the XCB coring system recovered 57.9% of the interval penetrated. Recovery was problematic with the XCB, and the material that was recovered suffered significantly from the typical "biscuiting" effect. Total depth of Hole U1338B was 4626.0 m DRF (416.1 m DSF). Overall core recovery using both APC and XCB coring systems was 100.9%. The hole was swept clean with 50 bbl of attapulgite mud. A wiper trip revealed no ledges or bridges, and no fill was identified at total depth. The lockable float valve was locked open, the hole was displaced with heavy 10.5 ppg logging mud, and the end of pipe was placed at 84.7 m DSF. Rig-up for wireline logging began at 2145 h on 9 June. Wireline logging in Hole U1338B was successfully concluded and all logging equipment was rigged down by 1615 h on 11 June. Three logging strings were deployed. The triple combo and the FMS-sonic tool reached total hole depth of 416.1 m DSF. The third and final logging string consisted of the VSI. This tool reached total hole depth and shooting stations were conducted at ~15 m stations. All logging was done during daylight hours to conform with established IODP mammal watch protocols, including a preshooting mammal watch and soft start procedures for the air guns. The drill string was pulled back until the bit cleared the seafloor at 1655 h on 11 June, officially ending operations in Hole U1338B.
Operations in Hole U1338C officially began when the drill string cleared the seafloor at 1655 h on 11 June. The ship was offset 20 m to the west of Hole U1338B. The drilling line was slipped and cut and the Rigwatch drawworks/block position encoder was recalibrated. The drill bit was placed at 4204 m DRF (same as Hole U1338A) to optimize the core breaks between Holes U1338A and U1338B. The APC was deployed, and, for the third time at this site, a water core was recovered. Because 2.7 m of core had been recovered in Hole U1338A with the same bit placement, it was suspected that vessel heave, induced by the large long-period swell train from the south, had impacted bit placement by being on the high side of the swell displacement. The drill string was lowered another 3 m, and the bit was repositioned at 4207.0 m DRF. Hole U1338C was spudded at 2135 h on 11 June. The 3.83 m of core recovery with APC Core 321-U1338C-1H determined the seafloor depth at 4212.7 m DRF. APC coring continued through Core 321-U1338C-21H to 189.8 m DSF using the FlexIt core orientation system and nonmagnetic coring assemblies. FlexIt and steel core barrels were then used as APC coring continued through Core 321-U1338C-44H to 396.9 m DSF. Conditions indicated that Core 321-U1338C-45H fully stroked, and drillover was required to extract it from the formation. Retrieval was delayed because a bent core barrel initially prohibited entry into the drill string. Repeated jarring with the wireline jars eventually sheared the overshot pin. The sinker bar string was recovered, and the FlexIt core orientation tool was removed. The sinker bar assembly was redeployed, and the core barrel was immediately recovered without any further incident. It was deemed prudent at this point to leave the FlexIt tool out of the assembly for the remainder of the coring process. Coring continued through Core 321-U1338C-47H to a total depth of 414.4 m DSF, setting a new all time depth record for the APC. This surpassed the standing ODP record set on 7 August 1992 (Leg 145) when the APC recovered 42 piston cores to a total depth of 398.3 m DSF in Hole 882A. APC extraction overpull reached 100 klb on Cores 321-U1338C-22H through 47H. Drillover prior to removal from the formation was required for 22 cores and full stroke was achieved on all but four cores (321-U1338C-31H and 45H through 47H). Shear pressures were consistent throughout the coring process at 2800 psi. Core liner issues were relatively mild with only two cores recovered with imploded liners (Cores 321-U1338C-10H and 12H), although several barrels were bent during the coring process and several piston rods had to be adjusted and repinned because of overtorqued threads that caused miss-alignment of the rod grooves. Overall core recovery for the APC was 104.4%. The drill string was pulled clear of the seafloor at 2015 h on 14 June, officially ending operations in Hole U1338C.
Operations in Hole U1338D officially began when the drill string cleared the seafloor at 2015 h on 14 June. The ship was offset 20 m to the west of Hole U1338C. This hole was primarily planned to recover a few "instructional" cores for lab demonstrations to be used during Expedition 323. Hole U1338D was spudded at 2150 h on 14 June, and the 4.89 m recovered with Core 321-U1338D-1H established a seafloor depth of 4212.6 m DSF. Three APC cores were cut to 23.9 m DSF. APC core recovery was 103.7%. Official APC/XCB coring totals for Site U1338 include 139 total cores, 1261.9 m penetrated, and 1220.41 m recovered, for 96.7% recovery. The coring tools were secured and the drill string was pulled clear of the seafloor at 0145 h on 15 June. The top drive was set back, the knobby joints were laid out, and the drill string was recovered. Once the drill collars were laid out and the rig floor was secured for transit, control was transferred from DP to the bridge. The ship was placed in cruise mode at 1030 h on 15 for the anticipated 7.6 day (1811 nmi) transit to San Diego.
The vessel departed Site U1338 ~4 1/2 hours ahead of the projected schedule on a northerly course. The 1811 nmi transit from Site U1338 to the San Diego pilot station required 7.3 days at an average speed of 10.5 kt. Expedition 321, the second and final segment of the PEAT program, was officially concluded at 1715 h on 22 June with the first line ashore Berth 10-7 at the Tenth Avenue Marine Terminal, San Diego Harbor.