IODP Expedition 403

Eastern Fram Strait Paleo-Archive

Daily science report for 30 June 2024

Location:

Hole U1620A (78°16.3087′N, 5°53.3789′E; water depth 1577.7 m)
Hole U1620B (78°16.3566′N, 5°53.8548′E; water depth 1597.1 m)

Science Update: Cores U1620A-17X to 31X were retrieved from 133.9 to 239.9 mbsf, the final depth of the hole. All of the cores expanded due to high gas concentrations. Thus, the cores were advanced by 6 to 8 m, depending on the expansion of the previous cores. Formation temperature measurements were collected with the SET2 tool after Cores U1619A-18X and 31X at 145.9 and 239.9 mbsf, respectively. Headspace gas C₁/C₂ ratios were being monitored for safety. Gas values for several consecutive cores plotted at the perimeter of our safety envelope, thus the decision was made to end the hole. Hole U1620A reached a maximum penetration of 239.9 mbsf and recovered 277.1 m of sediments (116% recovery). The drill string was pulled up, the bit cleared the seafloor at 2025 h, and the vessel was moved 200 m to the northeast along Seismic Line Svyatogor2014_3D_XL222 at 2050 h. After minor maintenance on the core winch line, the first attempt to spud the hole at 1582.5 mbsl recovered an empty barrel. The bit was lowered to 1589.5 mbsl and Hole U1620B was spudded at 2327 h. The mudline of Core U1620B-1H and the recovered sediment of 0.4 m were insufficient, so preparations were made to spud Hole U1620C shortly after midnight.

Cores U1620A-14H to 31X were run through the whole-round physical properties track systems, and Cores U1620A-7H to 24X were split and described. The cores predominantly consist of alternating dark gray silty clay and clayey mud, to firmer, dark gray silty clay toward the end of the described interval. Most cores are structureless but contain dispersed to common clasts (IRD).

Daily science report for 29 June 2024

Location:

In transit to proposed Site SVR-03A (Site U1620)
Hole U1620A (78°16.3087′N, 5°53.3789′E; water depth 1577.7 m)

Science Update: The vessel completed the final 26 nmi of transit and arrived at Site U1620 (proposed Site SVR-03A), lowered the thrusters, and was under DP control by 0256 h. An APC/XCB BHA was rigged up and lowered to the seafloor. Hole U1620A was spudded at 0820 h. Core U1620A-1H recovered a good mudline and 0.74 m of sediment, placing the seafloor depth at 1577.7 mbsl. Cores U1620A-1H to 16X were retrieved from 0 to 133.9 mbsf. Formation temperature measurements were collected with the APCT-3 tool on Cores U1620A-4H, 7H, 10H, and 13H. All of the cores expanded due to high gas concentrations. Thus, Cores U1520A-15X and 16X were advanced by 4.8 m and 5.5 m, respectively, to allow for gas expansion. Headspace gas C₁/C₂ ratios are being monitored for safety.

Cores U1620A-1H to 13H were run through the whole-round physical properties track systems, and Cores U1619A-82X to 85X and Cores U1620A-1H to 6H were split and described. Cores U1619A-82X to 85X consist predominantly of firm silty clay with dispersed clasts and minor traces of bioturbation. Cores U1620A-1H to 6H consist of alternating intervals of greenish gray silty clay and sandy mud with dispersed to common clasts.

Daily science report for 28 June 2024

Location:

Hole U1619A (79°9.5894′N, 4°29.3227′E; water depth 1676.1 m)
In transit to proposed Site SVR-03A (Site U1620)

Science Update: Cores U1619A-80X to 85X were retrieved from 579.1 to 627.9 mbsf, the final depth of the hole. To allow for core expansion, XCB cores were advanced by 8 m through Core U1619A-83X, with full advances thereafter. Over night, the MIZ reached the vessel and the ice edge was ~8 nmi from the site. Before noon, it became clear that the prevailing winds would continue to push the ice toward us from the northwest and southwest. Thus, a FFF was assembled and deployed at 1245 h, and the pipe was tripped out of the hole. The bit cleared the seafloor at 1505 h and the rig floor at 1940 h. While tripping the pipe, the beacon was released from the seafloor at 1536 h, and it was recovered shortly after at 1600 h. The vessel was switched from DP mode to cruise mode, ending Hole U1619A and Site U1619. The vessel was secured and was underway to proposed Site SVR-03A (Site U1620) at 2012 h. At the end of the day, the vessel had traveled 36.8 nmi of the 62.8 nmi transit at an average speed of 9.9 kt. Hole U1619A reached a maximum penetration of 627.9 mbsf and recovered 728.35 m of core (116% recovery).

