Leg 209 began at 0956 hr on 6 May 2003 as the first line ashore at Berth 3, Porto Praca Maua, Rio de Janeiro, Brazil, ended Leg 208. Pacing items for the port call included resupply of fuel and drill mud bulk, loading casing scheduled for deployment during Leg 210, and installation of a remote diagnostic system for the active heave compensator (AHC). A complete overhaul and test of the drawworks transmission was also completed during the port call.
Two power outages traced to a faulty transformer occurred on the JOIDES Resolution early on the morning of 10 May. Repairing the transformer ultimately became the primary port call pacing item and resulted in a 1-day delay in our scheduled departure. After rotating the ship 180° to load a new spool of drilling cable on the starboard side, mooring lines were released and the last line was brought aboard at 0912 hr on 12 May. The pilot departed at 0954 hr, and the vessel got under way at full speed for the 2627-nmi transit to our first site.
Transit speed over our first 4 days at sea averaged 11.3 kt. During the transit an air sampling system for airborne microbial study was modified and mounted at the water table level of the derrick.
At 0925 hr on 15 May, the ship's master was informed that the Overseas Drilling Ltd. Electrical Supervisor required medical evacuation. At 0946 hr we changed course to 328° and steamed toward the port of Aracaju, Brazil, 109 nmi away. At 1654 hr we arrived at our rendezvous location (11°18'S, 36°45'W) and proceeded at reduced speed until arrival of a medivac helicopter. Brazilian police helicopter PT-HVA was on board by 1726 hr and departed at 1731 hr. We immediately resumed full speed, changed course to 055°, and proceeded up the eastern coast of Brazil. Overall impact to the leg for the medivac operation was an additional ~60 nmi steaming, or ~5 hr.
During the next 6 days of our transit we averaged 11.7 kt, until a wind heading change and the Equatorial Counter Current slowed our speed. We arrived at Site 1268 at 0500 hr the morning of 22 May. Our transit totaled 2680 nmi at an average speed of 11.4 kt.
The planned location of Site 1268 was revised during transit from Rio de Janeiro after detailed review of the video tapes from Shinkai 6500 Dive 427 in 1998. The site was to be in thin sediments at ~3011 meters below sea level (mbsl), overlying a flat, planar outcrop of serpentinized peridotite (probably a fault surface) visible a few meters downslope. Upon arrival at the planned location, the precision depth recorder (PDR) in the underway geophysics laboratory indicated a depth of ~2896 meters below rig floor (mbrf) (2885 mbsl), quite different from the expected depth. Given that submersible dive navigation can be uncertain, we undertook a PDR survey of the seafloor to the southeast (downslope). While making up the drilling assembly, the first 8-1/4-in drill collar, the rig crew discovered a significant crack in the stress relief groove of the pin thread. This collar was laid aside and we decided to magnaflux inspect the remaining eight drill collars in the bottom-hole assembly (BHA). No other cracks were found during the inspection.
While running the drill pipe, we chose a position ~600 m southeast of the originally planned location, with a PDR depth of ~3040 mbsl, to start a camera survey. However, when the camera depth was at ~3080 m, the sonar on the camera sled still could not detect bottom within 100 m. At this point, the ship began moving slowly northwest toward the originally planned site location. Bottom was first detected at ~3180 mbsl at a position ~500 m southeast of the originally planned location. Bathymetry determined during the camera survey conformed closely to bathymetry based on Shinkai 6500 Dive 427 at the same latitude and longitude, so we decided that the PDR depths were probably incorrect. At this point, the drill string and camera sled were raised to a bit depth of ~3008 m and the originally planned location for Site 1268 was slowly approached. Again, bathymetry determined from the camera survey at the originally planned location conformed closely to that observed on Shinkai 6500 Dive 427, confirming the theory that dive navigation in this case was accurate and PDR depths were incorrect. The close equivalence between camera survey and dive bathymetry indicated that we were very near the originally planned location. Push tests indicated that sediment thickness was ~4 m, slightly thicker than anticipated but within acceptable limits. The positioning beacon was released from the vibration-isolated television (VIT) frame ~20 m away from the identified spud location prior to recovering the VIT.
