IODP Expedition 397
Iberian Margin Paleoclimate
Daily Science Report for 30 November 2022
Location: Hole U1588A (37°57.6044′N, 9°30.9961′W; water depth 1349.3 mbsl; proposed Site SHACK-10B)
Science Update: While freeing the last logging tools from the BHA, the Schlumberger engineer and the drill floor crew observed a broken piece of the bowspring centralizer of the triple combo stuck in the lockable float valve. The crew then proceeded to secure the drill floor and prepare for transit. The thrusters were raised and at 0245 h, we were underway to Site U1588 (proposed Site SHACK-10B). We arrived over the site coordinates at 0700 h, and after lowering the thrusters, the rig crew began to assemble the APC/XCB BHA and then to deploy the drill pipe to the seafloor. At 1200 h, the top drive was picked up and the bit was positioned at 1343.4 mbrf to start Hole U1588A. The hole was spudded at 1330 h, with Core U1588-1H recovering 2.18 m. Based on the recovery of the mudline core, we calculated the water depth to be 1349.3 mbsl. APC coring then continued throughout the rest of the day, retrieving Cores U1588A-2H through 13H from 2.2 to 116 mbsf with a recovery of 120.78 m (104%). Formation temperature measurements were taken with Cores U1588A-4H (30.7 mbsf), 7H (59.2 mbsf), 10H (87.7 mbsf), and 13H (116.2 mbsf).
Cores U1588A-1H through 6H were split and described. They consist of clayey nannofossil ooze and nannofossil ooze. Contacts between lithologies are bioturbated, irregular, and gradational. Bioturbation is light, and evidence of trace fossils including Thalassinoides, Planolites, and Zoophycos is observed. Core U1588A-5H is slightly affected by gas expansion.
The Staff Scientist gave an end-of-expedition presentation to lay out the tasks and the tentative schedule for the remainder of the expedition and to explain what happens after the end of the expedition, including publication of the Preliminary Report, the postcruise editorial meeting, the sampling party, the science meeting, and the manuscript submission guidelines to fulfill the obligation to conduct research and publish those results. Scientists started to analyze samples and data from Site U1588, and continued to work on the reports for Site U1385 and to prepare presentations for the Site U1385 summary meeting.
Daily Science Report for 29 November 2022
Location: Hole U1385J (37°34.0103′N, 10°07.6513′W; water depth 2593.1 mbsl; proposed Site SHACK-04C)
Science Update: We completed coring in Hole U1385J at 0415 h with Cores 42X and 43X reaching a depth of 400 mbsf. The total core recovered from Hole U1385J was 397.77 m (99%), and the total core recovered at Site U1385 was 1515.2 m (99%).
The drillers then proceeded to clean the hole by pumping 30 barrels of high-viscosity mud in preparation for downhole logging. The end of the pipe was set at 78.3 mbsf and the triple combo tool string was rigged up. At 0800 h, the tool string was deployed and lowered through the pipe, but was unable to pass through the drill bit and into the open hole. At 1300 h, after several attempts to retrieve the tool, a Kinley wireline cutter and crimper was deployed to sever the wireline. The rig floor crew spent the rest of the day recovering and racking the drill pipe back on board and laying out the Schlumberger tools.
Cores U1385J-33X through 43X were split and described. They consist of nannofossil ooze and nannofossil ooze with clay. The sediment is color-banded and shows dark patches throughout. Contacts between lithologies are bioturbated, irregular, and gradational. Bioturbation is moderate, and trace fossils including Thalassinoides, Chondrites, Planolites, and Ophiomorpha are present. Slight to moderate coring disturbance (biscuiting) is observed in most cores.
Scientists continued to analyze samples and data from Site U1385 and to work on the reports for Sites U1587 and U1385.
Daily Science Report for 28 November 2022
Location: Hole U1385J (37°34.0103′N, 10°07.6513′W; water depth 2593.1 mbsl; proposed Site SHACK-04C)
Science Update: Cores U1385J-22X through 41X were retrieved today from 188.3 to 382.3 mbsf, recovering 186.34 m (96%).
Cores U1385J-14X through 32X were split and described. They consist of nannofossil ooze and nannofossil ooze with clay. The sediment is color-banded and shows dark patches throughout. Contacts between lithologies are bioturbated, irregular, and gradational. Bioturbation is moderate, and trace fossils including Thalassinoides, Chondrites, Planolites, and Ophiomorpha are present. Slight to moderate coring disturbance (biscuiting) is observed in most cores.
Scientists continued to analyze samples and data from Site U1385 and to work on the reports for Sites U1587 and U1385.
