The Spanish Pyrenees provide world-class models for thrust tectonics and synorogenic sedimentation. During the field seminar we will examine illustrative outcrops of thrusts, fault-related folds, stratal architectures and facies of depositional systems affected by growing structures, which are good analogues for hydrocarbon reservoirs. The seminar will cover a transect of the southern Pyrenees, a Cenozoic belt where thrust-fold geometries are well exposed and suitable for conceptual discussion. Synorogenic sediments range from deep-water turbidites to shallow marine and terrestrial molasse. Turbidites include debris sheets ("megaturbidites") that have produced gas. Molasse sediments are perturbed by growth anticlines and exhibit intraformational unconformities related to observable thrust faults.
The field trip takes place in beautiful mountain scenery, which is a plus to the geology. During the days of the trip, lodging will be in a comfortable hotel in the touristic/historic town of Jaca, a famous center for winter and summer leisure activities. Accompanying guests may enjoy visits to the XI century Romanesque cathedral and the XVI century fortress.
The first day comprises the travel from Barcelona to Jaca and a general presentation to the seminar after the arrival, including the geology of the Pyrenees and an introduction to the concepts to be studied. In the next day, the field work is initiated in the Roncal valley, where we will study the internal thrust sheets of the Pyrenees that illustrate the process of inversion of the pre-orogenic extensional margin of the Iberian plate. Patterns of fractures and other minor structures related to thrusting will be discussed. The third day is centered on an itinerary on the scenic Aragüés valley, studying in detail thrust-fold geometries and examining deformed synorogenic turbidites. The fourth day is devoted to the classic turbidite and breccia deposits of the Hecho group in the Jaca basin, and to the analysis of growth strata and related unconformities at the internationally known example of the Pico del Aguila anticline. The last day involves a reconnaissance of the south Pyrenean mountain front at Riglos (Gallego gorge), analyzing interactions between growing thrust structures and proximal alluvial fan conglomerates, and concludes with the return to Barcelona in the evening.
The field work involves some walking in mountain terrain, always along safe and well-marked trails. On the third day we walk up a difference in elevation of 450 m. Good exposures of thrust faults and folds make the hike worth! The trail is well marked, and return to a hut or to the vans is always accessible. We recommend hiking boots, sun protection cream, and a hat.