Glaciers can carve deep valleys and generate steep mountain peaks, and glacial erosion has long been recognized as a relief production process that creates some of the Earth's most picturesque topography. However, previous work suggests that, in some cases, glacial erosion may act as a “buzzsaw” and reduce mountain relief. This occurs because glaciers tend to concentrate erosion at elevations above the snowline, causing a decrease in relief between the snowline and mountain ridgelines. The scenarios under which glaciers enhance versus inhibit relief remain poorly understood. In this study, we test the evolution of relief at a local scale (approximately 2 to 5 km) under various tectonic and climatic conditions using numerical landscape evolution models. The model solves glacier flow with high-order ice physics and simulates glacial erosion as a function of glacier sliding velocity. Results indicate that relief reduction occurs exclusively in regions with slow glacier sliding velocities, predominantly at or below the glacier equilibrium line altitudes (ELAs). To validate these findings, we evaluated the relief evolution in the European Alps. The diverse range of climates and elevations caused varying durations of ice cover during the Quaternary in the Alps, making it possible to substitute space for time across the Alps to understand the relief evolution. We examined the change of relief in relation to reconstructed ice cover duration. Our analysis demonstrates that in regions with slow simulated glacier sliding velocities during the last glaciation, relief decreases with increasing ice cover duration, indicating that slow-flowing glaciers progressively reduce relief. Moreover, these areas exhibit a clustering of elevations around 1500–2000 m, aligning with the past ELA in the Alps. These findings are consistent with our numerical simulation results, and suggest that slow-flowing glaciers at or below the ELA act as agents of relief reduction.
How to cite: Lai, J., Huppert, K., and Ehlers, T. A.: Controls on relief development in glacial landscapes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12386, https://doi.org/10.5194/egusphere-egu25-12386, 2025.
Recovering the patterns of glacial erosion over time is key to understanding feedbacks between climate and tectonic processes. Glacial erosion rates have been shown to systematically increase worldwide toward the present since the late Cenozoic, a behavior interpreted as the response of glaciers to a cooling and increasingly variable climate. However, the validity of this signal has been questioned, and suggested to be affected by the incompleteness of the sedimentary record, which can introduce a time dependent bias in the time averaged rates. In this study, we present new glacial erosion rates estimated from sediment accumulations in Lago Argentino, Patagonia, a proglacial basin with a nearly complete preserved sedimentary record. The erosion rates are estimated through the past 20,000 years and averaged over time intervals ranging from subdecadal to millennial, allowing us to explore erosion rate variability through time and within a glacial cycle. The data show that erosion rates have varied substantially, from 0.43 ± 0.12 to 82.38 ± 17.58 mm/yr, with no systematic increase (or decrease) through time. Rather, erosion occurs during discrete, intense events separated by times of quiescence. In addition, we find that glacial erosion rates have comparable magnitudes when averaged over similar time intervals. Our data show a power‐law increase in glacial erosion rates with decreasing averaging time interval, consistent with other observations globally. Given our observed intermittent character of glacial erosion, we attribute this increase to a time averaging bias, rather than to an escalation in magnitude of erosional pulses toward the present.
How to cite: Magnani, M. B. and Fedotova, A.: Glacial Erosion Rates Since the Last Glacial Maximum for the Former Argentino Glacier and Present‐Day Upsala Glacier, Patagonia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3350, https://doi.org/10.5194/egusphere-egu25-3350, 2025.
Crustal thickening associated with orogenic growth elevates topography, causing the orographic enhancement of precipitation, which in turn facilitates local erosion and possibly intensifies the localization of deformation. The orographic climate-tectonics-erosion feedback exists in small orogens such as the Southern Alps of New Zealand and Olympic Mountains of Washington State, USA, and may be even stronger under some circumstances in active orogens on the margins of large, high-elevation plateaus such as the Himalayas, the Tibetan Plateau, and the Central Andes. How these three processes—deformation, precipitation, and erosion—coordinate during orogenic growth remains unknown. Here, we present a new numerical model where tectonics, surface processes, and orographic precipitation are tightly coupled, and explore the impact on low, intermediate, and high erodibility orogens. We show that, for the intermediate erosion models, rock uplift rates and precipitation rates correlate well with erosion rates for the formation of orogenic plateaus with high correlation coefficients of ~0.9 between rock uplift and erosion rates, and ~0.8 between precipitation and erosion rates. We propose that three processes (deformation, precipitation, and erosion) take place successively as a consequence of the lateral orogenic growth, and demonstrate a cyclicity of correlation evolution among uplift, precipitation, and erosion rates through the development of new faults propagating outward. These results shed new insights into the relative tectonic or climatic control on erosion in active orogens (e.g., the Himalayas, the Central Andes, and the Southern Alps of New Zealand), and provide a plausible explanation for several conflicting data and interpretations in the Himalayas, which we propose are due to the youthful, mature, or old stage of faults and different locations relative to the old faults. Studies using similar approaches with more detailed geological parameters could shed more insights into the growth of mountain belts co-evolving with spatiotemporally tectonic and climate change, and help more quantitatively establish links between tectonics, climate, erosion, topography, and biodiversity.
How to cite: Yuan, X., Li, Y., Brune, S., Li, K., Pons, M., and Wolf, S.: How do deformation, orographic precipitation, and erosion coordinate during orogenic growth?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8375, https://doi.org/10.5194/egusphere-egu25-8375, 2025.
The Kyrgyz Range, located on the northwestern edge of the Tien Shan, provides a unique opportunity to study the interplay between tectonic processes and climatic forces in shaping mountain landscapes. The apatite (U-Th-Sm)/He (AHe) thermochronometric system, sensitive to low-temperature (<100 °C) cooling histories, has the potential to detect million-year timescale changes in exhumation rates in glaciated regions. Previous studies in the Kyrgyz Range have identified increased exhumation rates over the last ~3 Ma (Bullen et al., 2003; Sobel et al., 2006).
In this study, we present seven new AHe ages from the Ala Archa valley, ranging from 3.3 ± 1.0 Ma to 7.5 ± 1.4 Ma. Samples were collected from granite outcrops along an elevation profile spanning 1,850 m (1792–3634 m), including the main trunk and a tributary valley with clear glacial imprints. 1D modeling of these ages reveal: (1) an onset of cooling at ~12–10 Ma, consistent with published work and interpreted as the start of exhumation in the Kyrgyz Range; and (2) a rapid increase in cooling rates between 0 and 3 Ma, recorded in the lower elevation samples (1792–2240 m).
Using 3D thermal-kinematic modeling with Pecube, we explored scenarios of topographic and tectonic evolution to explain these cooling ages. Our modeling shows that topographic evolution, specifically valley incision, can produce rapid and recent cooling ages even when rock-uplift rates are low (<0.5 km/Ma). Modeling further suggests that the onset of Pleistocene glaciations likely drove a phase of rapid valley incision in the Kyrgyz Range, emphasizing the impact of climatic forcing on exhumation.
Field constraints and reconstructed sediment volumes from the adjacent Chu Basin indicate a change in sedimentary dynamics between 4 and 2 Ma, supporting this scenario. These findings emphasize the critical role of glaciation in shaping the Kyrgyz Range, with glacial erosion contributing substantially to valley incision and exhumation rates.
This study underscores the importance of integrating thermochronology with topographic and thermal modeling to disentangle tectonic and climatic influences on mountain range evolution. Without accounting for changes in topography, variations in exhumation rates might be incorrectly attributed solely to tectonic uplift, potentially overlooking significant climatic impacts.
How to cite: Mariotti, A., Schildgen, T., Sobel, E. R., Gong, L., van der Beek, P., Bernard, M., Wapenhans, I., and Glodny, J.: Landscape Evolution of the Kyrgyz Range (Tien Shan): Deciphering Tectonic and Climate Inputs, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13803, https://doi.org/10.5194/egusphere-egu25-13803, 2025.
Topography in tectonically active regions can provide a record of the history of uplift and, while less studied, horizontal motions as well. Stream channel geometry, especially, has been shown to be sensitive to tectonically driven rock displacement, which is often reflected in spatial variations of the normalized channel steepness index (Ksn). Numerical landscape evolution models can be used to model the effects of tectonics on the topography. This raises the possibility of using landscape evolution models to solve an inverse problem, in which rates and spatial patterns of uplift and advection are quantified based on observed features of a landscape. Similar methods have been developed previously, but they have mostly been focused on uplift only and/or on the inversion of one-dimensional, longitudinal stream profiles rather than two-dimensional landscapes. In this study, we introduce a new approach to invert for both vertical and horizontal kinematics from present-day topography. We use as data the average elevation and average Ksn calculated in a moving window along a profile across-strike of the orogen, and we search for landscape evolution models that can reproduce these features. To fit models to data we use ensemble Kalman inversion: an efficient, ensemble-based, gradient-free data inversion method that can handle large numbers of free parameters and can quantify uncertainty in the results. We first demonstrate our method using a synthetic model, inspired by the Eastern Alps, and we then apply it to a real-world profile, the TRANSALP geophysical transect. With the synthetic model, we show that our method can accurately recover magnitudes and changes in uplift and advection rates in both space and time. In addition, we test synthetic models with a short-time, low-amplitude (0.1-1 mm/yr), long-wavelength surface uplift superimposed on fault-related kinematics, which represents the effects of mantle processes or isostatic responses. We find that this uplift pulse can be identified if the event occurred within the past ~5 Ma but becomes increasingly difficult to detect as it is moved back in time, although the specific time limits will likely vary with the parameters of the erosion model. Applying the method to the real-world data, we see evidence of a short-wavelength pulse of uplift in the Tauern region, approximately consistent in time and space with other evidence for the exhumation of the Tauern Window. We do not detect evidence of a hypothesized longer wavelength surface uplift, implying that if any such event occurred it must have been sufficiently far back in time that its topographic record has been erased. In summary, our work provides a new method for interpreting tectonics from topography and demonstrates that it can constrain location and magnitude of rock displacement.
How to cite: Oakley, D. and Eizenhöfer, P.: Inversion of Landscape Features for Deformation Patterns using Landscape Evolution Models: An Example from the Eastern Alps, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9953, https://doi.org/10.5194/egusphere-egu25-9953, 2025.
The impact of Quaternary glaciation on the exhumation of the western European Alps remains unclear due to a lack of geochronological methods that cover the timespan of 103-106 years. In this study, we combine new ultra-low temperature (<100°C) electron spin resonance (ESR) thermochronometry data, from the Rhône valley (Sion and Visp, Switzerland) with existing low-temperature thermochronometry data (apatite fission track and apatite (U-TH-Sm/He)) from the surrounding area to constrain the exhumation history from the late Miocene to the Quaternary. Ten samples collected near the city of Sion give ESR ages ranging from 0.21 to 0.67 Myr and five samples collected near the city of Visp give ESR ages ranging from 0.67 to 2.04 Myr.
We explored different tectono-geomorphic scenarios using a 3D thermo-kinematic model, Pecube, to estimate recent changes in tectonic uplift and relief of the Rhône valley. Although modelling results from Sion and Visp are slightly offset temporally, they both exhibit at least three main stages of exhumation in the last 15 Myr. A phase of rapid exhumation (~1 km/Myr for Sion and 2 km/Myr for Visp) that started around 5.2 Myr for the Sion area and 7.9 Myr for the Visp area, was followed by a second phase of reduced exhumation (< 0.1 km/Myr). The ESR data provides new constraints on relief evolution and supports rapid valley incision of up to 1.5 km at around 0.6 Myr for both sites. This phase of rapid valley deepening is likely associated with glacial carving of the Rhône since the mid-Pleistocene transition.
The timing of the exhumation phases in the late Neogene are consistent with previous studies, whilst the ESR data offers more precise constraint of the latest phase of exhumation (<1 Myr). Our results demonstrate that quartz ESR thermochronometry is a reliable tool for constraining Quaternary landscape dynamics that offers high resolution over sub-Myr timescales.
How to cite: Wen, X., Bernard, M., King, G., Braun, J., Kranz-Bartz, M., and Schmidt, C.: Exhumation of the western European Alps (Switzerland) using ultra-low temperature and classical thermochronometry and numerical modeling (Pecube) , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16579, https://doi.org/10.5194/egusphere-egu25-16579, 2025.
Despite its complexity, the Neogene/Quaternary evolution of Central Europe’s drainage system is well constrained by a diverse set of empirical data (e.g., provenance, geochronology, biostratigraphy). However, the underlying causes of major changes in drainage patterns remain debated. For example, it is still unclear which factors and mechanisms (e.g., large-scale uplift patterns) led to flow reversals of the major eastern tributaries of the Rhine since the Miocene. Commonly, it is stated that the reorganizations of rivers were caused by the opening of the Upper Rhine Graben driven by an extensional tectonic regime since the Eocene and the associated lowering of the base level. Recent studies often attribute relief changes due to the late phases of Alpine tectonics and the last uplift of the Alb, although the reason and dimensions usually remains unclear. We hypothesize that the uplift pattern of Miocene folding of the lithosphere, as described in tectonically oriented journals, could be the reason for the river reversals. We also assume that the reversals were probably not caused by river beheading alone, but mainly by river capture.
To test our hypothesis, we use our newly developed landscape evolution model TTLEM-3D in addition to analysis of many regional studies. The model can be used with a pure detachment-limited as well as with a shared-stream power model and uses one or more layers. The results of a first sensitive analysis, which involves a simplified simulation of the main tectonic forcing since the Cretaceous, indicate that the assumed uplift pattern of the lithospheric folding could have led to a flow reversal. From the rate of change of the catchment size, it can be estimated that river capture, rather than river beheading, could be the main drainage rearrangement mechanism here. In addition, the timing and the hypothesized pattern of uplift and lowering of the lithosphere are in good agreement with the reversal of the Main and Neckar rivers observed in regional studies.
The findings suggest that a baseline drop alone is insufficient and that additional uplift impulses are required. Our simplified numerical model supports the idea of folding of the lithosphere but does not rule out other tectonic and geological processes. The overlapping of different mechanisms makes deciphering this area difficult. We try to combine geomorphological observations with tectonic studies. This study challenges established theories and attempts to contribute to a better understanding of the geomorphological history of Central Europe. It seeks to unravel the complex interactions between tectonic, landscape and fluvial dynamic processes.
How to cite: Rau, M., Schwanghart, W., and Krautblatter, M.: A landscape evolution model deciphering the influence of large-scale uplift patterns on the Central European drainage system, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19520, https://doi.org/10.5194/egusphere-egu25-19520, 2025.
Escarpments are preserved rift shoulders formed during continental rifting, such as the Red-Sea escarpment or those created during the breakup of Gondwana. Morphologically, escarpments function as highly asymmetrical water divides, separating steep, sea-draining rivers from low-gradient rivers draining the interior plateau. The evolution of an escarpment landscape is characterized by horizontal retreat driven by differential erosion rates across the water divide, even in tectonically inactive settings.
The horizontal migration of escarpments at rifted margins challenges conventional intuitions based primarily on two key observations:
- Observed denudation and rock exhumation rates, typically below 50 m/Ma over geological scales, with escarpment basins exhibiting higher rates than plateau basins;
- The “kinked” profile morphology of escarpment-draining rivers, where morphological knickzones are universally identifiable.
These observations are often interpreted in terms of temporal or spatial variations in uplift rates, attributed to tectonic rejuvenation, mantle dynamics-driven uplift, or the influence of precipitation and lithology.
In this study, I present insights derived from numerical model simulations of escarpment systems, demonstrating that the escarpment retreat can be conceptualized as a process of topographic advection. In a topographic advection system at steady state, rock erosion rates balance the combined effects of vertical rock uplift and the product of the directional topographic slope and horizontal rock advection velocity, relative to the topographic system’s boundaries (i.e. base level or water divide). In such settings, river morphologies adjust to the horizontal advection velocity by modifying their steepness to align with the erosion rate, maintaining a consistent relationship between steepness and erosion dynamics. The origin of the advection velocity may arise from tectonic activity or laterally moving boundaries, or any mechanism that generates horizontal rock velocities relative to the boundaries.
In an escarpment system, the advection velocity arises from the steady migration of the water divide, which expands the escarpment area while shrinking the plateau area, and create rock velocity relative to the divide. Although the observed erosion rates in tectonically inactive escarpments appear “slow”, they reflect the product of the topographic slope and a “fast” divide migration rate. The divide migration rate is typically one or two magnitude higher than the measured erosion rate, as the topographic slope is naturally less than one. This relationship applies to both escarpment basins and plateau basins. Morphologically, plateau basins exhibit lower gradients than escarpment basins, resulting in lower erosion rates on the plateau side, as the divide migration velocity remains constant. In escarpment-draining rivers, steep upper reaches originate from the major water divide, maintaining distinct morphologies consistent with the “top-down” dynamics of constant divide migration under constant base levels.
How to cite: Wang, Y.: Escarpment Retreat- Intuitions, Mechanisms, and Rates, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8641, https://doi.org/10.5194/egusphere-egu25-8641, 2025.
Plate tectonics and mantle dynamics drove the continental collision and topographic evolution in the Eastern Mediterranean – Tethyan realm leading to the closure of the Tethys Seaway, which once linked the Atlantic and Indo-Pacific oceans. The closure led to reorganizations in ocean circulation, diversification and migration of marine and terrestrial species, and climatic changes. In this Review, we evaluate the causes and consequences of closing the Tethys Seaway and quantify the processes generating topography in this region for the last 66 million years. We discuss how the arrival of the Afar Plume and northward mantle flow influenced dynamic topography and caused regional uplift and volcanic activity. Mantle convection ultimately established a permanent land bridge between Africa and Asia in the Miocene, enabling one of the greatest faunal interchanges of the Cenozoic.
How to cite: Faccenna, C., Straume, E., Becker, T., Steinberger, B., Licht, A., Sembroni, A., Gvirtzman, Z., and Ballato, P.: Dynamic topography and landbridge formation during the Tethyan closure, in the Eastern Mediterranean : implication for biodiversity, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13565, https://doi.org/10.5194/egusphere-egu25-13565, 2025.
Tropical hotspot volcanic islands are exceptional laboratories for understanding climate-landscape interactions. Réunion Island, in the southern Indian Ocean, is particularly interesting because it has one of the largest rainfall gradients in the world: from 0.5 to 11 m/yr over a 50 km distance. It experiences frequent cyclones, such as the January 15th, 2024 cyclone Belal that produced from ~0.1 to ~1 m of rainfall in 24 hours. Réunion is composed of two shield volcanoes: Piton des Neiges (3070 m, dormant) and Piton de la Fournaise (2632 m, active). Here, we focus on long-term (Myr) and short-term (<yr) erosion of Réunion Island.
Long-term basin-averaged erosion rates based on excavated lava volumes of 29 catchments located on both the leeward and windward side of the island range from ~10-3 to ~10 mm/yr. Erosion rates for basins eroding < ~1 mm/yr show a positive relationship with mean annual precipitation. They also have a negative relationship with the duration of erosion, i.e. the age of the incised volcanic surface, which we consider as a proxy for post-eruption basin aging. Fluvial incision parameters recovered from numerical modelling of the stream power law show a positive trend with mean annual cyclonic rainfall.
To disentangle the dual effect of climate and post-eruption surface aging on erosion, we perform a series of correlation analyses between mean rainfall and rainfall variability, river discharge, catchment morphometrics, and time elapsed since the latest eruptions for 136 basins. We find that Hack’s law exponent (the relationship between basin area and river length), drainage density, and large basins width and hypsometry integral follow a temporal trend (mostly on Piton des Neiges), which confirms published work on stratovolcanoes. Discharge variability has no apparent relationships with basin geometry and erosion. Interestingly, Piton des Neiges and Piton de la Fournaise volcanoes have different main climate erosion drivers: the first one seems to be more influenced by mean annual precipitation, and the second by precipitation variability.
To test whether the effect of rainfall variability and mean annual rainfall on erosion, which we observe at long timescales, can be detected at short timescales, we conducted three field surveys of river channels in October 2023, February 2024, and October 2024, i.e. before and after cyclone Belal. We used photogrammetry to survey the river sediments and to extract 3D shapes and grain size distributions of channel bedload (pebble, cobble, boulder) from point clouds. In addition, we assessed local channel modifications, including sedimentary deposition and excavation, terrace undercutting, and movement of large boulders. These data will provide erosion thresholds for fluvial incision, and will allow comparative temporal and spatial analysis of grain sizes distribution. In the future, more investigation will be needed on denudation at thousand-year timescales to bridge the gap between our short- and long-term studies.
How to cite: Gourbet, L., O’Hara, D., Jocham, F., Gallen, S. F., Famin, V., Guerit, L., Ramanitra, M. O., Gayer, E., and Michon, L.: Impact of climate and volcanism age on landscape evolution of oceanic islands, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8546, https://doi.org/10.5194/egusphere-egu25-8546, 2025.
The Northern Apennines are an active orogenic wedge formed by subduction and rollback of the Adriatic plate over the last 30 Ma, where horizontal shortening and topographic advection lead to river capture and drainage divide migration. The orogen exhibits topographic asymmetry across the main drainage divide: the Adriatic side is steeper than the Ligurian side, suggesting drainage divide migration towards the Adriatic, opposite the direction of the horizontal tectonic advection of topography. In this study, we present new catchment-averaged denudation rates from major drainage basins in the Northern Apennines derived from cosmogenic 10Be concentrations, supplementing published data, in order to quantify the erosional fluxes from the orogen and compare the pattern of modern denudation rates with the topographic asymmetry. Catchment-averaged denudation rates and horizontal velocities increase from west to east throughout the study area; rates on the steeper Ligurian side of the main drainage divide are lower than those on the gentler Adriatic side. We reconcile these data with a kinematic model of slab rollback, where the erosional flux is described as a vector with horizontal and vertical components. The model predicts that the topography and denudation rates can be sustained by horizontal motion that dominates the Ligurian side, while both horizontal motion and vertical uplift are required on the Adriatic side. Our results help us assess how drainage divides evolve and provide insights into tectonically driven drainage reorganization, which may have important biodiversity implications, e.g., influencing the intraspecific genetic diversity of endemic riverine fish.
How to cite: Vance, G., Erlanger, E., Clementucci, R., Wang, Y., Haghipour, N., Christl, M., Gautschi, P., Picotti, V., and Willlett, S. D.: Catchment-averaged denudation rates derived from cosmogenic 10Be in the Northern Apennines (Italy) and implications for landscape dynamics , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9044, https://doi.org/10.5194/egusphere-egu25-9044, 2025.
