scholarly journals Glaciation's topographic control on Holocene erosion at the eastern edge of the Alps

2016 ◽  
Vol 4 (4) ◽  
pp. 895-909 ◽  
Author(s):  
Jean L. Dixon ◽  
Friedhelm von Blanckenburg ◽  
Kurt Stüwe ◽  
Marcus Christl
Keyword(s):  
Eastern Alps ◽  
European Alps ◽  
Glacial Erosion ◽  
Erosion Rates ◽  
The Alps ◽  
Glacial Processes ◽  
Cosmogenic 10Be ◽  
Topographic Forcing ◽  
Eastern Edge

Abstract. What is the influence of glacial processes in driving erosion and uplift across the European Alps? It has largely been argued that repeated erosion and glaciation sustain isostatic uplift and topography in a decaying orogen. But some parts of the Alps may still be actively uplifting via deep lithospheric processes. We add insight to this debate by isolating the role of post-glacial topographic forcing on erosion rates. To do this, we quantify the topographic signature of past glaciation on millennial-scale erosion rates in previously glaciated and unglaciated catchments at the easternmost edge of the Austrian Alps. Newly measured catchment-wide erosion rates, determined from cosmogenic 10Be in river-borne quartz, correlate with basin relief and mean slope. GIS-derived slope–elevation and slope–area distributions across catchments provide clear topographic indicators of the degree of glacial preconditioning, which further correlates with erosion rates. Erosion rates in the easternmost, non-glaciated basins range from 40 to 150 mm ky−1 and likely reflect underlying tectonic forcings in this region, which have previously been attributed to recent (post 5 Ma) uplift. By contrast, erosion rates in previously glaciated catchments range from 170 to 240 mm ky−1 and reflect the erosional response to local topographic preconditioning by repeated glaciations. Together, these data suggest that Holocene erosion across the Eastern Alps is strongly shaped by the local topography relict from previous glaciations. Broader, landscape-wide forcings, such as the widely debated deep mantle-driven or isostatically driven uplift, result in lesser controls on both topography and erosion rates in this region. Comparing our data to previously published erosion rates across the Alps, we show that post-glacial erosion rates vary across more than 2 orders of magnitude. This high variation in post-glacial erosion may reflect combined effects of direct tectonic and modern climatic forcings but is strongly overprinted by past glacial climate and its topographic legacy.

scholarly journals Glaciation's topographic control on Holocene erosion at the eastern edge of the Alps

2016 ◽  
Author(s):  
Jean L. Dixon ◽  
Friedhelm von Blanckenburg ◽  
Kurt Stüwe ◽  
Marcus Cristl
Keyword(s):  
Eastern Alps ◽  
European Alps ◽  
Glacial Erosion ◽  
Erosion Rates ◽  
The Alps ◽  
Glacial Processes ◽  
Cosmogenic 10Be ◽  
Topographic Forcing ◽  
Eastern Edge

Abstract. What is the influence of glacial processes in driving erosion and uplift across the European Alps? It has largely been argued that repeated erosion through glaciation sustains isostatic uplift and topography in a decaying orogen. But, some insist that the Alps are an orogen still actively uplifting (e.g., Hergarten et al., 2010). We add insight to this debate by isolating the role of post-glacial topographic forcing on erosion rates. To do this, we quantify the topographic signature of past glaciation on millennial scale erosion rates in previously glaciated and unglaciated catchments at the easternmost edge of the Austrian Alps. Newly measured catchment-wide erosion rates, determined from cosmogenic 10Be in river-borne quartz, correlate with basin relief and mean slope. GIS-derived slope-elevation and slope-area distributions across catchments provide clear topographic indicators of the degree of glacial preconditioning, which further correlates with erosion rates. Erosion rates in the eastern-most, non-glaciated basins range from 40 to 150 mm/ky and likely reflect underlying tectonic forcings in this region, which have previously been attributed to recent (post 5 Ma) uplift (Legrain et al., 2015). By contrast, erosion rates in previously glaciated catchments range from 170 to 240 mm/ky and reflect the erosional response to local topographic preconditioning by repeated glaciations. Together, these data suggest that Holocene erosion across the Eastern Alps is strongly shaped by the local topography relict from previous glaciations. Broader, landscape-wide forcings, such as the widely debated deep mantle-driven or isostatically-driven uplift, result in lesser controls on both topography and erosion rates in this region. Comparing our data to previously published erosion rates across the Alps, we show that post-glacial erosion rates vary across more than two orders of magnitude with poor topographic indicators of controls. This high variation in post-glacial erosion may reflect combined effects of direct tectonic and modern climatic forcings, but is strongly overprinted by past glacial climate and its topographic legacy.

