Complex Dielectric Properties of Several Igneous and Metamorphic Rocks
Technical rept. 1 Jul 1975-30 Sep 1980
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES
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The complex dielectric properties of rocks are interesting scientifically and important practically. The scientific interest derives from a desire to understand the properties of materials, the electrical structure of the earths crust, and the electrical loss mechanisms in the crust. The practical significance stems from potential applications in borehole logging, geothermal prospecting, mineral prospecting, and in lithospheric radiowave communications. The real part of the permittivity epsilon of a rock is an average of the permittivity of the individual minerals the volume fraction of each mineral appears to be a suitable weighting function for most purposes. The loss factor epsilon obviously depends on the various loss mechanisms present and on the frequency. In rocks, the value and behavior with temperature and frequency are dominated by the water and dissolved ions present in microcracks. In this study, we have removed the water from the microcracks in order to obtain data suitable for use in inferring the properties of rocks at depths where the microcracks are not present. Such depths may be as shallow as 1 km.
- Geology, Geochemistry and Mineralogy
- Electricity and Magnetism