Relationships between Lithospheric Flexure, Thrust Tectonics and Stratigraphic Sequences in Foreland Setting: the Southern Apennines Foreland Basin System, Italy

Abstract

We discuss here tectonics and sedimentation processes occurring during continent-continent collision and relationships between accretionary processes on overplate, flexural lithosphere on underplate and related controls on clastic sedimentation in developing foreland basin systems. This paper focuses on and clastic sedimentation developed during the sequential history of an orogenic system, in the Mediterranean Region. These clastic trends, covering a large time span from Early Mesozoic to the present, may contribute: (1) to the paleogeographic and paleotectonic reconstructions of the southern Italy portions of the western Mediterranean orogen, and (2) to the general models of complex relationships between clastic sedimentation and paleotectonic history of other major orogens. The evolutionary record of Earth’s processes preserved in the form of sedimentary rocks has been pivotal in paleogeographical and paleotectonic reconstructions of source/ basin systems. Compositional trends of clastic strata through space and time are used to infer the structural history of adjacent mountain belts and to monitor the key geodynamic changes during orogenic processes (e.g. Dickinson, 1985, 1988; Critelli & Ingersoll, 1994; Critelli, 1999). The controls on the composition and dispersal pathways of clastic strata along the convergent plate margins have long been debated (e.g. Dickinson, 1988; Ingersoll et al., 1995). Clastic infilling of sedimentary basins in orogenic systems have been used as important indicators of tectonic activity and climatic changes. In the orogenic systems, clastic sedimentation may record the accretionary processes, the accomodation of the thrust units, and the flexural features of the foreland plate. The development of an orogenic wedge during continental collision results in thickening of the crust. The excess mass of this thickened crust acts as a load on the underthrust plate, causing it to be flexed downwards close to the load, so developing a foreland basin (e.g. Beaumont, 1981; Sinclair and Allen, 1992). During plate convergence, the vertically acting load of the mountain belt migrates over the foreland plate, thus resulting in the migration of the associated foreland basin. The foreland is the region between the front of a thrust belt and the adjacent craton (e.g. Dickinson, 1974; Bally and Snelson, 1980; Allen et al., 1986; Miall, 1995). Large volumes of clastic sediment are derived from erosion of the thrust belt and deposited in the foreland