Marcello Schiattarella

Radiocarbon dating of active faulting in the Agri high valley, southern Italy

Abstract The high valley of the Agri River is a wide intermontane basin located in the Lucanian Apennine, southern Italy. This basin was formed during Quaternary times in the hinterland of the Neogene fold-and-thrust belt. Tectonics has strongly controlled shape, morphology and sedimentary evolution of the basin up to the present. The Agri Valley, in fact, has been hit by recurrent and large earthquakes such as the 1857 Basilicata earthquake. Pleistocene extensional tectonics is commonly envisaged as responsible for the basin evolution. On the grounds of new structural studies, indeed, the valley appears to be a more complex structure than a simple extensional graben, as traditionally assumed in the literature, or than a pull-apart basin, as suggested by some workers. The basin floor is filled by middle Pleistocene faulted alluvial deposits. A new survey has shown evidence of deformation also in younger sediments. At Viggiano, located along the eastern flank of the basin, recent slope deposits still attached to their source area display fault-controlled sedimentation. In this area, different climate-sedimentary cycles represented by coarse breccia talus alternated with palaeosoils are involved in the recent deformation. At Pergola, located a few kilometres northwest of the Agri high valley, the most recent fan deposits found at the foot of a major slope, including evenly bedded breccia and intercalated palaeosoils, are strongly faulted and tilted. In order to establish precise chronological constraints, palaeosoils have been sampled in several sites and at different stratigraphic levels. Radiocarbon dating supports the field evidence of very recent deformation associated to relevant displacements, yielding ages between 40 and 20 ka.

Quaternary tectonics of the Pollino Ridge, Calabria-Lucania boundary, southern Italy

Abstract The Pollino Ridge is a N120° trending morpho-structure, formed by Meso-Cenozoic carbonate rocks, that marks the boundary between Calabria and Lucania (southern Italy). It is bordered by Quaternary basins filled by both marine and continental sediments. A detailed geological survey and structural analysis in an area elongated perpendicular to the axis of the chain, ranging from the Morano Calabro basin to Mount Madonna del Pollino, was carried out. Data show that the entire mountain ridge and nearby Quaternary basins experienced several deformations in recent times, after the Mio-Pliocene thrust tectonics. Moreover, data are also consistent with numerous observations along the Calabria-Lucania boundary, from the Lauria Mountains to the Castrovillari basin. The present structure derives from reorganization of the pre-existing tectonogenetic configuration by Plio-Quaternary brittle tectonics. Mapping and kinematic analysis of a thrust along the northern (Lucanian) side of the Pollino Chain was performed for the first time. This thrust brings both the Cretaceous platform limestones and the Cerchiara Formation (lower Miocene age) over the Bifurto Formation (middle Miocene age). Low-angle transtensional faults along the southern (Calabrian) side were also mapped and analysed. These faults have created ‘younger-on-older’ type tectonic contacts. The present structure of the ridge is due to the effects of two different Quaternary tectonic stages. The first, lower Pleistocene in age, was characterized by strike-slip tectonics. It truncated ramp folds, producing new contractional and extensional features on the opposite sides of the carbonate ridge. The second stage occurred during middle Pleistocene times and was a purely extensional regime with a counter-Apenninic tensional axis, which reactivated the pre-existing structural pattern with different kinematics. However, both tectonic stages should be interpreted as a consequence of the continuous reorganization of the local stress fields as a result of a rotational field acting along the Pollino shear zone. The best explanation of this phenomenon seems to be a counter-clockwise block rotation of the carbonate ridge in an unchanging regional stress field.

Quaternary uplift vs tectonic loading: a case study from the Lucanian Apennine, southern Italy

Abstract Uplift rates have been calculated for a large sector of the Lucanian Apennine (“axial zone” of the southern Apennines, Italy), using both geomorphological observations (elevation values, ages and arrangement of depositional and erosional landsurfaces and other morpho-tectonic indicators) and stratigraphical and structural data (sea-level-related facies, fault kinematics and offset estimations). These data have been compared with those derived from clay mineralogy of Mesozoic pelagic successions (Lagonegro units), outcropping in the same sector of the chain, which gave information on tectonic loading. The values of the Quaternary uplift rates of the southern Apennines axial zone vary from a minimum of 0.2 mm / yr to a maximum of about 1.2 mm / yr . Intermediate values (0.5– 0.7 mm / yr ) have been calculated for the other studied areas. Using geomorphological features and late Pliocene to Pleistocene successions involved in the genesis of erosional and depositional landsurfaces, the same rates ( ∼0.6 mm / yr ) have been obtained for a large time span (about 2 Ma ) in the Melandro basin and adjacent Maddalena Mts. Therefore, during the last 2 Ma , the total uplift amount of the axial zone of the Lucanian Apennine is about 1.2– 1.3 km , with local peaks of 1.5 km . On the other hand, the Mesozoic pelagic units experienced a tectonic loading of 4– 5 km , as estimated by means of illite crystallinity (in the range 0.6– 1.1 Δ°2θ ), percentage of illitic layers in illite/smectite mixed layers (60–90%) and white mica polytypes (in the range of 10–35%). The Quaternary uplift and the related erosion rates of the southern Apennines are unquestionably due to strike-slip faulting and, above all, due to extensional tectonics coupled with thermal/isostatic regional raising. The gap of several kilometres derived from the comparison between uplift rates and tectonic loading values may be explained only by different exhumation modalities starting from late Miocene time.

