Orals: Tue, 29 Apr | Room -2.21
At the end of the last glaciation, landscapes have undergone profound changes, with increased temperature and modification of precipitation regimes changing the way sediments are produced and transported at the Earth's surface. Records of past denudation rates are essential for understanding how landscapes responded to this transition, and to assess their sensitivity to local environmental, climatic and geomorphic conditions. Terrestrial Cosmogenic Nuclides (TCN) can be used in different ways to constrain paleo-denudation rates over 10s ka timescales, but few datasets exist that display strong signals regarding the dependency of this response to local setting characteristics, and the diversity of the approaches limits the possibilities for a global analysis.
We propose a new approach to constrain changes in erosion rates over the Pleistocene-Holocene transition, using the well-known concept that erosion rates derived from concentrations average over a timescale inversely proportional to the erosion rate. By combining TCN data with topographic information, we constrain the amplitude of erosion changes across neighboring basins that are eroding at different rates. We highlight a complex pattern, with an overall pronounced several-fold increase in denudation rate when entering the Holocene. Intertropical high-relief settings appear to be more likely to displaying an increase in denudation rates, which might reflect a stronger sensitivity of these landscapes to periglacial processes, monsoon regime or threshold hillslope dynamics.
How to cite: Godard, V., Mudd, S., and Attal, M.: Global Pleistocene-Holocene variations in denudation rates constrained from a joint analysis of cosmogenic nuclides and morphological data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6340, https://doi.org/10.5194/egusphere-egu25-6340, 2025.
Bioturbation has a large impact of carbon and nutrient cycling in soils and therefore plays a key role in current-day soil functioning and long-term soil evolution. Despite its importance, fundamental knowledge on the mechanisms and rates of different soil bioturbation processes is limited, which prohibits accurate modelling of these processes.
Luminescence, a light-sensitive mineral property of the two most abundant minerals at the Earth surface (quartz and feldspar), is a valuable tracer for deriving rates of long-term bioturbation. It measures the last exposure of siliclastic particles to daylight and can therefore act as a proxy of subsurface residence times. However, these luminescence tracers do not account for previous resurfacing of grains and subsurface transport without bleaching, and therefore only represent the net replacement of the particles. This leads to an underestimation of bioturbation rates when derived from luminescence tracers only.
In this presentation, we introduce the new simulation model named Mixed Signals, which simulates two main bioturbation processes and their impacts on luminescence tracers: mounding (advective transport to the surface) and subsurface mixing (diffusive transport within the subsurface). We applied the model to two published luminescence datasets, each from settings dominated by organisms with distinct burrowing behavior: termites and anecic earthworms. We calibrated the model using different statistics derived from the experimental and simulated luminescence age distributions to derive bioturbation rates and mixing characteristics for the two datasets.
The model produced bioturbation rates that are orders of magnitude larger than the rates derived from the luminescence datasets alone, yet they are consistent with rates derived from observations. While some limitations remain, such as the need for a better experimental understanding of light penetration in soils for particle bleaching, our findings show the potential of the Mixed Signals model to extract accurate bioturbation rates from luminescence data. The model greatly enhances our understanding of bioturbation dynamics and improves the use of luminescence as a tracer for soil processes.
How to cite: van der Meij, M., Riedesel, S., and Reimann, T.: Mixed Signals: soil bioturbation rates from luminescence and numerical modelling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5643, https://doi.org/10.5194/egusphere-egu25-5643, 2025.
Many mountain glaciers have experienced an increase in supraglacial debris cover due to climate change. Understanding sediment transport processes in glacier systems is important because the accumulation of supraglacial debris affects glacier evolution and response to climate change. Tracking debris and sediment transport through glacial catchments is difficult and thus, the pathway and time scale of englacially transported debris are relatively poorly understood. We quantify the englacial transport time of debris within a glacier using a novel method combining luminescence rock surface burial dating and ice-flow modelling (Margirier et al., 2025). Our study focuses on the Mer de Glace catchment, French Alps, where supraglacial debris cover has expanded over the past half-century.
We collected granitic rock debris clasts (4–22 cm in diameter) that were embedded in ice in the ablation area of Mer de Glace, which we expected to have undergone varying durations of englacial transport. The clasts were assumed to originate from headwalls (paraglacial areas), where they were exposed to daylight before falling onto the glacier and being transported englacially. Cores were extracted from the unexposed rock surfaces and sliced into ~0.9 mm thick discs for luminescence dating. We measured the luminescence signal using a single-aliquot regenerative dose protocol comprising infra-red stimulation, followed by blue stimulation to explore the signals of different minerals with different luminescence properties. Of the 29 samples investigated, 19 were well bleached prior to burial, exhibiting a clear plateau in luminescence signals with depth, and 15 samples have been successfully dated giving burial ages between 0.58 ± 0.13 ka and 6.73 ± 0.72 ka. Except for two samples that are significantly older, luminescence ages are consistent across the glacier, which suggest that the rate of sediment transport is broadly consistent across the ice. Future work will contrast the englacial burial time obtained with luminescence dating with those predicted by an ice-flow model of particle transport trajectories within the Mer de Glace. This will allow particle sources to be better identified and to understand the ice dynamics of the glacier.
Reference:
Margirier A., J. Brondex, A.V. Rowan, C. Schmidt, V.K. Pedersen, B. Lehmann, L.S. Anderson, R. Veness, C.S. Watson, D. Swift, G.E. King (2025), Tracking sediment transport through Miage Glacier, Italy, using a Lagrangian approach with luminescence rock surface burial dating of englacial clasts, JGR: Earth Surface.
