IODP Expedition 395
Reykjanes Mantle Convection and Climate
Daily science report for 30 June 2023
Location: Hole U1554H (60°7.4952′N, 26°42.1188′W; 1866.7 m water depth)
Science Update: Coring continued from 37.9 to 299.5 mbsf with Cores U1554H-5H to 32X. APC coring extended from Core 5H to 30H (37.9 to 280.1 mbsf). Core 7H was a 4.7 m advance; however, the bit was lifted off bottom to shoot the core barrel and the APCT-3 temperature tool was deployed for this core. The combination of the ship heave, the core barrel sitting in the formation for several minutes collecting temperature data, and the half-empty core barrel resulted in sediment getting sucked into the barrel and 9.41 m (200%) recovery. The temperature measurement for this core was not usable. Subsequent APCT-3 measurements during Cores 10H, 13H, and 16H appear to be of good quality. Core U1554H-24H was a partial stroke. Cores 31X and 32X (280.1 to 299.5 mbsf) were collected using the XCB system. Core recovery using the APC was 106% in Hole U1554H.
Cores U1554G-31H to 40X (278.9 to 354.97 mbsf) and U1554H-1H to 7H (0 to 66.31 mbsf) were split and described. Cores U1554G-31H to 40X are very dark gray to dark greenish gray silty clay and silty clay with biogenics. Bioturbation ranges from absent to moderate. Cores U1554H-1H to 7H are gray to dark gray silty clay and silty clay with biogenics. Bioturbation is sparse to abundant. The base of Hole U1554G is early Pleistocene in age.
Daily science report for 29 June 2023
Location:
- Hole U1554G (60°7.5037′N, 26°42.1129′W; 1868.7 m water depth)
- Hole U1554H (60°7.4952′N, 26°42.1188′W; 1866.7 m water depth)
Science Update: Coring continued from 202.9 to 288.4 mbsf with Cores U1554G-23H to 31H. Cores 30H and 31H were partial strokes and Core 31H experienced high overpull and was drilled over with the bit and BHA. After reaching refusal of the APC system, the HLAPC was deployed for Cores 32F to 34F (288.4 to 302.5 mbsf). All three cores were partial strokes. XCB coring advanced the hole from 302.5 to 355.0 mbsf, recovering Cores 35X to 40X. The target depth of the hole was achieved, and the drill string was pulled out of the hole with the bit clearing the seafloor at 1745 h, marking the end of Hole U1554G.
A total of 40 cores was taken in Hole U1554G over the 355.0 m cored interval. Core recovery was 102% and 362.3 m of sediment was collected.
The ship was offset 20 m south of Hole U1554G. At 2135 h, Hole U1554H was spudded with Core U1554H-1H recovering 9.4 m. The seafloor is calculated at 1866.7 mbsl. Cores 1H to 4H advanced to 37.9 mbsf and a temperature measurement using the APCT-3 was collected on Core 4H.
Cores U1554G-16H to 30H (136.4 to 279.13 mbsf) were split and described. These cores are predominantly very dark gray silty clay and silty clay with biogenics. Bioturbation is sparse to moderate and clasts are occasionally observed from Core 17H to 23H. These cores are Pleistocene in age.
Daily science report for 28 June 2023
Location: Hole U1554G (60°7.5037′N, 26°42.1129′W; 1868.7 m water depth)
Science Update: The drill string was lowered with the bit at 1876.0 mbrf and Hole U1554G was spudded at 0340 h. Core U1554G-1H recovered 5.43 m of sediment, establishing a seafloor depth of 1868.7 mbsl. Cores U1554G-1H through 22H were advanced to a depth of 202.90 mbsf, recovering 210.3 m of core (104% recovery).
The average ship heave during the day was >2 m, creating challenging coring conditions. The advanced piston corer temperature (APCT-3) tool was run during Core 4H, but produced noisy, poor measurements. Subsequent APCT-3 runs are postponed until the next hole. Cores 9H–13H were “misfires,” with the shear pins releasing early. The core orientation tool was removed on Cores 12H to 14H to see if that could be contributing to the misfires; the tool was redeployed beginning with Core 15H.