Rivers are primary agents of erosion, shaping valleys, drainage divides, and controlling the larger-scale landscape dynamics. Mass wasting and ‘diffusive’ processes on adjacent hillslopes also impact landscape form and dynamics, shaping hilltops, and hillsides, and adding sediment into channels. Extreme environments, such as hyper-arid deserts, offer a unique natural experiment to isolate landscape modification without continuous fluvial processes. Here, we explore numerical simulations of a landscape that experiences oscillatory fluvial activity, continuous vertical uplift, hillslope processes, and strike-slip faulting, inspired by a natural landscape in the Atacama Desert. Because strike-slip faults are structures known for diverting rivers and generating a dynamic response on hillslopes, we explore the landscape response to this perturbation when the climate is dry and the rivers are ephemeral. Our model simulates river incision, sediment deposition, hillslope diffusion, weathering, and faulting. The experiments bring light to three main findings: (1) under the absence of continuous fluvial incision, offset channels are less sinuous than offset channels that experience continuous fluvial erosion; (2) during long dry periods, hillslope sediment supply helps to decrease valley height and controls channel bed geometry; and (3) long river profiles in the oscillatory fluvial scenario preserve knickpoints for longer compared to those under continuous fluvial erosion that can readjust despite the cycle of strike-slip faulting. This work has implications for our understanding of sediment-dominated environments, strike-slip fault settings, and landscapes that continue evolving under the absence of steady fluvial erosion, and it highlights the importance of hillslope processes in dry climates, on Earth and other planets.
How to cite: Aranguiz Rago, T., Duvall, A., Tucker, G., and Campforts, B.: When rivers turn off but hillslopes and faults do not: oscillatory fluvial activity under strike-slip faulting, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9392, https://doi.org/10.5194/egusphere-egu25-9392, 2025.
Mountain landscapes exhibit significant variability in their topographic properties, glacial cover, climate conditions, and the geological characteristics of the underlying bedrock, all of which contribute to the diversity of potential sediment sources. While it has been recognized that such variability is largely scale-dependent – meaning the spread of morphometric parameters, for instance, decreases as the size of the upstream drainage basin increases – there is limited research on this topic. However, understanding this dependency is crucial for determining the mechanisms driving catchment-wide erosion and identifying the origin of detrital material in the channel network.
Here we focus on the 4300 km2-large Alpine Rhine basin located in the European Alps of Switzerland. The Alpine Rhine basin itself is made up of >2000 tributary basins, which we delineated using the stream junctions as outlet points. For each of these tributary basins as well as for the progressively larger drainage basins farther downstream, we calculated a set of parameters including, but not limited to: mean hillslope angles, mean normalized steepness and concavity values of channels, glacial cover, annual precipitation rates and temperature ranges, and lithology. To explore the physical records of this variability, we determined the pattern of catchment-averaged denudation rates derived from concentrations of in-situ cosmogenic 10Be in detrital quartz at 49 sites.
The results reveal that the mean hillslope angles vary from c. 16° to 36° for basins smaller than 100 km2. For larger basins, the upstream hillslope angles converge to a mean value of 27±3° (2-sigma standard deviation). The same pattern is also visible for other morphometric variables characterizing the shape of channels (e.g., concavity and normalized steepness values) and for parameters characterizing the hydroclimate and lithology of the basin. Similarly, a scale-dependent pattern is also visible for the 10Be-based denudation rates where a large variability spanning between <0.3 mm/yr to >2 mm/yr for basins <100 km2 converges to a basin-averaged mean of c. 0.8 mm/yr at the downstream end of the Alpine Rhine. Mapping shows that the high rates are due to stochastic sediment input by landsliding, debris flows or glacial melt, while the low rates occur in basins where overland flow erosion dominates. This basin size, which is <100 km2 for the Alpine Rhine, can thus be considered as a threshold value where detrital signals are produced and still well mixed, while for larger basins such primary signals may be diluted. This threshold is crucial as it provides constraints for both optimizing a sampling strategy for cosmogenic nuclides analysis and interpretation of the corresponding results.
How to cite: Garipova, S., Mair, D., Singh, V., Shiroya, K., Matsuzaki, H., Akçar, N., Christl, M., and Schlunegger, F.: Scale dependency of the landscape’s morphometry in the Alpine Rhine, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10705, https://doi.org/10.5194/egusphere-egu25-10705, 2025.
The Vosges massif, a mid-altitude mountain range in northeast France, stretches 250 km north of the Alps, displaying significant north-south and east-west topographic, geological, and geomorphological gradients. Despite the region's low deformation rates and moderate seismicity, dominated by strike-slip mechanisms, the Vosges still maintain significant topographic relief, raising questions about the forces sustaining the massif’s topography.
The evolution of drainage divides offers insights into the interplay of tectonic, erosional, and climatic processes shaping mountain landscapes. This study investigates the dynamics of the main drainage divide of the Vosges through a comprehensive analysis integrating morphometric indices, denudation rates derived from cosmogenic nuclide concentrations (10Be and 26Al isotopes) in small catchments, and hilltop curvature as a proxy for denudation rates. By analysing small-scale, second-order basins near the divide, we reduce complexities associated with sediment routing, lithological heterogeneities, and large-scale geomorphic integration. In addition, by using a calibrated relationship between hilltop curvature and the local denudation rates, we provide a region-wide quantification of the divide migration rate unravelling the processes driving its ongoing dynamics.
The results reveal that the main drainage divide is systematically migrating westward, away from the Rhine River valley. In the southern Vosges, transient geomorphic processes, including knickpoints and episodic river captures, drive rapid adjustments intertwined with a background of slow and gradual divide migration. Conversely, the northern Vosges exhibit lower relief and subdued topographic gradients, where weaker erosional contrasts result in negligible divide mobility despite comparable cosmogenic nuclide-derived denudation rates.
These findings emphasize that even in low-deformation settings, subtle and transient processes can maintain relief and reconfigure drainage networks. Mid-altitude, slowly deforming landscapes like the Vosges are not necessarily stable; instead, they continue to evolve through a balance of gradual erosional processes and episodic drainage readjustments, sustaining relief over geological timescales.
How to cite: Mathieux, B., van der Woerd, J., Steer, P., Carcaillet, J., and Chabaux, F.: Unravelling the drainage divide migration of a slow deforming mountain range: Insights from morphometry, hilltop curvature and cosmogenic nuclides in the Vosges Mountains (NE France), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12046, https://doi.org/10.5194/egusphere-egu25-12046, 2025.
The climatic and tectonic history of the Piedmont zone of the Apennines has been reviewed by leveraging the depositional records of the Tenna, Aso and Tesino Rivers, located in the Marche region of Central Italy. The westernmost part of this region has been subjected to uplift since the Middle-Late Pliocene, resulting in the emergence of the area, due to the propagation of the compressional front of the Apennines. Several studies, predominantly based on methodologies that rely on the sedimentological record, have obtained for the Marche Piedmont Zone uplift rates ranging from 0.2 to 0.7 mm yr⁻¹. The low-rate uplift activity has left as evidence different features, including also well-developed staircases of fluvial terraces of the fill type. The formation of this terrace type is strongly influenced by climate variations. From this perspective, fluvial terraces are recognized as impact-oriented indicators of middle-long term climatic oscillations, contributing to the aims of the extended partnership RETURN (multi-Risk sciEnce for resilienT commUnities undeR a changiNg climate). Indeed, the Italian National Recovery and Resilience Plan (PNRR), funded by Next Generation EU, aims to consolidate research on environmental, natural, and anthropogenic risks connected to climate change.
By extracting chronological and sedimentological data from the fill terrace deposits of the three selected rivers it was possible to assess and delineate the dynamics associated with the landscape evolution of the study area. Luminescence dating techniques were applied on the deposits to determine the timing of sedimentation of the fluvial terraces, yielding a total of eleven ages, that extend back to the Middle Pleistocene. We preliminary conducted a semi-automatic extraction of the terrace treads from high-resolution LiDAR DTMs of the river valleys: from these, the topographic slope and roughness were calculated and applied for the extraction of smooth sub-planar surfaces corresponding to the treads of the terraces. This process was essential for classifying the terraces into different levels based on their height above the channel thalweg, thereby contributing, together with on-field characterization of the deposits, to the creation of an updated map of the fluvial terraces, followed by the analysis of their altimetric and along-valley distribution.
The obtained new data has been reviewed both at the level of the individual rivers and in relation to Late Pleistocene - Holocene data already available from terrace deposits of other rivers of the Marche region. This enabled the analysis in parallel of the emplacement of different terrace levels both inside each valley and between adjacent ones, allowing the extraction of new uplift rates relative to the Piedmont zone of the Apennines and the recognition of differential uplift acting in correspondence to the studied area. Furthermore, owing to the overall expansion of the chronological record relative to the terrace deposits, it was possible to evaluate the correlation between the timing of fluvial deposition and the alternation between glacial and interglacial stages characteristic of the Quaternary, determining that sedimentation on the valley floor is strongly influenced by the effects of glacial stages on vegetation and sediment stabilization along the slopes, bringing to fluvial sedimentation.
How to cite: Ruscitto, V., Delchiaro, M., Della Seta, M., Gribenski, N., Iacobucci, G., Piacentini, D., Richard, M., and Troiani, F.: The interaction of climate and tectonics since the Middle Pleistocene in the Marche Piedmont Zone of the Apennines: new geochronological data from the fluvial record., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13366, https://doi.org/10.5194/egusphere-egu25-13366, 2025.
Terraces have been studied across the globe to reconstruct past tectonic and climatic change. Himalayan rivers have some of the highest sediment loads globally, transporting a total of c. 103 Mt of sediment annually to ocean basins. Significant quantities of alluvial sediment in the Himalaya are stored in fill terraces, which have been identified across the range. These terraces record past tectonic and climatic events such as earthquakes, glacial lake outburst floods, landslides, changes in water and sediment flux during glacial-interglacial cycles, or rapid tectonic incision into valley deposits from an increase in rock uplift. Our knowledge of the geographical extent of Himalayan terraces is currently incomplete and often focused on reaches of individual rivers. This is partly a consequence of low preservation due to erosional processes within a rapidly uplifting mountain range, or past limitations in field access and remote sensing techniques.
Using an automatic method for identifying river floodplains and terraces, we identify terraces along every major river within the Gandaki catchment of central western Nepal. We explore the spatial pattern and extent of terraces along each river within the catchment. We link terrace deposition and preservation to tectonic drivers by analysing the relationship between terrace exposures and channel steepness and major structural boundaries along the river profile. We find that terrace preservation within the Gandaki catchment is largely focused within a catchment-wide tectonic window between the Main Boundary Thrust (MBT) and the Main Central Thrust (MCT), suggesting tectonics to be the primary control. Terrace long profiles are a commonly used method to distinguish between drivers of the terrace formation, deformation, and preservation in active mountain ranges and can provide insights into past events by comparing terrace elevation and slope with the modern channel. We further explore the differences in the deposition and preservation histories of terraces within the Gandaki catchment by automatically constructing terrace long profiles for each major river. Terrace profiles between the MBT and MCT are converted into normalised slope plots, comparing the downstream slopes of terraces to the slope of the modern channels. Terraces are then binned vertically, enabling the analysis of terrace profiles at varying heights above the channel. Through the observation of automatically generated terrace slopes, and supported by previous interpretations of terrace profiles, we find that terraces slope more steeply than the modern channel within tectonic accommodation which may reflect sediment oversupply into transport-limited systems, or steepened deposition from debris flows. Downstream towards the MBT and the Mahabharat range, we observe back-tilted terraces reflecting active tectonic deformation. Upstream and near the MCT, back-tilted terrace slopes may record tectonic deformation and past ponding events.
