LABORATORY POSSIBILITY FOR REVEALING STAGES AND CONDITIONS IN HIGH-TEMPERATURE FIRING OF THE MUD BRECCIA USING ACOUSTIC EMISSION
1 Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences 2 Borok Geophysical Observatory of the Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences
Journal: Science and technological developments
Keywords: mud volcanoes, hydrocarbons, mud breccia, burning, acoustic emission, volcanic breccia, water loss
Аnnotation: In the paper, the process of laboratory high-temperature impact on the sample of mud breccia was investigated with acoustic emission (AE) tracking. Mud breccia was sampled on the Bulganak mud-volcanic field. The aim of the laboratory study was to simulate the baking of breccia in natural conditions during the “fiery” eruption of mud volcanoes associated with the ignition of associated volatile hydrocarbons. The sample was subjected to several cycles of heating-cooling to different temperatures (maximum up to ~750 °C). According to the analysis of AE activity changes in the heating process, several characteristic stages were identified, which are presumably compared with characteristic physical and chemical changes. During baking, two processes simultaneously develop that determine the AE activity change. First, the cracks formation is activated due to thermal expansion with a simultaneous increase in the brittleness of the substance. Second - the attenuation of elastic waves decreases. We assume that the main changes are associated with loss of bound water and oxidative processes. When discussing the results, a comparison with the data of structural and chemical analysis was carried out. The inhomogeneities of physical and chemical changes in the sample cross-section is recorded, which is associated with the inhomogeneities of redox conditions. The results indicate the influence of both temperature and redox conditions on the physicochemical transformations in breccia. This may allow us to assess the baking conditions and the composition of the associated hydrocarbons in “fiery” eruptions.