Tectonic and Climatic Inferences from the Terrace Staircase in the Meduna Valley, Eastern Southern Alps, NE Italy

2015 ◽  
Vol 83 (1) ◽  
pp. 229-242 ◽  
Author(s):  
Giovanni Monegato ◽  
Maria Eliana Poli
Keyword(s):  
Middle Miocene ◽  
Slip Rate ◽  
Southern Alps ◽  
Structural Element ◽  
Fluvial Terraces ◽  
Ne Italy ◽  
Thrust Front ◽  
Fold And Thrust Belt ◽  
Thrust System ◽  
Depositional Units

AbstractResults of stratigraphic and morphotectonic analyses on fluvial terraces at the outlet of the Meduna valley in the eastern Southern Alps are used to investigate on the tectonics and paleoclimate. The Meduna valley, prone to destructive earthquakes, belongs to the front of the eastern Southern Alps, a south-verging fold and thrust belt in evolution from the Middle Miocene to the present, constructed by ENE–WSW striking, SSE-verging medium to low-angle thrusts, gradually propagating in the Venetian–Friulian plain. In the study area, located south of the Periadriatic thrust, the main structural element is the ENE–WSW striking Maniago–M. Jouf thrust system. Seven depositional units, ranging in age from Pliocene to Holocene, and a hierarchy of four numbered terrace complexes were identified. Stratigraphic and geometric relationships between sedimentary units, basal surfaces and terraces allow the reconstruction of the chronology of the depositional events. The study shows that the valley configuration has been shaped during the Pliocene–Quaternary with long-lasting steady intervals, interspaced with periodic tectonic pulses of the thrust front of the eastern Southern Alps. The most recent pulse related to the Maniago thrust shows an upper Pleistocene–Holocene slip rate of about 0.6 mm/yr.

Uplift and active tectonics of southern Albania inferred from incision of alluvial terraces

2009 ◽  
Vol 71 (3) ◽  
pp. 465-476 ◽  
Author(s):  
J. Carcaillet ◽  
J.L. Mugnier ◽  
R. Koçi ◽  
F. Jouanne
Keyword(s):  
Active Faults ◽  
Active Tectonics ◽  
Slip Rate ◽  
Age Dating ◽  
Normal Faults ◽  
Published Data ◽  
Fluvial Terraces ◽  
Thrust System ◽  
Alluvial Terraces

AbstractIn Albania, the Osum and Vjoje rivers cross the active graben system and the active frontal thrust system of the Albanides. The effects of climatic and geodynamic forcing on the development of these two rivers were investigated by the means of field mapping, topographic surveying and absolute exposure-age dating. We established the chronology of terraces abandonment from the compilation of new dating (14C and in situ produced 10Be) and previously published data. We identified nine fluvial terraces units developed since Marine Isotope Stage 6 up to historic times. From this reconstituted history, we quantified the vertical uplift on a time scale shorter than the glacial climatic cycle. Regional bulging produces an overall increase of the incision rate from the west to the east that reaches a maximum value of 2.8 m/ka in the hinterland. Local pulses of incision are generated by activation of normal faults. The most active faults have a SW–NE trend and a vertical slip rate ranging from 1.8 to 2.2 m/ka. This study outlines the geodynamic control in the development of rivers flowing through the Albanides on the scale of 103–105ka.

scholarly journals Hillslope denudation and morphologic response to a rock uplift gradient

2020 ◽  
Vol 8 (2) ◽  
pp. 221-243 ◽  
Author(s):  
Vincent Godard ◽  
Jean-Claude Hippolyte ◽  
Edward Cushing ◽  
Nicolas Espurt ◽  
Jules Fleury ◽  
...  
Keyword(s):  
High Resolution ◽  
Strong Dependence ◽  
Digital Terrain Model ◽  
Slip Rate ◽  
Joint Analysis ◽  
Deformation Model ◽  
Base Level ◽  
Denudation Rates ◽  
Blind Thrust ◽  
Thrust System

