IODP Expedition 395
Reykjanes Mantle Convection and Climate
Daily science report for 31 July 2023
Location: Hole U1564F (59°51.036′N, 23°15.984′W; water depth 2208.2 m)
Science Update: Coring continued with Cores U1564F-5R to 17R recovering 116.66 m of core from 627.2 to 753.0 mbsf (93% recovery).
Cores U1564F-2R to 13R (598.0–714.52 mbsf) were split and described. The primary lithologies include greenish gray silty claystone, nannofossil chalk, and clayey chalk. Bioturbation is observed throughout, and glass and sharp boundaries are found within this interval. The cores contain natural fractures, some with slickensides, that were measured and documented. The cores are Miocene in age.
Daily science report for 30 July 2023
Location: Hole U1564F (59°51.036′N, 23°15.984′W; water depth 2208.2 m)
Science Update: After breaking down the reentry installation equipment, the RCB BHA was made up with a C-4 drill bit. The drill pipe was run to a depth of 1598.7 mbsl. The subsea camera system, with the CTD and Niskin bottles attached, was deployed through the moonpool at 0845 h and the drill pipe was filled with water. The drill string continued to be lowered to several meters above the seafloor. The reentry cone for Hole U1564F was found, and the bit reentered the hole at 1052 h. The subsea camera was recovered while the drill string was lowered to the base of the hole and the top drive picked up. The center bit was deployed, and the hole was conditioned with 20 barrels of high viscosity mud. The hole was advanced without recovery from 553.4 to 598.0 mbsf. The center bit was retrieved and an RCB core barrel was deployed. Cores U1564F-2R to 4R (598.0–627.2 mbsf) were recovered and Core 4R had no recovery.
The laboratory groups worked on reports for Site U1602 and prepared for operations at Site U1564. A results meeting for Site U1602 was held in the afternoon.
Daily science report for 29 July 2023
Location: Hole U1564F (59°51.036′N, 23°15.984′W; water depth 2208.2 m)
Science Update: The casing string was drilled to 554.5 mbsf. The go-devil was pumped down the pipe to release the casing stinger from the reentry system. The drill pipe was pulled up 20 m to ensure that the underreamer and mud motor entered the casing string without issue. The subsea camera system was retrieved, and the drill string was pulled to the surface. The bit cleared the seafloor at 1440 h and the rig floor at 2230 h. The day ended while breaking down the reentry installation equipment.
The laboratory groups worked on reports for Site U1602 and prepared for operations at Site U1564. The paleomagnetists are running additional measurements on discrete cubes from Site U1602, and sediment samples are being measured on the inductively coupled plasma–atomic emission spectroscopy (ICP-AES) instrument.
Daily science report for 28 July 2023
Location: Hole U1564F (59°51.036′N, 23°15.984′W; water depth 2208.2 m)
Science Update: The casing string continued to be made up to a length of 550 m. The HRT running tool was installed to lower the casing to the guide base in the mudskirt on the moonpool doors. The running tool was pulled back up to the rig floor. The casing stinger, made up of the drill bit, mud motor, underreamer, and drill pipe, was run through the casing. The cup packer—a device that prevents cuttings from filling the casing—and the HRT running tool were attached to the stinger and lowered to the moonpool and bolted to the guide base. The reentry cone was then welded to the guide base. At 1200 h, the moonpool doors were opened and the guide base with the reentry cone was lowered below the ship. The rig crew began making up the drill string to a depth of 2180 mbsl. The subsea camera system, along with Niskin water samplers and the Conductivity-Temperature-Depth (CTD) tool, was deployed at 1730 h. At 1800 h the upper guide horn was installed. The top drive was picked up and the bit spaced out to initiate Hole U1564F at 2125 h. At the end of the day, the bit and casing had advanced to 120.3 mbsf.
The laboratory groups revised reports for Site U1562 and worked on reports for Site U1602. They are also revisiting four cores from Hole U1564D to constrain the timing of a lithological transition.
