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Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides

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A special issue of Geosciences (ISSN 2076-3263).

Deadline for manuscript submissions: closed (31 January 2022) | Viewed by 36977

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Special Issue Editors

PD Dr. Naki Akçar

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Guest Editor

Institute of Geological Sciences, University of Bern, Bern, Switzerland
Interests: interaction between the geosphere, climate and human societies during the Quaternary; Quaternary geology; glacial geology; geomorphology; cosmogenic nuclides; natural hazards; paleoclimate; terrestrial Arctic; Antarctica

Prof. Dr. Susan Ivy-Ochs

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Guest Editor

Laboratory of Ion Beam Physics and Department Earth Sciences, ETH Zurich, 8093 Zurich, Switzerland
Interests: geomorphology; Quaternary geology of the Alps; cosmogenic nuclides; glacial geology; landslide geomorphology; periglacial geomorphology; geochronology; paleoclimatology

Prof. Dr. Fritz Schlunegger

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Guest Editor

Institute of Geological Sciences, University of Bern, Bern, Switzerland
Interests: geomorphology; sedimentology; surface erosion; cosmogenic nuclides for measuring denudation rates and for sediment provenance analyses

Special Issue Information

Dear Colleagues,

Over the past three decades, a better understanding of the physical processes responsible for the production of cosmogenic nuclides, as well as improvements in sampling, analytical sample preparation, and analytical techniques, have significantly increased the reliability of the cosmogenic nuclide technique and accelerated the wide applicability of cosmogenic nuclides to solve geological problems in Earth Sciences. Today, cosmogenic nuclides are an amazingly versatile tool for the dating of landforms and deposits, and for deciphering landscape evolution processes during the Quaternary. Cosmogenic nuclides have been widely applied in the dating of Quaternary ice volume fluctuations, and volcanic and palaeoseismic events as well as in quantifying surface and/or rock uplift and denudation rates. Moreover, due to the sensitivity of cosmogenic nuclide accumulation to surface erosion and depth below the surface, the application of the technique has led to significant breakthroughs in establishing terrace chronologies, and the rates and styles of local and large-scale erosion, soil development, and landscape evolution. This Special Issue, dedicated to three decades of cosmogenic nuclide research in the Earth Sciences, invites novel applications of cosmogenic nuclides (³He, ¹⁰Be, ¹⁴C, ²¹Ne, ²⁶Al, and ³⁶Cl including the new and less frequently used nuclides like ³⁸Ar and ⁵³Mn) in diverse disciplines in the Earth Sciences, as well as contributions from purely methodological and measurement arenas (AMS and noble gas mass spectrometry).

PD Dr. Naki Akçar
Prof. Dr. Susan Ivy-Ochs
Prof. Dr. Fritz Schlunegger
Guest Editors

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Keywords

Quaternary
Landscape evolution
Cosmogenic nuclide
Surface exposure dating
Burial dating
Isochron-burial dating
Depth-profile dating
Erosion rates
Accelerator mass spectrometry
Geochronology
Neotectonic
Denudation rates

Published Papers (13 papers)

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Editorial

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5 pages, 236 KiB

Open AccessEditorial

A Special Issue of Geosciences: Cutting Edge Earth Sciences—Three Decades of Cosmogenic Nuclides

by Naki Akçar, Susan Ivy-Ochs and Fritz Schlunegger

Geosciences 2022, 12(11), 409; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences12110409 - 05 Nov 2022

Viewed by 1115

Abstract

What we know is a drop, what we don’t know is an ocean [...] Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

Research

Jump to: Editorial

22 pages, 15777 KiB

Open AccessArticle

LGM Glaciations in the Northeastern Anatolian Mountains: New Insights

by Regina Reber, Naki Akçar, Dmitry Tikhomirov, Serdar Yesilyurt, Christof Vockenhuber, Vural Yavuz, Susan Ivy-Ochs and Christian Schlüchter

Geosciences 2022, 12(7), 257; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences12070257 - 22 Jun 2022