Abstract. Documenting the spatial variability of tectonic processes from topography is routinely undertaken through the analysis of river profiles, since a direct relationship between fluvial gradient and rock uplift has been identified by incision models. Similarly, theoretical formulations of hillslope profiles predict a strong dependence on their base-level lowering rate, which in most situations is set by channel incision. However, the reduced sensitivity of near-threshold hillslopes and the limited availability of high-resolution topographic data has often been a major limitation for their use to investigate tectonic gradients. Here we combined high-resolution analysis of hillslope morphology and cosmogenic-nuclide-derived denudation rates to unravel the distribution of rock uplift across a blind thrust system at the southwestern Alpine front in France. Our study is located in the Mio-Pliocene Valensole molassic basin, where a series of folds and thrusts has deformed a plateau surface. We focused on a series of catchments aligned perpendicular to the main structures. Using a 1 m lidar digital terrain model, we extracted hillslope topographic properties such as hilltop curvature CHT and nondimensional erosion rates E∗. We observed systematic variation of these metrics coincident with the location of a major underlying thrust system identified by seismic surveys. Using a simple deformation model, the inversion of the E∗ pattern allows us to propose a location and dip for a blind thrust, which are consistent with available geological and geophysical data. We also sampled clasts from eroding conglomerates at several hilltop locations for 10Be and 26Al concentration measurements. Calculated hilltop denudation rates range from 40 to 120 mm kyr−1. These denudation rates appear to be correlated with E∗ and CHT that were extracted from the morphological analysis, and these rates are used to derive absolute estimates for the fault slip rate. This high-resolution hillslope analysis allows us to resolve short-wavelength variations in rock uplift that would not be possible to unravel using commonly used channel-profile-based methods. Our joint analysis of topography and geochronological data supports the interpretation of active thrusting at the southwestern Alpine front, and such approaches may bring crucial complementary constraints to morphotectonic analysis for the study of slowly slipping faults.

scholarly journals First evidence of active transpressive surface faulting at the front of the eastern Southern Alps, northeastern Italy. Insight on the 1511 earthquake seismotectonics

2018 ◽  
Author(s):  
Emanuela Falcucci ◽  
Maria Eliana Poli ◽  
Fabrizio Galadini ◽  
Giancarlo Scardia ◽  
Giovanni Paiero ◽  
...  
Keyword(s):  
Strike Slip ◽  
Southern Alps ◽  
Strike Slip Fault ◽  
Fault System ◽  
The Past ◽  
Fold And Thrust Belt ◽  
Northeastern Italy ◽  
Dextral Strike Slip Fault ◽  
Seismic Lines ◽  
Dextral Strike Slip

Abstract. We investigated the eastern corner of northeastern Italy, where the NW-SE trending dextral strike-slip fault systems of western Slovenia intersects the south-verging fold and thrust belt of the eastern Southern Alps . The area suffered the largest earthquakes of the region, among which are the 1511 (Mw 6.3) event and the two major shocks of the 1976 seismic sequence, with Mw = 6.4 and 6.1 respectively. The Colle Villano thrust and the Borgo Faris-Cividale strike-slip fault have been first analyzed by interpreting industrial seismic lines and then by performing morpho-tectonic and paleoseismological analyses. These different datasets indicate that the two structures define an active, coherent transpressive fault system that activated twice in the past two millennia, with the last event occurring around the 15th–17th century. The chronological information, and the location of the investigated fault system suggest its activation during the 1511 earthquake.

PALEOSEISMOLOGICAL INVESTIGATIONS AT THE FRONT OF THE EASTERN SOUTHERN ALPS (NE Italy)

2020 ◽  
Author(s):  
Giulia Patricelli ◽  
Maria Eliana Poli ◽  
Giovanni Paiero ◽  
Giovanni Monegato ◽  
Francesco Marinoni ◽  
...  
Keyword(s):  
Damage Zone ◽  
Southern Alps ◽  
Alluvial Fan ◽  
The South ◽  
Active Deformation ◽  
The North ◽  
Ne Italy ◽  
Structural Framework ◽  
Accademia Dei Lincei ◽  
The Village

