HR: 16:50h
AN: GP44A-03 INVITED     [Abstracts]
TI: The Microwave Palaeointensity Technique
AU: * Hill, M J
EM: mimi@liverpool.ac.uk
AF: Geomagnetism Laboratory, Dept. Earth and Ocean Sciences, University of Liverpool, Oxford Street, Liverpool, L69 7ZE, United Kingdom
AB: Reducing laboratory induced alteration during palaeointensity experiments was the motivation for the group at Liverpool in the 1990s (led by John Shaw and Derek Walton) to start developing a new variant of palaeointensity methodology. Using high frequency microwaves, as opposed to heating using conventional ovens, it is possible to demagnetise and remagnetise samples. The microwaves directly excite the magnetic system so that it is not necessary to heat the whole bulk sample and excite the magnetic system via lattice vibrations. Thus, using microwaves can reduce sample alteration and the success rate of palaeointensity experiments can be increased. As with conventional methods, it is still necessary that the remanence is an original thermal remanence, which is held by non interacting single domain behaving grains. The development of the microwave palaeointensity technique from the early experiments using a domestic microwave oven, to the current systems operating at 14 GHz will be described. Results from studies that compare conventional thermal (Thellier) and microwave techniques, using both artificial and natural remanence will be described as well as summarising some of the palaeointensity results that have been obtained using the microwave palaeointensity method from archaeological, geological and even extra terrestrial material. Finally, future developments and applications of the method will be discussed.
DE: 1521 Paleointensity
DE: 1594 Instruments and techniques
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly