Fig. 7 

Near-surface cross-section with seismic interpretations. The cross-section derives from surface and well data. The section trace crosses the Reculet Thrust, the Crêt Chalam Thrust with its imbrications, the Tacon Thrust, the Bienne Thrust and terminates in the north-west at the front of the Oyonnax Backthrust. The seismic lines have been converted with the new multi-layered velocity model (Fig. 6b). These seismic-depth interpretations allow to position the horizons and the faults with more precision than simpler conversion models. The interpreted horizons and reflectors of the seismic lines 81-JU-06, 82-JU-18, SJ1U3 and GG87-02 (b) have been projected on the initial cross-section (a) parallel to the regional fold axial trend (N35°). The interpretations of the 81-JU-06 seismic line are offset due to the projection. A gap of seismic data exists between the Geneva Basin and the Valserine Syncline. Despite this gap, the initial cross-section (a), the seismic horizons and interpreted faults and thrusts (b) helped to have an insight of the deep structures with good accuracy for the forward modelling. The cross-section (black straight line) the wells (red dots) and seismic lines (in black) are located on the small map (c). T. thrust, B.-T. backthrust, S. syncline, A. anticline