Cores U1619A-77X to 85X were run through the whole-round physical properties track systems, and Cores U1619A-65X to 81X were split and described. The cores predominantly consist of firm, mostly structureless silty clay with isolated layers of sandy mud. Dispersed clasts are present, but less common than higher up in the hole.

Daily science report for 27 June 2024

Location: Hole U1619A (79°9.5894′N, 4°29.3227′E; water depth 1676.1 m)

Science Update: Cores U1619A-68X to 79X were retrieved from 488.6 to 579.1 mbsf. To allow for core expansion, all XCB cores were advanced by 7.5 m. Headspace gas C₁/C₂ ratios are being monitored for safety. The MIZ is currently 3–4 nmi away from the site, with the consolidated ice 15 nmi off the vessel. Depending on the predominant wind direction, the vessel is projected to be in the MIZ by morning, though ice is not expected to be present in the part of the MIZ heading toward us. The ice situation is permanently monitored and regularly reported by our two Ice Navigators. Additional crew members complement the Ice Navigator’s watch, so that permanent surveillance is ensured. All measures are in place to trip out of the hole and drop a FFF if ice approaches our safety perimeter.

Cores U1619A-65X to 76X were run through the whole-round physical properties track systems, and Cores 47X to 64X were split and described. The cores predominantly consist of firm, dark gray silty clay and clayey silt. Several sections contain silt- to sand-sized dark grains that seem to interfere with our magnetic susceptibility (MS) and paleomagnetic measurements, and are tentatively interpreted as greigite. All cores contain IRD clasts.

Daily science report for 26 June 2024

Location: Hole U1619A (79°9.5894′N, 4°29.3227′E; water depth 1676.1 m)

Science Update: Cores U1619A-53X to 67X were retrieved from 375.1 to 488.6 mbsf. To allow for core expansion, all XCB cores were advanced by 7.5 m. Headspace gas C₁/C₂ ratios are being monitored for safety. The Marginal Ice Zone (MIZ) is currently 3–6 nmi, and consolidated ice is 13 nmi away from the vessel. Depending on the predominant wind direction, the ice might close in further, forcing the vessel to move out of the way. Thus, we decided to stage a free-fall funnel (FFF) and we are ready to deploy it if necessary. The ice situation is permanently monitored and regularly reported by our two Ice Navigators.

Cores U1619A-49X to 64X were run through the whole-round physical properties track systems. Cores U1619A-34X to 46X were split and described. Core U1619A-56X was split out of order for sedaDNA sampling and subsequently described. The cores predominantly consist of dark gray silty clay and clayey silt. The upper part of the described interval contains several patches of biosiliceous-bearing silty clay that disappear downhole. Larger IRD clasts (>1 cm) remain less common than at Site U1618, but are found in every core. Starting at Core 46X, and including the out-of-order Core 56X, the sediments become significantly firmer. The first drafts of Site U1618 chapters were submitted and are currently under review by the Science Office.

Daily science report for 25 June 2024

Location: Hole U1619A (79°9.5894′N, 4°29.3227′E; water depth 1676.1 m)

Science Update: Cores U1619A-31X to 52X were retrieved from 210.1 to 375.1 mbsf. Formation temperature measurements were collected with the SET2 tool after Core U1619A-44X at 315.1 mbsf. To allow for core expansion, all XCB cores were advanced by 7.5 m. Headspace gas C₁/C₂ ratios are being monitored for safety.

Cores U1619A-28X to 48X were run through the whole-round physical properties track systems. Cores U1619A-16F to 33X were split and described. The cores predominantly consist of alternating gray silty clay and clayey silt. Several sections in the upper half of the described interval show stronger signs of bioturbation. Larger IRD clasts (>1 cm) remain less common than at Site U1618, but are found in every core. Cores U1619A-31X to 33X consist of firm silty clay and show more pronounced signs of biscuiting than the cores above. The science party met in the conference room to discuss their main findings and observations of Site U1618. All laboratory groups are working on their Site U1618 reports.

