Tethyan Permian-Mesozoic evolution in the Sicily Pelagian continental margin (Central Mediterranean).

Abstract

Palinspastic backstripping of the Sicily Neogene-Quaternary orogenic wedge helps to envisage the original pre-orogenic paleogeography of the Pelagian Promontory including a N-Africa restoration to its Permian position. The Sicily regional setting has been imaged, on a recently acquired crustal seismic transect [Catalano et al., 2013], as an Iblean-Pelagian crustal foreland monocline and its northward-dipping extension which underlies the whole Orogen. The tectonic units involve the deformation of rock successions formerly located (before Corsica and Sardinia rotated away from southern France) in a space now occupied by the Tyrrhenian Sea. The Sicilian FTB was formed in a complex subduction roll-back of a continental/transitional African/Pelagian slab which was associated with the counter-clockwise rotation of Corsica and Sardinia, and the clockwise rotation of the now allochthonous basement units of the Calabria/Kabylian backstop during the Neogene. The Iblean-Pelagian crustal foreland is attached to the Africa and bounded to the east by the Ionian crust. Crustal/sub-crustal reflectivity features image, on the re-processed transect [Valenti et al., 2014], brittle deformation in the upper crust and sub-horizontal sub-Moho events, both spatially associated with the “layered” lower crust, suggesting extensional geodynamic processes with associated magmatic underplating of the Sicilian lower crust. It opens new perspectives on the Late Paleozoic-Early Mesozoic paleogeography of Sicily and on the inherited crustal pattern of the central Mediterranean area. The Permo-Early Mesozoic stratigraphy implies that this region could belong either to the passive margin of the Permian ocean or to a Permian rift with thinned (?) continental crust connecting Sicily to the Jeffara (Tunisia) zone. Above the probably already stretched continental crust, during the early Mesozoic, a wide carbonate platform (including the now stacked Panormide, Trapanese-Saccense and the autochthonous Iblean), flanked to the (present-day) east-north-east by a subsident attenuated crust deep-water margin (Imerese and Sicanian domains), developed, forming, on the whole, the Pelagian continental margin. During the early Mesozoic, to the east of Sicily, the Ionian Sea probably opened in the wake of the northward drifting Adriatic Plate [e.g. Stampfli & Borel, 2004 and references]. The present-day SE-NW trending location of the Ionian debated oceanic crust [Roure et al., 2012] and the Sicilian and Southern Apennines Mesozoic paleogeography suggest an oceanic crust could continue west-northwestward beyond the present Straits of Messina, separating the Adriatic platform from another carbonate domain (the Iblean-Pelagian platform) which was located to the south of the reconstructed position of Corsica and Sardinia, immediately to south of the southern France. [Catalano et al., 2001; Stampfli & Borel, 2004].

Our results aim to provide important clarifying background to document rift phases that preceded the opening of Ionian Sea and possibly the connected Ligurian-Sicilide-Lagonegro Sea that led to the separation of the Pelagian margin from the Adriatic platform and its allochthonous northern continuation, i.e the Eastern Alpine thrust sheets. Consistent reconstructions would also be required for all major counter-clockwise rotated tectonic units of the Southern and Central Apennines. Integrating these two sets of paleogeographic reconstructions will probably lead to defining problems that will require additional detailed structural studies.

AAPG Datapages/Search and Discovery Article #90226 © 2015 European Regional Conference and Exhibition, Lisbon, Portugal, May 18-19, 2015