IODP Expedition 401
Mediterranean–Atlantic Gateway Exchange
Daily science report for 31 December 2023
Location: Hole U1610A (36°41.9812′N, 7°25.8844′W; water depth 556.3 mbsl [updated])
Science Update: The rig floor team continued to raise the mud motor BHA back to the ship and disassemble it. The upper guide horn was moved back into place, and the XCB BHA was assembled with a PDC bit. We elected to start coring in Hole U1610A with the XCB system because it had recovered good quality cores at equivalent depths in Hole U1609A. We anticipate that we will have to change to the rotary core barrel (RCB) system at some depth in Hole U1610A, but the extra time taken to exchange BHAs will be outweighed by the good quality of the XCB cores. The bit was lowered close to the seafloor and the subsea camera was deployed to guide reentry. Hole U1610A was reentered at 0940 h, and during this process the depth to seafloor was found to be 556.3 mbsl, which is a more accurate determination than the previous estimate of 561.7 mbsl. The camera was raised back to the ship by 1030 h, and the bit was lowered to the base of the hole, 505.2 mbsf. The hole was swept with 30 bbl of sepiolite mud, and at 1315 h the first science activity was to run the SET2 tool. At 1430 h we started coring. Cores U1610A-2X to 4X penetrated from 505.2 to 538.5 mbsf and recovered 30.8 m (93%).
The science party laboratory teams finished writing their sections for the Site U1609 chapter, and they started analyzing cores from Hole U1610A. Core U1610A-2X consists of calcareous mud and calcareous silty mud. At midnight, scientists, technical staff, and crew members met on the bow to ring in the new year.
Daily science report for 30 December 2023
Location: Hole U1610A (36°41.9812′N, 7°25.8844′W; water depth 561.7 mbsl)
Science Update: We continued to drill in the 10.75 inch casing, pumping five 30 bbl sepiolite mud sweeps to flush out sediment and keep the hole clear. At 1700 h, when the bit reached 480 mbsf, the subsea camera was deployed to observe the funnel’s approach to the seafloor. The base landed on the seafloor with the bit at a depth of ~506 mbsf. The HRT go-devil was dropped down the pipe to release the pipe and BHA from the casing system; after the release had been verified, the subsea camera was raised back to the ship. The bit was raised, clearing seafloor at 2215 h and continuing to raise for the rest of the day.
The science party met to continue to refine the lithostratigraphy and dating of Site U1609 and to write up the results for the site chapter. They were given a presentation to preview coring at Site U1610, including seismic surveys and previous coring in the area.
Daily science report for 29 December 2023
Location: Hole U1610A (36°41.9812′N, 7°25.8844′W; water depth 561.7 mbsl)
Science Update: Today the rig floor team continued to assemble the casing for Hole U1610A. The top of the 498 m casing string landed at its base and hung beneath the ship. The base will sit on the seafloor after the casing is installed to provide a firm platform and to stop the reentry funnel from subsiding. The rig team then made up the BHA, including the bit, underreamer bit, and mud motor. The underreamer and mud motor were tested and found to operate well at a pressure of 300 psi. The BHA and drill pipe were lowered down through the casing until the bit and underreamer extended below the casing by 3 m. The HRT running tool was attached to the casing and the funnel was welded on; then the whole casing system was lowered down through the moonpool and the ship was positioned over the hole coordinates. Hole U1610A started at 1200 h when the seafloor was tagged at 561.7 mbsl. From 1200 to 2400 h, the system was drilled ahead to 168.7 mbsf.
The science party met to present and discuss their scientific results from Site U1609, and they continued to write them up for the site chapter.
