scholarly journals Origin of Knickpoints in an Alpine Context Subject to Different Perturbing Factors, Stura Valley, Maritime Alps (North-Western Italy)

Geosciences ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 443 ◽  
Author(s):  
Monica Marrucci ◽  
Gerold Zeilinger ◽  
Adriano Ribolini ◽  
Wolfgang Schwanghart

Natural catchments are likely to show the existence of knickpoints in their river networks. The origin and genesis of the knickpoints can be manifold, considering that the present morphology is the result of the interactions of different factors such as tectonic movements, quaternary glaciations, river captures, variable lithology, and base-level changes. We analyzed the longitudinal profiles of the river channels in the Stura di Demonte Valley (Maritime Alps) to identify the knickpoints of such an alpine setting and to characterize their origins. The distribution and the geometry of stream profiles were used to identify the possible causes of the changes in stream gradients and to define zones with genetically linked knickpoints. Knickpoints are key geomorphological features for reconstructing the evolution of fluvial dissected basins, when the different perturbing factors affecting the ideally graded fluvial system have been detected. This study shows that even in a regionally small area, perturbations of river profiles are caused by multiple factors. Thus, attributing (automatically)-extracted knickpoints solely to one factor, can potentially lead to incomplete interpretations of catchment evolution.

2016 ◽  
Vol 4 (1) ◽  
pp. 11-23 ◽  
Author(s):  
J.-L. Grimaud ◽  
C. Paola ◽  
V. Voller

Abstract. Knickpoints are fascinating and common geomorphic features whose dynamics influence the development of landscapes and source-to-sink systems – in particular the upstream propagation of erosion. Here, we study river profiles and associated knickpoints experimentally in a microflume filled with a cohesive substrate made of silica, water and kaolinite. We focus on the effect on knickpoint dynamics of varying the distribution of base-level fall (rate, increment, and period) and substrate strength, i.e., kaolinite content. Such simple cases are directly comparable to both bedrock and alluvial river systems. Under a constant rate of base-level fall, knickpoints of similar shape are periodically generated, highlighting self-organized dynamics in which steady forcing leads to multiple knickpoint events. Temporary shielding of the bed by alluvium controls the spacing between these unit knickpoints. Shielding is, however, not effective when base-level drops exceed alluvium thickness. While the base-level fall rate controls the overall slope of experiments, it is not instrumental in dictating the major characteristics of unit knickpoints. Instead the velocity, face slope and associated plunge pool depth of these knickpoints are all strongly influenced by lithology. The period between knickpoints is set by both alluvium thickness and base-level fall rate, allowing use of knickpoint spacing along rivers as an indicator of base-level fall rate.


2021 ◽  
pp. 199-223
Author(s):  
Ekaterina Litvinenko

The aim of the study is to assess the innovative potential of housing construction through determining the purchasing power of citizens acquiring housing in the property. In terms of hypothesis the study offers the term of acquiring housing in property as a criterion for this assessment. This indicator displays the change in the purchasing power of citizens under the influence of various externalities. The analysis of this indicator allows us to determine the influence of these factors on the change in the purchasing power of population, to identify the reserves that contribute to its increase, and to identify the policies aimed at innovative development of construction industry. The article assesses the innovative development of housing through an in-depth analysis of factors affecting the change in the term of housing acquisition in the Russian Federation at large, as well as in the context of individual subjects of the Central and North-Western Federal Districts of Russia in the period from 2017 to 2018.


2020 ◽  
Vol 163 ◽  
pp. 03002
Author(s):  
Vasiliy Dmitriev ◽  
Svetlana Sedova ◽  
Anastasiia Plenkina ◽  
Viktoriia Khomiakova ◽  
Diana Avdeevich ◽  
...  

By the example of the Suuri Lake (0.37 km2) situated in the North-Western Ladoga region, modern aspects of monitoring the ecological state of water bodies are generalized, including 1) assessment of the rates of mass transfer processes in water ecosystems and the factors affecting them; 2) assessment of the integrated properties of water bodies and their ecosystems based on hierarchical schemes summarizing information about the state of subsystems and their properties in the form of composite indices. The results of the study in 2019 are visualized. Quantitative estimates of the chemical and biological composition and physical properties of the aquatic ecosystem, mass transfer rates, factors influencing them are obtained; the values of the integral indicators for the subsystem and their properties (productivity, water quality, stability) and the integral indicators of the systems and their integrative properties as a whole (ecological status, ecological wellbeing) are estimated. The temporal dynamics of the processes, component composition and complex properties of the aquatic ecosystem are investigated.