Before initiating coring we deployed the Water Sampling Temperature Probe (WSTP) to obtain a temperature and a seawater sample for a microbiology contamination baseline analysis. Hole 1268A was spudded at 0620 hr on 23 May (Table T1). After cutting Core 209-1268A-1R the AHC was turned off because of erratic performance. The supporting data were recorded both in the newly installed Maritime Hydraulics (MH) diagnostic computer and the Texas A&M University (TAMU) TruVu rig instrumentation system. TruVu was running in the 1-s capture mode. MH-Norway accessed their diagnostic computer remotely and downloaded the data for analysis. Initial reports indicated a possible problem with the AHC motion reference unit (MRU).
Core 209-1268A-1R advanced to 14.0 meters below seafloor, allowing the bit to stay in the hole during the next connection. A standard rotary core barrel (RCB) core barrel was used without a core liner. All subsequent cores were taken using nonmagnetic chrome-plated inner diameter (ID) core barrels. In order to improve recovery, we opted to retrieve cores nominally every 5 m (half cores).
Sepiolite mud sweeps (10 bbl) were circulated every 10 m, and the hole remained stable through Core 209-1268A-28R at 145.1 mbsf with no fill or overpull during connections. After making a connection prior to cutting Core 209-1268A-29R, the driller noted elevated torque and ~1.0 m of fill in the bottom of the hole. After pumping a pair of 20-bbl sepiolite mud sweeps, all drilling parameters returned to normal. While cutting Core 209-1268A- 29R, drilling parameters indicated the hole had collapsed, stalling the top drive and preventing any further rotation or axial movement of the drill string. After an unsuccessful attempt to free the pipe, we decided to sever the drill string above the BHA. The mate to the severed joint cleared the rig floor at 1930 hr, ending Hole 1269A and drilling operations at Site 1268. The average rate of penetration (ROP) for the hole was 3.9 m/hr.
Using the ship's dynamic positioning system, we moved ~5 nmi to Site 1269. During the move a two-stand BHA was built consisting of six 8.25-in drill collars. This was done to minimize the risk of losing additional drill collars and jeopardizing further operations. As at Site 1268, all collars were inspected before inclusion in the drill string.
Prior to initiating Hole 1269A, we undertook a 1.25 hr subsea camera survey to verify our location as compared to site survey video tapes. The drilling target for Site 1269 was along the track of Shinkai 6500 submersible Dive 423 in 1998, which recovered samples of peridotite and gabbro from a series of steep outcrops separated by flat, sedimented seafloor along the western flank of the Mid-Atlantic Ridge axial valley. Our camera survey for Hole 1269A began at a depth where the site survey dive had recovered dunite (Shinkai 6500 Dive 423, sample R007). After moving downslope 60 m to ensure we were above an outcrop and in sediment free of talus, we released a positioning beacon from the camera frame 30 m east of our selected drilling target, retrieved the camera, and spudded Hole 1269A.
Hole 1269A was initiated at 1005 hr on 27 May with a seafloor tag depth of 2800 mbsl. Coring continued to a depth of 15.3 mbsf before high drilling torque, collapsing hole, and low recovery (2.6%) consisting of only fragments of basalt led us to terminate coring. At 1425 hr 27 May the bit cleared the seafloor, ending Hole 1269A.
Our second subsea camera survey at Site 1269 began with the drill pipe over the positioning beacon. We surveyed 60 m west, continuing along a flat sedimented seafloor, free of talus shed from uphill. A push-in test indicated the sediment was <5 m thick, so we retrieved the camera and spudded Hole 1269B.
