Paleomagnetism Onboard the IODP Research Vessel JOIDES Resolution: Recent Advances, Best Practices, and Pitfalls
Abstract
One of the largest openly available paleomagnetism databases is derived from paleomagnetic data acquired continuously along drill cores collected by the International Ocean Discovery Program (IODP) and its predecessors. The bulk of data are magnetic remanences measured using superconducting rock magnetometers (SRMs) with automated track systems and in-line alternating field (AF) demagnetization units produced by 2G Enterprises. Our goal in this study is to (1) report on the new SRM that was installed onboard the JOIDES Resolution in December 2016 prior to the start of IODP Expedition 366, (2) consider best practices that may aid shipboard scientists in collecting high quality data, and (3) discuss common pitfalls associated with using an SRM in the shipboard environment to measure a diverse range of lithologies collected in metal core barrels that pass through a relatively strongly magnetized drill string. From a series of tests conducted on the new SRM during a June 11-13, 2017 port call, our main conclusion was that the new magnetometer is functioning as designed. While overall its capabilities are comparable to the previous magnetometer, the new SRM does have several significant advances, including better flux counting, which allows more strongly magnetized rocks to be measured accurately. It also performs AF demagnetizations at high fields (up to 80 mT) without imparting spurious anhysteretic magnetizations, which was a common problem in the old SRM. A worrisome observation, and one that has been made in many shore-based labs, is that devices that emit radio-frequency electromagnetic waves, like actively transmitting cell phones, interfere significantly with SRM measurements. This pitfall will likely have to be addressed on all forthcoming cruises unless better electromagnetic shielding for the SQUID sensors can be found.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMGP43B0976A
- Keywords:
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- 0694 Instruments and techniques;
- ELECTROMAGNETICS;
- 0699 General or miscellaneous;
- ELECTROMAGNETICS;
- 1594 Instruments and techniques;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 1599 General or miscellaneous;
- GEOMAGNETISM AND PALEOMAGNETISM