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Mulitbeam swath bathymetry and reflection seismic data image large submarine landslide complexes along ocean margins worldwide. However, slope failure initiation, acceleration of motion and mass-transport dynamics of submarine landslides, which are all key to assess their tsunamigenic potential or impact on offshore infrastructure, cannot be conclusively deduced from geometric expression and acoustic characteristics of geophysical data sets alone, but cores and in situ data from the subsurface are needed to complement our understanding of submarine landslide dynamics. Here we present data and results from drilling, logging and coring thick mass-transport deposits (MTDs) in the Nankai Trough accretionary prism during Integrated Ocean Drilling Program (IODP) Expeditions 333 and 338. We integrate analysis on 3D seismic and Logging While Drilling (LWD) data sets, with data from laboratory analysis on core samples (geotechnical shear experiments, X-ray Computed Tomography (X-CT), Scanning Electron Microscopy (SEM) of deformation indicators, and magnetic fabric analysis) to study nature and mode of deformation and dynamics of mass transport in this active tectonic setting. In particular, we show that Fe-S filaments commonly observed on X-ray CT data of marine sediments, likely resulting from early diagenesis of worm burrows, are folded in large MTDs and display preferential orientation at their base. The observed lineation has low dip and is interpreted as the consequence of shear along the basal surface, revealing a new proxy for strain in soft sediments that can be applied to cores that reach through the entire depth of MTDs. Shear deformation in the lower part of thick MTDs is also revealed from AMS data, which ¿ in combination with other paleo-magnetic data - is used to reconstruct strain and transport direction of the landslides

One hundred years ago, in 1919, the British geologist Edward Greenly coined the term “mélange”, abbreviation of “autoclastic mélange”, in describing a tectonically disrupted and internally strained phyllite-sandstone succession in the Mona Complex (Gwna Group) in Anglesey, north Wales (Greenly, 1919). Since this first definition, and after Hsü (1974), the term “mélange” has been extensively used to describe the occurrence of chaotic rock assemblages in orogenic belts and ancient subduction-accretion complexes, and later extended to other geodynamic environments such as collisional and intra-continental tectonic settings, including rifting and passive margin evolution, and strike-slip tectonic settings. This Special Issue of Gondwana Research, which is published to celebrate the 100th anniversary of the inception of the term “mélange” and concept in the geological literature (Greenly, 1919), is aimed at exploring and documenting such open problems and further ways of research revolving around mélanges, at various scales and in different tectonic settings and ages, through multi-disciplinary case studies from around the world.

A significant part of melanges recognized in exhumed convergent margins around the world has been recently documented to have chiefly originated from masse transport and subsurface remobilization and disruption (i.e. melanges, from sedimentary and mud–serpentinite diapiric processes and from in situ fluidification–disruption). Tectonic and/or sedimentary processes occurring during subsequent multiple deformational events of convergent margin evolution commonly overprint and significantly rework the primary (sedimentary or diapiric) melange fabric, forming polygenetic melanges. This ultimately complicates their distinction from true tectonic melanges, masking part of the recorded tectono-sedimentary evolution of the associated convergent margin. The contributions gathered in this thematic collection explore with different approaches (from field structural and stratigraphic observations to geophysical analyses) different types of polygenetic melange, at various scales, around the world. These studies conclude that the understanding of this type of melange may provide crucial insights for a more detailed interpretation of the evolution of ancient and modern convergent margins, and of processes and mechanisms triggering potential natural hazards (earthquakes and tsunamis). Case studies include the Apennines in the Central Mediterranean region, the Carpathians in Central Europe and the Nankai Prism in Japan. Thematic collection: This article is part of the ‘Polygenetic melanges: a glimpse on tectonic sedimentary and diapiric recycling in convergent margins’ collection available at https://www.lyellcollection.org/cc/polygenetic-melanges

