a. Detailed geological map of Rennes-les-Bains (location in Fig. 2b) modified after Bessière et al. (1989) with microstructural analysis locations. The Arques NE-SW normal fault crosses the Cardou Thrust, which changing vergences, controls the Maastrichtian to Paleocene sedimentation. The Fontaine salée (ID 8) spring is also represented on the map. b. Nearly horizontal outcrop at the river bed RB2: Hotspring Bains de la Reine and NE-SW fracturation (cleavage) of the Coniacian series. c. Outcrop RB3: Joints into the Devonian series. d. Outcrop RB4: Thanetian conglomerates affected by N25 sinistral strike-slip displacement (post- ca., 55 Ma) along the Arques fault. e. Outcrop RB5: Breccia in Maastrichtian limestones along a N40 fault. f. The Fontaine salée spring: white color is induced by dissolved evaporites (Tab. 1).