scholarly journals A model for the formation of the Pradol (Pradolino) dry valley in W Slovenia and NE Italy

Geologija ◽  
2021 ◽  
Vol 64 (1) ◽  
pp. 21-33
Author(s):  
Manuel DIERCKS ◽  
Christoph GRÜTZNER ◽  
Marko VRABEC ◽  
Kamil USTASZEWSKI
Keyword(s):  
Deformation Characteristic ◽  
Field Observations ◽  
River Diversion ◽  
Mountain Ranges ◽  
Ne Italy ◽  
River Terraces ◽  
Digital Elevation ◽  
Dry Valley ◽  
Tectonically Active ◽  
Fault Scarps

In tectonically active mountain ranges, the landscape is shaped by the interplay of erosion/sedimentation and tectonically driven crustal deformation. Characteristic landforms such as moraines, wind gaps, fault scarps, and river terraces can be used to decipher the landscape evolution. However, the available data often allow for different interpretations. Here we study the Pradol (Pradolino) Valley in Western Slovenia, a deeply incised canyon whose floor rests several hundreds of metres above the surrounding valleys. We use high-resolution digital elevation models, geomorphic indices and field observations to unravel the evolution of this peculiar landform. We present a six-stage evolution model of the canyon that includes the blockage of valleys by advancing glaciers, river diversion, and rapid incision due to a high discharge of post-glacial meltwater. The formation of the Pradol Valley was most likely facilitated by an underlying fault that serves as an easily erodible weakness zone in the Mesozoic limestones. Our model indicates that the formation of the canyon could have occurred during the last glaciation, which results in incision rates of several cm/yr. With the proposed model we can explain all remote and field observations available. Our study shows that a complex interplay of different landscape-shaping processes is needed to explain the occurrence of the Pradol dry valley and that rapid changes in the morphology occurred after the last glacial maximum.

scholarly journals Avalanche situation in Turkey and back calculation of selected events

2014 ◽  
Vol 14 (5) ◽  
pp. 1145-1154 ◽  
Author(s):  
A. Aydin ◽  
Y. Bühler ◽  
M. Christen ◽  
I. Gürer
Keyword(s):  
Simulation Software ◽  
High Mountain ◽  
Identification Algorithm ◽  
Black Sea Region ◽  
Mountain Ranges ◽  
Digital Elevation ◽  
Back Calculation ◽  
Elevation Model ◽  
Very High ◽  
Rapid Mass

Abstract. In Turkey, an average of 24 people die in snow avalanches every year, mainly in the eastern part of Anatolia and in the eastern Black Sea region, where high-mountain ranges are close to the sea. The proportion of people killed in buildings is very high (87%), especially in comparison to other European countries and North America. In this paper we discuss avalanche occurrence, the climatic situation and historical avalanche events in Turkey; in addition, we identify bottlenecks and suggest solutions to tackle avalanche problems. Furthermore, we have applied the numerical avalanche simulation software RAMMS (rapid mass movements simulation) combined with a (digital elevation model) DEM-based potential release zone identification algorithm to analyze the catastrophic avalanche events in the villages of Üzengili (Bayburt province) in 1993 and Yaylaönü (Trabzon province) in 1981. The results demonstrate the value of such an approach for regions with poor avalanche databases, enabling the calculation of different scenarios and the estimation of run-out distances, impact pressure and flow height.

scholarly journals Near-surface internal melting: a substantial mass loss on Antarctic Dry Valley glaciers

2014 ◽  
Vol 60 (220) ◽  
pp. 361-374 ◽  
Author(s):  
Matthew J. Hoffman ◽  
Andrew G. Fountain ◽  
Glen E. Liston
Keyword(s):  
Meteorological Data ◽  
Primary Source ◽  
Balance Model ◽  
Weathering Crust ◽  
Field Observations ◽  
Dry Valleys ◽  
Near Surface ◽  
Ice Surface ◽  
Dry Valley ◽  
Glacier Ablation

AbstractThe McMurdo Dry Valleys, southern Victoria Land, East Antarctica, are a polar desert, and melt from glacial ice is the primary source of water to streams, lakes and associated ecosystems. Previous work found that to adequately model glacier ablation and subsurface ice temperatures with a surface energy-balance model required including the transmission of solar radiation into the ice. Here we investigate the contribution of subsurface melt to the mass balance of (and runoff from) Dry Valley glaciers by including a drainage process in the model and applying the model to three glacier sites using 13 years of hourly meteorological data. Model results for the smooth glacier surfaces common to many glaciers in the Dry Valleys showed that sublimation was typically the largest component of surface lowering, with rare episodes of surface melting, consistent with anecdotal field observations. Results also showed extensive internal melting 5–15 cm below the ice surface, the drainage of which accounted for ~50% of summer ablation. This is consistent with field observations of subsurface streams and formation of a weathering crust. We identify an annual cycle of weathering crust formation in summer and its removal during the 10 months of winter sublimation.