Daily science report for 28 December 2023
Location:
- In transit to proposed Site GUB-02A (Site U1610)
- Site U1610 (preliminary: 36°41.981′N, 7°25.885′W; water depth 556.5 mbsl)
Science Update: Today the ship completed the 122 nmi voyage to Site U1610 (proposed Site GUB-02A) at a speed of 11.5 kt, arriving at 1010 h. The thrusters were lowered and the vessel switched to DP mode, beginning operations at Site U1610. At 1030 h the rig floor team prepared the rig floor and moonpool area, and at 1200 h they started to assemble the hydraulic release tool (HRT) assembly followed by the HRT base. From 1645 to 2400 h, 498 m of 10.75 inch casing was assembled. The 3.5 kHz echosounder PDR seafloor depth of 556.5 mbsl is slightly deeper than the expected seafloor depth of 547 mbsl. Site U1610 has a target depth of 1464 mbsf, which will be among the deeper holes that the JOIDES Resolution has cored. The upper 501 m of the hole will be cased to prevent caving and to make it easier to flush cuttings out of the borehole, with the aim of increasing the chances of coring and logging successfully to target depth. The Pleistocene and late Pliocene stratigraphy that will not be recovered in the top 501 m at Site U1610 is already known from nearby Expedition 339 Site U1387, located ~27 km to the northwest.
Cores U1609B-55X to 61X were split and described. They contain calcareous mud and calcareous ooze. The science party laboratory groups began writing up their results from Site U1609 for the expedition Proceedings volume.
Daily science report for 27 December 2023
Location:
- Hole U1609B (37°22.6159′N, 9°35.9119′W; water depth 1659.5 mbsl)
- In transit to proposed Site GUB-02A (Site U1610)
Science Update: Cores U1609B-52X to 61X penetrated from 421.4 to 508.7 mbsf and recovered 85.0 m (94%). XCB coring proceeded until strata reached the age of 8.4 Ma, old enough to cover the main events in the history of the Mediterranean–Atlantic gateways. The hole provided a second copy of the stratigraphy at the site, and it covered most of the gaps in stratigraphic coverage from Hole U1609A. At 1700 h we set back the top drive and started to pull up the drill pipe. The bit cleared the seafloor at 1905 h, and the BHA was on deck by 2345 h. The thrusters were raised and we started the transit to proposed Site GUB-02A (Site U1610) at 2354 h, ending Site U1609. Overall, we spent 10.2 d at Site 1609, about two days shorter than in the original operations plan, because the age targets were shallower than had been anticipated.
Cores U1609B-40X to 55X were split and described. They contain calcareous mud, calcareous silty mud, and calcareous ooze.
Daily science report for 26 December 2023
Location: Hole U1609B (37°22.6159′N, 9°35.9119′W; water depth 1659.5 mbsl)
Science Update: Cores U1609B-39X to 51X penetrated from 292.3 to 408.7 mbsf and recovered 105.9 m (84%). At 1600 h, after taking Core 48X at 389.3 mbsf, we ran the SET2 tool to measure formation temperature. We continued to monitor stratigraphic correlation between Holes U1609A and U1609B; based on this, at 2230 h we decided that the next core, U1609B-52X, would advance 3 m rather than the usual 9.7 m to realign the gaps in Hole U1609A with cores from Hole U1609B.
Cores U1609B-23F to 39X were split and described. They contain calcareous mud and calcareous silty mud.
Daily science report for 25 December 2023
Location: Hole U1609B (37°22.6159′N, 9°35.9119′W; water depth 1659.5 mbsl)
Science Update: Cores U1609B-20F to 38X penetrated from 172.4 to 292.3 mbsf and recovered 117.5 m (98%). After Core 32F, at 234.1 mbsf, we ran the Sediment Temperature 2 (SET2) tool to measure formation temperature deeper than had been possible with the APCT-3 temperature measurements in Hole U1609A. At 1630 h we switched to the XCB coring system and recovered Cores 33X to 38X. Stratigraphic correlation was made between Holes U1609A and U1609B to check that most of the stratigraphic gaps in Hole U1609A were filled by Hole U1609B.
Cores U1609B-1H to 22F were split and described. They contain calcareous mud and calcareous silty mud. Coulometry measurements on samples from Hole U1609A showed that the bottom 80 m of the cored sediment sequence was more carbonate rich that the overlying sediments: from 0 to 530 mbsf, carbonate weight percent varied between 20% to 55%, and from 530 to 605 mbsf, from 50% to 75%.
