Exp 403 Core Lab Report

Technicians: River Rivera & Jesse Yeon

Portcall: Amsterdam, Netherlands to Amsterdam, Netherlands (2 June 2024 – 2 August 2024)

Summary:

The core lab was fully stocked with supplies and tools at the start of Expedition 403, ensuring a smooth workflow. Cores were recovered, sampled, and labeled using the IODP standard. The cores underwent physical properties testing, including magnetic susceptibility, density, P-wave velocity, and gamma radiation measurements. After splitting, scientists sampled and described the core sections, which were then stored in D-tubes for offloading at the end of the expedition. No critical issues arose during the expedition, with only minor troubleshooting and repairs required to complete objectives. Small issues denoted below.

Core Lab Status of The Catwalk:

Catwalk - Catwalk procedures were normal for the most part and not necessarily out of the norm. Additional supplies were placed in the catwalk in case of unusual circumstances. Such instances denoted below:
- Unusual circumstances:

1. 1. Exploding core liners - Due to high gas content within some void spaces inside the core liners, precaution is required before operating normal catwalk procedures, in order to prevent explosion and subsequent shrapnel of plastic shards and mud. To protect marine technicians while carrying the core onto the catwalk, kevlar blankets were utilized. Holes were drilled in the liner, typically in void spaces. This is to decrease pressure within the core liners before cutting commenced. The drill crew added holes to some liners before dropping them for XCB cores in hopes the pressure would dissipate before arriving on deck. A few instances of the core liner shattering on the catwalk occurred during the cutting process. Hearing protection may be required for future reference as the shockwave could be felt during explosion and cause slight hearing loss. Another useful reference could be reviewing the gas content on LORE. Higher methane, but also other gas contents such as propane, hexane, lowering of the C1C2 ratio, etc, being present could reflect if additional practices are required before cutting. Such as wearing hearing protection beforehand, use of kevlar blankets, and drilling additional holes in the liner itself before cutting.
  2. Broken core liners - If core liners were broken/shattered due to unforeseen circumstances such as implosion within the drill pipes or rapid expansion and explosion of core liner in the drill pipes, explosion of core liner on the catwalk, etc, typical repairs involved patching up simple cracks with liner patches, or replacing the liner by removing sediment into new core liners. Afterwards, these were sonic welded to prevent the repairs from prematurely fall off.
  3. Sediment expansion - Cores with high gas content and at rather shallow locations (~cores 6-15) had problems with expansion within the liner, where, as soon as the core is on deck, sediment on the bottom end of the core starts to extrude out rapidly. Typically these were cut off and added to the core catcher if this occurred at the bottom of the core. Sediment would expand rapidly after sections were cut. This resulted in technicians adding extender caps on both the top and bottoms of the core sections, to ensure the capture of all expanded core within one section. To stay ahead of the game, extra extenders were pre-made prior to a new site/hole, having about ~20 extenders of blue and grey caps at all times to account for these issues. Measurement of the cores were also shorter than the norm, to account for the expansion. As a final act, the extenders were also sonic welded.
  4. MBIO Catwalk sampling - aDNA samples were pre-defined with SAC. Detail sampling procedure is described in Chemistry/MBIO lab tech report.

System Status of Core Lab Equipment:

The Core lab's computers received Windows software updates, which briefly caused instrument errors, but were quickly resolved.

Laser Engraver:

The air flow sensor on the laser encountered a few issues during the expedition, but was resolved with cleaning on most occasions. The air flow sensor sensitivity was adjusted to ensure the sensor was registering air flow properly. At Site 1618, the exhaust fan failed, causing the laser to retain smoke, but once the fan was repaired and the sensitivity of the sensor adjusted, the laser functioned normally. Common human errors with the laser engraver involved improper closure of the door mechanism, leading to the laser software giving an error. Simply closing the door again to ensure it was latched would clear the error.

Splitting Room, Wire/Hook Blades:

The Wire/Hook Blades splitter functioned successfully with minor issues. The hook blades would break occasionally due to core liner extenders, and new blades were inserted as needed. The wire portion would sometimes get caught and snap due to hard rock in sediment cores, but the tool could be reset and continued use after checking for damage. One common reason for hook blade breakage was due to liner patches and extender caps that can nearly double the thickness of the core liner. This results in the hook blades having issues "catching" the liner properly, causing deformation and eventually breaking the hook blades. One type of fix for this was to install the hook blades more inwards, so that the liner catches the base of the of hook blade and lets it ride up to the tip, so the full liner can be cut. During MBIO sampling, the splitting tool was cleaned between each core section using bleach, DI water, and Ethanol to prevent contamination. The splitting room was also sanitized as much as possible, and personnel wore protective gear to minimize contamination risks.

We encountered issues with sections with extenders on both ends being cut unevenly and the working half would not fit back in the dtube. One method used to solve this issue was rolling the core over and re-splitting the section. This did require the liner around the core to be completely replaced.

Splitting Room, sample saw:

The rock saws were used to split hard rocks in sediment cores when encountered during wire/hook blade splitting, ensuring both working and archive halves received approximately half of the stone. The saw functioned without any issues throughout the expedition.

Splitting Room, Core Splitting Saw (Super Saw):

The Super Saw functioned correctly. There were not many new blades available so a variety of previously used blades were used throughout the expedition. For MBIO sampling, the saw was cleaned and operated with ship water, which was also taken as a control sample for U1618C 62X2.

Ultrasonic welder:

The ultrasonic welder functioned correctly throughout the expedition and was used heavily to secure liner patch and extender caps.

Pneumatic Stapler and Dremel:

The Pneumatic Staplers and Dremel tool functioned correctly most of the time, with some minor issues. The staplers occasionally jammed in the Core lab and Splitting Room, requiring repair by the on-shift engineer. The Dremel short-circuited once but was resolved by resetting the GFCI outlet. Additionally, there was a one-time issue where the Dremel wouldn't run even with power but was resolved by adjusting the speed setting; however, no permanent fix was implemented for this issue.

Zebra Label Printers:

The Zebra label printers functioned correctly most of the time, with some minor issues. The Core entry printer was replaced mid-expedition due to issues with label feeding. Other printers required occasional troubleshooting for stuck labels or offset changes caused by improper label tearing.

Items Received:

None, fully stocked before expedition during tie-up.

Items Ordered:

None, end of program. Any necessary equipment is most likely provided by the incoming demob team.

Critical Maintenance:

None, however, small scale maintenance may be required on the core cutters, as most of the cutters had a slight offset during the cutting process resulting in misaligned cut lines on the liner.