The Liguride Complex of Southern Italy —a Cretaceous to Paleogene accretionary wedge

Abstract

The ophiolite-bearing allochthonous flysch (Liguride Complex) of the Southern Apennines, Italy, has traditionally been divided into two tectonic units: the metamorphic Frido Unit and the unmetamorphosed Cilento Unit. The two units have hitherto been considered to derive from two distinct paleogeographic domains; however, the identification of Cilento Unit sediments within Frido Unit successions implies that the sediments of both units were coeval deposits within the same sedimentary basin. Cilento Unit sediments also occur as the sedimentary cover of kilometre-scale oceanic slices within the Liguride Complex indicating deposition on oceanic basement and not continental basement as was previously considered. Thrust transport directions and sediment provenance indicate that during Late Jurassic time this ocean basin lay to the east of the Calabrian terrain and to the west of Apulia, Calabria and Apulia representing the European and African margins of Neotethys respectively. Northwestwards subduction of oceanic crust beneath the Calabrian terrain from Late Cretaceous time onwards produced an accretionary wedge which was later emplaced onto the Apulian margin during the Burdigalian collision of Calabria and Apulia. The Liguride Complex represents the obducted remains of this accretionary wedge. This interpretation contains three important implications for pre-Tertiary plate tectonic reconstructions of the western Mediterranean region, these are: 1. (1) The Calabrian continental terrain formed part of the Iberian Plate on the north margin of Neotethys, this may have implications for the former location and continuation of the North Pyrenean Fault. 2. (2) The existence of a continuation of the “Eo-Alpine” belt through Calabria and the Kabylies is placed in doubt thus requiring only one, constant polarity (NW-dipping) subduction direction to explain the structures now seen in these regions. 3. (3) The existence of a transform fault between the Europe-vergent structures of Corsica and the Africa-vergent structures of Calabria. This transform must have been active from at least Late Cretaceous time in a position now occupied by the Tyrrhenian Sea.