Upper Lutetian-Bartonian sedimentary mélanges, corresponding to ancient mud-rich submarine mass transport deposits, are widely distributed over an area c. 300 km long and tens of kilometres wide along the exhumed outer part of the External Ligurian accretionary wedge in the Northern Apennines. The occurrence of methane-derived carbonate concretions (septarians) in a specific tectonostratigraphic position below these sedimentary mélanges allows us to document the relationships among a significant period of regional-scale slope failure, climate change (the Early and Mid-Eocene Optimum stages), the dissociation of gas hydrates and accretionary tectonics during the Ligurian Tectonic Phase (early-mid-Lutetian). The distribution of septarians at the core of thrust-related anticlines suggests that the dissociation of gas hydrates was triggered by accretionary tectonics rather than climate change. The different ages of slope failure emplacement and the formation of the septarians support the view that the dissociation of gas hydrates was not the most important trigger for slope failure. The latter occurred during a tectonic quiescence stage associated with a regressive depositional trend, and probably minor residual tectonic pulses, which followed the Ligurian Tectonic Phase, favouring the dynamic re-equilibrium of the External Ligurian accretionary wedge. Our findings provide useful information for a better understanding of the factors controlling giant slope failure events in modern accretionary settings, where they may cause tsunamis.

Olistostrome and sedimentary mélange are two synonymous genetic terms referring to the “fossil” products of ancient submarine mass‐transport processes exhumed in orogenic belts. Lithology, stratigraphy, lithification degree, and structural anatomy of these units reflect the synergic and combined action of different mass‐transport processes leading to composite deposits developed through multistage deformation phases. The general depositional physiography, tectonic setting, and the type, scale, and rate of slide mass transformation mechanisms during the downslope motion and emplacement and postdepositional processes are the main factors controlling the final internal anatomy of olistostromes and sedimentary mélanges. These features are commonly progressively reworked by subsequent burial, diapiric, and tectonic processes and may be eventually almost completely obliterated by metamorphic processes during orogenic belt and/or subduction complex evolution. The correct recognition of olistostromal units and their intrinsic features in different orogenic belts needs extensive and careful fieldwork and ultimately provides excellent proxies for the timing of various tectonic‐sedimentary events interacting during the Wilson cycle. The basic concepts of structural geology, sedimentology, stratigraphy, and basin analysis should be jointly applied in studying the internal structure, lithological arrangement, and formation-deformation mechanisms of olistostromes and sedimentary mélanges.

The Casaglia-Monte della Colonna is one of the best exposed “fossil” mass-transport complex (MTC) cropping out in a foredeep succession exhumed in a mountain chain and represents a unique opportunity to study an internal architecture resulting from the (geologically) simultaneous collapses of an accretionary wedge front, slope, and basin plain deposits. The high variety of internal structures and the different MTC-substratum interactions depend on the geometry of MTC basal contact and the provenance of the remobilized sediments. In the 20 years from our first studies on this MTC, the better condition of some outcrops and the advances in methodological and interpretative tools enable us to provide an update scenario, with more details on the internal structures and a better comprehension of the complex interactions with the substratum.

Multiple episodes of deformation during the tectonic evolution of orogenic belts and ancient subduction-accretion complexes cause obfuscation of primary block-in-matrix fabric of melanges, and thereby making the recognition of their tectonic, sedimentary or diapiric origin difficult. Here we present a comprehensive overview and synthesis of a diverse set of field-based stratigraphic and structural criteria, which are at the base of geological mapping rules, to differentiate between various melange types, developed by disparate geological processes and mechanisms. We first define the current concepts of melange and melange nomenclature, and describe the most diagnostic features of tectonic, sedimentary and diapiric melanges at different scales. We discuss some of the main issues complicating the application of these diagnostic criteria, such as: (i) similarities between the block-in-matrix fabric of different melange types formed in partially lithified sediments at shallow structural levels, (ii) transformation of fabric elements with increased depth due to tectonic reworking and recrystallization processes, (iii) significance of “exotic” versus “native” blocks in melange matrix, and (iv) age relationships between blocks and matrix in a melange. We introduce two additional criteria in approaching these complexities and in recognizing different processes of polygenetic melanges formation in the field when primary diagnostic fabrics were reworked by multiple deformational events. These new criteria are based on (i) the coherence between lithological compositions of melange components (blocks and matrix) and characteristics and tectonic evolution of the geodynamic setting of their formation (“tectonic environment criterion”), and (ii) specificity and kinematic coherence in the distribution of deformation between blocks and the matrix (“deformation criterion”). The discussed diagnostic criteria can be applied to all field-based investigations of melanges and broken formations in orogenic belts and exhumed subduction-accretion complexes around the world, regardless of their location, age, and tectonic history.