Daily science report for 27 July 2023
Location: Site U1564 (proposed site REYK-2A; 59°51.036′N, 23°15.984′W)
Science Update: The vessel continued to WOW for most of the morning. At 0823 h, the Icelandic Coast Guard vessel, Thor, arrived for the transfer of severing tools, supplies, and fresh produce. Thor pulled alongside the vessel and the portside aft crane was used to transfer six pallets onto the helideck starting at 0902 h. By 0919 h, the transfer was complete, and Thor departed at 0925 h. The rig crew began preparing for the casing installation operations. The mud motor and underreamer assembly were made up and tested. After a successful test, this assembly was racked in the derrick. The rig crew began assembling and welding the casing string. By the end of the day, 375 m of the 550 m casing string was made up.
The laboratory groups revised reports for Site U1562 and worked on reports for Site U1602.
Daily science report for 26 July 2023
Location: Site U1564 (proposed site REYK-2A; 59°51.036′N, 23°15.984′W)
Science Update: The rig crew finished assembling the HRT casing running stand. The weather was forecasted to deteriorate throughout the day with ~5 m heave, preventing the assembly of the casing and reentry system. The vessel began waiting on weather (WOW) at 0200 h. At 1500 h, the Icelandic Coast Guard offshore patrol vessel, Thor, arrived to deliver severing devices and other supplies. After nearly 2 h, the transfer was postponed due to weather. Thor remained in the area to attempt the transfer the following day.
The laboratory groups revised reports for Site U1562 and worked on reports for Site U1602.
Daily science report for 25 July 2023
Location: Site U1564 (proposed site REYK-2A; 59°51.036′N, 23°15.984′W)
Science Update: After completing the 448 nmi transit at 2030 h, the thrusters were lowered and the ship was under DP mode at 2106 h, resuming operations at Site U1564. The rig crew made up the hydraulic release tool (HRT) in preparation of deploying a reentry and casing system.
The laboratory groups revised reports for Site U1562 and worked on reports for Site U1602.
Daily science report for 24 July 2023
Location:
- Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
- In transit to Site U1564 (proposed Site REYK-02A)
Science Update: The rig crew continued to bring the drill pipe to the surface and to break down the BHA. At 0345 h, the end of the pipe cleared the rig floor. The drill floor was secured for transit and the vessel was put into cruise mode at 0409 h, marking the end of Site U1602. At 0423 h, the thrusters were secured, and the vessel began the transit to Site U1564. The vessel completed 218 nmi of the 448 nmi transit and is expected to be on site at 2200 h on 25 July.
The laboratory groups submitted reports for Site U1562 and worked on reports for Site U1602.
Daily science report for 23 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: The day began with lowering the drill string into Hole U1602E to recover the triple combo logging tool string. At 430 h the pipe became stuck at a depth of 742 mbsf. After nearly 1.5 h of working the drill string and circulating water, the drill pipe was freed. The hole was cleaned with heavy mud and operations resumed. At 1300 h the end of the pipe reached the triple combo tool string at a depth of 1079 mbsf. The drill pipe was maneuvered around the tool string, which was then pulled into the pipe. The rig floor crew prepared the rig for pulling up the tools using the core winch line while water continued to be pumped down the pipe using a circulating sub. The tools arrived at the rig floor at 1645 h. The top drive was made up to circulate water and rotate the drill pipe while the triple combo tool string was broken down. After pumping a mud sweep, the drill string was pulled from the hole with the end of the pipe clearing the seafloor at 2135 h.
The laboratory groups spent the day working on site reports and analyzing the final samples from Hole U1602E.
Daily science report for 22 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: After releasing the RCB bit at the bottom of the hole, the drill pipe was pulled up to 77.8 mbsf. The triple combo logging tool string was made up. The triple combo measures porosity, natural gamma ray (NGR), magnetic susceptibility (MS), density, and resistivity. The tools were run to a maximum depth of 1270 mbsf, at which point the tool string was unable to descend farther into the hole. The calipers were opened for the first pass up the hole and the tool string immediately became stuck. The calipers were closed but the tool remained trapped in the hole. After attempting to free the tool for over an hour, the wireline cable was cut at the surface and connected to the core winch line to pull on the line with more force. The tool string was briefly freed and it ascended 160 m before getting stuck again. The decision was made to run the drill pipe back down the hole and to move the drill pipe over and around the stuck tool string. At the end of the day, the end of the pipe was at 334.3 mbsf.
The laboratory groups spent the day working on site reports and analyzing the final samples from Hole U1602E.
