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Standard Operating Procedure - Paleomagnetism Lab

March 2018
The Paleomagnetics Lab technician shares his/her duties between the Core Lab and the Paleomagnetics Lab. For details on the Core Lab duties, refer to the Core Lab SOP.

I. PRE EXPEDITION

  • See General JRSO Shipboard Technical Staff SOP

II. PORT CALL - Start of an Expedition

Cryogenic Magnetometer

  • Check the vital signs of the Cryogenic Magnetometer. Use the electronics interfaces to measure the vital signs inside the magnetometer: SQUID temperature and shield temperature. Record the values on the log sheet.
  • Check water level and condition inside the Haskris. Check the CryoWATCH software to monitor the compressor oil and water temperatures. Create a new log file for the expedition. For more detailed instructions refer to the SRM user guide.
  • If a service call is scheduled, make sure you prepare all supplies necessary for it. Find the service representative.


Other task

  • Measure the interior field of the magnetometer using the 3-axis fluxgate ("field profile"). Use the DAFI utility in the IMS-SRM software. Save the excel file to IODP Share: Pmag_Documents: SRM: Field Profiles. Each file should be labeled with the date of measurement.
  • If it is necessary to heat the SQUIDs to release a trapped field, follow the field trapping procedure in the user guide.
  • Check the field produced by the degauss coils within the SRM using the axial and transverse Hall probes
  • Introduce scientists to the cryomagnetometer and run basic measurements, such as:
    • Clean the tray and demagnetize at a field of 30 mT or higher and measure the tray. Measure the tray as a fake sample and compare results to ensure corrections are done properly. This should be done with the section half and, if applicable, the discrete tray.
    • Conduct positioning tests along the track with a section half tray. Testing should be done with an empty, light tray and a weighted, heavy tray. Check discrete boat positioning as well.
    • Measure a split core or play core.
  • Check to see if any regular maintenance projects need to be completed. Specifically check if the adsorber in the Cryomech compressor is due for replacement. If the bi-annual replacement of the adsorber is required, swap the entire Cryomech compressor with the spare compressor. Record the date of the change (place sticker on compressor).
  • Provide safety tour to all scientists who work in the Paleomagnetic lab area. Ensure all scientists understand the safety concern and sign  document required

III. SITE PREPARATION - Prior to arrival on site and core on deck

The following is a list of actions that should be accomplished prior to arriving at the first site. On cruises with short transit times before reaching the first site it is advisable to perform as many of the preparations in port as possible.
Paleomagnetics Lab

  • Complete instrument checks by running basic measurements with the Kappabridge, JR6, and Cryogenic magnetometer to ensure instruments are functioning properly.
  • If core orientation is scheduled for your cruise, then replace all 9V batteries in the TransIT adapters on the two Flexit computers. If you are planning to use the MI5 Icefield tools, make sure the Palms are charged and batteries are available for each tool. Do not put the batteries in the tools until ready to start a survey. Download data from the tool to the PC to ensure data transfers are working.
  • Train the scientists in the operation of the instruments used the most (e.g., Cryogenic Magnetometer, Agico spinner, Kappabridge magnetic susceptibility system).
  • Go over the various software packages with the Paleomagnetics scientists (e.g., SRM, Dtech2000, Rema6, Kappabridge programs, and Puffin Plot). It is especially important to familiarize the scientists with the operation of the SRM. The User Guide and Quick Start guide can be found on IODP Share.
  • The scientists may want to use specific software for coding or processing data. Check with them prior to arrival on site and facilitate software installation if necessary.
  • Remove any old or replicated SRM measurement sequences from C:\IMS\SRM CONFIG\Measurement Sequence\User
  • Clear out extraneous sample shape presets from the IMS-SRM software and make sure the appropriate presets for the expedition are available.

General

  • Assist in preparing to receive cores according to Corelab SOP

IV. DURING CORING OPERATIONS

The following is a list of actions that are accomplished once on site by technicians alone or cooperatively with the scientists assigned to the laboratory for an expedition.
A. SAMPLING
The basic magnetic measurements are conducted on whole/split sections and discrete samples:

  • Continuous measurements are done on archive halves of the cores. They are "fed" into the magnetometer by the scientists.
  • Discrete sampling is usually done by the paleomagnetists on the working-half of the core. Hard rock samples are to be sampled with a non-magnetic drill on a drill press or with the parallel saw for mini-cubes in the sample preparation area. Soft sediments are sampled using non-magnetic plastic sampling boxes.
  • Occasionally U-channels are collected from split core sections by scientists for post cruise analyses.


B. ROUTINE LAB MEASUREMENTS
The following is a list of the typical analyses done shipboard by the paleomagnetics technician and scientists. It is a good idea to discuss with the scientists at the beginning of the leg who will be responsible for which analysis. Data upload to LIMS is mainly the technician's responsibility.

