Salvatore Ivo Giano

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 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.

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.

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.

Chronological constraints on a Holocene landslide in an intermontane basin of the southern Apennines, Italy: Morphological evolution and palaeoclimate implications

In this work a detailed geomorphological study aimed to reconstruct the Holocene evolution of a slope largely affected by landsliding is presented. The study area is located in the lower valley of the Tanagro River, flowing in the Auletta basin, a Pliocene to Quaternary tectonic depression located along the elongation axis of southern Apennines. In order to investigate the relationships between landscape evolution and triggering factors, and to better constrain the Holocene palaeoclimate scenario in which the mass movements occurred, geomorphological data have been integrated with those deriving by the stratigraphic, chronological, and minero-geochemical analyses of the deposits genetically related to the landslide events. The investigated landslide shows a complex style of activity, with compound rotational and translational slide in the upper part of the slope evolving into flow in the lower part. The chronological evolution of the landslide activity has been constrained through radiocarbon dating of palustrine deposits, genetically related to the landslide, and of interbedded paleosols. On the basis of the presented data, the main landslide event can be placed at the beginning of the Holocene and it is followed by a period of scarse landslide activity, as demonstrated by the sedimentation of palustrine deposits within an endorheic pond. As the small basin was created by a counterslope rotation related to the main landslide phenomenon, its deposits post-date the age of the landslide. The geomorphological features related to the main gravitative event are strongly modified by reactivations occurred at the beginnings of Sub-Boreal period, which represent, in southern Europe, the warmest and wettest stage of the Holocene. As confirmed by mineralogical and geochemical data, intense and/or prolonged precipitation might have played a major role as triggering factor in reactivating the slope movement.

Morphometric analysis of fluvial network and age constraints of terraced surfaces of the Ofanto basin, Southern Italy

The Ofanto basin is an intermontane depression located in an intermediate position between the axial zone and the thrust front of the southern Apennines, Italy, filled by Pliocene to Quaternary sediments of both marine and continental origin. This basin presents some peculiarities such as the orientation of the elongation axis with regard to the strike of the chain, marked anomalies of the drainage network, and the asymmetric distribution of the terraced surfaces. Our paper focuses on the morphotectonic evolution of such a complex intermontane basin and tries to explain all those characteristics. The results obtained from both quantitative and morphostructural analyses allowed us to reconstruct the Quaternary evolution of the basin, particularly referred to the ancient land surfaces and the younger fluvial terraces. The hypothesis of a long-term process driven by the differential tectonic behaviour of the two basin flanks instead of a pure litho-structural control responsible for the fluvial network asymmetry of the Ofanto River catchment is here presented and discussed.

Deep-Seated Gravitational Slope Deformation in Urban Areas Matching Field and in-SAR Interferometry Surveys: The Case Study of the Episcopia Village, Southern Italy

A limited sector of the left side Sinni River, including Episcopia village, has been investigated matching geological and geomorphological data to In-SAR Interferometry analysis. A large Deep-Seated Gravitational Slopes (DSGSD), affecting the Episcopia slope, has been documented for the first time. The DSGSD largely develops within phyllites belonging to the Liguride Units and, in the upper portion of the slope, within the sandy and conglomerate deposits of the Sant’Arcangelo Basin. Field survey has shown typical DSGSD features as well as trenches at the top and an evident bulge at the base corresponding to the Sinni River. These data allow us to hypothesize a listric geometry of the DSGSD plane reaching a depth of about 700 m.