The sediment dispersal patterns at active orogens are highly sensitive to changes in the landscape configuration triggered by the combined effects of deformation, volcanism, and geomorphological processes. Hence, reconstructing source-to-sink systems provides valuable insights into the interplay between deep-seated and surface processes as controls of the coupled development of mountain ranges and intermontane sedimentary basins.

The Oligocene-Miocene evolution of the Colombian Andes has been shaped by subduction tectonics and the collision of an oceanic terrane, which are linked to changes in the kinematics of crustal deformation and the tectono-magmatic history of continental arcs. Nevertheless, the combined effect of such processes on the growth of the Western and Central Cordilleras and the associated intermontane basins remains elusive.

Here, we use a large dataset of detrital zircon U-Pb ages from Oligocene-Pliocene strata of intermontane basins of western Colombia, and available (bio)stratigraphic and structural constraints to reconstruct: i) the regional-scale configuration of source areas and accumulation settings, ii) the sediment routing systems, and iii) the history of basin connectivity. We interpret the sediment dispersal patterns as controlled by the pulsed uplift of the Central and Western Cordilleras linked to a syn- to post-collisional transpressional tectonic regime, and to changes in the drainage network driven by intra-basinal arc-related magmatic activity

How to cite: León, S., Faccenna, C., Conrad, E., and Valencia, V. A.: The role of tectonic, volcanic, and fluvial processes as controls of Neogene intermontane basin evolution in the western Colombian Andes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18362, https://doi.org/10.5194/egusphere-egu24-18362, 2024.

Releasing and restraining bends are complementary features of continental strike-slip faults. The Dead Sea Basin of the strike-slip Dead Sea Fault is a classical example of a releasing bend with an asymmetric, deep basin structure. However, the intrinsic relationship to its northern counterpart, the restraining bend that created the Lebanese mountains, remains unclear.

Here, we present 3D coupled geodynamic and landscape evolution models that include both the releasing and the restraining bend in a single framework. These simulations demonstrate that the structural basin asymmetry is a consequence of strain localization processes, while sediments control the basin depth. Local extension emerges due to strength heterogeneities and a misalignment of faults and the overall stress field in an area where regional tectonics are dominated by strike-slip motion. Furthermore, we reveal a crustal thinning and thickening pattern that intensifies with surface process efficiency. Along-strike deformation is linked through coupled crustal flow driven by gravitational potential energy which is opposed by deposition at the releasing bend and enhanced by erosion around the restraining bend. Due to the generic nature of our models, our results provide templates for the evolution of fault bends worldwide.

How to cite: Brune, S., Heckenbach, E. L., Glerum, A. C., Granot, R., Hamiel, Y., Sobolev, S. V., and Neuharth, D.: 3D interaction of tectonics with surface processes explains fault network evolution of the Dead Sea Fault, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15751, https://doi.org/10.5194/egusphere-egu24-15751, 2024.

