IODP Expedition 397
Iberian Margin Paleoclimate
Daily Science Report for 10 December 2022
Location: Underway to Tarragona, Spain. Midnight position 40°19.10′N, 1°22.90′E
Science Update: Today we transited 226 nmi at an average speed of 9.4 kt. We have 69.6 nmi remaining. The estimated time of arrival in Tarragona is 0700 h tomorrow, 11 December.
The expedition scientists completed all the shipboard reports and continue to submit their revised postcruise research plans.
Daily Science Report for 9 December 2022
Location: Underway to Tarragona, Spain. Midnight position 37°08.10′N, 1°05.9′W
Science Update: Today we transited 296 nmi at an average speed of 12.3 kt. We have 281 nmi remaining. The estimated time of arrival in Tarragona is 0700 h on 11 December.
The expedition scientists continued to write shipboard reports and to discuss postcruise research plans.
Daily Science Report for 8 December 2022
Location: Underway to Tarragona, Spain. Midnight position 36°01.30′N, 6°46.1′W
Science Update: The day began while recovering the drill string from 62 mbrf. The rig crew broke down the BHA, laid out the drill collars, and secured the rig floor for transit at 0138 h. The thrusters were raised, and at 0224 h the JOIDES Resolution began the sea passage to Tarragona, Spain. By midnight, we had covered 226 nmi at an average speed of 10.5 kt. We have 557 nmi remaining with an estimated time of arrival of 0700 h on 11 December.
The last cores of the expedition, Cores U1588D-69X through 76X, were split, measured, and described. They consist of clayey nannofossil ooze and nannofossil ooze. Bioturbation is light to moderate, with trace fossils observed, including Thalassinoides, Planolites, and Chondrites. Cores are moderately to strongly affected by XCB coring-induced biscuiting.
The scientific team presented the results from Site U1588 and continued to work on shipboard reports.
Daily Science Report for 7 December 2022
Location: Hole U1588D (37°57.6023′N, 9°30.9820′W; water depth 1338.5 mbsl; proposed Site SHACK-10B)
Science Update: We completed coring operations at Hole U1588D, cutting Cores 48X through 76X from 267.4 to 412.5 mbsf using half advances of the XCB coring system. The last core of Hole U1588D and of Expedition 397 was recovered on deck at 1800 h. Total core recovered in Hole U1588D was 569.44 m (138%). The rig floor crew then started to raise the drill string back on board with the bit reaching 62 mbrf by midnight.
Overall, Expedition 397 cored 5929.4 m in 16 holes at four sites (U1385, U1586, U1587, and U1588) and recovered 6176.72 m of sediment (104%).
Cores U1588D-31X through 68X were split and described. They consist of clayey nannofossil ooze and nannofossil ooze. Foraminifera, mollusk shells, and shell fragments are disseminated throughout. Pyrite nodules are common. Bioturbation is light to moderate, with trace fossils observed, including Thalassinoides, Planolites, and Chondrites. Cores are slightly to moderately affected by gas expansion and XCB coring-induced biscuiting.
The scientific team continued to analyze samples and data from Site U1588 and to work on summarizing their results in the shipboard reports.
Daily Science Report for 6 December 2022
Location: Hole U1588D (37°57.6023′N, 9°30.9820′W; water depth 1338.5 mbsl; proposed Site SHACK-10B)
Science Update: We continued APC coring in Hole U1588D, retrieving Cores U1588D-8H to 11H from 56.0 to 90.5 mbsf by 0315 h. Then we deployed the XCB system, cutting and retrieving half-length Cores U1588D-12X to 47X from 90.5 to 267.4 mbsf before the end of the day. Core recovery ranged from 109% to 123% (average 114%) for the APC section and from 121% to 180% (average 149%) for the XCB section. At 1656 h, a Siem Offshore crew member disembarked onto Portuguese tug Poseidon for repatriation.
