The Nappe du Promontoire de Québec is located in the frontal part of allochtonous units of the Canadian Appalachians. Cliff exposures in the south-east of Québec city are composed of subvertical Ordovician limestones and shales. They are jointed and 60% of the fractures are mineralized. Whereas the remainding 40% contain no filling. In open joints, early extension is recorded by fibrous calcite followed by bitumen and euhedral translucent quartz. Only about 1/3 of opened fractures show the complete sequence of filling suggesting that they have channeled the same fluids.

         Two sets of joints, front-parallel and front-normal joints, are defined according to their geometrical relationship to layering or fold axes. They are respectively oriented mainly SSW and WNW with a shallow dip. Sigmoidal en-echelon veins show dextral movement. Later large NS shear zones with shallow dips to the east display either sinistral or dextral movement. The infilling paragenesis is the same as in the previous joints. A late euhedral calcite is encountered in these shear planes and in some rare filled joints.

         To characterize the fluid circulation in this nappe, the study of the fluid inclusions in the joint fillings is adressed. Petrographic observations show primary and secondary fluid inclusions both in calcite and quartz. In calcite the fluid inclusions are very abundant with  variable shapes. They are small, biphase with a different V/L ratios attesting to post trapping phenomenon. Some planes show inclusions with a constant V/L ratio. The quartz contains bi- to multiphase inclusions of different sizes. They are along planes or isolated clusters. Some inclusions homogenize at low temperature suggesting the presence of CO2?. Hydrocarbon inclusions are common in quartz.

         Significant permeability is attested by the abundance of fractures within these rocks. This nappe is a good example of water-rock interactions linked to nappe emplacement. The fluids have migrated as a function of the deformational context and the distribution of P,T gradients. These fluids produced similar mineral assemblages in fracture sets of different orientations suggesting that they migrated during several cycles under changing conditions.