How to cite: Rodari, L., Audrey, M., King, G. E., Rowan, A. V., Schmidt, C., and Jouvet, G.: Combined luminescence dating and ice-flow modelling to track Holocene sediment transport through Mer de Glace, French Alps, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11697, https://doi.org/10.5194/egusphere-egu25-11697, 2025.
Rock glaciers are common permafrost features in mountain landscapes around the globe. They pose a geo hazardous risk1 sourcing large amounts of debris while also acting as aquifers storing large amounts of water2. Due to limited dating efforts on rock glaciers, their long-term (i.e. centennial to millennial scale) dynamics and response to climate variability are poorly understood. Short term observations, via GPS, InSAR, UAVSAR, Lidar or feature tracking, show acceleration of flow rates of rock glaciers in all mountain regions3. Understanding past dynamics is key to project rock glacier behavior under future global warming.
This study combines cosmogenic radionuclide (CRN), and rock surface dating based on optically stimulated luminescence (OSL RSD) on a rock glacier in the Uinta Mountains (Utah, USA, 3300 m asl.). CRN dating of 8 quartzite boulders has been conducted by Munroe et al.4 and the same boulders were sampled for OSL RSD. 4 additional OSL samples of dark red quartzite were taken for increased dating resolution during fieldwork in 2024. The independent cosmogenic age control allows us to (i) test the applicability of OSL RSD in a high-altitude periglacial setting, (ii) investigate the sensitivity of the model parameters that are folded into the OSL bleaching-with-depth model and (iii) based on conceptual work by Sohbati et al.5 and Lehmann et al.6 to determine rock surface erosion rates of the quarzitic host lithology.
1. Schoeneich, P. et al. Velocity Changes of Rock Glaciers and Induced Hazards. In Engineering Geology for Society and Territory - Volume 1, edited by G. Lollino, A. Manconi, J. Clague, W. Shan & M. Chiarle (Springer International Publishing, Cham, 2015), pp. 223–227.
2. Jones, D. B., Harrison, S., Anderson, K. & Whalley, W. B. Rock glaciers and mountain hydrology: A review. Earth-Science Reviews 193, 66–90; 10.1016/j.earscirev.2019.04.001 (2019).
3. Pellet, C. et al. Rock Glacier Velocity. In State of the Climate in 2023, edited by J. Blunden & T. Boyer (2024), pp. 44–46.
4. Munroe, J. S., Laabs, B. J. C., Corbett, L. B., Bierman, P. R. & Handwerger, A. L. Rock Glacier Movement and Debris Transport Over Annual to Multi‐Millennial Timescales. JGR Earth Surface 129; 10.1029/2023JF007453 (2024).
5. Sohbati, R. et al. Centennial- to millennial-scale hard rock erosion rates deduced from luminescence-depth profiles. Earth and Planetary Science Letters 493, 218–230; 10.1016/j.epsl.2018.04.017 (2018).
6. Lehmann, B., Herman, F., Valla, P. G., King, G. E. & Biswas, R. H. Evaluating post-glacial bedrock erosion and surface exposure duration by coupling in situ optically stimulated luminescence and 10Be dating. Earth Surf. Dynam. 7, 633–662; 10.5194/esurf-7-633-2019 (2019).
How to cite: Sperlich, D., Meyer, M., and Munroe, J.: Combining Cosmogenic Surface-Exposure and OSL Rock Surface Dating on a rock glacier in the Uinta Mountains (USA) - a comparative methodological study on exposure ages and a novel tool to constrain host rock erosion rates, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10798, https://doi.org/10.5194/egusphere-egu25-10798, 2025.
Hillslope processes play a significant role in shaping catchment-scale erosional dynamics. These processes include mechanisms from granular creep to large-scale morphological changes influenced by tectonic and climatic forces over both short and long timescales. Despite advancements in quantification methods, a granular-level understanding of these processes remains unclear. Moreover, a systematic approach to link the variability of hillslope processes across different temporal scales is still lacking. Thus, integrating single-grain luminescence analysis with cosmogenic nuclide-derived erosion rates from modern fluvial deposits can bridge these gaps, offering deeper insights into hillslope processes.
Single-grain luminescence provides detailed grain-specific insights into sediment production, erosion, transport, and deposition processes over millennial timescales. In contrast, cosmogenic nuclide-based methods analyze the long-term mean signal from a large grain population. Thus, comparing single-grain luminescence dose distribution with cosmogenic 10Be-derived catchment-wide erosion rates in fluvial sediments could help identify various hillslope processes with higher analytical resolution over varying timescales. We hypothesized that grains transported by soil creep will be sufficiently bleached (zero or negligible remaining luminescence signal). In contrast, grains transported via landslides will predominantly exhibit incomplete or no bleaching (considerable remaining luminescence signal or saturated with luminescence signal).
To test this hypothesis, we measured the proportion of bleached versus non-bleached grains in modern fluvial deposits sourced from 11 catchments falling in a climatic gradient and also with contrasting morphometric properties in the Southern Central Andes (Chile) using post-IR IRSL signal of K-feldspar. Contrary to expectations, we observed a weak negative correlation between the proportion of bleached grains and erosion rates, suggesting complex transport dynamics and variable opportunities for bleaching across catchments. Additionally, a weak positive correlation between non-bleached grains and erosion rates suggests complex sediment storage and reworking within the system, and an absence of large morphologic changes, such as deep-seated landslides.
Therefore, comparing the luminescence signals of hundreds of grains with catchment-wide erosion rates across various temporal scales provides valuable complementary insights into (a) the mechanisms driving hillslope erosion, (b) their influence on catchment-wide erosion rate estimates, and (c) the complex sediment dynamics within catchments.
