Geophysical research: article

Аnnotation: The article discusses the results of ultrasonic testing of samples of clay rocks of a breccia-like structure during stage-by-stage heating to temperatures of 800 and 1100 °С. The experiments were carried out in order to study the change in the velocities and attenuation of elastic waves during mineral and structural transformations in the rock in the course of thermal metamorphism. The objects of study were samples of a mud breccia of a group of mud volcanoes. During the experiment, the velocity of the longitudinal wave in the samples after heating was determined. Changes in mineral composition were monitored using X-ray diffraction analysis; to control structural changes, thin sections were studied at different stages of heating. The attenuation of a longitudinal wave was analyzed by the method of spectral ratios. Analysis of the dependences of the longitudinal wave velocity on the heating temperature for different mud volcanoes made it possible to group volcanoes, presumably according to the depth of the feeding foci. At the same time, the analysis of changes in attenuation and mineral composition does not contradict the conclusions drawn from the analysis of velocities. When carrying out the described experiments, a new methodological approach has been developed, which enables to study samples of weakly consolidated rocks in laboratory conditions at frequencies of ultrasonic range.