Daily Science Report for 27 November 2022
Location:
- Hole U1385I (37°34.0205′N, 10°07.6505′W; water depth 2589.1 mbsl; proposed Site SHACK-04C)
- Hole U1385J (37°34.0103′N, 10°07.6513′W; water depth 2593.1 mbsl; proposed Site SHACK-04C)
Science Update: Coring of Hole U1385I was completed at 0200 h after retrieving Cores U1385I-15X and 16X from 133.1 to 152.5 mbsf. A total of 145.38 m of core (95%) was retrieved from Hole U1385I.
The drill string was raised above the seafloor and the vessel moved 20 m south to start a new hole. Hole U1385J was spudded at 0455 h. A seafloor depth of 2593.1 mbsl was calculated based on 3 m of material recovered in Core U1385J-1H. APC coring continued, retrieving Cores U1385J-2H through 11H from 3 to 98 mbsf, and recovering 102.53 m (105%). Because Core 11H registered a partial stroke, the XCB system was deployed, and Cores U1385J-12X through 21X were cut before midnight, retrieving 92.74 m of sediment (103%).
Cores U1385I-8H through 16X and U1385J-1H through 13X were split and described. They consist of nannofossil ooze and nannofossil ooze with clay. The sediment is color-banded and shows dark patches throughout. Contacts between lithologies are bioturbated, irregular, and gradational. Bioturbation is moderate, and trace fossils including Thalassinoides, Chondrites, Planolites, and Ophiomorpha are present. Slight to moderate coring disturbance is observed in some cores owing to gas expansion (Cores U1385J-7H through 12X) and XCB drilling-induced biscuiting.
Scientists continued to analyze samples and data from Site U1385 and to work on the reports for Sites U1587 and U1385.
Daily Science Report for 26 November 2022
Location: Hole U1385I (37°34.0205′N, 10°07.6505′W; water depth 2589.1 mbsl; proposed Site SHACK-04C)
Science Update: Drill floor operations resumed at 0900 h when the heave decreased to between 2 and 3 m. The top drive was picked up, the drill bit was positioned at 2600 mbrf, and coring in Hole U1385I started at 1103 h. Core U1385I-1H recovered 9 m (100%) and established a seafloor depth of 2589.1 mbsl. APC coring continued with Cores U1385I-2H through 11H penetrating to 104 mbsf, with core recovery ranging from 90% to 106% (average 103%). Core U1385I-11H registered a partial stroke. Following the drilling strategy employed at the two previous sites, we changed to the XCB coring system after the first partial stroke of the APC system. Cores U1385I-12X to 14X penetrated to 133.1 mbsf, but Core 14X was retrieved empty. After inspection of the core barrel, it was determined that the core catcher did not close and the core was lost. Cores 12X and 13X retrieved 9.27 m (96%) and 9.67 m (100%), respectively.
Cores U1385I-1H through 7H were split and described. They consist of nannofossil ooze and nannofossil ooze with clay. The sediment is color-banded and shows dark patches throughout. Contacts between lithologies are bioturbated, irregular, and gradational. Bioturbation is moderate, and trace fossils including Thalassinoides, Chondrites, Planolites, and Ophiomorpha are present. The top few centimeters to decimeters of several cores show slight to moderate coring disturbance (soupy).
Scientists continued to analyze samples and data from Site U1385 and to work on the reports for Sites U1587 and U1385.
Daily Science Report for 25 November 2022
Location: Site U1385 (37°34.0218′N, 10°07.6508′W; proposed Site SHACK-04C)
Science Update: We continued waiting on the heave to come down to start APC coring Hole U1385I. Heave ranged from 4.1 to 6.4 m (average 5 m) throughout the day.
Scientists continued to analyze samples and data from Site U1385 and to work on the reports for Sites U1587 and U1385.
Daily Science Report for 24 November 2022
Location: Site U1385 (37°34.0218′N, 10°07.6508′W; proposed Site SHACK-04C)
Science Update: We ended operations in Hole U1385H after the drill bit cleared the seafloor at 0015 h. We continued to raise the bit, setting it at 2565 mbrf at 0045 h. We then remained waiting on the weather over the coordinates for Hole U1385I for the rest of the day.
Cores U1385H-30X through 32X were split and described. They consist of nannofossil ooze with clay and nannofossil ooze. Foraminifera, pyrite nodules, and color-banding are disseminated throughout. Bioturbation is moderate, and trace fossils including Thalassinoides, Chondrites, Planolites, and Zoophycos are present. Biscuiting is slight to moderate.
