This session includes studies ranging from erosion rates, sediment provenance, burial and transport times, bedrock exposure, surface uplift rates, cooling histories and landscape dynamics to technical developments and novel applications of key Quaternary geochronometers such as cosmogenic nuclides and luminescence. We welcome contributions that apply novel geochronological methods, that combine geochronological techniques with numerical modeling or landscape evolution analyses, and that highlight the latest developments and open questions in the application of geochronometers to landscape evolution problems.
Orals: Fri, 8 May, 14:00–15:45 | Room -2.20
Erosion breaks down mountains, yet it is sediment transport that removes sediment and transforms landscapes. Quantifying the rates of sediment transport is a challenging task. Luminescence, traditionally a Quaternary dating method, offers a means to help us constrain sediment transport as a unique sunlight-sensitive tracer. One of the sediment transport properties that luminescence can potentially constrain is the characteristic transport lengthscale, or hop length, that describes the mean distance of transport between long-term storage events, or rest times. Here, I discuss considerations for using luminescence to estimate hop lengths and rest times with potentially heavy- and thin- tailed probability distributions. I present recent work modeling transport distance versus in-channel sunlight exposure and highlight recent contributions in the literature that show the impressive potential of luminescence sediment tracing.
How to cite: Gray, H.: Estimating sediment transport scales with luminescence as a sediment tracer, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15487, https://doi.org/10.5194/egusphere-egu26-15487, 2026.
The geomorphological evolution of landscapes is primarily governed by the coupled influence of tectonics and climate, with their relative dominance varying through time and space. In the Ladakh Himalaya, where active deformation intersects pronounced Quaternary climatic fluctuations, this coupling produces a distinct geomorphic signature. The Muglib Valley, formerly the outlet of Pangong Tso, demonstrates a system in which tectonic forcing initiated hydrological reorganisation, subsequently amplified by climatic variability. The region lies along the Karakoram Fault system, where oblique right-lateral slip with a vertical component (3–5 mm yr⁻¹) has modified basin geometry, offset valley alignments, and generated localised blockages that facilitated lake formation. Detailed geomorphic and sedimentological analyses across seven field sections reveal marked spatial variability: stacked gravels and conglomerates represent sustained fluvial aggradation, while thick fan and lacustrine deposits reflect progressive sediment overloading and hydrological stagnation, respectively. Optically Stimulated Luminescence (OSL) ages indicate a steady flow of water from Pangong Tso between ~54 ± 4.3 ka and 21 ± 3 ka. Thereafter, the channel was cut and eventually abandoned at ~9 ± 1 ka. The latter coincides with intensified monsoonal precipitation during the Holocene Climate Optimum, which enhanced sediment flux and triggered fan progradation, ultimately blocking the Muglib outlet. This geomorphic transformation converted Pangong Tso from an open to a closed basin, isolating an upstream catchment of ~2000 km² and terminating water and sediment supply to the Tangste River. The findings demonstrate that slow but persistent tectonic activity along the Karakoram Fault primarily governed drainage reorganisation, while monsoon intensification acted as an additive trigger that accelerated fan aggradation and hydrological isolation. The Muglib system thus provides an example of coupled tectonic–climatic feedback that has reshaped the fluvial architecture and sediment connectivity in the Trans-Himalayan landscape.
How to cite: Sagwal, S., Kumar, A., Srivastava, P., Saha, S., and Shahrukh, M.: Open to closed basin: tectonic and climatic feedback in the evolution of the largest Himalayan lake system , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-675, https://doi.org/10.5194/egusphere-egu26-675, 2026.
The dynamic Cape south coast of South Africa is widely recognised for its extensive occurrence of aeolian coastal dunes and older (cemented) aeolianites; the latter are thought to preserve records of dune formation spanning multiple glacial-interglacial cycles. However, existing records are dominated by Marine Isotope Stages (MIS) 1 and 5e ages. Extensive and (assumed) much older deposits have been identified, but are largely unstudied. By reconstructing their chronologies, we aim to generate new insights into coastal change during the Early to Middle Pleistocene and examine the factors that control long-term preservation of aeolianite deposits on a tectonically stable coastline. We anticipate preservation to be largely influenced by local topography and underlying geology.
Here we focus on the geomorphic history of Walker Bay, southwest of Cape Town. Our aim is to integrate a suite of geophysical (ground penetrating radar-GPR), geochemical (ICP-MS, SEM) and luminescence (TT-OSL (quartz) and post-IR-IRSL (K-feldspar)) dating methods to unravel the chronology, structure and provenance of dune sands within the embayment.
Initial results indicate an age range of ~1 million years to ~600,000 years. The applied methods TT-OSL, IR225, and IR290 show some results that are close to each other, while others vary outside the error range. We also observe several unusual aeolian deposits, some of which are far from the modern coastline and reach elevations of more than 250m above sea level (amsl). Other locations with closely juxtaposed aeolianites (dating to >600ka), substantially greater than any yet published for this coastline, and uncemented sands (late Pleistocene) dated to MIS-3, a period with fewer records & sea-levels were significantly lower than present. The results challenge existing models, which suggest that pulses of dune formation occurred primarily during the MIS-5 and MIS-1 highstands. Several questions arise as to the mechanisms of aeolianite formation/preservation at such heights and distances relative to the modern coast, and the results present further questions: Is Walker Bay Unique? Or are such complex suite deposits much more widespread? On this basis, we consider whether methodological and sampling limitations have led to a spatio-temporal biased record of long-term dune formation in this region. Or is it a completely different system than what has been observed on the coast before?
How to cite: Borde, H., Carr, A., Cawthra, H., and Cowling, R.: Extending the record of coastal aeolian landscape change into the Middle and Early Pleistocene: a multi-method comparison SAR-OSL, TT-OSL and post-IRIR, Walker Bay, South Africa, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-641, https://doi.org/10.5194/egusphere-egu26-641, 2026.
The scarcity of terrestrial temperature proxies has been a major challenge in the reconstruction of continental climate evolution throughout the Last Glacial Maximum (LGM) and the Pleistocene-Holocene transition. Understanding such extreme climatic conditions and major system shifts in Earth’s history is paramount for constraining climate sensitivity and predicting future climate evolution in the light of rising greenhouse gas concentrations.
Our research aims to develop a globally applicable method for temperature sensing during this timescale using the low-temperature (i.e., 200–280 °C) thermoluminescence (TL) signal of near-surface bedrock feldspar which has been demonstrated to be sensitive to terrestrial surface air temperature fluctuations over geological timescales (Biswas et al., 2020). As such, palaeothermometry represents one of few available proxies for terrestrial temperature and can aid in quantifying the magnitude of rapid climate changes on a more local scale.
While the theoretical feasibility of TL palaeothermometry has been demonstrated (Biswas et al., 2020), it still requires accurate validation on additional samples of well-constrained temperature history. Furthermore, the method has not yet been applied to a broad set of samples for temperature reconstruction purposes.
Our contribution aims to close this knowledge gap by benchmarking recent methodological improvements against samples from borehole sites located in Germany and Japan. We further present first surface air temperature reconstructions at a number of study sites, which we intend to use to constrain the evolution of altitudinal and latitudinal temperature gradients since the LGM. We show that TL palaeothermometry can be used to retrieve accurate rock and surface air temperatures and may now be more routinely applied.
