Continental collision history from arenites of episutural basins in the Northern Apennines, Italy

Integration of sandstone petrography, sedimentology, stratigraphy, and stru ctural and paleogeographic restorations of elastic sediments deposited in e pisutural basins has allowed us to unravel the collisional history of the N orthern Apennines from middle Eocene to Holocene time, as illustrated in se ven paleogeographic maps. The episutural successions were deposited in two types of basins. 1. Late Eocene-early Oligocene basins perched on deformed Ligurian units (o phiolites and their sedimentary cover) of the southwestern side of the Alps (i.e., part of the future northern Apennine accretionary wedge). In these basins, provenance evolved from an extrawedge north-to-south supply from th e Austroalpine (Adriatic) continental block to an intrawedge supply with pr ogressive unroofing of the collisional tectonic stack composed of Ligurian units plus minor high-pressure-low-temperature metamorphic units (Pennidic units). These basins developed after the middle Eocene continental collisio n between the Adriatic margin and the southern European margin, a period do minated by magmatism, uplift, and block faulting of the Pennidic-Ligurian o rogen. 2. Late Oligocene-Holocene basins formed on top of the migrating Apenninic orogenic wedge, which was progressively thrust onto the Adriatic margin, wh ere thick, turbiditic successions were being deposited on the foreland, San dstone composition is characterized by an overall increase in detritus from Pennidic units both up-section and from south to north and by detritus rec ycled from older sedimentary units and their Ligurian substratum. These bas ins developed during continental subduction of the Adriatic plate toward th e west underneath the Corsica-Sardinia block coupled with extension in the future western Mediterranean area. Sedimentation patterns indicate that paleobathymetry and source rocks were markedly different north and south of the Val Secchia line, a structural li neament that does not correspond to a present day observable structure acro ss the Apennines.