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The tectonic influence on drainage evolution in an uplifting area: the case of the Sila Greca (Calabria, Italy)
No full text""La Sila (Calabria, Italia meridionale) è un massiccio caratterizzato da un altopiano dolcemente ondulato a circa 1000-1900 m di quota. Il Massiccio della Sila, costituito da rocce cristalline e metamorfiche sovrascorse su carbonati e depositi silico-clastici mesozoici, è circondato da bacini estensionali. In questi affiorano depositi marini e continentali di età variabile dal Tortoniano all’Olocene. Dalla fine del Pleistocene inferiore, la Sila è stata interessata da un sollevamento regionale, come testimoniato dalle valli fluviali profondamente incise e dai terrazzi marini. La superficie a basso rilievo locale ubicata sull’altopiano silano rappresenta ciò che resta di un antico paesaggio sviluppatosi prima del sollevamento quaternario, in condizioni di relativa stabilità del livello di base. È stata esaminata la morfotettonica di un’area che si estende dalle pendici settentrionali del massiccio fino al suo interno, dove si trova il Lago Cecita. Lo studio si è focalizzato su analisi morfometriche della topografia generale e dei bacini di drenaggio, su attività di terreno e fotointerpretazione. Il fine è di indagare le evidenze dell’influenza della tettonica locale sull’evoluzione del sistema idrografico della Sila settentrionale, nel contesto del sollevamento dell’Arco Calabro. I risultati indicano che, sebbene il sollevamento regionale abbia indotto una forte incisione, l’evoluzione del drenaggio è stata fortemente condizionata dalla tettonica locale. In particolare, viene proposto di estendere verso nord la Faglia del Lago Cecita, considerata in letteratura attiva nel Quaternario e caratterizzata da microsismicità. Questo sistema ha riorganizzato il drenaggio della Sila settentrionale, abbassandone la porzione occidentale.""""The Sila Massif (Calabria, southern Italy) is a high-standing plateau with a rolling upland surface lying between 1000 and 1900 m. It is underlain by magmatic and metamorphic rocks thrusted over Mesozoic carbonate and terrigenous units. The Sila Massif is surrounded by low-standing extensional basins, filled with several upper Tortonian to Holocene marine and fluvial deposits. Since the end of the early Pleistocene, the Sila Massif has been uplifted regionally as indicated by deeply incised river valleys and flights of marine terraces. The low-relief Sila upland surface is the remnants of a pre-uplifted landscape developed during a long time of stable base level. Our study examines the tectonic geomorphology of an area extending from the northern flank of the massif to its interiors including the Cecita Lake. We focused on the general topographic metrics, drainage patterns, and river long profiles, based on field surveys and aerial-photo interpretation. Our goal was to investigate the local tectonic constrains on the evolution of northern Sila drainage network in the context of the Calabrian Arc uplift. Our results indicate that the drainage evolution has been strongly controlled primarily by local tectonics and secondarily by regional uplift. In particular, we suggest that the northward continuation of the informally-named Cecita Lake Fault has recently reorganized the northern Sila drainage by west-side down subsidence of the hanging wall. This segment of the Cecita Lake Fault is considered by some researchers to be active in the Quaternary by offset stratigraphy as well as by proximal microseismic activity."
Comment on: “Geomorphological, paleontological and 87Sr/86Sr isotope analyses of early Pleistocene paleoshorelines to define the uplift of Central Apennines (Italy)”
No full textDrainage system adjustment in response to the opening of the Rieti intermontane basin (Central Italy): geostatistical reconstruction of the PaleoFarfa River alluvial plain
No full textLandscape evolution in the context of the Quaternary uplift of the Apennines: the changes of the hydrographic network of the Corno River (central Italy)
No full textGeologic and geomorphic data suggest that the topographic growth of the Apennines has been very slow during the crustal shortening phase (Miocene-Pliocene) and greatly accelerated in the Quaternary. Such different uplift rates should have generated peculiar landforms that preserve information regarding the long-term evolution of the landscape. In this framework, we studied the geomorphology of the Corno River drainage basin, focusing on low local relief surfaces and on the river network features. The drainage basin of the Corno River is underlain by overthrusted Tertiary carbonates and marls, that have been offset by normal faults since the end of Pliocene. The topography of the study area is characterized, at elevation between 1000 and 1150 m, by low local relief surfaces, bordered by fluvial or structural steep scarps and locally offset by faults. In the study area extension generated three intermontane basins (Leonessa, Cascia and Norcia), drained by the Corno River and its tributaries. The Cascia and Norcia basins show a higher residual relief with respect to Leonessa basin, reflecting the progressive action of the headward river erosion and its interaction with the activity of the bordering faults. The Corno network appears to be more strongly influenced by faults that generate abrupt changes of the main trunk direction and knickpoints in its long profile. Except in the Leonessa depression and close to Cascia, the river flows in a very narrow and deep valley, showing locally entrenched meanders. Four orders of fluvial terraces have been found, although only the youngest one is widely preserved. On the valley slopes, at elevation between 50 and 170 m above the present valley bottom, we found out several subhorizontal surfaces that could be straths. We interpret the low relief surfaces as relics of an old landscape with relief lower than present, graded to or near base level. This landscape was drained by a river network characterized by wide valleys and internally-drained basins (the intermontane depressions). As a consequence of the strong increase of the uplift rate at the end of lower Pleistocene, the lowering of the base level induced a general deepening and a new organization of Corno basin network, commonly influenced by faults. Alluvial terrace and strath formation follows the general model of hillslope and watershed response to Quaternary climatic changes
Morphometric evidences of the topographic growth of the central Apennines
No full textIn active tectonic regions, topography results from the interaction between tectonics and surface processes. Geologic and geomorphic data suggest that the topographic growth of the Apennines was slow during the phase of crustal shortening (Miocene¡VPliocene), but accelerated in the Quaternary, when the tectonics was dominated by extension. Such disparate uplift rates should impart a unique fingerprint in 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 (20-30 km wide spacing), linked to local tectonic structures, and a long one that corresponds to a broad topographic bulge ƒî250 km wide, that records a regional uplift. As a response the rivers incised the topography of the growing chain mostly the same. In particular, on the Tyrrhenian side, the rectangular drainage pattern, and knickpoint in the long profiles suggest the strong influenced of the extensional tectonics. The rivers draining to the Adriatic Sea, that deeply incised gorges, show long profiles with knickpoints that correspond to rock changes. 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 highest one is located at the crest of the chain cutting across carbonates. The lower surface is inset into the flanks of the range and cut across turbidites. A third geomorphic surface, located more eastward, is underlain by Pliocene and Quaternary deposits. These geomorphic surfaces and distribution of the Pliocene deposits indicate that during slow emergence of the chain in the late Tertiary, surface processes shaped a low relief landscape that is preserved today as the summit surface. On the Adriatic side, the main trunks of the rivers progressively incised perpendicular to the compressive structures. Conversely, on the Tyrrhenian side, the influence of the active extension induced the formation of a rectangular network and locally internally-drained basins. Successively, during the Quaternary, the rivers, as a consequence of the ~250 km wide bulge uplift, deeply cut down the more emerged portions of the chain
Carta Geologica del Quaternario del bacino di Leonessa (Rieti) - Geological map of the Quaternary deposits of the Leonessa basin (Rieti)
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