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., Niyonzima, P., King, G. E., Biswas, R. H., Herman, F., Bernard, M., Margirier, A., Nalwanga, R., El-Raei, M., and Schmidt, C.: Development of a globally applicable palaeothermometry method based on luminescence: Advances in method development and validation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13563, https://doi.org/10.5194/egusphere-egu26-13563, 2026.
Constraining rock time–temperature histories below ~100 °C (corresponding to the upper ~3 km of the Earth’s crust) is crucial for understanding the interactions between tectonics, erosion, and climate over Quaternary timescales. However, reconstructing thermal histories spanning 104-10⁶ years within the ~25-75 °C temperature range remains a significant challenge. Trapped-charge dating techniques, such as Optically Stimulated Luminescence (OSL) and Electron Spin Resonance (ESR), enable measurement of different temperature-sensitive (< 100 oC) trapped charge dating signals within quartz minerals, thereby offering the potential to fill this temporal and thermal gap. Quartz OSL signals often saturate over timescales of ~104 years, while ESR signals saturate over longer timescales of ~106 years; used together, these methods provide a powerful tool for constraining cooling and exhumation histories over the Quaternary.
A key challenge in establishing quartz OSL and ESR thermochronometry as a robust method lies in the lack of reliable and comprehensive benchmark studies. This study addresses this limitation by investigating quartz from drill-core sediments in the Anadarko Basin (Oklahoma, USA) with a well-constrained temperature history (~30−80 oC) based on empirical calibration with a stable geothermal gradient. Down-core measurement of OSL and ESR signals show promising results exhibiting a systematic decrease in intensity with increasing temperature (and depth), with OSL signals reaching saturation in the lower temperature range. Here, we conduct a detailed investigation of sample-specific signal saturation limits, thermal decay kinetics and temperature-sensitivity of OSL and ESR signals, followed by inversion of these different trapped charge signals for temperature. Our results provide a comprehensive and robust benchmark study to assess the potential and limitations of quartz OSL and ESR thermochronometry for reconstructing temperature histories in natural settings.
How to cite: Dave, A. K., Kranz-Bartz, M., Jepson, G., Bernard, M., Schmidt, C., Margirier, A., and King, G. E.: Quartz luminescence and ESR thermochronometry of drill-core sediments from the Anadarko Basin, USA, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8126, https://doi.org/10.5194/egusphere-egu26-8126, 2026.
The timing and drivers of canyon incision across the Colorado Plateau are strongly debated, particularly the roles of deep-seated processes, tectonics, geological inheritance, and climate. A major limitation in resolving canyon incision histories and their controlling processes is that the amount of exhumation associated with incision is often too small to be robustly recorded by classical low-temperature thermochronometers such as apatite fission track and (U–Th)/He. Resolving the timing of exhumation acceleration and onset of canyon incision therefore requires thermochronological tools sensitive to lower temperatures and shorter timescales, such as electron spin resonance (ESR).
Here, we focus on Zion Canyon, an emblematic and well-studied canyon on the western margin of the Colorado Plateau, to evaluate the potential of ESR thermochronology to resolve late Cenozoic to Quaternary exhumation/incision histories. Classical low-temperature thermochronometers suggest that exhumation began around 7 Ma. This exhumation signal integrates regional plateau denudation and canyon incision, preventing the isolation of incision-specific dynamics. In contrast, independent geomorphic constraints document significantly higher incision rates over the last ~1 Myr, implying temporal variations in incision that cannot be resolved with classical thermochronology.
We apply ESR thermochronology to a bedrock elevation profile from Zion Canyon to (i) quantify Quaternary incision rates and (ii) test for changes in cooling rates associated with canyon incision. Preliminary ESR results reveal an increase in cooling rates at ~3–2 Ma, suggesting an acceleration of incision during the late Pliocene–early Pleistocene. These results highlight the potential of ESR thermochronology to bridge the temporal gap between geomorphological constraints and classical thermochronology, and to provide new quantitative constraints on the timing and rates of canyon incision across the Colorado Plateau. In addition, preliminary data from the Grand Canyon (where the incision history is particularly complex and controversial) suggest that ESR signals are not saturated, highlighting the method’s potential to resolve cooling and exhumation over the last few million years in other canyons.
How to cite: Margirier, A., Dave, A. K., Jepson, G., Thomson, S., Valla, P. G., Voigtländer, A., Schmidt, C., and King, G. E.: Bridging classical low-temperature thermochronology and geomorphology: ESR thermochronology constraints on Plio-Quaternary exhumation and canyon incision across the Colorado Plateau, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12968, https://doi.org/10.5194/egusphere-egu26-12968, 2026.
High-relief great escarpments are prominent geomorphic features characterizing many passive continental margins, extending for hundreds to thousands of kilometers subparallel to the continent-ocean boundary and connecting coastal plains with upland plateaus. Initial formation of these escarpments is most often attributed to oceanic rifting preceding passive margin development. However, in many cases, including our study area in SE Australia, these escarpments have persisted for tens to hundreds of millions of years after rifting, raising questions about their geomorphic origin and evolution. One of the challenges to understanding the evolution of great escarpments is that erosion-driven exhumation produced during their retreat from the coast is expected to be too small in magnitude to be recorded by conventional thermochronometers, such as apatite fission track (AFT). Here, we present apatite 4He/3He thermochronology results from a bedrock transect across the SE Australian escarpment. Existing AFT and conventional (U-Th)/He data in SE Australia appear to lack sufficient resolution to fully document the timing of cooling associated with escarpment retreat. Apatite 4He/3He thermochronology, on the other hand, is sensitive to temperatures as low as 35 ºC, making it suitable for detecting cooling signals from the estimated 1-1.5 km total exhumation associated with escarpment retreat in this region. Preliminary thermal history models based on our initial apatite 4He/3He data document an increase in cooling rates across the coastal plain ca. 120-80 Ma. This late Cretaceous signal overlaps with the initiation of rifting of the Tasman Sea and is consistent with a plateau degradation style of escarpment evolution, where the escarpment formed and retreated to near its present-day position rapidly after rifting. Ongoing acquisition of additional apatite 4He/3He data will allow us to further assess the extent of late Cretaceous cooling along the coastal plain and better constrain landscape evolution models of escarpment development.
How to cite: Zhan, W., Gong, L., Tremblay, M., Curry, M., and McMillan, M.: Post-rift evolution of the southeastern Australia Great Escarpment from apatite 4He/3He thermochronology, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-565, https://doi.org/10.5194/egusphere-egu26-565, 2026.
The rate of bedrock river incision both regulates and depends on the size distribution of sediment produced on hillslopes. Quantifying how hillslope sediment size varies across catchment scales is therefore fundamental to understanding feedbacks between weathering, erosion, and tectonic uplift in mountain landscapes. Here, we quantify spatial variations in hillslope sediment size distributions within a steep mountain catchment using a numerical model that combines a granulometric analysis of detrital cosmogenic nuclide and apatite (U–Th)/He age measurements from each of twelve sediment size classes ranging from medium sand to boulders. The model accounts for sediment production, mixing, and particle size evolution during transport using particle-wear relationships calibrated from tumbling experiments conducted in rotating wheels of varying size. Because these experiments span five orders of magnitude in calculated sediment energy, they enable upscaling of measured abrasion and fragmentation relationships from laboratory to field conditions.
