Complex geometry and kinematics of subsidiary faults within a carbonate-hosted relay ramp

• Published in: Journal of structural geology Vol. 130; p. 103915
• Main Authors: Mercuri, Marco, McCaffrey, Ken J.W., Smeraglia, Luca, Mazzanti, Paolo, Collettini, Cristiano, Carminati, Eugenio
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-01-2020
• Subjects: Carbonate-hosted faults; Fault kinematics; Relay ramp; Slip tendency; Tre Monti fault; Virtual outcrops; Virtual outcrops; Carbonate-hosted faults; Fault kinematics; Slip tendency; Relay ramp; Tre Monti fault
• ISSN: 0191-8141; 1873-1201
• DOI: 10.1016/j.jsg.2019.103915

Minor fault geometry and kinematics within relay ramps is strongly related to the stress field perturbations that can be produced when two major fault segments overlap and interact. Here we integrate classical fieldwork and interpretation of a virtual outcrop to investigate the geometry and kinematics of subsidiary faults within a relay ramp along the Tre Monti normal fault in the Central Apennines. Although the Tre Monti fault strikes parallel to the regional extension (NE-SW) it shows predominant dip-slip kinematics, suggesting a NW-SE oriented extension acting at sub-regional scale (1–10 km). Conversely, the slickenlines collected on the front segment of the relay ramp highlight right-lateral kinematics. The subsidiary faults in the relay ramp show a complex geometry (variable attitudes) and slickenlines describe multiple kinematics (left-lateral, dip-slip, right-lateral), independently of their orientation. Our fault slip analysis indicates that a local stress field retrieved from the kinematic inversion of the slickenlines collected on the front segment, and likely promoted by the interaction between the overlapping fault segments that bound the relay zone, can explain most of the geometry and kinematics of the subsidiary faults. Further complexity is added by the temporal interaction with both the regional and sub-regional stress fields.
•Integration of classical fieldwork and virtual outcrop interrogation.•Geometry and kinematic analysis of minor faults within a relay ramp damage zone.•Subsidiary faults display geometrical and kinematics complexity.•Temporal interaction of various stress fields at a local scale.