scholarly journals Glacial Erosion Rates Determined at Vorab Glacier: Implications for the Evolution of Limestone Plateaus

Geosciences ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 356
Author(s):  
Olivia Steinemann ◽  
Alicia Martinez ◽  
Vincenzo Picotti ◽  
Christof Vockenhuber ◽  
Susan Ivy-Ochs
Keyword(s):  
Eastern Alps ◽  
Crystalline Rock ◽  
High Elevation ◽  
Glacial Erosion ◽  
Mountain Ranges ◽  
Glacier Forefield ◽  
Erosion Rates ◽  
Cosmogenic Nuclide ◽  
Crystalline Bedrock ◽  
The Relationship

Understanding how fast glaciers erode their bedrock substrate is one of the key elements in reconstructing how the action of glaciers gives mountain ranges their shape. By combining cosmogenic nuclide concentrations determined in glacially abraded bedrock with a numerical model, we quantify glacial erosion rates over the last 15 ka. We measured cosmogenic 36Cl in fourteen samples from the limestone forefield of the Vorab glacier (Eastern Alps, Switzerland). Determined glacial erosion rates range from 0.01 mm a−1 to 0.16 mm a−1. These glacial abrasion rates differ quite markedly from rates measured on crystalline bedrock (>1 mm a−1), but are similarly low to the rates determined on the only examined limestone plateau so far, the Tsanfleuron glacier forefield. Our data, congruent with field observations, suggest that the Vorab glacier planed off crystalline rock (Permian Verrucano) overlying the Glarus thrust. Upon reaching the underlying strongly karstified limestone the glacier virtually stopped eroding its bed. We attribute this to immediate drainage of meltwater into the karst passages below the glacier, which inhibits sliding. The determined glacial erosion rates underscore the relationship between geology and the resulting landscape that evolves, whether high elevation plateaus in limestone terrains or steep-walled valleys in granitic/gneissic areas.

scholarly journals Glaciation, erosion and the evolution of the Transantarctic Mountains, Antarctica

1996 ◽  
Vol 23 ◽  
pp. 303-308 ◽  
Author(s):  
Andrew Kerr ◽  
Alan Gilchrist
Keyword(s):  
Tectonic Evolution ◽  
Flexural Rigidity ◽  
High Amplitude ◽  
Insufficient Data ◽  
Glacial Erosion ◽  
Denudation Rates ◽  
Modelling Studies ◽  
Glacial Processes ◽  
Transantarctic Mountains

Modelling studies of the tectonic evolution of the Transantarctic Mountains in Antarctica have drawn differing conclusions as to the primary mechanisms involved. None has considered the role of the East Antarctic ice sheet in detail. We use a denudation—flexural model to examine the isostatic response of the continental margin to glacial erosion to determine whether glacial processes have played a role in forcing mountain uplift. The conclusion is that, although there are insufficient data formally to delimit the role of glacial erosion, available geophysical and geomorphological data are not inconsistent with the results of the differential denudation model, providing certain conditions are met. These results indicate that the current topography of the Transantarctic Mountains can be simulated, in part, from the isostatic response of the lithosphere to glacial erosion. The short wavelength and high amplitude of the Transantarctic Mountains do not require a low flexural rigidity in the unrated lithosphere, provided there is a fast escarpment retreat from the rift hinge, high escarpment denudation rates and a large differential in denudation between the coastal zone and the interior.

scholarly journals Investigating cold based summit glaciers through direct access to the glacier base: a case study constraining the maximum age of Chli Titlis glacier, Switzerland

2018 ◽  
Vol 12 (1) ◽  
pp. 401-412 ◽  
Author(s):  
Pascal Bohleber ◽  
Helene Hoffmann ◽  
Johanna Kerch ◽  
Leo Sold ◽  
Andrea Fischer
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Eastern Alps ◽  
Systematic Investigation ◽  
Direct Access ◽  
European Alps ◽  
Central Switzerland ◽  
Ice Conditions ◽  
The Alps

