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Morphometric evidence of the topographic growth of central Apennines
No full textOn the basis of DEM analysis, we examine the tectonic geomorphology
of the Apennines in central Italy to figure out the topographic
evidence for how Apennines landscape was shaped by its emergence
above sea level, in the tectonic context of a growing mountain chain.
Geologic and geomorphic data suggest that its topographic growth was
slow during the phase of crustal shortening (Miocene-Pliocene), but accelerated
at the end of lower Pleistocene, when tectonics was already
dominated by extension. Such different uplift rates should influence the
development of the resulting landforms. We investigate the topography
and the drainage features of a E-W transect across central Italy, focusing
on topographic metrics, drainage pattern and stream long profiles.
The results indicate that the Apennines topography is characterized by
the superimposition of a short wavelength (10-30 km wide spacing),
linked to local tectonic structures (extensional on the Tyrrhenian side
and compressive on the Adriatic side), and a long one that corresponds
to a broad topographic bulge 200-300 km wide, that records a regional
uplift. As a response, the rivers incised the topography of the growing
chain mostly the same and, interacting with climate changes, generated
at least three major inset alluvial terraces. In particular, on the Tyrrhenian
side, the rectangular drainage pattern indicates the strong influence
of the extensional tectonics. This is also evident in the stream long profiles,
where knickpoints and knickzones correspond with tectonic lineaments
and extensional basins respectively. The hydrographic network
draining to the Adriatic Sea shows a parallel pattern. The knickpoints
of the stream long profiles generally correspond to rock changes and to
very deep and narrow gorges, where the rivers incised the compressive
structures reaching their cores. A high-resolution DEM of an area just
south of Ancona provided information at a nested scale of observation.
This region contains two major low relief surfaces. The one at higher elevations
is located at the crest of the chain cutting across carbonates
and marls. The other surface is inset into the flanks of the range and
mostly cuts across turbidites. A third geomorphic surface, located more
eastward, is underlain by Pliocene and Quaternary deposits. Coupling
the morphometry analysis, the map of Pliocene-lower Pleistocene deposits,
and previous studies, we explore the relationships among the landscape features, the regional vertical tectonism, and the local deformational
processes. The results are consistent with a landscape dominated
by the broad Quaternary uplift superimposed on local tectonics,
suggesting new constrains for the long term evolution of the landscape
of central Italy in the context of the Apennines topographic growth
Analisi geoambientale, cartografia geomorfologica e tecniche GIS per la gestione del territorio. Mem. Descr. Carta Geologica d’Italia
No full textComment on: “Geomorphological, paleontological and 87Sr/86Sr isotope analyses of early Pleistocene paleoshorelines to define the uplift of Central Apennines (Italy)”
No full textHolocene travertine deposition and human settlement in the limestone valleys of the Marchean Apennine (central Italy)
No full textInvestigations made in different parts of the world indicate that significative travertine deposition occurred in the early Holocene and declined in the late Holocene. Also in the calcareous sectors of the central Apennine the construction of travertine dams started in the early Holocene together with a widespread development of thermophile forests and soil
Holocene aggradation/degradation phases of tufa dams in northern Ethiopia and central Italy: a palaeoclimatic comparison between East Africa and Mediterranean Europe.
No full textThe 14C dating of buried soils and peat layers from tufa dammed swampy-lacustrine sequences allows us to outline the aggradation/degradation sequence of Holocene tufa dams in central Italy and northern Ethiopia. In northern Ethiopia, the aggradation of tufa dams started before 9,510 ± 100 14C yr BP (11,080–10,590 yr cal BP), turned to decline around 5,610 ± 70 14C yr BP (6,450–6,305 yr cal BP) with short-lived alternating stages of incision/deposition since ca. 4,710 ± 70 14C yr BP (5,580–5,320 yr cal BP). After ca. 2,380 ± 50 14Cyr BP (2,710–2,340 yr cal BP), fluvial incision completely cut the tufa dams. In central Italy, the aggradation of tufa dams started before 9,310 ± 100 14C yr BP (10,211–10,184 yr cal BP) and declined after 6,190 ± 70 14C yr BP (7,240–6,990 yr cal BP). From ca. 4,610 ± 100 14Cyr BP (5,600–5,050 yr cal BP), alternating stages of dam erosion/aggradation occurred, eventually followed by a phase of deep incision down to the present valley floors. The occurrence of similar trends of tufa dam aggradation/erosion in Mediterranean Europe and East Africa, as compared with the patterns of Holocene climate in both areas seems to indicate that cold/warm and dry/wet fluctuations have controlled the aggradation/erosion phases of tufa dams including their ultimate incision by streams. On the other hand, the comparable evolution of tufa dams in areas quite different in geographical position points out the significant morphogenetic role of climate changes