1,721,005 research outputs found
I ciottoli dei conglomerati medio-pliocenici dell'Appennino campano: provenienza, elaborazione, ambiente di deposizione.
No full textI conteggi per stabilire la composizione delle popolazioni di ciottoli sono stati effettuati utilizzando metodologie statistiche. I litotipi dominanti sono arenarie e calcari, seguono marne, selci, quarziti e siltiti; i clasti granitici sono occasionali. I ciottoli provengono pressochè esclusivamente dai terreni dell'U. Sannitica e dalle unità terrigene fliscioidi mioceniche s.l. Le Unità Carbonatiche di Piattaforma (mesozoiche) non costituivano un rilevante alto morfologico, e pertanto non contribuivano all'alimentazione clastica del bacino
Orogenic evolution of the northern Calabria–southern Apennines system in the framework of the Alpine chains in the central-western Mediterranean area
Full text linkThe northern Calabrian ranges and the southern Apennines are part of a single orogenic segment of the Alpine chain system framing the central-western Mediterranean Sea. Three main tectonic complexes characterize this orogenic chain: (1) remnants of the overriding plate, including Variscan Paleozoic basement (Calabria-Peloritani terrane), which tectonically cover (2) an Alpine metamorphic belt, corresponding to an exhumed subduction channel, formed by slices of the Calabria-Peloritani terrane, meta-ophiolites (metamorphic Ligurian Units), and some successions of the continental Adria plate (downgoing plate), which are in turn superposed onto (3) a fold-and thrust belt composed of remnants of an oceanic accretionary prism (nonmetamorphic Ligurian Units) on the top and an underlying imbricate orogenic pile consisting of shallow-water to pelagic continental Adria successions, also including buried shallow water carbonates of the Apulian Platform. The exposed Apulian Platform domain (Puglia region) and the Adriatic Sea represent the current foreland. The orogenic chain results from the subduction of Ligurian Ocean lithosphere beneath the European plate/Calabria-Peloritani terrane starting during the Paleocene–Eocene. The restored mean tectonic vergences indicate that the thrust front migrated to the south in the Eocene–Langhian period, turning to the east during the Serravallian–Pleistocene interval. After the complete closure of the Ligurian Ocean in the Early Miocene, the subduction continued with the involvement of the continental part of the Adria plate, triggering crustal shortening until the middle Pleistocene. Complex geometries, reflecting the articulated paleogeographic domains formed by alternating shallow-water carbonate platforms and deep basins, controlled the shape of the thrust front–foredeep–forebulge system. Thin- and thick-skinned thrusting episodes have alternated during the orogenic shortening; however, since the early Pliocene, deep seated, ramp-dominated thrust faults have driven the crustal shortening, resulting in widespread envelopment thrusting, and out of-sequence structures in the allochthonous wedge. The alternating different tectonic styles also resulted from the involvement in the subduction system of the continental Adria lithosphere, which is thicker under the carbonate platforms and thinner under the interspersed pelagic basins and the western margin facing the Ligurian Ocean. The involvement of thicker lithosphere during the subduction process caused two main backstops that triggered thick-skinned tectonics. The synorogenic sedimentation was ruled by the migration of the forebulge-foreland basin system, with flexure of the continental part of the Adria plate since the Oligocene and erosion of a large part of the Apennine and Apulian carbonates that fed the foredeep basins with calciclastic supply. Siliciclastic input, which originated from both the overriding plate and orogenic wedge, joined with orogenic volcaniclastics, marks the sedimentation in the foreland basin system, including the mature stage of the foredeep troughs and the wedge-top basins located on the top of the chain, with the latter also recording calciclastic sedimentation that originated from the erosion of the piled-up Adria carbonate successions
Evidence of brackish lagoons in the Pliocene of Irpinia (Southern Italy).
No full textThe sedimentary section outcropping in the locality S. Andrea near Montecalvo Irpino has indicated the presence of paleoenvironmental characters which are referred to as a marine basin margin evolving to the regressional phase. This succession is constituted by coastal sandy sediments which end at the top with silty-clays lagoonal sediments. The analysis of the sedimentary facies and the studied ostracod fauna allowed the definition of 4 facies assemblages (A1-A4) each of which is characteristic of different environmental conditions: upper shoreface-foreshore, coastal eolic dunes, washover fan and brackish lagoon. As far as the ostracodes are concerned, two new species are established and illustrated, Euxinocythere (Maeotocythere) nasserii n. sp. and Leptocythere lagunaris n. sp. from brackish environments
Evidence of brackish lagoons in the Pliocene of Irpinia (Southern Italy).