Cores U1588C-41X through 54X and Cores U1588D-1H through 30X were split and described. They consist of clayey nannofossil ooze and nannofossil ooze. Foraminifera, mollusk shells, and shell fragments are disseminated throughout the core. Pyrite nodules are common. Bioturbation ranges from light to moderate, with trace fossils observed, including Thalassinoides, Planolites, and Chondrites. Cores are slightly to moderately affected by gas expansion and XCB coring-induced biscuiting.
The scientific team continues to analyze samples and data from Site U1588 and to work on summarizing their results in the shipboard reports.
Daily Science Report for 5 December 2022
Location:
- Hole U1588C (37°57.6160′N, 9°30.9814′W; water depth 1339.3 mbsl [offset]; proposed Site SHACK-10B)
- Hole U1588D (37°57.6023′N, 9°30.9820′W; water depth 1338.5 mbsl; proposed Site SHACK-10B)
Science Update: Cores U1588C-32X through 54X were cut with half advances using the XCB system from 238.6 mbsf to a final depth of 353.6 mbsf for the hole, recovering 145.45 m. Core recovery ranged from 103% to 156% (average 126%). Following the retrieval of Core U1588C-54X, the bit was raised, clearing the seafloor at 1650 h and ending Hole U1588C. The vessel was repositioned 20 m south and the bit was spaced out to 1345 mbrf. Hole U1588D was spudded at 1845 h. Based on the 4.51 m recovered in Core U1588D-1H, a seafloor depth of 1338.5 mbsl was calculated. APC coring continued, cutting Cores U1588D-2H through 7H to 56.0 mbsf before the end of the day.
Cores U1588C-2X through 40X were split and described. They consist of clayey nannofossil ooze and nannofossil ooze. Foraminifera, mollusk shells, and shell fragments are disseminated throughout. Pyrite nodules are common. Bioturbation is light to moderate, with trace fossils observed, including Thalassinoides, Planolites, and Chondrites. Cores are slightly to moderately affected by gas expansion and XCB coring-induced biscuiting. Rhizon sampling for interstitial water (IW) chemistry was conducted in Cores U1588D-1H through 3H.
The scientific team continues to analyze samples and data from Site U1588 and to work on summarizing their results in the shipboard reports.
Daily Science Report for 4 December 2022
Location: Hole U1588C (37°57.6160′N, 9°30.9814′W; water depth 1339.3 mbsl [offset]; proposed Site SHACK-10B)
Science Update: Owing to increased heave while the drill crew serviced the rig, we opted to follow the same strategy used at Site U1385 to avoid losing more operational time and to avoid coring the upper section of the hole under unfavorable APC coring conditions. Therefore, at 0320 h, we spudded Hole U1588C and drilled ahead without recovering core to 92 mbsf. Then, we deployed the XCB coring system and cut Cores U1588C-2X to 31X with half advances from 92.0 to 238.6 mbsf by midnight, recovering 199.6 m. Core recovery ranged from 109% to 162% (average 136%).
Cores U1588B-36X through 64X were split and described. They consist of clayey nannofossil ooze and nannofossil ooze. Foraminifera, mollusk shells, and shell fragments are disseminated throughout. Bioturbation is light to moderate, and evidence of trace fossils including Thalassinoides, Planolites, and Zoophycos is observed. Cores are slightly to strongly affected by gas expansion and XCB coring-induced biscuiting.
The scientific team continues to analyze samples and data from Site U1588 and to work on summarizing their results in the shipboard reports.
Daily Science Report for 3 December 2022
Location: Hole U1588B (37°57.6149′N, 9°30.9956′W; water depth 1339.3 mbsl; proposed Site SHACK-10B)
Science Update: Cores U1588B-28X through 64X were retrieved from 167.3 mbsf to a final depth of 350 mbsf using half advances with the XCB system, recovering 243.98 m with recovery ranging from 101% to 171% (average 134%). Because of the high gas content in the sediment, drilling half advances per core has allowed for a more controlled core expansion inside the 9.6 m liner. The total core recovered from Hole U1588B is 456.03 m (130%).
Between 2200 h and midnight, the drill pipe and the bit were raised above the seafloor and then the drill crew began conducting required routine rig servicing (drill line cut and slip) while the vessel was moved 20 m east in preparation to start Hole U1588C.