Abstract. Cold glaciers at the highest locations of the European Alps have been investigated by drilling ice cores to retrieve their stratigraphic climate records. Findings like the Oetztal ice man have demonstrated that small ice bodies at summit locations of comparatively lower altitudes may also contain old ice if locally frozen to the underlying bedrock. In this case, constraining the maximum age of their lowermost ice part may help to identify past periods with minimum ice extent in the Alps. However, with recent warming and consequent glacier mass loss, these sites may not preserve their unique climate information for much longer. Here we utilized an existing ice cave at Chli Titlis (3030 m), central Switzerland, to perform a case study for investigating the maximum age of cold-based summit glaciers in the Alps. The cave offers direct access to the glacier stratigraphy without the logistical effort required in ice core drilling. In addition, a pioneering exploration had already demonstrated stagnant cold ice conditions at Chli Titlis, albeit more than 25 years ago. Our englacial temperature measurements and the analysis of the isotopic and physical properties of ice blocks sampled at three locations within the ice cave show that cold ice still exists fairly unchanged today. State-of-the-art micro-radiocarbon analysis constrains the maximum age of the ice at Chli Titlis to about 5000 years before present. By this means, the approach presented here will contribute to a future systematic investigation of cold-based summit glaciers, also in the Eastern Alps.

Glacial and periglacial buzzsaws: fitting mechanisms to metaphors

2014 ◽  
Vol 81 (2) ◽  
pp. 189-192 ◽  
Author(s):  
Adrian M. Hall ◽  
Johan Kleman
Keyword(s):  
Rock Type ◽  
Causal Link ◽  
Equilibrium Line ◽  
Glacial Erosion ◽  
Ice Flow ◽  
Passive Margins ◽  
Erosion Rates ◽  
Uplift Rates ◽  
Topographic Forcing ◽  
Innate Tendency

AbstractThe buzzsaw hypothesis refers to the potential for glacial and periglacial processes to rapidly denude mountains at and above glacier Equilibrium Line Altitudes (ELAs), irrespective of uplift rates, rock type or pre-existing topography. Here the appropriateness of the buzzsaw metaphor is examined alongside questions of the links between glacial erosion and ELAs, and whether the glacial system can produce low-relief surfaces or limit summit heights. Plateau fragments in mountains on both active orogens and passive margins that have been cited as products of glacial and periglacial buzzsaw erosion instead generally represent dissected remnants of largely inherited, pre-glacial relief. Summit heights may correlate with ELAs but no causal link need be implied as summit erosion rates are low, cirque headwalls may not directly abut summits and on passive margins, cirques are cut into pre-existing mountain topography. Any simple links between ELAs and glacial erosion break down on passive margins due to topographic forcing of ice-sheet growth, and to the km-scale vertical swaths through which ELAs have shifted through the Quaternary. Glaciers destroy rather than create low-relief rock surfaces through the innate tendency for ice flow to be faster, thicker and warmer along valleys. The glacial buzzsaw cuts down.

scholarly journals Seismic control of large prehistoric rockslides in the Eastern Alps

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Patrick Oswald ◽  
Michael Strasser ◽  
Christa Hammerl ◽  
Jasper Moernaut
Keyword(s):  
Eastern Alps ◽  
European Alps ◽  
Rock Slopes ◽  
Seismic Control ◽  
Temporal Cluster ◽  
Multiple Datasets ◽  
Moderate Seismicity ◽  
Spatio Temporal ◽  
Epicentral Intensity

AbstractLarge prehistoric rockslides tend to occur within spatio-temporal clusters suggesting a common trigger such as earthquake shaking or enhanced wet periods. Yet, trigger assessment remains equivocal due to the lack of conclusive observational evidence. Here, we use high-resolution lacustrine paleoseismology to evaluate the relation between past seismicity and a spatio-temporal cluster of large prehistoric rockslides in the Eastern Alps. Temporal and spatial coincidence of paleoseismic evidence with multiple rockslides at ~4.1 and ~3.0 ka BP reveals that severe earthquakes (local magnitude ML5.5–6.5; epicentral intensity I0VIII¼–X¾) have triggered these rockslides. A series of preceding severe earthquakes is likely to have progressively weakened these rock slopes towards critical state. These findings elucidate the role of seismicity in preparing and triggering large prehistoric rockslides in the European Alps, where rockslides and earthquakes typically occur in clusters. Such integration of multiple datasets in other formerly glaciated regions with low to moderate seismicity will improve our understanding of catastrophic rockslide drivers.

scholarly journals First Documentation of Life Cycle Completion of the Alien Rust Pathogen Melampsoridium hiratsukanum in the Eastern Alps Proves Its Successful Establishment in This Mountain Range