Distinct Mountain–Basin coupling systems were formed during the expansion of the Tibetan Plateau into the surrounding low elevation regions in the north, northeast and east. In this study, we focus on the topographic features of the Bogda Mountains–Southern Junggar Basin coupling system on the north of the Tibeau Plateau, which influenced by the N-S orthogonal shortening caused by the uplift of the Tibetan Plateau and northward propagation of deformation away from the India-Asia collision zone. We mainly quantify the influence of uplift of the Tibetan Plateau on the formation of the Bogda Mountains–Junggar Basin coupling system by fluvial geomorphologic analysis based on the digital elevation model analysis and the optically stimulated luminescence (OSL) dating on the Dalongkou river terraces on the northern slope of Bogda Mountains. Together, these morphological analyses show that the high normalized steepness index (k_sn) and knickpoints mainly distributed in the western Bogda Mountains. The normalized steepness index (k_sn) gradually decreased from west to east, which indicated that the tectonic activity of the western Bogda Mountains is higher. The compiled low-temperature thermochronology data of the Bogda Mountains show a younging trend from west to east, which indicates that the western Bogda uplift started earlier than in eastern Bogda. The difference of the χ values on both sides of the Bogda Mountains is similar, which means the drainage divide of the Bogda Mountains is stable. There are five river terraces distributed on both side of the Dalongkou River. The optically stimulated luminescence (OSL) dating results show that the ages of the T2 river terrace, T3 river terrace, T4 river terrace of the Dalongkou river are 6.2±1.3 ka, 13.1±1.7 ka, and 14.2±2.5 ka, respectively. The incision rate of the Dalongkou river increases upstream from ~1.22 mm/yr close to the southern Junggar Basin, to ~2.1 mm/yr, and to ~6.33 mm/yr in front of the higher Bogda Mountains, which means that the uplift rate of the Dalongkou river increases upstream. We propose a model of upbending of central Bogda Mts. by ongoing Holocene folding, with an inflection point close to the southern boundary to the Junggar Basin. By comparing the geomorphological features of the Bogda Mountains with the North Tianshan Mountains, we conclude that the tectonic uplift intensity gradually decreased from the North Tianshan Mountains to the Bogda Mountain, as well as the gradual accelerated uplift rate of the Bogda Mountains, are influenced by the N-S orthogonal shortening caused by the uplift of the Tibetan Plateau, which is gradually decreasing from west to east.

How to cite: Duan, M., Neubauer, F., Robl, J., Zhou, X., and Liebl, M.: The Northward Expansion of the Tibetan Plateau: Topographic Evidence from the Bogda Mountains—Junggar Basin Coupling system, Northwest China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13770, https://doi.org/10.5194/egusphere-egu24-13770, 2024.

The study of rock-uplift variations in time and space can provide insights into the processes driving the topographic evolution of mountain belts. The Apennine mountain chain of Italy, one of the more recently developed mountain belts in the Mediterranean region, has undergone a strong Quaternary rock-uplift phase, particularly in the north-central sector, which has shaped the present-day topography. It has long been recognized that drainage systems can record temporal and spatial variations in rock-uplift rates. Specifically, in detachment-limited systems with simple settings (e.g., no significant variations in drainage area over time, and catchments mostly draining perpendicular to regional structures), river profiles can be inverted to reconstruct their history of rock uplift. In this study, we present linear inversions of river profiles from 28 catchments along the eastern flank of the northern-central Apennines. These results are calibrated to infer rock-uplift rates by estimating the value of an erodibility parameter (K) from short-term incision rates and catchment-averaged erosion rates obtained from cosmogenic-nuclide data. Different approaches with constant and variable K have been applied to produce the rock-uplift model that best fits independent geochronological constraints about the uplift of the Apennine belt. Our findings suggest a spatially and temporally variable rock-uplift event that started around 2.5 to 3 Ma, following the last compressional orogenic phase and coinciding with the onset of extension. Furthermore, this rock-uplift pulse migrated southward at a rate of approximately 115 km/Myr. The highest rock-uplift rates (higher than 1.2 km/Myr) are observed in the region encompassing the highest Apennine massifs, such as the Laga Massif and the Gran Sasso Range. These results align with previous studies on Apennine paleoelevations, and they are consistent with numerical models and field evidence from other regions exhibiting rapid rock-uplift pulses and the migration of uplift related to slab break-off. Our results support the hypothesis of a break-off of the Adria slab under the central Apennines and its southward propagation over the last few million years.

How to cite: Racano, S., van der Beek, P., Faccenna, C., Buleo Tebar, V., Cosentino, D., and Schildgen, T.: Tectonic driving mechanism of Quaternary rock-uplift and topographic evolution in the northern-central Apennines from linear inversion of the drainage system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8880, https://doi.org/10.5194/egusphere-egu24-8880, 2024.

In recent years, numerous studies focused on reconstructing the surface uplift history of the Central Anatolian Plateau (CAP) and the associated driving mechanisms such as slab breakoff, removal of lithospheric mantle, or crustal thickening (e.g. McPhee et al., 2021). The CAP forms the westward portion of the Turkish−Iranian plateau and has mostly been above sea level since ca. 41 Ma (Okay et al., 2020). Most of its present-day topography, featuring mean elevations of ca. 1.0-1.5 km, however, has been shaped since the Late Miocene (e.g. Meijers et al., 2018; Schildgen et al., 2012a,b). Perhaps the most spectacular discovery is the recognition of 2 km of surface uplift of a portion of the southern plateau margin, the Tauride Mountains, since ca. 0.5 Ma (Öğretmen et al., 2018).