New evidence of glacier surges in the Central Andes of Argentina and Chile

2018 ◽  
Vol 42 (6) ◽  
pp. 792-825 ◽  
Author(s):  
Daniel Falaschi ◽  
Tobias Bolch ◽  
Maria Gabriela Lenzano ◽  
Takeo Tadono ◽  
Andrés Lo Vecchio ◽  
...  
Keyword(s):  
Satellite Imagery ◽  
Remote Sensing Data ◽  
Central Andes ◽  
Aerial Images ◽  
Mountain Ranges ◽  
The Andes ◽  
Digital Elevation ◽  
Heterogeneous Behavior ◽  
Elevation Changes ◽  
Glacier Surges

In contrast to the large surge-type glacier clusters widely known for several mountain ranges around the world, the presence of surging glaciers in the Andes has been historically seen as marginal. The improved availability of satellite imagery during the last years facilitates investigating of glaciers in more detail even in remote areas. The purpose of the study was therefore to revisit existing information about surge-type glaciers for the Central Andes of Argentina and Chile (32° 40′–34° 20′ S), to identify and characterize possible further surge-type glaciers, providing new insights into the mass balance and evolution of the velocity of selected glaciers during the surge phase. Based on the analysis of 1962–2015 satellite imagery, historical aerial images, differencing of digital elevation models and a literature survey, we identified 21 surge-type glaciers in the study area. Eleven surge events and six possible surge-type glaciers were identified and described for the first time. The estimation of annual elevation changes of these glaciers for the 2000–2011 period, which encompasses the latest surge events in the region, showed heterogeneous behavior with strongly negative to positive surface elevation change patterns (−1.1 to +1.0 m yr−1). Additionally, we calculated maximum surface velocities of 3±1.9 m d−1 and 3.1±1.1 m d−1 for two of the glaciers during the latest identifiable surge events of 1985–1987 and 2003–2007. Within this glacier cluster, highly variable advance rates (0.01–1 km yr−1) and dissimilar surface velocities at the surge peak (3–35 m d−1) were observed. In comparison with other clusters worldwide, surge-type glaciers in the Central Andes are on average smaller and show minor absolute advances. Generally low velocities and the heterogeneous duration of the surge cycles are common between them and glaciers in the Karakorum, a region with similar climatic characteristics and many known surge-type glaciers. As a definitive assertion concerning the underlying surge mechanism of surges in the Central Andes could not be drawn based on the remote sensing data, this opens more detailed research avenues for surge-type glaciers in the region.

scholarly journals Climate controls on erosion in tectonically active landscapes

2020 ◽  
Vol 6 (42) ◽  
pp. eaaz3166 ◽  
Author(s):  
B. A. Adams ◽  
K. X. Whipple ◽  
A. M. Forte ◽  
A. M. Heimsath ◽  
K. V. Hodges
Keyword(s):  
Tectonic Evolution ◽  
Predictive Power ◽  
Annual Rainfall ◽  
Potential Influence ◽  
Ongoing Debate ◽  
Mountain Ranges ◽  
Erosion Rates ◽  
Tectonically Active ◽  
Climate Controls ◽  
The Himalaya

The ongoing debate about the nature of coupling between climate and tectonics in mountain ranges derives, in part, from an imperfect understanding of how topography, climate, erosion, and rock uplift are interrelated. Here, we demonstrate that erosion rate is nonlinearly related to fluvial relief with a proportionality set by mean annual rainfall. These relationships can be quantified for tectonically active landscapes, and calculations based on them enable estimation of erosion where observations are lacking. Tests of the predictive power of this relationship in the Himalaya, where erosion is well constrained, affirm the value of our approach. Our model allows estimation of erosion rates in fluvial landscapes using readily available datasets, and the underlying relationship between erosion and rainfall offers the promise of a deeper understanding of how climate and tectonic evolution affect erosion and topography in space and time and of the potential influence of climate on tectonics.