How to cite: Weir, E., Clubb, F., Densmore, A., Hurst, M., Sigdel, A., and Acharya, S.: Tectonic and climatic controls on fill terrace deposition and preservation in a large Himalayan river catchment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17853, https://doi.org/10.5194/egusphere-egu25-17853, 2025.
The Rio Santa Cruz in Southern Patagonia preserves a spectacular set of fluvial terraces along its approximately 200-km length across the Patagonian Steppe landscape, stretching from the proglacial Lago Argentino to the Atlantic Ocean. Exposure dating of the terrace levels using 10Be concentrations of surface cobbles has revealed ages ranging mostly from ca. 1 Ma to < 100 ka. Over this long spatial distance and wide temporal range, the terrace record provides a unique opportunity to explore how different mechanisms have affected landscape evolution in the Patagonian Steppe but also river long-profile evolution in a more general setting as they are often used to infer impacts of past environmental drivers. These drivers may include climate forcing in glaciated headwaters (including changes during the Mid-Pleistocene Transition), sea-level changes at the outlet, and geodynamic forcing above a slab window for the Patagonian context.
A first step in our analysis considers how climate forcing may affect aggradation and incision patterns along the river. We utilize GRLP (Wickert and Schildgen, 2019) to model the river long-profile response to (e.g. periodic and pulsed) changes in sediment and water input to specifically explore the magnitude and spatial extent of aggradation-incision cycles. We find that these scenarios, commonly explained as main driver of river terrace formation along whole fluvial systems, only generate aggradation-incision cycles for a limited upstream portion of the system. Further analysis steps include modelling river long-profile evolution due to lithosphere flexure by glacial loading and sea-level changes exposing different offshore slopes to the fluvial system. Results not only show main differences in the spatial and temporal process of terrace formation but overall highlight lag times between environmental forcing and channel evolution with terrace abandonment.
The transfer of these generic results back to the Río Santa Cruz points to different environmental forcings, upstream and downstream. In a last inverse modelling step, we highlight the potential of deriving and quantifying forcing parameters based on the observed terrace sequence along the river.
How to cite: Ruby, A., McNab, F., Schildgen, T., Wickert, A., and Fernandes, V. M.: Drivers of fluvial terrace formation and quantifying their impacts – Application to the Río Santa Cruz in Southern Patagonia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20063, https://doi.org/10.5194/egusphere-egu25-20063, 2025.
River valleys range from narrow and deeply incised canyons to broad and open valleys with valley floors that are many times wider than the river and accommodate large amounts of sediment. Floodplains in wide valley floors are areas of high biodiversity and have been important places in the development of human settlements. The intermediate storage of sediment along valley floors plays an important role in modifying chemical weathering fluxes and global element cycles, but also impacts the propagation of sedimentary signals. Despite the importance of valley floors as habitats and sediment traps, we still have a limited understanding on what controls the width, and hence the accommodation space, of valley floors. This knowledge gap currently prevents reliable predictions of how valley floors will evolve under changing environmental conditions.
Previous studies suggest that water discharge, lithology, uplift rate, and/or lateral sediment supply from hillslopes might exert some control on valley-floor width. But the results are ambiguous and the relative importance of each parameter remains unknown. Here, we quantify valley-floor width and each of the four potential control parameters at ~126,000 locations in 84 catchments along the Western Andes between 5° and 40°S. We rely on remote-sensing data and digitized maps. On the mountain belt scale, discharge exerts the strongest controls on valley-floor width, while lithology plays only a minor role. We investigated regional difference in the relative control on valley width by subdividing the data based on catchment boundaries and elevations. Correlation analyses suggest that discharge is a strong control especially at low elevation where discharge is highest, while uplift becomes a stronger control at higher altitudes. As such, our data are in line with observations from the Himalaya, where uplift has been shown as the strongest width control in higher elevations (Clubb et al., 2023). Our findings suggest that future changes in the discharge regime will preferentially impact valley-floor evolution at sites of low elevation and high discharge and help to interpret past tectonic and climatic boundary conditions from valley geometries.
Clubb, F. J., Mudd, S. M., Schildgen, T. F., van der Beek, P. A., Devrani, R., & Sinclair, H. D. (2023). Himalayan valley-floor widths controlled by tectonically driven exhumation. Nature Geoscience, 16(8), 739-746.
How to cite: Tofelde, S., Clubb, F. J., and Bookhagen, B.: Controls on valley-floor width in the western Andes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4010, https://doi.org/10.5194/egusphere-egu25-4010, 2025.
This study explores the formation, preservation, and uplift of relict low-relief surfaces in the Barkol Mountains, coupled with sedimentological and geochemical insights from the Hami Basin. By integrating digital geomorphic analysis, structural mapping, thermochronology, and sedimentary data, the research reconstructs the tectonic and geomorphic evolution of this region.
Using Shuttle Radar Topography Mission (SRTM) data (3-arc-second resolution), relict low-relief surfaces in the Barkol Mountains were identified based on slope thresholds (<14°) and hydrological analysis in ArcGIS. Cross-sectional profiles and slope-aspect analyses highlight tectonic influences, including fault-induced tilting and segmentation, with boundary faults playing a significant role in surface deformation.
Apatite fission track (AFT) analyses from granitic samples reveal prolonged slow cooling during the Late Cretaceous (124.6–63.5 Ma), indicating minimal exhumation and surface preservation. Younger AFT ages (50–55 Ma) near the southern boundary fault suggest Paleogene fault reactivation and accelerated cooling. Single-grain AFT ages from modern river sands on the southern slope are dispersed, with peaks at 135.7 ± 9 Ma, 86.4 ± 5.3 Ma, and 50.4 ± 4.7 Ma, corresponding to bedrock ages. Apatite (U-Th)/He (AHe) data corroborate these findings, with younger ages (~30 Ma) in faulted regions, reflecting enhanced exhumation due to tectonic activity. These results underscore the structural control of exhumation processes, contrasting slow hinterland cooling with rapid fault-zone cooling.
In the Hami Basin, sedimentological and geochemical analyses of Cretaceous and Cenozoic deposits link sediment provenance to tectonic uplift. Detrital AFT ages from basin sediments show peaks at ~170 Ma and ~100 Ma, aligning with erosion events in the Bogda and Harlik-Barkol Mountains. Geochemical analysis reveals that apatite ages from mafic rocks cluster in the Middle Jurassic, while those from granitic rocks concentrate in the Early Cretaceous, corresponding to sources in the Bogda and Harlik-Barkol Mountains, respectively. This pattern likely reflects the sequential uplift and exhumation of the Bogda and Harlik-Barkol Mountains.
In conclusion, the Barkol Mountains exhibit relict surfaces formed during slow Late Cretaceous cooling, disrupted by Paleogene fault reactivation and accelerated exhumation. Additionally, the Hami Basin archives sedimentary records of tectonic-driven erosion, offering insights into the interplay between tectonics, geomorphology, and basin evolution in the Eastern Tianshan.
How to cite: Zhao, Z., Wang, G., Shen, T., and Ma, C.: Meso-Cenozoic Tectonic and Geomorphic Evolution of the Eastern Tianshan: Insights from the Barkol Mountains and Hami Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2555, https://doi.org/10.5194/egusphere-egu25-2555, 2025.
The Himalayan mountains are dissected by some of the deepest and most impressive gorges on Earth. Constraining the interplay among river incision, glacial movement and rock uplift is important for understanding tectonic deformation in this region. We report here the discovery of a deeply incised canyon of the Yarlung Tsangpo River, at the eastern end of the Himalaya, which is now buried under more than 500 meters of sediments. By reconstructing the former valley bottom, analyzing sedimentary phase and dating sediments at the base of the valley fill, we show that fluvial sediment accumulation started at about 2 million 2.5 million of years ago, and extensive glacial advances occurred after ~0.75 million of years. Our findings reveal that rapid rock uplift is the direct cause of the high erosion rates within the gorge, which began to steepen about 2-2.5 million years ago. Notably, the earliest extensive glacial advance (~0.75 million of years) is considerably younger than the formation of the Tsangpo Gorge (>2.5 million of years). Following the initiation of this glacial advance, the Eastern Himalayan Syntaxis experienced rapid exhumation of approximately 1.3-1.6 kilometers. Such geomorphological processes and exhumation history suggest that rock uplift, rather than glacial damming, played a pivotal role in maintaining the stability of the knickpoints on the southeastern margins of the Tibetan Plateau.
How to cite: Wang, P., Hu, G., Wang, H., and Ge, Y.: Tectonic and climatic control of Yarlung Tsangpo Gorge revealed by a buried canyon in Southern Tibet, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3509, https://doi.org/10.5194/egusphere-egu25-3509, 2025.
A major challenge in magma-rich continental rifts, such as Afar, is to understand the evolution of fault networks in space and time. This is due to the lack of subsurface seismic reflection data and the presence of complex, variable-age lava flows at the surface. Most past studies have focussed on establishing tectonic history and fault evolution of onshore continental rift systems, with the help of geodynamic and analogue models. The dynamic response of fluvial landscapes to tectonic activity is an additional tool that can be used to better understand fault network evolution. However, little to no work has been done to date using quantitative geomorphology to understand the evolution of normal faults in magma-rich continental rift systems.
To deepen our understanding of fault evolution in these tectonic settings, this study focusses on the graben systems in the Central Afar region in Ethiopia, and small-scale streams that crosscut the graben fault systems. This study uses a combination of GIS DEM analysis, river long profiles, integrated with available ages of the lava deposits on the surface, to quantify landscape and geomorphic responses of river systems to extension in the Afar Region. The work done in this study provides new insights into the timing and magnitude of fault growth and interaction associated with normal faulting over timescales of 100,000 years.
How to cite: Chandresh, R., Keir, D., C. Whittaker, A., Corti, G., E. Bell, R., Sani, F., Pagli, C., La Rosa, A., and Tortelli, G.: Fault Evolution in Magma-Rich Rifts using Quantitative Geomorphology: Insights from Central Afar, Ethiopia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4765, https://doi.org/10.5194/egusphere-egu25-4765, 2025.
