Fault zone evolution during Cenozoic tectonic inversion in SE Korea

Abstract

Geometric and kinematic analyses were conducted on a fault zone at a construction site in SE Korea to understand its temporal and spatial evolution. This area is tectonically characterized by the existence of reversely reactivated faults associated with Cenozoic tectonic inversion. Structural elements within fault core such as slip surfaces and gouge zones are examined in a great detail based on grid-mapping analysis in a nearly three-dimension, combining the vertical sections with various directions. The highly deformed zone is composed of multiple gouge zones and geometrically characterized by anastomosing patterns. Kinematic indicators and their cross-cutting relationships indicate that the fault zone evolved by multiple slip events including reverse reactivation of a pre-existing normal fault zone. This implies that tectonic inversion is one of the most important factors controlling the complexity of the architecture of the studied fault zone, and it is important to understand the evolutional history of mature (or evolved) faults. Detailed analysis of geometric and kinematic characteristics of mature fault zones can provide very useful information to various research fields, such as fault zone evolution, interpretation of local tectonics, geotechnical stability, and fault zone modeling associated with fluid flow.