Cores U1564E-26X to 28X (234.4 to 263.4 mbsf) and U1554G-1H to 15H (0 to 136.73 mbsf) were split and described. Cores U1564E-26X to 28X contain very dark gray to black silty clay with sparse bioturbation. Cores U1554G-1H to 15H contain gray to very dark gray silty clay and silty clay with biogenics. Bioturbation is sparse to moderate and clasts are occasionally observed. Cores U1554G-1H to 15H are recent to Pleistocene in age.
Daily science report for 27 June 2023
Location:
- Hole U1564E (59°51.0485′N, 23°15.9876′W; 2207.3 m water depth)
- Hole U1554G (60°7.5037′N, 26°42.1129′W; 1868.7 m water depth)
Science Update: The day began while tripping the drill pipe out of Hole U1564E. At 0030 h the drill bit cleared the seafloor, and at 0545 h the bit cleared the rig floor. At 0640 h the ship was secured for transit. The thrusters were raised and the transit to Site U1554 began at 0700 h, ending Hole U1564E. Following a 104 nmi transit, the ship arrived at Site U1554 at 1800 h. The thrusters were lowered, and the vessel switched to DP mode, beginning Hole U1554G at 1842 h. An APC/XCB BHA was made up, and at the end of the day the drill string was run to a depth of 1144 meters below rig floor (mbrf).
Operations at Site U1554 occurred during two prior expeditions. Holes U1554A through U1554D were cored during Expedition 384 (2020) and Holes U1554E and U1554F were cored and logged during Expedition 395C (2021). These previous expeditions created a full stratigraphic splice for the uppermost ~70 m of the sedimentary section, cored the entire sedimentary sequence, and extended Hole U1554F 120 m into the basement. Operations at Site U1554 during Expedition 395 are focused on creating a full stratigraphic splice of the Björn Drift as deep as possible.
Cores U1564E-6H to 25X (43.08–234.48 mbsf) were split and described. The cores are very dark gray to black silty clay and silty clay with biogenics. An ash layer was observed in Core 11H.
Daily science report for 26 June 2023
Location: Hole U1564E (59°51.0485′N, 23°15.9876′W; 2207.3 m water depth)
Science Update: Coring continued from 5.8 to 205.3 mbsf with Cores U1564E-1H to 22H. It required 70,000 lb of overpull to free the core barrel from the formation on Core 22H, and the XCB was deployed for the remainder of the hole. Cores U1564E-23X to 28X extended the hole to 263.5 mbsf. The decision was made to end the hole, and the day ended with the rig crew pulling the pipe out of the hole. A total of 273.7 m of core was recovered from the 263.5 m cored interval at Hole U1564E (104%).
Cores U1564D-62X to 74X (574.84–653.01 mbsf) and U1564E-1H to 5H (0–44.16 mbsf) were split and described. Cores U1564D-64X to 74X contain greenish gray to dark greenish gray nannofossil chalk with silty clay, calcareous chalk with silty clay, and nannofossil silty clay. Bioturbation is moderate to abundant. Cores U1564E-1H to 5H contain gray to dark gray silty clay with biogenics. Initial results suggest that a complete stratigraphic splice was recovered for the uppermost ~200 at Site U1564. Below this depth there are some minor gaps, but Holes 395C-U1564C and 395-U1564D can be correlated to ~620 mbsf.
Daily science report for 25 June 2023
Location:
- Hole U1564D (59°51.0483′N, 23°16.0080′W; water depth 2208.2 m)
- Hole U1564E (59°51.0485′N, 23°15.9876′W; water depth 2207.3 m)
Science Update: Coring continued from 584.9 to 657.3 mbsf with Cores U1564D-67X to 74X. Mud sweeps were used to clean the hole following the recovery of Cores 69X and 72X. The rate of penetration (ROP) slowed and recovery in the final three cores was less than the rest of the hole (33%), due to the water jets in the cutting shoe getting clogged with sediment. The hole was terminated at a final depth of 657.3 mbsf. A total of 73 cores was collected in Hole U1564D over a 655.3 m interval, and 632.42 m of core was recovered (97%).