It is well understood that landscapes do not immediately adjust to changes in tectonic boundary conditions but instead undergo transient adjustments over time. Few studies have documented this transient adjustment by collectively examining fluvial, hillslope, erosional, and chemical weathering responses to tectonic perturbations. Here, we address this knowledge gap by investigating the Fiumara Allaro drainage basin, a ~98 km² catchment located in the Serre Massif of Calabria, Italy. The Fiumara Allaro is well-suited for such a study because it is predominantly underlain by granitic rock, has experienced a well-constrained order-of-magnitude increase in rock uplift rate at ~1.5 Ma, and benefits from high-resolution digital topographic data. Using a nested sampling approach, we collected data on channel width and grain size, and measured major element water chemistry as well as ¹⁰Be cosmogenic radionuclide concentrations along a transect from the steep lower reaches of the Fiumara Allaro to its high-elevation, low-relief upland. These data, combined with detailed topographic analysis, provide a holistic understanding of the landscape’s response to a step change in rock uplift rate. Geomorphic metric analysis reveals distinct contrasts between relict topography and actively incising regions, highlighting the transient nature of the landscape. Knickpoints are consistently observed at elevations between ~800 and ~1,000 m, separating the relict landscape from actively incising domains. Above the knickpoints, in the relict landscape, lower normalized steepness index (ksn) values (~10–30 m⁰.⁸) reflect slow fluvial incision and a limited response to tectonic forcing. In contrast, the actively incising landscape below the knickpoints shows elevated ksn values (~50–70 m⁰.⁸), indicating rapid incision and dynamic adjustment to increased uplift rates. Estimates of channel width, cast as the normalized wideness index, drop by more than a factor of 2 below the knickpoints, indicating channel narrowing after accounting for downstream increases in drainage area. Erosion rates in the relict landscape remain low, ~0.06–0.27 m/Myr, while rates downstream increase significantly to ~0.40–0.50 m/Myr, reflecting active incision driven by uplift. Grain size distributions further corroborate these trends: coarse material (D₈₄ ~731 mm) is concentrated in actively incising zones, while finer material (D₈₄ ~43–64 mm) dominates the relict landscape upstream. Preliminary water chemistry data indicate that cation concentrations generally increase below the knickpoints before declining further downstream, suggesting a potential coupling between physical and chemical weathering processes. Hillslope curvature analysis indicates that hilltops sharpen in response to active incision, reflecting ongoing transient adjustment to increased uplift rates. The Fiumara Allaro basin clearly exhibits geomorphic evidence of transient adjustment to uplift, with knickpoints and marked differences in erosion rates, ksn values, grain size distributions, and water chemistry trends between relict and incising domains, highlighting a delayed response to tectonic forcing. More detailed findings, along with an assessment of fluvial and hillslope response times and a discussion of the implications for physical and chemical weathering in transient landscapes, will be presented at the meeting.
How to cite: Ghamedi, O., Gallen, S., and Perez Hincapie, A.: Holistic quantification of transient landscape response to rock uplift changes in the Fiumara Allaro catchment, Calabria, Italy, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9329, https://doi.org/10.5194/egusphere-egu25-9329, 2025.
Neogene tectonics and geomorphic processes in response to Quaternary climate change drive landscape evolution in western Mongolia's Basin of Great Lakes (BGL). The endorheic Khyargas Nuur (Nuur=lake) in the BGL is the ultimate sink of a sequential water and sediment cascade from the adjacent Mongolian Altai and Khangai Mountains. Several intercalated lakes repeatedly joined as one major paleolake controlled by changes in atmospheric moisture supply and glacial meltwater influx throughout the Late Quaternary. Relict shoreline features up to +188 m above the modern lake (aml) provide direct geomorphic evidence of a mega (>13x modern area) paleolake Khyargas. Terrestrial cosmogenic nuclide (TCN) exposure dating of the highest observed shoreline of the Khyargas Nuur at +188 m aml, using a 10Be depth profile, provides a maximum temporal framework for the investigated paleoshoreline sequence. Notably, local offsets exist between expected and mapped/measured absolute beach ridge elevations. For example, absolute elevations for beach ridges associated with a +15 m aml lake level vary by up to 6.8 m with a standard deviation of 0.9 m (n=2760). Reconstructed beach ridge elevations vary by 10.9 ± 1.6 m for the prominent +118 m aml paleoshoreline (n = 2962). Luminescence dating of associated shoreline features yielded ages of ~2.1 ka and ~14 ka for the +15 and +118 m shorelines, respectively. Comparative statistical differences in the offset values of these two shorelines and concurrent spatial similarities of displacement hotspots suggest a time-dependent, cumulative paleoshoreline displacement mechanism. We hypothesize that observed shoreline offsets are induced by either (a) local tectonically active fault displacements, (b) hydro-isostatic adjustments similar to those observed around the margins of paleo-lake Bonneville in the U.S. Great Basin (1) and paleo Lake Chad (2) in north-central Africa, or (3) reactivation of zones of crustal weakness (old faults) caused by water loading and unloading. To evaluate the potential driving mechanisms on these displacements, we constructed a three-dimensional flexural isostatic model that utilizes paleoshoreline observations to determine rates and magnitudes of deflection and to test for robust constraints of the lithospheric effective elastic thickness (Te).
(1) Adams, K. D. & Bills, B. G. Isostatic Rebound and Palinspastic Restoration of the Bonneville and Provo Shorelines in the Bonneville Basin, UT, NV, and ID. in Developments in Earth Surface Processes vol. 20 145–164 (Elsevier, 2016).
(2) Mémin, A., Ghienne, J.-F., Hinderer, J., Roquin, C. & Schuster, M. The Hydro-Isostatic Rebound Related to Megalake Chad (Holocene, Africa): First Numerical Modelling and Significance for Paleo-Shorelines Elevation. Water 12, 3180 (2020).
How to cite: Wolf, D., Gelman, S., Wegmann, K., Ellis Curry, M., Marques Figueiredo, P., and Lehmkuhl, F.: Using paleolake shorelines to estimate lithospheric strength and response rates: Field observations and flexural isostatic modeling of Lake Khyargas, western Mongolia., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18945, https://doi.org/10.5194/egusphere-egu25-18945, 2025.
Extensive marine terraces preserved along the Cantabrian coast have been pointed out as good markers to understand the recent tectonic evolution of the Cantabrian margin in north Iberia. These landforms are interpreted as a single, kilometric-wide abrasion platform eroded during the Pliocene marine transgression (Mary 1983) which were later uplifted and faulted due to recent tectonic activity (Álvarez-Marrón et al., 2008). A recent study also points to continuous rising in response to lateral gradient in crustal thickness as a mechanism to explain the subtle variations in surface tilt observed only in the marine terraces of the western coastal areas (López-Fernández et al., 2020).
This contribution provides the first catchment-wide erosion rate estimates based on cosmogenic 10Be-26Al measured in two sediment samples retrieved from a 3.1 km2 extent fluvial basin incised in the marine terrace. The river basin is entirely composed by quartz-bearing rocks belonging to the Serie de los Cabos formation, which comprises alternating slate, sandstone and quartzite. Total incision since terrace formation reaches 80 m along the main river stream, while 21.2 m is the average incision achieved considering the total volume of material removed (ca. 60 Hm3) since the terrace uplift from an area of 283.3 Ha. Using the code Riversand v. 1.3.1 by Stübner et al. (2023), we computed catchment-wide erosion rates of 11.5 to 12.1 mm/ka based on 10Be and 17.3 to 18 mm/ka based on 26Al. These rates involved that at least 1.2 to 1.9 Ma are required to achieve ~21 m of averaged incision, which is in good agreement with previous minimum surface exposure ages of 1-2 Ma estimated combining 10Be-26Al-21Ne (Álvarez-Marrón et al., 2008). Similar analysis in other catchments might help to expand our current knowledge on the erosion patterns of these landforms, improving our understanding on competing mechanisms involved in the origin and dismantle of marine terraces.
Research funding: RETROCLIFF (PID2021-122472NB-100, MCIN/AEI/FEDER, UE) and GEOCANTABRICAE (SV-PA-21-AYUD/2021/51766, FICYT, Principality of Asturias, UE, ERDF).
References:
- Álvarez-Marrón, J., Hetzel, R., Niedermann, S., Menéndez-Duarte, R., Marquínez, J. (2008). Origin, structure and exposure history of a wave-cut platform more than 1 Ma in age at the coast of northern Spain: A multiple cosmogenic nuclide approach. Geomorphology 93, 316-334. https://doi.org/10.1016/j.geomorph.2007.03.005
- Mary, G. (1983). Evolución del margen costero de la Cordillera Cantábrica en Asturias desde el Mioceno. Trabajos de Geología 13, 3-35.
- López-Fernández, C., Llana-Fúnez, S., Fernández-Viejo, G., Domínguez-Cuesta, M.J., Díaz-Díaz, L.M. (2020). Comprehensive characterization of elevated coastal platforms in the north Iberian margin: A new template to quantify uplift rates and tectonic patterns. Geomorphology 364, 107242. https://doi.org/10.1016/j.geomorph.2020.107242
- Stübner, K., Balco, G., Schmeisser, N. (2023). Riversand: a new tool for efficient computation of catchmentwide erosion rates. Radiocarbon. https://doi.org/10.1017/RDC.2023.74
How to cite: Rodríguez-Rodríguez, L., Domínguez-Cuesta, M. J., Braucher, R., Cuervas-Mons, J., Aumaître, G., Keddadouche, K., Zaidi, F., and Jiménez-Sánchez, M.: Catchment-wide erosion rates relying on cosmogenic nuclides provide new clues on the evolution of marine terraces along the Cantabrian margin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6339, https://doi.org/10.5194/egusphere-egu25-6339, 2025.
The evolution of landscapes over time is governed by autogenic processes, such as sediment dynamics and landslides, and allogenic processes and factors, such as tectonics and lithology. The style of tectonic deformation governs the spatiotemporal distribution of rock types exposed at Earth’s surface, controlling how surface processes shape the landscape. The evolution of lithologically complex landscapes like fold-and-thrust belts remains incompletely understood because it is not clear how lithology affects the interactions between, and relative dominance of, different surface processes. The Appalachian Valley and Ridge physiographic province, an ancient fold-and-thrust belt, provides a unique natural laboratory for studying the interplay among tectonics, lithology, and surface processes. The region's diverse lithology is vividly displayed in exposed, breached anticlines, where resistant sandstones form ridges, and more erodible or weatherable carbonates and shales form valley bottoms in anticline cores. Breaching occurs when the crest is eroded, exposing deeper, often weaker layers. The mechanisms behind anticline breaching and breach expansion are not well understood and could be triggered by large episodic events, such as landslides, more gradual processes such as fluvial incision, or a combination of the two. In this study, we set up a landscape evolution model mimicking the evolution of Appalachian landscapes to investigate how autogenic interactions among fluvial incision, sediment dynamics, and landsliding respond to the lithological and structural variability found in ancient fold-and-thrust belts like the Appalachian Valley and Ridge province. We explore landscape evolution through a series of modeling experiments and develop new metrics to capture the dynamics of breached-anticline systems. By comparing metrics between modeled and real landscapes, we quantify the role of episodic landsliding in controlling anticline breaching and the dynamic evolution of tectonically inactive landscapes where the spatial distribution of different rock types governs landscape evolution.
How to cite: Campforts, B., Shobe, C., and Prince, P.: The influence of landslides on anticline breaching and landscape evolution in the Appalachian Valley and Ridge, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6992, https://doi.org/10.5194/egusphere-egu25-6992, 2025.
