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Incised valleys and their fill represent important features of fluvial systems and can provide valuable information on external controls on sedimentation. Furthermore, the mode of stacking of multiple incised valleys may result in diverse connectivity of high permeability geobodies, which makes their origin and architecture important to understand for natural resources development. Based on dense borehole data and key outcrops along a 10 km-long transect, this study attempts at delineating the depositional architecture of a stacked multi-valley complex recording the Middle Pleistocene to Holocene evolution of the Tiber River system (Rome, Italy). Such a multi-valley complex is composed of four low rank/high frequency depositional sequences intercalated with pyroclastics, which fill in valley incisions entrenched into a substrate of Pliocene-Early Pleistocene marine clays. Owing to radiometric dating of pyroclastics, a robust correlation exists of valley incision and fill phases to odd and even Marine Isotopes Stages (MIS 14-1), which allows linking incised valley development to sea level changes. Located c. 20 km upstream from coeval shorelines, the investigated valleys have widths in the range of 0.5-2 Km and depth/thickness of up to 60 m and a recurrent tripartite pattern of their fills including: i) an up to 10 m thick and laterally extensive basal unit of dominantly gravelly-sandy deposits; ii) a middle unit (thickness in the range of 20-30 m) composed of vertically stacked sandy channel bodies (width in the range of 200-400 m) sided by floodplain muds; iii) a top unit composed of laterally stacked channel sands and, subordinately, floodplain muds, which result in extensive tabular sand bodies. Correlation to MIS suggests the fill of the studied incised valleys might reflect early deposition under low accommodation conditions within braided channel belts (lowstand and early transgressive phases) followed by deposition in sinuous channel belts (late transgressive and high-stand phases). In turn, successive incised valleys are stacked in an entrenching and westward shifting fashion, which is interpreted to reflect superimposition of regional uplift, topographic confinement from south-easterly sourced pyroclastics of the Albani Hills Volcanic District and glacio-eustasy. The resultant stratigraphic architecture of the Tiber multi-valley complex is such that high-permeability gravelly and sandy deposits are locally connected across successive valley fills. However, the studied example highlights how degree of connectivity of multiple incised valleys fills is ultimately controlled by external forcing factors (e.g. regional uplift and topographic confinement) superimposing to higher frequency changes of base level. It can be speculated that, by forcing lateral shifting of a fluvial stream, superimposition of differential uplift/subsidence to relative sea level changes more likely develops into less connected incised valley fills.

An integrated approach to the study of the Central Apennines thrust system has been conducted, combining together new field, geophysical, organic matter maturity and mineralogical datasets. The area comprises one of the most studied basins of the Central Apennines: the Laga basin. It developed during the Messinian time and represents the link between the internal, uplifted, Lower Miocene fold-and-thrust belt to the west, and the external, more recent part of the chain, buried below a thick pile of synorogenic, Plio-Pleistocene clastic deposits of the Periadriatic basin to the east. The Laga basin is filled by several turbiditic sedimentary sequences, largely studied in the past and mostly included into the Laga Formation, classically considered the fill of a deep marine foredeep basin connected to the flexure of the subducted Adriatic lithosphere under the Apennines. Our results clearly suggest that during Messinian, the main factor controlling depositional system architectures was thrusts activity, which governed the localization of the main depocenter in the basin and its eastward space-time migration. The occurrence of thrust activity during deposition of most of the Laga basin sedimentary succession suggests that it can be described as an internally deformed but not migrating sedimentary wedge, having features recording the transition from foredeep to wedge top depozone.

It is widely accepted that deposition in lower reaches of river systems are primarily controlled by changes in relative sea level. Responses of fluvial systems to fluctuating s.l. are complex in terms of stratigraphic and depositional architectures, with resultant peculiar stacking patterns of facies and geometries of component elements, such as channel bodies and complexes, bars, and floodplain deposits. Changes in fluvial styles and facies are mainly studied in the frame of hydrocarbon exploration and aquifer characterization. Less studied are the relations between fluvial architecture and geotechnical setting of the subsoil for geohazards assessment. It is here presented a case study aimed at identifying and modelling highly compressible floodplain-related deposits, i.e. organic mud and peat layers, in the subsoil of Rome along the Tiber River alluvial plain. A large dataset of more than 2000 boreholes allows this fluvial system to be reconstructed in 3D, and to be directly correlated with laterally contiguous deltaic deposits, where lowstand, transgressive, and highstand systems tracts and related flooding surfaces are recognised. The lower reach of the Tiber system corresponds to a strongly laterally confined, upper Pleistocene-Holocene valley infill, up to 40 km long, 2 km wide, and 70 m deep, the base of which was carved in the substratum after the last glacio-eustatic sea level fall and lowstand (between 116 and 18 ka). The valley infill was developed in response to the postglacial sea level's rise and highstand (from 18 ka to Present). The fill is composed of three distinct lithofacies assemblages: 1) basal gravels and sands, up to 15 m thick, resting on the basal unconformity and interpreted as braided river sediments deposited in the early stage of TST; 2) silty sands and sands, that are arranged in vertically stacked channel-levee complexes (up to 200 m wide and up to 10 m thick), which increasingly widen in the intermediate-upper portion of the infill; 3) encasing floodplain muddy deposits, up to 40 m thick, and commonly rich in organic matter and peat. The assemblage 1 and 2, in particular, are referred to a meandering fluvial system and are correlated to TST and HST. Compressible organic mud and peat layers represents ancient palustrine environments and are concentrated in peculiar settings within the floodplain: 1) at the transition between fluvial and deltaic systems, in the TST; 2) close to the confluence of small tributaries with the main trunk, at the concave bank of the meanders, both in the TST and HST. In the first case the marshy deposits border the inner edge of a transgressive lagoon. In the second case organic rich deposits are interpreted to develop because of damming of tributaries from rapidly aggrading levees of the main river. In the city of Rome high levels of geohazard related to subsidence and differential settlements are located right at the confluences between tributaries and Tiber River, and are therefore referable to compaction of compressible deposits. These areas are highly urbanized and tributary streams are often channelled in sewer pipes and no longer observable. Unfortunately, the presence of the buried valleys is still testified by the differential settlements that affect buildings. An attempt to define a settlement susceptibility index was carried out based on the detailed stratigraphic-sedimentological reconstructions and on the large geotechnical dataset available for the alluvial deposits. Preliminary results are encouraging since they are in good agreement with field observations and deformation velocity maps from SAR interferometry