Processing of cores and samples from Site U1385 and writing and editing of reports for Sites U1587 and U1385 are ongoing.
Daily Science Report for 23 November 2022
Location: Hole U1385H (37°34.0223′N, 10°07.6641′W; water depth 2592.4 mbsl; proposed Site SHACK-04C)
Science Update: Coring of Hole U1385H was completed at 2035 h after retrieving Cores U1385H-17X through 32X from 250.7 to 399.2 mbsf, recovering 147.94 m (100%). Total recovery from Hole U1385H is 284.97 m (100%). We then proceeded to raise the drill pipe. By midnight, the drill bit was at 53.3 mbsf.
Cores U1385H-9X through 29X were split and described. They consist of nannofossil ooze with varying amounts of clay and planktonic foraminifera. The sediment is color-banded, and pyrite nodules are disseminated throughout. Bioturbation is moderate, and trace fossils, including Thalassinoides, Chondrites, Planolites, and Zoophycos are present. XCB drilling-induced biscuiting is slight to moderate, and decimeter-scale fall-in is observed on the top of most cores.
Processing of cores and samples from Site U1385 and writing and editing of the Site U1587 reports are ongoing.
Daily Science Report for 22 November 2022
Location: Hole U1385H (37°34.0223′N, 10°07.6641′W; water depth 2592.4 mbsl; proposed Site SHACK-04C)
Science Update: After recovering Core U1385G-42X from 397.3 mbsf, we raised the drill pipe, clearing the seafloor and ending Hole U1385G at 0300 h. We offset the ship 20 m east, picked up the top drive, and spaced out the bit in preparation to spud Hole U1385H.
Owing to rapidly deteriorating weather and the sea conditions forecasted for the middle of the week, and with the goal to retrieve a complete Pliocene section in a new hole before the rough weather sets in, we decided to follow the same drilling strategy used in Hole U1385F. We drilled from the seafloor to 114.6 mbsf without recovering core and started to XCB core thereafter. Between 0845 h and midnight, we retrieved Cores U1385H-2X through 16X from 114.6 to 250.7 mbsf, recovering 137.03 m. Core recovery ranged from 90% to 132% (average 102%).
Cores U1385G-34X through 42X and U1385H-2X through 8X were split and described. They consist of nannofossil ooze with varying amounts of clay and planktonic foraminifera. The sediment is color-banded, and pyrite nodules are disseminated throughout. Bioturbation is moderate, and trace fossils, including Thalassinoides, Chondrites, Planolites, and Zoophycos, are present. XCB drilling-induced biscuiting is slight to moderate.
Processing of samples from Holes U1385F and U1385G, and writing and editing of Site U1587 reports are ongoing.
Daily Science Report for 21 November 2022
Location: Hole U1385G (37°34.0108′N, 10°07.6656′W; water depth 2592.4 mbsl; proposed Site SHACK-04C)
Science Update: Cores U1385G-24X through 42X were retrieved today, from 213 mbsf to a final depth of 397.3 mbsf for the hole. They recovered 183.08 m (99%). The total amount of core retrieved from Hole U1385G is 396.3 m (100%).
Cores U1385G-15X through 33X were split and described. They consist of nannofossil ooze with varying amounts of clay and planktonic foraminifera. The sediment is color-banded, and pyrite nodules are disseminated throughout. Bioturbation is moderate, and trace fossils, including Thalassinoides, Chondrites, Planolites, and Zoophycos, are present. XCB drilling-induced biscuiting is slight to moderate.
Daily Science Report for 20 November 2022
Location: Hole U1385G (37°34.0108′N, 10°07.6656′W; water depth 2592.4 mbsl; proposed Site SHACK-04C)
Science Update: Coring in Hole U1385G started at 0200 h with Core U1385G-1H recovering 1.77 m (98%) and establishing a seafloor depth of 2592.4 mbsl. APC coring continued with Cores U1385G-1H through 12H penetrating from the seafloor to 106.3 mbsf and retrieving 110.05 m. Core recovery ranged from 98% to 106% (average 103%). We switched to XCB coring after Core 12H. Cores U1385G-13X through 23X deepened the hole to 213.03 mbsf, retrieving 103.2 m (97%).
Cores U1385F-21X through 33X and U1385G-1H through 14X were split and described. Cores U1385F-21X through 33X consist of nannofossil ooze with varying amounts of clay and planktonic foraminifera. The sediment is color-banded, and contacts between lithologies are bioturbated, irregular, and gradational. Bioturbation is moderate, and trace fossils, including Thalassinoides, Chondrites, Planolites, and Ophiomorpha, are present. Biscuiting is present throughout and is slight to moderate. Biostratigraphic markers provide an estimated age between 4 and 5 Ma for the base of Hole U1385F.