Daily science report for 24 December 2023
Location: Hole U1609B (37°22.6159′N, 9°35.9119′W; water depth 1659.5 mbsl)
Science Update: From midnight to 0215 h, the crew serviced the drilling line and rig equipment. The ship was offset 20 m to the south of Hole U1609A and at 0305 h we started Hole U1609B by drilling down without recovery. The plan was to drill down without coring in order to spend more time coring the expedition’s late Miocene targets, but in these clay-rich sediments, drilling was not any faster downward than taking cores. At 0930 h, we retrieved the center bit and started taking APC cores at a depth of 72.6 mbsf. After Core U1609B-4H had partial recovery and required 20,000 lb overpull to retrieve, we switched to coring with the HLAPC at 101.1 mbsf. Cores U1609B-2H to 19F penetrated from 72.6 to 172.4 mbsf and recovered 102.3 m (102%).
Cores U1609A-68X to 73X were split and described. They are Tortonian in age and consist of calcareous mud with calcareous ooze interbeds.
Daily science report for 23 December 2023
Location: Hole U1609A (37°22.6259′N, 9°35.9120′W; water depth 1659.5 mbsl)
Science Update: As the day began, we were preparing for logging. The triple combo downhole logging tool string was assembled but before it could be run down the pipe, the wireline heave compensator (WHC) control computer was found to be unresponsive. After troubleshooting, we decided to log without heave compensation. Ship heave was about 2.5 m throughout the day. The triple combo logged borehole physical property data down to within 5 m of the bottom of the hole and was back on deck by 0900 h. The second tool string, the Versatile Seismic Imager (VSI), was assembled and lowered to the base of the hole. Concurrently, we slow-started the air guns and watched for protected marine species, ready for the check shot survey. Only four of the 13 check shot stations gave reliable first-arrival times, but fortunately those four stations were in the lower part of the hole where the data are most useful for tying borehole depth to the seismic profiles. The borehole width exceeded 15 inch at the other stations, so good coupling of the tool’s geophone to the borehole wall was very difficult. Because of the wide borehole and the lack of heave compensation, we decided not to run the Formation MicroScanner (FMS) tool and to run instead with a sonic velocity and NGR tool string as the third and final logging run. This tool string also reached close to the base of the hole. The logging equipment was rigged down by 2230 h. We raised the pipe and the bit cleared the seafloor at 2235 h, ending Hole U1609A.
Cores 58X to 67X were split and described. They are Tortonian in age and contain calcareous mud, calcareous ooze with clay, and calcareous ooze.
Daily science report for 22 December 2023
Location: Hole U1609A (37°22.6259′N, 9°35.9120′W; water depth 1659.5 mbsl)
Science Update: Cores U1609A-65X to 73X penetrated from 522.7 to 610.0 mbsf and recovered 81.1 m (92%). The operational objective for Site U1609 was to recover an early Pliocene to Tortonian stratigraphy and to run a suite of downhole logging tools to cover any coring gaps. Preliminary biostratigraphic results indicated that we had reached the age objective by Core 73X, so at 2015 h we stopped coring and prepared for downhole logging. The hole was swept with 30 bbl of sepiolite mud to flush out any loose sediment and then displaced with 230 bbl of barite-weighted mud to stabilize the borehole walls. By the end of the day, the end of the pipe was set at 56.4 mbsf for logging.
Cores 47X to 57X were split and described. They are Messinian to latest Tortonian in age and contain calcareous mud and calcareous ooze with clay.
Daily science report for 21 December 2023
Location: Hole U1609A (37°22.6259′N, 9°35.9120′W; water depth 1659.5 mbsl)
Science Update: Cores U1609A-53X to 64X penetrated from 406.3 to 522.7 mbsf and recovered 117.0 m (98%).
Cores 39X to 46X were split and described. They are earliest Pliocene to Messinian in age and contain calcareous mud alternating with calcareous silty mud. Cyclicity on a 2–3 m scale is apparent in the magnetic susceptibility, natural gamma radiation (NGR), and lightness measurements.
