Abstract

During Early, as proposed by the International commission on stratigraphy Pleistocene times, interacting fluvial and aeolian processes constructed wide alluvial plains over an evaporite-dominated Miocene substratum in the central Ebro Basin. An exceptional site where these deposits show faults, folds, diapirs, karst structures and unconformities has been studied in detail. Analysis of particular structures demonstrates the interaction by that time of tectonic faulting, diapirism, karstification and sedimentation in an area where deformation was traditionally linked to the presence of underlying evaporites, without proposing any precise mechanism. Multiple approaches (sedimentology, structural geology and geophysics) have been used in order to discriminate the origin of each type of structure as well as to understand the interaction between different processes. Numerous normal faults and fractures of variable size are consistent with the regional stress field. Pleistocene deposits are pierced by diapirs of Miocene evaporites and disrupted by karst structures with different geometries (tubular, funnel and vault), both partially controlled by tectonics. The example described is proposed as an analogue model that could successfully illustrate evolution patterns of basins of potential interest for petroleum geology where similar processes have actuated, resulting in complex stratigraphical architectures.

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