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

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

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

AbstractThis 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.</jats:p

Long-term morphotectonic evolution of the Molise foothills (southern Apennines)

In this study, we outline the tectonic and surface processes that have governed the landscape evolution of the outer Apenninic wedge and foreland basin in the Molise area during the late stages of the Apennines formation (Amorosi et al., 2009; Bracone et al., 2012; Amato et al., 2017), with a focus on the Trigno, the Saccione, the Biferno, the Sinarca and the Fortore River valleys. The work has been based on the combination of field data with morphometrical analysis of both the topography and the river drainage systems, resulting from the investigation of a 90m resolution DTM in a GIS environment. This approach has been widely used in literature and represents a useful tool to the landscape evolution reconstruction (Scotti et al., 2013; Buscher et al., 2017). In particular, the morphometrical investigation has been based on the elaboration of some swath profiles running parallel to the coastline and on the determination of the: 1- basin asymmetry (AF); 2- the hypsometrical integral (HI); 3- the river long profile and the derived concavity () and normalized steepness (Ksn) indexes of the main trunks and their tributaries. The results point to a north-westward increase of the medium elevation (e.g. from the Fortore to the Trigno valley, Fig. 1), which is independent from the lithological features of the study area. Also the normalized steepness index enhances an increasing trend towards the north-west (Fig. 2a). River long profile enhance a slight concave up shape for the Fortore river and a rectilinear shape for both the Biferno and the Trigno rivers (Fig. 2b). The hypsometrical integral analysis shows a north-westward increase in the HI value, suggesting a decrease in the maturity of the drainage basins from SE (e.g., from the Fortore River) to NW (e.g., to the Trigno River) (Fig. 2c and 2d). In addition, a slight asymmetry of all of the drainage basins has been recognized, with AF values generally lower than 50 suggesting valley shifting towards the hydrographic right flank (Fig. 2d). This data is also consistent with the river terraces distribution, which form a river terrace step on the hydrographic left flank of most valleys and that are less preserved on the opposite sides. The combination of field, morphostructural and morphometrical data with available stratigraphic constraints has allowed a better reconstruction of the growth and evolution of the outer Apenninic wedge in the Molise segment of the Apennines belt. In fact, it has strongly helped unravelling the features and style of the Apennines outer wedge - foredeep system recent (Late Quaternary) uplift. The picture resulting from the geomorphological data set discussed above points to differential uplift along the strike of the Apennines mountain front, with a general increasing trend of uplift towards the NW

A late Quaternary multiple paleovalley system from the Adriatic coastal plain (Biferno River, Southern Italy)

A buried paleovalley system, up to 2. km wide and exceeding 50. m in relief, made up of multiple cross-cutting depressions incised into the Lower Pleistocene bedrock, is reported from the central Adriatic coastal plain at the mouth of Biferno River. Through a multi-proxy approach that included geomorphological, stratigraphic, sedimentological and paleontological (benthic foraminifers, ostracods and molluscs) investigations, the facies architecture of distinct, superposed valley fills is reconstructed and their relative chronology established along a transverse profile with extremely high data density (average borehole spacing 75. m). Regional tectonic uplift appears as the major controlling factor of initial (Middle Pleistocene) river down-cutting and paleovalley formation. In contrast, glacio-eustatic fluctuations drove fluvial-system response over the last 120. ky, when valley incision was primarily induced by the last glacial base-level lowering and climatic forcing. A fragmented record of coastal and shallow-marine deposits is available for the lower paleovalley fill, which is penetrated by a limited borehole dataset. Multiple erosion phases probably related to the post-MIS 5e sea-level fall are reconstructed from the upper paleovalley fill, where a buried fluvial terrace succession is identified a few tens of meters below the ground surface. The flat surfaces of two buried fluvial terraces suggest longer-term, stepped relative sea-level fall, and are correlated with fluvial incisions that took place possibly at the MIS 5/4 transition and at the MIS 3/2 transition, respectively. A laterally extensive gravel body developed on the valley floor during the Last Glacial Maximum. During the ensuing latest Pleistocene-early Holocene sea-level rise the Biferno paleovalley was transformed into an estuary. Upstream from the maximum shoreline ingression, the vertical succession of well-drained floodplain, poorly-drained floodplain, and swamp deposits evidences increasing marine influence in the estuary, in response to continuing sea-level rise. The interfluves were drowned around 8. cal.ky BP, when brackish conditions developed in the study area. Decreasing marine influence in the uppermost 15. m of the paleovalley fill suggests the onset of the modern delta: when the rate of sea-level rise was overwhelmed by sediment supply, delta progradation took place

Late Quaternary palaeoenvironmental evolution of the central Adriatic coast in the Trigno mouth area (Molise Region)

[No abstract available

First assessment of the local seismic amplification susceptibility of the Isernia Province (Molise Region, Southern Italy) by the integration of geological and geomorphological studies related to the first level seismic microzonation project

This paper presents the results of the geological and geomorphological investigation carried out during the first level seismic microzonation project in the Isernia Province territory. The study area falls in one of the most seismically active areas of the Apennine chain and it has been struck, in historical times, by destructive earthquakes that caused several causalities and diffuse damages to the buildings. The analysis points out the occurrence of geological features that can determine possible site amplification phenomena related to areas with extensive outcrops of thick continental deposits or to unstable areas (both covering about 48% of the investigated areas). The latter are sometimes combined with geomorphological features such as scarps, isolated peaks, and ridges that are also responsible for possible site amplification. In addition, a susceptibility to local seismic amplification index has been introduced which highlights that more than 64% of the investigated area, along with a significant percentage of buildings, fall within the highest categories of susceptibility to local seismic amplification