Daily science report for 21 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: Coring continued with Cores U1602E-83R to 88R, recovered from 1315.3 to 1365.2 mbsf. The rate of penetration (ROP) slowed to ~3.6 m/h on average and core recovery for this interval was only 32%. Due to time constraints, coring at Hole U1602E was terminated following the recovery of Core 88R and the rig floor began to prepare for downhole wireline logging operations.
In total, 87 cores were collected from Hole U1602E over an 835.9 m interval with 54% core recovery.
Cores U1602E-83R to 88R (1315.3 to 1357.99 mbsf) were split and described. While the primary lithology over this interval is sandstone, several other types are identified: mudstone, claystone with chalk, siltstone, silty claystone, and nannofossil chalk. Much like the lithology, the color of the rocks is variable and includes gray, bluish/greenish gray, very dark greenish gray, greenish black, and black. Soft sediment deformation, laminations, graded bedding, rip-up clasts, and fractures are observed in these cores. The age for the base of the hole appears to be near the Eocene/Oligocene boundary.
Daily science report for 20 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: Coring continued with Cores U1602E-74R to 82R, recovered from 1228.2 to 1315.3 mbsf. The core recovery over this interval is 43%.
Cores U1602E-73R to 82R (1218.4 to 1311.53 mbsf) were split and described. The primary lithology is a gray to dark greenish gray sandstone. Additional lithologies include silty claystone, siltstone, and small intervals of nannofossil chalk. Graded bedding, mud drapes, lamination, and soft sediment deformation are observed. Bioturbation is absent to sparse. Some of the sandstone beds contain sand-sized basalt fragments. The cores are Oligocene in age.
Daily science report for 19 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: Coring continued with Cores U1602E-67R to 73R, recovered from 1160.2 to 1228.2 mbsf. The core recovery over this interval is 35%.
Cores U1602E-66R to 72R (1150.5 to 1213.17 mbsf) were split and described. The major lithologies are gray or greenish gray siltstone with sand, sandstone, and silty claystone. Nannofossil chalk is occasionally observed. These cores display normal and reverse graded bedding, laminations, and cross-bedding. Bioturbation is absent to sparse.
Daily science report for 18 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: Coring continued with Cores U1602E-60R to 66R, recovered from 1092.1 to 1160.2 mbsf. The core recovery over this interval dropped to only 31%.
Cores U1602E-60R to 65R (1092.1 to 1143.38 mbsf) were split and described. These cores contain a complex section that is composed of nannofossil chalk, nannofossil silty claystone, sandstone, mudstone, and siltstone. These various interbedded lithologies contain several sedimentary structures, such as normal and reverse graded bedding, laminations, soft sediment deformation, sand injection, and possible mud drapes and rip-up clasts (or at least something similar). The base of Core 60R yielded an age of middle Miocene.
Daily science report for 17 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: Coring continued with Cores U1602E-52R to 59R, recovered from 1014.2 to 1092.1 mbsf. The core recovery over this interval is 56%.
Cores U1602E-51R to 59R (994.8 to 1084.62 mbsf) were split and described. Across this cored interval, the lithology transitions downhole from silty chalk, to chalk with silt, to chalk. The chalk is interbedded with sandstone beds that range in thickness from a few centimeters to >20 cm. Laminations, cross-bedding, graded beds, and soft sediment deformation are observed.
Daily science report for 16 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: Coring continued with Cores U1602E-41R to 51R, recovered from 907.8 to 1014.2 mbsf. The core recovery over this interval is 54%.
Cores U1602E-40R to 50R (898.1 to 1004.5 mbsf) were split and described. The primary lithology is silty claystone that ranges in color from dark gray or dark greenish gray to black. Secondary lithologies include silty claystone with nannofossils or calcite, siltstone, sandstone, and mudstone. Bioturbation is moderate to abundant in the silty claystone, and intervals with laminations, soft sediment deformation, and graded bedding are present. Green mottling in the cores is often observed.
Daily science report for 15 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: Coring continued with Cores U1602E-29R to 40R, recovered from 791.3 to 907.8 mbsf. The core recovery over this interval is 65%.
Cores U1602E-29R to 39R (791.3 to 898.14 mbsf) were split and described. The cores are predominantly dark gray to black silty claystone with or without nannofossils, with moderate bioturbation. Laminations and dark green mottling are observed throughout. A 16 cm layer of sandstone is within Core 34R. Below this core, small (<5 cm) sandstone and siltstone layers are occasionally observed. The cores contain fractures with slickensides.