Daily science report for 20 December 2023
Location: Hole U1609A (37°22.6259′N, 9°35.9120′W; water depth 1659.5 mbsl)
Science Update: Cores U1609A-41X to 52X penetrated from 289.9 to 406.3 mbsf and recovered 114.14 m (98%). We are operating with a polycrystalline diamond compact (PDC) drill bit and a PDC XCB cutting shoe, which have been found on recent IODP expeditions to yield very good recovery of XCB cores.
Cores 21H to 38X were split and described. They are Early Pliocene in age and contain mostly calcareous mud with lesser amounts of calcareous silty mud, the two lithologies alternating on a 2–4 m scale. Foraminifera and calcareous nannofossils are well preserved in these clay-rich sediments.
Daily science report for 19 December 2023
Location: Hole U1609A (37°22.6259′N, 9°35.9120′W; water depth 1659.5 mbsl)
Science Update: Cores U1609A-23H to 40X penetrated from 201.9 to 289.9 mbsf and recovered 81.99 m (93%). Over the depth interval of Cores 23H to 25H, the clay-rich sediment became too hard for the full-length APC to fully penetrate, so we switched to the half-length APC (HLAPC) for Cores 26F to 37F. The sediment continued to become more compacted with depth and at 269.7 mbsf we changed to coring with the extended core barrel (XCB) for Cores 38X to 41X.
Cores 9H to 20H were split and described. They contain Early Pliocene calcareous mud and calcareous silty mud.
Daily science report for 18 December 2023
Location: Hole U1609A (37°22.6259′N, 9°35.9120′W; water depth 1659.5 mbsl)
Science Update: As the day began, the bit was being lowered to the seafloor at Site U1609. When the bit reached 1642.4 mbsl, the top drive was picked up and a “pig” was pumped down the drill pipe to clean out any debris from the inside. The first attempt to start the hole, from 1647.4 mbsl, resulted in an empty advanced piston corer (APC) core barrel. We lowered the bit by 5 m and, at 0430 h, we were successful in starting Hole U1609A, with the seafloor calculated at 1659.5 mbsl. We continued APC coring for the rest of the day. Temperature measurements using the advanced piston corer temperature (APCT-3) tool were made on Cores U1609A-4H, 7H, 10H, and 13H. Cores 1H to 22H penetrated from the seafloor to 201.9 meters below seafloor (mbsf) and recovered 178.9 m (89%).
Cores 1H to 8H were split and described; they contain calcareous mud and calcareous silty mud. Cores 1H to 20H are Early Pleistocene to Early Pliocene, as dated by biostratigraphy. Younger sediments are not present, which was expected from truncated reflectors in the seismic profile near the site, and it is part of the strategy to recover the target Late Miocene sedimentary succession at relatively shallow coring depths.
Daily science report for 17 December 2023
Location:
- Underway to proposed Site ALM-03B (Site U1609)
- Site U1609 (preliminary: 37°22.626′N, 9°35.915′W; water depth 1651.5 mbsl)
Science Update: The ship completed the final 204 nmi of the 1202 nmi voyage to Site U1609 (proposed Site ALM-03B) at a speed of 11.9 kt. We arrived at the site at 1654 h, lowered the thrusters, and switched from cruise mode into dynamic positioning (DP) mode. The seafloor is 1651.5 meters below sea level (mbsl), based on precision depth recorder (PDR) readings. Operations started on the rig floor with assembly of the bottom-hole assembly (BHA). At 2130 h the BHA was complete and we started adding drill pipe to lower the bit down through the water column. By 2400 h the bit had reached 1047 mbsl.
All shipboard personnel took an antigen test for COVID-19, the second of two rounds of testing as part of the current COVID-19 mitigation protocols. The science party and JRSO staff took part in a lifeboat drill. The Co-Chief Scientists gave talks to the JRSO staff about the expedition’s background and science objectives. Scientists were given a presentation on the geological and paleoceanographic setting of Site U1609, and they received training on core sampling procedures and using the Section Half Image Logger (SHIL). The scientists continued to write up their methods and prepare for core on deck.