The possibility of inferring paleoflow conditions of the Messinian turbidites from the Laga Formation (Central Apennines, Italy) is here analyzed by solving an inverse problem. This inverse problem is solved for elucidating the condition for flow ignition for current velocity, height, and sediment concentration by comparing field data with an analytical solution for the change in bed elevation, related to net-depositional turbidity currents. The obtained layer-averaged values are 2-5 m/s for current velocities, 40-100 m for current thicknesses, and 0.1-2% for sediment volume concentrations. Moreover, the duration time of these flows has been also estimated. Results show values from 1 to 15 hours, depending on the energy of the turbidity currents. This variability in the hydrodynamic conditions also provides some insight into the high-order cyclicity observed into the Laga turbidite deposits. A brief discussion on the vertical structure of a net depositional turbidity current is finally presented. The hydrodynamic conditions of a three-layer turbidity current are inferred from classical tank experiments. The behavior of each layer during the net-depositional phase of a realistic turbidity current is consequently described by using layer-averaged results of the inverse problem, as a function of the Richardson number and the Reynolds number. Results confirm subcritical turbulent behavior of the thin basal layer, a middle layer with a reduced turbulence, and an upper layer with a turbulent cloud where the mean kinetic energy is smaller than the turbulent kinetic energy.

In the centrai Apennines, interacting siliciclastic and carbonate marine clastic wedges filled the foreland basin system during the late Miocene. Conjunction of collisional thrust tectonics and prethrusting norma) faults generated a complex foredeep with intrabasinal structural highs that represented additional source areas to the basin. Detrital modes of the late Miocene centrai Apennines orogenic system range in composition from intrabasinal carbonate to quartzofeldspatholithic and calclithite arenites. The external zone of the foredeep is characterized by hemipelagic deposits, called the Orbulina Mari. Their arenite beds are composed by intrabasinal carbonate, with dominant bioclasts and minor intraclasts, and glauconite derived from an active shallow-marine carbonate source. These hemipelagic deposits are partly coeval with an d partly overlain by siliciclastic turbidites of the Frosinone an d the ArgillosoArenacea Formations, and they represent deposition within local foredeep depocenters. Siliciclastic turbidite sandstones are quartzofeldspatholithic, which documents provenances from metamorphic, plutonic, ophiolitic, and sedimentary rocks. Carbonate intrabasinal structural highs were the main source for carbonate breccias, intrabasinal arenites, and calclithites ofthe Brecce della Renga Formation, the deposits of which are locally interbedded with the coeval siliciclastic turbidite sandstones. Evolution of late Miocene sandstone detrital modes reflected the changing nature of the centrai Apennines thrust belt through time an d the complex architecture of the foreland basin system; it records the history of accretion, deformation of the foredeep, and progressive areai reduction of carbonate-producing areas along with the sedimentary an d structural evolution of local intrabasinal highs.

This work investigates the physical stratigraphy and the sedimentological characters of the Messinian turbidites of the Laga Formation, central Apennines. In particular, the study concerns the lower Messinian portion of the Laga siliciclastic turbidites cropping out between the Mts. Sibillini and the Montagna dei Fiori-Montagnone anticline. The turbidite succession of the Laga basin was subdivided into three main allounits, Laga 1, Laga 2, and Laga 3, bounded by three unconformities and their correlative conformity surfaces, named I1, I2, and I3. Each of the three units show a fining and thinning-upward trend and they are stacked to form a succession with a clear forestepping pattern, reflecting the eastward migration of the basin depocentre induced by the Apennine thrust propagation. The sequence-stratigraphic interpretation of these deposits has allowed the three units to be framed in terms of 3rd- and 4th-order depositional sequences. Two 3rd-order sequences, namely Laga Depositional Sequence (LDS; uppermost upper Tortonian-lowerMessinian) and Cellino Depositional Sequence (CDS; upper Messinian- lower Pliocene), were recognized. The evolution of both the sequences was controlled by tectonic activity and climatic changes, and records an increased thrust activity followed by a slowdown of thrust motion and by a subsequent re-acceleration of the process. This work describes, in particular, the depositional and stratigraphic features of the LDS, which constitutes a thick turbidite complex where the main architectural elements of a fan can be recognized: from slope to basin floor passing through a channelized sector. Two main processes were considered as responsible for the generation of the turbidite flows: fluvial floods and submarine failures of variable volume. Both these processes were closely related to development of shelf margin deltas migrating basinward and landward, in connection to relative sea-level fluctuations forced by a variable combination of tectonics and climate changes.