Daily science report for 14 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: Coring continued with Cores U1602E-16R to 28R, recovered from 665.4 to 791.3 mbsf. The core recovery over this interval is 60%.
Cores U1602E-16R to 28R were split and described. These cores are primarily very dark gray to black silty clay/claystone. Additionally, silty clay with nannofossils, clay with silt, and sandy claystone are observed. An ~40 cm sandstone layer with graded bedding topped by soft sediment deformation is found in Core 22R. Intervals of laminations and green mottling are present throughout the described section. The base of the hole is late Miocene in age.
Daily science report for 13 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: Coring in Hole U1602E began at 529.3 mbsf after drilling down without recovery. Cores 2R to 15R (529.3 to 665.4 mbsf) were recovered over the day, containing 100.12 m of sediment (74%).
Cores U1602E-2R to 15R were split and described. Cores 2R to 4R alternate between very dark gray to black silty clay and greenish gray to dark greenish gray silty clay with nannofossils. Cores 5R to 7R are predominantly very dark gray to black clayey silt. Cores 8R to 15R are composed of very dark gray to black silty clay. Green banding, laminations, and pyrite are observed in intervals throughout the cored section. The base of the hole is tentatively early Pliocene to late Miocene in age.
Daily science report for 12 July 2023
Location: Hole U1602E (61°11.7150′N, 38°10.7961′W; 2709.2 m water depth)
Science Update: The morning was spent assembling the drill string in preparation to start Hole U1602E, which was spudded at 0630 h. A seafloor depth of 2709.2 mbsl was used based upon Hole U1602B, which recovered the best-preserved mudline core. The hole was advanced without recovery to a depth of 529.3 mbsf, the center bit was retrieved, and the first RCB was deployed.
The science laboratory teams spend the day finishing measurements from Hole U1602D and writing science reports.
Daily science report for 11 July 2023
Location: Hole U1602D (61°11.7259′N, 38°10.7967′W; 2709.1 m water depth)
Science Update: Coring continued with Cores U1602D-63X to 66X recovered from 501.9 to 540.7 mbsf. The cutting of Core 66X was very slow compared to the other XCB cores. When the core barrel was retrieved it was immediately noticed that the XCB cutting shoe was severely damaged with large pieces missing. Coring could not continue because the location of the broken metal from the cutting shoe was not known. Hole U1602D was terminated at a depth of 540.7 mbsf. The drill string was pulled from the hole with the bit clearing the seafloor at 1130 h. The vessel was offset 20 m south of Hole U1602D and the drill pipe and BHA continued to be pulled up to the surface. At 1630 h, the bit cleared the rig floor ending Hole U1602D. The BHA for the rotary core barrel (RCB) was made up in anticipation of RCB coring.
A total of 450.45 m of sediment was recovered from a 540.7 m cored interval (83%) at Hole U1602D.
Cores U1602D-57X to 66X (443.7 to 532.36 mbsf) were split and described. The primary lithologies are dark gray to black silty clay and silty clay with nannofossils. Also observed are silt, silty clay with carbonate, and silt with sand. Laminations, graded beds, and green mottling are seen throughout the cores.
Daily science report for 10 July 2023
Location: Hole U1602D (61°11.7259′N, 38°10.7967′W; 2709.1 m water depth)
Science Update: Coring continued with Cores U1602D-45X to 62X, recovered from 327.3 to 501.9 mbsf. Core recovery was highly variable, ranging from extremely low (0% and 3% for Cores 55X and 53X, respectively) to 101%.
Cores U1602D-32F to 56X (232.2 to 404.17 mbsf) were split and described. The primary lithology is a very dark gray, greenish gray, or black silty clay. Secondary lithologies include silty clay with biogenics and silt with sand. From Core 45X to 56X, silty clay with nannofossils becomes more common. Laminations and graded beds are observed throughout. Bioturbation is sparse. The base of Core 62X is late Miocene in age.
Daily science report for 9 July 2023
Location: Hole U1602D (61°11.7259′N, 38°10.7967′W; 2709.1 m water depth)
Science Update: Coring continued with Core U1602D-19H, recovered from 166.3 to 175.8 mbsf. This core was a partial stroke, and the HLAPC was deployed for Cores 20F to 37F to a depth of 260.4 mbsf. Piston coring refusal was reached on Core 37F with a partial stroke. The XCB system was used to cut Cores 38X to 44X (240.0 to 327.3 mbsf).
