Abstract Detailed geological mapping and new stratigraphic and structural data collected in the Lucania area of the southern Apennines allowed us to assess the deformation history of Il Monte–Corleto Perticara zone, in the High Agri Valley (Lucanian Apennines, southern Italy) where red and green shales (known as Argille Varicolori or Argille scagliose) crop out. Our observations suggest that: (1) ‘chaotic’ facies within the Argille Varicolori may be attributed to a broken formation generated by overthrusting of Apenninic Platform units onto already deformed Lagonegro basin strata; (2) gravity sliding phenomena at the thrust front enhanced the development of debris flow and the emplacement of olistostromes at distances of up to tens of kilometres from the leading edge of the Apenninic Platform thrust; (3) the above processes probably ended in mid-Miocene time, as suggested by observed structural and stratigraphic relationships among accreted terranes and synorogenic deposits. The evolutionary model envisaged here could also be relevant in other active convergent zones, where seismic and drilling data are sparse, and in subaerial fossil margins where broken formations occur.

Abstract Radiolitids with a long cylindrical right valve and thin compact outer shell layer have frequently been reported in upperTuronian-Santonian (Upper Cretaceous) carbonate-platform sequences from the central Mediterranean area. Analysis of morphology and structure of species of Biradiolites, Radiolites , and Distefanella from different stratigraphic horizons and sedimentary environments in thecentral Apennines, Italy, indicate that these characteristics are a consequence of the fast growth rate (up to 40 mm/year) that is related tothe sediment accumulation rate. Constructional morphologies of the right valves of the studied species are similar but the left valves are different. Right valves may bevery elongate, erect, straight or multi-geniculate, thin-shelled, and formed almost entirely of compact structure. The left valves are flat, oreven slightly concave, and the teeth and myophores are weak in the studied species of Biradiolites and Radiolites , but in Distefanella the leftvalve is cupuliform and provided with robust teeth and myophores. The studied species of Biradiolites and Radiolites are usually represented by monotypical to oligotypical communities in low-energy tomoderate-energy mud-supported deposits, with fast growth rates indicating moderate to high sedimentation rates, in inner-platform tolagoon or peritidal environments. The species of Distefanella generally occur as diversified assemblages in moderate-energy to high-energy, grain-supported deposits with fast growth rates indicating high sediment accumulation rates in platform-margin to gently dipping slopeenvironments, dominated by well diversified rudist communities. The asymmetric distribution of the considered taxa in central Italy carbonate successions follows a pattern that is related to thewestward-flowing Tethys Circumglobal Current, which formed an anticlockwise gyre in the Mediterranean Tethys and different paleo productivities. Slender radiolitid biofacies (SRB) with Distefanella spread over the presumably windward platform margin thattoday crop out along the Apennine chain facing the Adriatic side (i.e., the Ocre Mountains and the Matese Mountains in the ApenninePlatform and along the Majella Mountain in the Apulia Platform). In contrast, SRB with Radiolites and Biradiolites should characterizethe leeward, inner-platform and slope side of the Apennine Platform that today crop out along the Lepini-Ausoni-Aurunci Mountains, facing westward toward the Tyrrhenian Sea.

Geological analysis of geophysical data obtained by the interpretation of crustal profiles indicates that in the central Mediterranean region the following structural domains can be distinguished: the foreland domains, an orogenic belt, and the Corsica-Sardinia block. The foreland domains are represented by two continental blocks, the Apulian block to the north and the Pelagian block to the south, belonging respectively to the Adria and to the Africa plates, separated by the oceanic crust of the Ionian Sea. The orogenic belt is located between two oceanic crusts: the old Ionian crust, at the present time subducting beneath the Calabrian arc, and the new crust of the Tyrrhenian Sea. The orogenic belt is represented by a multilayer allochthonous edifice composed of the Calabride chain, which tectonically overlies the so-called Apenninic-Maghrebian chain, which in turn is overthrust onto the upper Miocene and Pliocene top levels of a deep-seated thrust system that originated from the deformation of the innermost carbonates of the Apulian and Pelagian blocks (the external thrust system). The Calabride chain is composed of crystalline nappes originating, since the Eo-Oligocene, from the delaminated margin of the Europe plate. The Apenninic-Maghrebian chain tectonic units derive from the orogenic transport during Oligo-Miocene times of sedimentary sequences deposited in paleogeographic domains located between the Europe and the Afro-Adria plates. These units are composed of meso-Cenozoic shallow-water carbonate successions detached from a continental type of crustal sector named here the Panormide-Apenninic block. This is now recognizable by means of seismic lines shot in the Tyrrhenian off-shore of the southern Apennines and northern Sicily. The meso-Cenozoic basinal units that constitute the Apenninic-Maghrebian chain can be distinguished into two main groups of sequences, originally located on oceanic crusts separated by the Panormide-Apenninic crust: the external ones (Ionides) related to an original basin belonging to part of the Ionian paleo-basin involved in the orogenesis (Lagonegro, Imerese, Sicanian, and Monte Judica units) and the internal ones ascribed to the Alpine Tethys (Liguride-Sicilide units). The previously described allochthonous edifice is characterized by thin-skinned tectonics and represents a roof thrust system resting on the external thrust system, which derived from thick-skinned tectonics that produced folds and reverse faults with relatively moderate horizontal displacements. The external thrust system developed from late Miocene times, contemporaneously with the opening of the Tyrrhenian basin, and is named the Apulian thrust system in southern Italy and the Pelagian-Sicilian thrust belt in Sicily. The crustal sections of the CROP project (Deep Seismic Exploration in the Central Mediterranean and Italy) allow us to distinguish the thickness and distribution of the crusts in this area of the Mediterranean Sea, and they confirm that the foreland continental blocks, the Apulian and the Pelagian blocks, are separated by the Ionian oceanic crust. Both the foreland blocks extend below the orogenic belt, reaching the Tyrrhenian margins, with a gradual thinning and a transition to a Paleo-Ionian slab, probably not active at present time, from which the Ionides detached and overrode the external thrust system. The seismogeological data indicate the presence of a continental block, original basement of the Panormide-Apenninic platforms, that took part in the closure of the sectors of the Paleo-Ionian Sea interposed between the Panormide-Apenninic crust and the Pelagian and Apulian blocks. At the present time, it is colliding with the foreland blocks. Thus, this has been identified as collisional crust. The geologic evidence of this collisional stage is manifested in the northwest-southeast-oriented South Tyrrhenian system, which is characterized by dextral faults affecting both off-shore and on-shore areas of Sicily. A mirrorlike sinistral fault system occurs in the southern Apennines. Interpretative seismic reprocessing has permitted clear seismic imaging of the subducted Ionian slab. The distribution of the earthquakes transversally and longitudinally indicates that the slab is narrowing in a vertical direction; thus, at present, the active slab is limited to a short segment between northeastern Sicily (the Vulcano line) and southern Calabria (the Catanzaro line). To the west and to the northeast of these lines, a collisional setting can be recognized. The geological and geophysical data and the volcanological characteristics of the study area permit us to restore the paleogeographic and paleotectonic setting and have allowed us to recognize three orogenic stages: the Eo-Alpine, which originated during Cretaceous–Eocene times but is less evident in the study area; the Balearic stage (late Oligocene–early Miocene), in which the Corsica-Sardinia block collided with the Adria-Africa margins with thrusting of the Alpine Tethydes over Panormide units; and the Tyrrhenian stage (middle Miocene to present), when the onset of the Tyrrhenian back-arc basin occurred and the collisional crust followed the Ionian slab retreat, closing the interposed basin with tectonic transport of the Ionian ocean cover (the Ionides) over the foreland blocks.