Measured age distributions by size class show excesses and deficits relative to spatially uniform erosion that we detect using a Monte Carlo-based departure analysis. For example, cobbles at the outlet are relatively old and thus preferentially derived from higher elevations while boulders are relatively young and thus preferentially derived from lower elevations. When these granulometric elevation distributions are combined with measured granulometric variations in cosmogenic nuclides, our model predictions are consistent with independent field-based measurements of hillslope sediment size distributions and their spatial variability across the catchment. Hence, the measured size-dependent variations in cosmogenic nuclides at our study site need not be attributed solely to depth-dependent shielding of relatively coarse material on steep hillslopes. Instead, the granulometric variability in isotopic tracers can be explained by the linkage between erosion rate and particle size production. Together, these results demonstrate that coupling granulometric cosmogenic nuclides and tracer thermochronology with empirically calibrated particle-wear relationships provides a powerful framework for predicting spatial variations in sediment production and erosion in mountain landscapes.
How to cite: Riebe, C., Sklar, L., and Lukens, C.: Hillslope sediment size distributions revealed by granulometric cosmogenic nuclides, detrital thermochronology, and experimentally calibrated particle wear relationships, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15046, https://doi.org/10.5194/egusphere-egu26-15046, 2026.
Past glacier fluctuations can be reconstructed successfully via cosmogenic nuclide exposure dating of boulders protruding from the moraine surface. However, post-depositional processes like denudation, slope failure and weathering, together with nuclide inheritance, potentially affect nuclide concentrations and diminish the accuracy of moraine age estimates. Post-depositional exhumation of boulders leads to incomplete cosmic-ray exposure and thus underestimated ages. Conversely, some boulders contain nuclides produced prior to their deposition (nuclide inheritance) due to insufficient depth of glacier erosion, incorporation of older glacigenic sediments or material from surrounding non-glaciated areas. Nuclide inheritance yields age estimates older than the true age of moraine formation.
With an aim to evaluate the controls on moraine denudation and to gain insights to the reliability of exposure dating and sampling strategy, we compiled a global dataset of 10,083 10Be-based exposure dates from the Expage database. Clustering of exposure ages from each moraine was used as an indicator of dating quality, assuming that boulders without prior or incomplete exposure should yield a well-clustered (MSWD<2) age. Moraine age-clustering was analysed with respect to climate, topography, location and type of ice mass.
We find that just 23% of moraine ridges with at least three exposure dates show well-clustered exposure ages, increasing to 69% after iterative removal of outliers with the highest deviation. Exposure-age clustering is mainly a function of moraine age: clustering is best among moraines of 15–10 ka age and decreases notably for moraines that are either younger or older. Climate also matters: well-clustered moraine ages are more frequent in regions with milder climates experiencing higher mean annual temperature and precipitation and lower annual temperature range. Conversely, poorly-clustered ages (e.g. Antarctic Ice Sheet, Cordilleran Ice Sheet, northeastern Asia, High Mountain Asia and Greenland) appear to reflect aridity, extreme cold, or large annual temperature range, but may also stem from complex glacial histories involving multiple glacier readvances.
A key implication for moraine boulder sampling strategies is the effect of the number of samples per moraine. While 36% of the examined moraines comprise only three samples, the likelihood of obtaining a well-clustered age increases significantly by sampling four. The optimal number of samples varies with moraine age and climate. For moraines dated to 20–10 ka, four samples are generally sufficient, whereas younger or older moraines typically require seven or more samples to achieve a similar level of accuracy. The optimal number of samples increases toward colder climates, from temperate (3–4 samples or more) through boreal (5–6 samples or more) to polar climates (7 or more).
How to cite: Jandová, A., Stoker, B. J., Margold, M., and Jansen, J. D.: Controls on moraine exposure-age clustering and implications for sampling strategy, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18749, https://doi.org/10.5194/egusphere-egu26-18749, 2026.
Posters on site: Fri, 8 May, 08:30–10:15 | Hall X2
Luminescence dating of rock surfaces is an emerging and exciting branch of research in geochronology with great application potential. In principle the technique can be used to date hitherto undatable geological and archaeological materials or geomorphological landscape elements. As such, luminescence-based rock surface dating (RSD) is highly complementary to OSL sediment burial and other Quaternary dating techniques.
RSD basically comes in two variants: rock surface burial dating (RSbD) and rock surface exposure dating (RSeD), both being highly active and promising geochronological research strands undergoing methodological development, refinement and testing. Meanwhile numerous ways of analyzing RSb and RSe luminescence data exist and different approaches to calculate rock surface ages have been introduced, yet no standardized way of handling RSb or RSe luminescence data has been put forward.
Here we present an open-source software package that is based on the software language Python©. The program enables users to evaluate their rock surface luminescence data via a simple graphical user interface (GUI). The program allows processing of data which originate either from CCD or EMCCD images or from the conventional "drilling and slicing" approach and takes various types of OSL, IRSL and IRPL signals into account. We incorporated all currently available and stat-of-the art bleaching models into the software package and provide the user with maximum degree of flexibility for normalizing luminescence signals. In the case of RSeD different calibration procedure options are implemented. Ultimately, the software allows single as well as multiple exposure and burial ages from rock surfaces to be derived.
How to cite: Meyer, M., Freiesleben, T., and Riedle, T.: The Python time machine – an open source software application for luminescence-based rock surface dating, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22933, https://doi.org/10.5194/egusphere-egu26-22933, 2026.
The geomorphic and sedimentological evolution of the dynamic Satluj River basin is understood through a detailed analysis that combines comprehensive morpho-sedimentary mapping, lithofacies analysis, and optically stimulated luminescence (OSL) dating to evaluate the impact of base-level fluctuations. Although the valley is far from the current coastline, evidences of minor changes in base level caused by climate and sea level processes reach deep into the hinterland is clearly seen in such a dynamic mountain catchment of the Himalaya. These changes majorly control river dynamics, sediment transport, and overall landscape evolution. Frequent landslides, temporary channel damming, lake formation, and large fluvio-lacustrine sedimentary successions direct periods of enhanced sediment input and aggradation. Morphotectonic indices and the presence of seismites in these deposits suggest significant tectonic influence on base-level-driven geomorphic responses.
Optical chronology identifies two major aggradation phases: one from about 30 to 24 ka and another from about 17 to 11 ka. During these phases, more sediment was deposited, less material was transported, and the local base level temporarily rose owing to valley damming. In these periods, the landscape was unstable, resulting in numerous mass-wasting events, the creation of dammed palaeolakes, and the preservation of extensive sedimentary records. Subsequent incision stages form strath terraces, vertically incised gorges, offset channels, and modifications in the shape of Quaternary sediments. This indicates that the base level declined again and tectonic activity resumed.
The observed relationship between aggradation-incision cycles, dammed lakes, and tectonically influenced base-level fluctuations demonstrates how climate-driven base-level modifications can be greatly amplified in dynamic mountain belts. The findings suggest that base-level signals connected to sea-level fluctuations may have an indirect impact on sedimentation and geomorphology over significant distances upstream through complex sediment-routing systems. This study adds new constraints on late Quaternary catchment-scale geomorphic adjustment and improves understanding of how sea-level-induced base-level changes interact with tectonics, landslides, and fluvial processes to shape the Himalayan landscape.