Cores U1602D-9H to 31F (76.1 to 232.55 mbsf) were split and described. Cores 9H to 21F contain very dark gray, dark greenish gray, and black silty clay. Minor lithologies include silt with sand, silty clay with biogenics, and sand. Intervals with laminations, graded beds, and clasts are observed throughout. Cores 22F to 31F are nearly exclusively dark gray, dark greenish gray, and black silty clay. Centimeter-scale silt beds are frequently observed in this interval, along with laminations, cross-bedding, and clasts. The base of Core 44X is Pliocene in age.
Daily science report for 8 July 2023
Location:
- Hole U1602C (61°11.7253′N, 38°10.8191′W; 2710.0 m water depth)
- Hole U1602D (61°11.7259′N, 38°10.7967′W; 2709.1 m water depth)
Science Update: Coring in Hole U1602C continued with the recovery of Cores U1602C-36F to 39F (250.0 to 269.3 mbsf). After 100,000 lb of overpull on Core 38F and a partial stroke on Core 39F, APC refusal had been reached and the hole ended. The drill pipe was pulled out of the hole and the bit cleared the seafloor at 0525 h, ending Hole U1602C. The vessel was offset 20 m to the east and Hole U1602D was spudded at 0805 h. The seafloor depth was determined based on the recovery of Core U1602D-1H, which was 9.6 m. Cores 1H to 18H advanced from 0 to 166.3 mbsf. A partial stroke was recorded on Core 17H, and Core 18H required 100,000 lb of overpull to free it from the formation.
Cores U1602C-21F to 39F (180.0 to 369.19 mbsf) and Cores U1602D-1H to 8H (0 to 76.54 mbsf) were split and described. Cores U1602C-21F to 39F contain predominantly very dark gray, dark greenish gray, and black silty clay. There are intervals of clay with silt and sand. Cores U1602D-1H to 8H contain dark gray to very dark gray silty clay. Cores from both holes contain laminations, graded beds, and clasts.
Daily science report for 7 July 2023
Location: Hole U1602C (61°11.7253′N, 38°10.8191′W; 2710.0 m water depth)
Science Update: Coring in Hole U1602C continued with the recovery of Cores U1602C-7H to 20H (54.5 to 180.0 mbsf). Within this cored interval, 2 m were drilled without recovery (64.0 to 66.0 mbsf) to offset coring gaps for stratigraphic correlation. After three partial strokes using the APC system, the HLAPC was deployed for Cores U1602C-21F to 35F (180.0 to 250.0 mbsf). One partial stroke was recorded on Core U1602C-23F.
Cores U1602B-37F to 38F (241.7 to 251.45 mbsf) and U1602C-1H to 20H (0 to 175.72 mbsf) were split and described. Cores U1602B-37F to 38F contain dark gray to very dark gray silty clay, with or without nannofossils, and clay with silt. The dominant lithology of Cores U1602C-1H to 17H is silty clay. Minor lithologies include silty clay with biogenics or carbonate, sand, clay, and clay with silt and nannofossils. Laminated and cross-bedded intervals are observed as well as graded beds.
In Cores U1602C-18H to 19H, intervals of laminations are still present, but few graded beds and no cross-bedding are observed. These cores contain small, centimeter-scale silt layers that are predominantly composed of quartz. Core U1602C-20H contains a ~2 m thick black sand bed. Clasts are observed between Cores 1H and 18H. Carbonate preservation varies throughout the section, and barren intervals are present. Bioturbation is absent to moderate throughout, and clasts are occasionally observed throughout the section.
Daily science report for 6 July 2023
Location:
- Hole U1602B (61°11.7144′N, 38°10.8184′W; 2709.2 m water depth)
- Hole U1602C (61°11.7253′N, 38°10.8191′W; 2710.0 m water depth)
Science Update: Coring with the HLAPC continued from Core U1602B-21F to 38F (166.5 to 251.5 mbsf). Core 26F was a partial stroke and the overpull on Core 38F was 80,000 lb, leading to the termination of Hole U1602B as piston coring refusal was reached. A total of 38 cores were collected from Hole U1602B, with 262.37 m of core recovered over a 251.1 m interval (104%).
