Alteration and deformation of fault-generated pseudotachylytes

• Applicant: Dr. Marieke Rempe
• Subject Area: Palaeontology ; Mineralogy, Petrology and Geochemistry ; Geophysics
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 403438118

We propose to explore the kinetics of processes that govern the alteration and deformation of pseudotachylyte and associated microstructural characteristics to quantify the likelihood of their preservation and recognition by combining laboratory and field investigations. We will conduct high-temperature, high-pressure alteration and deformation experiments on natural pseudotachylytes and synthetic analogue materials representing a range of generation scenarios and alteration stages. The experiments will provide diagnostic features against which we will compare microstructures of natural fault-generated pseudotachylytes collected in the field to evaluate their alteration history. As fault-generated pseudotachylyte, a type of fault rock that preserves evidence of frictional melting, appears to be relatively rare considering the frequency of earthquakes and commonly accepted source models that predict melting conditions to be coseismically reached for large crustal earthquakes, the proposed study will provide answers to the pressing question whether pseudotachylytes are in fact rarely generated or rarely preserved in a recognizable form. Answering this question is a mandatory prerequisite to fully exploit the field record for the derivation of earthquake-source parameters and the properties of fault rocks at depths. Complementary to seismological analyses of recent earthquakes, the proposed experiments and microstructural work will provide independent constraints on the energy budget of earthquakes.

• DFG Programme: Research Grants
• International Connection: Italy
• Co-Investigator: Professor Dr. Jörg Renner
• Cooperation Partners: Professor Dr. Giulio di Toro; Professorin Dr. Claudia Trepmann