Cited by 6 | Viewed by 1899

Abstract

Barhal Valley belongs to the Çoruh Valley System in the Kaçkar Mountains of northeastern Anatolia. This 13 km long valley is located to the south of the main weather divide and to the east of Mt. Kaçkar, with the highest peak of the mountain range being 3932 m. Today, source of an average yearly precipitation of 2000 mm of moisture is the Black Sea, situated approximately 40 km to the north of the study site. Glaciers of the Last Glacial Maximum (LGM) descended directly from Mt. Kaçkar and reached an altitude of ca. 1850 m a.s.l. (above sea level). In this study, we are exploring whether the position of Barhal Valley to the south of the main weather divide and its east–west orientation have an influence on the existence and expansion of paleoglaciers. Here, we present 32 new cosmogenic ³⁶Cl dates on erratic boulders from the Çoruh Valley System. We reconstructed three geomorphologically well-contained glacier advances in the Barhal Valley, namely at 34.0 ± 2.3 ka, 22.2 ± 2.6 ka, and 18.3 ± 1.7 ka within the time window of the global LGM. Field evidence shows that the glacier of the 18.3 ± 1.7 ka advance disappeared rapidly and that by the latest time, at 15.6 ± 1.8 ka, the upper cirques were ice-free. No evidence for Lateglacial glacier fluctuations was found, and the Neoglacial activity is restricted to the cirques with rock glaciers. A range of 2700 to 3000 m for the Equilibrium Line Altitude (ELA) at the LGM was reported based on modeling of the glacial morphology. We determined that the most likely position of the LGM ELA in the Çoruh Valley System was at 2900 m a.s.l. We suggest an alternative moisture source to the direct transport from the Black Sea for the ice accumulation in the Eastern Black See Mountains. The shift of the Polar Front and of the Siberian High Pressure System to the south during the LGM resulted in the domination of easterly airflow to the Caucasus and Kaçkar Mountains with moisture from expanded lakes in central–western Siberia and from the enlarged Aral- and Caspian Seas. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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42 pages, 12124 KiB

Open AccessArticle

Soil Formation and Mass Redistribution during the Holocene Using Meteoric ¹⁰Be, Soil Chemistry and Mineralogy

by Alessandra Musso, Dmitry Tikhomirov, Michael L. Plötze, Konrad Greinwald, Anne Hartmann, Clemens Geitner, Fabian Maier, Fanny Petibon and Markus Egli

Geosciences 2022, 12(2), 99; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences12020099 - 21 Feb 2022

Cited by 8 | Viewed by 3816

Abstract

Soil development and erosion are important and opposing processes in the evolution of high-mountainous landscapes, though their dynamics are not fully understood. We compared soil development between a calcareous and a siliceous chronosequence in the central Swiss Alps at high altitudes, which both cover soil formation over the Holocene. We calculated element mass balances, long-term erosion rates based on meteoric ¹⁰Be and we determined the rates of soil formation. We also analyzed the shifts in the mineralogical composition, weathering indices, the particle size distribution, carbon stocks and oxalate extractable Fe, Al, and Mn. The siliceous soils had high chemical weathering rates at the early stage of soil formation that strongly decreased after a few millennia. The development of calcareous soil was characterized by high carbonate losses and a shift to finer soil texture. Soil erosion hampered the upbuilding of soil horizons in the early stages of soil development, which led to a delay in soil and vegetation development. This study shows how soil formation drivers change over time. In the early stages of soil development, the parent material predominantly drives soil formation while at later stages the vegetation becomes more dominant as it influences surface stability, hydrological pathways, and chemical weathering that determine water drainage and retention. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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20 pages, 13908 KiB

Open AccessArticle

Age of the Most Extensive Glaciation in the Alps

by Catharina Dieleman, Marcus Christl, Christof Vockenhuber, Philip Gautschi, Hans Rudolf Graf and Naki Akçar

Geosciences 2022, 12(1), 39; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences12010039 - 13 Jan 2022

Cited by 8 | Viewed by 3311

Abstract

Previous research suggested that the Alpine glaciers of the Northern Swiss Foreland reached their maximum extensive position during the Middle Pleistocene. Relict tills and glaciofluvial deposits, attributed to the Most Extensive Glaciation (MEG), have been found only beyond the extents of the Last Glacial Maximum (LGM). Traditionally, these sediments have been correlated to the Riss glaciation sensu Penck and Brückner and have been morphostratigraphically classified as the Higher Terrace (HT) deposits. The age of the MEG glaciation was originally proposed to be intermediate to the Brunhes/Matuyama transition (780 ka) and the Marine Isotope Stage 6 (191 ka). In this study, we focused on the glacial deposits in Möhlin (Canton of Aargau, Switzerland), in order to constrain the age of the MEG. The sediments from these deposits were analyzed to determine the provenance and depositional environments. We applied isochron-burial dating, with cosmogenic ¹⁰Be and ²⁶Al, to the till layer in the Bünten gravel pit near Möhlin. Our results indicate that a glacier of Alpine origin reached its most extensive position during the Middle Pleistocene (500 ± 100 ka). The age of the MEG thus appears to be synchronous with the most extensive glaciations in the northern hemisphere. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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23 pages, 12154 KiB