How to cite: Biswas, A., Riedesel, S., Karman-Besson, L., Guyez, A., A. Binnie, S., Bonnet, S., and Reimann, T.: Linking single-grain luminescence and erosion rates to understand erosional and sediment dynamics in the Southern Central Andes, Chile, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2881, https://doi.org/10.5194/egusphere-egu25-2881, 2025.
In recent decades, the quantification of Earth surface processes such as erosion, sediment transport, and deposition has gained increasing attention, with a focus on investigating their interplay across different spatial and temporal scales. This study contributes to address these challenges by combining in-situ cosmogenic 10Be isotopic analyses with a modified version of the Erosion Potential Model (EPM) to explore landscape and sediment dynamics in the Sfalassà stream catchment in Calabria, southern Italy.
A total of 26 samples, including river sands of two different grain sizes and rock samples, were collected to estimate long-term erosion rates, sediment residence times (average exposure ages), and rates of vertical river dissection across the catchment. The adoption of 10Be cosmogenic nuclide enables a detailed understanding of erosion and sediment transport processes on millennial timescales, providing time frames for the main processes that have shaped the basin. The Sfalassà catchment, characterized by a diverse range of lithologies, geomorphological units, vegetation cover, land uses, and anthropogenic activities, was selected as a representative pilot basin in the central Mediterranean area. Sampling was conducted across the main channel and its tributaries to ensure comprehensive coverage. Field surveys formed the core of our sampling strategy, supplemented by aerial photo interpretation, GIS and thematic mapping analyses to enhance site selection.
The EPM was upgraded using the catchment’s geological and pedological erodibility parameters. The specific weights of geological parameters and the differentiation of lithological classes assigned to various lithologies available in the literature were modified, trying to enhance the model accuracy for estimating medium-term erosion rates. This adjustment involved an integration of the spatial distribution of rock outcrops with that of major soil types, focusing on their varying susceptibility to surface erosion. Additionally, rainfall data were extrapolated at different elevations using a regression function of data from weather stations. In contrast to the EPM, the 10Be analyses provided precise and direct in situ measurements, enriching our understanding of catchment-scale erosion processes through the integration of methodologies.
Despite operating on different temporal scales, the integration of isotopic data with the EPM may enhance the model’s accuracy. This synergy may provide a more robust framework for the quantification of sediment fluxes and erosion process modeling, contributing to a deeper understanding of sediment dynamics. This interdisciplinary approach not only sheds light on the connectivity between sediment source areas and the drainage system but can also suggest practical tools for assessing and managing sediment dynamics and coastal erosion risks. Based on the rates at which river sediments feed coastal areas, it highlights conditions of balance/unbalance in the sedimentary input, thus emphasizing broader geomorphological implications.
The research is part of the "TECH4YOU – Technologies for climate change adaptation and quality of life improvement" project, funded by Next Generation EU (PNRR M4.C2.1.5). By combining geochronological techniques with numerical modeling, this study contributes to advancing methodologies for basin-scale investigations, offering replicable protocols applicable to diverse geo-environmental contexts and improving our understanding of sedimentary processes from source to sink.
How to cite: De Cesare, P., Egli, M., Tikhomirov, D., Christl, M., Imbrogno, G., and Scarciglia, F.: Integrating 10Be analyses and an empirical erosion model to unveil catchment-scale landscape and sediment dynamics, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8861, https://doi.org/10.5194/egusphere-egu25-8861, 2025.
The origin of inselbergs is classically linked to long-term episodic exposure, alternating between the deepening of the weathering mantle and the regolith stripping driven by differential erosion. However, a better understanding of denudation patterns and exposures ages in granite landscapes is hindered by key gaps arising with this assumption: i) the absence of sedimentary markers or their dating; ii) the scarcity of quantified denudation rates to reconcile with classical models of evolution in cratonic zones. To address these gaps, in-situ produced 10Be and 26Al in river-borne sediments, bedrocks, and sedimentary deposits can be compared and analyzed to quantify the role played by differential erosion in the evolution of granitic inselbergs and to unravel complex exposure histories. Previous studies quantifying erosion in granitic landscapes have focused on small inselberg groups or isolated high inselbergs, comparing rock surfaces without integrating sedimentary covers or basin-averaged denudation, thereby limiting regional-scale understanding. In this study, we paired 10Be and 26Al in quartz from sands and rocks collected across watersheds, colluvial-eluvial sediments, and inselbergs. Denudation rates were combined to reconstruct the history of inselbergs in a tropical semiarid setting.
Using this approach, we selected the Quixadá/Quixeramobim Complex (NE Brazil), a globally significant inselberg field with 561 units, renowned for its diverse granite landforms in cratonic and semiarid areas. These landforms rise 1-410 m above the Surface Sertaneja (160-240 m). Within the plutons, the erosion surface is ~20 m lower than in adjacent regions, where metamorphic rocks and colluvial-eluvial covers are found.
Our results show that colluvial-eluvial covers exhibit higher cosmogenic nuclide concentrations than bedrocks, with values at least twice as high as those in watersheds. Conversely, catchments experience faster erosion than bedrocks. All bedrocks and 60% of the catchments are plotted within the steady-state erosion island, whereas Cenozoic covers display low 26Al/10Be ratios. Average exposure ages suggest a Pleistocene age (1.0-1.4 Ma) for sedimentary covers. This reflects a general denudation pattern where inselbergs and sedimentary surfaces are preserved while the regional erosion surface is progressively stripped.
Assuming no erosion for sedimentary covers and continuous denudation, the differential denudation obtained between inselberg top and basin-averaged rates indicates that ~20 Ma is required to grow a 175 m-high inselberg, and ~50 Ma for a 400 m-high inselberg. These results highlight the utility of cosmogenic techniques in measuring denudation rates and improving the understanding of processes that govern origin and development of inselbergs.