At 1950 hr on 27 May, Hole 1269B was initiated with a seafloor tag depth of 2799 mbsl. The first core was recovered after 11.1 m penetration and again contained only a few pieces of basalt. As at Hole 1269A, high torque and recovery of only basalt fragments suggested we would not reach our drilling objectives without first drilling through an unknown thickness of unstable basaltic lava, so we abandoned the hole. The bit cleared the seafloor at 2215 hr on 27 May, ending Hole 1269B. Anticipating a move of ~1 km, we recovered the positioning beacon.
With two holes at our most promising target yielding only basalt, we elected to move farther uphill (west) for our next hole at Site 1269. After offsetting the drill ship ~1.1 km west, we conducted our third subsea camera survey at this site. This location was near the top of the western rift valley wall, in a flat, sedimented terrain above a moderate slope from which four samples of gabbro were collected during Shinkai 6500 Dive 423. After surveying 275 m upslope, we returned to a position ~65 m west of the start of our camera survey to begin Hole 1269C.
Hole 1269C was initiated at 1118 hr on 28 May. Coring was again hampered by high and erratic torque, and the two core barrels (to a depth of 18.3 mbsf) that were recovered contained only a few fragments of basalt. Recognizing that our favored drilling targets at Site 1269 were all covered with a basaltic carapace beneath a few meters of pelagic sediment, we elected to terminate coring at this site and to move to one of our alternate sites. The drill string and positioning beacon were recovered and we completed operations at Site 1269 at 2000 hr on 28 May.
Site 1270 is the southernmost of all sites occupied during Leg 209, 16 nmi southeast of Site 1269. Originally planned as an alternate site, this location is on the ridge flank at the eastern limit of the axial valley. The site survey dive tapes reveal an exposed fault surface, and samples of mylonitic peridotite were recovered during the dive. We chose to occupy this site as a result of poor hole conditions and low recovery, including only basalt, at Site 1270.
On 28 May, we arrived at the Global Positioning System (GPS) coordinates of a position along the dive track of Shinkai 6500 Dive 425 just upslope of where serpentinized peridotite had been sampled from a large outcrop (sample R007). A six-collar BHA (nominally 130 m long) was lowered with the drill string, and the subsea camera was deployed. After a ~3.5-hr survey, where we recognized several intervals of bare rock exposure, we selected a drilling target ~150 m west of our camera survey starting position.
Hole 1270A was initiated with slow rotation and low bit weight at 0500 hr on 29 May. The upper guide horn was removed to allow us to keep the subsea camera near the seafloor as we started the hole, to ensure the bit did not track down slope. After 3 m of penetration, the camera was retrieved and coring continued through Core 209-1270A-4R (0.026.9 mbsf). Core 4R contained fault gouge, and our attempt to deepen the hole was hampered by erratic torque on the drill string and wall collapse, filling the borehole. After hole cleaning attempts failed, we pulled clear of the seafloor at 1600 hr on 29 May, ending Hole 1270A.
We returned to our original camera survey position, redeployed the subsea camera, and began a survey upslope in search of a new drilling location on a bare rock exposure. We moved 100 m east along an azimuth of ~120° over the path followed by Shinkai 6500 Dive 425, then turned south to follow a depth contour where outcrop was evident in the dive video tape. After completing a rectangular box survey pattern, we located an extensive exposure of bare rock ~230 m southeast of Hole 1270A and initiated Hole 1270B.
Coring began at Hole 1270B as at Hole 1270A (at 0200 hr on 30 May) by advancing the bit with slow rotation and low bit weight to 3 mbsf while observing the operation with the subsea camera. After retrieving the camera, we cored to a depth of 45.9 mbsf (Cores 209-1270B-1R to 10M). As we began our third coring interval, the bit would not advance past 13.5 mbsf (1 m deeper than the top of Core 209-1270B-2R). At that depth, coring continued as if we had not already drilled the interval between 13.5 and 17.4 mbsf. Core 209-1270B-3M represents rock recovered in generally same interval as Core 209-1270B-2R (13.517.4 mbsf) but contains >1 m of cut core cylinders. When the same blockage was encountered at virtually the same depth on our next coring attempt (13.5 mbsf) we cored beyond the bottom depth of Core 209-1270B-2R and 3M, to 22 mbsf. Since we redrilled the upper part of the interval, the recovered core was curated as Core 209-1270B-4M. Normal coring curation and nomenclature was resumed with Core 209-1270B-5R, when we were sure we were coring a new interval from the beginning of the cored interval. Coring progressed steadily with improving recovery until Core 209-1270B-9R. Hard fill in the bottom of the hole prevented advancement and caused high and erratic torque. Since we were still operating with a reduced-length BHA, we chose not to risk getting the pipe stuck and abandoned the hole at 1205 hr on 31 May.