2021 ◽  
Vol 7 (8) ◽  
pp. 617
Author(s):  
Salvatore Moricca ◽  
Alessandra Benigno ◽  
Claudia Maria Oliveira Longa ◽  
Santa Olga Cacciola ◽  
Giorgio Maresi
Keyword(s):  
Life Cycle ◽  
Rust Fungus ◽  
Eastern Alps ◽  
Mountain Range ◽  
Field Surveys ◽  
Bank Protection ◽  
Successful Establishment ◽  
The Alps ◽  
Sem Analyses

Melampsoridium hiratsukanum is an alien rust fungus which has spread pervasively throughout several European countries following introduction into North Europe at the end of the 20th century. The authenticity of several records of the Melampsoridium species infecting alder (Alnus spp.) in the northern hemisphere is questionable, due to the misidentification and confusion that surround many of the older reports. Given this complicated taxonomic history, and since a M. hiratsukanum-like rust is strongly impacting Alnus incana stands in the Alps, probably affecting the bank protection role of this species along rivers, the unambiguous identification of this pathogen was a pressing epidemiological and ecological issue. In this study, field surveys, light (LM) and scanning electron microscopy (SEM), and molecular characterization were put together in an attempt to solve the conundrum. Field monitoring data, LM and SEM analyses of key taxonomic traits (length of ostiolar cells of uredinium, uredinio-spore shape and size, spore echinulation, number and position of germ pores) and ITS-rDNA sequence-based identification, convergently and unambiguously connected the rust that is causing the current epidemic to the non-native M. hiratsukanum. We documented the completion of the M. hiratsukanum life cycle on its two taxonomically unrelated broadleaf/conifer hosts. This is the first report of M. hiratsukanum from naturally infected Larix decidua in Europe.

scholarly journals Glaciation, erosion and the evolution of the Transantarctic Mountains, Antarctica

1996 ◽  
Vol 23 ◽  
pp. 303-308 ◽  
Author(s):  
Andrew Kerr ◽  
Alan Gilchrist
Keyword(s):  
Tectonic Evolution ◽  
Flexural Rigidity ◽  
High Amplitude ◽  
Insufficient Data ◽  
Glacial Erosion ◽  
Denudation Rates ◽  
Modelling Studies ◽  
Glacial Processes ◽  
Transantarctic Mountains

Modelling studies of the tectonic evolution of the Transantarctic Mountains in Antarctica have drawn differing conclusions as to the primary mechanisms involved. None has considered the role of the East Antarctic ice sheet in detail. We use a denudation—flexural model to examine the isostatic response of the continental margin to glacial erosion to determine whether glacial processes have played a role in forcing mountain uplift.The conclusion is that, although there are insufficient data formally to delimit the role of glacial erosion, available geophysical and geomorphological data are not inconsistent with the results of the differential denudation model, providing certain conditions are met. These results indicate that the current topography of the Transantarctic Mountains can be simulated, in part, from the isostatic response of the lithosphere to glacial erosion. The short wavelength and high amplitude of the Transantarctic Mountains do not require a low flexural rigidity in the unrated lithosphere, provided there is a fast escarpment retreat from the rift hinge, high escarpment denudation rates and a large differential in denudation between the coastal zone and the interior.

scholarly journals Alpine Rockwall Erosion Patterns Follow Elevation-Dependent Climate Trajectories

2021 ◽  
Author(s):  
Daniel Draebing ◽  
Till Mayer ◽  
Benjamin Jacobs ◽  
Samuel McColl
Keyword(s):  
Climate Change ◽  
Climate Warming ◽  
Landscape Scale ◽  
Tectonic Uplift ◽  
Future Climate ◽  
European Alps ◽  
Field Observations ◽  
Erosion Rates ◽  
Crustal Strength ◽  
The Alps

Abstract Mountainous topography reflects an interplay between tectonic uplift, crustal strength, and climate-conditioned erosion cycles. During glaciations, glacial erosion increases bedrock relief, whereas during interglacials relief is lowered by rockwall erosion. In the first landscape-scale, multi-process investigation of postglacial rockwall erosion patterns, we show that paraglacial, frost cracking and permafrost processes jointly drive rockwall erosion. Field observations and modelling experiments demonstrate that all three processes are strongly conditioned by elevation. Our findings provide a multi-process explanation for the increase of rockwall erosion rates with elevation across the European Alps. As alpine basins warm during deglaciation, changing intensities and elevation-dependent interactions between periglacial and paraglacial processes result in elevational shifts in rockwall erosion patterns. Future climate warming will shift the intensity and elevation distribution of these processes, resulting in overall lower erosion rates across the Alps, but with more intensified erosion at the highest topography most sensitive to climate change.

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