How to cite: da Silva Barbosa, A. B., Siame, L., Maia, R. P., Leanni, L., Bastos, F. D. H., and Team, A.: Erosion and development of granitic inselbergs in cratonic zones: insights from the Quixadá/Quixeramobim Complex, NE Brazil, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5239, https://doi.org/10.5194/egusphere-egu25-5239, 2025.
Cosmogenic isotope dating of rock samples taken from shore platforms is the only dating method for reconstructing the long-term evolution (centuries to millennia) of fully erosional rock coasts. Two techniques can be used: the first is based on the collection of samples on the platform and the distribution of their cosmogenic isotope concentrations over a transect perpendicular to the shoreline (e.g. Regard et al., 2012; Hurst et al., 2016; Swirad et al., 2020); the second, which is limited to low rates of recession, is implemented by measuring cosmogenic isotope concentrations in the colluvium at the foot of the cliff (Bossis et al., 2024). Here we focus on the first technique which involves fitting the distribution of observed concentrations to a model. This model allows the cliff retreat rate to be constant or variable over the Holocene, and shore platform either to erode in concert with the cliff retreat (steady state model) or to widen through time. The simple inversion model is as widely usable as possible and allows a quick, easy, robust and standardised calculation of exposure ages based on information such as cosmogenic isotope concentrations, present topography and relative sea level change.
References
Bossis, R., Regard, V., Carretier, S., and Choy, S., 2024, Evidence of slow millennial cliff retreat rates using cosmogenic nuclides in coastal colluvium: EGUsphere, p. 1–15, doi:10.5194/egusphere-2023-3020.
Hurst, M.D., Rood, D.H., Ellis, M.A., Anderson, R.S., and Dornbusch, U., 2016, Recent acceleration in coastal cliff retreat rates on the south coast of Great Britain: Proceedings of the National Academy of Sciences, v. 113, p. 13336–13341, doi:10.1073/pnas.1613044113.
Regard, V., Dewez, T., Bourlès, D.L., Anderson, R.S., Duperret, A., Costa, S., Leanni, L., Lasseur, E., Pedoja, K., and Maillet, G.M., 2012, Late Holocene seacliff retreat recorded by 10Be profiles across a coastal platform: Theory and example from the English Channel: Quaternary Geochronology, v. 11, p. 87–97, doi:10.1016/j.quageo.2012.02.027.
Swirad, Z.M., Rosser, N.J., Brain, M.J., Rood, D.H., Hurst, M.D., Wilcken, K.M., and Barlow, J., 2020, Cosmogenic exposure dating reveals limited long-term variability in erosion of a rocky coastline: Nature Communications, v. 11, p. 3804, doi:10.1038/s41467-020-17611-9.
How to cite: Regard, V., Swirad, Z., Chokrafi, I., Carretier, S., and Hurst, M.: Estimating long-term coastal cliff retreat using cosmogenic nuclides: Development of a user-friendly inversion tool, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2817, https://doi.org/10.5194/egusphere-egu25-2817, 2025.
Joint inversion within a Bayesian framework provides a robust means to estimate uncertainties by integrating the inherent variability of multiple data sets used in the inversion process. In this study, we reconstruct the surface uplift history of mantle origin in NW Iberia and quantify its associated uncertainties. Using a novel reversible-jump Markov chain Monte Carlo (RJ-MCMC) Bayesian algorithm, we perform a joint inversion of topographic data and river-sand 10Be concentrations in quartz to decode the uplift history. This probabilistic approach yields an ensemble of solutions that explore diverse combinations of model parameters, enabling detailed uncertainty quantification in the timing and magnitude of uplift rate changes.
Our forward model employs non-linear analytical solutions of the stream power incision model, which defines incision I = KAmSn as a function of S, the local channel gradient; A, the upstream drainage area; and K, the erodibility parameter. The model is coupled with the CAIRN method (Mudd et al., 2016, Earth Surface Dynamics, 4, 655-674) to invert Be-10 concentrations at the catchment scale to calibrate the K and n parameters with erosion rates.
We apply this methodology to the Atlantic rivers draining NW, where deep canyons dissect low-relief erosional surfaces formed over the last 100 million years, and apply the calibration to other settings in Central Iberia. Our results suggest that the transient topography reflects a regional late Cenozoic uplift of several hundred meters, likely driven by mantle-related, continent-scale processes. This study underscores the utility of probabilistic joint inversion in unraveling complex geodynamic histories and their uncertainties.
How to cite: Babault, J., Bodet, L., Arroucau, P., Charco, M., Figueiredo, P., Owen, L. A., Caffee, M., Fullea, J., Negredo, A., and Van Den Driessche, J.: Handling Uncertainties in Mantle-Driven Late Cenozoic Surface Uplift of NW Iberia Using Bayesian Joint Inversion of River Profiles and 10Be Cosmogenic Nuclide Concentrations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20102, https://doi.org/10.5194/egusphere-egu25-20102, 2025.
Posters on site: Tue, 29 Apr, 10:45–12:30 | Hall X3
Quartz is one of the most common minerals in the Earth’s crust and can be found in a large diversity of geological environments. Due to its ubiquity and resilience towards weathering, it is a major mineralogical component in terrestrial sediments. A good understanding of quartz properties can thus be very useful to understand quartz dynamics and thereby Earth surface dynamic processes such as erosion, transport and deposition.
Electron spin resonance (ESR) spectroscopy is a method which allows to characterize paramagnetic centres (unpaired electrons related to geochemical impurities) in quartz. Two paramagnetic centres generally present in quartz (Al and Ti-Li centres) are sensitive to ionizing radiation on the one hand and light exposure on the other hand and can be used to date the transport and deposition of quartz in the timescale of ca. 50 ka to 3 Ma making ESR dating of quartz an excellent tool to constrain quaternary geological processes.
