Search

_, Geomorphology for Society, Conference proceedings

The chrono-stratigraphic and palaeo-environmental characters of the Boiano and Sessano intramountain basins infilling was investigated by new deep cores data and related tephrostratigraphy, pollen data and Ar/Ar datings, integrated by detailed geomorphological analyses. The basins are filled by thick fluviallacustrine successions of Middle Pleistocene to Holocene age. In particular the Sessano basin infilling covers an interval that spans from OIS 15 to OIS 12, when it dried up and was affected by tectonics. The Boiano basin lacustrine-palustrine infilling covers an interval that spans from OIS 13 to OIS 9, when sedimentation changed to fluvial-marshy conditions. The high sedimentation rate during the Middle Pleistocene suggests that the sector of the basin including the urban area of Boiano was subsiding, due to tectonic activity.

The Boiano Basin is one of the largest Quaternary intermontane basins of the central-southern Apennines within one of the most tectonically active areas of the Mediterranean region. In order to reconstruct its entire Quaternary stratigraphic, tec- tonic, and palaeoenvironment evolution, lithofacies and palaeomagnetic analyses have been performed on a 900 m-deep borehole (CP1) drilled in the southwestern sector of the basin. The Quaternary succession consists of an alternating of alluvial fan and fluvial-marshy deposits for a total thickness of 240 m, unconformably laying on Lower Miocene deposits of the Sannio Unit, thrusted on upper Miocene deposits of the Molise Flysch. In addition, the stratigraphic study and facies distribution of 29 intermediate and shallow wells drilled in the basin, allowing us to define the thick- ness and lithofacies variations of the Quaternary sedimentary units inside the entire Boiano Basin in the sector of Campochiaro alluvial fan. Our results demonstrate that the Boiano Basin infilling started during the late Early Pleistocene (c. 1.1 Ma) and developed with variation in lithofacies distribution and thickness. The first deposi- tional unit (Early Pleistocene-early Middle Pleistocene in age) was palustrine and fluvial-marshy, the second (Middle Pleistocene in age) was characterized by the occurrence of the first cycle of alluvial fan deposition, the third (late Middle Pleisto- cene in age) was newly palustrine and fluvial marshy and, finally, the fourth recorded two cycles of alluvial fan deposition (late Middle Pleistocene and Late Pleistocene in age, respectively), interspersed by short periods of palustrinity, tephra layers deposi- tion, and palaeosols development. The study allows the hypothesizing that the Qua- ternary infilling was accommodated within a graben (or semigraben) structure, affected mainly by extensional fault systems localized in the inner part of the basin and secondly by fault systems bounding the basin.

During the Late Pleistocene and Holocene periods, the Italian coasts have undergone a very articulated geological and geomorphological evolution, due to the complex and differentiated interaction of endogenous and exogenous dynamics. Aim of this study is to implement a geodatabase concerning the geomorphological, stratigraphic, biological and archaeological palaeo sea-level proxies located in the Gulf of Naples, in order to provide a catalogue of the most representative markers and an overall picture of ancient shorelines positions since the Late Pleistocene

This study was conducted within the framework of the “Coastal Morphodynamics” Working Group (WG) of the Italian Association of physical Geography and Geomorphology (AIGeo), according to the Institute for the Protection and Environmental Research (ISPRA) for the updating of the legend for the “Geomorphological Map of Italy”. The WG deals with the legend for the coastal areas, focusingits work on marine, lagoon and aeolian landforms, processes and deposits. In particular, the legend aims to classify coastal landforms in order to contribute to hazard and risk assessment,for supportingland-use planning and management. The legend allows the mapping of each landform in function of its genesis as well as its evolution and present dynamics, providing information about morphological characteristics at small and large scales. The relict morphological features and the active ones are reported along with the quantitative parameters useful for the description of the present wave/climate conditions and morphodynamics. As a result of the activities and experiments carried out by the “Coastal Morphodynamics” AIGeo WG during the last years, some examples of coastal geomorphological mappings at different scales (1:5,000 and 1:25,000) have been developed and are presented in this paper. The maps focus both on littoral plains and rocky coast dynamics as well as on the interactions with anthropic modifications.

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.