We present a critical appraisal of the role of subducted, medium (10-1000 km(2)) to giant (>= 1000 km(2)) and heterogeneous, mud-rich mass transport deposits (MTDs) in seismic behavior and mechanisms of shallow earthquakes along subduction plate interfaces (or subduction channels) at convergent margins. Our observations from exhumed ancient subduction complexes around the world show that incorporation of mud-rich MTDs with a "chaotic" internal fabric (i.e., sedimentary m langes or olistostromes) into subduction zones strongly modifies the structural architecture of a subduction plate interface and the physical properties of subducted material. The size and distribution of subducted MTDs with respect to the thickness of a subduction plate interface are critical factors influencing seismic behavior at convergent margins. Heterogeneous fabric and compositions of subducted MTDs may diminish the effectiveness of seismic ruptures considerably through the redistribution of overpressured fluids and accumulated strain. This phenomenon possibly favors the slow end-member of the spectrum of fault slip behavior (e.g., Slow Slip Events, Very Low Frequency Earthquakes, Non-Volcanic Tremors, creeping) compared to regular earthquakes, particularly in the shallow parts (T

In order to investigate in detail the effects of dehydration and grinding on the mechanical shear behaviour of Ca-rich montmorillonite, a cycle of specific experimental shear deformation tests were performed on five typology of samples, preliminary controlled by thermal analysis (TG, DTA) and X-ray diffraction (XRD): (1) a natural Ca-montmorillonite containing about 5% of adsorbed water; (2) the same montmorillonite heated at 80 °C for 2 h to remove only the adsorbed water; (3) up to 250 °C for 2 h to remove also the interlayer water; (4) up to 340 °C for 2 h to complete the removal of interlayer water and start to introduce thermo-structural defects, and (5) the starting natural Ca-rich montmorillonite after hard ball-milling for 20 h to induce mechanical deformation and structural defects in the TOT layers. The five typologies of samples have been tested by a specifically designed and built shear box apparatus, under about 20 MPa condition of normal pressure. All samples, before and after the shear test, have been analysed by Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and XRD. A theoretical mechanical analysis based on the Maxwell model is proposed to explain the τ(e) and τ( e ) shear behaviour of the effects of the different type of dehydration and deformation of the material, that was finally discussed in the context of the microstructural OM, SEM and XRD data.

The Paleogene carbonate “megabreccia” units of the Friuli Basin are composite deposits produced by catastrophic shallow-water carbonate platform collapses re-deposited in relatively deep-water inner foredeep settings developed at the front of the advancing Dinaric thrust system. These thick, basin-wide mass transport deposits (MTDs) record the catastrophic emplacement of bipartite slide masses, comprising a lower coherent/cohesive blocky flow and an upper grain/turbulent flow. We here present the results of micro- to outcrop-scale structural analyses, constrained by stratigraphic and sedimentologic observations, performed to identify the internal deformation mechanisms and the emplacement processes of four of the largest MTDs exposed in two large three-dimensional outcrops: the Vernasso (NE Italy) and Anhovo (W Slovenia) open-pit quarries. Our results reveal a variety of primary (sedimentary) soft sediment deformation structures testifying fluid overpressure conditions within the brecciated, fine-grained matrix that sustain, intrude and surround slide blocks and clasts. Meso-scale structural analyses unraveled paleo-transport directions toward the N for the Vernasso quarry and toward the S for the Anhovo quarry. This suggests a forced propagation of the mass transport events controlled by the shape of basin, and reinforces the interpretation of different source areas related to multiple collapses from a carbonate platform rimming the southeastern tip of the basin. These units are thought to represent exhumed fossil examples of the MTDs extensively mapped in the present-day, carbonate-dominated continental margins, and thus, considered as reliable analogues for integrated studies.