Long- to short-term denudation rates in the southern Apennines: geomorphological markers and chronological constraints

Long- to short-term denudation rates in the southern Apennines: geomorphological markers and chronological constraints Age constraints of geomorphological markers and consequent estimates of long- to short-term denudation rates from southern Italy are given here. Geomorphic analysis of the valley of the Tanagro River combined with apatite fission track data and radiometric dating provided useful information on the ages and evolution of some significant morphotectonic markers such as regional planated landscapes, erosional land surfaces and fluvial terraces. Reconstruction of paleotopography and estimation of the eroded volumes were perfomed starting from the plano-altimetric distribution of several orders of erosional land surfaces surveyed in the study area. Additional data about denudation rates related to the recent and/or active geomorphological system have been obtained by estimating the amount of suspended sediment yield at the outlet of some catchments using empirical relationships based on the hierarchical arrangement of the drainage network. Denudation rates obtained through these methods have been compared with the sedimentation rates calculated for two adjacent basins (the Pantano di San Gregorio and the Vallo di Diano), on the basis of published tephrochronological constraints. These rates have also been compared with those calculated for the historical sediment accumulation in a small catchment located to the north of the study area, with long-term exhumation data from thermochronometry, and with uplift rates from the study area. Long- and short-term denudation rates are included between 0.1 and 0.2 mm/yr, in good agreement with regional data and long-term sedimentation rates from the Vallo di Diano and the Pantano di San Gregorio Magno basins. On the other hand, higher values of exhumation rates from thermochronometry suggest the existence of past erosional processes faster than the recent and present-day exogenic dismantling. Finally, the comparison between uplift and denudation rates indicates that the fluvial erosion did not match the tectonic uplift during the Quaternary in this sector of the chain. The axial zone of the southern Apennines should therefore be regarded as a landscape in conditions of geomorphological disequilibrium.

Landslide inventory map of the upper Sinni River valley, Southern Italy †

In this paper, we present a geomorphological landslide inventory map for an intermountain catchment in the southern Italian Apennines. The study area is seismically active, and it is characterized by high uplift rates produced by Quaternary tectonics. A total of 531 landslides of different types, relative age, and sizes, including some kilometer-scale relict landslides were mapped through the visual interpretation of 1:33,000-scale stereoscopic aerial photographs, and dedicated field surveys. Analysis of the inventory map revealed that recent landslides consist chiefly of reactivations of older landslides, and of the new landslides formed in pre-existing landslide deposits, triggered primarily by intense rainfall events, or prolonged rainfall periods. We expect that the inventory will be used for the evaluation of landslide susceptibility and hazard in the area, and to investigate the long-term geomorphological evolution of a portion of the southern Apennines.

Morphotectonic evolution of connected intermontane basins from the southern Apennines, Italy: the legacy of the pre-existing structurally controlled landscape

The opening kinematics of several Pliocene to Quaternary tectonically controlled continental basins scattered along the axis of the southern Italian Apennines and their morphological features and evolution have been compared to define the behaviour of this particular interconnected negative morphostructure. In particular, three different but morphologically connected intermontane basins have been here investigated from a morphotectonic point of view (from the north: Auletta, Vallo di Diano, and Sanza basins). They are filled by more or less thick marine and/or continental sequences of sediments, Pliocene to Quaternary in age. Such basins are shaped by erosional land surfaces and fluvial dissection. The ages of the morphological de-activation of the terraced surfaces have been roughly defined on the basis of their morpho-stratigraphic relationships with Pliocene and Quaternary deposits, and better constrained by radiometric dating. The NNW–SSE-trending fault of the Alburni Mts, bordering the Auletta basin, indicates former left-lateral transtensional kinematics and later dip-slip kinematics, whereas the N140–150°-striking master fault bounding the Vallo di Diano basin is a normal fault. The Sanza basin can be assimilated to a morphostructural trough coinciding with a long-term transfer zone of the chain, in which a severe change in stress field, uplift rate, climate conditions, and relief production occurred during Pleistocene times. Such a complicated morphostructural setting may be interpreted as a function of the original orientation of the structural depressions, only partially coeval. In this sense, the Vallo di Diano basin should represent the structural low generated by pure extension during the Pleistocene, but probably already living as a Pliocene seaway, whereas both the Auletta and Sanza basins stand for two lateral branches with oblique kinematics, inherited from a pre-existing (i.e. Pliocene in age) set.

