Paleomagnetics Lab

Beth Novak and Nicolette Lawler

Scientists: Sara Satolli and Liang Yi

Summary

During Expedition 368X the SRM was used to measure archive section halves of predominately claystone, siltstone, and some sandstone.  Discrete specimens were measured in the JR6 magnetometer and demagnetized with the DTECH.  Discrete susceptibility measurements were completed on the Kappabridge Susceptibility meter.  

The low recovery allowed for time for cross training in the paleomagnetic lab with Nicolette and other maintenance activities.  The SRM was restarted after the Hong Kong floating dry dock without any issues.   After the Subic dry dock the SRM Cryomech compressors were swapped out and the adsorber in the spare compressor N2266 was replaced.  The IMS 10.2 SRM code was tested during the expedition and the manuals were updated.   After reported issues with the automatic sample holder during Exp 376, the JR6 spinners were thoroughly tested.   Both spinners are currently operational.  

Individual Measurement Systems

SRM

• The SRM was powered down due to dry dock activities in Hong Kong.  The system was restarted on November 15th and took approximately 30 hours to reach superconducting temperatures.  We did not do a manual field trapping because the ship was underway by the time the cool down was completed.  A field profile was measured and saved to the Pmag Documents folder on the Share drive.  

• The SRM was upgraded to IMS 10.2 during the dry dock period.  Thorough testing of IMS 10.2 was conducted through out the expedition.  The SRM User Guide and Quick Start guides were updated to reflect the changes to the software.  All software bugs were noted and the list will be passed on to Bill Mills.  Minor edits were made during Exp 368X to the SRM code to correct issues with file saving and track motion.  These code changes were checked into SVN.

JR6 Magnetometers

• JR6 #90769 was returned from AGICO after maintenance.  

• Testing was conducted on the JR6 #91063 to determine the cause of the E5 error that was reported during Exp 376.  When we began testing, the JR6 was still giving the E5 error with every "UP" command given from the Auxillary commands window.  AGICO suggested testing the optocouplers to ensure they were reading the correct voltages.  While following the instructions provided by AGICO for this procedure, two points of vibration were noted in the actuator assembly during "DOWN" motions.  The actuator screw assembly was removed, cleaned gently, and replaced.  After this cleaning procedure, the E5 error was not noted again.  

  • Both JR6 units gave the E5 error at the start of the expedition, but once #90769 was plugged into a different computer, the system ran normally.  It continued to function as expected when returned to the original computer.  The E5 error for this spinner may have been related to a software glitch.

• The JR6 #91063 screw assembly would get squeaky and need cleaning every 24 hours.  We noted some black dust near the screw, which is generally an indicator that the brass screw is wearing.  After discussing with AGICO, they suggested a VERY light drop of oil on the screw.  We applied Multi-Purpose Precision Lubricant (CRC) with a cotton swab.  Afterward the JR6 did not require the daily cleaning and the squeak was no longer noticeable.

• The reoccurring issue with the Rema6 software sample holder measurement was noted once during this expedition.   This error occurs when the Rema6 software says it has completed the holder measurement, but has only done one measurement position.  We have not found the cause of the issue, but it may be related to the holder not being in the proper initial position when the holder measurements begin.  When the error occurred, the actuator was found to be in the UP position but the holder was rotated to the wrong position.  The actuator could not make contact with the holder to rotate to position 2. This will need to be monitored further.

• JR6 #91063 had a serial communications issue at the start of the expedition while we were diagnosing the E5 error.  There may be a lose wire within the JR6, but once the system started communicating, we did not have the issue again.  

• The Rema6 software was reinstalled on the computer after differences in the software's behavior were noted.  The auxiliary command window was partially greyed out when opened. This is not typical.  After the reinstallation, the window had full functionality.

• AGICO is shipping a spare optocoupler to IODP based on the optocoupler test results.  Although both optocouplers are still working, one reads at a voltage of 3.7 V rather than 5 V.  They will also be shipping a spare actuator screw and base plastic pieces for securing the actuator screw.  Items should arrive on the ship for Exp 379.

Cryomech Compressor

• The compressors were swapped out during the tie-up and have been tagged with blue IODP tags.  

• Compressor N2266 was the original compressor running with the SRM from December 2016 to October 2018.

• Compressor N2267 is currently running with the SRM.

• The adsorber was replaced in N2266 to make this a working spare.

  • During the replacement a small bit of oil was noticed on the Aeroquip coupling and the coupling was covered in surface corrosion.  After contacting Cryomech we determined that the corrosion is likely caused by our chill water being too cold and causing condensation to form on the couplings.  The coupling can be replaced, but the compressor must be vented of helium first. We opted to simply clean the corrosion off of the connector since it was all surface corrosion.  Cryomech provided venting instructions which have been saved to the JR Laboratories Paleomagnetic page on Confluence.

  • The light oil film on the Aeroquip connectors was not an issue.  Cryomech indicated that if oil were to pour out of the Aeroquip when it is removed from the adsorber, then there would be cause for concern.  We vented the pressure from  adsorber and checked for any oil.  There was only a light film within the adsorber, which is expected.

• CryoWATCH was not operating during the expedition.  As a replacement for monitoring the compressor temperatures and pressures, we used the Cryomech logging software.

Kappabridge Magnetic Susceptibility Meter

• No issues were reported with the Kappabridge hardware

• The Sufar.exe program was used for specimen measurements. As usual, we lost the last few lines of each day of measurements.  This behavior is a known issue and can only be avoided if a blank measurement is triggered at the end of a set of measurements.

• The Kappabridge data was not uploaded due to an error with the uploader.  An 'unhandled exception' window appeared as soon as an upload was triggered with MUT.  This error may be related to sample naming.  The samples were not originally named with their Text IDs.  The .asc files were edited to correct this issue, but we were not able to fix the .ran files.  The data was transferred to Data 1.

• Testing continued on the updated version of AMSspin.  The final version will allow us to upload a .csv file and will help avoid the current file writing issues experienced with Sufar.exe.

D2000 A.F. Demagnetizer (DTECH)

• No issues reported with the DTECH

Orientation Tools

• Orientation tools were not used during Exp 368X

General

• Scientists reported an error that occurs when using Puffin Plot.

  • Puffin plot occasionally produces incorrect values for declination and inclination.  In one example, all of the data are positive inclination, but the resulting PCA answer is negative inclination.  The figure below shows the same data set as plotted by Puffin Plot and by Paleomac.  The results differ significantly.  The scientists also noted that when the first point of the data are removed, Puffin plots PCA is more similar to the Paleomac answer.  We need to make our scientists aware of these possible errors and possibly evaluate the continued use of Puffin Plot.

   

  Open

  

• Scientists requested that LIVE have a zero line for the inclination and declination plots.