The microwave technique is used to determine the strength of the Earth's magnetic field in the past. It is usually applied to igneous rock such as lava and dike or the surrounding material that has been heated by them (baked contact), as well as heated archaeological material (ceramics, fireplaces, etc.). Samples are placed inside a resonant cavity and exposed to microwaves for a few seconds (typically 10 s). The microwave exposure is directly analogous to raising the temperature of the sample in the conventional Thellier technique, the main difference being that when the sample is exposed to microwaves most of the energy is absorbed by the magnetic system whereas in direct heating the entire sample absorbs energy.
By concentrating the energy in the magnetic system the bulk sample is not heated significantly. This reduces the probability of laboratory thermal alteration and provides a more accurate determination of the ancient magnetic field strength.
Microwaves magnons and temperature
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Bibliography
Hill, M.J., and Shaw, J., 2000. Magnetic field intensity study of the 1960 Kilauea lava flow, Hawaii, using the microwave palaeointensity technique. Geophysical Journal International, 142: 487–504.
Hill, M.J., Gratton, M.N., and Shaw, J., 2002. A comparison of thermal and microwave palaeomagnetic techniques using lava containing laboratory induced remanence. Geophysical Journal International, 151: 157–163.
Walton, D., Shaw, J., Share, J.A., and Hakes, J., 1992. Microwave demagnetisation. Journal of Applied Physics, 71: 1549–1551.
Walton, D., Share, J.A., Rolph, T.C., and Shaw, J., 1993. Microwave magnetisation. Geophysical Research Letters, 20: 109–111.
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2007 Springer-Verlag
About this entry
Cite this entry
Shaw, J. (2007). Microwave Paleomagnetic Technique. In: Gubbins, D., Herrero-Bervera, E. (eds) Encyclopedia of Geomagnetism and Paleomagnetism. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-4423-6_217
Download citation
DOI: https://doi.org/10.1007/978-1-4020-4423-6_217
Publisher Name: Springer, Dordrecht
Print ISBN: 978-1-4020-3992-8
Online ISBN: 978-1-4020-4423-6
eBook Packages: Earth and Environmental ScienceReference Module Physical and Materials ScienceReference Module Earth and Environmental Sciences