Cores U1385G-1H through 14X consist of the same lithology observed in Hole U1385F, which is nannofossil ooze with varying amounts of clay and planktonic foraminifera.
We continued to write and edit Site U1587 reports.
Daily Science Report for 19 November 2022
Location:
- Hole U1385F (37°33.9999′N, 10°07.6587′W; water depth 2589.1 mbsl; proposed Site SHACK-04C)
- Hole U1385G (37°34.0110′N, 10°07.6644′W (preliminary); water depth 2592.4 mbsl; proposed Site SHACK-04C)
Science Update: Cores U1385F-17X through 33X were retrieved from 241.7 to 400.0 mbsf and recovered 146.55 m. Core recovery ranged from 0% (Core 27X was retrieved empty) to 102% (average 93%). Upon inspection of the core barrel used for Core 27X, it was observed that one of the core catcher fingers did not close and the check ball on top of the barrel sealed improperly, thus releasing the core while raising it through the drill pipe. Following the retrieval of Core U1385F-33X, the bit was raised, clearing the seafloor at 2335 h and ending Hole U1385F. The vessel was repositioned 20 m north over Hole U1385G coordinates by midnight.
Cores U1385F-10X through 20X were split and described. They consist of nannofossil ooze and nannofossil ooze with clay. The sediment is color-banded, and contacts between lithologies are bioturbated, irregular, and gradational. Bioturbation is moderate, and trace fossils including Thalassinoides, Chondrites, Planolites, and Ophiomorpha are present. Biostratigraphic markers suggest an age of 2.8 Ma at the base of Core U1385F-20X.
We continued to write and edit Site U1587 reports.
Daily Science Report for 18 November 2022
Location: Hole U1385F (37°34.0002′N, 10°07.6644′W; water depth 2589.1 mbsl (estimated); proposed Site SHACK-04C)
Science Update: With rough weather and sea conditions forecasted to continue through Friday evening, an alternative drilling strategy was developed to start operations at Site U1385 and to avoid falling more behind schedule. This consisted of waiting until heave diminished sufficiently to allow for drilling from the seafloor to about 100 mbsf without recovering core, and to start to XCB coring thereafter. This strategy was feasible because Expedition 339 had already drilled four holes to ~145 mbsf at this site, and the expected stratigraphy should be identical between these and Hole U1385F, allowing us to drill safely and to correlate both records relatively easily.
At 0220 h, with improved sea conditions, and using a seafloor depth of 2589.1 mbsl as calculated from the ship’s precision depth recorder (PDR), we spudded Hole U1385F. By 0445 h, we had drilled ahead with the XCB system to 96.9 mbsf and then started XCB coring. Cores U1385F-2X to 16X extended the hole to 241.7 mbsf and retrieved 144.24 m (100%).
Cores U1385F-2X through 9X were split and described. They consist of nannofossil ooze and nannofossil ooze with clay. The sediment is color-banded, and contacts between lithologies are bioturbated, irregular, and gradational. Pyritized burrows are common. Biostratigraphic markers suggest an age of 1.9 Ma at the base of Core U1385F-9X.
We continued to write and edit Site U1587 reports.
Daily Science Report for 17 November 2022
Location: Site U1385 (proposed Site SHACK-04C)
Science Update: We remained on standby with the bit at 2557.5 mbrf, waiting on the weather to improve to begin operations.
The science party presented the results from Site U1587 and continued to write their reports for the site.
Daily Science Report for 16 November 2022
Location: Site U1385 (proposed Site SHACK-04C)
Science Update: We arrived at Site U1385 at 0220 h and remained on standby, waiting on the weather to improve to begin operations.
The Co-Chief Scientists presented the scientific and operational objectives for Site U1385 (proposed Site SHACK-04C). Site U1385 (the “Shackleton Site”) was drilled during IODP Expedition 339 and retrieved a complete record of millennial-scale climate variability and of marine, ice, and terrestrial correlation for the past 1.45 Ma owing to the continuity, high sedimentation rates, and reliability of climate signals preserved in these sediments.
The overall objective of the reoccupation of Site U1385 is to extend the original record and recover a Pliocene/Pleistocene sedimentary succession that will greatly improve the precision with which marine sediment records of climate change can be correlated to and compared with ice core and terrestrial records. In addition, the working halves of the cores retrieved from Site U1385 on Expedition 339 have been largely depleted to meet the intense sampling demand for this site. The uppermost 150 m of the holes (U1385F to U1385I) planned for Expedition 397 will duplicate the original record of Site U1385 and provide new core material for future studies.
