Signs of cavitation phenomena in multi-phase hydrothermal mineralisation in the Ryj Fault, Holy Cross Fold Belt

Two stages of syn-tectonic hydrothermal mineralization were identified in the damage zone of the Ryj Fault in the Holy Cross Fold Belt. The first stage, related to post-Caledonian movements, contains rutile, zircon, mica, kaolinite, "illite" and quartz. The second, connected with the Variscan period, contains hematite, Fe-Ti oxide microparticles and native iron spherules. Rapid fluid migration caused by fault activity led to the occurrence of cavitation phenomena in the damage zone. The cavitation bubbles that formed then imploded, leading to increased erosion. The aim of this paper is to demonstrate that atypical erosion structures observed in rutile and quartz crystals and the occurrence of native iron microspherules in the repeatedly tectonically activated Ryj Fault are the result of the cavitation phenomena. These phenomena can also occur due to turbulent flow without any fault movement indicating that cavitation erosion may facilitate subsequent fault activation. Cavitation can affect the pressure and temperature records in geothermometers and geobarometers, therefore the possibility of its occurrence should be taken into account when determining the deformation behaviour. The cavitation-induced temperature increase is sufficient to disturb the isotopic composition of minerals, which poses a risk of obtaining discrepant results in radiometric dating and thermochronological investigations.