The GeORG project - Geological Potential of the Upper Rhine Graben - Situation, goals and first scientific results.
Résumé
The Upper Rhine Graben (URG) is an area with a great geological potential, in relation with many topical applications: deep geothermal energy, CO2 storage, hydrogeology, or seismic hazards. A detailed knowledge of the deep geological structure of the URG is needed to safely and successfully use this potential. The final goal of the INTERREG IV European GeORG project is therefore to gather complementary data from the German, Swiss, and French partners, in order to build a 3D geological model of the URG; the latter will ultimately model the geometry of 17 selected geological markers, chosen between the Variscan basement and the surface. The input data of this 3D Gocad model are mostly represented by the interpretation of about 5400 km of reprocessed seismic lines (3900 km in Germany and 1500 km in France), and the description of more than 1000 wells, both coming from the oil and mining industry. It's the first time that such an amount of subsurface data is gathered, studied and promote in the URG. The scientific interests are numerous, mainly regarding the structural frame of the URG. We aim to present the first results of our work, including new seismic interpretations and a first draft of the 3D model for the French side. We put the emphasis on the inventory of the various observed structural features (e.g. main border faults, normal and strike-slip faults, southerly Jura thrust front), and their implication regarding the structural evolution the URG. We also focus on the predominant role of the Miocene-to-present NNE-SSW strike-slip regime in the present-day 3D geometry of the URG; this strike-slip regime, characterized by the development of transtensional faults and negative flower structures, tends to obliterate the morphology of previous normal faults related to the first rifting phases of the URG, and therefore gives a distorted view of the pre-Miocene rift system.