Massimo Cesarano

Extensional detachment faulting on the Tyrrhenian margin of the southern Apennines contractional belt (Italy)

The tectonic evolution of the Campania margin during the late Pliocene–Pleistocene is characterized by extensional deformation coeval with the opening of the Marsili oceanic basin. The initial stages of stretching are represented in the analysed area by the development of low-angle normal faults that extended the belt in the same direction as the direction of spreading recognized for the oceanic basin. Detachment faulting was accompanied by the onset of magmatic activity and by major uplifts that resulted in the accumulation of thick conglomerate successions in the half-grabens that developed in the upper plate of the extensional detachment. Deformation continued during the Mid-Pleistocene with the formation of strike-slip and normal faults trending almost parallel to the spreading direction of the Marsili basin. These faults dissected the extensional detachment and promoted counter-clockwise block rotations about vertical axes, which accommodated the ESE-directed stretching of the Marsili basin and the consequent sinistral shear imposed on the southern Apennine chain. The development of a regional detachment fault along the Tyrrhenian margin of Campania explains the complex patterns of subsidence and uplift that characterize this area during the Pleistocene and fits well within the regional geodynamic framework of the southern Tyrrhenian Sea.

New morphostratigraphic and chronological constraints for the Quaternary paleosurfaces of the Molise Apennine (southern Italy)

New morphostratigraphic and chronological constraints for the Quaternary paleosurfaces of the Molise Apennine (southern Italy) The Molise Apennines feature numerous relicts of paleosurfaces, mostly of erosional origin, which represent the remnants of gently-rolling ancient landscapes now hanging at different altitudes above the local base-levels of erosion. Their genesis can be related to prolonged periods of relative tectonic stability alternating with periods of uplift, or to the interplay between steady tectonic uplift and climatic fluctuations. Four orders of paleosurfaces were recognized: I (> 1,100 m a.s.l.), II (900-1,000 m a.s.l.), III (750-850 m a.s.l.), IV (600-720 m a.s.l.). The most ancient orders (I and II) are cut into the bedrock and are located at the top of the Matese and Montagnola di Frosolone massifs. The youngest paleosurfaces (III—IV), partially cut into Quaternary deposits, are found along the valley flanks of the main river systems and within the Boiano, Carpino, Isernia and Sessano intramontane basins. The present study deals with the dating of the Sessano Basin Paleosurface (SBP) which is related to the IV order and is cut into the basin infill. The 40Ar/39Ar age of a tephra layer (437 ± 1.9 ka), intercalated at the top of the succession, supported by archaeo-stratigraphic, palynological and paleopedological data, allowed the SBP surface to be constrained to 350-300 ka. The SBP chronological position represents an important morphostratigraphic marker: it is the first ante quem and post quem date that allows the chronological position of the other orders of paleosurfaces to be better constrained.

Geomorphological map of the central sector of the Matese Mountains (Southern Italy): an example of complex landscape evolution in a Mediterranean mountain environment

A 1:28,000 scale geomorphological map of the central sector of the Matese Mountains (Southern Italy) is presented in this paper. Geomorphological investigation by means of remote sensing, cartographic analysis and field surveys allowed the identification of the main geomorphic processes and to map the related landforms which are both of monogenetic and polygenetic origin. Most of them are erosional landforms generated by the action of periglacial, glacial and karst processes which often occur under the control of the geological structure. Glacial relics and polygenetic landforms of glaciokarst and fluviokarst origin provide good evidence of the strong influence of variable climatic conditions on landform genesis during the Quaternary. They also highlight the influence of extensive tectonics during the Quaternary which caused progressive uplift, fragmentation and disarticulation of the developing mountainous landscape and its consequent polycyclic evolution. The map illustrates the geomorphologic peculiarities of the Mediterranean mountain landscape that typically characterizes the Apennine chain, and contributes to the understanding of its tectonic evolution and the influence of climate and climatic changes on landscape evolution. It further provides a basic map for land planning policy including the exploitation of the geological heritage and the development of sustainable mountain tourism and geo-tourism.