Open AccessArticle

Seismic Activity of the Manisa Fault Zone in Western Turkey Constrained by Cosmogenic ³⁶Cl Dating

by Nasim Mozafari, Çağlar Özkaymak, Dmitry Tikhomirov, Susan Ivy-Ochs, Vasily Alfimov, Hasan Sözbilir, Christian Schlüchter and Naki Akçar

Geosciences 2021, 11(11), 451; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences11110451 - 31 Oct 2021

Cited by 5 | Viewed by 2843

Abstract

This study reports on the cosmogenic ³⁶Cl dating of two normal fault scarps in western Turkey, that of the Manastır and Mugırtepe faults, beyond existing historical records. These faults are elements of the western Manisa Fault Zone (MFZ) in the seismically active Gediz Graben. Our modeling revealed that the Manastır fault underwent at least two surface ruptures at 3.5 ± 0.9 ka and 2.0 ± 0.5 ka, with vertical displacements of 3.3 ± 0.5 m and 3.6 ± 0.5 m, respectively. An event at 6.5 ± 1.6 ka with a vertical displacement of 2.7 ± 0.4 m was reconstructed on the Mugırtepe fault. We attribute these earthquakes to the recurring MFZ ruptures, when also the investigated faults slipped. We calculated average slip rates of 1.9 and 0.3 mm yr⁻¹ for the Manastır and Mugırtepe faults, respectively. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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26 pages, 6193 KiB

Open AccessArticle

Reconstructing the Gorte and Spiaz de Navesele Landslides, NE of Lake Garda, Trentino Dolomites (Italy)

by Giacomo Ruggia, Susan Ivy-Ochs, Jordan Aaron, Olivia Steinemann, Silvana Martin, Manuel Rigo, Sandro Rossato, Christof Vockenhuber, Giovanni Monegato and Alfio Viganò

Geosciences 2021, 11(10), 404; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences11100404 - 25 Sep 2021

Cited by 3 | Viewed by 2810

Abstract

We applied a multi-method approach to reconstruct the Gorte rock avalanche (85–95 Mm³) located at the northeastern end of Lake Garda. The combination of field mapping, characterization of bedrock discontinuities, Dan3D-Flex runout modeling and dating of boulders with cosmogenic ³⁶Cl supports the conclusion that the deposits stem from a single rock avalanche at 6.1 ± 0.8 ka. The Gorte event may have triggered the Spiaz de Navesele–Salto della Capra landslide (3.2 Mm³), whose deposits cover the southern end of the Gorte deposits. First-order controls on detachment were the NNE–SSW- and WNW–ESE-oriented fractures in the limestone bedrock, related to the Giudicarie and Schio-Vicenza fault systems, respectively. Dan3D-Flex runout modeling sufficiently reproduced the Gorte rock avalanche, which involved detachment and sliding of a quasi-intact block, likely along marly interbeds, followed by rapid disintegration. The frictional rheology in the source area and the turbulent frictional rheology (Voellmy) in the remaining part best replicate the observed deposit extent and thickness. Heavy precipitation that occurred at that time may have contributed to failure at Gorte. Nonetheless, its timing overlaps with the nearby (<15 km) Dosso Gardene (6630–6290 cal BP) and Marocca Principale (5.3 ± 0.9 ka) landslides, making a seismic trigger plausible. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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15 pages, 2915 KiB

Open AccessArticle

Empirical Evidence for Latitude and Altitude Variation of the In Situ Cosmogenic ²⁶Al/¹⁰Be Production Ratio

by Christopher T. Halsted, Paul R. Bierman and Greg Balco

Geosciences 2021, 11(10), 402; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences11100402 - 23 Sep 2021

Cited by 10 | Viewed by 2275

Abstract

We assess if variations in the in situ cosmogenic ²⁶Al/¹⁰Be production ratio expected from nuclear physics are consistent with empirical data, knowledge critical for two-isotope studies. We do this using 313 samples from glacially transported boulders or scoured bedrock with presumed simple exposure histories in the Informal Cosmogenic-nuclide Exposure-age Database (ICE-D) from latitudes between 53°S to 70°N and altitudes up to 5000 m above sea level. Although there were small systematic differences in Al/Be ratios measured in different laboratories, these were not significant and are in part explained by differences in elevation distribution of samples analyzed by each laboratory. We observe a negative correlation between the ²⁶Al/¹⁰Be production ratio and elevation (p = 0.0005), consistent with predictions based on the measured energy dependence of nuclear reaction cross-sections and the spatial variability in cosmic-ray energy spectra. We detect an increase in the production ratio with increasing latitude, but this correlation is significant only in a single variate model, and we attribute at least some of the correlation to sample elevation bias because lower latitude samples are typically from higher elevations (and vice versa). Using 6.75 as the ²⁶Al/¹⁰Be production ratio globally will bias two-isotope results at higher elevations and perhaps higher latitudes. Data reported here support using production rate scaling that incorporates such ratio changes, such as the LSDn scheme, to minimize such biases. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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18 pages, 36624 KiB

