COMPARATIVE MEASUREMENTS OF MAGNETIC FABRIC BETWEEN KAPPA BRIDGES AND MINISEPS

The Anisotropy of Magnetic Susceptibility (AMS) is a ubiquitous feature of rocks which reflects a tendency about the alignment of magnetic grains of minerals in it,i.e. magnetic fabric. In the last 30 years,the technique of magnetic fabric has been widely and efficiently applied to geology and geophysics,showing its prospects. Different principles are used for the development of instruments for AMS measurement. The consistency and reliability of the results obtained by different instruments should be checked and confirmed for a specimen through comparative measurements. The test was carried out by Kappa bridges (KLY-1,2) and Mi-niseps (Molspin Ltd.,U. K.) using cubic or cylindric specimens which are of different materials,i.e. loess,metamorphic rock,basalt or a compressed mixture of fault clay and SD magnetite. Consequently,(1) it is found that the repeatability of measurement by a Kappa bridge is often slightly better than that by a Minisep. (2) The calibration value for measuring the Kz depends on the susceptibility printed on the standard sample and the volumetric ratio of the standard specimen and to the specimen measured. And the calibration value for the spin measurement should be half the above-said calibration value for Kz measurement.