The science party continued to analyze core data and to prepare presentations for the Site U1587 summary meeting.
Daily Science Report for 15 November 2022
Location:
- Hole U1587C (37°34.8750′N, 10°21.5205′W; water depth 3479.0 mbsl; proposed Site SHACK-14A)
- Underway to Site U1385 (proposed Site SHACK-04C)
Science Update: The day began while lowering the triple combo tool string to 3475 mbrf, just a few meters above the seafloor (3490 mbrf). A downlog was started from that depth to observe the seafloor on the gamma ray curve. The downlog continued with the caliper closed until a maximum reachable depth of 4048 mbrf in Hole U1587C, roughly 10 m above the total depth of the hole (567.9 mbsf). Next, we conducted an upward pass with the caliper open at a pace of 900 ft/h over the entire open hole interval to achieve the maximum possible data resolution from the Hostile Environment Natural Gamma Ray Sonde (HNGS) of the triple combo. The caliper was closed before entering the pipe and the main pass was completed above the seafloor. Due primarily to several spots where the hole was significantly undergauge and to the inability to close the caliper fully, it was not possible to make any additional passes, so the tools were pulled to surface and rigged down at 0810 h.
The drill string was raised, clearing the seafloor and ending Hole U1587C and the site at 0850 h. The bit was raised to 2484 mbrf and at 1115 h, we started the transit to Site U1385 (proposed Site SHACK-04C), under dynamic positioning (DP) navigation mode.
The science party finalized the shipboard sampling strategy for a collaborative multidisciplinary study aimed at examining the causes of the cyclicity observed in the sedimentary succession unearthed at Site U1587. Then, we proceeded to take the “pooled” samples that will be distributed to the scientists to generate a common geochemical, sedimentological, and micropaleontological dataset immediately postexpedition.
Daily Science Report for 14 November 2022
Location: Hole U1587C (37°34.8750′N, 10°21.5205′W; water depth 3479.0 mbsl; proposed Site SHACK-14A)
Science Update: We completed XCB coring in Hole U1587C at 1900 h with Cores U1587C-53X to 61X penetrating from 490.3 to 567.9 mbsf and retrieving 73.57 m (90%). In total, 553.34 m (97%) of core was retrieved from Hole U1587C, and 1565.74 m (97%) was retrieved for the site.
Hole U1587C then was swept clean by pumping 30 barrels of high-viscosity mud in it and the drill string was raised to set the end of the pipe at 81 mbsf in preparation for downhole logging. The triple combo tool string was assembled, and the rig floor crew started deploying it at midnight.
We described Cores U1587C-51X through 61X. They consist of nannofossil ooze with varying amounts of clay. Foraminifera and small pyrite nodules are disseminated throughout. Bioturbation varies from moderate to heavy, and trace fossils such as Planolites, Zoophycos, Chondrites, Thalassinoides, and Ophiomorpha are commonly observed. The cores show slight to moderate biscuiting drilling disturbance.
We continued to measure and analyze core samples and data from Hole U1587C and write reports for Site U1587, and we gathered to discuss postcruise research plans.
Daily Science Report for 13 November 2022
Location: Hole U1587C (37°34.8750′N, 10°21.5205′W; water depth 3479.0 mbsl; proposed Site SHACK-14A)
Science Update: Cores U1587C-42X through 53X were retrieved from 379.6 to 490.3 mbsf and recovered 102.7 m. Core recovery ranged from 82% to 114% (average 94%).
Cores U1587C-37X through 50X were described. They consist of bioturbated nannofossil ooze with varying amounts of clay. Foraminifera and small pyrite nodules are disseminated throughout. Trace fossils such as Planolites, Zoophycos, Chondrites, Thalassinoides, and Ophiomorpha are commonly observed. The cores show slight to moderate biscuiting drilling disturbance.
We continued to measure and analyze core samples and data from Hole U1587C and write reports for Site U1587.
Daily Science Report for 12 November 2022
Location: Hole U1587C (37°34.8750′N, 10°21.5205′W; water depth 3479.0 mbsl; proposed Site SHACK-14A)
Science Update: Cores U1587C-26X through 41X were retrieved from 224.4 to 379.6 mbsf and recovered 156.02 m. Core recovery ranged from 96% to 102% (average 101%).
Cores U1587C-21X through 36X were split and described. They consist of bioturbated nannofossil ooze with varying amounts of clay. Foraminifera and small pyrite nodules are disseminated throughout. Trace fossils such as Planolites, Zoophycos, Chondrites, and Thalassinoides are commonly observed. The cores show slight to moderate biscuiting drilling disturbance.