The central South Tian Shan, marked by high elevation, high relief, an uplifted relict landscape and interspersed intermontane basins, offers an ideal setting to study the far-field tectonic response to Indian-Asian convergence, and the interplay of topographic growth, erosion and climatic aridification since the late Cenozoic. Previous thermochronology studies from the highest massifs of the central South Tian Shan - the Khan Tengri and Pobedi massifs - reported accelerated exhumation since the Late Miocene (~ 10 Ma), linked to the reactivation of inherited structures propagating towards the Tarim Basin to the south. Little is known about the spatial distribution, timing and rates of erosion along the main fault structures in this region. To better address this question, we study exhumation associated with the Pobedi Thrust, a major Paleozoic fault with significant inferred Late Cenozoic reactivation. New apatite and zircon (U-Th-Sm)/He (AHe and ZHe) as well as apatite fission-track (AFT) data was collected along an elevation profile from both the hanging wall and footwall of the western branch of the Pobedi Thrust to quantify the low-temperature thermal history.
In contrast to enhanced Late-Miocene exhumation recorded in the Khan Tengri and Pobedi massifs, our samples from approximately 100 km to the west indicate dominant Mesozoic cooling and minimal Cenozoic exhumation, despite the region’s high (> 4 km) topography and significant (> 2 km) relief. Our southernmost sample provides a hint of exhumation associated with the South Tian Shan thrust (i.e., Maidan Fault), showing Late Paleogene AHe ages. 1D thermal history modeling suggests a phase of accelerated cooling of valley-bottom samples during the Late Miocene. Consistent with thermochronology data, mapping and interpolation of low-relief surfaces indicate Cenozoic tilting and deformation of the pre-Oligocene relict topography. These findings highlight spatially variable exhumation along the Pobedi Thrust and Maidan Fault and provide new insights into the complex Cenozoic tectonic activity of the central South Tian Shan and long-term landscape evolution processes.
How to cite: Gong, L., van der Beek, P., Sobel, E., Schildgen, T., Mariotti, A., Glodny, J., Kyiazbek, A., and Nurbek, S.: Cenozoic uplift and exhumation of the central South Tian Shan, Kyrgyzstan , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11719, https://doi.org/10.5194/egusphere-egu25-11719, 2025.
On January 1st, 2024, the Mw 7.5 Noto Peninsula earthquake ruptured on a series of coastal offshore reverse faults in the back arc of central Japan. Closest to the rupture, in the northwest, the coastal rocks uplifted as much as 4.4 m (Fukushima Yo et al., 2024). The coastline accordingly moved seaward by up to 200 m creating new wide bedrock platforms. Recent Holocene terraces mapped along the northern coast (Shishikura et al., 2020), where coseismic uplift was greatest on January 1st 2024, suggest similar past ruptures. Many of the ruptured faults follow the coast at a depth of ca. 60 m below modern sea level. This is the average elevation of sea level over the last 500 kyr, and strongly suggests that these faults define the extent of the continental domain.
The Peninsula itself hosts 4767 unique mapped terraces ranging in age from Holocene to 1.02 Ma (Ota and Hirakawa, 1979, Koike and Machida, 2001). The terraces associated with the last two interglacial high stands (ca. 120 and 234 ka) record a tectonic SE-tilting similar to that of the Mw 7.5 earthquake. Older terraces all record a spatially uniform rate of uplift across the Peninsula. The landscape itself does not appear to be equilibrated to this gradient in uplift, with a seemingly disconnected fluvial geometry. We conclude that the faults that caused the most recent earthquake became the dominant structures on the Peninsula around 250 ka and that the Peninsula is in a state of transient equilibration.
80 km northeast of the Noto Peninsula lies the Island of Sado. The Island is made of two mountain ranges oriented SW-NE along the main tectonic lineation of the back arc, roughly parallel to the northern coast of Noto Peninsula. The marine terraces of the northern range, Oosado, record a strong southeast tilting synchronous and similar to that observed on the Noto Peninsula. The landscape morphology is not equilibrated to this pattern of deformation either. Earlier work by Ota et al., (1992) suggested that the tilt is driven by a fault lying just offshore of the Oosado coast. Closer inspection of the bathymetry reveals a ramp at around -60 m reflecting a geometry similar to the Noto Peninsula. The lessons from the Noto Peninsula earthquake can be applied to Sado Island where information about the seismic cycle is lacking. It confirms the hypothesis of Ota et al. (1992) and highlights a potential seismogenic source close to the shore.
Koike, K., & Machida, H. (2001). Atlas of Quaternary… Tokyo: University of Tokyo Press.
Ota, Y., & Hirakawa, K. (1979). Marine terraces and… Geographical Review of Japan, 52(4), 169–189.
Ota, Y., Miyawaki, A., & Shiomi, M. (1992). Active Faults on Sado Island… Journal of Geography (Chigaku Zasshi), 101(3), 205–224.
Shishikura, M., Echigo, T., & Namegaya, Y. (2020). Activity of the off-shore… Active Fault Research, 53, 33–49.
How to cite: Malatesta, L. C., Sueoka, S., Weiss, N.-M., Gailleton, B., Tsukamoto, S., Ishimura, D., Nishimura, T., Takahashi, N., Kataoka, K., Komatsu, T., and Iwasa, Y.: Active faults and coastal landscapes in the back arc of Central Japan, lessons from the Mw 7.5 Noto Peninsula earthquake, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11196, https://doi.org/10.5194/egusphere-egu25-11196, 2025.
The combined record of past sea levels and crustal deformation can be found in the landscapes of tectonically active coastlines. Marine terraces, sea cliffs, or intertidal platforms all reflect the work of multiple geomorphic processes sculpting the coast. Researchers have investigated the key erosional mechanisms responsible for shaping the coasts. Field observations suggest that platform formation is driven by three primary processes: (1) mechanical erosion from the kinetic energy of marine waves, (2) physical or chemical weathering driven by wetting-drying cycles, and (3) biochemical weathering, which may amplify or even sometimes dominate the other two processes. However, determining the dominant process remains challenging, as each mechanism is interacting with other processes, making it is hard to disentangle their relative contribution. Numerical models for coastal evolution exist but we are not able to properly evaluate their accuracy, or to convincingly simulate the respective roles of different processes over 100s of kyr.
In this study, we compare and assess the outputs of models that emphasize different processes by simulating the shoreline evolution trajectories under identical (or varying) wave conditions and sea level scenarios. The results reveal that the shape of coastal topography, including intertidal platform, varies significantly depending on the dominant process or assumptions, such as the rate of debris removal from failed cliffs. Notably, these differences become more pronounced when considering the direction of sea level change. Additionally, we build a framework that enables the simulation of process combinations by selectively activating or deactivating specific modules within the system. By systematically comparing models and their combinations, we aim to develop a comprehensive framework for coastal erosion that can be adapted to specific sites and conditions.
Looking ahead, we seek to link these distinct platform development trends to long-term coastal morphological features, such as marine terraces. Over geological timescales characterized by glacial sea level fluctuations, prolonged platform formation may produce distinct marine terraces. Understanding these trends in coastal erosion can provide valuable insights into the generation and preservation of coastal geomorphology.
How to cite: Keum, D., Malatesta, L., Tsukamoto, S., Huppert, K., Bovy, B., and Braun, J.: From Short-Term Erosion to Long-Term Landforms: Linking Different Coastal Erosion Models to Marine Terrace Formation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12302, https://doi.org/10.5194/egusphere-egu25-12302, 2025.
Over recent decades, innovative quantitative methods have been developed to study the internal dynamics of river basins. Most of these approaches assume stable or minimally drainage divide mobility (DDM), based on the premise that the rate of river network evolution is significantly faster—by several orders of magnitude—than the mobility of drainage divides. However, recent studies challenge this assumption, showing that the Gilbert metrics can effectively measure DDM and reveal scenarios where drainage divides shift more rapidly than river network adjustments. This dynamic complicates the interpretation of river profiles. In particular, χ-values near headwaters have been identified as indicators of DDM, with low χ-value catchments tending to migrate towards those with higher χ-values. Yet, this interpretation hinges on the premise that mean rock uplift rates, erodibility, and base level heights are consistent across the system. Over geologic timescales, such uniformity is improbable across entire mountain ranges, thereby limiting the universal applicability of this tool. Therefore, thoughtful evaluation of potential DDM is crucial for understanding landscape evolution and also how drainage divide contains information on past climatic and tectonic forcings itself. In this study, we focus on an endorheic watershed in the hyperarid core of the Atacama Desert, northern Chile. The hyperarid conditions present in the Atacama Desert provides a unique opportunity to capture geomorphic signatures as far back as the Paleogene evolutionary stages. We propose a downscaling analysis of DDM applied to three local-scale watershed divides. By integrating geomorphological mapping, morphometric indices, and existing geochronological data, we aim to evaluate DDM across representative sections at a local scale. Furthermore, these results will be validated using forward landscape evolution modeling in Landlab 2.0. Our findings are expected to provide quantitative estimates by comparing widely recognized metrics. We also emphasize the utility of χ-values and Gilbert metrics in sub-catchments to decipher local-scale landscape changes within a basin characterized by multiple evolutionary stages. This downscaling approach refines our capacity to interpret and forecast landscape evolution with exceptional spatial precision, even within the context of an extreme climatic environment, offering profound insights into the complex interactions among tectonic, climatic, and geomorphic processes.
How to cite: Cisternas, R., Olivares, L., López, C., Riquelme, R., Baltazar, I., Espinoza, S., Rebolledo, M. C., Herrera, B., and Ríos-Contesse, J.: Extending the limits of divide migration criteria: A downscale approximation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14831, https://doi.org/10.5194/egusphere-egu25-14831, 2025.
In the northern Andes of Colombia, seismic and tomographic studies evidence a slab relay between the gently dipping northern Bucaramanga segment and the southern steeply inclined Cauca segment. These studies indicate a clear-cut change in the sub-continental slab constellation and evidence of a lithospheric tear. Superficial structural and geomorphic changes above this relay zone depend on the observation scale and are best developed in the Eastern Cordillera of Colombia, a bi-vergent mountain belt decoupled from the Andean main trunk, which evolved by the inversion of an Early Cretaceous foreland basin. At the transition from steep to flat slab segments, this mountain belt doubles its width and attains considerable heights by a combination of exhumation and surface uplift. The external part of the tear coincides with the cratonward-oriented deformation front of the Eastern Cordillera. Here, faults are related to tight, basement-involved folding, suggesting a high geothermal gradient for this ductile deformation style. The youngest structures are represented by domes aligned parallel to the structural trend. These domes overprint existing folds and suggest by their size and association to circular normal faults growing and decaying evolutionary stages, demonstrating a southward propagation of a thermal mantle anomaly. In the western Central Cordillera, transversely oriented monogenetic volcanic fields similarly show a recent southward propagation of volcanic activity. A southward shift of the slab tear is further evidenced by transversely oriented fold trains. This scenario of a southward migrating slab tear encourages us to undertake a morphological study to evaluate the maturity of drainage and landscape evolution and to corroborate an N-S younging of recent tectonic activity. A reference for recent tectonic activity is the volcanic center of Paipa, centered along a fissure-like caldera and aligned transversely to the regional fold trend, indicating axial extension. Additionally, a subvolcanic rhyolitic stock has refolded a flank of an existing fold diapirically. These crustal mobilizations occurred during and after the late Miocene folding (implying NW-SE shortening) and before a second fold phase related to E-W shortening during the Cordillera’s final uplift stage. We use a novel analysis to identify the degree of directional organization of small river segments compared to the local structural trend. The reorganization of drainage indicates ongoing folding and tilting of hanging wall blocks related to major reverse faults and regional tilting of the cordillera’s axial depression. The capture of previously established longitudinal river valleys of the high plains documents the dynamics of transverse drainage during the final uplift and exhumation of the Cordillera’s eastern flank. The deviation of transverse rivers along frontal folds helps identify actively forming structures. Conversely, the weakly preferred drainage orientation in the axial depression north of the tear suggests a more mature landscape. With these geomorphological criteria, we aim to discuss the dynamics of the Caldas Tear and its southward propagation. Did the shallowing of the subducting plate occur gradually, involving lithospheric bending, or was it caused by the migration of a tear that swept through the Cordilleran realm until reaching its present southern position?
