In Situ U‐Pb Dating of Calcite and its Application to the Study of Brittle Faults

ABSTRACT Brittle faults record tectonic deformations of the Earth's surface and interior. Constraining their active timing is crucial for reconstructing geotectonic evolution, constraining seismicity models, and assessing seismic hazards. However, the low temperature and pressure conditions of brittle fractures and the fast strain rate of rocks pose significant challenges for dating brittle faults. Recently, in situ U‐Pb dating of calcite has emerged as an important method due to its high resolution, low detection limits and short detection periods. This method requires identifying calcite characteristics and determining its genetic types in the field. Here, we summarise the main methods for constraining the timing of brittle fracture activity, the basic principles of in situ U‐Pb calcite dating, and the field types and petrographic characteristics of syntectonic calcite. We also present case studies of in situ U‐Pb dating of calcite in major fault zones as reference points. This study provides a overview of in situ U‐Pb calcite dating techniques, highlighting the critical role of field and petrographic characteristics in accurately dating brittle fault activity and demonstrating their application in constraining the timing of tectonic events, which offers valuable insights for understanding tectonic evolution and assessing seismic hazards.