The drill string was pulled from the hole, with the bit clearing the seafloor at 1600 h, marking the end of Hole U1602B. The vessel was offset 20 m to the north. After performing maintenance on the rig and cutting off 150 m of core winch line, the top drive was picked up and the bit spaced out to a depth of 2719 mbrf. Hole U1602C was spudded at 1920 h. Core U1602C-1H recovered 7.07 m of core, placing the seafloor at 2710.0 mbsf. Coring continued through Core 6H to a depth of 54.5 mbsf.
Cores U1602B-14H to 36F (138.2 to 241.98 mbsf) were split and described. The primary lithology is dark gray to very dark gray silty clay. Secondary lithologies include sand, clay with silt, and silty clay with nannofossils or biogenics. In Cores 14H to 26F, there are laminations, graded beds, and cross-bedding present at discrete intervals. A 1 m black sand bed is present in Core 22F. In Cores 26F to 36F, intervals of laminations are still present, but few graded beds and no cross-bedding are observed. These cores contain small, centimeter-scale silt layers that are predominantly composed of quartz. Clasts are observed between Cores 14H and 31F. Carbonate preservation varies throughout the section, and barren intervals are present.
Daily science report for 5 July 2023
Location:
- Hole U1602A (61°11.7138′N, 38°10.8186′W; 2708.6 m water depth)
- Hole U1602B (61°11.7144′N, 38°10.8184′W; 2709.2 m water depth)
Science Update: The day began with cutting off 105 ft of drill line, picking up the top drive, and spacing out the bit to initiate Hole U1602A. Core U1602A-1H recovered 8.8 m of core, establishing a seafloor depth of 2708.6 mbsl. However, Core 1H also recovered part of the “pig,” a foam device with metal bristles used to clean the inside of the drill pipe. Hole U1602A was terminated in order to recover an undisturbed mudline. Hole U1602B was spudded from the same ship position and Core U1602B-1H recovered 5.15 m of core with a good mudline. Coring continued from Cores 2H to 16H (5.2 to 147.7 mbsf). Temperature measurements using the APCT-3 were collected on Cores 4H, 7H, 10H, and 13H. Core 16H required 100,000 lb overpull to extract the core barrel from the sediment. The HLAPC was deployed for Cores 17F to 20F (147.7 to 166.5 mbsf). Core 18F had a partial stroke.
Throughout the day, 20 cores were collected over a 166.5 m interval, and 171.85 m of sediment was recovered (103%).
Cores U1602A-1H (0 to 8.81 mbsf) and U1602B-1H to 13H (0 to 119.66 mbsf) were split and described. The dominant lithology is silty clay. Minor lithologies include silty clay with biogenics or carbonate, sand, clay, and clay with silt and nannofossils. Laminated and cross-bedded intervals are observed as well as graded beds. Bioturbation is sparse throughout, and clasts are occasionally observed throughout the section. Carbonate components (foraminifers and nannofossils) are rare to barren. Methane concentrations are low, averaging ~2 ppm.
Daily science report for 4 July 2023
Location:
- In transit to proposed Site REYK-14B (Site U1602)
- Hole U1602A (61°11.7138′N, 38°10.8186′W; 2713.0 m preliminary water depth based on the precision depth recorder [PDR])
Science Update: The ship completed the 350 nmi transit to proposed Site REYK-14B (Site U1602) at 1701 h. At that time the thrusters were lowered, and the ship was in DP mode at 1718 h, marking the start of Site U1602. The remainder of the day was spent assembling the APC/XCB BHA and drill string.
Site U1602 was added to the Expedition 395 program following Expedition 395C in 2021. This site will core through the Eirik sediment drift on the eastern side of Greenland.
Cores U1562C-46F to 53F (262.8 to 300.73 mbsf) were split and described. These cores contain greenish gray to very dark gray silty clay, with or without biogenic and carbonate, and greenish gray nannofossil chalk. Soft sediment deformation is observed in Cores 49F to 53F.
The laboratory groups are working on reports for Expedition 395 Site U1554 and Expedition 395C Site U1563.