  • Continuous Magnetic Remanence will be measured on archive halves of cores using the Cryogenic Magnetometer. The magnetometer can also be used to measure and demagnetize discrete samples. The work is usually done by the scientists. See the 2G Magnetometer manual and SRM software manual for specifics on running the instrument.
  • Discrete Magnetic Remanence will be measured on working half cubes or cylinders using the JR6A Spinner Magnetometer. The measurements will be collected by the scientists. See the JR6A user guide. The technician will perform data uploads to LIMS utilizing MegaUploadaTron periodically throughout the expedition.
  • Magnetic susceptibility and anisotropy of magnetic susceptibility (AMS) of discrete sediment and hard rock samples are acquired with the Kappabridge KLY-4S. The collection of data is usually done by the scientists. Refer to the vendor's manual for calibration instructions of the Kappabridge. Periodic uploads of Kappabridge data are completed by the technician.
  • Isothermal Remanence (IRM) and anisotropy of IRM can be imparted by an ASC Impulse Magnetizer. The collection of data is non routine and done by the scientists. The data are typically measured on the JR6A and can be uploaded. For operating instructions, refer to the Handbook for the Shipboard Paleomagnetist (Tech Note 34) and the ASC Impulse Magnetizer vendor guide.
  • Demagnetization of hard rock or soft samples can be done on the DTECH Demagnetizer or the Schonstedt Thermal Demagnetizer depending on the scientists' interest. For operating instructions of the two demagnetizers, refer to the manuals.
  • Orientation of cores recovered by piston coring is measured using the Flexit tools or the MI5 Icefield tools. The Paleomagnetics technician operates the instrument and processes the data.



C. GENERAL ACTIVITIES

  • Remain in contact with the Core Tech and Operations Manager while orienting APC cores. Make sure that the Flexit or MI5 Icefield Tools are exchanged every 8-12 hours.
  • Check Flexit battery voltages from the raw survey file and change the batteries when the voltage is below 8.5V. Check the battery voltage on the MI5 Icefield tool at the start of each survey. If the batteries are at 8.5V switch them out before starting a survey.
  • Upload Cryogenic Magnetometer data, orientation data, JR6 data, and Kappabridge data to LIMS using MegaUploadaTron. Cancel any duplicate uploads or remeasured runs after consulting with the paleomagnetists.
  • Clean and demagnetize the tray of Cryogenic Magnetometer at each change of shift or whenever deemed necessary (usually done by the scientists). Wipe down the tray with isopropyl alcohol and Kimwipes when cleaning. It's especially important to keep the track and boat clean when the sediment is changing from high intensity core samples to low intensity. Treat the bottom of the boat with antistatic liquid as needed to help minimize flux jumping.
  • Once a week check and record vital signs of the Cryogenic magnetometer and enter the data into the vital signs sheet and include in the tech report at the end of the expedition.
  • Ensure that all instruments are free of dirt, lubricated and fully operational in the lab.
  • Perform core lab duties according to Corelab SOP
  • Maintain good notes or a logbook for each instrument to document problems encountered and to monitor changes in parameters.
  • Check and maintain your inventory on a regular basis and submit orders to the Assistant lab officer. This includes both inventory and non-inventory items.
  • Update shipboard manuals and cookbooks on a regular basis.

V. DURING TRANSITS

  • Continue processing cores through the lab as described above

VI. DURING EXPEDITIONS

A. MAINTENANCE
In the Paleomagnetics Lab, a lot of the maintenance takes place on a daily or weekly basis during the expeditions as partially listed in the section above. However, for some instruments, maintenance is only required on a monthly or quarterly or yearly basis. The end of expedition maintenance is a must.

  • Monitor vital signs of Cryogenic Magnetometer weekly to ensure that temperature remains constant within the instrument.
  • Clean and lubricate the Flexit and MI5 Icefield tools on a regular basis.
  • Bi-annually, change the cryo-cooler compressor. And replace the adsorber in the compressor that is removed from operation so that the compressor is available as a spare.
  • Annually, have the ET's do maintenance on the Haskris and ship's chill water recirculating system. This should involve checking for any corrosion or leaks along the water lines.
  • Heat the SQUIDS and striplines especially after hard rock legs. Set the I-BIAS on the magnetometer. Make sure the noise level is normal.

VII. END OF EXPEDITION ACTIVITIES

  • Perform the end of leg maintenance as listed below.
  1. Clean the Flexit and MI5 Icefield tools and check if the o-rings are in good shape, otherwise replace them.
  2. Clean the boats for the Cryogenic Magnetometer.
  3. Clean the entire length of track.
  4. Carefully clean the Cryogenic Magnetometer outer surface.
  5. Clean the ceramic boats for the Thermal Demagnetizer.
  6. Empty the Haskris water tank using the wet vacuum. Replace the Haskris chill water with fresh water. Do not fill the tank with deionized water! The SRM should be running off of the ship's chill water when this task is completed.
  • Write the end-of-Expedition lab report, give a copy to the Lab Officer.
  • Make sure all data for all paleomagnetic systems are sent to LIMS and DATA1 before the MCSs cut off database access. All non-essential data should be erased from the hard disks of all the computers.
  • Pack up equipment being returned for repairs and give the Assistant Lab Officer the following information: IODP inventory number, value, weight, serial number, model number, vendor's name and country of manufacture.
  • Give the Lab Officer a list for port purchases, if any.

VIII. PORT CALL – Off Going

  • Find the oncoming Technical Staff for your lab and cross over. Make available a copy of your tech report for cross over. Make sure the on-coming staff is aware of any changes made to the lab, procedures, current equipment status, and port purchases if necessary.
  • See General JRSO Shipboard Technical Staff SOP.
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