at the global/supra-regional level.The 14C dating of buried soils and peat layers from tufa dammed swampy-lacustrine sequences allows us to outline the aggradation/degradation sequence of Holocene tufa dams in central Italy and northern Ethiopia. In northern Ethiopia, the aggradation of tufa dams started before 9,510 ± 100 14C yr BP (11,080–10,590 yr cal BP), turned to decline around 5,610 ± 70 14C yr BP (6,450–6,305 yr cal BP) with short-lived alternating stages of incision/deposition since ca. 4,710 ± 70 14C yr BP (5,580–5,320 yr cal BP). After ca. 2,380 ± 50 14Cyr BP (2,710–2,340 yr cal BP), fluvial incision completely cut the tufa dams. In central Italy, the aggradation of tufa dams started before 9,310 ± 100 14C yr BP (10,211–10,184 yr cal BP) and declined after 6,190 ± 70 14C yr BP (7,240–6,990 yr cal BP). From ca. 4,610 ± 100 14Cyr BP (5,600–5,050 yr cal BP), alternating stages of dam erosion/aggradation occurred, eventually followed by a phase of deep incision down to the present valley floors
Presence-only approach to assess landslide triggering-thickness susceptibility. A test for the Mili catchment (north-eastern Sicily, Italy)
No full textThis study evaluates the performances of the presence-only approach, Maximum Entropy, in assessing landslide triggering-thickness susceptibility within the Mili catchment (Sicily, Italy). This catchment underwent several meteorological stresses, resulting in hundreds of shallow rapid mass movements between 2007 and 2011. In particular, the area has become known for two disasters, which occurred in 2009 and 2010; the first weather system did not pass directly over the catchment; however, peak rainfall was registered over the basin during the second meteorological event. Field data were collected to associate the depth from the slope surface that material was mobilised at the triggering zone to each mass movement within the catchment. This information has been used to model the landslide susceptibility for two classes of processes, divided into shallow failures for maximum depths of 1 m and deep ones in case of values equal or greater than 1 m. Topographic attributes from a 2-m DEM were used as predictors, together with medium resolution vegetation indexes derived from ASTER scenes and geological, land use and tectonic maps. The presence-only approach discriminated between the two depth classes at the landslide trigger zone, producing excellent prediction skills associated with relatively low variances across a set of 50 randomly generated replicates. The role of each predictor was assessed to ascertain the significance to the final model output. This work uses simple field measurements to produce triggering-thickness susceptibility, which is a novel approach and may perform better as a proxy for landslide hazard assessments with respect to more common susceptibility practises
“Climate changes, active tectonics and related geomorphic effects in high mountain belts and plateaux”, Proceedings of the IAG International Symposium in Addis Ababa (Ethiopia)
No full textElements to correlate the marine and continental sedimentary successions lying on the Latium and Abruzzo margins of the Apennines
No full textL’Appennino centrale presenta caratteri geologici e geomorfologici che documentano l’intensa influenza della tettonica estensionale e del sollevamento regionale sulla sua evoluzione recente. In questo lavoro si intendono evidenziare gli elementi di correlazione tra le successioni marine e continentali della fascia periadriatica abruzzese e peritirrenica laziale, al fine di proporre dei vincoli temporali all’evoluzione recente dell’Appennino. Gli elementi geomorfologici più antichi, riscontrabili lungo tutta la catena appenninica, sono rappresentati da superfici gentilmente ondulate. Sul versante occidentale la tettonica distensiva legata all’apertura del Tirreno ha generato una complessa serie di bacini neoautoctoni più antichi in Toscana (dal Tortoniano) e più recenti nell’area laziale (dal Pliocene). Sul versante adriatico il sollevamento della catena ha generato discordanze angolari che individuano numerose sequenze sedimentarie in assetto monoclinalico. Sul versante tirrenico della catena, si depositano sedimenti progressivamente più grossolani riferibili alla fine della biozona a Globorotalia crassaformis. In particolare, al tetto di questi depositi, e alla base della biozona a Globorotalia inflata, è stato trovato, a Valle Ricca, un livello vulcanico datato 2.1 Myr. Su tale successione si appoggiano in discordanza le “Argille Sabbiose del Chiani-Tevere” di ambiente marino e salmastro. Similmente, sul versante adriatico, un livello vulcanico datato 2.1 Ma è stato rinvenuto all’interno di una sequenza di depositi di ambiente pelitico presso Bellante. Questa è troncata al tetto da una discordanza angolare che la separa da sedimenti conglomeratici e sabbiosi. Contemporaneamente, la tettonica estensionale interessa progressivamente la catena generando una serie di bacini intermontani, delimitati da faglie normali. I materiali di riempimento sono costituiti alla base da sedimenti grossolani che passano verso l’alto a depositi alluvionali e fluvio-lacustri. Nelle conche di Rieti e de L’Aquila, nei depositi lacustri, il ritrovamento di Equus stenonis e Mammuthus meridionalis, consente di riferire tali sedimenti ad un’età non più giovane del Pleistocene inferiore. Intorno a 0.8 