Abstract:

A multidisciplinary approach was developed to analyse the impact of the various tectonic joints on water and gas transfers in the carbonate aquifer of Quézac (southern Massif Central, France). Microtectonic measurements confirmed the local tectonic history and the structural map was completed by a morphostructural approach, using detailed photointerpretation of both aerial photographs and a digital elevation model. The past fluid transfers were discussed on the basis of field observations and the possible geodynamic context. The present fluid transfers observed in the field were related to four main groups of tectonic joints, based on a tectonic and morphostructural approach. The history of tectonic constraints, geodynamic context and fluid transfers was then reconstructed. It highlighted the major role of the north–south tectonic joints for water flows, followed by east–west joints, because of their longest karstification history. Joints with NW–SE and NE–SW orientations, which were more recently karstified, appeared to have less influence on water transfers. The weak gas production at the surface of north–south faults was explained by its dispersion owing to their intense karstification. On the basis of the innovative multidisciplinary approach, we propose a model for the water and gas preferential flow paths, taking the local tectonic and geodynamic context into account.

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