We began our third camera survey at the GPS coordinates of sample R008 from Shinkai 6500 Dive 425 where mylonitinized peridotite had been sampled. Unlike outcrops at our two previous holes (bare rock free of talus), the dive video tape revealed this outcrop was littered with what appeared to be slabs of rock, albeit more or less in place. We selected this location upslope from our two previous holes, surmising that if the fault gouge encountered at depth in Hole1270A was a result of incipient landsliding, this older, more weathered outcrop might yield better drilling conditions. After a 2.5-hr survey, we selected a drilling target ~240 m east of Hole 1270B.
Hole 1270C was initiated at 1735 hr on 31 May in a similar manner as for our two previous holes. Coring only progressed to 18.5 mbsf (Cores 209-1270C-1R and 2R) before the hole began to fill, restricting circulation. No advancement was possible on our third coring interval even after 2.5 hr of rotation, so the core barrel was recovered (curated as Core 209-1270C-3M) and the hole was abandoned at 0300 hr on 1 June.
The survey for Hole 1270D began over the position of Hole 1270C. We moved only a short distance (~30 m east) and selected a drilling target in bare rock. At 0730 hr on 1 May, Hole 1270D was initiated while we watched the operation with the subsea camera. We cored to 3 mbsf before the camera cable appeared to start wrapping around the drill string. While recovering the camera (without rotating the pipe) the driller became concerned when he was required to advance the pipe to maintain a minimum weight on bit. Upon lowering the camera back to the seafloor, the camera image showed that the bit had slid off the outcrop and embedded in sediment. A second hole initiation (at 0934 on 1 June) was successful to 3 mbsf, so the camera was retrieved and coring continued to 57.3 mbsf. After recovering Core 209-1270D-11R, hole conditions deteriorated to the point that no further advance was possible. The bit was pulled clear of the seafloor, ending operations at Site 1270 at 1445 hr on 2 June. ROP at Site 1270 varied from 3 to 7 m/hr.
Site 1271 is on the southern end of the inside corner high south of the 15°20'N Fracture Zone, ~19 nmi northwest of Site 1270. We again chose to use a six-collar BHA in order to ensure the preservation of sufficient BHA components for future drilling during this leg.
Our camera survey for Hole 1271A began at GPS coordinates between samples of gabbro and peridotite collected during Faranaut Dive 7. Our target was a smooth, sedimented slope above an outcrop of gabbro. After a 1.75-hr survey, we confirmed our location was on a shallow, eastward-dipping slope of smooth sediment, and our depth (estimated from drill string length) was consistent with our desired drilling location.
Hole 1271A was initiated at 0545 hr on 3 June through 2.5 m of sediment above a peridotite outcrop. The first core required 4.75 hr to advance to 12.9 mbsf. Cores 209-1271A-2R and 3R, however, cored in at total of 50 min. After recovering Core 209-1271A-5R, hole conditions began to deteriorate and the driller noted the hole had begun to fill between connections. After only advancing 2.0 m on Core 209-1271A-6R, we decided to abandon any further attempt to core deeper. The bit was pulled clear of the seafloor at 0244 hr, ending Hole 1271A. The average ROP for the hole was 4.5 m/hr.
Since the shallow sedimented slope where we located Hole 1271A seemed to be our most promising drilling target (based on Faranaut Dive 7 video tapes), we decided to move southwest along the same depth contour to position Hole 1271B. Hole 1271B was spudded ~90 m from Hole 1271A.