Daily science report for 24 June 2024

Location: Hole U1619A (79°9.5894′N, 4°29.3227′E; water depth 1676.1 m)

Science Update: Cores U1619A-3H to 30X were retrieved from 12.9 to 210.1 mbsf. Formation temperature measurements were collected with the advanced piston corer temperature (APCT-3) tool on Cores U1619A-4H, 7H, 10H, and 13F, and with the SET2 tool after 28X at 197.0 mbsf. To allow for core expansion, all XCB cores were advanced by 7.5 m. Headspace gas C₁/C₂ ratios are being closely monitored for safety.

Cores U1619A-1H to 27X were run through the whole-round physical properties track systems. Cores U1619A-1H to 15F were split and described. The cores predominantly consist of alternating gray silty clay and clayey silt with some green and yellow layers. Dispersed clasts and sandy layers are common throughout the cores, but larger IRD clasts are less common than in Site U1618. All laboratory groups are working on their Site U1618 reports and overview slides for the site results meeting.

Daily science report for 23 June 2024

Location:

Hole U1618C (78°56.8960′N, 7°28.4368′E; water depth 1195.8 m)
Hole U1619A (79°9.5894′N, 4°29.3227′E; water depth 1676.1 m)

Science Update: Cores U1618C-60X to 62X were retrieved from 392.1 to 413.1 mbsf, the final depth for the hole. Some of our XCB cores expanded upon recovery. The decision to advance by 7 to 7.5 m to allow for core expansion was kept in place. The C₁/C₂ ratios for Cores U1618C-61X and 62X plotted outside of our safety envelope, thus the decision was made to end the hole. Hole U1618C reached a maximum penetration of 413.1 mbsf with a cored interval of 411.1 m and a recovery of 450.59 m (110% recovery). The pipe was pulled from the hole with the bit clearing the rig floor at 1120 h. While pulling the pipe, the beacon was recovered at 0945 h. The rig floor was secured for transit, the vessel was switched from DP mode to cruise mode, and we were underway to proposed Site VRW-03A (Site U1619) at 1151 h. The vessel arrived at proposed Site VRW-03A (Site U1619) at 1512 h and was switched to DP mode, and we started making up the APC BHA at 1545 h. The beacon was deployed at 1646 h. Hole U1619A was spudded at 2219 h. Core U1619A-1H recovered a good mudline and 3.39 m of sediment, placing the seafloor depth at 1676.1 mbsl. Cores U1619A-1H to 2H were retrieved from 0 to 12.9 mbsf.

Cores U1618C-57X to 62X were run through the whole-round physical properties track systems. Cores U1618C-47X to 62X were split and described. The cores predominantly consist of alternating silty clay and clayey silt, with some layers of clayey sand. Most cores contain clasts of IRD.

Daily science report for 22 June 2024

Location: Hole U1618C (78°56.8960′N, 7°28.4368′E; water depth 1195.8 m)

Science Update: Cores U1618C-42X to 59X were retrieved from 267.1 to 392.1 mbsf. Some of our XCB cores expanded upon recovery. The decision to advance by 7 to 7.5 m to allow for core expansion was kept in place. Headspace gas C₁/C₂ ratios are being closely monitored for safety.

Cores U1618C-38X to 56X were run through the whole-round physical properties track systems. Cores U1618C-26X to 46X were split and described. The cores consist of alternating layers of silty clay and clay. In several cores we observed isolated layers of sand and gravel that might be indicative of paleo-glacial melting events. The lower half of the interval described today shows an increase in IRD.

Daily science report for 21 June 2024

Location: Hole U1618C (78°56.8960′N, 7°28.4368′E; water depth 1195.8 m)

Science Update: Cores U1618C-18H to 41X were retrieved from 114.6 to 267.1 mbsf. Some of the extended core barrel (XCB) cores expanded upon recovery. Thus, we decided to advance by ~7 m to allow for core expansion. Headspace gas C₁/C₂ ratios are being closely monitored for safety.

Cores U1618C-12H to 37X were run through the whole-round physical properties track systems. Cores U1618C-3H to 25X were split and described. The cores consist of alternating layers of silty clay and clay. In several cores we observed isolated layers of sand and gravel that might be indicative of paleo-glacial melting events. IRD was present in most cores.