We continued to measure and analyze core samples and data from Hole U1587C and write reports for Site U1587.
Daily Science Report for 11 November 2022
Location: Hole U1587C (37°34.8750′N, 10°21.5205′W; water depth 3479.0 mbsl; proposed Site SHACK-14A)
Science Update: Cores U1587C-4H through 25X were retrieved from 24.3 to 224.4 mbsf and recovered 200.1 m, with recovery ranging from 61% to 109% (overall 100%). Core U1587C-12H registered a partial stroke and overpull during retrieval. At that point, we changed to the XCB coring system and continued deepening the hole.
Cores U1587C-2H through 20X were split and described. They consist of bioturbated nannofossil ooze with varying amounts of clay and foraminifers. The sediment is color-banded, alternating between brown, gray, and greenish-gray. Pyritized burrows are common. The cores show slight to moderate biscuiting drilling disturbance.
We continue to measure and analyze core samples and data from Hole U1587C and write reports for Sites U1586 and U1587.
Daily Science Report for 10 November 2022
Location:
Hole U1587B (37°34.8650′N, 10°21.5314′W; water depth 3478.0 mbsl; proposed Site SHACK-14A)
Hole U1587C (37°34.8750′N, 10°21.5205′W; water depth 3479.0 mbsl; proposed Site SHACK-14A)
Science Update: Coring of Hole U1587B was completed at 1430 h after retrieving Cores U1587B-53X through 59X from 479.9 to 547.8 mbsf. A total of 534.27 m of core (98%) was retrieved from Hole U1587B. The drill string was raised above the seafloor at 1630 h, and the vessel was moved 20 m at 45° to start Hole U1587C. At 1915 h, after servicing the rig, we picked up the top drive and spaced the drill bit to 3486 mbrf to shoot the mudline core. Hole U1587C was spudded at 2042 h. Cores U1587C-1H through 3H advanced from the seafloor to 24.3 mbsf, recovering 24.94 m (103%). A seafloor depth of 3479 mbsl was established based on the recovery (5.29 m) in Core U1587C-1H.
Cores U1587B-51X through 59X and Core U1587C-1H were split and described. Cores U1587B-51X through 59X consist of nannofossil ooze and nannofossil ooze with clay. Minor concentrations of foraminifera and sand-size carbonate fragments are disseminated throughout. Contacts between lithologies are gradational color boundaries. Pyritized burrows and trace fossils (e.g., Planolites, Zoophycos, Chondrites, and Thalassinoides) are commonly observed. The cores show slight to moderate biscuiting drilling disturbance. Core U1587C-1H consists of clayey nannofossil ooze.
We continued to measure and analyze core samples and data from Holes U1587A and U1587B and write reports for Sites U1586 and U1587.
Daily Science Report for 9 November 2022
Location: Hole U1587B (37°34.8650′N, 10°21.5314′W; water depth 3478.0 mbsl; proposed Site SHACK-14A)
Science Update: Due to increased heave (~6 m), drilling operations stopped at 0210 h after retrieving Core U1587B-46X from 412.0 to 421.7 mbsf (85%). We raised the bit to 395 mbsf and waited for the sea conditions to improve. By 1315 h, with the heave down to 3.6 m and continuing to decrease, we resumed XCB coring and retrieved Cores U1587B-47X through 52X from 421.7 to 479.9 mbsf. Total core recovery for this interval was 50 m (86%).
Cores U1587B-43X through 50X were split and described. They consist of bioturbated foraminifer-rich nannofossil ooze and nannofossil ooze with clay. Trace fossils include Planolites, Zoophycos, Chondrites, and Thalassinoides. The cores present slight to moderate biscuiting drilling disturbance.
We continued to measure and analyze core samples and data from Holes U1587A and U1587B and write reports for Sites U1586 and U1587.
Daily Science Report for 8 November 2022
Location: Hole U1587B (37°34.8650′N, 10°21.5314′W; water depth 3478.0 mbsl; proposed Site SHACK-14A)
Science Update: Rig floor operations resumed at 0215 h after the heave lessened sufficiently. We washed down from 282.2 to 303.3 mbsf and deployed the XCB coring system. By midnight, Cores U1587B-34X to 45X had deepened the hole from 303.3 to 412 mbsf, recovering 104.85 m (96%).
Cores U1587B-34X through 42X were split and described. They consist of interbedded bioturbated foraminifer-rich nannofossil ooze and nannofossil ooze with clay. Trace fossils include Planolites, Zoophycos, Chondrites, and Thalassinoides. The cores present slight to moderate biscuiting drilling disturbance.