At 0730 hr on 4 June we began coring Hole 1271B. Cores 209-1271B-1R to 3R were cored without incident, but while drilling Core 4R the driller suspected that a piece of rock had lodged in the bit throat or the bottom of the core barrel. High circulating pressure eventually cleared the obstruction. After cutting Core 209-1271B-4R, the driller had difficulty getting the pipe back to the bottom of the hole through several meters of hard fill.
Coring continued through Core 209-1271B-20R (103.8 mbsf) with low recovery but little or no indication of poor hole conditions. Having achieved a depth >100 mbsf, we chose to curtail coring operations in order to collect wireline logging data. Coring was completed by 1345 hr on 6 June, and the bit was released in the bottom of Hole 1271B. As the driller attempted to pull the bottom of the pipe to logging depth (nominally 30 mbsf), the hole appeared to collapse around the pipe, shutting off circulation. With some difficulty, the pipe was freed and circulation regained.
After securing the pipe at 30 mbsf, the first logging tool was set up and run into the hole. However, the logging tool would not advance more than 6 m past the end of the pipe, indicating catastrophic hole collapse. Our logging attempt was regretfully abandoned. After the pipe was raised to 2300 mbsl, we recovered the positioning beacons and began the short transit (~3.7 nmi) to our next site. Operations at Site 1271 ended at 0745 hr on 7 June. The average ROP for the hole was 4.0 m/hr.
Site 1272 is the northernmost of our drilling locations on the transect of sites south of the 15°20'N Fracture Zone, on the northwestern flank of the inside corner high. The site was targeted based on reviews of video tapes from Faranaut Dives 5 and 2, near the top of the ridge where most of the dive samples were serpentinized peridotite. Site 1272 is ~3.7 nmi north of Site 1271.
Having protected our supply of drill collars during earlier operations, we elected to increase the length of our BHA at this site in order to achieve deeper penetration without placing the top of the BHA below the seafloor. A total of 14 8.25-in drill collars (nominally 131 m long) were lowered at the end of the drill string while we positioned the vessel over the GPS coordinates of our camera survey starting position. We surveyed along a shallow-dipping, sediment-covered slope and selected a drilling target located in flat terrain between the depths of Faranaut Dive 2 samples FR02-11 and FR-02-12 (both serpentinized peridotite). A push-in test with the drill string indicated the sediment cover was only ~1 m thick.
Hole 1272A was spudded at 2045 hr on 7 June. Core 209-1272A-1R advanced to 12.9 mbsf. Coring continued through Core 209-1272A-27R to a depth of 131.0 mbsf with no difficulty but slow penetration (average ROP = 2.2 m/hr). Because the core we were recovering was clay rich and we encountered several intervals of drilling-induced disturbance, we elected to use core liners inside the core barrels to see if recovery might improve. Core liners were used on Cores 209-1272A-21R and 23R through 27R, and recovery improved to values as high as 79% (averaging = ~55% as compared to ~30% recovery in similar lithology cored without liners).
The Drill String Accelerometer (DSA) tool was deployed with Cores 209-1272A-12R and 14R. After coring to 131 mbsf with little change in the character of the recovered core or in drilling conditions, we decided to terminate coring and begin wireline logging.
Two logging tool strings were deployed in the hole. Both the triple combination (triple combo) and Formation MicroScanner (FMS)-sonic tool strings reached within 67 m of the bottom of the hole. With logging completed, the pipe was pulled clear of the seafloor at 0245 hr on 12 May. By 0730 hr the ship was secured for transit, ending operations at Site 1272.
Site 1273 is the southernmost drilling target on our transect of sites north of the 15°20'N Fracture Zone. This site was selected based on review of video tapes from Faranaut Dive 16, which recovered samples of peridotite and gabbro.