How to cite: Shahrukh, M. and Kumar, A.: Propagation of Base-Level Signals into an Active Himalayan Catchment: Morpho-Sedimentary and OSL Evidence from the Satluj River Valley, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-730, https://doi.org/10.5194/egusphere-egu26-730, 2026.
The deglaciation history of the European Alps is thought to be well established, however, the timing of glacier retreat in the eastern Alps remains poorly constrained. Here, we present the first 10Be exposure ages from the Klagenfurt Basin (Carinthia, Austria), which was covered by the piedmont lobe of the Drau glacier during the Last Glacial Maximum (LGM). The 10Be ages were obtained from glacially polished quartz veins between ~530 and ~800 m a.s.l. and range from 17.4±0.6 to 13.5±0.7 ka (mean age: 15.9±1.0 ka). The age data indicate that deglaciation of the Klagenfurt Basin occurred near the end of the Oldest Dryas stadial and are consistent with published 10Be ages from the flat tops of the ~2000-m-high Nock Mountains farther north (mean age: 15.0±1.2 ka) (Wölfler et al., 2022). Both data sets refute a widely accepted scenario, in which the southeastern Alps were already ice-free by ~19-18 ka (e.g., van Husen, 1997; Reitner, 2007; Ivy-Ochs et al., 2023). Our reassessment of the underlying age constraints for this still prevailing view shows that the respective 14C ages were obtained from bulk-sediment samples in two postglacial lakes (Lake Längsee: Schmidt et al., 1998, 2002; Lake Jeserzer See: Schmidt et al, 2012). 14C ages from bulk lake-sediment samples are, however, known to overestimate the true sedimentation age due to a reservoir effect (e.g., Ilyaschuk et al., 2009; Hou et al., 2012). At Lake Längsee, the overestimation of the true sedimentation ages by the 14C ages is confirmed by a layer of Neapolitan Yellow Tuff, whose age was independently determined by 40Ar/39Ar dating at its origin (Deino et al., 2004). Later deglaciation than previously assumed is further supported by two published 10Be age data sets from the Hohe Tauern mountains, which indicate LGM ice-surface lowering between ~18.6 and ~14.8 ka (Wirsig et al., 2016) and rock-glacier stabilization at ~16-14 ka (Steinemann et al., 2020), respectively. Our interpretations agree with palaeo-precipitation records derived from cave carbonates, which indicate enhanced autumn and winter precipitation during the LGM and until ~17 ka (Spötl et al., 2021; Warken et al., 2024). The combined evidence presented in our study shows that deglaciation of the southeastern Alps occurred at ~16-15 ka and hence later than previously thought.
References
Deino et al., 2004, J. Volcanol. Geotherm. Res., 133, 157–170, doi.org/10.1016/S0377-0273(03)00396-2.
Hou et al., 2012, Quat. Sci. Rev., 48, 67–79, doi.org/10.1016/j.quascirev.2012.06.008.
Ilyaschuk et al., 2009, Quat. Sci. Rev., 28, 1340–1353, doi.org/10.1016/j.quascirev.2009.01.007.
Ivy-Ochs et al., 2023, In: European Glacial Landscapes—The Last Deglaciation, 175–183, doi.org/10.1016/B978-0-323-91899-2.00005-X.
Reitner, 2007, Quat. Int. 164/165, 64–84, doi.org/10.1016/j.quaint.2006.12.016.
Schmidt et al., 1998, Aquat. Sci. 60, 56-88.
Schmidt et al., 2002, Quat. Int., 88, 45–56.
Schmidt et al., 2012, J. Quat. Sci. 27, 40–50. doi.org/10.1002/jqs.1505.
Spötl et al., 2021, Nature Commun. 12, 1839, doi.org/10.1038/s41467-021-22090-7.
Steinemann et al., 2020, Quat. Sci. Rev. 241, 106424, doi.org/10.1016/j.quascirev.2020.106424.
Warken et al., 2024, Comm. Earth Environ. 5, 694, doi.org/10.1038/s43247-024-01876-9.
Wirsig et al., 2016, Quat. Sci. Rev. 143, 37–50, doi.org/10.1016/j.quascirev.2016.05.001.
Wölfler et al., 2022, J. Quat. Sci., 37, 677–687, doi.org/10.1002/jqs.3399.
How to cite: Hampel, A. and Hetzel, R.: Deglaciation of the Klagenfurt Basin (Austria): constraints from 10Be exposure dating and implications for the glacial history of the southeastern Alps, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1613, https://doi.org/10.5194/egusphere-egu26-1613, 2026.
The uplift of the Rhenish Massif is recorded by strath terraces along major rivers, however, absolute age control for the terraces is still scarce, and terrace correlations with Quaternary climate cycles are uncertain and partly contradictory. Along the Rhine, two terrace levels – the Older and Younger Main Terrace (OMT and YMT) – occur above a marked break-in-slope, which separates a steep lower valley from a broad upper valley with gentle slopes. Based on limited paleomagnetic data, an age of 730–800 ka for the YMT was often assumed and used to estimate rock uplift (e.g., Meyer & Stets, 1998). Here, we present the first 10Be – 26Al isochron-burial ages for the OMT and YMT at two sites: Kasbach-Ohlenberg and Bad Hönningen. At Kasbach-Ohlenberg, the OMT yields a burial age of 1.4–1.6 Ma, while the YMT is dated to 0.7–0.8 Ma. These ages and the small vertical distance of only a few meters between both terraces indicate a prolonged period with little river incision, followed by a phase of more rapid incision and rock uplift. The elevation of the bedrock strath of the YMT above the Rhine (i.e., ~160 m) implies an average uplift rate of ~200 m/Ma during this phase. At Bad Hönningen, the OMT yields a burial age of 1.1-1.4 Ma. This younger age and the higher elevation of the OMT at this site suggest that rock uplift increases toward the internal part of the Rhenish Massif. The temporal coincidence between the onset of uplift and plume-related intraplate volcanism in the Eifel at ~700 ka (e.g., Lippolt et al., 1983) suggests a mantle-driven origin for the uplift. Our ongoing work will result in additional age–elevation data for terrace sites along the Rhine, thus enabling a more detailed reconstruction of the timing, rate, and spatial variability of uplift in the Rhenish Massif.
References
Lippolt, H.J., 1983. Distribution of volcanic activity in space and time. In: Fuchs, K., von Gehlen, K., Mälzer, H., Murawski, H., Semmel, A. (Eds.), Plateau Uplift. Springer, Berlin, pp. 112–120.
Meyer, W., Stets, J., 1998. Junge Tektonik im Rheinischen Schiefergebirge und ihre Quantifizierung. Z. dt. geol. Ges. 149, 359–379. https://doi.org/10.1127/zdgg/149/1998/359.
How to cite: Terraza, M., Wolff, R., Hetzel, R., Ritter, B., Binnie, S., Preuss, J., Hoselmann, C., Weidenfeller, M., and Heinze, S.: Accelerated uplift of the Rhenish Massif (central Europe) since 700–800 ka revealed by isochron-burial dating of strath terraces, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1787, https://doi.org/10.5194/egusphere-egu26-1787, 2026.
