IODP Expedition 395C
Reykjanes Mantle Convection and Climate: Crustal Objectives
Daily Science Report for 5 August 2021
Location:
- Hole U1564C (59°51.0374′N, 23°16.0087′W; water depth 2208.1 mbsl; proposed Site REYK-2A)
- In transit to Reykjavík, Iceland
Science Update: The rig floor crew finished pulling up the drill pipe and the drill bit cleared the rotary table at 0100 h. The rig floor was secured for transit, the final thrusters raised, and the ship began the transit at 0106 h, ending Site U1564. At the end of the day, the vessel had completed 233 nmi of the 293 nmi transit to Reykjavík, Iceland.
The JRSO technical staff continued cleaning the laboratory spaces and prepared for the end of the expedition.
Expedition 395C ended with the first line ashore at 0842 h on August 6 in Skarfabakki harbor, Reykjavík, Iceland.
Daily Science Report for 4 August 2021
Location: Hole U1564C (59°51.0374′N, 23°16.0087′W; water depth 2208.1 mbsl; proposed Site REYK-2A)
Science Update: The crew continued pulling up the drill pipe until the bit was at 80.6 mbsf. The triple combo logging tool string was made up and at 0250 h the tool string was deployed. The triple combo descended to the bottom of the hole (628.9 mbsf) and made two passes of the borehole. The tool was recovered at 0930 h and broken down. The FMS-sonic tool string was made up, deployed to the base of the hole, and made a single pass imaging the borehole wall. The FMS-sonic tool was brought up to the rig floor at 1640 h and broken down. The downhole logging equipment was put away and the logging tools moved to the helideck. The rig floor crew began pulling up the pipe, with the bit clearing the seafloor at 1845 h. At 1920 h, four of the thrusters were raised and were secured at 2236 h. The day ended with the crew continuing to pull up the drill pipe and preparing the ship for transit.
The JRSO technical staff spent the day working on end-of-expedition activities and cleaning the laboratory spaces. The ship is schedule to arrive at the pilot station at 0700 h on 6 August.
Daily Science Report for 3 August 2021
Location: Hole U1564C (59°51.0374′N, 23°16.0087′W; water depth 2208.1 mbsl; proposed Site REYK-2A)
Science Update: Coring continued with Cores U1564C-66X to 75X advancing from 531.9 to 628.9 mbsf. A total of 618.71 m of core was recovered from Hole U1564C (98% recovery). Following Core 75X, the crew began pulling up the drill string in preparation for downhole logging operations using the triple combo tool.
Cores 66X to 75X are clay-rich sediments that alternate between gray, dark gray, and green in color. These cores have dark green, yellow, and dark gray mottling and are bioturbated. Methane concentrations decrease from 776 to 158 ppmv in these cores.
Daily Science Report for 2 August 2021
Location: Hole U1564C (59°51.0374′N, 23°16.0087′W; water depth 2208.1 mbsl; proposed Site REYK-2A)
Science Update: Coring continued with Cores U1564C-47X to 65X advancing from 347.6 to 531.9 mbsf. The core recovery for this interval was 94%.
Cores 47X to 56X contain dark gray clay to silt with occasional dropstones and shell fragments. Bioturbation is present in some intervals. Cores 57X to 65X are clay-rich sediments that alternate between light gray, greenish-gray, and dark gray in color. These cores have dark green, yellow, and dark gray mottling, bioturbation, and erosional surfaces. Methane concentrations range from 332 to 901 ppmv in these cores.
Daily Science Report for 1 August 2021
Location: Hole U1564C (59°51.0374′N, 23°16.0087′W; water depth 2208.1 mbsl; proposed Site REYK-2A)
Science Update: Coring continued with Cores U1564C-18F to 35F advancing from 159.0 to 243.6 mbsf. The overpull when retrieving Core 35F was over 80,000 lb and coring switched to the XCB system. Cores 36X to 46X were recovered from 243.6 to 347.6 mbsf.
Cores 18F to 46X are dark gray clay to silt. The XCB cores are disturbed from the coring process. Methane increases from 1.4 ppmv at 162 mbsf to a maximum of 1209 ppmv at 237.2 mbsf. Methane concentrations then vary between 513 to 1049 ppmv through Core 46X (340.9 mbsf).