How to cite: Kammer, A., Zeilinger, G., and Saavedra Serrano, J. S.: New structural and geomorphological observations at the transition from shallow to steep subducting plate along the Caldas Tear in the Colombian Cordilleras, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16921, https://doi.org/10.5194/egusphere-egu25-16921, 2025.
The impact of Quaternary glaciations on denudation rates has long been debated and the proposition of the instability of climate as a driver of higher denudation rates since the Pliocene has yet to be proven. Most denudation rate reconstructions have focused on areas either tectonically active or glaciated, or both during that period, leading to difficulty in quantifying the impact of climate cyclicity on denudation, as the deciphering of climatic over tectonic control on denudation can be challenging, and glacial erosion appears to be non-linear, and overprints any other forcing. Furthermore, these studies have mainly concentrated on northern hemisphere or high latitude regions. A global increase of denudation implies other regions should be equally impacted but a large gap in data and knowledge exists in low latitude Tropical regions. Therefore, key regions to better understand the impact of climate on denudation should be free of tectonic activity or glacial processes and located under the Tropics.
In this work, we propose to quantify paleo-denudation rates of the Ogowé catchment (Gabon) over Plio-Pleistocene times by measuring 10Be in quartz grains collected from turbidite samples of three cores and one probe collected 30 km to 200 km offshore the mouth of the Ogowé river. To better constrain transport times of these sediments and quantify their ages of burial, we also measure both radiocarbon ages of vegetal debris contained in the turbidites and 26Al/10Be ratios.
Our results show near constant denudation rates over the Pliocene, leading to two possible conclusions. Either the Quaternary climatic cycles did not affect local tropical climate of the Ogowé region, or denudation rates remain unaffected by climatic variability, at the scale of 10 ka to 100 ka.
How to cite: Large, E., Charreau, J., and Blard, P.-H.: Limited effect of Quaternary climatic cycles on tropical denudation from10Be paleo-denudation rates of the Ogowé catchment (Gabon), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17366, https://doi.org/10.5194/egusphere-egu25-17366, 2025.
The Mid-Pleistocene Transition (MPT; ~1.2–0.9 Ma) marked a shift in global climate cycles, amplifying glacial-interglacial oscillations and lengthening their periodicity. In the Patagonian Andes, intensified erosion due to late-Miocene glaciation is well documented, but geomorphic evidence also suggests accelerated exhumation after the MPT. The Southern Patagonian Icefield, draining into Argentino Lake and the Santa Cruz River, provides a direct link between glacial erosion and downstream fluvial systems. To quantify these impacts, we combine Apatite (U-Th)/He thermochronology and cosmogenic 10Be dating. Single-grain apatite (U-Th)/He ages from bedrock bordering Argentino Lake, and an 1175 m elevation profile, range from ~4–8 Ma, with apparent exhumation rates of ~0.28 km Ma⁻¹. Coupled thermal and landscape modeling suggests an acceleration of erosion post-4 Ma. Downstream, 10Be-dated fluvial terraces of the Santa Cruz River reveal incision rates of ~0.13–0.18 km Ma⁻¹ over the last 1 Ma, with transient acceleration (~0.66 km Ma⁻¹) between 1.03–0.93 Ma, coinciding with intensified glaciation after the MPT. Terrace ages also show a shift from shorter periodicities to 100-kyr cycles. Our results suggest the MPT triggered enhanced glacial erosion in the Andes, influencing sediment discharge and downstream channel-bed elevation. This study highlights the MPT’s measurable impact on both glacial source areas and downstream depositional systems.
How to cite: Milanez Fernandes, V., Schildgen, T., van der Beek, P., Wittmann, H., Sobel, E., Friedrichs, B., Ruby, A., McNab, F., and Georgieva, V.: Linking Glacial Exhumation and Fluvial Incision During the Mid-Pleistocene Transition, Southern Patagonia, Argentina, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19506, https://doi.org/10.5194/egusphere-egu25-19506, 2025.
Understanding the provenance and transport pathways of sediments is crucial for reconstructing the geological history of source-to-sink systems. Northern Colombia, with its complex tectonic and geomorphological settings, provides an ideal framework to study the connectivity between coastal and offshore sedimentary systems. The Magdalena River Delta (MRD) and La Aguja Canyon (LAC), two prominent features in the Caribbean Sea, serve as major conduits for sediment transport from continental to deep marine environments. This study analyzes detrital zircon U-Pb geochronology data from four coastal sediment samples collected near the MRD and LAC, along with ten offshore samples retrieved during a research expedition aboard RV Maria S. Merian, using a Giant Box Corer at ~50–4000 m depths. A total of 1550 extracted zircon grains were analyzed by LA-ICP-MS to determine U-Pb ages and trace element compositions, enabling sediment provenance identification.
Zircon U-Pb ages range from <1 to 2620 Ma in the MRD and 50 to 1798 Ma in the inner LAC, with younger ages down to 2.7 Ma in the outer offshore regions. Coastal zircons from LAC are generally larger (>200 µm) than those from the MRD (~50–150 µm), reflecting differences in sediment transport and source rock characteristics. Offshore zircons show more consistent sizes (~50–200 µm) across both regions. The morphology of the grains varied from equant and elongated grains to broken grains with rounded terminations. Cathodoluminescence (CL) imaging reveals oscillatory zoning typical of magmatic zircons, homogeneous or rim-core zoning indicative of metamorphic origins, and grains with no CL response, suggesting prolonged surface exposure.
The youngest age clusters in the MRD, spanning 0.1 to 8 Ma, 75 Ma, 155 Ma, and 275 Ma, indicate contributions from the Central Cordillera of Colombia, highlighting recent contributions from this tectonic unit. Ages from 459–682 Ma suggest additional input from the Santander Massif and San Lucas Range, while older clusters (916–2232 Ma, largest peak at 991 Ma) reflect influences from the Eastern Cordillera. These age distributions underscore the interplay of tectonic uplift and fluvial transport in shaping sediment deposition in the MRD. Coastal samples near the MRD show age distributions that correlate well with offshore samples, particularly for peaks below 300 Ma and above 860 Ma. However, coastal samples lack significant ages in the intermediate range (~300–860 Ma), contrasting with the offshore spectrum, which exhibits a more continuous distribution with only a minor gap between 700 and 800 Ma. In LAC, prominent U-Pb age peaks at ~50 Ma, ~180–265 Ma, and ~1000 Ma denote provenance from the Santa Marta Batholith and its adjacent units, including gneisses, metasediments, and the Santa Marta and San Lorenzo Schist. Coastal samples near LAC display comparable provenance signals, with dominant contributions from the Santa Marta Massif. These findings highlight the influence of tectonic activity in the Santa Marta region on sediment delivery to both coastal and deep marine environments.
Keywords: detrital zircon U-Pb geochronology, source-to-sink, Magdalena River Delta, La Aguja Canyon, marine sediment provenance
How to cite: Villanueva-Garcia, E., Rojas-Agramonte, Y., Rincón-Martínez, D., Winter, C., and Rösel, D.: Sediment provenance from coastal and offshore northern Colombia: Detrital zircon U-Pb geochronology of the Magdalena River Delta and La Aguja Canyon, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17109, https://doi.org/10.5194/egusphere-egu25-17109, 2025.
A significant portion of Zrinska Gora mountain in Croatia is covered by Paleogene siliciclastic deposits. These deposits are thought to have formed in a flexural foreland basin that developed during the Late Cretaceous and Paleogene along the northwestern segment of the Sava Zone, a tectonic unit formed by the continental collision of the Adria plate and the Tisza Mega-Unit (Ustaszewski et al., 2010).
This study investigates the sedimentological and petrological characteristics of Paleogene sedimentary deposits, focusing on conglomerates, to reconstruct their provenance and depositional history. Our methodology included sedimentological logging and sampling, optical microscopy and heavy mineral analysis. Detailed petrographic investigation of conglomerate pebbles resulted in the determination of 12 lithotypes, comprising various magmatic, volcaniclastic, cataclastic, and metamorphic rock types, based on their mineralogical and structural-textural characteristics. Associated sandstones classify as litharenites with phyllosilicate and hematite cement, containing rock fragments similar to the lithologies observed in the conglomerate pebbles.
Provenance analysis suggests that the clastic material primarily originated from units of the Sava Zone, as indicated by granophyre, syenite, and monzonite clasts. Volcanic pebbles point to mixed sources from various Mesozoic complexes, while metamorphic clasts reflect contributions from pre-Eocene formations across the broader area, exhibiting medium- to high-grade regional metamorphism. Notably, a slight shift in heavy mineral composition across the studied localities suggests a relocation of the primary sediment source, possibly from the Western Vardar Ophiolitic Unit to the Sava Zone and Tisza Mega-Unit, reflecting tectonically driven sedimentary reorganization in the foreland basin. These findings provide new and preliminary insights into the development of clastic sediments in syncollisional basins along the northwestern part of the Sava Zone during the Paleogene. The presented work is supported by the Croatian Science Foundation project SECret (HRZZ IPS-2023-02-2683).
References:
Ustaszewski, K., Kounov, A., Schmid, S.M., Schaltegger, Fügenschuh, B. et al. (2010): Evolution of the Adria‐Europe plate boundary in the northern Dinarides: From continent‐continent collision to back‐arc extension. Tectonics, 29(6), 34.
How to cite: Plavac, M., Lužar-Oberiter, B., and Petrinec, Z.: Indications of Provenance and Source Rock Contributions in Paleogene Deposits from Zrinska Gora, Croatia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18576, https://doi.org/10.5194/egusphere-egu25-18576, 2025.
The extent that climate impacts erosion has long been debated and is difficult to decipher, as climate signals are often obscured by tectonic signals. The Hawaiian Islands are excellent settings to test these relationships, as they have no tectonic uplift, well-known base level histories, uniform lithology, and dramatic climate gradients. On Kauai, previous work shows a correlation between rainfall and total canyon incision; however, geologic evidence shows that river incision could not have been constant throughout time: ~2 Ma inset lava flows sit at river level in several canyons on the ~4.5-million-year-old island, indicating that canyon incision has been negligible over the last 2 Myr. One explanation is that boulders and/or sediment flux in streambeds block further incision, acting as thresholds. Channel gradients on the Hawaiian Islands decrease with increasing precipitation and appear to be in equilibrium (uniform ksn below knickpoints), indicating that channel gradient is set by the threshold of boulder or sediment mobility. Therefore, climate appears to be recorded in threshold channel slope and total incision depth instead of time averaged incision rate as previously assumed (Ferrier et al., 2013). We traveled to Kaui and West Maui to test the hypotheses that (a) boulders and/or (b) sediment act as thresholds for fluvial incision, by (a) quantifying channel morphology and boulder size using structure from motion photogrammetry, drone photography and pebble counts, and (b) collecting catchment-average samples for cosmogenic radionuclide analysis (36Cl in magnetite), in catchments across gradients of precipitation rate and channel slope. Preliminary data suggests that boulder size scales with channel gradient within climate zones, indicating that boulders are an important threshold for channel incision. However, if channel gradient is correlated with upcoming denudation rates, sediment flux may be an additional important threshold. Next steps include quantifying basal and critical shear stress for boulder transport and combining data into a landscape evolution model. Ultimately, we aim to answer long-standing questions regarding the roles of climate and fluvial thresholds in landscape evolution, applicable in both tectonically inactive and active landscapes.