Daily science report for 20 June 2024

Location:

Hole U1618B (78°56.8855′N, 7°28.4818′E; water depth 1195.2 m)
Hole U1618C (78°56.8960′N, 7°28.4368′E; water depth 1195.8 m)

Science Update: Logging with the FMS-sonic tool string continued until 0300 h. The Versatile Seismic Imager (VSI) tool was rigged up and deployed; however, an electronic failure in the tool led to a loss of the Z-axis signal, rendering the tool unusable. The VSI was recovered and a second VSI tool was rigged up. This tool experienced an electronics failure and was unable to be deployed. Thus, the VSI logging run was cancelled and the pipe was pulled from the hole with the bit clearing the seafloor at 0740 h, ending Hole U1618B. The vessel was moved 25 m northwest along Seismic Line CAGE20-5-HH-02-2D. Hole U1618C was spudded at 1012 h. Core U1618C-1H recovered a good mudline and 1.45 m of sediment, placing the seafloor depth at 1195.8 mbsl. Cores U1618C-1H to 17F were retrieved from 0 to 114.6 mbsf. For correlation purposes, operations included one drilled interval (161) between 107.9 and 109.9 mbsf.

Cores U1618C-1H to 11H were run through the whole-round physical properties track systems. Cores U1618C-1H to 3H were split and sampled for sedaDNA analyses, and Cores U1618C-1H and 2H were described. The cores consist of structureless clayey silt and silty clay. Both cores contain dispersed to common IRD clasts.

Daily science report for 19 June 2024

Location: Hole U1618B (78°56.8855′N, 7°28.4818′E; water depth 1195.2 m)

Science Update: Cores U1618B-47X to 54X were retrieved from 365.3 to 414.3 mbsf, the final depth of the hole. Formation temperature measurements were collected with the SET2 tool at 401.5 mbsf. Headspace gas measurements indicated anomalous C₁/C₂ gas ratios, outside of the safety envelope, and Hole U1618B was ended. Hole U1618B reached a maximum penetration of 414.3 mbsf with a cored interval of 414.3 m and a recovery of 375.24 m (91% recovery). In preparation for downhole logging, the pipe was pulled from the hole with the bit positioned at a depth of 79.6 mbsf. The triple combo tool string was rigged up by the Schlumberger Engineer and was deployed at 1645 h. Two successful passes of the triple combo reached a depth of 373.3 and 368.3 mbsf, indicating some fill-in in the bottom of the hole. Following the triple combo, the Formation MicroScanner (FMS)-sonic tool string was rigged up and deployed at 2215 h.

Cores U1618B-44X to 54X were run through the whole-round physical properties track systems, and Cores U1618B-39X to 54X were split and described. The cores consist predominantly of gray clay and dark gray silty clay. The sediments are generally structureless and show no prominent signs of bioturbation. The lower half of the interval described today shows an increase in ice-rafted debris (IRD). Foraminifers, nannofossils, and dinocysts are present; all samples remain barren of diatoms.

Daily science report for 18 June 2024

Location: Hole U1618B (78°56.8855′N, 7°28.4818′E; water depth 1195.2 m)

Science Update: Cores U1618B-28X to 47X were retrieved from 219.7 to 365.3 mbsf. As some of our cores still expand upon recovery, yesterday’s decision to shorten the advances to ~7 m to allow for core expansion was kept in place. Formation temperature measurements were collected with the SET2 tool after Core U1618B-41X at 325 mbsf. A previous deployment after Core 40X did not yield a temperature reading. Headspace gas C₁/C₂ ratios are being closely monitored for safety.

Cores U1618B-24X to 43X were run through the whole-round physical properties track systems, and Cores U1618B-13H to 38X were split and described. The cores consist predominantly of dark gray silty clay and structureless dark gray clay. In several cores we observe isolated layers of normally graded sandy silt. Isolated rocks (ice-rafted debris) are present in most cores. The clasts, preliminary identified as coal yesterday, are more common, and upon closer inspection are identified as authigenic Fe-sulfides that interfere with paleomagnetic measurements. X-ray diffraction (XRD) analysis on these clasts is still in progress. Good age markers for foraminifers, nannofossils, and dinocysts are present; all samples remain barren of diatoms.

Daily science report for 17 June 2024

Location: Hole U1618B (78°56.8855′N, 7°28.4818′E; water depth 1195.2 m)

Science Update: Cores U1618B-14F to 27X were retrieved from 112.8 to 219.7 mbsf. As some of our cores expanded upon recovery, we decided to shorten the advances to ~7 m beginning at Core U1618B-18X to allow for expansion in the empty space of the core liners, thus reducing the risk of losing sediment. Following Cores U1618B-20X, 25X, and 26X, the bit deplugger tool was deployed. Headspace gas C₁/C₂ ratios are being closely monitored for safety.

