Three-dimensional Geometry and Forward Numerical Modeling of the Sant Corneli Anticline (Southern Pyrenees, Spain)

This work is based on a three-dimensional (3-D) reconstruction methodology for geologic structures from field and subsurface data. The methodology consists of several steps: (1) collection and georeferencing of data, i.e., 3-D digitalization; (2) analysis of data and definition of a 3-D geometric and stratigraphic model, i.e., structural and stratigraphic analysis; and finally, (3) the reconstruction of key surfaces that form the structure, i.e., reconstruction of the reference surface and reconstruction of additional surfaces, both honoring the defined geometric model. The methodology has been applied to a natural example, the Sant Corneli anticline, a thrust-related fold located in the southern Pyrenees. This fold, oriented approximately east–west, has a complex 3-D geometry, with stratigraphic and structural variations, both laterally and vertically. This chapter focuses on the study of the Late Cretaceous postrift series. Outcrop information has been collected to reconstruct the superficial geometry of the Sant Corneli anticline. Seismic profiles that cross the area have been interpreted to reconstruct the geometry of the thrust fault at depth. The reconstruction methodology at surface and at depth is made following the same workflow, adapting it to the different nature of the original data sets. At the same time, the use of 3-D forward numerical modeling allows us to explore the relationship between the fold and the thrust, the main factors that influence fold development through space and time, and to find the kinematic model(s) that best fit the proposed 3-D reconstruction. The main contribution of this work is the incorporation of forward modeling techniques in the 3-D reconstruction workflow to independently establish the relationship between the various reconstructed geologic surfaces. Once this relationship is known, it is possible to refine the reconstructed surfaces and integrate them in a single and comprehensive 3-D model that honors both the available data and the established kinematic model. This technique is also used to analyze the possible kinematic evolution of a fault-related structure that best reproduces the deformed geometry obtained through the 3-D reconstruction process. Moreover, this study also improves the developed 3-D reconstruction methodology as it incorporates the use of isopach maps.