In areas of multiple exposure-burial histories the use of two cosmogenic radionuclides (CRN) with different half-lives allows to reveal the disequilibrium between CRN concentrations and provide a better understanding of landscape evolution. This study aims to quantify bedrock denudation rates in the Western Mecsek Mts (southern Pannonian Basin), a low-elevation hilly area that is currently being exhumed from under its loess cover deposited during the Quaternary glaciations. Concentrations of 10Be and 26Al were measured in samples taken from flat, soil-covered ridge tops and stream sediments from several small river catchments composed of Permian and Triassic sandstones and conglomerates. Low 26Al/10Be ratios are indicative of unsteadiness caused by significant past burial of the bedrock surfaces. A Monte Carlo (MC) model was developed to reveal the temporal evolution of the loess cover as a function of glacial-interglacial climate, and to determine the true rate of bedrock denudation accounting for both loess-covered periods with shielding and zero erosion as well as phases of exposure and bedrock denudation during periods without loess.
Our model showed that higher-elevation catchments and ridges were exposed for 40 to 85%, while lower-elevation areas were uncovered for less than 30% of time during the last 1 Ma. The modelled time integrated bedrock denudation rates were similar for the ridge crests and basin-averaged samples suggesting a steady relief. However, a well-expressed difference was found between the areas spending most of the time loess covered and the less covered group with mean integrated denudation rates of 5±5 m/Ma and 19±8 m/Ma, respectively. Single nuclide 10Be denudation rates overestimated the modelled, time-integrated denudation rates by a factor of ~1.5 for the more exposed group and by a factor of ~13 (up to >30) for the mostly covered areas. These rates, especially the latter, are slower than published values for similar climatic, tectonic, and topographic settings. If the simple, single nuclide 10Be approach was used, these differences would have remained hidden, and the true lowering rate of bedrock would have been overestimated by a factor that increases with the shielding time.
This is the first study quantifying the influence of past loess covers on CRN concentrations in bedrock and to estimate the denudation rates corrected for this shielding. Our findings reveal that the steady-state assumption of the CRN concentrations may also be violated in small, non-glaciated catchments without intermittent sediment storage. Where single-nuclide 10Be denudation rates are higher than sediment-trap estimates, the shielding effect of past sediment cover (such as loess) could also explain the discrepancy. Accordingly, we recommend the use of the paired 26Al/10Be approach to test the presumption of cosmogenic nuclide equilibrium not only in large catchments and formerly glaciated areas, but also in settings where past sediment cover may have lasted long enough to lower the CRN ratio.
Funding: PURAM, Mecsekérc Ltd., NKFIH project FK 124807. Sample processing: Cosmogenic Laboratories of Budapest (n=16) and of the University of Edinburgh (n=4); AMS measurements: ASTER, Aix en Provence (n=16) and SUERC, Glasgow (n=4)
How to cite: Ruszkiczay-Rüdiger, Z., Knudsen, M. F., Bauer, M., Telbisz, T., Team, A., and Sebe, K.: Quantification of Quaternary loess cover and integrated denudation rates using cosmogenic nuclide Aluminium-26 and Beryllium-10 disequilibrium (Mecsek Mountains, Pannonian Basin), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2959, https://doi.org/10.5194/egusphere-egu26-2959, 2026.
Over the past decade, several research groups have developed and applied methods for using Infra-Red Stimulated Luminescence (IRSL) from sand-sized grains of alkali feldspar collected from the active channels of different rivers. These methods used either conventional multiple grain IRSL measurements, or single grain IRSL determinations, but all depend on comparisons of results from different sampling locations to reconstruct virtual velocity. In its simplest form, this approach relies on the Ergodic principle as the basis for time-space equivalence of different samples. While this can often represent a successful approach, recent anthropogenic disturbances to fluvial systems may in some cases render this method problematic. For example, where channel engineering or dam construction cuts off or modifies the natural sediment supply, samples collected downstream of these locations may provide signals that are inconsistent with those from upstream.
For this reason, our research team has been developing IRSL approaches to attempt to reconstruct sediment storage times and virtual velocity by inverting measured Multiple Elevated Temperature (MET) IRSL signals from single grains of alkali feldspar. Some grains preserve a record that is shaped by multiple episodes of storage during burial and light exposure during transport; storage causes trapped charge populations responsible for IRSL signals to grow in a predictable manner, while light exposure causes a reduction in each population. Multiple IRSL signals measured at a range of temperatures in the laboratory display different sensitivity to light, resulting in different degrees of “bleaching” (reduction in trapped charge). When a grain is subject to multiple episodes of burial and bleaching, the different IRSL signals move away from being in an equilibrium ratio with each other, allowing us to constrain their past burial and bleaching histories, within some limits. In this presentation, we shall compare results from this novel single grain MET-IRSL inversion approach with conventional IRSL sediment transport approaches, and assess performance from grains subject to laboratory simulations of different burial-bleach cycles. The new technique has great potential to help understand contemporary and past fluvial dynamics and sediment storage, as well as determination of sediment sources and channel erosional processes, and can contribute significantly to applications such as catchment carbon dynamics, or assessing impacts of engineering structures.
How to cite: Rhodes, E. and Spano, T.: Reconstructing virtual velocity and fluvial dynamics using MET-IRSL from single grains of sand, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4552, https://doi.org/10.5194/egusphere-egu26-4552, 2026.
Luminescence ages are powerful agents for tracing past sediment dynamics and deciphering complexities inherent in the evolution of past landscapes. If applied in temporal periods suitable for luminescence-based methods, they provide accurate dating results but with somewhat limited spatial resolution. This is primarily due to the time-consuming nature of luminescence sample preparation and measurement procedures. Luminescence screening methods, for instance, using portable equipment [1] that focuses only on light intensities rather than absorbed dose/dose-rate ratios, provide a convenient shortcut. Assuming a suitable geologically homogeneous environment, they provide initial insights and relative chronologies and can be useful in developing an appropriate sampling strategy for a more detailed study.
However, the hope of delivering, even provisionally, instant chronologies could not yet be satisfied. While our approach similarly cannot offer instant chronologies, we propose here a gradient-boosted decision tree approach [2] to model the complex interactions among physical parameters (e.g., dose rate, water content, sedimentology) and convert luminescence intensity values into the age domain. Our approach uses age-depth relationships of ages and intensities from different profiles, combined with additional features such as geographical information (latitude, longitude, depth below ground surface). We demonstrate that we can satisfactorily and robustly predict pseudo-luminescence ages from signal intensities using only a small training dataset (n = 31). This enables us to considerably enhance the age resolution of luminescence dating chronologies in suitable environments, particularly in those where sedimentary deposits are relatively homogenous.
A limitation of our approach is our reliance on a favourable, homogeneous sampling environment (here, sandy deposits of aeolian origin), which cannot be directly transferred to other geologically more complex settings; however, we are confident that the general approach remains valid and can be adapted on regional scales to increase age resolution.
References
[1] Sanderson, D. C. W. and Murphy, S.: Using simple portable OSL measurements and laboratory characterisation to help understand complex and heterogeneous sediment sequences for luminescence dating, Quaternary Geochronology, 5, 299–305, https://doi.org/10.1016/j.quageo.2009.02.001, 2010.