While this method has continuously been developed and improved over the last decades, some key aspects of the method, notably the sample dependency of dose response and sensitivity, remain poorly understood, leading to difficulties or even impossibility to date some samples.
In this contribution, we aim to identify the influence of source-specific signature and sediment cycling on ESR dose response and sensitivity. Our research focuses on the well characterized Strengbach catchment in the Vosges mountains (NE France) which drains a large variety of quartz bearing rocks (granites, gneiss, sandstones). Quartz extracted from different bedrocks was analyzed geochemically by Laser ablation coupled to mass spectrometry (LA-ICPMS) and by ESR. Subsequently, the quartz was artificially irradiated and bleached in order to reproduce natural sediment cycling and reinvestigated by ESR. We discuss the observed ESR differences in relation with their geochemical signature and examine possible reasons for the observed results.
How to cite: Heller, B., Voinchet, P., Chourio Camacho, D. N., Aupart, C., Rixhon, G., Lach, P., Valla, P., Boulay, M., Rizza, M., and Tissoux, H.: ESR dating of quartz revisited: towards a better understanding of ESR sensibilities through investigation of different quartz types and experimental reproduction of sediment cycling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10339, https://doi.org/10.5194/egusphere-egu25-10339, 2025.
The Variscan basement units of the Bohemian Massif and other Variscan domains in Central Europe are thought to be less affected by Cenozoic tectonics. However, analyses using geomorphic indices and river profiles reveal spatial variations in the evolved topography in the Bavarian Forest, the southwestern segment of the Bohemian Massif. The geomorphic analyses suggest disequilibrium along drainage divides and in river profiles. It has been suggested that the topography in the southern parts of the Bohemian Massif has rejuvenated (Zebari et al., 2024). However, interpretations aimed at extracting tectonic signals from geomorphic analysis are inherently relative, and it is sometimes challenging to separate tectonic signals from climate signals or differential erodibility. To further quantify landscape dynamics in the Bavarian Forest, we estimated long-term watershed-averaged denudation rates from in-situ produced 10Be cosmogenic nuclide analysis of sand samples collected from outlets of 15 representative watersheds in the Bavarian Forest.
Our initial results indicate that watershed-averaged denudation rates in the Bavarian Forest range from 21.1 ± 2.4 to 40.5 ± 4.8 mm/kyr. These denudation rates represent a time period equivalent to the removal of approximately 60 cm of rocks, corresponding to about 15 kyr for the fastest-eroding watershed and about 28.5 kyr for the slowest one. There are spatial variations in the denudation rates, with the watersheds clustering into several distinct subregions. Overall, watersheds in the southeast, within or around the Ilz catchment, and those in the high-elevation areas of the Hinterer Bayerischer Wald, have relatively higher denudation rates than those in the central segment of the Vorderer Bayerischer Wald. Furthermore, notable differences are also found across the drainage divide between the Regen and Danube rivers in the adjacent watersheds, and these differences are consistent with the analysis of drainage divide dynamics using the χ (Chi) integral. Additionally, the calculated denudation rates also correlate with the topographic metrics of watershed and river profiles.
The same climatic conditions and minimal contrast in rock erodibility are expected for the adjacent watersheds in the Bavarian Forest; therefore, these denudation rates may represent a brief time window within a longer span of tectonic processes that shaped the relief there. Broad surface uplift of the Northern Alpine Foreland Basin and beyond, since prior to 6 Ma, and associated drainage network reorganization may have also affected the southern regions of the Bohemian Massif, resulting in the rejuvenation of topography in the Bavarian Forest, notably within its southeastern part. Thus, it is expected that the driving forces for the broad-scale recent surface uplift event(s), which affected the Bavarian Forest, also reactivated the major bounding faults.
References:
Zebari, M., Friedrich, A. M., Ludat, A. L., Kahle, B., Rieger, S. M., & Kübler, S. (2024). The role of late Cenozoic intraplate tectonic in shaping the topography of the Bavarian Forest, southwestern Bohemian Massif, Germany. Geologica Bavarica, 130: 35–55.
How to cite: Zebari, M., Wittmann, H., and Friedrich, A.: Late Pleistocene-Holocene denudation rates in the Bavarian Forest from in-situ produced 10Be cosmogenic nuclides , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5647, https://doi.org/10.5194/egusphere-egu25-5647, 2025.
Quantifying the magnitude of rapid changes in our past climate system is paramount to our awareness of the scale and impact of current and future climate change. While a number of proxies enable surface air temperature reconstructions, methodological limitations and preservation issues limit the spatial coverage and timeframe for which most of these can be sucessfully applied. As a result, for major changes in our climate system like the Pleistocene-Holocene transition including the rapid warming and environmenal adaptions following the Last Glacial Maximum (LGM), the lack of terrestrial records leads to increased uncertainty in reconstructions of continental temperature.
Recently, low-temperature thermoluminescence (TL) signals of feldspar (i.e., 200–280 °C) have been shown to be sensitive to terrestrial temperature fluctuations over geological timescales and can thus inform on past surface temperature in terrestrial settings (Biswas et al., 2020). Using physical principles best known from trapped charge dating, the trapped charge population can be used to infer paleotemperatures in the form of temperature histories through inverse modelling. For this, other time resolved relative temperature records such as the Greenland ice sheet 𝛿18O-, speleothem-, or pollen records can be used as additional constraints.
Applying the TL paleothermometry approach, we present first reconstructions of LGM surface air temperatures at central European study sites. Additionally, we benchmark improvements of the method against samples from stable temperature crustal environments, namely the KTB and MIZ-1 boreholes located in Germany and Japan, respectively. Our ultimate objective is to combine these data with other northern hemisphere samples to improve our understanding of the Euro-African LGM continental surface air temperature.