Shear deformation of pelitic rocks in a large-scale natural fault

Abstract Experimental tests on simulated clay gouges and data from shear zones developed in pelitic media at convergent plate margins provide contrasting evidence regarding the hydraulic characteristics and, in consequence, the frictional properties of sheared clays. The natural shear zone analysed in this work indicates that shear strain can induce mineralogical changes in smectite-bearing sediments that imply loss of water from the smectite minerals and their replacement with anhydrous illite minerals. The extreme localization of the illitization process and its geometric characteristics allow us to argue that the reaction is initiated by stress concentration along the shear zone and, once discrete shears develop, it is accelerated by both cataclasis and the frictional dehydration of smectites. This process would generate fresh water from within the shear zone, leading to fluid overpressure build up, and can account for the observed hydraulic circulation and salinity anomalies in modern accretionary prisms.

The 2002 Molise, Italy, Earthquake: Geological and Geomorphological Data on the San Giuliano di Puglia Area

The small village of San Giuliano di Puglia sustained the most severe damage from the Molise earthquake sequence of 2002. This study involved detailed geological and geomorphological mapping and is supported by a large set of geotechnical, geophysical and drill-hole data available from existing studies. These data were used to compile a seismic microzonation map of the San Giuliano di Puglia area as part of a study officially commissioned by the Department of Civil Protection. The map provides seismic hazard information that will be useful in the repair and reconstruction of the town.

Long-term landscape evolution of the Molise sector of the central-southern Apennines, Italy

Abstract This paper concerns the reconstruction of the main stages of the long-term landscape evolution of the Molise portion of the central-southern Apennines along a transect divided into three sectors (SW, Central and NE). Analysis mainly focused on geomorphological, stratigraphical and structural data supported by chronological constraints, coming from an overall review of past literature and several studies carried out by the authors of the paper during the last 20 years. The results obtained allowed the elaboration of a conceptual model of the long-term evolution of the Molise sector of the central-southern Apennines. Starting from the Pliocene, the emersion of the Molise area occurred gradually from SW to NE, allowing a polycyclic landscape to evolve under the major controls first of compression then transtensional to extensional tectonics as well as climatic variations. Principal markers of the Quaternary geomorphological evolution of the Molise area are represented by the infill successions of the intermontane tectonic depressions located in its internal, SW sector and by four orders of palaeosurfaces that developed between the Early Pleistocene and the beginning of the Late Pleistocene across the region. These markers testify to the alternation of phases of substantial tectonic stability and uplift whose spatial-temporal distribution could be assessed along the investigated transect. Results highlight that the most important stages of landscape evolution occurred during the Early and Middle Pleistocene. At the beginning of the Late Pleistocene, the Molise sector of the Apennine chain had already reached its present setting and further landscape evolution occurred under the major control of climate and land-use.

INTEGRATED STRATIGRAPHY OF MIDDLE-LATE MIOCENE SYNOROGENIC DEPOSITS OF THE EASTERN SOUTHERN APENNINE CHAIN: THE SAN BARTOLOMEO FLYSCH

The present paper deals with the stratigraphic and biostratigraphic study of the middle-late Miocene thrust-top basin deposits of the San Bartolomeo Flysch, exposed north of Matese mountains and analysed during the geological survey of the sheet N° 405 Campobasso of the new Geological Map of Italy, 1:50.000 scale. The integrated study of calcareous nannofossils and planktonic foraminifera, based on the semi-quantitative distribution range of index species, revealed the presence of age-diagnostic assemblages which are comparable with those of different middle-late Miocene deep-marine sedimentary settings of the Mediterranean Basin. The biostratigraphic dataset suggests an early Serravallian – early middle Tortonian age. In terms of calcareous nannofossil biostratigraphy, the studied succession falls between the Last Occurrences of Sphenolithus heteromorphus and the First Occurrence of Discoaster bellus gr., corresponding to the MNN6 – MNN8 zone interval. In terms of planktonic foraminiferal biostratigraphy the studied sediments fall between the Last Occurrence of Globorotalia peripheroronda and the First Regular Occurrence of Neogloboquadrina acostaensis , corresponding to the MM6 p.p. - MMi10 p.p. zone interval. This study documents the applicability of the recent Mediterranean middle –late Miocene biozonations for the biostratigraphic study of siliciclastic synorogenic sediments, and challenges the most recent studies that dated the San Bartolomeo Flysch to the late Tortonian- early Messinian.