Cores U1588B-3H through 35X were split and described. They consist of clayey nannofossil ooze and nannofossil ooze. Foraminifera, mollusk shells, and shell fragments are disseminated throughout. Bioturbation is light to moderate, and evidence of trace fossils including Thalassinoides, Planolites, and Zoophycos is observed. Several cores are slightly to strongly affected by gas expansion.
The scientific team continues to analyze samples and data from Site U1588 and to work on summarizing their results in the shipboard reports.
Daily Science Report for 2 December 2022
Location: Hole U1588B (37°57.6149′N, 9°30.9956′W; water depth 1339.3 mbsl; proposed Site SHACK-10B)
Science Update: Coring in Hole U1588A was ended after retrieving Core 49X from 353.0 mbsf at 0045 h. The total core recovered from Hole U1588A is 378.37 m (107%). The drill pipe and the bit were raised above the seafloor and the vessel moved 20 m north. After picking up the top drive and positioning the bit at 1347 mbrf, Hole U1588B was spudded at 0445 h. Based on the amount of material retrieved in the mudline core (5.8 m), the seafloor was calculated to be 1339.3 mbsl, the same as for Hole U1588A. APC coring continued, cutting Cores U1588B-2H through 9H from 5.8 to 81.8 mbsf and recovering 80.06 m (105%). The XCB system was deployed with Core U1588B-10X and the hole was extended to 162.5 mbsf using half advances to allow for core expansion within the liners. At 2130 h, coring was paused for routine maintenance and 500 m from the aft core winch line were cut. Coring resumed at 2245 h, and Core U1588B-27X was retrieved from 167.3 mbsf before the end of the day. Total core recovered with the XCB system today was 126.19 m, with recovery ranging from 124% to 167% (average 148%).
Cores U1588A-25X through 49X and Cores U1588B-1H and 2H were split and described. They consist of clayey nannofossil ooze and nannofossil ooze. Foraminifera, mollusk shells, and shell fragments are disseminated throughout. Bioturbation is light to moderate, and evidence of trace fossils, including Thalassinoides, Planolites, and Zoophycos is observed. Several cores are slightly to strongly affected by gas expansion. Biostratigraphic markers provide an age between 1.92 and 2.3 Ma at the base of Core U1588A-48X.
The scientific team continues to analyze samples and data from Site U1588 and to work on the reports for Site U1385.
Daily Science Report for 1 December 2022
Location: Hole U1588A (37°57.6044′N, 9°30.9961′W; water depth 1339.3 mbsl; proposed Site SHACK-10B)
Science Update: We continued APC coring in Hole U1588A, retrieving Cores U1588A-14H through 17H from 116.2 to 154.2 mbsf by 0305 h. A partial stroke registered with Core U1588A-17H indicated we had reached APC refusal. Then we deployed the XCB system and retrieved Cores U1588A-18X to 48X before by midnight. Owing to significant gas expansion of the sediment, we changed to cutting half-length XCB cores beginning with Core 25X, to allow for the core to expand more cleanly inside the liner. In total, 159.14 m (103%) of core was retrieved with the APC system and 213.2 m (110%) was retrieved with the XCB system. For the half-length XCB cores, recovery ranged from 93% to 143% and averaged 123%.
Cores U1588A-7H through 24X were split and described. They consist of clayey nannofossil ooze and nannofossil ooze. Contacts between lithologies are bioturbated, irregular, and gradational. Foraminifera and small carbonate sand, mollusk shells, and shell fragments are disseminated throughout. Bioturbation is light to moderate, and evidence of trace fossils including Thalassinoides, Planolites, and Zoophycos is observed. Several cores are slightly to strongly affected by gas expansion. Biostratigraphic markers provide an age between 0.91 and 0.97 Ma at the base of Core U1588A-19X.
We held the Site U1385 summary meeting and presented the scientific results from each laboratory team. We then continued to analyze samples and data from Site U1588 and to work on the reports for Site U1385.