The terms melange and broken formation have been used in different ways in the literature. The lack of agreement on their definition often leads to confusion and misinterpretations. An evaluation of the various uses of these terms allows us to consider several types of chaotic rock bodies originated by tectonic, sedimentary and diapiric processes in different tectonic settings. Our review of stratal disruption and mixing processes shows that there exists a continuum of deformation structures and processes in the generation of melanges and broken formations. This continuum is directly controlled by the increase of the degree of consolidation with burial. In tectonically active environments, at the shallow structural levels, the occurrence of poorly consolidated sediments favors gravitational deformation. At deeper structural levels, the deformation related to tectonic forces becomes gradually more significant with depth. Sedimentary (and diapiric) melanges and broken formations represent the products of punctuated stratal disruption mechanisms recording the instantaneous physical conditions in the geological environment at the time of their formation. The different kinematics, the composition and lithification degree of sediments, the geometry and morphology of the basins, and the mode of failure propagation control the transition between different types of mass-transported chaotic bodies, the style of stratal disruption, and the amount of rock mixing. Tectonically broken formations and melanges record a continuum of deformation that occurs through time and different degrees of lithification during a progressive increase of the degree of consolidation and of the diagenetic and metamorphic mineral transformation. Systematic documentation of the mechanisms and processes of the formation of different broken formations and melanges and their interplay in time and space are highly important to increase the understanding of the evolutionary history of accretionary wedges and orogenic belts. (c) 2012 Elsevier B.V. All rights reserved.

Understanding the factors that contribute to anisotropic slopes instability provides important information for safe mining operations in flysch-type units. This work presents the results of sedimentological and structural analyses performed in the Anhovo Quarry (Western Slovenia), where carbonate-rich material is excavated from exhumed mass transport deposits (MTDs), generated by submarine landslides during late Paleocene. The architecture of mine design presents major challenges in terms of ideal configuration for optimized mining processes in one the largest MTDs, the Rodez Unit. A gradual increase in complexity of the slope failure mechanism is associated with different localized degrees of lithification and diagenesis depending directly on the mass transport processes. An estimation of the stability of the quarry walls is therefore based on the correct understanding of the distribution of structural features and anisotropies caused by the depositional characters of the MTD, such as paleo-transport directions, erosive potential and relationships with the basin physiography. Quarry operation planning in MTDs requires a multilayered approach for the geomechanical stability analysis, especially in terms of genesis, diagenesis, and anthropogenic activity. .

© 2014 © 2014 Taylor & Francis. In the Northern Apennines of Italy, mud-rich olistostromes (sedimentary mélanges) occur at different stratigraphic levels within the late Oligocene-early Miocene sedimentary record of episutural/wedge-top basins. They are widely distributed along the exhumed outer part of the Ligurian accretionary complex, atop the outer Apenninic prowedge, over an area about 300 km long and 10-15 km wide. Olistostromes represent excellent examples of ancient submarine mass-transport complexes (MTCs), consisting of stacked cohesive debris flows that can be directly compared to some of those observed in modern accretionary wedges. We describe the internal arrangement of olistostrome occurrences in the sector between Voghera and the Monferrato area, analysing their relationships with mesoscale liquefaction features, which are commonly difficult to observe in modern MTCs. Slope failures occurred in isolated sectors along the wedge front, where out-of-sequence thrusting, seismicity, and different pulses of overpressured tectonically induced fluid flows acted concomitantly. Referring to the Northern Apennines regional geology, we also point out a gradual lateral rejuvenation (from late Oligocene to early Miocene) toward the SE and an increasing size and thickness of the olistostromes along the strike of the frontal Apenninic prowedge. This suggests that morphological reshaping of the outer prowedge via mass-transport processes balanced, with different pulses over a short time span, the southeastward migration and segmentation of accretionary processes. The latter were probably favoured by the occurrence in the northwestern part of the Northern Apennines of major, inherited palaeogeographic features controlling the northward propagation of the prowedge. Detailed knowledge of olistostromes, as ancient examples of MTCs related to syn-sedimentary tectonics and shale diapirism, and of their lateral variations in term of age and size, provides useful information in regard to better understanding of both the tectono-stratigraphic evolution of the Apenninic prowedge and the submarine slope failures in modern accretionary wedges.