<p>In the framework of the III level Seismic Microzonation of the Pieve del Grappa municipality (Treviso, NE Italy), three paleoseismological trenches were dug, in order to investigate activity and capacity of the Crespano del Grappa backthrust.</p><p>The study area is located in the Veneto foothills, where the Plio-Quaternary external front of the Eastern Southern Alps (Castellarin and Cantelli, 2000) presently propagates with a 2-3 mm/y velocity towards the south (Serpelloni et al., 2016). The external front is composed of a series of arcuated WSW-ENE striking, S verging structures (Galadini et al, 2005). Moreover, the area is characterized by a medium-to-low seismicity with only one M>6 earthquake during the last millennium: the 1695 Asolo event, Mw 6.45 (Rovida et al., 2016).</p><p>Regarding the structural framework, the study area is located between the Bassano-Vittorio Veneto Thrust to the north and the Bassano-Cornuda Thrust to the south. The investigated tectonic structure, i.e. the Bassano-Cornuda backthrust, is a N-verging E-W striking reverse structure. Moving from east to the west, it widely crops out near the Castelcucco village, causing a hundred meters displacement in the Miocene Molasse (Braga, 1970). In particular in Crespano village the thrust is responsible of an about 10 m vertical throw in the Quaternary alluvial conglomerates of Lastego river (Parinetto, 1987). Because of the urbanization, the paleoseismological trenches were realized at the eastern (Col Canil) and western (San Vito) borders of the village. In the former case, the trench cut through thick colluvial deposits that probably buried an abandoned valley. Differently, the second and the third trenches affected wide coalescent LGM alluvial fans, which border the southern slope of Mt. Grappa.</p><p>The results testify an intense Pleistocene-Holocene deformation of the Crespano del Grappa backthrust. Particularly, active deformation evidence deals with:</p><ul><li>back-tilting of the Holocene colluvial units;</li> <li>pronounced polyphasic liquefaction episodes, locally completely altering the sedimentary structures of colluvial units;</li> <li>a wide damage zone in the proximity of the morphological scarp and associated with the peak of the induced polarization. This observation testifies that the Crespano del Grappa backthrust reached the surface and displaced topography in the past, probably at the occurrence of one or more events which generated the paleoliquefaction effects;</li> <li>the 3-4 m displacement of the LGM alluvial fan deposits.</li> </ul><p>Concerning the age of the deformation, the dating of the involved units suggests a post LGM activation, probably recent-to-historical.</p><p> </p><p>REFERENCES</p><p>Braga GP, 1970. Rendiconti Fisici dell’Accademia dei Lincei, serie 8, 48(4): 451-455.</p><p>Castellarin A. and Cantelli L., 2000. Journal of Geodynamics. DOI: 10.1016/S0264-3707(99)00036-8.</p><p>Galadini et al., 2005. Geophysical Journal International. DOI: 10.1111/j.1365-246X.2005.02571.x.</p><p>Parinetto A., 1987. Aspetti morfotettonici del versante meridionale del Grappa e delle colline antistanti. Unpublished degree thesis. University of Padova, Italy.</p><p>Rovida et al., 2016. DOI: http://doi.org/10.6092/INGV.IT-CPTI15.</p><p>Serpelloni et al., 2016. Tectonophysics, https://doi.org/10.1016/j.tecto.2016.09.026.</p>

scholarly journals Volatile-rich melts as markers of the asthenospheric influx prior to rifting events: the case of the alkaline-carbonatitic lamprophyres of the Dolomitic Area (Southern Alps, Italy)

2020 ◽  
Author(s):  
Federico Casetta ◽  
Ryan B. Ickert ◽  
Darren F. Mark ◽  
Costanza Bonadiman ◽  
Pier Paolo Giacomoni ◽  
...  
Keyword(s):  
Partial Melting ◽  
Large Scale ◽  
Southern Alps ◽  
Ne Italy ◽  
Enriched Mantle ◽  
New Findings ◽  
Geodynamic Processes ◽  
Alkaline Magmas ◽  
And Behavior

<p>The appearance of alkali- and volatile-rich melts often marks the opening of major magmatic cycles, always reflecting the partial melting of heterogeneously enriched mantle domains. In these cases the study of highly alkaline, H<sub>2</sub>O-CO<sub>2</sub>-rich magmatic pulses provide important insights on the composition and behavior of the sub-continental lithospheric mantle (SCLM) prior to rift initiation. The camptonitic dykes cropping out at Predazzo (Dolomitic Area, NE Italy) are among the oldest examples of lamprophyric rocks in Italy, and were historically related to the orogenic-like Middle Triassic magmatism of the Southern Alps. A detailed petrological, geochemical and geochronological characterization of these rocks was developed to frame them inside the articulated geodynamic evolution of the Southern Alps domain during Triassic. Whole-rock and mineral phase geochemistry, together with <sup>40</sup>Ar/<sup>39</sup>Ar data showed that Predazzo lamprophyres represent an alkaline-carbonatitic magmatic event temporally isolated (~220 Ma) from the major Ladinian orogenic-like magmatism of the Southern Alps (~238 Ma). Lamprophyres can thus be attributed to the volumetrically limited alkaline magmatic phase that infiltrated several portions of the Southern Alps lithosphere between 225 and 190 Ma. Partial melting models and Sr-Nd isotopes demonstrate that Predazzo lamprophyres were produced by low partial melting degree of a garnet-amphibole-bearing mantle source interacting with a significant asthenospheric contribution. In the light of these new findings, they are interpreted as the geochemical/geochronological bridge between the orogenic-like Ladinian magmatism and the rifting phase related to the opening of the Alpine Tethys. This study highlights the paramount importance of alkaline magmas for tracking the volatiles cycle in the SCLM and the potential lithosphere-asthenosphere interactions during large-scale geodynamic processes.</p>

scholarly journals New insights into active tectonics and seismogenic potential of the Italian Southern Alps from vertical geodetic velocities

