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Based on new CROP seismic data, integrated with other geological-geophysical information, an evolutive lithospheric tectono-dynamic reconstruction of the Sicilian region and its Tyrrhenian margin has been done with innovative results. The data and conclusions presented here are supported not only by the here annexed and described sections, but also by relevant results from the organic ensemble of the whole interpreted CROP dataset. The preorogenic (Lower Cretaceous) paleogeographic framework of the central Mediterranean, now much better constrained by direct CROP data, consisted of two inter-communicating ocean basins: the Alpine and Ionian Neotethys. These basins were interposed between Europe and Africa--Adria, and between the Adria and the Africa the Ionian one. Downward extension of the geophysical imaging to the upper mantle allowed a better understanding of the complex evolution of this wide Mediterranean area. One of the most significant and helpful new results obtained is represented by clear seismic imaging of the upper Ionian slab buried beneath a stack of allochthonous crustal units colliding with the paleo-Sicily (African) slope. Such a situation, previously postulated in uncontrolled, extrapolated models, is now well defined. The stratigraphic and structural data collected onland, and integrated with subsurface geophysical and borehole data allow us to reconstruct the geological setting of Sicily. The Foreland Domain is represented by the undeformed portion of the Pelagian block, exposed in the Hyblean plateau and the Sciacca platform. From the Late Miocene, the detachment of inner edge units gave rise to Triassic-through-Miocene carbonate platform imbricates: the Pelagian--Sicilian Thrust Belt. This external thrust system is exposed only in western Sicily. The lowermost carbonate platform imbrication reaches the surface in the area north of Sciacca as a large ramp anticline involving Early Pliocene deposits. Geoseismic data show that the wedge of Meso-Cenozoic carbonate platforms is underlying a tectonic melange, mainly composed of Oligo-Miocene Numidian nappes. The thrust belt outcrops in the structural highs of Rocca Busambra and M. Kumeta ("M. Alpi-like thrust"). The deep-seated thrust belt is tectonically overlain by "roof thrust systems", composed of the Apenninic fold-and-thrust belt, originating from the deformation of both basinal and carbonate platform Mesozoic-Tertiary deposits overlain by crystalline units (Calabrides). The lowermost tectonic units of the chain are the Ionides (the Sicanian, Imerese, M. Judica basinal carbonate and siliceous thrust sheets). They deposited in the Ionian Tethys basin and are overridden by the Panormides. A large nappe, composed of Permo-Triassic rocks grading up into a Mesozoic-Paleogene carbonate sequence, the Lercara unit, lies widely over the Middle-Late Miocene top levels of the Sicanian and Imerese units. Therefore it is thought to pertain to a palaeogeographical area originally located along the margin of the Ionian Tethys, and provides useful information about the opening of this Neotethyan Sea. The Ionides are composed of complex basinal thrust sheets, overriding the Late Miocene--Pliocene top levels of the Sicilian--Pelagian Thrust System (Tyrrhenian stage). Sicily is characterized by a huge volume of Late Oligocene--Early Miocene Numidian Flysch, deriving from the substratum of the Panormides. The Numidian Flysch is overlain by the Alpine Tethydes, widely displaced as far as the frontal wedge of the chain. All reconstructed seismogeological sections show coherent results and thus allow us to invert in a regionally well-constrained manner the tectonic processes which occurred.… [ABSTRACT FROM AUTHOR]

Using CROP geophysical data integrated with other information, a new lithospheric seismogeological section across the Southern Apennines, from the Marsili Basin in the Tyrrhenian Sea to the Adriatic coast of Apulia, has been reconstructed. This section provides a clear regional deep subsurface imaging of the tectono-stratigraphy, and interpretation of the CROP network allows us to propose a new, much more constrained, geodynamic model. Across the Southern Apennines thrust belt, from the young (Quaternary) back-arc basin of Marsili to the Apulian Permo-Mesozoic foreland, various tectono-stratigraphic units with different histories are imaged and described. The first part of the paper comments on the geological data obtained by geological fieldwork carried out mainly in the Lucania sector, integrated with available subsurface data (seismic, borehole); the second presents the new interpreted crustal-lithospheric seismogeological section. From the Tyrrhenian ocean basin to the outerward undeformed Apulian foreland, the Southern Apennine thrust belt is formed by: (a) a deformed European crustal fragment, detached from the Corso-Sardinian block in the Tyrrhenian stage; (b) a deformed crustal block of the Etrurian Promontory (NW Adria corner), which collided with the Apulian slope, whose Mesozoic cover gave rise to the Apennine platform thrust-sheets. Between (a) and (b), Alpine Tethydes Units (Ligurides), detached from subducted Alpine Tethys slab, were closed in the Balearic stage; (c) A wedge of Ionian Tethydes or Ionides (Lagonegrese) stripped off the subducted Ionian slab and thrust obliquely onto Apulia (over Lower Pliocene cover) in the Tyrrhenian stage; (d) two main families of flysch: the Albidona group and the Gorgoglione more external flysch group, plus the Numidian flysch derived from displaced Paleozoic basal quartzites of denuded Adria--Africa zones (Etrurian and Panormid promontories); and e) rooted or severely displaced buried thrust structures of the Apulian platform. A well-constrained description of the tectono-stratigraphy of the units which compose the allochthonous nappe is given, and some geological sections are illustrated. The field geology with careful biostratigraphic control shows that the units of the Southern Alpine chain (SAC), deriving from sedimentary sequences originating in the Alpine Tethys realm, started to deform in the Late Oligocene and continued later on involving the external domains. The reconstructed lithospheric seismogeological section exhibits clearly that two main tectonostratigraphically distinct complexes are present on the onshore Southern Apennines thrust belt: (1) a buried Apulian platform, deformed by Pliocene compressive tectonics, which produced folds and reverse faults, mostly of relatively moderate horizontal displacements, where a major part of the thrust features remain substantially rooted; (2) a strongly tectonized composite nappe over Apulia, made up of allochthonous units and internalexternal- reworked flysch. A stack of allochthonous crustal blocks colliding with the Apulian slope on the Tyrrhenian side characterizes the Tyrrhenian margin. Careful interpretative seismic reprocessing allowed us to obtain for the first time a clear seismic imaging of the subducted Ionian slab, the buried slope of Apulia on the Tyrrhenian side, and the stacked allochthonous crustal blocks. From the Marsili basin to the Apulian foreland, the major crustal features have been identified and their tectono-stratigraphy outlined. On the Apulian slope, a previously formed tectonic stack of two crustal fragments, which took part in the closure of the interposed Alpine and Ionian Neotethyan oceans, collided. The Corso-Sardinian block in the Balearic stage (Late Oligocene--Early Miocene) collided with the northwestern Adria margin with thrusting of the Alpine Tethydes over Adria (Etrurian Promontory).… [ABSTRACT FROM AUTHOR]