We present the integrated outcrop-geophysical study of two mass transport complexes, the exhumed Specchio unit in the Northern Apennines of Italy and the Holocene Poverty unit in the Hikurangi margin of New Zealand. The combination of micro- to meso-scale structural, stratigraphic and sedimentologic analyses carried on continuous three-dimensional outcrops, with large-scale structural and morphologic data deriving from seismic/acoustic imaging of the present-day continental margins, allow important considerations on submarine landslide processes and mechanisms through the broader (up-scaled and down-scaled) understanding of the mass transport-related structural associations. We compare the discontinuous high-amplitude, reverse-polarity reflectors observed within the Poverty with the syn-sedimentary, ductile shear zones found within the Specchio mass transport complex. The seismic signature of such structures suggests localized fluid overpressure along detachment/thrust zones due to shearing and loading of undrained, water-saturated, fine-grained material, developed along with the slide mass movement. The outcrop expression of these structures is tentatively attributed to m- to tens of m-thick shear zones comprising large amounts of sedimentary matrix which separate and accommodate the differential movements of the internal slide components (e.g. slide blocks, olistoliths). The sedimentary matrix is an unsorted, lithologically mixed medium characterized by a scale-invariant “block-in-matrix” fabric (i.e. brecciated, mud-supported), that injects, sustain and surrounds discrete slide elements (from particles to blocks) and interpreted as a hyper-concentrated (liquefied/fluidized) suspension of water and scattered sediments developed in fluid overpressure conditions. We highlight the fundamental role of shearing-related liquefaction as one of the main factors controlling slide mobility through the “lubrication” of the internal and basal friction forces. The analysis of such features can therefore provide important information for the characterization of mass transport deposits developed from potentially catastrophic, long run-out mass transport events, and consequently, to better understand their possible socio-economic impact in terms of tsunamigenic potential.

Micro-to meso-scale outcrop studies on selected field analogues allow direct calibration and testing of geophysical interpretations performed on mass transport deposits in modern continental margins, in terms of genetic processes and sliding dynamics. This comparative approach provides important information for forecasting and mitigating submarine landsliderelated geohazards. The comparison of fieldwork studies (i.e., siliciclastic, carbonate and mixed, seismic-scale Eocene-Oligocene submarine mass transport deposits of the Northern Apennines in Italy, central Pyrenees in Spain and the north-western Dinarides in Italy/Slovenia) with multibeam bathymetric, seismic and drill core data from some modern analogues (i.e., offshore of New Zealand, Japan and Svalbard in Arctic Norway) is proposed in order to upscale the outcrop observations and downscale the geophysical features. Our results show that slide mass mobility is a function of the degree of internal liquefaction/fluidization, mainly achieved at the basal sliding interval and within the slide body. This is due to undrained shearing/loading-unloading of poorly-lithified sediments, and consequent development of fluid overpressure that is able to accommodate deformations at high strain rates. Structures related to these processes are observable at all scales, and represent diagnostic criteria to recognize potentially catastrophic mass transport events.

We report here mass transport-related disruption processes and their artifacts within sedimentary m??langes. The case studies include the early Oligocene wedge-top mass transport deposits in the northern Apennines (Italy) and the Eocene foredeep carbonate megabreccias from the south-central Pyrenees (Spain). These "chaotic" units commonly share a block-in-matrix fabric expressed by variously deformed slide blocks of different size, lithology, age and shape, embedded in a fine-grained matrix. Geophysical studies of modern continental margins have characterized many of these deposits, which, however, remain still relatively poorly described in term of meso-scale characteristics. The prominent feature of the analyzed mass transport deposits is the occurrence of an unsorted, strongly mixed, relatively fine-grained clastic matrix, infilling space between large clasts and blocks. This matrix shows either fluidal structures related to simple shear, or a structureless, homogeneous fabric, both probably related to liquefaction/fluidization processes and thus, to the internal strength of the mixed lithologies. We interpreted this phase as a liquefied mixture of water and sediment, characterized by high mobility due to overpressured conditions, as evidenced by both lateral and vertical injections. On a much larger scale this kind of matrix could represent the acoustically "transparent" facies separating slide blocks of many seismic examples. The inferred generating mechanism is that of a progressive soft sediment deformation, linked to different phases of submarine landslide evolution (i.e. failure, translation, accumulation and post-depositional stages), leading to an almost complete stratal disruption of involved bedded sequences, either within the slide mass and in the underlying substrate. In this framework the down-slope movement is favored by the development of ductile, overpressured shear zones, both internally and along the basal sliding horizon. Therefore, this matrix signature represents a possible discriminating factor to separate sedimentary and tectonic m??langes within accretionary systems and, moreover, to distinguish fast- from slow-rated generating processes. ?? 2011 Elsevier B.V.