How to cite: Lodes, E., Colaianne, N., Raming, L. W., Whipple, K. X., Yager, E., Granger, D. E., and Strauch, A. M.: Controls of climate and fluvial thresholds on stream incision on the Hawaiian Islands , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20636, https://doi.org/10.5194/egusphere-egu25-20636, 2025.
The Tripura fold-thrust belt is located at the eastern fringes of the Bengal basin, which is also part of the Himalayan foreland basin. It is also considered situated at the outer wedges of deformation front of the Indo-Burmese ranges, eastern Himalayas. It has been developed due to the oblique collision of the Indian, Eurasian, and Burmese micro-plates over the past 2 million years, leading to new antifomal ridges in the western region. It comprises a series of N-S trending narrow antiformal ridges separated by wide synformal valleys. In North and East Tripura, the major rivers such as Khowai and Dhalai flow through the intermontane valley to the north, eventually merging with rivers in Bangladesh. Meanwhile, in West Tripura, rivers like Haora and Gomti flow westward, joining with rivers in Bangladesh. The shifting of major rivers like Khowai and Haora northwards within the antiformal ridges indicates neo-tectonic activities along the transverse fault. Recent Earthquake activities in the area also emphasize that the area is tectonically active. However, due to its inaccessible location, dense vegetation, and ongoing border disputes have resulted in limited research attention. Based on previous structural studies, a series of N-S trending parallel antiformal ridges show a progressive decreasing structural complexity from East to West; however, limited or no systematic studies are available to understand the sequential development of these ridges and valleys concerning tectonic and chronological framework.
Our research aims to establish a geochronological framework in the late-quaternary geomorphic evolution of the Tripura fold-thrust belt which has been lacking. Using geomorphic studies and optically luminescence dating techniques, we provide a timeline of sediment deposition and new antiformal ridge formation in the westernmost part of the area during the Late Quaternary period, leading to a better understanding of the sequence of events operating in the landscape evolution. Primary field observation suggests a thick deposition of unconsolidated sand and silt layers showing a fining upward sequence preserved at the flank of ridges. In the westernmost part of Tripura, based on 22 luminescence ages dated from unconsolidated sand samples suggested that it was a plain depositional fluvial system during 87, 84, 79,76,74 ka or even older than that and continued to deposit around 68, 65,63 till 55 ka. During that time, there was a high sediment supply in the area. Due to tectonic activities, the Baramura and Atharamura ridges started to develop after 50 ka, evident from the luminescence dates from the top layer of sand deposits preserved in the crest of the ridges. Climate fluctuations significantly influenced sediment supply for fluvial deposition, which was subsequently affected by ongoing neo-tectonism in the Indo-Burmese ranges. Additionally, it also corresponds with the transition during arid-humid phases that prevailed over the Northern Hemisphere in the global scenario.
How to cite: Kar, R. and Jaiswal, M. K.: Late Quaternary landscape evolution of the frontal part of Tripura Fold Thrust Belt, India: Connecting climate and tectonics, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-884, https://doi.org/10.5194/egusphere-egu25-884, 2025.
For tens of millions of years, up until the late Eocene, Afro-Arabia was subjected to intense chemical weathering under warm and wet climatic conditions. Geodynamic quiescence promoted the development of a widespread carapace of etchplains that capped the stable continent. Starting in the late Eocene, the impingement of the Afar mantle plume on the base of the Afro-Arabian lithosphere resulted in domal uplift across large areas surrounding the Red Sea. The carapace of deeply weathered rocks flexed, eroded, and eventually became incised, facilitating the erosion of underlying pristine rocks. Since at least the early Oligocene, the Afro-Arabian dome has been draining into the Levant Basin of the Eastern Mediterranean, providing the basin with an outstanding sedimentary record of the large-scale uplift. In this study, we evaluate stages in the rise of Afro-Arabia by probing the mineralogical and geochemical properties of Oligocene-Miocene clay recovered from the Levant Basin boreholes. The lower part of the siliciclastic section in the Levant Basin, dating back to 33 Ma, is composed of kaolinite-rich sediments sourced from the weathering and erosion of Neoproterozoic crystalline rocks of the Arabian-Nubian Shield. We interpret them as erosion products of the etchplains that once capped Afro-Arabia and were dismantled during the early stages of mantle-induced domal uplift. Higher up in the siliciclastic section, illite-smectite gradually becomes more prominent at the expense of kaolinite, reflecting further uplift and downcutting into the pristine bedrock. Since the early Miocene, fluvial incision was enhanced by the superimposed effects of regional doming and flexural uplift along the Red Sea Rift margins. By 20-15 Ma, the proportion of illite-smectite surpassed that of kaolinite in the Levant Basin sediments, signifying the substantial elevation of Afro-Arabia and the establishment of high topography. The sedimentary fill of the Levant Basin allows tracking the peeling of the rising continent and offers unique, independent constraints on the uplift process.
How to cite: Glazer, A., Avigad, D., and Morag, N.: Timing the Oligocene-Miocene uplift of Afro-Arabia: Insights from clay mineralogy and geochemistry, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9832, https://doi.org/10.5194/egusphere-egu25-9832, 2025.
Species range limits are typically constrained by their tolerance to abiotic factors such as climate, as well as by dispersal limitations due to geographic barriers like mountain ridges and river valleys. Montane regions, which are hyperdiverse in many different clades, and characterised by high turnover, and complex topography, provide ideal systems for investigating the drivers of range limits. In this study, we collected 30 environmental DNA (eDNA) samples from the tributaries of the Salween, Mekong, and Yangtze rivers and employed ITS2 primers to analyse the species composition of plant and fungal communities. We then quantified and partitioned the relative contributions of geographic and climatic isolation to the assembly of these communities. Our analyses revealed a congruent distribution pattern between plant and fungal groups, with distinct segregation across different river valleys and along latitudes. Habitat preference analyses indicated that our eDNA samples predominantly captured mid-to-low elevation species. The taxonomic composition of plant and fungal communities was jointly influenced by geographic and climatic isolation, although the strength of these influences varied across different groups. Fungal communities were more strongly affected by geographic isolation, while plant communities were more influenced by the combined constraints of geography and climate. These findings underscore the joint influence of topographic and climatic isolation in shaping community composition, highlighting the importance of environmental filtering and dispersal limitation processes. We conclude that the high biodiversity in montane regions depends on both complex climate and topography and, secondarily, note that riverine environmental DNA provides an efficient approach to understand geological and climatic mechanisms in driving biodiversity patterns in terrestrial clades.
How to cite: Chang, Y., Wang, Y., Zhong, W., Zhang, X., Albouy, C., Zimmermann, N., Willett, S., and Pellissier, L.: Environmental DNA reveals geologic and climatic isolation effects on plant and fungal Communities in the Hengduan Mountains, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16343, https://doi.org/10.5194/egusphere-egu25-16343, 2025.
River terraces are common features in landscapes around the world, created through the interaction of erosion and sedimentation processes. Although these terraces are widespread, many aspects of their formation and development remain unclear, especially regarding the mechanisms and conditions that control their evolution. The Guadix/Baza Basin in Andalusia, situated within the Granada UNESCO Geopark, offers a unique natural laboratory for studying these questions. Over time, this basin has undergone substantial geological transformations. Initially, it was a closed depression where sediments from the surrounding mountains accumulated. During the Middle to Late Pleistocene, a river capture event caused the basin to transform into an open river system, leading to the development of several generations of river terraces. These terraces are often associated with calcareous sinter formations found in deeply incised valleys. A key factor in the basin's evolution is its dynamic neotectonic activity. The area is characterized by a complex system of faults, with the Baza Fault acting as a major fault system dividing the research area into two distinct sub-basins.
The aim of our DFG-funded research project is to study the processes that influenced the evolution of the fluvial system after the river capture, with a particular focus on fluvial erosion dynamics. To reconstruct the development of terrace formation, luminescence dating is applied to terrace sediments, while U/Th dating is used for associated calcareous sinter formations. This combination allows the establishment of a chronostratigraphy, providing insights into the rates of erosion and the incision patterns of local rivers.
Our contribution will present an overview of the project’s objectives, outline the applied methods, and discuss initial results, including the first chronostratigraphy of the eastern Baza sub-basin. A key focus will be placed on the influence of tectonic activity on terrace formation and how these forces shaped the development of the regional river network. Preliminary findings suggest that tectonics played a significant role in terrace formation, influencing both the thickness and depositional patterns of sedimentary layers. This, in turn, has implications for the interpretation of dating results, as the tectonic setting directly affects the stratigraphic context and preservation of terrace sequences.
The study highlights the importance of integrating numerical laboratory results with empirical fieldwork. A comprehensive understanding of terrace evolution and sedimentary processes is only achievable when the specific tectonic framework of the study area is carefully considered.
How to cite: Kögler, L., Wolf, D., García Tortosa, F. J., Faust, D., Fuchs, M., and Kolb, T.: The influence of tectonics on river terrace evolution in the Guadix/Baza Basin, Spain, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4398, https://doi.org/10.5194/egusphere-egu25-4398, 2025.
Regions dominated by active fold and thrust belts are prone to the development of new, unstable slopes as deformation progresses. However, studies examining the spatial distribution and behavior of landslides within the Himalayas—one of the world’s most dynamic mountain systems—remain limited. This study presents a detailed landslide inventory for the Sikkim Himalayas, an area marked by vigorous tectonic activity and steep, rugged landscapes. By analyzing satellite imagery, we compiled over 100 large-scale landslides (each exceeding an area of 106 m²), with many of these still exhibiting active movement. We utilized tools such as TopoToolbox to analyze topographic steepness and concavity indices, as well as factors like proximity to rivers and active faults. Additionally, geomorphic indices of active tectonics, lithological variations, and rainfall patterns were integrated to investigate the relationship between landslide distribution and these variables within sub-basins as well as across major thrust zones. In Sikkim, landslides show a pronounced tendency to cluster at higher elevations, specifically in the zone between the Main Central Thrust (MCT) and the South Tibetan Detachment (STD). These events are predominantly concentrated in areas with significant local relief and are closely linked to regions experiencing higher rates of relative tectonic uplift. Moreover, extreme rainfall driven by orographic effects amplifies landslide activity, particularly in regions with steep terrain. The most affected areas include the uppermost, steepest areas of active thrusts (MCT and Main Boundary Thrust) and inclined escarps of deeply incised valleys.
How to cite: Das, S. and Scaringi, G.: Tectonic, lithologic and climate controls on landslide distribution in the Eastern Himalayas, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5241, https://doi.org/10.5194/egusphere-egu25-5241, 2025.