At 1716 hr on 12 June we arrived at the coordinates for the Site 1273 camera survey. While we deployed a BHA including 17 8.25-in drill collars (nominally 159 m long) at the end of the drill string, the subsea camera was lowered along with a positioning beacon. Our camera survey track was from west to east starting on a flat, sedimented terrace, moving downslope until we arrived at the edge of a precipitous cliff. During Faranaut Dive 16, the submarine traversed upslope >100 m in <5 min until the seafloor slope sharply decreased at the same water depth as our camera survey. Outcrop was exposed along all of this part of the dive track, and a sample of serpentinized peridotite was collected. Inferring that we were near the same outcrop recorded on the dive survey video tapes, we moved 50 m back up the shallow slope to deploy the beacon, and at 0515 hr on 13 June we initiated Hole 1273A ~30 m west of the cliff edge.
Only one core was recovered from Hole 1273A before we were forced to abandon coring because of borehole wall collapse. Hole 1273A ended at 0920 hr on 13 June as the bit was pulled free of the seafloor.
Hole 1273B was spudded at 1050 hr on 13 June, after offsetting the ship ~15 m east (closer to the cliff edge). Cores 209-1273B-2R to 3R penetrated quickly (11.626.2 mbsf in <2 hr), and, as at Hole 1273A, the driller could not keep the hole cleared of debris. Hole 1273B was completed by 1900 hr on June 13 as the bit was pulled free of the seafloor.
Because our site survey bathymetry data indicated the flat terrace where we drilled Holes 1273A and 1273B continued south for at least 500 m, we began a second subsea camera survey tracking south along the top of the cliff. After moving ~100 m while crossing back and forth across the cliff edge, we located a massive outcrop that we considered an ideal target for coring. At 0100 hr on 14 June we spudded Hole 1273C a few meters west of the cliff in sediment <2 m thick. Core 209-1273C-1R was advanced to 18 mbsf because material collapsing into the hole prevented us from setting the pipe to extract the core barrel. Cores 209-1273C-2R and 3R were difficult to core, as material seemed to be falling into the hole as soon as we stopped coring to make a pipe connection. After recovering Core 209-1273C-3R, the drill pipe would not pass 20 mbsf, indicating 8 m of material had fallen into the bottom of the hole. Given that recovery in all three holes was limited to small fragments of basalt with only two small pieces of peridotite, we chose to end coring attempts at Site 1273.
After a transit from Site 1273 in dynamic positioning mode with the drill string suspended below the ship, we arrived on the GPS position coordinates for the start of the Hole 1274A subsea camera survey at 0030 hr on 15 June.
Our survey began over a sedimented bottom and tracked ~200 m west, up the side of the western wall of the axial valley of the Mid-Atlantic Ridge, following the path of Shinkai 6500 Dive 416. During this dive all recovered samples were serpentinized peridotite. After passing an outcrop at the depth of the final sample of peridotite collected during the dive, we selected a drilling target with a thin sediment cover (<2 m) to initiate Hole 1274A.
Before beginning our coring operation, we deployed the WSTP to collect a bottom water sample in support of our microbiology program. Coring continued through 155.8 mbsf (Cores 209-1274A-1R to 28R) with little difficulty. The only problems of note were an easily cleared bit blockage experienced after recovering Core 209-1274A-11R and minor amounts of fill collapsing into the hole between pipe connections. Cores 209-1274A-15R, 20R, and 21R were cut as full ~9.6-m intervals (as opposed to the nominal half cores that we recovered throughout the rest of the hole) because of rapid penetration through those depths (74.083.7 and 102.9122.1mbsf, respectively). After we recovered Core 209-1274A-28R, the hole collapsed and cut off circulation through the drill string. Pipe was pulled from the hole while attempting to restore circulation, without success, so we released the bit and abandoned Hole 1274A. The average ROP for Hole 1274A was 4.9 m/hr.
After a brief ~10-nmi transit west from Site 1274, we arrived at Site 1275.
At 0445 hr on 19 June, we began a camera survey on the top of a large dome, surveyed by the 1998 Shinkai 6500 Dive 422. During that dive, gabbro and peridotite were recovered from the southern flank of the dome. Our first drilling target was smooth, slabby outcrops on the north end of the dome summit.
