Normal fault growth in layered rocks with contrasting lithologies: a case study from the upper tip of the Argence Fault (Charente, France)

Abstract

Increasing displacement along an isolated fault is generally associated with fault propagation within the host rock. This propagation is controlled by several factors, including host-rock lithology, tectonic context and the presence of preexisting structures. Consequently, fault propagation is rarely linear and continuous, instead often alternating between periods of propagation and arrest, or propagation locking. We present structural data collected in a field at the terminal tip of the Argence Fault, one of the regional normal faults in the northern part of the Aquitaine Basin. At the outcrop, the fault cuts a heterogeneously layered sequence of limestones, marls and clays. We observed a well-exposed tip of this fault, and analyzed the deformation patterns. This analysis provided insights into the processes involved in the formation of fault zones, the fault damage zone in particular, and the effects of contrasting mechanical properties on modes of fault growth.

Keywords

• Charente
• Normal fault
• Fault propagation
• Damage zone
• Core zone
• Aquitaine basin
• Charente