Daily science report for 3 July 2023
Location:
- Hole U1562C (60°6.3015′N, 26°30.0754′W; 2002.7 m water depth)
- In transit to proposed Site REYK-14B
Science Update: Cores U1562C-52F and 53F were recovered from 291.0 to 300.4 mbsf. After reaching the target depth of 300 mbsf, the drill pipe was pulled from the hole with the bit clearing the seafloor at 0405 h. The BHA was broken down and the rig secured for transit. At 0900 h the ship was switched from DP to cruise mode, ending Site U1562. The vessel began the 350 nmi transit to proposed Site REYK-14B, located within the Greenland exclusive economic zone. At the end of the day, the ship had completed 156.0 nmi at an average speed of 10.5 kt.
Cores U1562C-12H to 45F (91.8 to 263.13 mbsf) were split and described. Cores 12H to 16H are predominantly very dark gray silty clay with sparse to moderate bioturbation. The base of Core 16H contains several graded beds that are clayey silt with foraminifera. The sediment in Cores 17H to 32F is greener, with colors ranging from greenish gray to dark olive gray to black. The dominant lithology is silty clay with biogenics or carbonate. This interval contains sharp boundaries and graded beds. Beginning in Core 33F and extending to Core 43F, intervals of carbonate ooze with silty clay are interspersed between silty clay. Bioturbation is abundant in the carbonate-rich sediments. Core 42F contains nannofossil ooze and silty clay with biosilica. Cores 44F and 45F are greenish nannofossil oozes with silty clay and contain intervals of soft sediment deformation. Clasts are occasionally observed throughout the section. The base of Hole U1562C is late Miocene in age.
Daily science report for 2 July 2023
Location: Hole U1562C (60°6.3015′N, 26°30.0754′W; 2002.7 m water depth)
Science Update: Coring continued with the recovery of Cores U1562C-14H to 16H (110.8 to 139.3 mbsf). Core U1562C-16H had 100,000 lb overpull and required a drillover to free the core barrel. Refusal of the full-length APC system was reached and the HLAPC was deployed for the remainder of the hole. Cores U1562C-17F to 51F advanced the hole to 291.0 m. Four short drilled intervals (1.5 to 2 m in length) were used to offset coring gaps between Holes 395C-U1562A and 395-U1562C.
Cores U1554H-31H to 38X (280.1–354.8 mbsf) and U1562C-1H to 11H (0–92.4 mbsf) were split and described. Cores U1554H-31H to 38X contain very dark gray to black silty clay and the cores are biscuited. Cores U1562C-1H and 2H contain brown silty clay with varying amounts of biogenics, sand, and carbonate. Below these cores, the color varies between dark gray, very dark gray, black, and brown. The sediment is predominantly silty clay with absent to sparse bioturbation. The upper three cores contain graded beds and sharp contacts. Clasts are observed throughout. The cores recovered from Hole U1562C are recent to late Miocene in age.
Daily science report for 1 July 2023
Location:
- Hole U1554H (60°7.4952′N, 26°42.1188′W; 1866.7 m water depth)
- Hole U1562C (60°6.3015′N, 26°30.0754′W; 2002.7 m water depth)
Science Update: Coring continued with the recovery of Cores U1554H-33X to 38X (299.5 to 354.9 mbsf). After reaching the target depth for the hole, the drill string was pulled out of the hole. The drill bit cleared the seafloor at 0640 h, ending Hole U1554H. A total of 38 cores was recorded for Hole U1554H, with 370.1 m of core recovered across a 354.9 m interval (104%).
With the drill bit ~54 m above the seafloor, the vessel transited in dynamic position (DP) mode to Site U1562. Following a 6.1 nmi transit, the vessel was over the site coordinates at 1210 h, marking the start of Hole U1562C.
Site U1562 was visited on Expedition 395C in 2021. Two holes were cored; the first recovered the sedimentary section and the second targeted the basement basalts. Expedition 395 is revisiting Site U1562 to obtain a second copy of the sedimentary section down to ~300 mbsf.
Hole U1562C was spudded at 1500 h. The mudline Core U1562C-1H recovered 5.37 m, establishing a seafloor depth of 2002.7 mbsl. Cores U1562C-1H to 13H advanced the hole to 110.8 mbsf. One drilled interval of 1 m (U1562C-5-1) was used to offset coring gaps as observed by the stratigraphic correlators. All cores were oriented.
Cores U1554H-8H to 30H (61.6 to 280.44 mbsf) were split and described. These cores contain dark gray to black silty clay and silty clay with biogenics. Bioturbation is sparse to moderate. Clasts and shell fragments are observed. The cores are Pleistocene in age.