Geometry and kinematic evolution of a long-living foreland structure inferred from field data and cross section balancing, the Sainte-Victoire System, Provence, France

Abstract

The Sainte-Victoire System (SVS) is a key area to understand how the shortening is accommodated in outer foreland of the Pyrenean-Provence orogen between Late Cretaceous and Eocene. Structural data, growth strata and fault slip analysis, and four balanced cross sections are used to decipher the along-strike geometry, deformational characteristics and kinematics of the SVS. The SVS is divided into two structural domains separated by a regional relay zone: the eastern domain is governed by a N-vergent thin-skinned tectonic style above Triassic series and the western domain, by a mixed S-vergent thick- and thin-skinned tectonic style with tectonic inversion of Late Paleozoic-Triassic half grabens. Growth strata indicate that the eastern SVS grew during Danian as a result of shortening transfer from the southern Arc Basin. In contrast, the western SVS is an independent structure which has recorded the early stage (∼83 Ma) of shortening and focused continuous deformation during ∼40 Myr. The shallow N-S shortening is ∼5 km (∼25%) and ∼8 km (∼34%) in the western and eastern SVS, respectively. At a regional scale, the tectonic inversion of the SVS and the Arc Basin recorded a deep shortening of the order of 15-18 km (∼34%). Although the shortening magnitude of the SVS remains small, other structures similar to the SVS were synchronously active across foreland basin, suggesting a significant amount of cumulated shortening. This outer foreland shortening may account for a non-negligible amount of deformation at the Pyrenean-Provence orogen scale. © 2012. American Geophysical Union. All Rights Reserved.