Ultrasonic Velocities in some Metamorphic Rocks

Sound velocities, both longitudinal and torsional, are measured in some metamorphic rocks by employmg the ultrasonic pulse method involving the phenomenon of total internal reflection. Their variation in these rocks with the grain size has been examined in detail. Velocities decrease with increasing grain size and in fact vary linearly. The effect of granular structure on the transmission of sound is also studied. The effect of temperature on the velocities of sound in metamorphic rocks in a range of 3°-110° c has been thoroughly investigated. An attempt has also been made to correlate the variation of velocities with the petrogenetic history of the rock.