[2] Chen, T. and Guestrin, C.: XGBoost: A Scalable Tree Boosting System, in: Proceedings of the 22nd ACM SIGKDD International Conference on Knowledge Discovery and Data Mining, New York, NY, USA, 785–794, https://doi.org/10.1145/2939672.2939785, 2016.
How to cite: Kreutzer, S., Heydari, M., Hanson, P. R., Kadereit, A., Mahan, S. A., and Schmidt, C.: A gradient boosted decision tree approach for high-resolution luminescence chronologies, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5323, https://doi.org/10.5194/egusphere-egu26-5323, 2026.
The Thermochronology @ Purdue (T@P) noble gas mass spectrometry facility was established at Purdue University between 2020 and 2023. In this presentation, we will detail the T@P laboratory’s instrument configuration and demonstrate the facility’s capabilities for both helium-based thermochronometry and cosmogenic noble gas geochemistry. The primary instrument in the T@P laboratory is an Isotopx NGX, a multi-collector sector field mass spectrometer with a Nier-type source, which has a custom detector configuration consisting of three discrete dynode electron multipliers, including one fitted with an electrostatic filter, and two Faraday cups with ATONA® amplifiers. The NGX is connected to a custom-built, fully automated, ultra-high vacuum extraction line that includes an activated charcoal cryogenic trap and two getters for gas purification, two manometrically-calibrated gas standards for sensitivity calibration (air and 3He-enriched helium), and a manometrically-calibrated 3He spike for measurements of radiogenic 4He by isotope dilution. Gases are extracted by heating samples under vacuum using a diode laser system in a feedback control loop with either a calibrated optical pyrometer (better than ± 10 ºC precision), or a bare, thin-wire thermocouple in contact with the sample (better than ± 3 ºC precision). We will present isotopic analyses made in the T@P laboratory of reference materials for both helium-based thermochronometry (Durango apatite) and cosmogenic noble gas geochemistry (CRONUS-P, CRONUS-A, CREU-1) as well as from example applications in Earth and planetary surface processes.
How to cite: Tremblay, M. M., Guo, H., Dziekonski, E. T., Ickert, R. B., and Blair, D.: Helium-based thermochronometry and cosmogenic noble gas geochemistry in the Thermochronology @ Purdue (T@P) noble gas mass spectrometry facility, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5827, https://doi.org/10.5194/egusphere-egu26-5827, 2026.
Sufficient temperature rise during frictional heating is a key parameter controlling whether luminescence dating of fault gouges can determine the timing of past earthquakes. Regardless, the true temperatures induced in the rock during a co-seismic slip event are often unknown. This significantly hampers the accuracy of luminescence age results from fault gouges. Laboratory-controlled friction experiments can adequately simulate different friction scenarios by modulating normal stress and slip velocity and then recording induced temperatures using thermocouples [1] or an infrared camera [2]. However, monitoring those events in nature is highly impractical for past events.
Systematic luminescence studies on ultraviolet (UV) radiofluorescence (RF) of quartz reported a strong correlation between heating and subsequently recorded UV-RF signaldynamics [3,4].
Here, we explore the potential of UV-RF to shed light on the extent of friction-induced temperature in quartz-bearing host rocks. In our experiments, we tested one sediment quartz sample with a known luminescence characteristic and a polymineral sample from the North Tehran Fault. For one part of each sample, we first recorded a UV-RF temperature profile after heating subsamples in batches from 30 ºC to 575 ºC in increments of 25 ºC. The other (untreated) part was then subjected to frictional heating in the laboratory under a normal stress of 12 MPa and a slip velocity of 5 cm/s using a rotary shear apparatus. During the experiment, the frictional heat was recorded using an infrared camera. We then measured the UV-RF signal and projected the results onto the signal-preheat profile to estimate the (unknown) frictional heat temperature.
Although our study is preliminary at this stage, we could calculate realistic friction-induced temperatures for the quartz sample. In contrast, the UV-RF signals of the polymineral sample will require additional experiments. We will present the experimental design and initial results, and discuss the challenges and the potential of our approach for tracking the temperature levels generated by earthquakes.
References
[1] Kim, J.H., Ree, J.-H., Choi, J.-H., Chauhan, N., Hirose, T., Kitamura, M., 2019. Experimental investigations on dating the last earthquake event using OSL signals of quartz from fault gouges. Tectonophysics 769, 228191. https://doi.org/10.1016/j.tecto.2019.228191
[2] Heydari, M., Kreutzer. S., Hung, C.C., Martin, L., Ghassemi, M.R., Tsukamoto, S., Niemeijer, A., under review, Scientific Reports. Unveiling Earthquakes: Thermoluminescence Signal Resetting of a Natural Polymineral Sample in Laboratory-Produced Fault Gouge
[3] Friedrich, J., Pagonis, V., Chen, R., Kreutzer, S., and Schmidt, C.: Quartz radiofluorescence: a modelling approach, Journal of Luminescence, 186, 318–325, https://doi.org/10.1016/j.jlumin.2017.02.039, 2017a.
[4] Friedrich, J., Fasoli, M., Kreutzer, S., and Schmidt, C.: The basic principles of quartz radiofluorescence dynamics in the UV - analytical, numerical and experimental results, Journal of Luminescence, 192, 940–948, https://doi.org/10.1016/j.jlumin.2017.08.012, 2017b.
How to cite: Heydari, M., Niemeijer, A., and Kreutzer, S.: Radiofluorescence as a tool to estimate the degree of friction-induced heat caused by co-seismic slip , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5853, https://doi.org/10.5194/egusphere-egu26-5853, 2026.
During the Quaternary period the Fennoscandian ice sheet reached far into Europe on several occasions. Especially the last two ice sheet expansions, the Saalian and Weichselian, left many marks on the Danish land surface and shaped the landscape, leaving behind outwash plains, terminal moraines, tunnel valleys, and other glacial landforms. Although, there is general consensus regarding which ice advances resulted in which landscape features, most correlations have not yet been verified by absolute dating. To improve constraints on the ice cover history of the Danish area, we have carried out 10Be profiling on several outwash plains across Denmark. These outwash plains have been chosen (i) to constrain the timing of the overall ice margin retreat across Denmark, and (ii) to decipher whether the northern part of the prominent 90-degree landform (the “Main Stationary line”) belongs to the Last Glacial Maximum advance (~20.000 years ago) or a previous ice advance, such as the Kattegat advance (~30.000 years ago). Denmark is located right at the foothills of the Fennoscandian ice sheet, and we expect our results to have strong implications on the understanding of ice sheet dynamics at play during advance-retreat cycles of continental sized ice sheets, as well as to improve the understanding of the glacial history of Northern Europe. At EGU some of the preliminary results from this investigation will be presented.
10Be profiling is a technique which involves sampling sediment from several depths below the surface at a specific location. Interpretation of the 10Be concentrations can lead to age estimation of the sampled deposit, since the concentrations will depend on the cosmogenic exposure history of the sediment package. A set of samples from different depths are needed to separate the pre- and post-burial 10Be nuclide concentrations or to draw attention to 10Be irregularities throughout the profile indicating asynchronous deposition. The numerical modelling of nuclide concentrations carried out in this study serves as proof of concept and highlights the applicability of the 10Be profiling approach. Hence, alongside the preliminary results of the study, our novel MATLAB implementations for interpreting 10Be profiles will also be showcased.
