IODP Expedition 400

NW Greenland Glaciated Margin

Daily science report for 31 August 2023

Location: Hole U1603D (72°59.0506′N, 62°58.8735′W; water depth 1800.8 m)

Science Update: We tripped the drill string up to 50.8 mbsf in preparation for logging. The quad combo tool string was rigged up and, following a repair to the logging winch, was deployed to the base of Hole U1603D (419.5 mbsf). The quad combo measures natural gamma ray (NGR), density, acoustic velocity, resistivity, magnetic susceptibility (MS), and density. Following a complete pass of the hole the quad combo was pulled to the rig floor and broken down. The Versatile Seismic Imager (VSI) was rigged up and the protected species watch began at 1600 h. The VSI was deployed but almost immediately experienced a communication issue. The tool was brought back onboard and repaired. At 1800 h the VSI was deployed to 413.1 mbsf and stations were measured up hole until 2120 h when fog impacted visibility and the ability to monitor for protected species. After the VSI tool was brought back onboard and broken down, the Formation MicroScanner (FMS)-sonic tool string was assembled and deployed at 2335 h.

Scientists worked on the reports for Site U1603.

Daily science report for 30 August 2023

Location: Hole U1603D (72°59.0506′N, 62°58.8735′W; water depth 1800.8 m)

Science Update: We began the day waiting on ice (WOI), positioned over Hole U1603D. At 0100 h we began preparing the subsea camera system to assist with reentering Hole U1603D. At 0320 h we successfully reentered the hole and recovered the subsea camera system. The drill string was lowered to 294.4 mbsf, and we washed down to 318.5 mbsf before encountering material that had fallen into the bottom of the hole. A center bit was dropped and the hole advanced to 333.2 mbsf by 0800 h. Cores U1603D-9R to 18R advanced from 333.2 to 422.0 mbsf and recovered 28.69 m (32%). Sepiolite (drilling mud) was swept into the hole and the bit was released at 2315 h to prepare for logging Hole U1603D.

Cores U1603D-9R to 18R were split and described. Cores 9R to 14R are composed primarily of gray and brown mud with some intervals of diamicton. Dispersed clasts are found throughout. Cores 15R to 18R are composed of gray mud, interlaminated mud and sand, and breccia. Soft sediment deformation is also present. Cores are barren or contain sparse fossils.

Daily science report for 29 August 2023

Location: Hole U1603D (72°59.0506′N, 62°58.8735′W; water depth 1800.8 m)

Science Update: We began the day waiting on ice (WOI). By 0015 h the ice had cleared the site. The drill string was lowered to 169.6 mbsf, and we washed back to 189.0 mbsf before drilling ahead to 269.4 mbsf. Cores U1603D-2R to 8R advanced from 269.4 to 333.2 mbsf and recovered 14.62 m (24%). At 1400 h ice moved within 3 nmi of the vessel and we raised the drill string to 22.3 mbsf by 1545 h and began WOI. Ice then entered the 1 nmi exclusion zone and we raised the drill string, clearing the seafloor at 1930 h. The vessel was moved 1000 m north to maintain a safe distance from the ice. By 2157 h we began to move back toward the site and the vessel was in position over Hole U1603D by 2348 h.

Cores U1603D-2R to 8R were split and described. The cores are composed primarily of gray diamicton and interlaminated mud and sand. Dispersed clasts are found throughout and intervals of calcareous mud are also present. Cores are barren or contain sparse fossils.

Daily science report for 28 August 2023

Locations:

Hole U1603C (72°59.0480′N, 62°58.8542′W; water depth 1800.8 m)
Hole U1603D (72°59.0506′N, 62°58.8735′W; water depth 1800.8 m)

Science Update: At 0000 h ice entered the 1 nmi exclusion zone. We raised the drill string, clearing the seafloor at 0009 h and ending Hole U1603C, and we began waiting on ice (WOI). The vessel was moved 1200 m east-northeast and then 700 m east-southeast to maintain a safe distance from the ice. By 0330 h the ice had cleared the site and the vessel was positioned 10 m northwest from Hole U1603C. Hole U1603D was spudded at 0455 h and, with a wash barrel, was drilled ahead to 102.0 mbsf. As ice once again neared the site, we decided to install a free-fall funnel (FFF) to allow us to reenter Hole U1603D. The FFF was deployed at 0950 h, and by 1030 h we resumed drilling ahead in Hole U1603D to 189.0 mbsf. At 1400 h ice moved within 3 nmi of the vessel and we raised the drill string to 22.3 mbsf by 1515 h and began WOI.

The laboratory teams continued measurements of discrete samples from Site U1603, such as carbonate, moisture and density (MAD), and paleomagnetic cubes. Scientists also worked on the reports for Site U1603.

COVID-19 mitigation procedures are no longer in place. The people rejoiced.

Daily science report for 27 August 2023

Location: Hole U1603C (72°59.0480′N, 62°58.8542′W; water depth 1800.8 m)

Science Update: A center bit was dropped and Hole U1603C was spudded at 0105 h. We drilled ahead in Hole U1603C to a depth of 211.5 mbsf. Cores U1603C-2R to 9R advanced from 211.5 to 285.0 mbsf and recovered 22.78 m (33%). At 1945 h ice moved within 3 nmi of the vessel and we raised the drill string to 22.3 mbsf and began waiting on ice (WOI).

Cores U1603C-2R to 9R were split and described. The cores are composed primarily of gray diamicton and interlaminated mud and sand. Dispersed clasts are found throughout and intervals of calcareous mud are also present. Palaeomagnetic measurements of Hole U1603B tentatively place the Brunhes–Matuyama reversal in Core U1603B-16F, consistent with sparse fossils identified in Hole U1603B.