Abstract: As a rapid and sensitive petrofabric tool, the anisotropy of magnetic susceptibility (AMS) has been extensively used in studying rock fabrics. Sometimes it is difficult to drill an intact oriented core sample without any crevice, in which various filling minerals can be found. To analyze the crevices’ effect on diabase magnetic fabrics, 160 diabase samples with crevices are selected to study the AMS data then remove the filling minerals in the crevices in order to compare magnetic fabric characteristics of the diabase before and after the treatment. The data analysis shows that the average difference in the AMS intensity of all the specimens is less than 1% and the difference in the average direction also falls in <1°. From the results, we conclude that crevices of diabase dykes hardly have much influence on the AMS features. Mineralogy and rock magnetic studies indicate that the main mineral constituents in the diabase crevices are quartz, feldspar, hematite, pyrite, and chlorite. The AMS intensity of these filling minerals is about one thirtieth of diabase that is dominanted by ferromagnetic mineral of magnetite, which makes crevices to have no much effect on the AMS results.

Key words: crevices of diabase dykes, AMS, SEM, LRS, thermomagnetic curves