Understanding fracture mechanisms in garnets from ultra-high-pressure rocks by combining chemical data and residual stress measurements

• Applicant: Professorin Dr. Lucie Tajcmanova
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 535198529

This project aims to improve our understanding of fracture mechanisms in ultra-high pressure (UHP) rocks by investigating chemical variations and residual stress distributions in garnets. Fractures are important mechanical indicators of high stress variations and have been used to interpret changes in P during decompression of metamorphic regions. The project will focus on the analytical and petrographic studies of garnets from the UHP rocks of the iconic Dora Maira locality (W Alps) and the coesite-bearing garnets from the Śnieżnik Massif (SW Poland). High angular resolution electron backscatter diffraction (HR-EBSD) analysis will be used to map the distribution of residual stresses in the garnets. The data obtained will provide a comprehensive set of petrological data that will help unravel the process of fracture across the mineral grains. By comparing the residual stress maps obtained before and after fracturing, the study aims to elucidate the process of stress build-up and release during fracturing. This information will be instrumental in revealing the mechanisms of fracture propagation and the specific conditions that trigger different types of fractures. These data will serve as fundamental observations to be compared with numerical models in follow-up projects. The results will not only improve our understanding of fracture mechanisms in UHP rocks, but will also provide important insights into stress build-up and relaxation in geological materials in general.

• DFG Programme: Research Grants