2020 ◽  
Author(s):  
Andreas Ludwig ◽  
Wolfgang Schwanghart ◽  
Florian Kober ◽  
Angela Landgraf

<p>The topographic evolution of landscapes strongly depends on the resistance of bedrock to erosion. Detachment-limited fluvial landscapes are commonly analyzed and modelled with the stream power incision model (SPIM) which parametrizes erosional efficiency by the bulk parameter K whose value is largely determined by bedrock erodibility. Inversion of the SPIM using longitudinal river profiles enables resolving values of K if histories of rock-uplift or base level change are known. Here, we present an approach to estimate K-values for the Wutach catchment, southern Germany. The catchment is a prominent example of river piracy that occurred ~18 ka ago as response to headward erosion of a tributary to the Rhine. Base level fall of up to 170 m triggered a wave of upstream migrating knickpoints that represent markers for the transient response of the landscape. Knickpoint migration along the main trunk stream and its tributaries passed different lithological settings, which allows us to estimate K for crystalline and sedimentary bedrock units of variable erodibility.</p>


2016 ◽  
Vol 66 (3) ◽  
pp. 543-561 ◽  
Author(s):  
Ewa Falkowska ◽  
Tomasz Falkowski ◽  
Andrzej Tatur ◽  
Agnieszka Kałmykow-Piwińska

Abstract Geological and geochemical investigations were carried out in the floodplain of the Vistula River Valley gorge near Solec nad Wisłą (Małopolska Gorge of the Vistula River). Geological mapping was supported by DEM and remote sensing analysis. Sediment samples were taken from depths of 0.5 m and 1.5 m from all geomorphological features identified. The geochemical analysis included determination of Cr, V, Sr, Ba, Ni, Cu, Co, As, Pb and Zn concentrations. Results indicate that the main factors affecting the pattern of features in the floodplain of this area are (1) the highly dynamic flood flow in the narrow section of the gorge and (2) the relief of the top surface of the sub-alluvial basement. The variable concentrations of trace elements are closely related to the floodplain features. Their concentrations can be considered as valuable geochemical proxies that enable a more thorough reconstruction of the sedimentary evolution of the Vistula River Valley and other similar river valleys, especially in gorge sections.


Geologos ◽  
2012 ◽  
Vol 18 (3) ◽  
pp. 135-161 ◽  
Author(s):  
Maria I. Waksmundzka

Abstract Fining-upwards cyclothems found in five boreholes in the Carboniferous (Lower Bashkirian) of the Lublin Basin were analysed sedimentologically. It was established that the cyclothems represent fluvial deposits, and the lithofacies were grouped into lithofacies associations. Most lithofacies associations represent three types of sand-bed braided rivers: (1) high-energy, (2) deep and (3) distal sheetflood-affected. Other associations represent hyperconcentrated flows. Both coarse-grained (type I) and fine-grained (types IIa and IIb) occur among the fining-upward cyclothems. The formation of most thick cyclothems was related mainly to allocyclic factors, i.e. a decrease in the river’s gradient. The thickest fining-upward cyclothems are characteristic of hyperconcentrated flows and braided-river channels. The aggradation ratios were commonly high. During the early Namurian C and early Westphalian A (Early Bashkirian), the eastern part of the Lublin Basin was located close to the source area. The sedimentary succession developed due to a transition from high-energy braidedrivers and hyperconcentrated flows to lower-energy braided rivers, controlled by a rise of the regional base level.


Lithosphere ◽  
2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Ian P. Armstrong ◽  
Brian J. Yanites ◽  
Nate Mitchell ◽  
Clarke DeLisle ◽  
Bruce J. Douglas