No full textThe sedimentary section outcropping in the locality S. Andrea near Montecalvo Irpino has indicated the presence of paleoenvironmental characters which are referred to as a marine basin margin evolving to the regressional phase. This succession is constituted by coastal sandy sediments which end at the top with silty-clays lagoonal sediments. The analysis of the sedimentary facies and the studied ostracod fauna allowed the definition of 4 facies assemblages (A1-A4) each of which is characteristic of different environmental conditions: upper shoreface-foreshore, coastal eolic dunes, washover fan and brackish lagoon. As far as the ostracodes are concerned, two new species are established and illustrated, Euxinocythere (Maeotocythere) nasserii n. sp. and Leptocythere lagunaris n. sp. from brackish environments
Geochemistry and Geometrical Features of the Upper Cretaceous Vitulano Para-Autochthonous Karst Bauxites (Campania Region, Southern Italy): Constraints on Genesis and Deposition
No full textIn the Vitulano area, Upper Cretaceous bauxite bodies fill small depressions and karst cavities within Cretaceous shallow-water limestones. These bauxites were studied to understand the processes that led to their formation. Geochemical, mineralogical, and petrographic analyses were carried out on the bauxite samples, together with image analysis providing geometric parameters. The texture of Vitulano bauxite consists of ooids and sub-circular aggregates dispersed in a predominantly Ca-rich matrix. Ooids are generally formed by a single large core, often surrounded by an alternation of different aggregates of boehmite and Al-hematite reflecting different climate periods. The composition is dominated by the major elements Al2O3 and CaO with lower concentrations of Fe2O3 and SiO2. Boehmite, calcite, hematite, and anatase are the main mineralogical phases identified. Image analysis provided values of fractal dimension D that gives information on carbonate platform exposure times since it is linked to long-lasting sub-aerial events and diffusion-limited cluster aggregation processes. The tectonic evolution of the area played an important role in the genesis of the Vitulano bauxites since it favored the erosion, transport, and re-deposition of pre-existing bauxite material from the surrounding Campania bauxites. Based on this hypothesis, Vitulano bauxites are defined and classified as para-autochthonous, and this was supported by Eu/Eu* vs. Sm/Nd and Eu/Eu* vs. TiO2 Al2O3 indices displaying a similarity between Vitulano and the other Campania bauxites
Pliocene Paralic environments of Irpinia-Daunia Basin (Baronia Mountains, Southern Apennines, Italy)
No full textThis paper describes and interprets two stratigraphic sections pertaining to the regressive part of Baronia Synthem across the regressive part of Baronia Synthem, located near the villages of Flumeri and Vallesaccarda (Ariano Irpino area, Southern Italy). Four different depositional environments have been recognized: fluvial, lagoon, foreshore and shoreface. Fluvial deposits, occurring in the Flumeri section, consist of clast-supported conglomerates, horizontal laminated sands and muddy silts with freshwater ostracod assemblages, indicating deposition in braided river low-sinuosity channels. In the Flumeri section lagoonal deposits are generally represented by structureless layers of dark clay including ostracods of brackish coastal lagoon connected with shallow-marine waters. In the Vallesaccarda section lagoonal sediments only occur as muddy clasts. Foreshore deposits are represented by well sorted yellow sands with low-angle cross lamination; a horizontal layer of stratified gravels outcrops in Vallesaccarda section. The shoreface deposits consist of poorly sorted sands with trough cross stratification formed in a bar and trough system, of symmetric ripples layers, and of abundant mollusc shell debris; in the Vallesaccarda section a tempestite interval generated by storm activity has been found. In Flumeri section littoral and lagoonal facies assemblages alternate; in Vallesaccarda section only nearshore sediments outcrop. Nearshore deposits denote a wave-dominated coastal marine environments. These data contribute to a better knowledge of the distribution of paralic facies on the Western margin of the Pliocene Irpinia-Daunia Basin
Deformation and stratigraphic evolution of the Ligurian Accretionary Complex in the southern Apennines (Italy)