References
Biswas, R.H., Herman, F., King, G.E., Lehmann, B., Singhvi, A.K., 2020. Surface paleothermometry using low-temperature thermoluminescence of feldspar. Clim. Past 16, 2075-2093.
How to cite: Oehler, S., Schmidt, C., Niyonzima, P., King, G. E., Biswas, R. H., and Herman, F.: Thermoluminescence paleothermometry enables LGM surface temperature reconstruction at central European study sites, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6215, https://doi.org/10.5194/egusphere-egu25-6215, 2025.
Latest with the onset of the Neolithic period, humans have modified the landscape by farming, extracting natural resources, and reducing forest cover. Many studies have demonstrated that these human activities can increase the vulnerability of soils to erosion. However, the magnitude and duration to which such activities have reduced forest cover and accelerated soil erosion have been mainly based on proxy data derived from sediment and pollen records. In this study, we test a new methodological approach by coupling leaf wax isotope analyses with erosion rate measurements based on 10Be and 14C to investigate the impact of human activities during the Holocene on vegetation and erosion rates on the island of Elba, Italy. We hypothesize that meeting the substantial fuel demands for iron smelting on Elba Island, initiated by the Etruscans and subsequently continued by the Romans from the 4th century BCE onwards, exerted significant pressure on the island's forest ecosystems. This reduction of forest cover likely accelerated soil erosion processes, driven by the removal of vegetative cover essential for soil stability. To test our hypothesis, we measured cosmogenic 10Be and 14C in quartz from stream sediment samples to reconstruct changes in erosion rates during the Holocene. We complemented this with leaf wax isotope analysis (δ2H, δ13C) from floodplain sediment cores to explore vegetation and hydrological changes. Due to the shorter half-life of 14C compared to 10Be (~5.7 kyr and ~1.4 Myr, respectively), 14C records erosion on shorter time scales than 10Be. Apparent erosion rates obtained from the two nuclides show a marked offset: 14C apparent erosion rates of 129 to 1080 mm kyr -1 are up to two orders of magnitude faster than the corresponding 10Be erosion rates of 20 to 50 mm kyr -1. This discrepancy can be explained by a substantial increase in erosion toward modern times. To identify the timing of erosion change and thickness of soil loss, we apply a Markov chain Monte Carlo inversion with several simple erosion histories. These data allow us to compare the history of land use with vegetation change and the erosion response on a landscape scale.
How to cite: Cerón Espejo, N., Scherler, D., Bernhardt, A., Rohrmann, A., Bebermeier, W., Becker, F., Wittmann, H., Dunai, T., Fulop, R., and Ott, R.: Erosion rate response to the reduction of forest cover following metallurgical activities on Elba Island (Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10549, https://doi.org/10.5194/egusphere-egu25-10549, 2025.
Neotectonics of Eastern Türkiye is mainly characterized by immensely complex deformation patterns driven by the convergence between the Arabian Plate and the Eastern Anatolian Plateau. This apparent convergence accommodates a primary intraplate strike-slip fault system, encompassing the North Anatolian Fault Zone (NAFZ) and the East Anatolian Fault System (EAFS). Recent seismic events, such as the 24 January 2020 (Mw6.8) earthquake and the 6 February 2023 doublet earthquake (Mw7.7 and Mw7.6), dramatically highlight the structural intricacy of the region and signify that the conundrum is much broader than initially thought. The ruptures occurred after the two earthquake sets abruptly terminated the onset of the Pütürge segment residing in the EAFS. The segment splits the Şiro Valley in two and is hypothesized to accumulate strain, potentially driven by aseismic creep.
Our multidisciplinary investigations focus on the deformation and seismic potential of the Pütürge segment, emphasizing critical questions regarding its long-term slip rate, uplift rate, and past earthquake cycle. Geochronological methods, including Optically Stimulated Luminescence (OSL) and Radiocarbon (14C) dating methods, have been applied to Quaternary River terrace deposits along the Şiro Valley. Three distinct terrace levels (T0, T1, and T2) were identified by measuring stratigraphic sections, with thickness of approximately ~1 m, ~11 m, and ~12 m, respectively. These terraces, shaped by predominantly sinistral strike-slip movement with somewhat oblique components, stand out as geologic archives of tectonic and fluvial activity. The terrace deposits primarily consist of clays, silts, sands with organic material, gravels, and boulder stemming from the Maden Complex and Pütürge Metamorphics, rich in quartz and feldspar. Preliminary OSL dating employing the single-aliquot regenerative dose (SAR) technique on quartz grains from the T1 terrace yielded ages ranging from 11.42 ± 1.97 ka to 28.18 ± 3.00 ka at the Gölkan site and 12.82 ± 0.95 ka to 30.92 ± 4.85 ka at the Yazıca site, located on the northern and southern margins of the Şiro Valley, respectively. Further analyses of samples from additional terrace levels are still ongoing.
These preliminary yet clear findings suggest that the Pütürge segment has experienced significant post-Quaternary tectonic activity. Furthermore, the seismogenesis of the Pütürge segment, in conjunction with known geological information, raises another issue to consider. The fault's seismicity patterns and parameters will be examined in that sense. Spatial and temporal Gutenberg-Richter recurrence parameters are valuable knowledge that helps us to calculate the return periods of apparent and possible scenario earthquakes. The deformation pattern will be tested to see if it is used as a key indicator of how the Valley is heading through and evolving. As the fieldwork, lab tests, and computational modeling have been underway and are close to finalization, this study aims to present preliminary geochronological dating results inferred from Quaternary fluvial terrace formations. Also, it explores their implications for the seismic hazard and tectonic evolution of the East Anatolian Fault System. This study is fully supported by the Scientific and Technological Research Council of Turkey (TÜBİTAK; Project No:122Y266).