What controls erosion (exhumation) along the humid eastern margin of the Northern Andes? Insights from U-Th/He thermochronology

2020 ◽  
Author(s):  
Nicolas Perez-Consuegra ◽  
Edward R Sobel ◽  
Andres Mora ◽  
Jose R Sandoval ◽  
Paul G Fitzgerald ◽  
...  
Keyword(s):  
Middle Part ◽  
Tropical Regions ◽  
Northern Andes ◽  
Mountain Ranges ◽  
Mountainous Regions ◽  
Relative Contribution ◽  
Tectonically Active ◽  
Exhumation Rates ◽  
High Precipitation ◽  
Channel Steepness

<p>The relative controls of rock uplift (tectonics) and precipitation (climate) on the exhumation of earth’s rocks in tectonically active mountain ranges are still debated. In low latitude tropical regions where rates of precipitation and the amount of vegetation cover are higher, more data is required to test the relative contribution of these factors to the evolution of orogenic topography. To contribute to this debate, cooling ages were derived for 25 bedrock and four detrital samples using the apatite (U-Th-Sm)/He (AHe) low temperature thermochronometer. AHe ages are reported along a ~450-km-wide swath on the eastern flank of the Northern Andes in Colombia (South America). The AHe cooling ages, that range from 2.5 Ma to 17 Ma, are compared to precipitation rates and geomorphic parameters in order to discern the relative importance of climate and/or tectonics on exhumation. Along the transect, AHe cooling ages are poorly correlated with the rates of precipitation but show a good correlation with landscape parameters such as average hillslope and average channel steepness. Moreover, young AHe cooling ages coincide with areas where deformation is mainly compressional; older AHe cooling ages are found in the middle part of the study area where strike-slip deformation dominates. The spatial distribution of the new AHe cooling ages suggests that in mountainous regions, in this case with high precipitation rates (> 1500 mm/yr), denudation is mainly controlled by the rate of vertical advection of material via tectonic processes. The spatial variations in precipitation may only have a second-order role in modulating exhumation rates.</p>

scholarly journals Morphotectonic control of the Białka drainage basin (Central Carpathians): Insights from DEM and morphometric analysis.

2016 ◽  
Vol 5 (1) ◽  
pp. 61-82 ◽  
Author(s):  
Bartosz Wołosiewicz
Keyword(s):  
Drainage Basin ◽  
Research Area ◽  
Adjacent Area ◽  
Model Base ◽  
Base Level ◽  
Morphometric Analyses ◽  
Digital Elevation ◽  
Tectonically Active ◽  
Elevation Model ◽  
Central Carpathians

Abstract The Białka river valley is directly related to a deep NNW-SSE oriented fault zone. According to the results of previous morphometric analyses, the Białka drainage basin is one of the most tectonically active zones in the Central Carpathians. It is also located within an area of high seismic activity. In this study Digital Elevation Model (DEM) based, morphometric analyses were used to investigate the morphotectonic conditions of the watershed. The results reveal the relationships between the main tectonic feature and the landforms within the research area. The lineaments, as obtained from the classified aspect map, seem to coincide with the orientation of the main structures as well as the trends revealed by the theoretical Riedel-Skempton shear model. Base-level and isolong maps support the conclusion that the Białka and Biały Dunajec fault zones exert a strong influence on the morphology of the adjacent area.

scholarly journals Extração de Atributos Morfométricos da Serra Mossoró (Mossoró-RN) a Partir do Modelo de Elevação Digital (MDE)

2020 ◽  
Vol 12 (6) ◽  
pp. 2239
Author(s):  
Gutemberg Henrique Dias ◽  
João Paulo Bezerra Rodrigues ◽  
Francisco Sérgio Coelho ◽  
Robson Fernandes Filgueira ◽  
Filipe Silva Peixoto
Keyword(s):  
Digital Elevation Model ◽  
Sedimentary Basin ◽  
Rio Grande ◽  
Field Observations ◽  
Accurate Calculation ◽  
Mapping Software ◽  
Potiguar Basin ◽  
Digital Elevation ◽  
Elevation Model