Cores U1618B-13H to 23X were run through the whole-round physical properties track systems, and Cores U1618A-32X to 37X and U1618B-1H to 12H were split and described. The cores consist predominantly of clayey silt and silty clay. In several cores we observe isolated layers of sand that might be indicative of paleo-glacial melting events. Isolated rocks (ice-rafted debris) are present in most cores. One core contains clasts that are tentatively identified as coal by visual inspection.

Daily science report for 16 June 2024

Location:

Hole U1618A (78°56.9070′N, 7°28.3866′E; water depth 1196.0 m)
Hole U1618B (78°56.8855′N, 7°28.4818′E; water depth 1195.2 m)

Science Update: Cores U1618A-33X to 37X were retrieved from 228.3 to 276.9 mbsf, the final depth of the hole. Formation temperature measurements were collected with the Sediment Temperature 2 (SET2) tool at 249 mbsf. Headspace gas measurements indicated anomalous C₁/C₂ gas ratios, outside of the safety envelope. The pipe was pulled from the hole with the bit clearing the seafloor at 1043 h, ending Hole U1618A. Hole U1618A reached a maximum penetration of 276.9 mbsf with a cored interval of 276.9 m and a recovery of 252.62 m (91% recovery). The vessel was moved 50 m southeast along Seismic Line CAGE20-5-HH-02-2D. Hole U1618B was spudded at 1245 h. Core U1618B-1H recovered a good mudline and 2.82 m of sediment, placing the seafloor depth at 1195.2 mbsl. Cores U1618B-1H to 13H were retrieved from 0 to 112.8 mbsf. On the catwalk, several cores showed signs of core expansion due to the presence of methane, however it was less pronounced than in cores recovered from Hole U1618A. The average recovery was 99%, ranging between 87% and 107%.

Cores U1618A-32X to 37X and U1618B-1H to 12H were run through the whole-round physical properties track systems, and Cores U1618A-13F to 31X were split and described. The cores consist predominantly of clayey silt and silty clay. In several cores we observed isolated layers of sand that might be indicative of paleo-glacial melting events. Isolated rocks (ice-rafted debris) were present in most cores.

Daily science report for 15 June 2024

Location: Hole U1618A (78°56.9070′N, 7°28.3866′E; water depth 1196.0 m)

Science Update: Cores U1618A-4H to 32X were retrieved from 23.9 to 228.3 mbsf. On the core receiving platform (catwalk), several cores showed signs of core expansion due to the presence of methane. The average recovery was 95%, ranging between 28% and 159%. Formation temperature measurements were collected during Cores 4H, 7H, 10H, and 13F.

Cores U1618A-1H to 31X were run through the whole-round physical properties track systems, and Cores U1618A-1H to 12F were split and described. The cores consist predominantly of mud, with alternating percentages of silt and clay. In several cores we observed isolated layers of sand and gravel that might be indicative of paleo-glacial melting events. Isolated rocks (ice-rafted debris) were present in most cores.

Daily science report for 14 June 2024

Location:

Underway to proposed Site VRE-03 (Site U1618)
Site U1618 (78°56.9070′N, 7°28.3866′E; water depth 1196.0 m)

Science Update: The vessel arrived at Site U1618 at 0859 h, lowered the thrusters, and switched to dynamic positioning (DP) mode at 0919 h. As GPS coverage in the high Arctic is sparser than in lower latitudes, we deployed an acoustic location beacon to ensure precise positioning, even if it meant temporarily losing satellite connections. A bottom-hole assembly (BHA) for the advanced piston corer (APC) was made up and deployed at 1400 h. Following maintenance on the core winch line, the first core was shot at 1186.8 meters below sea level (mbsl). Without accurate water column models (i.e., salinity or temperature), our depth sounding was off, and the core yielded zero recovery. The BHA was lowered by 5 m, and Hole U1618A was spudded at a depth of 1196.0 mbsl at 2225 h. Core U1618A-1H had a total recovery of 4.88 m and a good mudline. Cores U1618A-1H to 3H advanced to 23.8 meters below seafloor (mbsf) with 103% recovery. All cores yield high methane concentrations and expanded upon recovery.