How to cite: Akgün, E., Softa, M., Nas, M., Yüksel, M., Spencer, J. Q. G., Sözbilir, H., Aksoy, E., Gürgöze, S., and Topal, S.: Evidence for Long-term Quaternary Tectonic Activity of the Pütürge Segment in the East Anatolian Fault System (EAFS) by Using Luminescence and Radiocarbon Dating Methods, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12012, https://doi.org/10.5194/egusphere-egu25-12012, 2025.
Cosmogenic nuclides measured in depth-profiles are a valuable tool for reconstructing the depositional and erosional history of sedimentary sequences. The burial ages of these sequences can be determined by measuring cosmogenic nuclide pairs such as 26Al and 10Be. However, some conventional approaches neglect post-burial nuclide production, a major source of error.
A new model, CosmoChron (Sørensen et al., 2024, Quat. Geochron. 85, 101618), enables a more versatile and comprehensive analysis by integrating nuclide data with independent age constraints, such as OSL dating or magnetostratigraphy. CosmoChron employs probabilistic inverse modeling, incorporating prior information about accumulation processes and sample origins. The forward model accounts for 26Al/10Be ratios, pre-burial conditions, radioactive decay, post-burial production, and unconformities, allowing for more precise reconstructions, including hiatuses at unconformities.
We demonstrate CosmoChron via two case studies: (1) a drill-core at Wapenveld (the Netherlands) penetrates the Early Pleistocene “Hattem” beds—thought to be among the earliest glacigenic deposits in Europe. The samples are from three distinct layers with several unconformities and a stratigraphic age constraint at the base. And (2) Fisher Valley (Utah, USA) contains samples from Early Pleistocene alluvial sediments with depth-profile burial ages published by Balco and Stone (2005, ESPL 30, 1051-1067). We recalculate the age-depth relationship, compare the methods, and explore the differences in the results.
We discuss the advantages and limitations of depth-profiles and CosmoChron, emphasizing its ability to provide detailed temporal reconstructions while requiring robust site-specific information.
How to cite: Ylä-Mella, L., Wagner, K., Sørensen, A. L., Knudsen, M. F., Busschers, F., Bakker, M., Eriksen, B. L., Andersen, J. L., Olsen, J., Margold, M., and Jansen, J. D.: Unraveling burial histories with CosmoChron, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12361, https://doi.org/10.5194/egusphere-egu25-12361, 2025.
Exposure dating has become a critical tool in addressing specific geoscientific challenges, including glaciology, active fault studies, and environmental reconstructions. Cosmogenic exposure dating (e.g., 36Cl) and luminescence surface exposure dating are widely used techniques, often complementing each other. In active tectonic studies across Türkiye, cosmogenic 36Cl dating has been applied extensively to active faults to elucidate paleoseismic histories and slip rates. Although luminescence surface exposure dating is relatively new in this context, its initial applications along the Manisa Fault in Western Türkiye have shown promising results. In this study, we focus on the Kalafat and Yavansu faults within the Kuşadası Fault Zone, which is considered the eastern continuation of the Samos Fault that ruptured during the 30 October 2020 earthquake. This region, characterized by N-S extensional tectonics with horst-graben structures and normal faulting, offers well-preserved fault scarps that serve as natural laboratories for exposure dating.
Preliminary luminescence depth profiling of scarp samples and optically stimulated luminescence (OSL) dating of associated colluvial wedges provide valuable insights into the paleoseismic history of these faults: (i) Luminescence profiling revealed stable signal limits at ~6 mm, with intensity increasing with depth; (ii) Calibration against prior cosmogenic dating yielded uppermost ages of ~15 ka for KF and ~8 ka for YF; (iii) OSL dating of colluvial wedge bases produced ages of 16.56 ± 1.77 ka for KF and 14.45 ± 0.74 ka for YF. These results indicate significant seismic activity along both faults during the Late Pleistocene, consistent with regional tectonic processes. This research underscores the utility of integrating luminescence surface exposure techniques with cosmogenic methods for refining paleoseismic chronologies. This study is fully supported by the Dokuz Eylül University Scientific Research Project (Project No. FBA-2023-3042).
How to cite: Softa, M., Şahiner, E., Spencer, J. Q. G., Sözbilir, H., Yüksel, M., Utku, M., Akçar, N., Kırallı, S., Yerli, B., Çakır, R., Büyüktopçu, F. M., and Deniz, F.: Luminescence Surface Exposure Dating and Paleoseismic Insights from the Kuşadası Fault Zone, Western Türkiye, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14332, https://doi.org/10.5194/egusphere-egu25-14332, 2025.
Cosmogenic nuclide concentrations are typically inverted for erosion and soil production rates under the assumption that these rates are temporally invariant, and that soil thickness is in steady state. Yet, transience in process rates and soil thickness is expected to occur in landscapes that are experiencing changes in land use, tectonic uplift, and climate. Pairing cosmogenic nuclides with different half-lives provides a means for resolving transience if process rates are sufficiently slow that radioactive decay is significant. Here, we examine 10Be and 26Al concentrations in quartz collected from saprolite at 6 positions along a hillslope transect in the Belgian Ardennes. This transect runs from a low relief paleosurface to the bottom of a catchment incised ca. 30 meters into the paleosurface. We find that all measured 26Al/10Be ratios are below the production ratio and that the ratio on the paleosurface is near secular equilibrium. Furthermore, all samples plot below the steady-state erosion line on an 26Al/10Be two-isotope plot. Given the geomorphic position of the site on a regional topographic high, it is unlikely that the 26Al and 10Be concentrations can be explained by burial by sediment to a depth sufficient to shut-off cosmogenic nuclide production. Rather, we model the isotope concentrations as resulting from transience in the soil production rate and soil thickness. The model indicates that the mean soil thickness over the integration timescale of the cosmogenic nuclide signal exceeds the modern measured soil thickness.