We continued to measure and analyze core samples and data from Holes U1587A and U1587B and write reports for Sites U1586 and U1587.
Daily Science Report for 7 November 2022
Location: Hole U1587B (37°34.8650′N, 10°21.5314′W; water depth 3478.0 mbsl; proposed Site SHACK-14A)
Science Update: Because of the high heave (over 6 m), coring remained suspended for the entire day.
In the afternoon, we received notice that our request to extend the penetration depth from 500 to 550 mbsf at Site U1587 was approved by the IODP Environmental Protection and Safety Panel. The rationale behind our request for extending the record at this site was based on the successful recovery of a complete, well-dated, and continuous Pleistocene to late Miocene sedimentary record in Hole U1587A. The late Miocene represents a critical time in Earth’s history when the Mediterranean became isolated from the Atlantic, leading to the Messinian salinity crisis (5.96 to 5.33 Ma). Drilling an additional 50 m below the Tortonian/Messinian boundary would allow us to recover a complete record of the time leading up to, during, and following the salinity crisis, and to evaluate the causes and consequences of this remarkable event.
Cores U1587B-24X through 33X were split and described. They consist of light to heavily bioturbated nannofossil ooze with varying amounts of clay and foraminifers. The sediment is color-banded, alternating between brown, gray, and greenish-gray, with common pyritized burrows. The cores show slight to moderate drilling disturbance (biscuiting).
We started to discuss postcruise research related to Site U1586, and we continued to measure and analyze core samples and data from Holes U1587A and U1587B and edit the reports for Site U1586.
Daily Science Report for 6 November 2022
Location: Hole U1587B (37°34.8650′N, 10°21.5314′W; water depth 3478.0 mbsl; proposed Site SHACK-14A)
Science Update: Cores U1587B-15X through 33X were retrieved from 133.4 to 303.3 mbsf before high heave led us to pause coring at 2230 h. These cores recovered 171.0 m (100%). We raised the bit from 303.3 to 282.8 mbsf and waited for sea conditions to improve.
Cores U1587B-9H through 23X were split and described. They consist of light to heavily bioturbated nannofossil ooze with varying amounts of clay and foraminifers. The sediment is color-banded, alternating between brown, gray, and greenish-gray. Pyritized burrows are common. The cores show slight to moderate drilling disturbance (biscuiting).
We continued measuring and analyzing core samples and data from Holes U1587A and U1587B and editing the reports for Site U1586.
Daily Science Report for 5 November 2022
Location:
Hole U1587A (37°34.8602′N, 10°21.5400′W; water depth 3480.5 mbsl; proposed Site SHACK-14A)
Hole U1587B (37°34.8650′N, 10°21.5314′W; water depth 3478.0 mbsl; proposed Site SHACK-14A)
Science Update: At 0200 h, we retrieved the last core (53X) for Hole U1587A from 492.6 to 500 mbsf, with a recovery of 6.65 m (90%). The total amount of core retrieved from Hole U1587A is 478.13 m, with recovery ranging from 2% to 108%, an average of 96%. We then proceeded to raise the drill bit, clearing the seafloor at 0350 h, and positioned the bit at 3489 mbrf to start Hole U1586B. At 0730 h, we spudded the hole, retrieving 9.25 m in the mudline core. Based on the recovery of Core U1587B-1H, we calculated a seafloor depth of 3478.0 mbsl. Coring continued with the APC system until 1845 h through Core U1587B-11H (104.3 mbsf), which recorded a partial stroke. We then changed to XCB coring and cut Cores U1587B-12X to 14X. While retrieving Core U1587B-14X, a kink in the forward winch core line forced us to temporarily stop coring. The drill crew then changed to the aft core winch and retrieved the core by midnight.
Cores U1587A-50X through 53X and U1587B-1H through 8H were split and described. Cores U1587A-50X through 53X consist of interbedded bioturbated foraminifer-rich nannofossil ooze and nannofossil ooze with clay. Trace fossils include Planolites, Zoophycos, Chondrites, and Thalassinoides. The cores are moderately disturbed by biscuiting drilling disturbance. Cores U1587B-1H through 8H consist of light to heavily bioturbated nannofossil ooze with varying amount of clay and foraminifers. The sediment is color-banded, alternating between brown, gray, and greenish-gray. Black patches and black stained burrows are noted throughout.
We continue to measure and analyze core samples and data from Holes U1587A and U1587B and write and review the reports for Site U1586.