Abstract Over the past few decades, tectonic geomorphology has been widely implemented to constrain spatial and temporal patterns of fault slip, especially where existing geologic or geodetic data are poor. We apply this practice along the eastern margin of Bull Mountain, Southwest Montana, where 15 transient channels are eroding into the flat, upstream relict landscape in response to an ongoing period of increased base level fall along the Western North Boulder fault. We aim to improve constraints on the spatial and temporal slip rates across the Western North Boulder fault zone by applying channel morphometrics, cosmogenic erosion rates, bedrock characteristics, and calibrated reproductions of the modern river profiles using a 1-dimensional stream power incision model that undergoes a change in the rate of base level fall. We perform over 104 base level fall simulations to explore a wide range of fault slip dynamics and stream power parameters. Our best fit simulations suggest that the Western North Boulder fault started as individual fault segments along the middle to southern regions of Bull Mountain that nucleated around 6.2 to 2.5 Ma, respectively. This was followed by the nucleation of fault segments in the northern region around 1.5 to 0.4 Ma. We recreate the evolution of the Western North Boulder fault to show that through time, these individual segments propagate at the fault tips and link together to span over 40 km, with a maximum slip of 462 m in the central portion of the fault. Fault slip rates range from 0.02 to 0.45 mm/yr along strike and are consistent with estimates for other active faults in the region. We find that the timing of fault initiation coincides well with the migration of the Yellowstone hotspot across the nearby Idaho-Montana border and thus attribute the initiation of extension to the crustal bulge from the migrating hotspot. Overall, we provide the first quantitative constraints on fault initiation and evolution of the Western North Boulder fault, perhaps the farthest north basin in the Northern Basin and Range province that such constraints exist. We show that river profiles are powerful tools for documenting the spatial and temporal patterns of normal fault evolution, especially where other geologic/geodetic methods are limited, proving to be a vital tool for accurate tectonic hazard assessments.


2021 ◽  
Author(s):  
Edward R. Sobel ◽  
Rasmus Thiede ◽  
Paolo Ballato ◽  
Konstanze Stübner ◽  
Jonas Kley ◽  
...  

<p>The Pamir forms the northwestern tail of the Tibetan plateau and is a first-order tectonic feature of the Cenozoic Indo-Eurasian collision. The nature of the topographic uplift and orogenic growth of the entire northwestern margin of the Pamir is poorly constrained; however, this history can provide important constraints that are required to test geodynamic models of the tectonic evolution of the Pamir. Here we focus on the uplift history of the western and northwestern unglaciated margin of the Northern Pamir, the Darvaz and the Peter-the-First Ranges. These three ranges were formed by three major fault systems: the Main Pamir Thrust (MPT), the Darvaz and the Vakhsh fault zones (DFZ, VFZ). To assess the impact of tectonic uplift on the geomorphic evolution, we analyzed geomorphic characteristics of the topography, the longitudinal river profiles and the relief. To better constrain the regional crustal cooling history and uplift, we obtained thermochronologic cooling ages from the three regions.</p><p>We present 19 new zircon (U-Th-Sm)/He (ZHe) ages, 7 apatite fission track (AFT) ages, and 4 apatite (U-Th-Sm)/He (AHe) ages, ranging between >200 and 4 Ma, 14 and 4 Ma, and 15 and 3 Ma, respectively. The three units are characterized by unique Neogene cooling pathways, suggesting that they exhumed independently.</p><p>We discovered extensive low-relief landscapes with Neogene sedimentary cover uplifted ~2 km in elevation above the present-day regional base level. Our analysis indicates that the Panj and Vakhsh rivers form the regional base levels for the river network draining the entire northern and western margin of the Pamir. In the hanging wall of DFZ, the Paleozoic bedrock is characterized by significant relief (>1 km), the Neogene cover onlaps directly onto this Paleozoic bedrock. The tributary rivers crossing these landscapes are characterized by gentle, concave upstream longitudinal profiles at high elevation. These are interrupted by major knickpoint zones and steep downstream segments draining towards the deeply incised Panj and Vakhsh rivers. This indicates that the Darvaz Fault hanging wall had been uplifted and eroded prior to deposition of upper Neogene sediments, suggesting that the DFZ has a prolonged Neogene slip history. In contrast to the northeastern Pamir, here, the MPT-hanging-wall is characterized by reset late Oligocene-Early Miocene ZHe cooling ages ranging between 26 and 17 Ma. AFT and AHe-ages between 15 and 13 Ma suggest that exhumation suddenly terminated during the middle Miocene. In contrast, Jurassic sandstones exposed near the DFZ yield mostly un-reset Triassic-Jurassic ZHe ages (~250-170 Ma), a reset AFT age of ~5 Ma and a 2.5 Ma AHe age. Within the Peter-the-1st-Range, we obtained fully reset ~ 5 Ma ZHe ages, and ~4 Ma AFT ages. The rapid cooling trends since at least ~5 Ma suggest that deformation and a significant portion of crustal shortening propagated into the Tadjik foreland basin, causing enhanced uplift and erosion of the hanging wall of the VFZ and related faults. This deformation triggered ~2 km uplift of the entire northwest Pamir, recorded in uplifted paleo-landscapes and dissected tributaries of the Panj and Vakhsh rivers.</p>


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