How to cite: Moore, A., Li, Y., Henrion, M., Christl, M., Gautschi, P., Jonard, F., Lambot, S., Van Oost, K., Opfergelt, S., and Vanacker, V.: Using paired cosmogenic 26Al and 10Be to study landscape transience in the Belgian Ardennes , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15019, https://doi.org/10.5194/egusphere-egu25-15019, 2025.
Understanding the temporal pace and spatial pattern of alluvial fan-river system evolution in front of active orogens would help us properly extract information of active tectonics and increase our resilience to landscape evolution of this habitable area. The northern piedmont of Chinese Tianshan, where the landscape is shaped by the interactions among fan building and abandonment, river aggradation and degradation and fault related fold growth. Comprehensive studies have been performed to delineate fan distribution, river incision and fold growth history. However, it is lack of investigation on the detailed spatial and temporal pattern of river channel evolution in a full aggradation and degradation cycle, which hinders formulating the law for alluvial system evolution. In this study, we address this question by using luminescence dating technique to constrain the chronological sequences of sandy samples collected from the terrace deposits. The architecture of the terrace deposits is characterized by upper very coarse gravels and cobbles (VCGC) unit and lower medium and coarse gravels (MCG) unit. The VCGC unit is attributed to the deposition during the incisional phase while the MCG unit is related to the aggradation phase of Jingou River. The coupled luminescence ages from VCGC and MCG units suggested a gradual and slow aggradation of 25 m sediments from 16 ka to 8 ka ago, which was followed by an almost instant incision around 5.5 ka ago by 25 m at least. These observations echo to the patterns unveiled by previous numerical studies. Further, the abandonment ages determined by employing the samples from the MCG unit of the most extensively distributed terrace surface T5 along the middle reach of Jingou river decrease in downstream direction from 16 ka to 5.5 ka, which poses an evidence of diachronous terrace formation. The implication of asymmetric degradation-aggradation phases and diachronous terrace formation will be discussed, with respect to the mass redistribution processes and active tectonics characterization of the alluvial fan and river system.
How to cite: Qin, J., Li, K., Chen, J., Liu, J., and Yao, Y.: Unconventional spatial and temporal pattern of alluvial river aggradation and degradation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16613, https://doi.org/10.5194/egusphere-egu25-16613, 2025.
Quantifying erosion and linking its topographic imprint to underlying controls is critical for understanding landscape evolution and sediment dynamics across time and space. Over the past decades, catchment-wide denudation rates from cosmogenic 10Be concentrations in river sediment emerged as a standard method for quantifying erosion. As such, 10Be-based erosion data have been instrumental in proposing different controlling mechanisms and processes for distinct mountain ranges. These include tectonic uplift, often modulated by periglacial processes, precipitation gradients, bedrock erodibility, landslide frequency, and most prominently, hillslope morphology, i.e., the slope angle. However, disentangling the individual effects of these processes has proven challenging, and often, the correlation between erosion rates and topography is observed only up to threshold values, e.g., slope angles <30° in the European Alps. One potential reason for this is that most data on the erosion rate are obtained for catchments on a regional scale (>101 to 103 km2), where sediment mixing and storage, as well as the (dis)connectivity and stochastic nature of sediment sources, obscure the influence of individual processes on local erosion dynamics.
Here we present 16 new detrital 10Be erosion rates from two nested river catchments in Switzerland: the Luetschine in the Alps and the Schwarzwasser in the Pre-Alps. Despite being close (<50 km between outlets), these catchments display significant differences in topography within and between them. While the Schwarzwasser catchments are characterized by gentle slopes (mean values <21°) and mean altitudes of <1500 m a.s.l., the Luetschine catchments drain the northern rim of the highly elevated Aar Massif, resulting in steeper (up to 37° for mean slopes) and higher (mean altitudes of >2000 m a.s.l.) landscapes. To investigate how these topographic variations influence erosion rates, we sampled sub-catchments with progressively smaller drainage areas ranging from over 340 km2 to less than 3 km2 in the smallest upstream tributaries.
Overall, our resulting detrital 10Be erosion rates for the entire catchments are, 3-4 times higher for the Luetschine catchment than for the Schwarzwasser. They align with the general regional trend and the first-order control by the topographic uplift rate inferred by previous studies. In more detail, even in the topographically homogeneous Schwarzwasser basin, where erosion rates generally correlate with the average slope angle, the erosion rates internally vary by up to a factor of two, with the delivery of landslide material to the stream being the primary control. In the Luetschine basin, which comprises highly heterogeneous landscapes, the erosion rates differ by a factor of up to five among sub-catchments. Here, the highest and lowest values are obtained from the smallest catchments, and they do not correlate with slope angles in these steeper catchments (> 30 ° mean slope). Instead, locally different mechanisms, such as peri-glacial and glacial erosion, effectively modulate erosion rates. These findings reconcile contrasting control mechanisms for mountain range scale erosion on a local scale within the close geographical vicinity of our study area. These results underscore the need to sample smaller catchments and to consider topographic heterogeneity to link erosion and topography in steep environments.
How to cite: Mair, D., von Allmen, J., Ruffiner, P., Binaghi, M., Schmidt, C., Garipova, S., Akçar, N., Christl, M., and Schlunegger, F.: Linking highly variable Detrital 10Be Erosion Rates to heterogeneous Topography in Small and Alpine Catchments, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18560, https://doi.org/10.5194/egusphere-egu25-18560, 2025.
