Introductory Studies of Natural and Artificial Argillaceous Aggregates by Sound-Propagation and X-ray Diffraction Methods

Abstract

Field evidence has shown wide variation in the velocities of sound waves in shales, the most abundant sedimentary-rock type. The sound velocity in and the bulk densities of a variety of natural and artificial aggregates were measured, and an attempt was made to show how mineral composition, particle orientation, and interparticle adhesion affect the velocity-density relationship. In natural samples minerals were identified by X-ray diffraction, and the degree of preferred orientation of the illite particles was measured by comparing the ratio of the intensities of the (002) to (110) lines obtained from irradiated sections cut parallel and perpendicular to the bedding. Sound-velocity measurements and X-ray results indicate that the bedding planes of flat-lying argillaceous sediments have circular symmetry for all stages of compaction and that the degree of preferred orientation parallel to the bedding plane of the basal planes of illite particles increases with increasing compaction. Large differences in s...