The drill pipe was pulled out of the hole, with the bit clearing the seafloor at 2015 h, ending Hole U1564D. The vessel was offset 20 m east and Hole U1564E was spudded at 2306 h. Core U1564E-1H recovered a 5.8 m mudline core, establishing a seafloor depth of 2207.3 meters below sea level (mbsl).
Cores U1564D-45X to 61X (377.7 to 574.84 mbsf) were split and described. The upper part of the described interval contains very dark gray silty clay with varying amounts of sand, nannofossils, and carbonate. Bioturbation in these cores ranges from sparse to moderate. Beginning in Core 52X, horizons of nannofossil ooze with silty clay are present. Cores 53X to 59X contain a mixture of gray to greenish gray silty clay and nannofossil ooze. Cores 60X and 61X transition to a greenish gray nannofossil chalk with silt, clay, or silty clay with moderate bioturbation. The cores are Pliocene to Miocene in age. Headspace gas measurements began in Core 71X. Methane concentrations range from 38 to 292 ppmv in Cores 71X to 74X.
Daily science report for 24 June 2023
Location: Hole U1564D (59°51.0483′N, 23°16.0080′W; water depth 2208.2 m)
Science Update: Cores U1564D-48X to 66X (406.8 to 584.9 mbsf) were cut, and 173.19 m of core was recovered (97%). Stratigraphic correlation between Hole 395C-U1564C and Hole U1564D continued, and the coring gaps are offset.
Cores U1564D-29F to 44X (234.5 to 377.7 mbsf) were split and described. They contain very dark gray to black silty clay, mud, and silty clay with biogenic particles or sand. The cores are Pliocene/Pleistocene in age.
Daily science report for 23 June 2023
Location: Hole U1564D (59°51.0483′N, 23°16.0080′W; water depth 2208.2 m)
Science Update: Coring with the APC system continued from Core U1564D-21H to 22H (190.0 to 209.0 mbsf), where refusal was reached and Core 22H was drilled over to recover the core barrel. The half-length APC (HLAPC) system was deployed for Cores 23F to 29F (209.0 to 239.2 mbsf). The stratigraphic correlators requested a 2 m drilled interval (26-1), from 223.2 to 225.2 mbsf, to offset coring gaps. Because of the challenges associated with covering coring gaps in sections that used the HLAPC, the XCB, using a polycrystalline diamond compact (PDC) bit and cutting shoe, was deployed as a test to see if the core quality was similar to that of the HLAPC. Core 30X was recovered, and based on initial magnetic susceptibility measurements and X-ray images, the core appeared to be in good condition and the decision was made to continue with the XCB system. At the end of the day, XCB coring had extended to 406.8 mbsf with Core 47X.
Cores U1564D-11H to 28F (95.0 to 234.86 mbsf) were split and described. They contain gray to very dark gray silty clay with varying amounts of carbonate and biogenic particles. The cores are Pleistocene in age.
Daily science report for 22 June 2023
Location: Hole U1564D (59°51.0483′N, 23°16.0080′W; water depth 2208.2 m)
Science Update: Holes U1564A through U1564C were cored during Expedition 395C, with the total hole depths ranging from 9.5 to 628.9 meters below seafloor (mbsf). The remaining operations for Site U1564 include (1) coring to piston core refusal for stratigraphic correlation, (2) replicating the record of Hole U1564C down to ~700 mbsf, and (3) installing casing and a reentry system to access the deepest sediments at this site and to core ~120 m into the basement. Downhole logging operations are planned at two of the three remaining holes.
