Technician: Alexander Roth

Scientists: Wout Krijgsman and Jiabo Liu

Portcall: Amsterdam to Napoli (December 11, 2023 - February 9, 2024)

Table of Contents

• 1 Summary
• 2 SRO Items
  • 2.1 Items shipped
  • 2.2 Items received
  • 2.3 Items ordered
• 3 Instruments
  • 3.1 Superconducting Rock Magnetometer (SRM)
  • 3.2 Haskris Water Chiller
  • 3.3 JR6 Spinner Magnetometer
  • 3.4 Magnetic Orientation Tools (MOTs)
  • 3.5 D-2000 AF demagnetizer
  • 3.6 MFK2 Kappabridge
  • 3.7 Thermal demagnetizer TD-48SC
  • 3.8 IM10-30 and IM-10 Impulse magnetizers

Open

^{AMS is cool.}

Summary

The BOX was a bit rough with major issues with the SRM Haskris system. After that was resolved (details below and on confluence), the expedition was very successful for the Pmag lab. The actual magnetostratography was difficult to interpret and all of the cased holes had severe inclines. However, this provided the opportunity to develop a new technique to resolve the bore-hole geometry from the lab's data. Also we used the magnetic orientation tools (MOTs) as they are designed to be used and conducted bore-hole surveys, both in real-time logging-in and out as well as reprocessing normal core-orientation data (without disrupting the normal core orientation protocol).   

Expedition 401 Material Measured (approximate)

SRO Items

Items shipped

None

Items received

None

Items ordered

None

Instruments

Superconducting Rock Magnetometer (SRM)

At the BOX, the SRM null-field was trapped and the profile was only  +/- 1nT in the SQUID region. The SRM AF Degauss coils were tested at 40 mT and all measured within spec to a few percent (see the SRM page for details).

The SRM was used extensively throughout the expedition for both discrete samples and archive SHLFs. The biggest issue was with flux jumps, since the samples were typically very weak. For the reason, the "Pause and Confirm" in the SRM IMS was vital. When an Outreach & Education tour was happening, they would give a 15 minute warning to us, and we would put the SRM in pause and confirm mode, and continue to measure. After each measurement, the data was inspected for flux jumps and immediately remeasured if there were issues. If (or once the data was clean), the next sequence was initiated. This allowed measurement to typically proceed with minimal interruption and no lost data due to flux jumps. The science party itself caused plenty of flux jumps and all SRM data was screened, inspected, and then deleted from LIMS (via LIME) when necessary adding hours of unnecessary work and data loss.

Haskris Water Chiller

The SRM Haskris chill water system was a disaster at the BOX: running the air-cooled Haskris most of the time and cleaning the wye-filter and heat-exchanger every few hours. A sediment sump and bypass system were installed and have been a game-changer. Arguably more important, was the SEIM crew re-installing the bag filters (AGAIN-other crew removes them?) on the chill water circuit. The system has been stable all expedition after the sump and bag filter installs except for a brief chill water interruption triggering the SRM alarms but not actually causing any issues (see the Hasrkis page for more details).

JR6 Spinner Magnetometer

The JR-6 was used extensively throughout the expedition. The manipulator was squealing at various points at the expedition. Silicon spray on the worm screw helped, but eventually the problem was diagnosed and fixed.

The spare JR6 was tested at the BOX and had belt issues. After resolving this, the unit still was having issues and will hopefully addressed before X402 BOX.

See the JR6 page for more details on both units.

Magnetic Orientation Tools (MOTs)

Icefield Tool 2043 was successfully passed all BOX tests including absolute orientation. As there is potential concern with the Flexit tools and explosives and the other Icefield MOTs being somewhere else in the world, tool 2043 was the only tool deployed the entire expedition. 

It was noticed (again), that batteries used in the MOTs can experience fast accelerations and decelerations and that this often causes physical damage to the battery and they no longer can maintain continual contact. Battery failure has commonly been reported with used MOT batteries used in other electronic devices and each time, they showed damage. This a much more realistic explanation for the tools dropping data and restarting memory during deployment, than the power harness coming off. For deployment this expedition, batteries were shrink wrapped as a unit and the battery spring was re-tensioned (stretched) to not allow them to slam around in the tool during core rejection (and/or partial-rejection).

2043 was using with the multi-shot protocol for U1609A. Initially the data was not super usefully for orientation, since the paleomag signal was weak and not well constrained. After lots of coffee and contemplation of the tools' use, it was determined that we can back out the bore-hole directional survey from the MOT data already collected. In fact this how the tool is designed to be used. This was done for U1609A and was going to be done again on U1610, but logging with the GPIT tool was scheduled, so it would have be redundant. And since our new SOP was experimental and thus risking OPs time, the tool was never deployed. Logging was unsuccessful and the hole geometry is presently being determined by AMS and Pmag.

We deployed the tool once U1611A casing was completed to conduct a basic test bore-hole survey (logging in) in the standard drill pipe and casing (both magnetic). The inclination/hole deviation data seem to be correct and around 10 °, but the magnetic data was likely deflected. 

The tool was again deployed as a "logging-out survey" near the bottom of U1611A. The pipe was rotating at ~17 RPM, so again the magnetic data was clearly deflected. The survey was done hastily to not impede on OPs time, and inclination data seems noisy as a result, though still reasonable. It seems likely that using the tool this way works for the hole deviation. If we deploy the MOT with the non-mag collar, then a full survey would be straight forward: get the APC survey during APC coring and orientation (MOT-MSP) and then deploy the tool again retrieving a core towards the EOH and log-out (assuming the non-mag collar is still in the BHA).

We deployed the tool again retrieving 64R on U1611B logging out as the first "real" bore-hole survey and this showed: 1) That the inclinations data seem correct. 2) The hole was near vertical (un-cased hole). 3) The tool showed a dip already in the first cores (1H-3H) when the drill pipe is still not in the formation and thus various currents are likely pushing the pipe. In fact the largest dip in on 2H and all 3 show 3x more variation in the azimuth than once in the hole. Once in the formation, the data is more vertical and stable. The rigid casing may tend to track the current influence more dramatically. 4) With a minor loss in OPs time, it is possible to deploy the Icefield MOTs and get the dip if logging is not scheduled or if it is likely that the hole will collapse or have impassable bridges.

For more details see the MOT page.

D-2000 AF demagnetizer

The internal field was again measured at the BOX and was consistent with that measured on previous expeditions (see the D-tech page for details). This was used extensively during the expedition to demagnetize discrete samples measured with the JR6. The computer crashed several times and I would not expect it to last much longer. But it wont have to...

MFK2 Kappabridge

The Kappabridge unit was used extensively during the expedition with the 3D and 3D on all Pmag discrete samples. The broken cube insert was installed at the EOX because it actually works for measuring samples wrapped in parafilm as they typically do not fit well into the insert.

Thermal demagnetizer TD-48SC

The oven was used briefly and no issues were noted. The internal field was again measured at the BOX and was consistent with that measured on previous expeditions (see the TD page for details).

IM10-30 and IM-10 Impulse magnetizers

Both units were used briefly at the BOX to give IRMs to the pmag playcubes. Coil number 3 is still in the IM-10-30 unit for up to 2.5 T for IRM acquisitions.