No full textThis work provides a structural analysis and a stratigraphic revision of the sedimentary successions of the Ligurian Accretionary Complex (LAC) cropping out in the southern Apennines along the boundary between Campania, Lucania and Calabria regions. Two fold and thrust sets characterize the progressive deformation related to the Lower Miocene inclusion of these successions in the tectonic accretionary wedge. A third deformation stage, affecting also the Middle-Upper Miocene unconformable wedge-top basin deposits, is associated to the thrust front eastward migration. In this orogenic phase the Apennine thrust sheet pile, formed by LAC and Apennine Platform Units, tectonically covered the successions located in the westernmost sector of the Lagonegro-Molise Basin. Finally a Pliocene-Middle Pleistocene regional fold set deformed the whole orogenic prism as consequence of a thick-skinned tectonics expressed by means of deeply rooted thrusts in the buried Apulian Platform carbonates. Maghrebian Flysch Basin and LAC successions show a similar stratigraphy indicating continuity between paleogeographic basin domains, as well as between the Paleogene-Lower Miocene succession of Sicilide Unit and the corresponding deposits of Lagonegro-Molise Basin as consequence of drowning of the interposed Panormide Platform starting from the uppermost Cretaceous
Improved statistical multi-scale analysis of fractured reservoir analogues
No full textThis paper includes the results of the application of novel methodologies for the statistical analysis of tensile fracture attributes (spacing, density, and aperture). The statistical methods have been applied to a fractured Lower Cretaceous carbonate succession cropping out in the Sorrento Peninsula (Naples area, Italy), representing a geological analogue of buried reservoirs of southern Apennines major oil fields. As fracture networks (observable from outcrop to the crystal scale) can significantly affect the hydraulic behavior of a fractured reservoir, the definition of appropriate models of fracture spacing and aperture probability distribution at various scales represents an important goal of structural analysis. In order to achieve such an objective, sampling has been carried out at different scales, by means of traditional scan lines at outcrop, as well as micro-scan lines carried out both by a digital micro-camera (50×) and by the optical microscope (200×). Fracture spacing and density analysis are mainly aimed at establishing the characteristics of joint spatial distribution over a range of scales. Aperture analysis is aimed at verifying that the aperture cumulative frequency is described by a power law and, in the latter instance, to provide an effective method for a more precise determination of the exponent of the power law. Finally, new expressions are provided, in closed form, in order to calculate the confidence interval of the power-law exponent. The proposed criteria provide handy and effective methods for a significantly improved statistical analysis of fracture attributes. © 2010 Elsevier B.V
Landslide susceptibility assessment in the southern sector of the Tammaro River basin (Italy)
No full textNumerous methods have been proposed in literature for the landslide susceptibility assessment at basin scale using Geographical Information Systems (GIS). Among them, statistical methods have became increasingly popular in recent years. In particular, the Homogeneous Territorial Unit (HTU) method [DE VITA et al., 1994; GUIDA et al., 1996; CALCATERRA et al., 2010] has been applied in this work, which is well suited to problems of slope stability in structurally complex formations [ESU, 1977]. HTU method was applied to the southern sector of the Tammaro River basin, which corresponds to the municipalities of Paduli and Pietrelcina, in the southern part of the Apennines fold-and-thrust belt (Campania Region, Italy). From a geological point of view, this area consists of argillitic-marly-calcareous and argillitic-marly formations, known as "Varicoloured Clays", a structurally complex formation [ESU, 1977], well-known in literature for its susceptibility to landslides. The area of interest includes about 73 km2 of hilly territory, where 303 landslides, divided in 127 earthflows, 87 rotational/translational slides and 89 earth slides-earthflows, have been mapped, at 1:5.000 scale, by means of field survey and stored in a GIS-database. Moreover, geolithological and geomorphological maps (at 1:10.000 scale), as GIS-layers, were used to implement the homogeneous domains for the statistical analysis. Such domains represent specific mapping units, called HTUs, which define the classification of each slope-instability factor into four classes, stored into a single map, or layer. By means of the overlay of the HTU map and the landslide-inventory map, the susceptibility assessment is then extended to non-landslide areas by applying a statistical method
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