Por possibilitar o cálculo rápido e preciso de variáveis associadas ao relevo, nas últimas décadas, o aprimoramento do Modelo Digital de Elevação (MDE) tem contribuído bastante para a pesquisa geomorfológica, particularmente em áreas de bacias sedimentares. No setor noroeste da Bacia Potiguar, no município de Mossoró, estado do Rio Grande do Norte, existe uma elevação que se destaca em meio ao relevo plano, conhecida como Serra Mossoró. Apesar da importância da região no que se refere à exploração de água subterrânea, prospecção de petróleo e fruticultura tropical, os trabalhos já produzidos sobre esta forma de relevo são escassos e superficiais. Este trabalho tem como objetivo realizar a extração de atributos morfométricos da Serra Mossoró e de suas adjacências a partir de Modelo de Elevação Digital (MDE), de modo a precisar a classificação deste relevo e correlaciona-lo com a neotectônica regional. Pesquisa bibliográfica, tratamento de imagens orbitais georreferenciadas com software de mapeamento e observações de campo possibilitaram a elaboração dos mapas hipsométrico, de relevo sombreado (hillshade) e clinométrico. A análise dos dados hipsométricos evidencia que a Serra Mossoró está estruturada em patamares e rampas, apresentando altimetria máxima de 268 metros. O mapa de relevo sombreado confirma a ocorrência de lineamentos  nos sentidos NE-SW e NW-SE, bem como, em menor proporção, no E-O, já descritos em outros trabalhos. Juntos, os mapas hipsométrico e de relevo sombreado definem a estrutura da Serra Mossoró como um inselberg de natureza sedimentar, resultante da erosão diferencial nas rochas da Bacia Potiguar.  Extraction of Morphometric Attributes from Serra Mossoró (Mossoró-RN) From the Digital Elevation Model (MDE) A B S T R A C TFor enabliling a rapid and accurate calculation of the variables associated to relief, in the last decades the enhancement of the Digital Elevation Model (DEM) has contributed greatly to geomorphological research, particularly in sedimentary basin areas. In the northwestern section of the Potiguar Basin, in the municipality of Mossoró, state of Rio Grande do Norte, there is an elevation that stands out in the middle of the flat relief known as Serra Mossoró. Despite the importance of the region in the exploration of groundwater, oil prospecting and tropical fruiticulture, the works already produced on this landform are scarce and superficial. From the analysis of morphometric attributes, this work aims to produce the DEM of Serra Mossoró and its surroundings, in order to clarify the classification of this relief and correlate it with the regional neotectonics. Bibliographical research, treatment of georeferenced orbital images with mapping software and field observations enabled the elaboration of the hypsometric, hillshade and clinometrical. The analysis of hypsometric data shows that Serra Mossoró is structured in steps and ramps, with a maximum altimetry of 268 meters. The hillshade map confirm the occurrence of lineaments in the NE-SW and NW-SE directions, as well as, to a lesser extent, in the E-O direction, already described in other works. Together, the hypsometric and hillshade maps define the Serra Mossoró structure as a sedimentary inselberg resulting from differential erosion in the rocks of the Potiguar Basin. Key words: Serra Mossoró, geologic-geomorphologic mapping, morphometric attributes, Digital Elevation Model

scholarly journals Megabeds in Istrian Flysch as markers of synsedimentary tectonics within the Dinaric foredeep (Croatia)

2021 ◽  
Vol 74 (2) ◽  
Author(s):  
Krešimir Petrinjak ◽  
◽  
Marko Budić ◽  
Stanislav Bergant ◽  
Tvrtko Korbar ◽  
...  
Keyword(s):  
Foreland Basin ◽  
Division I ◽  
Synsedimentary Tectonics ◽  
Sedimentary Evolution ◽  
The Matrix ◽  
Tectonically Active ◽  
Division Ii ◽  
Fault Scarps ◽  
Steep Slopes ◽  
Different Parts

Istrian Flysch was deposited during the Eocene in the Dinaric foredeep and is composed of hemipelagic marls and various gravity flow deposits. The latter are predominantly 5-40 cm thick turbidites, developed mostly as laminated and cross-rippled sandstone beds (Tb-e, Tc-e and Td-e Bouma sequences). In addition to the turbidites, there are deposits characterized by a significant thickness, occasionally more than 10 m, described as complex (bipartite) megabeds. The megabeds are composed of debrites in the lower part (Division I), and high-density turbidites in the upper part (Division II). The distinct clast composition of each megabed indicates that the lithoclasts were derived from tectonically active slopes and fault scarps along which collapses of the different parts of the Cretaceous to Palaeogene neritic carbonate succession, (that underlie the Flysch), occurred. The Division II deposits are well cemented, normally graded calcirudite/calcarenites composed mostly of orthophragminids, nummulitids, and red algae, originating from outer ramp environments. Redeposited marl, observed in the matrix of the debrites and as intraclasts in some megabeds, implies that the collapses along the synsedimentary fault scarps and steep slopes also occurred within the foredeep itself, during the rapid tectono-sedimentary evolution of the Dinaric foreland basin.

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