Présentations Colloques

Oral Presentation
8.08
Session 8.08: Mineral and Thermal water: an indicator of deep processes and source of economically valuable minerals
Henriot Abel
The contribution of a multidisciplinary approach to conceptualize the structure and functioning of a complex Natural Mineral Water Glacial aquifer
The Evian (French Alps, France) Natural Mineral Water emerges at the bottom of a thick sedimentary pile of glacial sediments deposited, during the last glacial cycles, below and at the edge of the Rhône glacier. A multidisciplinary approach was implemented to more precisely define the geological structure and the hydrogeological functioning of this complex system. It is based on- (1) the detailed study and synthesis of existing boreholes geological logs, completed with field geological and geomorphological observations in order to reconstruct the local geological history and, from that, the main lithological facies. One of the main results is that the North-South growth of the glacier during the lemanic stage (-30 -27ky BP) infers a North-South sedimentary polarity with a pile of impervious basal tills on the northern proximal edge of the Plateau, and less impervious sediments in its the southern distal part, (2) the precise location and interpretation of the functioning of shallow aquifers’ springs and the plateau’s streams (discharge – time series data, and spatial variations -, hydrochemistry and isotopy, etc.), as well as deep piezometers, confirmed and clarifiprecised this scheme, and provided indications on the water transit time within the pervious layers of the sedimentary pile. In the Evian case study, these results prove to be of high interest to delineate the aquifer’s recharge area in order to implement efficient protection policies. Similar complex deposits are known in several places in the world (Alpine englaciation from the Alps to the Hymalaya, North and South Americas, New Zealand, etc.), where similar structure and functioning can be expected. The usefulness of a such a multidisciplinary approach is demonstrated. In fact, each method provides some clues that can only be considered as proofs when different methods provide convergent clues.
France