How to cite: Allaart, L., Nørgaard, J., Knudsen, M. F., Andersen, L. T., Nielsen, J. B., and Larsen, N. K.: Dating DK: Cosmogenic 10Be depth profiling of glacial outwash plains in Denmark, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9469, https://doi.org/10.5194/egusphere-egu26-9469, 2026.
Basin-averaged erosion rates derived from cosmogenic nuclide concentrations are one of the most commonly used data for the study of landscape evolution histories across a wide range of tectonic and climatic regimes. Despite recent advances in global nuclide datasets and analytical techniques, methods for converting measured concentrations into denudation rates have progressed little.
Converting cosmogenic nuclide concentrations to denudation rates requires several key assumptions; however, one in particular is more difficult to assess, which is that denudation rates remain spatially and temporally constant over timescales comparable to the nuclide integration period. These assumptions rarely hold in nature, especially in mountain catchments with pronounced knickpoints propagating upstream, complicating the interpretation of a single mean concentration. Previous studies have often only evaluated how mean concentrations are affected when one or more assumptions are violated. However, minerals sampled from complex landscapes likely represent distinctly non-Gaussian populations that cannot be adequately characterized by a single mean value.
We present modelling results of cosmogenic nuclide concentration distributions in catchments experiencing spatially and temporally variable denudation rates under different tectonic and climatic forcings. Analysing concentration distributions rather than mean values alone reveals how assumption violations affect inferred denudation rates. Our model employs a detachment-limited stream power law and calculates nuclide accumulation from multiple production pathways using the Lifton-Sato-Dunai scaling scheme.
Preliminary results indicate that the presence of knickpoints does not significantly compromise the interpretation of cosmogenic nuclide concentrations except in cases with fast knickpoint retreat rates in high-relief catchments. However, we find that even moderate climatic changes (simulated by varying the erodibility constant), can yield significant errors in inferred versus real denudation rates. We propose that simple evaluations of cosmogenic nuclide distributions can enhance the reliability of denudation rate estimates in future applications.
How to cite: Grimm, L., Adams, B. A., and Fox, M.: Understanding key assumptions in cosmogenic nuclide-derived catchment-average denudation rates, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12912, https://doi.org/10.5194/egusphere-egu26-12912, 2026.
Rock glaciers are common permafrost features in mountain landscapes around the globe with a geohazard relevance sourcing large amounts of debris while also acting as aquifers storing large amounts of water, yet their long-term (i.e. centennial to millennial scale) dynamics remain poorly constrained due to limited dating efforts. Short term observations, via GPS, InSAR, UAVSAR, Lidar or feature tracking, show acceleration of flow rates of rock glaciers in all mountain regions.
We use rock glacier RG-2 in the Uinta Mountains (Utah, USA, 3 300 m asl) as a natural laboratory to test and cross-calibrate a novel luminescence-based surface dating technique: optically stimulated luminescence rock surface exposure dating (OSL RSeD). This method exploits the latent OSL or IRSL signals stored in quartz and feldspar bearing rocks and the fact that, in the upper centimeters of rock surfaces, these signals are reset (zeroed) by daylight exposure. By integrating previously CRN-dated quartzite boulders (n = 9) on RG-2 into our analysis, we (i) assess the sensitivity of parameters in the OSL bleaching-with-depth model, (ii) evaluate the model’s underlying assumptions, and (iii) interpret the resulting OSL ages.
Furthermore, we present a standardized, statistically robust workflow to normalize luminescence-depth profiles to saturation based on sequential analysis, suitable for datasets obtained by the 1D-coring-and-slicing- as well as the 2D-EMCCD-approach for various geological and archaeological dating applications.
How to cite: Sperlich, D., Munroe, J., Ramisch, A., and Meyer, M. C.: Cross-Calibration and Sensitivity Analysis of OSL Rock Surface Exposure Dating Using Cosmogenic Nuclide Ages on an Uinta Mountains Rock Glacier (Utah, USA), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14245, https://doi.org/10.5194/egusphere-egu26-14245, 2026.
Over the past few centuries, the natural flow of river water and sediment has been significantly disrupted by human activities, including land‐use change, dam and reservoir construction, and variable precipitation. Sediment accumulation in reservoirs leads to declining storage capacity, reduced water quality, and navigational challenges. While hydraulic models can characterize these issues over annual to decadal timescales, they are less effective for predicting sedimentation trajectories over decades to centuries. At these longer timescales, feedbacks between reservoir sedimentation and upstream erosion and deposition influence delta growth and sediment delivery, complicating the development of long-term sediment management strategies. To address this gap, we developed a workflow for building and calibrating open source, coupled landscape evolution models (LEMs) and delta sedimentation models (DSMs) for real-world watersheds. Here, we present preliminary results from the Chattahoochee River in the southeastern United States. The river is segmented by six major dams, each creating a reservoir and corresponding sub-catchment. We constructed a set of six LEMs using Landlab (one for each sub-catchment) and run them sequentially from upstream to downstream, using the sediment outflux from each model as input for the next. The LEMs are calibrated using cosmogenic ¹⁰Be mean catchment erosion rates, modern land-use data, and sediment trapping calculations. We then evaluated how well each model reproduced watershed sediment fluxes inferred from late 21st century suspended-sediment measurements. The DSMs are constructed using PyDeltaRCM and are driven by output sediment flux and provenance data from the LEMs. Using the pre-reservoir topography as a boundary condition, we validate the models by replicating the post-reservoir delta growth. We then use variable land use and hydraulic forcings in the LEMs to assess different future sedimentation patterns in the deltas. Our workflow can be easily applied to any reservoir with bathymetric data and can help stakeholders understand how upstream human impacts may influence a range of possible sedimentation patterns over the coming decades.
How to cite: Sheehan, C., Behn, M., Snyder, N., Cortese, L., and Dahl, T.: From Free-Flowing to Fragmented: Using Calibrated Models to Assess Impacts of Multiple Dams on Watershed Evolution, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14441, https://doi.org/10.5194/egusphere-egu26-14441, 2026.
Located at an active arc-continent collision zone subject to a tropical climate, the Taiwan mountain belt is characterized by intense tectonic activity, resulting in rapid landscape evolution. In the Western Foothills of southwestern Taiwan, geodetic data reveal rapid surface deformation during periods of low seismicity, where the upper crust is dominated by mudstone lithology. However, mapped active structures do not fully explain the observed sharp deformation gradients and uplift patterns. This discrepancy motivates an evaluation of how strain is accommodated across different timescales and whether the present-day deformation reflects persistent long-term kinematics or transient processes.
Using the ratio of meteoric 10Be to mineral-weathered 9Be measured from five river-sediment samples collected from watersheds with distinct short-term uplift rates, spatial variations in basin-scale denudation rates (Dmet) and their relationship to short-term uplift are evaluated. Although meteoric-10Be-derived denudation rates are particularly suitable for quartz-poor regions such as southwest Taiwan, the method relies on several assumptions that require validation. To assess its applicability, additional samples were collected from watersheds in the Central Range east of the study area, where in situ 10Be-derived denudation rates (Dinsitu) are available.