The biochronological setting proposed for the Plio-Pleistocene large mammal faunas of the Italian peninsula is based on the definition of faunal units (FUs) and mammal ages (MAs). Many evidences suggest that a multidisciplinary approach could enable us to better understand the actual meaning of a given faunal assemblage taking into account sedimentological and physical stratigraphic studies of the sedimentary successions in which local mammal faunas occur. The Pleistocene deposits of the Roman Basin can be considered a significant model to test this integrated approach. The detailed study of this sedimentary succession, in terms of facies analysis and sequence stratigraphy, sets some physical and temporal constrains to the occurrence of faunal complexes because the allocyclic control (climate and eustatic variations) on both landscape and stratigraphical evolution can affect the association type of mammal faunas. A correlation scheme between the Roman Pleistocene sequence-stratigraphic units and the mammal biochrons has been proposed; this approach constitutes a first tentative to connect the mammal fauna remains to the sedimentary processes which are responsible of their transport, stock and potential preservation in the depositional environments and to collocate this fauna in the systems tracts of the fourth-order depositional sequences recognised in the local Roman Basin Pleistocene succession., Rivista italiana di Paleontologia e Stratigrafia, Vol 110, No 2

The Ficoncella site in northern Latium (Italy) represents a unique opportunity to investigate the modalities of a short occupation in an alluvial setting during the Lower Palaeolithic. The small excavation area yielded a lithic assemblage, a carcass of Palaeoloxodon antiquus, and some other faunal remains. The main objectives of the study are to better characterize the depositional context where the Palaeoloxodonand the lithic assemblage occur, and to evaluate with greater precision the occupation dynamics. A 25 m-long well was drilled just above the top of the terrace of the Ficoncella site and faunal and lithic remains were analyzed with current and innovative techniques. The archaeological site contains floodplain deposits as it is located next to a small incised valley that feeds into a larger valley of the Mignone River. A tephra layer capping the site is 40Ar/39Ar dated to 441±8 ka. Collectively, the geochronologic, tephrochronologic and geologic data, suggest the site was occupied during MIS 13. The new results should prompt further research at Ficoncella in order to improve our understanding of the dynamics of human settlement in Europe during the Early to Middle Pleistocene.

We use Unconformity Bounded Stratigraphie Units (UBSU) to reconstruct the chronostratigraphy of volcaniclastic deposits of Roccamonfina Volcano (southern Italy). Significant discontinuities of different hierarchical order in the stratigraphic succession of the volcano have allowed us to identify the UBSU supersynthems, synthems and subsynthems. The hierarchical order has been determined by the importance and duration of the discontinuities bounding such units and by their geographic distribution. Supersynthems are bounded by regional-scale unconformities that may correspond to important tectonic events, changes in the style of eruptive activity or volcano-tectonic collapses. Synthems are bounded by unconformities marked by paleosols that are representative of considerable hiatus and extended all over the synthem. They are composed of complex sequences of depositional units. At Roccamonfina the synthems reveal cyclical eruptive activity. Unconformities bounding the subsynthems have been recognized through a detailed facies analysis. More than 100 stratigraphic sections have been analyzed and correlated, restoring them to single successive datum planes. It has been possible to reconstruct the original stratigraphic relationships, the geometry of the units, and the effects of syn-eruptive tectonic activity. This procedure revealed that the unconformity surfaces bounding depositional units show different physical expression in the proximal, medial and distal areas: (a) erosive surfaces may become amalgamation surfaces; (b) amalgamation of several depositional units can locally produce a single lithostratigraphic unit. In this case the unconformity surfaces bounding the units can be identified by the presence of discontinuous pumice and lithic concentration zones; (c) non-depositional surfaces in proximal areas (bypassing surfaces) or in interfluve areas may correspond to downslope deposits; (d) unconformity surfaces can bound different lithostratigraphic units that are the result of down-current facies variation. The pyroclastic units at Roccamonfina are organized as forestepping-backstepping sequences. We interpret this organization as resulting from waxing-waning processes associated with eruption and emplacement. In fact, the internal geometry of each synthem indicates a forestepping phase until the maximum eruption rate is achieved; as it later declines deposition occurs upslope (backstepping). This mechanism is also reproduced at smaller scale within each subsynthem. The forestepping-backstepping organization of the deposits provides an explanation for the variability of physical, chemical and sedimentological parameters observed in the Roccamonfina volcaniclastic deposits.