Lower plate geometry controlling the development of a thrust-top basin: The tectonosedimentary evolution of the ofanto basin (Southern Apennines)

The Ofanto basin is a Pliocene–Pleistocene thrust-top basin that formed with an unusual east–west orientation along the frontal part of the Southern Apennine Allochthon during the latest stages of tectonic transport. Its tectonic and sedimentary evolution was studied integrating field surveys, biostratigraphic analyses and the interpretation of a large seismic grid. Well data and seismic interpretation indicate that a large east–west-trending normal fault underlies the northern margin of the basin, displacing the Apulian carbonates that form the foreland and the footwall of the Southern Apennine Allochthon. In our reconstruction the Ofanto basin formed at the rear of the bulge caused by buttressing of the Southern Apennine Allochthon against this normal fault. In a second stage of contraction, the footwall of the Southern Apennine Allochthon was involved in deformation with a different trend from the normal faulting and buttressing. This caused eastward tilting of the basin and broad folding around its eastern termination. Good stratigraphic constraints permit the age of buttressing to be defined as Early Pliocene, and that of the shortening in the Apulian carbonates as Early Pleistocene. This study highlights the importance of early orogenic normal faults in conditioning the evolution of the frontal parts of orogenic wedges. Supplementary material: A 3D reconstruction of the base of the Pliocene deposits of the Ofanto basin, based on seismic interpretation, is available at www.geolsoc.org.uk/SUP18559.

Recurrent Superficial Sediment Failure and Deep Gravitational Deformation in a Pleistocene Slope Marine Succession: The Poseidonia Slide (Salerno Bay, Tyrrhenian Sea)

A large number of exposed scars, originated by multievent sediment failures, have been identified on the southern flank of a deep submarine valley in Salerno Bay (Southern Tyrrhenian Sea), between depths of 300 and 700 m. A 200 km2 complex landslide lies across a 17 km-long SW-NE trending anticline, which is exposed 40 m above the seafloor of the continental slope and folds a Pleistocene marine successions. The exposed anticline, as well as others which are more subdued, have been formed by gravity-driven deformation of a deep and unconsolidated slope succession. The deep deformation seems to be coeval with recent stages of regional tectonic activity, given that a regional unconformity related to MIS 6 lowstand seals both the deep landslide features and the fault planes. A combined dataset of 2D high resolution seismics, swath-bathymetric digital elevation model of the seafloor and a gravity core was used to establish a possible relation between recurrent sediment failures at the seabed and the stack of positive reliefs in the compressional toe region of the buried landslide system and to learn more on the timing of the deformation phases.

Geomorphic response to late Quaternary tectonics in the axial portion of the Southern Apennines (Italy): A case study from the Calore River valley: Geomorphic response to the Quaternary tectonics in the Calore R valley

The present study focuses on themorphotectonic evolution of the axial portion of the SouthernApennine chain between the lower Calore River valley and the northern Camposauro mountain front (Campania Region). A multidisciplinary approach was used, including geomorphological, field-geology, stratigraphical, morphotectonic, structural, Ar/Ar and tephrostratigraphical data. Results indicate that, from the Lower Pleistocene onwards, this sector of the chain was affected by extensional tectonics responsible for the onset of the sedimentation of Quaternary fluvial, alluvial fan and slope deposits. Fault systems are mainly composed of NW-SE, NE– SWandW-E trending strike-slip and normal faults, associated toNW-SE andNE–SWoriented extensions. Fault scarps, stratigraphical and structural data and morphotectonic indicators suggest that these faults affected the wide piedmont area of the northern Camposauro mountain front in the Lower Pleistocene–Upper Pleistocene time span. Faults affected both the oldest Quaternary slope deposits (Laiano Synthem, Lower Pleistocene) and the overlying alluvial fan system deposits constrained between the lateMiddle Pleistocene and the Holocene. The latter are geomorphologically and chrono-stratigraphically grouped into four generations, I generation: late Middle Pleistocene–early Upper Pleistocene, with tephra layers Ar/Ar dated to 158±6 and 113±7 ka; II generation: Upper Pleistocene, with tephra layers correlated with the Campanian Ignimbrite (39 ka) and with the slightly older Campi Flegrei activity (Ar/Ar age 48±7 ka); III generation: late Upper Pleistocene–Lower Holocene, with tephra layers correlated with the Neapolitan Yellow Tuff (~15ka); IV generation: Holocene in age. The evolution of the first three generations was controlled by Middle Pleistocene extensional tectonics, while Holocene fans do not show evidence of tectonic activity. Nevertheless, considering the moderate to highmagnitude historical seismicity of the study area, we cannot rule out that some of the recognized faults may still be active. Copyright