In the Western Foothills area, Dmet successfully captures large-basin denudation (0.77 ± 0.07 mm/yr) as the integrated signal of sub-basin denudation rates (average of 0.74 ± 0.01 mm/yr). Across two regions, Dmet values are systematically lower in the Western Foothills than in the Central Range (5.8 - 7.4 mm/yr, with an outlier of 32 mm/yr), reflecting contrasts in lithology, climate setting, and topographic relief. In the Central Range, Dinsituvalues (0.2-4.5 mm/yr) differ from Dmet, suggesting that potential grain-size differences between the two methods lead to distinct sediment transport behaviors. Nevertheless, Dmet remains informative by reproducing basin–sub-basin integration in the Western Foothills and distinguishing denudation regimes between regions.
Within the Western foothills, Dmet correlates weakly with uplift rate, slope, and relief. The normalized channel steepness index (ksn) shows an unexpectedly weak to negative relationship with Dmet. This pattern suggests that meteoric 10Be-derived denudation rates might not represent short-term surface deformation rates or are integrated over timescales that differ from those represented by geomorphic indices. This likely reflects transient surface adjustments rather than steady-state conditions. In contrast, Dmet seems to positively correlate with the extent of barren-land (badland) surfaces developed in weak mudstone formation, suggesting first-order control on basin-averaged meteoric 10Be inventories. Although badlands have been proposed to be associated with rapid erosion in this region, the correspondence between their development timescale and the integration timescale of meteoric 10Be derived denudation remains uncertain.
Future work will expand sampling across additional basins spanning a wider range of badland extent and uplift signatures to test the robustness of these relationships and refine the link between short-term deformation and longer-term surface response. Additional analyses will quantify meteoric 10Be inventories on barren land and vegetated hillslopes to evaluate differences in meteoric 10Be retention across contrasting hillslope environments, thereby refining the applicability and sensitivity of the methods to hillslope transport processes.
How to cite: Nguyen, N.-T., Siame, L., Le Béon, M., Léanni, L., Pathier, E., and Team, A.: Landscape Response to Rapid Uplift in Southwestern Taiwan: Insights from Denudation Rates Measurement from Cosmogenic 10Be (Meteoric)/9Be Ratios and Morphometric Indices, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15516, https://doi.org/10.5194/egusphere-egu26-15516, 2026.
High-definition digital elevation models (DEMs) from airborne light detection and ranging (LiDAR) are very powerful tools in detecting unknown tectonic-geomorphic features and quantifying cumulative slip from repeated faulting events. The faulted geomorphic features, however, need to be somehow dated to convert the slip to long-term slip rate, and this task still remains as a challenging part of many tectonic geomorphic and paleoseismic studies. The dating is particularly difficult in mountainous and densely vegetated regions, where we are most benefitted from LiDAR DEMs but most often confront challenges in finding datable organic materials in high-energy gravelly deposits. Here we attempted to date left-laterally faulted fluvial terrace surfaces discovered along the Nobi active fault system (NAFS) in the Etsumi Mountains, central Japan, by using a terrestrial cosmogenic nuclide Be-10. In this region, terrace surfaces are covered with thin aeolian loess deposits of <1 m thick, with generally thinner loess cover on younger and lower surfaces. We employed the depth-profile method to simultaneously determine the age and inherited nuclide concentration, incorporating the effect of loess deposition after terrace abandonment. Exploratory pits for depth profiling were excavated at two sites along the NAFS; the Nukumi-Shiratani site on the low terrace surface along the Nukumi fault and the Nogo site on the middle terrace surface along the Neodani fault. Our results show the terrace abandonment ages that are consistent with the generally accepted terrace-formation and incision history modulated by global climate changes (MIS 2 and MIS 4 for the low and middle terrace surfaces, respectively) and also with crypto tephras identified in the loess deposits. In turn, the long-term left-lateral slip rate for the Nukumi fault was first determined whereas that for the Neodani fault proved to be substantially larger than estimates from previous studies.
How to cite: Kaneda, H., Matsushi, Y., Ogura, Y., Ohta, R., and Matsuzaki, H.: Dating faulted terrace surfaces with thin aeolian loess cover by using terrestrial Be-10 depth profiles: an attempt along the Nobi active fault system, central Japan, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16139, https://doi.org/10.5194/egusphere-egu26-16139, 2026.
The observation that topography trends with snowline altitude despite large differences in tectonic uplift in various locations provides the foundation of the glacial buzz-saw hypothesis. However, despite numerous modelling studies, very few quantitative data are available that document the timing or rate of glacial topography formation. Consequently, challenges remain to explain why some localities (e.g. Alaska, southern Andes) seem to escape the glacial buzz-saw. This data gap is driven by the difficulty in constraining rates of glacial erosion over kyr-Myr timescales.
Here, we use a novel thermochronometry technique, based on the Electron Spin Resonance (ESR) of quartz minerals, to constrain the timing of cirque basin formation adjacent to the Rhône valley, Switzerland. The Fully basin, near the town of Sion, sits above the ~1.5 km deep glacial Rhône valley, and is thought to have been incised by ~400 m during the Quaternary. Samples were collected in a transect across the basin, and complement samples previously investigated using ESR-thermochronometry from the Rhône valley (Wen et al., 2024).
Forward modelling using a modified version of Pecube together with the kinetic parameters of existing ESR samples from the area (Wen et al., 2024) shows that ESR-thermochronometry data should be able to constrain the timing of cirque basin incision. This will provide the first dates and rates of glacial buzz-saw activity and will be contrasted with the timing of Rhône valley incision.
How to cite: King, G., Bernard, M., Wen, X., Cox, S., Dave, A., and Schmidt, C.: Putting rates on the buzz-saw? Constraining the timing and rate of cirque valley incision, Rhône valley, Switzerland., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16746, https://doi.org/10.5194/egusphere-egu26-16746, 2026.
The southern Central Andes forearc preserves extensive low-relief wave-cut platforms and fluvial terraces that record long-term margin uplift, yet the timing and driving mechanisms are still debated. Here we present eleven new in situ ¹⁰Be exposure ages from high fluvial terraces and four ages from a lower terrace, combined with geomorphic analyses across eight adjacent catchments, to reassess the age and tectonic significance of the degradational surfaces (pediplain) present between 29.5 and 32.5°S. Erosion-corrected exposure ages indicate that the high terrace formed during the Early Pleistocene, while a lower terrace records incision at Middle Pleistocene. Longitudinal terrace–channel profiles reveal systematically increasing relief toward the coast that terminates near the surface projection of the 50–60 km slab-depth contour, coincident with the downdip limit of megathrust domain-C earthquakes. This spatial relationship supports a regionally coherent uplift signal produced by the cumulative effect of deep coseismic deformation. In peninsular settings, notably the Altos de Talinay, this long-wavelength signal is overprinted by short-wavelength uplift consistent with localized underplating. Our results demonstrate that the high fluvial terraces and the shore wave-cut platform constitute a single, regionally continuous geomorphic marker recording an Early Pleistocene forearc uplift phase extending from ~16° to 42°S. This orogen-scale emergence implies a subtle but widespread change in subduction dynamics during the last Early Pleistocene, the causes of which are not clearly understood.
How to cite: Gianni, C. R., Ballato, P., Schildgen, T., Gianni, G., Wittmann, H., Melnick, D., and Faccenna, C.: Geomorphic imprint of an Early Pleistocene uplift phase of the Andean forearc and its underlying mechanisms, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22489, https://doi.org/10.5194/egusphere-egu26-22489, 2026.
