ABSTRACT
The Opalinus Clay can be characterized as an overconsolidated clay formation consisting primarily of thinly laminated, silty and sandy shales, which can be grouped into three main facies: the shaly facies, the sandy facies and the carbonate-rich sandy facies (Thury & Bossart 1999). Detailed geological mapping in the Mont Terri rock laboratory revealed three different tectonic fault systems: a bedding-parallel SSE dipping fault system, a low angle SSE to SW dipping fault system, and a N to NNE trending fault system (Bossart & Thury 2008). The most significant tectonic structure identified in the rock laboratory is a 0.8 to 2 m thick fault zone associated with the bedding-parallel SSE dipping fault system. Most of these fault planes show slickensides indicating a thrusting movement in NNW direction (Bossart & Thury 2008).