Open AccessArticle

Cosmogenic Exposure Dating (³⁶Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on ³⁶Cl Ages

by Johanna Anjar, Naki Akҫar, Eiliv A. Larsen, Astrid Lyså, Shasta Marrero, Nasim Mozafari and Christof Vockenhuber

Geosciences 2021, 11(9), 390; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences11090390 - 15 Sep 2021

Cited by 5 | Viewed by 2980

Abstract

Jan Mayen is a small volcanic island situated 550 km north of Iceland. Glacial sediments and landforms are relatively common on the island but, so far, only a few of them have been dated. In this study, we present and discuss 89 ³⁶Cl dates of primarily glacial and volcanic events on Jan Mayen. Calculations of sample exposure ages were complicated by young exposure ages, young rock formation age, and high native Cl contents, leading to updates in CRONUScalc to enable accurate exposure age calculations. The samples provide good evidence against an equilibrium assumption when subtracting background production (e.g., ³⁶Cl produced by neutron capture from fission of U or Th) for samples on young bedrock, with younger exposure ages most significantly affected. Exposure ages were calculated with a range of assumptions of bedrock formation ages appropriate for Jan Mayen, including the assumption that the rock formation age equaled the exposure age (i.e., the youngest age it could possibly have), and we found that although the effect on most of the ages was small, the calculated ages of 25 of the samples increased by more than 1 standard deviation from the age calculated assuming equilibrium background production, with a maximum deviation of 6.1 ka. Due to the very young bedrock on Jan Mayen, we consider the nonequilibrium ages to be the most reliable ages from the island and conclude that large-scale deglaciation on the south and central, lower-lying, parts of the island, started around 20 ka and lasted until ~7 ka. On northern Jan Mayen, the slopes of the 2277 m high stratovolcano Beerenberg are currently partly glaciated; however, outside of the Little Ice Age moraines, all but two samples give ages between 14 and 5.7 ka. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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13 pages, 2665 KiB

Open AccessArticle

The NUNAtak Ice Thinning (NUNAIT) Calculator for Cosmonuclide Elevation Profiles

by Ángel Rodés

Geosciences 2021, 11(9), 362; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences11090362 - 26 Aug 2021

Cited by 3 | Viewed by 2016

Abstract

Cosmogenic nuclides are widely used to constrain the landscape history of glaciated areas. At nunataks in continental polar regions with extremely arid conditions, cosmogenic nuclides are often the only method available to date the ice thinning history of the glacier. However, the amount of cosmogenic isotopes accumulated at the surface of nunataks depends not only on the length of time that rock has been exposed since the last deglaciation but also on the full history of the surface, including muon production under ice, exposure during previous interglacials, subaerial weathering rate, glacial erosion rate, and uplift rate of the nunatak. The NUNAtak Ice Thinning model (NUNAIT) simulates the cosmonuclide accumulation on vertical profiles, fitting the aforementioned parameters to a set of multi-isotope apparent ages from samples taken at different elevations over the ice-sheet surface. The NUNAIT calculator is an easy-to-use tool that constrains parameters that describe the geological history of a nunatak from a set of surface exposure ages. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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21 pages, 13559 KiB

Open AccessArticle

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

by Olivia Steinemann, Alicia Martinez, Vincenzo Picotti, Christof Vockenhuber and Susan Ivy-Ochs

Geosciences 2021, 11(9), 356; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences11090356 - 24 Aug 2021

Cited by 1 | Viewed by 2641

Abstract

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. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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14 pages, 2605 KiB

Open AccessArticle

New System for Measuring Cosmogenic Ne in Terrestrial and Extra-Terrestrial Rocks

by Domokos Györe, Luigia Di Nicola, David Currie and Finlay M. Stuart

Geosciences 2021, 11(8), 353; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences11080353 - 23 Aug 2021