Myr B.P., in concomitanza con un forte abbassamento relativo del livello di base, legato ad un subitaneo incremento del tasso di sollevamento, si verifica un più marcato arretramento delle linee di costa, accompagnato dalla messa in posto di depositi sabbioso-ciottolosi di ambiente litorale lungo i margini occidentale e orientale dell’Appennino. Contemporaneamente, un aumento del tasso di incisione fluviale dà origine al attuale sistema di valli, all’interno delle quali, per effetto dell’interazione tra l’aumento dell’erosione fluviale e le variazioni climatiche, si sono formati più ordini di terrazzi alluvionali. In tale contesto, l’erosione regressiva dei corsi d’acqua ha profondamente inciso le soglie della maggior parte dei bacini intermontani, prosciugando i laghi ed erodendo gran parte dei depositi presenti. In conclusione, in base a queste considerazioni si può ipotizzare che la crescita topografica della catena appenninica è stata lenta fino alla fine del Pleistocene inferiore, quando si è verificato un forte incremento del tasso di sollevamento.The central Apennines show geologic and geomorphic features that report the strong influence of extensional tectonics and regional uplift on their recent evolution. The goal of this paper is to find out the time constraints of the chain uplift, focusing on the elements of correlation between marine and continental successions on both the the Adriatic and Tyrrhenian flanks of the Apennines. All along the range, the most ancient landforms are gently rolling surfaces. On the western flank, the interaction between the uplift and the extensional tectonics related to the opening of the Tyrrhenian basin, generated several neoautoctonous basins that are older in Tuscany (since Tortonian) and younger in the Latium area (since Pliocene). On the Adriatic flank, the uplift of the chain, interacting with climatic changes, produced several sequences separated by angular unconformities. In the basins located along the western flank, progressively coarser sediments that correspond to the Globorotalia crassaformis biozone lay down. In particular, at Valle Ricca a 2.1 Myr old volcanic layer has been reported close to the top of these deposits and corresponds to the base of the Globorotalia inflata biozone. The Valle Ricca succession is truncated by an erosion surface over which marine and brackish sandy clay (Argille Sabbiose del Chiani-Tevere) lay down. Similarly, in the periadriatic basin, a volcanic layer, dated 2.1 Myr, has been found close to the top of a pelitic sequence at Bellante. At the top of this succession, an angular unconformity separates it from conglomerate and sand. This sequence records the progressively eastward shifting of the coastline as a consequence of the uplift. Contemporaneously, extensional tectonics progressively affected the Apennine chain giving rise to a number of intermontane basins, within which continental sediments such as conglomerate and clay were deposited. These basins are characterized by the deposition of coarse breccias, and lacustrine and alluvial deposits locally interfingered each other. In the Rieti and L’Aquila basins, in the lacustrine sediments, the finding of Equus stenonis and Mammuthus meridionalis allows to refer those deposits to an age older than lower Pleistocene. Around 0.8 Myr B.P., in correspondence with a base level drop induced by a sudden increase of uplift rate, the coastline strongly shifted seawards and littoral sand-pebble deposits lay down along the western and the eastern margins of the Apennines. After or contemporaneously, an increased stream erosion rate gave rise to the present valley network within which the interaction of river incision and climate changes generated several orders of alluvial terraces. In this contest, a hunched backward river erosion breached most of intramontane basins, draining off the lakes and causing the erosion of the basin sedimentary sequence. In conclusion, according to all these considerations we hypothesize that the topographic growth of the range was slow until the end of the lower Pleistocene, when a strong increase of the uplift rate affected the chain and the surrounding coastal belts
The differencial vertical movements between the Romanian Plain and the Subcarpathian Curvature: the geomorphological evolution of the contact area
No full textPermafrost-based geomorphology of the Mt. Foscagno - Mt. Forcellina ridge (Adda–Inn River basins, Central Italian Alps)
Full text linkThe permafrost-based geomorphological map of the Mt. Foscagno–Mt Forcellina ridge (Central Italian Alps) shows the distribution of permafrost probability (high, medium, low probability, and probable absence) obtained by the application of PERMACLIM (Guglielmin et al., 2003), a GIS-based model integrating Digital Elevation Model (DEM) topographic data and the Climatic DataBase (CDB) available from Automatic Weather Stations (AWS). In addition, the map provides information on the outcropping bedrock, the genesis and grain size of near-surface deposits, and geomorphological features with particular reference to periglacial and glacial landforms. Moreover, the map represents locations and values of ground measurements, Bottom Temperature of winter Snow cover (BTS) and Vertical Electric Soundings (VES), and the Mean Annual Air Temperature (MAAT; Guglielmin et al., 2003)
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