Solid Earth ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 1681-1698 ◽  
Author(s):  
Letizia Anderlini ◽  
Enrico Serpelloni ◽  
Cristiano Tolomei ◽  
Paolo Marco De Martini ◽  
Giuseppe Pezzo ◽  
...  
Keyword(s):  
Velocity Gradient ◽  
Active Tectonics ◽  
Slip Rate ◽  
Southern Alps ◽  
Dislocation Model ◽  
Strain Accumulation ◽  
Plate Convergence ◽  
Mountain Front ◽  
Northeastern Italy ◽  
Gps Velocities

Abstract. This study presents and discusses horizontal and vertical geodetic velocities for a low strain rate region of the south Alpine thrust front in northeastern Italy obtained by integrating GPS, interferometric synthetic aperture radar (InSAR) and leveling data. The area is characterized by the presence of subparallel, south-verging thrusts whose seismogenic potential is still poorly known. Horizontal GPS velocities show that this sector of the eastern Southern Alps is undergoing ∼1 mm a−1 of NW–SE shortening associated with the Adria–Eurasia plate convergence, but the horizontal GPS velocity gradient across the mountain front provides limited constraints on the geometry and slip rate of the several subparallel thrusts. In terms of vertical velocities, the three geodetic methods provide consistent results showing a positive velocity gradient, of ∼ 1.5 mm a−1, across the mountain front, which can hardly be explained solely by isostatic processes. We developed an interseismic dislocation model whose geometry is constrained by available subsurface geological reconstructions and instrumental seismicity. While a fraction of the measured uplift can be attributed to glacial and erosional isostatic processes, our results suggest that interseismic strain accumulation at the Montello and the Bassano–Valdobbiadene thrusts it significantly contributing to the measured uplift. The seismogenic potential of the Montello thrust turns out to be smaller than that of the Bassano–Valdobbiadene fault, whose estimated parameters (locking depth equals 9.1 km and slip rate equals 2.1 mm a−1) indicate a structure capable of potentially generating a Mw>6.5 earthquake. These results demonstrate the importance of precise vertical ground velocity data for modeling interseismic strain accumulation in slowly deforming regions where seismological and geomorphological evidence of active tectonics is often scarce or not conclusive.

scholarly journals New insights into active tectonics and seismogenic potential of the Italian Southern Alps from vertical geodetic velocities

2020 ◽  
Author(s):  
Letizia Anderlini ◽  
Enrico Serpelloni ◽  
Cristiano Tolomei ◽  
Paolo Marco De Martini ◽  
Giuseppe Pezzo ◽  
...  
Keyword(s):  
Velocity Gradient ◽  
Active Tectonics ◽  
Slip Rate ◽  
Southern Alps ◽  
Dislocation Model ◽  
Strain Accumulation ◽  
Plate Convergence ◽  
Mountain Front ◽  
Northeastern Italy ◽  
Gps Velocities

Abstract. This study presents and discusses horizontal and vertical geodetic velocities for a low strain-rate region of the Southalpine thrust front in northeastern Italy obtained by integrating GPS, InSAR and leveling data. The area is characterized by the presence of sub-parallel, south verging thrusts, whose seismogenic potential is still poorly known. Horizontal GPS velocities show that this sector of the Eastern Southern Alps is undergoing ~ 1 mm/a of NW-SE shortening associated with the Adria-Eurasia plate convergence, but the horizontal GPS velocity gradient across the mountain front provide limited constraints on the geometry and slip-rate of the several sub-parallel thrusts. In terms of vertical velocities, the three geodetic methods provide consistent results showing a positive velocity gradient, of ~ 1.5 mm/a, across the mountain front, which can be hardly explained solely by isostatic processes. We developed a interseismic dislocation model, whose geometry is constrained by available subsurface geological reconstructions and instrumental seismicity. While a fraction of the measured uplift can be attributed to glacial and erosional isostatic processes, our results suggest that interseismic strain accumulation at the Montello and the Bassano-Valdobbiadene thrusts are significantly contributing to the measured uplift. The seismogenic potential of the Montello thrust turns out to be smaller than that of the Bassano-Valdobbiadene fault, whose estimated parameters (LD = 9.1 km and slip-rate = 2.1 mm/a) indicate a structure capable of potentially generating a Mw > 6.5 earthquake. These results demonstrate the importance of precise vertical ground velocity data for modeling interseismic strain accumulation in slowly deforming regions, where often seismological and geomorphological evidence of active tectonics is scarce or not conclusive.

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