Cited by 4 | Viewed by 2734

Abstract

Cosmogenic Ne isotopes are used for constraining the timing and rate of cosmological and Earth surface processes. We combined an automated gas extraction (laser) and purification system with a Thermo Fisher ARGUS VI mass spectrometer for high through-put, high precision Ne isotope analysis. For extra-terrestrial material with high cosmogenic Ne concentrations, we used multi-collection on Faraday detectors. Multiple measurements (n = 26) of 1.67 × 10⁻⁸ cm³ air-derived ²⁰Ne yielded an uncertainty of 0.32%, and ²¹Ne/²⁰Ne = 0.17% and ²²Ne/²⁰Ne = 0.09%. We reproduced the isotope composition of cosmogenic Ne in the Bruderheim chondrite and Imilac pallasite in a sub-ten mg sample. For lower Ne amounts that are typical of terrestrial samples, an electron multiplier detector was used in peak jumping mode. Repeated analysis of 3.2 × 10⁻¹¹ cm³ STP ²⁰Ne from air reproduced ²¹Ne/²⁰Ne and ²²Ne/²⁰Ne with 1.1% and 0.58%, respectively, and ²⁰Ne intensity with 1.7% (n = 103) over a 4-month period. Multiple (n = 8) analysis of cosmogenic Ne in CREU-1 quartz yielded 3.25 ± 0.24 × 10⁸ atoms/g (2 s), which overlaps with the global mean value. The repeatability is comparable to the best data reported in the international experiments performed so far on samples that are 2–5× smaller. The ability to make precise Ne isotope determinations in terrestrial and extra-terrestrial samples that are significantly smaller than previously analysed suggests that the new system holds great promise for studies with limited material. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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28 pages, 9151 KiB

Open AccessArticle

Cosmogenic and Geological Evidence for the Occurrence of a Ma-Long Feedback between Uplift and Denudation, Chur Region, Swiss Alps

by Ewerton da Silva Guimarães, Romain Delunel, Fritz Schlunegger, Naki Akçar, Laura Stutenbecker and Marcus Christl

Geosciences 2021, 11(8), 339; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences11080339 - 12 Aug 2021

Cited by 2 | Viewed by 2352

Abstract

We used concentrations of in situ cosmogenic ¹⁰Be from riverine sediment to quantify the basin-averaged denudation rates and sediment fluxes in the Plessur Basin, Eastern Swiss Alps, which is a tributary stream to the Alpine Rhine, one of the largest streams in Europe. We complement the cosmogenic dataset with the results of morphometric analyses, geomorphic mapping, and sediment fingerprinting techniques. The results reveal that the Plessur Basin is still adjusting to the landscape perturbation caused by the glacial carving during the Last Glacial Maximum c. 20,000 years ago. This adjustment has been most efficient in the downstream part where the bedrock comprises high erodibility North Penninic flysch and Bündnerschist, whereas glacial landforms are still prominently preserved in the upstream region, comprising low erodibility South Penninic and Austroalpine bedrock. This geomorphic observation is supported by the ¹⁰Be based denudation rate and sediment provenance analysis, which indicate a much faster sediment production in the flysch and schist lithologies. Interestingly, the reach of fast denudation has experienced the highest exhumation and rock uplift rates. This suggests that lithologic and glacial conditioning have substantially contributed to the local uplift and denudation as some of the driving forces of a positive feedback system. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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20 pages, 36396 KiB

Open AccessArticle

Slope Failure in a Period of Increased Landslide Activity: Sennwald Rock Avalanche, Switzerland

by Selçuk Aksay, Susan Ivy-Ochs, Kristina Hippe, Lorenz Grämiger and Christof Vockenhuber

Geosciences 2021, 11(8), 331; https://0-doi-org.brum.beds.ac.uk/10.3390/geosciences11080331 - 05 Aug 2021

Cited by 2 | Viewed by 3397

Abstract

The Säntis nappe is a complex fold-and-thrust structure in eastern Switzerland, consisting of numerous tectonic discontinuities and a range of hillslopes prone to landsliding and large slope failures that modify the topography irreversibly. A slope failure, namely the Sennwald rock avalanche, occurred in the southeast wall of this fold-and-thrust structure due to the rock failure of Lower Cretaceous Helvetic limestones along the Rhine River valley. In this research, this palaeolandslide is examined in a multidisciplinary approach for the first time with detection and mapping of avalanche deposits, dynamic run-out modelling and cosmogenic nuclide dating. During the rock failure, the avalanche deposits were transported down the hillslope in a spreading-deck fashion, roughly preserving the original stratigraphic sequence. The distribution of landslide deposits and surface exposure age of the rock failure support the hypothesis that the landslide was a single catastrophic event. The ³⁶Cl surface exposure age of avalanche deposits indicates an age of 4.3 ± 0.5 ka. This time coincides with a notably wet climate period, noted as a conditioning factor for landslides across the Alps in the mid-Holocene. The contemporaneity of our event at its location in the Eastern Alps provide additional support for the contention of increased regional seismic activity in mid-Holocene. Full article

(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)

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