Landslide Susceptibility Mapping Using Artificial Neural Network in the Urban Area of Senise and San Costantino Albanese (Basilicata, Southern Italy)

Landslides are significant natural hazards in many areas of the world. Mapping the areas that are susceptible to landslides is essential for a wise territorial approach and should become a standard tool to support land-use management. A landslide susceptibility map indicates landslide-prone areas by considering the predisposing factors of slope failures in the past. In the presented work, we evaluate the landslide susceptibility of the urban area of Senise and San Costantino Albanese towns (Basilicata, southern Italy) using an Artificial Neural Network (ANN). In order, this method has required the definition of appropriate thematic layers, which parameterize the area under study. To evaluate and validate landslide susceptibility, the landslides have been randomly divided into two groups, each representing the 50% of the total area subject to instability. The results of this research show that most of the investigated area is characterized by a high landslide hazard.

Long-term geomorphological evolution of the axial zone of the Campania-Lucania Apennine, southern Italy: a review

Abstract Uplift and erosion rates have been calculated for a large sector of the Campania-Lucania Apennine and Calabrian arc, Italy, using both geomorphological observations (elevations, ages and arrangement of depositional and erosional land surfaces and other morphotectonic markers) and stratigraphical and structural data (sea-level related facies, base levels, fault kinematics, and fault offset estimations). The values of the Quaternary uplift rates of the southern Apennines vary from 0.2 mm/yr to about 1.2–1.3 mm/yr. The erosion rates from key-areas of the southern Apennines, obtained from both quantitative geomorphic analysis and missing volumes calculations, has been estimated at 0.2 mm/yr since the Middle Pleistocene. Since the Late Pleistocene erosion and uplift rates match well, the axial-zone landscape could have reached a flux steady state during that time, although it is more probable that the entire study area may be a transient landscape. Tectonic denudation phenomena — leading to the exhumation of the Mesozoic core of the chain — followed by an impressive regional planation started in the Late Pliocene have to be taken into account for a coherent explanation of the morphological evolution of southern Italy.

Age constraints and denudation rate of a multistage fault line scarp: an example from Southern Italy

The morphological evolution of a carbonate fault line scarp from southern Italy, generated by transpressional faulting and evolved by slope replacement, has been reconstructed. 14C dating of faulted slope deposits (ages included between 18 ka and ∼8 ka BP) have been performed to constrain the Late Pleistocene — Holocene evolution of that scarp. Long-to short-term denudation rates have been also evaluated for the understanding of the mountain front origin. The slope shows well-defined triangular facets combined with the presence of N-S-striking mountainward-dipping fault planes. The envelope of the slope foot appears slightly curved in a planimetric view and shows an E-W-trending offset in its southern part, making such a feature quite different from the recurrent rectilinear fault scarps, often related to normal faulting. Morphostructural analysis showed that: i) the oldest displacement was generated by a fault with a reverse component of movement; ii) the slope represents an inherited feature, only recently exhumed, and developed starting from a high-angle curved surface; iii) the upper Pleistocene — Holocene extensional faulting has only affected the slope foot and associated waste deposits, causing a series of collateral morphological effects, as fluvial cut of preexisting valleys and the genesis of conspicuous mass movements.

Pliocene to Quaternary evolution of the Ofanto Basin in southern Italy: an approach based on the unconformity-bounded stratigraphic units

The Ofanto Basin is an actively evolving intra-chain basin of the Southern Apennines, Italy. It has an elongated shape, about 7 km large and 45 km long, and is E-W striking, representing a marked bend in the NW-SE regular orientation of the south-Apennines morphostructures.The basin is filled up by Pliocene to Quaternary clay, sandstone, and conglomerate, deposited in both marine and continental environments. The main sedimentary deposits are grouped into six units bounded by stratigraphic discontinuities marked by unconformities and abrupt lithological variations. Three of those discontinuities are recognisable on a regional scale and represent the physical boundaries of three supersynthems, in turn subdivided into synthems and subsynthems by basin-scale unconformities. The sedimentary evolution of the basin is herewith reported. Facies analyses and architecture of the sedimentary bodies revealed that each unit formed different alluvial and deltaic depositional systems located on the southern and northern margins of the basin. The morphology of the northern slope was probably steeper than the southern one. The oldest units were deposited in the Western sector of the Ofanto basin. Starting from the late Zanclean to the early Gelasian, the sedimentary bodies underwent an Eastward shift in their deposition, suggesting a basinward relocation of the depositional systems. Such variations in time and space seem to reflect relevant changes in accommodation space and sedimentary supply during the tectonic evolution of the basin. Eventually, correlations among adjacent basins and the meaning of the discontinuities as former erosional surfaces have been pointed out.