Dataset of P-wave velocity anisotropy measured on spherical samples of various rock types with an example of data analysis of retrogression related changes in eclogite and peridotite

Abstract

A dataset of ultrasound P-wave velocity measured in 132 independent directions and at confining pressure up to 400 MPa on 152 spherical samples is presented. The samples include sedimentary, metamorphic and igneous rocks from various geological settings and single crystals of quartz and plagioclase. The measured P-wave velocity data are accompanied by measured rock densities, calculated P-wave velocity anisotropies and by petrographic properties observed under the optical microscope. An example of analysis and interpretation of the dataset content is shown on a set of 27 eclogite samples and a set of 23 peridotite and pyroxenite samples included in the dataset. The impact of retrogression in eclogites and in peridotites and pyroxenites on the rock elastic properties is investigated. The eclogite retrogression has at its early stages only limited influence on the P-wave velocity. The progress of retrogression in eclogite is associated with gradual decrease in density and P-wave velocity. A more significant influence on P-wave velocity has been observed for the kelyphitization of garnet than for the pyroxene symplectitization. The serpentinization process associated with rapid density decrease is reflected by distinct decrease of P-wave velocity regardless of the rock type. The P-wave velocity anisotropy of analyzed sample sets is mostly dependent on the primary rock microstructure or on the later developed pore space. The pore space geometry documented by differences of P-wave velocity measured at increasing confining pressure is attributed to open microcracks in both rock types.