Within the Eocene-Oligocene syn-orogenic deposits of the Epiligurian succession (Northern Apennines of Italy), a field-based study of the Specchio Unit (lower Rupelian) reveals that this complex is made up of three distinct but amalgamated mass- Transport deposits (MTDs), the largest of which reaches a maximum volume of ca. 150 km3. These bodies were deposited inside the complex system of intraslope basin systems, developed atop the submerged Ligurian accretionary prism at the collision with the Adria continental plate. The MTDs originated from catastrophic retrogressive collapses starting from the upper slope and involving progressively shallow-water environments, from distal shelfal pro-delta and deltafront sediments up to proximal coastal fan-delta deposits. These recurrent and close in time, catastrophic slope failures were probably caused by tectonic and climatic triggers, such as the enhanced tectonic activity due to incipient Apenninic continental collision and the onset of harsh climatic conditions, as suggested by oxygen isotopic maxima (e.g., Oi-1a event). Although the wedge toe/foredeep systems are generally considered the principal loci of such, usually located in deep-water settings, here we stress the importance of catastrophic mass transport events also atop the wedge, in shallow-water depositional domains. Mass transport processes also have a fundamental role in reshaping the upper physiographic profile of an evolving accretionary wedge. The correct interpretation of such mass transport processes has also important implications for geohazard forecasting in modern active continental margins, for example in terms of tsunamigenic potential. © Springer Science+Business Media B.V. 2012.

Although the 1978 Penrose Conference stated that “Mélanges are mappable, internally fragmented and mixed rock bodies” formed by “tectonic movements, sedimentary sliding, or any combination of such processes”, an exclusive origin from tectonic processes is often aprioristically assumed. Due to the recent advances in the investigating methods and the increasing work of comparison between mélanges in mountain ranges world-wide, an increasingly larger number of sedimentary mélanges is recognized. Although strongly deformed by post-depositional, tectonic and/or mud-diapiric processes, these mélanges prevailingly originated from sedimentary processes. Moreover, the chaotic sedimentary bodies known as olistostromes in the literature fall inside the more general category of sedimentary mélanges, further increasing their relative abundance and diffusion. Sedimentary mélanges are prevailingly related to mass-transport processes. They often are, therefore, excellent fossil examples of mass-transport complexes (MTC), cropping out in well preserved and continuously exposures. This communication will show the results of the holistic study of both sedimentary mélanges and more classic cases of fossil MTC, with a focus on the Apennines of Italy. Fossil MTC, especially the large-scale, basin-wide ones, are complex units involving the entire spectra of mass-wasting processes and often originated by retrogressive sliding of basin margins up to the shelf. The translation of the bodies is enabled by the relative movement of discrete masses, with progressive stratal disruption of rocks/sediment involved and flow transformation. Fluid overpressure inside either diffuse or concentrated shear zones enable these movement and trigger the stratal disruption. Detailed information on internal geometry and structures and on the mechanisms of deformation can be gathered from fossil MTC, which are less readily achieved by submarine geophysical studies of modern submarine landslides. The synergic study of modern and fossil MTB should result in a better knowledge of mass-transport processes and bodies, in relation with the basin floor geometries.

In the peri-Adriatic region, mélanges represent a significant component of the Apennine and Dinaride-Albanide-Hellenide orogenic belts as well as ancient and present-day accretionary wedges. Different mélange types in this broad region provide an excellent case study to investigate the mode and nature of main processes (tectonic, sedimentary, and diapiric) involved in mélange formation in contrasting geodynamic settings. We present a preliminary subdivision and classification of the peri-Adriatic melanges based on several years of field studies on chaotic rock bodies, including detailed structural and stratigraphic analyses. Six main categories of melanges are distinguished on the basis of the processes and geodynamic settings of their formation. These mélange types are spatially and temporally associated with extensional tectonics, passive margin evolution, strike-slip tectonics, oceanic crust subduction, continental collision, and deformation. There appears to have been a strong interplay and some overlap between tectonic, sedimentary, and diapiric processes during mélange formation; however, in highly deformed regions, it is still possible to distinguish those melanges that formed in different geodynamic environments and their main processes of formation. This study shows that a strong relationship exists between melange-forming processes and the palaeogeographic settings and conditions of mélange formation. Given the differences in age, geographic location, and evolutionary patterns, we document the relative importance of mélanges and broken formations in the tectonic evolution of the peri-Adriatic mountain belts.