Our camera survey for Hole 1275A required <2 hr, and we selected a target on a bare rock outcrop. We initiated coring at 0815 hr at a water depth of 1563 mbsf. In an attempt to recover the uppermost surface of the outcrop, we elected to recover the core barrel after only 5 m of penetration. Because we had to lift the pipe above seafloor in order to have the proper pipe spacing at the rig floor to extract the core barrel, Core 209-1275A-1R was the only core recovered from this hole.
In an attempt to remain on or at least very near the outcrop where we cored Hole 1275A, we moved 4 m south in dynamic positioning mode to begin Hole 1275B. Core 209-1275B-1R was cored to a depth of 11.0 mbsf and required >10 hr to drill. Coring continued through Core 209-1275B-22R (108.7 mbsf). Because our rate of penetration early in the hole was so low and the bit had been used for nearly 80 hr of coring, we chose to terminate coring to attempt logging while coring (LWC) at a nearby location. We did not release the bit in the bottom of the hole, so we would have the option to attempt a bare hole reentry, then deepen and log Hole 1275B if time allowed. The location of Hole 1275B was marked with a glass float deployed from the subsea camera frame prior to abandonment. The average ROP for the hole was only 1.4 m/hr.
Our target for the LWC operation was, in our estimation, the most optimum location for high recovery occupied during Leg 209. We selected a drilling location at the site of an outcrop where the precruise dive survey had collected serpentinized plagioclase-bearing peridotite. This site was ~90 m south of Holes 1275A and 1275B. Relatively high recovery in hard rock from nearby Hole 1275B (>43%), combined with shallow water and calm seas, should have made for ideal deployment conditions. We deployed a standard eight-collar BHA, as memory on the LWC tool (resistivity at the bit with coring [RAB-C]) is only 70 rotating hr in its current configuration, and we did not expect to penetrate more than ~70 mbsf in that time.
After conducting a brief (1 hr) subsea camera survey, we located an outcrop near the coordinates where peridotite was sampled during the Shinkai 6500 dive. Hole 1275C was initiated at 0445 hr on 24 June, with the same slow penetration rate we experienced in Hole 1275B. However, after three cores and nearly 20 hr of operations we had reached only 20.8 mbsf and the three core barrels we recovered were either empty (Core 209-1275C-1R) or contained only one or two small rounded cobbles of rock. Compared to recovery on initial cores from all our previous drilling locations, recovery with the RAB-C was significantly poorer than with our convention rotary system (see Fig. 60). Based on poor recovery, we abandoned Hole 1270C.
In an attempt to ensure the deepest penetration possible in the time we had left, we deployed a 22-collar BHA in preparation for coring Hole 1275D. We offset 4 m west from Hole 1275C and began coring Hole 1275D at 1025 hr on 25 June. Coring in the same interval at the RAB-C (Cores 209-1275D-1R to 3R; 017.6 mbsf) yielded 32% recovery. This was the highest rate of recovery from the first three cores from any hole drilled during Leg 209. Coring continued through Core 209-1275D-43R (209 mbsf), averaging >50% recovery. We terminated coring at 0915 hr on 30 June in order to leave time for wireline logging. The average ROP for Hole 1275D was 2.4 m/hr. Wireline logging failed to pass an obstruction at ~103 mbsf, but two tool strings (triple combo and FMS-sonic) were deployed over the interval 10320 mbsf. The pipe was pulled clear of the seafloor at 0515 hr on July 1, ending operations for Leg 209, and after recovering the pipe, we began our transit to Bermuda.
The highlight of the transit was a sampling party for shipboard scientists' postcruise research Nearly 400 sections of core (the complete volume of >350 m of core recovered during Leg 209) were arranged throughout the upper two floors of the lab stack.
The 1410-nmi transit was completed at an average speed of 11.6 kt. Leg 209 ended with the first line ashore at Market Wharf, St. George, Bermuda, at 1715 hr on 6 July 2003.
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