The effect of rock fabric on P-wave velocity distribution in amphibolites

• Published in: Physics of the earth and planetary interiors Vol. 114; no. 1; pp. 39 - 47
• Main Authors: Vajdová, V, Přikryl, R, Pros, Z, Klı́ma, K
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 06-07-1999
• Subjects: Amphibolites; Grain size; Image analysis; Laboratory measurement; P-wave velocity anisotropy; Rock fabric; Shape-preferred orientation; Grain size; Image analysis; Amphibolites; Rock fabric; Shape-preferred orientation; Laboratory measurement; P-wave velocity anisotropy
• ISSN: 0031-9201; 1872-7395
• DOI: 10.1016/S0031-9201(99)00044-8

This study presents contribution to the laboratory investigation of elastic properties and rock fabric of amphibolites. P-wave velocity was determined on four spherical samples prepared from a shallow borehole core. The measurement was conducted in 132 directions under various conditions of hydrostatic pressure (up to 400 MPa). The rock fabric was investigated by image analysis of thin sections that enabled precise determination of grain size, modal composition and shape parameters of rock-forming minerals. Laboratory measurement of P-waves revealed pseudoorthorhombic symmetry of rock fabric in amphibolites studied. This symmetry reflects rocks' macro- and microfabric. Maximum P-wave velocity corresponds to the macroscopically visible stretching lineation. Minimum P-wave velocity is oriented perpendicular to the foliation plane. The average grain size is the main microstructural factor controlling mean P-wave velocity.