MAIN RESULTS OF THE ECORS PYRENEES PROFILE

The 250 km long, deep Seismic reflection survey across the Pyrenees from one foreland (Ebro Basin) to the other (Aquitaine Basin) was designed to study the structure of the deformed Mesozoic boundary between the Iberian and European Plates. The results are: 1. (1) the entire crust shows well-defined reflectors with a general fan-shape geometry; 2. (2) a deep layered domain is evident above the Moho discontinuity; 3. (3) near the surface in the external domains, reflectors accurately define the geometry of major thrusts and structures affecting the Mesozoic and Cenozoic cover of the Pyrenees; 4. (4) the middle crust shows two major sets of Seismic events interpreted as Hercynian structures. Using these results, a balanced structural section of the Pyrenean belt is proposed. The mode of thickening of the crust during the Alpine orogeny is briefly discussed; only the Iberian crust was significantly thickened by a southward stacking of slabs. © 1990.