The day began with the rig crew making up the top drive and preparing the core barrels. Hole U1564D was spudded at 0500 h with the first core on deck at 0530 h. Piston coring using the APC continued from Core U1564D-1H through 20H (0 to 190 mbsf), with 200.34 m of core recovered (105%). The stratigraphic correlators are monitoring coring gaps using data from the Special Task Multisensor Logger (STMSL), which is be being run at a low resolution.
Cores U1564D-1H to 10H (0 to 95.76 mbsf) were cut and described. The cores are Pleistocene in age and contain gray silty clay to clayey silt with biogenics and sparse bioturbation. X-ray images of the whole-round core sections show intervals that contain clasts, which are interpreted as ice-rafted debris (IRD).
Daily science report for 21 June 2023
Location:
- Underway to Site U1564 (proposed Site REYK-2A)
- Site U1564 (59°51.0360′N, 23°15.9840′W; water depth 2208.2 m)
Science Update: The vessel completed the final 160 nmi of the 1349.5 nmi journey at 1424 h. The thrusters were lowered and secured at 1456 h and the ship was fully in dynamic positioning (DP) mode at 1502 h. The rig crew removed the core barrels from their shucks, made up a 163.1 m long advanced piston corer/extended core barrel (APC/XCB) bottom-hole assembly (BHA), and began tripping the drill pipe. The first core on deck is expected at ~0600 h on 22 June.
The science party continued to work on expedition reports and train in the laboratories. The Co-Chief Scientists gave a Site U1564 overview of science and operations, followed by an introduction to stratigraphic correlation presented by the correlators. Some of the science party members participated on a ship tour in the morning.
Daily science report for 20 June 2023
Location: Underway to Site U1564 (proposed Site REYK-2A)
Science Update: The ship continued the transit to Site U1564, completing 275 nmi of the total 1349.5 nmi voyage at an average speed of 11.5 kt. The vessel is scheduled to arrive onsite at 1500 h on 21 June.
The science party began their shifts and continued to work on expedition reports and laboratory training. We held a site results meeting for Site U1555, which was cored during Expeditions 384 and 395C. The prespud meeting for Site U1564 was held in preparation for coring operations.
Daily science report for 19 June 2023
Location: Underway to Site U1564 (proposed Site REYK-2A)
Science Update: The ship continued the transit to Site U1564, completing 257 nmi of the total 1349.5 nmi voyage at an average speed of 10.7 kt. The vessel is scheduled to arrive onsite on 21 June. At 0000 h, all COVID mitigation procedures were lifted.
The science party continued to work on expedition reports and get acquainted with the laboratory spaces. Training was held in physical properties, paleomagnetism, and core description. The Microbiology Laboratory was prepared for the start of operations and a workflow for the samples was solidified by the technical staff and microbiologist. The science party was given an overview of operations and downhole logging tools, which included an introduction to the various coring and downhole tools as well as diagrams and animations. Postcruise X-ray fluorescence (XRF) core scanning discussions began with an initial meeting to determine scanning priorities. In the afternoon, some of the science party members participated in a ship tour.
Daily science report for 18 June 2023
Location: Underway to proposed Site REYK-2A (Site U1564)
Science Update: The ship continued the transit to Site U1564, completing 270 nmi of the total 1349.5 nmi voyage at an average speed of 11.3 kt. The vessel is scheduled to arrive onsite on 21 June.
The science party continued to work on expedition reports and get acquainted with the laboratory spaces. Both science shifts participated in a core flow tour, and laboratory groups began training on the physical properties tracks and using the core description application GEODESC. The chemistry group met to discuss a sampling plan for ephemeral and individual personal sample needs.
COVID-19 mitigation procedures are in place.
Daily science report for 17 June 2023
Location: Underway to proposed Site REYK-2A (Site U1564)
Science Update: The ship continued the transit to proposed Site REYK-2A (Site U1564), completing 272 nmi of the 1349.5 nmi distance at an average speed of 11.3 kt. The vessel is scheduled to arrive onsite on 21 June.
The science party participated in laboratory safety tours and was introduced to IODP curation. The remainder of the day was spent working on expedition reports and starting to work in the laboratory spaces. The first life boat drill was held in the morning.