Here, we provide stable isotope paleoaltimetry estimates for the Late Miocene for the southern CAP margin. The method is based on the inverse relationship between the oxygen isotopic composition (δ¹⁸O) of meteoric waters and elevation. We therefore contrast the δ¹⁸O values of age−equivalent low and (potential) high elevation soil carbonates (the δ−δ method; Mulch, 2016) from central Anatolia with published Anatolian and Aegean soil carbonate δ¹⁸O values (Böhme et al., 2017; Meijers et al., 2018; Quade et al., 1994). Our results reveal a low (ca. 0.5 km) orographic barrier between the Aegean and Mediterranean coastlines and central Anatolia at ca. 10 Ma, which increased to an elevation of ca. 1 km by ca. 8−6 Ma. This trend in increasing surface elevations during the Late Miocene is in agreement with stable isotope−derived paleoelevation estimates from Anatolian lacustrine carbonate records (Meijers et al., 2018). Given proposed post−0.5 Ma surface uplift of the southernmost plateau margin (Öğretmen et al., 2018), our results imply a phase of significant local subsidence bracketed between the latest Miocene and ca. 0.5 Ma. From the Pliocene onward, we also observe long-term trends toward higher δ¹⁸O values in soil carbonate data sets from the Aegean Sea and CAP region, which indicate increased aridification and possibly seasonality of rainfall in the region since the Pliocene. Additionally, our ‘modern’ soil carbonate records from central Anatolia underestimate the elevation of the modern Tauride orographic barrier (ca. 2.2 ± 0.5 km) at the southern plateau margin by ca. 0.5 to 1.0 km (non−linear vs. linear lapse rate, respectively). We attribute this underestimation to the mixing in of higher δ¹⁸O atmospheric moisture derived from the Black Sea compared to atmospheric moisture derived from the Mediterranean Sea during spring and early summer, a signal that is likely incorporated into soil carbonates that form at the onset of the dry summer season. Although atmospheric moisture derived from the Black Sea yields lower δ¹⁸O values than Mediterranean atmospheric moisture at sea level (Schemmel et al., 2013), the former undergoes less distillation across the significantly lower northern plateau margin (the Pontide Mountains). The presently observed mixing of Black Sea and Mediterranean Sea moisture sources might have also led to an underestimation of southern orographic barrier elevations in the geologic past.

How to cite: Meijers, M. J. M., Mikes, T., Rojay, B., Aydar, E., Çubukçu, H. E., Wagner, T., and Mulch, A.: Central Anatolian (Turkey) and Aegean (Greece) soil carbonate δ18O values reveal Late Miocene surface uplift of the southern plateau margin and post−Miocene aridification of the northeastern Mediterranean region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10486, https://doi.org/10.5194/egusphere-egu24-10486, 2024.

Mass transport deposits or olistostromes, carrying large-sized blocks or olistoliths, are related to active and passive margin tectonics. Information on how they are produced is critical to understanding the tectonically driven topographic dynamics in the source areas, and the tectonic evolution of sedimentary basins and their shoulders. The geological record of these mass transport deposits is commonly well preserved onshore, in orogenic regions where continental margins uplift was influenced by the gradual movement of continents.

