Three-dimensional architecture of growth strata associated to fault-bend, fault-propagation, and décollement anticlines in non-erosional environments

Abstract

Abstract The evolution of surficial structures at the toes of orogens arises from the complex interplay between tectonic and surface processes. The internal architecture of syntectonic sediments has been shown to provide useful insights on the kinematic mechanism of folding. Two-dimensional templates of growth strata patterns associated to thrust-related anticlines are available in the literature. In this paper, we show the results of three-dimensional numerical modelling of growth fault-bend folds, fault-propagation folds, fixed limb length decollement folds and fixed limb dip decollement folds. We point out that total thickness contour maps, single syntectonic layer contour maps, and above all, the computation of their directional first-derivative maps, provide useful templates for inferring the kinematic mechanism of folding when compared with similar maps from natural examples. Application of these three-dimensional numerical models includes the comparison and supervised best fit with three-dimensional seismic reflection data sets. Numerical results are contrasted with the growth strata map patterns of the Mediano, Oliana and Pico del Aguila anticlines, in the Spanish Pyrenees.