Daily science report for 16 December 2023
Location: Underway to proposed Site ALM-03B (Site U1609)
Science Update: The ship completed 261 nmi at 11.7 kt for a total of 974 nmi of the 1202 nmi voyage to proposed Site ALM-03B (Site U1609). The scientists took guided tours of the bridge and the rig floor, and they received training on the X-ray image and section half logger instruments. Scientists continued to write up their methods and prepare their laboratories for the first core on deck, expected on 18 December.
Daily science report for 15 December 2023
Location: Underway to proposed Site ALM-03B (Site U1609)
Science Update: The ship completed 267 nmi at 11.6 kt for a total of 713 nmi of the 1202 nmi voyage to proposed Site ALM-03B (Site U1609). We expect to arrive on site late on 17 December. At 0200 h the ship’s clock was moved back one hour to be on the UTC + 0 h time zone (GMT). The scientists were given presentations on reports and publications, and on the GEODESC core and micropaleontological description software. Scientists continued to train on the instruments and procedures in their laboratories and write up their methods.
Daily science report for 14 December 2023
Location: Underway to proposed Site ALM-03B (Site U1609)
Science Update: The ship completed 267 nmi for a total of 446 nmi of the 1202 nmi voyage to proposed Site ALM-03B (Site U1609). The scientists were given presentations on coring and downhole logging operations on the JOIDES Resolution, on core and sample curation, and on the Messinian Salinity Crisis. Scientists took a guided tour of the laboratories in two groups, and they continued to train on the instruments and procedures in their laboratories. They started to transition their sleep schedules to midnight-to-noon and noon-to-midnight shifts.
Daily science report for 13 December 2023
Location:
- Berth 1, Damen Shipyard, Amsterdam, Netherlands
- Underway to proposed Site ALM-03B (Site U1609)
Science Update: The pilot boarded at 0640 h and the ship departed Damen Shipyard, with the last line released at 0718 h. The ship passed out of the IJmuiden sea lock at 1002 h. The pilot disembarked at 1054 h, and we started the sea passage to proposed Site ALM-03B (Site U1609). By midnight the ship had completed 179 nmi of the 1202 nmi voyage.
The scientists were given a presentation on IODP Expedition 339, which cored contourite depositional systems in the Gulf of Cadiz in 2011–2012 to examine Mediterranean Outflow Water and is closely related to the current expedition. Each scientist presented their research plans for the expedition and started to familiarize themselves with their laboratories and instruments.
Daily science report for 12 December 2023
Location: Berth 1, Damen Shipyard, Amsterdam, Netherlands
Science Update: All shipboard personnel took an antigen test for COVID-19 as part of the updated COVID-19 mitigation protocols. Shipboard personnel took part in a lifeboat drill, and the Captain and Ship’s Doctor gave ship safety and orientation presentations to the scientists. Scientists then took laboratory safety tours led by IODP staff and met for presentations on the science aims and outreach activities for the expedition. Some final items of freight were loaded, and the ship is scheduled to depart on 13 December.
Daily science report for 11 December 2023
Location: Berth 1, Damen Shipyard, Amsterdam, Netherlands
Science Update: Expedition 401 ship’s crew, JRSO staff, and science party cleared immigration and boarded the vessel, and fresh food was loaded aboard.
The scientists met in the conference room for introductory presentations welcoming them to the ship and the expedition, about life on board, and computing.
Daily science report for 10 December 2023
Location: Berth 1, Damen Shipyard, Amsterdam, Netherlands
Science Update: IODP Expedition 401, Mediterranean–Atlantic Gateway Exchange, officially began in the port of Amsterdam, Netherlands, at 0800 h. Port call activities included loading freight, fresh fruit, and vegetables. Most of the oncoming freight for the expedition was loaded during the tie-up period at Damen shipyard. Oncoming Expedition 401 personnel continued to arrive in Amsterdam in preparation for boarding on 11 December.