Daily Science Report for 4 November 2022
Location: Hole U1587A (37°34.8602′N, 10°21.5400′W; water depth 3480.5 mbsl; proposed Site SHACK-14A)
Science Update: We retrieved Cores U1587A-42X to 52X from 385.9 to 492.6 mbsf. They recovered 89.07 m, with recovery ranging from 55% to 95%, an average of 83%. While retrieving Core U1587A-44X at 0445 h, a kink in the core winch line would not let the sinker bars pass 957 mbrf. After several attempts to clear the cable, it had to be pulled back to the rig floor and 1000 m cut off. The cable was reheaded, and at 0715 h, Core 44X was retrieved and coring continued without further incident.
Cores U1587A-33X through 49X were split and described. They consist of light to heavily bioturbated nannofossil ooze with clay. Trace fossils such as Planolites, Zoophycos, and Chondrites are common throughout the sequence. Small pyrite nodules are present as well. The cores are moderately disturbed by biscuiting drilling disturbance.
We continue to measure and analyze core samples and data from Hole U1587A and write the reports for Site U1586.
Daily Science Report for 3 November 2022
Location: Hole U1587A (37°34.8602′N, 10°21.5400′W; water depth 3480.5 mbsl; proposed Site SHACK-14A)
Science Update: Cores U1587A-24X through 41X were retrieved from 211.3 to 385.9 mbsf. They recovered 165.43 m, with recovery ranging from 2% to 102%, an average of 95%. Although Core U1587A-27X was drilled 9.5 m, we only recovered 16 cm. We speculate that the cored material was lost due to a faulty core catcher. All subsequent cores were cut and retrieved with more than 98% recovery.
Cores U1587A-14H through 32X were split and described. They consist of light to heavily bioturbated nannofossil ooze with clay. Trace fossils, mainly Zoophycos, Planolites, and Chondrites, are common throughout the sequence. A few cores show fall-in in the top section. Most XCB cores show slight drilling disturbance (biscuiting).
We continue to measure and analyze core samples and data from Hole U1587A and write the reports for Site U1586.
Daily Science Report for 2 November 2022
Location: Hole U1587A (37°34.8602′N, 10°21.5400′W; water depth 3480.5 mbsl; proposed Site SHACK-14A)
Science Update: Cores U1587A-3H through 23X were retrieved from 12.3 to 211.3 mbsf. They recovered 204.57 m, with recovery ranging from 89% to 108%, an average of 103%. Formation temperature measurements were taken with Cores U1587A-4H (31.3 mbsf), 7H (59.8 mbsf), 10H (88.3 mbsf), and 13H (116.8 mbsf). Coring with the XCB system began on Core U1587A-16X after recording a partial stroke on Core U1587A-15H.
Cores U1587A-1H through 13H were split and described. They consist of light to heavily bioturbated nannofossil ooze with varying amount of clay. The sediment is color-banded, alternating between brown, gray, and greenish-gray. Black patches and black stained burrows are noted throughout. Core drilling disturbance includes slurry sediment near the top of some cores and slight uparching. Core 6H was severely disturbed due to an early core barrel deployment.
We continue to measure and analyze core samples and data from Hole U1587A and write the reports for Site U1586.
Daily Science Report for 1 November 2022
Location:
Hole U1586D (37°37.2835′N, 10°42.6289′W; water depth 4693.6 mbsl; proposed Site SHACK-11B)
Hole U1587A (37°34.8602′N, 10°21.5400′W; water depth 3480.5 mbsl; proposed Site SHACK-14A)
Science Update: By 0815 h, the drill pipe and the APC/XCB BHA had been retrieved, and the stuck logging tools were removed, inspected, and laid out. The rig floor was secured for transit and the thrusters were pulled up to start the short transit (16.9 nmi) to Site U1587 (proposed Site SHACK-14A). We arrived over the site coordinates at 1121 h, and after lowering the thrusters, the rig crew began to assemble the APC/XCB BHA and deploy the drill pipe to the seafloor. At 2030 h, the top drive was picked up and the bit was positioned at 3481 mbrf to start Hole U1587A. The first core was retrieved empty. The bit was repositioned to 3485 mbrf for a second attempt. This time we recovered 2.77 m, successfully spudding Hole U1587A at 2243 h. Based on the core recovery, we determined the water depth to be 3480.5 mbsl (24.5 m deeper than anticipated). We retrieved Core U1587A-2H (2.8 to 12.3 mbsf, 101% recovery) before midnight.
At noon, we held the Site U1586 summary meeting and presented and discussed the results from each laboratory team. We continued to analyze core samples and data and write the reports.