COVID-19 mitigation procedures are in place.
Daily science report for 16 June 2023
Location:
- NATO Berth 12, Ponta Delgada, Azores, Portugal
- Underway to proposed Site REYK-2A (Site U1564)
Science Update: The final member of the science party boarded the vessel in the morning, and the Expedition 399 frozen shipments were picked up by the shipping agent. At 1333 h, the tug boats were secured to the vessel and the last line from shore was away at 1345 h. The pilot disembarked at 1404 h, and at 1418 h the vessel began the sea passage to proposed Site REYK-2A (Site U1564). The ship completed 114 nmi of the 1350 nmi transit at an average speed of 9.7 kt.
The science party learned about IODP depth scales and how to access data on the ship. The remainder of the day was spent enjoying the departure from Ponta Delgada and working on expedition reports. Following a three-year delay, Expedition 395 is underway.
COVID-19 mitigation procedures are in place.
Daily science report for 15 June 2023
Location: NATO Berth 12, Ponta Delgada, Azores, Portugal
Science Update: The unloading of freight continued with Expedition 399 third-party equipment, refrigerated sample shipments, the core shipment, and other picked-up items. In the afternoon, the ship was notified that air samples collected in the laboratory spaces both prior to and after the deep cleaning contained no trace of asbestos. The laboratories were opened and the JRSO technical staff immediately got to work reassembling laboratory equipment and computers.
The science party spent the day observing presentations, training, and working on expedition reports. Scientists attended overviews of publications as well as outreach activities. Siem Offshore crew members instructed science party members in putting on immersion suits.
The vessel is scheduled to depart at 1330 h on 16 June and COVID-19 mitigation procedures are in place.
Daily science report for 14 June 2023
Location: NATO Berth 12, Ponta Delgada, Azores, Portugal
Science Update: The loading and unloading of freight and shipments continued throughout the day. The cleaning of the laboratory spaces was concluded, and the cleaners began collecting the final air samples.
The science party was introduced to several topics throughout the day, including the expedition’s science objectives and planned operations, an introduction to a JOIDES Resolution expedition, and an introduction to the ship’s computing and network infrastructure, in addition to the Siem Offshore safety presentation and JRSO hazard communication. The scientists began connecting to the ship’s network and working on methods chapters and site reports from Expedition 395C.
COVID-19 mitigation procedures are in place.
Daily science report for 13 June 2023
Location: NATO Berth 12, Ponta Delgada, Azores, Portugal
Science Update: The IODP technical staff boarded the ship at 0900 h, followed by the science party at 1200 h. The IODP staff and Siem Offshore crew completed their crossover, and the Expedition 399 staff disembarked the vessel. The science party moved onto the ship and was given a Life at Sea presentation followed by a basic tour of the ship.
Port call activities continued with the loading of a mud motor and the professional cleaning of the laboratory spaces.
COVID-19 mitigation procedures are in place.
Daily science report for 12 June 2023
Location: NATO Berth 12, Ponta Delgada, Azores, Portugal
Science Update: Expedition 395 officially began at 0800 h. Port call activities continued with the loading of air freight and the professional cleaning of the laboratory spaces. Seven scientists from Expedition 399 disembarked the vessel. The oncoming crew and science party will board the morning of 13 June. The ship is scheduled to depart on 17 June.
Expedition 395 will investigate mantle upwelling beneath Iceland, which supports the regional bathymetry and has led to changes in the height of oceanic gateways that control the strength of deepwater flow over geologic timescales. This drilling program contains three objectives: (1) to test contrasting hypotheses for the formation of V-shaped ridges that are the result of interaction between the Mid-Atlantic Ridge and the Iceland plume; (2) to understand temporal changes in ocean circulation and explore connections with plume activity; and (3) to reconstruct the evolving chemistry of hydrothermal fluids with increasing crustal age, varying sediment thickness, and crustal architecture. Some of the operations for Expedition 395 were completed during Expeditions 384 and 395C in 2020 and 2021.