ABSTRACT Deposition of Upper Cretaceous carbonate sequences in central Italy (westcentral Latium) appears to be directly related to the tectonic evolution of an epioceanic Central Apennine Platform. From early Cenomanian to late Senonian time organic buildups, along with skeletal shelf-edge deposits, were laid down along the present northwestern margin of the Lepini Mountains, and the southern portion of the Prenestini Mountains. These sediments overlie rocks of the Cretaceous (Aptian-Albian) restricted platform facies. Late Cretaceous shelf-edge deposits are characterized by sequences of rudistid and coral communities laid down within varied depositional settings. The rapid development of these organic communities along a linear tectonically induced shelf-margin caused pronounced increases in the production of bioclastic debris, and the distribution of these sediments both on the marginal slope and in the back-reef areas. This bioclastic debris accumulated in offshore shoals and in tidal banks connecting patch-reefs and organic banks. The continued presence during Cenomanian time of a linear shelf-edge organic buildup complex appears to have been the dominant controlling factor in regards to inner-platform sedimentation. Here, nerineids (gastropods), ostreids (pelecypods), and radiolitid rudistid pelecypod communities, occurring in muddy skeletal wackestones, suggests deposition within both open marine shelf-lagoons and back-reef environments. In addition, the presence of mudstones (some laminated), and peloidal grainstones containing benthonic microfossils, suggests somewhat sheltered shelf-lagoonal to tidal flat depositional settings. Differential tectonism during Turonian time, causing regional sea level fluctuations, produced varied facies patterns due to changes in water circulation and sedimentation over the shelf area. An open marine shelf-lagoon facies with abundant microfossils was widespread during this time. Conditions of sea level fluctuations and influx of clean marine waters onto the platform led to the development of rudistid banks and winnowed skeletal sands along the platform-margin. The tectonism of early Turonian time caused subaerial exposure of the western portion of the Rocca di Cave area, followed by sedimentary progradation. Various changes in overall regional bathymetry, with resultant restriction in water circulation, increased during Senonian time. Isolated platform areas became outer “highs” surrounded by deeper water, although these “highs” were partially covered by shoaling transgressive sediments (Rocca di Cave). In some instances the shelf area was drowned bringing shelf-margin facies into former platform areas, and forming organic shoals and barrier islands during repeated progradation (Lepini Mountains).

Abstract Mike Coward’s seminal work on strain within thrust sheets clearly showed how understanding crustal scale deformation associated with orogenesis requires a knowledge of both: (1) deformation associated with major thrusts and/or high-strain shear zones, and (2) finite strain states within the (usually large) surrounding rock volumes. In this study, the strain variations within a major, far-travelled thrust sheet internally deformed at very low-temperature, sub-metamorphic conditions, are analysed. The studied rocks belong to the thick carbonate succession of the Apennine Platform, which constitutes a major tectonostratigraphic unit of the southern Apennines. Finite strain analysis, besides quantifying the relative importance of different deformation mechanisms and the role of matrix and object strain, points to the existence of both vertical and horizontal strain gradients. These are probably controlled by both heterogeneous shear deformation associated with NE-directed tectonic transport and sedimentary carbonate facies distribution. The relative position with respect to the main overlying tectonic contact and the occurrence of a barrier to fluid flow, represented by siliciclastic beds located at the top of the carbonate succession, are also likely to have played an important role in the development of the observed regional strain gradients. On the metre scale, deformation appears to be partitioned into domains of quasi-coaxial and dominantly non-coaxial strain, controlled by different degrees of strain localization in texturally different stratigraphic layers.