Microstructure and composition of brittle faults in claystones of the Mont Terri rock laboratory (Switzerland): New data from petrographic studies, geophysical borehole logging and permeability tests

Claystones are considered as a geological barrier. However, the properties of claystone may be modified if these are cut by brittle faults and fractures. Investigations of fault rocks are therefore crucial to evaluate the barrier properties of clay rich formations.