Tectonosedimentary evolution of the Plio-Pleistocene Sant'Arcangelo Basin (Southern Apennines, Italy)

This paper describes a new tectonosedimentary model for the evolution of the Plio- Quaternary Sant'Arcangelo Basin, located in the Southern Apennines of Italy. To this purpose, we carried out a new field survey of the basin fill, closely integrating stratigraphy, facies analysis, and structural and tectonic analyses. The geological map at 1:50 000 scale of the whole basin is the first result of this work. We present a new stratigraphic framework for the Sant'Arcangelo Basin succession, which has been subdivided into five major stratigraphic groups, classified as synthems, following the recognition of major basin-wide unconformities. The synthems include smallerscale stratigraphic units, which are classified as depositional sequences or sub-synthems. These sub-units are composed of different lithofacies assemblages recording cyclic activation of fluvial, deltaic, shallow marine and lacustrine environments throughout the evolution of the basin. Integration of facies analysis and tectonic data led to the definition of a series of palaeogeographical sketches, encompassing the Piacenzian and late Pleistocene, which mark the main steps in the evolution of the Sant'Arcangelo Basin. Basin-scale hinterland-verging thrust faults and folds controlled the development of sub-basins and the progressive isolation of the Sant'Arcangelo Basin from the Ionian foredeep. The new model presented here defines the Sant'Arcangelo Basin as a triangular-shaped basin, bounded by oppositely verging thrusts. The hinterland-verging Valsinni thrust anticline limited its eastern margin and exerted a major control on the basin evolution.