The Iberian Massif is one of the World’s key areas for studying ancient orogenies, like the Late Paleozoic Variscan belt, to understanding the formation of olistostromes, and developing provenance studies on such complex tectonic fold and thrust belts. Structural relations between the basement and overlying Mississippian synorogenic marine basins were recently examined in the lower plate (Gondwana side) of the Variscan collisional orogeny in Iberia. The stratigraphy of these Variscan synorogenic basins is quite complex and includes: a) sedimentary melánges (e.g., related to submarine mudflows and turbidites) that carried or were formed by different-sized blocks of different age metamorphic, volcanic, siliciclastic and carbonated rocks derived from the nearby pre-Mississippian basement; b) partially or completely dismantled Devonian and/or Mississippian carbonate platforms; and c) syn-sedimentary bimodal calc-alkaline volcanism. Geochronology data show that Mississippian sedimentation and volcanism occurred simultaneously with regional high temperature-low pressure metamorphism, associated with the formation of gneiss domes, bounded by extensional shear zones and faults, during crustal thinning and plutons emplacement. Mapping of shear zones and faults on the Iberian Variscan basement provided crucial information for better comprehending Mississippian synorogenic basin architecture. Our study demonstrates that there is a spatial and temporal relationship between the generation of olistostromes (including large olistoliths) and the development of first-order extensional structures in the pre-Mississippian basement.

Given that the collision between Laurussia and Gondwana had already occurred, it seems that these Mississippian synorogenic basins were not formed in a foreland, backarc, or forearc setting related to the subduction of the Rheic oceanic lithosphere, and thus, other geodynamic hypotheses need to be set. Two tectonic models have been discussed to explain the occurrence of a significant thermal anomaly beneath the lower plate (Gondwana side) and the formation of the Mississippian synorogenic basins in Iberia: Model A) considers that the roll-back of the lower plate was responsible for the formation of an orogenic plateau, the lateral flow of partially molten orogenic roots, and peel-back tectonics, after the subduction of the Rheic Oceanic lithosphere under the upper plate (Laurussia side) and the subsequent continental collision. In this case, the Mississippian synorogenic basins would be of peel-back type; Model B) invokes the subduction of the Paleotethys oceanic lithosphere beneath the Variscan collisional orogen, and the Mississippian synorogenic basins would be of backarc type but developed later than the Rheic Ocean closure.

This work was supported by FCT I.P./MCTES (Portugal) through national funds (PIDDAC) – UIDB/50019/2020 (https://doi.org/10.54499/UIDB/50019/2020), UIDP/50019/2020 (https://doi.org/10.54499/UIDP/50019/2020), LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020), DL57/2016/CP1479/CT0030 (https://doi.org/10.54499/DL57/2016/CP1479/CT0030), FCT/UIDB/ 04683/2020-ICT and by the Spanish Agency of Science and Technology MCIN/AEI/10.13039/501100011033 and TED2021- 130440B-I00

How to cite: Dias da Silva, Í., Pereira, M. F., González-Clavijo, E., Silva, J. B., and Steel Hart, L.: Variscan olistostromes and the geological history they tell… unraveling the tectonic evolution of the Pangea supercontinent , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9089, https://doi.org/10.5194/egusphere-egu24-9089, 2024.

In contrast to the mountainous topography and high relief of the eastern Tauern window, the adjacent Nock Mountains (Gurktal Alps, Austria) are characterized by hilly topography, lower relief and rounded summits with elevations of ca. 2000 m. Although the unusual landforms in the Nock Mountains have long been recognized (Hejl, 1997; Frisch et al., 2000, and references therein), little is known about rates of landscape evolution in this area, which was deglaciated ~15 ka ago (Wölfler et al., 2022). Here we present a new set of 16 catchment-wide erosion rates from the Nock Mountains derived from cosmogenic ¹⁰Be concentrations in stream-sediment samples. Samples from 10 major streams that drain the Nock Mountains toward the Mur-Mürz valley, the Katschberg-Lieser valley and the Drau valley range between ~130 and ~300 mm/ka. Smaller subcatchments with low relief located in the upper part of the larger catchments erode at lower rates between ~80 and ~160 mm/ka. A comparison between ¹⁰Be-derived erosion rates and exhumation rates obtained from low-temperature thermochronology and thermokinematic modelling reveals that short-term and long-term erosion rates are remarkably similar. In the central Nock Mountains, ¹⁰Be-derived erosion rates of 110-160 mm/ka are similar to the long-term exhumation rate of ~160 m/Ma since ~34 Ma (Wölfler et al., 2023). The southern Nock Mountains (Millstatt Complex) show higher short-term erosion rates of 170-300 mm/ka and also a higher long-term exhumation rate of ~270 m/Ma since 18 Ma (Wölfler et al., 2023). The similarity between short-term and long-term erosion rates suggests that the pace of erosion in the Nock Mountains did not change significantly during the late Cenozoic. A comparison of our data with ¹⁰Be erosion rates from the eastern Tauern Window (>500 m/Ma) and the Lavanttal Alps (<125 m/Ma) (Dixon et al., 2016; Delunel et al., 2021), which are located west and east of the Nock Mountains, respectively, reveals that erosion rates in the Eastern Alps decrease from west to east.

• References
• Delunel R, Schlunegger F, Valla PG, Dixon J, Glotzbach C et al. (2020) Earth-Sci. Rev. 211:103407.
• Dixon JL, von Blanckenburg F, Stüwe K, Christl M (2016) Earth Surf. Dyn. 4:895–909.
• Frisch W, Székely B, Kuhlemann J, Dunkl I (2000) Zeitschr. f. Geomorph. 44:103–138.
• Hejl E (1997) Tectonophysics 272:159–173.
• Wölfler A, Hampel A, Dielforder A, Hetzel R, Glotzbach C (2022) J. Quat. Sci. 37:677-687.
• Wölfler A, Wolff R, Hampel A, Hetzel R, Dunkl I (2023) Tectonics 42:e2022TC007698.

How to cite: Hampel, A., Wölfler, A., Wolff, R., and Hetzel, R.: 10Be-derived catchment-wide erosion rates from the Nock Mountains (Gurktal Alps, Austria): comparison with thermochronological data and implications for landscape evolution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1362, https://doi.org/10.5194/egusphere-egu24-1362, 2024.

The Vosges massif is a mid-altitude mountain range located northeast of France. It extends latitudinally for 250 km north of the Alps and is characterized by topographic, geological and geomorphological north-south and east-west gradients. In the south, the exhumed Paleozoic basement culminates at about 1400 m asl while in the north, river valleys incise Mesozoic sandstones with summits ranging between 400 and 700 m asl. The relief is intricately linked to the Eocene-Oligocene formation of the Rhine graben and the Mio-Pliocene deformation of the Alpine foreland. The present-day slow deformation rates in the Rhine graben, coupled with the region’s moderate seismicity characterized predominantly by strike-slip mechanisms, raise questions about the current driving forces behind the Vosges’ topographic evolution.

The evolution of drainage divides provides a window into the complex interrelations among tectonic forces, surface erosion processes and climatic influences that contribute to shaping a mountain range. In this study, we combine morphometric and cosmogenic nuclides (¹⁰Be and ²⁶Al) analyses to assess the migration of the Vosges’ main drainage divide. Gilbert’s metrics (elevation, relief and gradient) alongside χ-index reveal a strong eastward gradient across the divide suggesting a migration away from the Rhine graben margin. To provide a quantification of this migration, a dataset of in-situ cosmogenic nuclides whose concentrations are erosion-dependent has been measured in samples collected across various segments of the divide. Cosmogenic nuclide analysis reveals a robust set of ¹⁰Be/²⁶Al ratios falling within the steady-state denudation curve and denudation rates, ranging from 30 to 90 mm/kyr in the south and 40 to 70 mm/kyr in the north. Notably, both regions display an eastward trend in denudation, corroborating the gradient observed in the morphometric analysis.  A geometric approach was used to translate cross-differences in denudation rates and topographic gradients into migration rates of the main drainage divide, showing a westward shift of 20-70 mm/kyr in the south and 3-30 mm/kyr in the north.

Expanding our analysis, we examined the correlation between the calculated denudation rates and the hilltop curvatures derived from high-resolution DEMs (1m). A relation appears in the south, whereas no relationship has been found in the north, suggesting additional complexities in controlling morphogenetic processes. This finding allows us to use hilltop curvature as a proxy for denudation rates, particularly within mono-lithologic soil-mantled basins along the southern Vosges drainage divide. These insights offer a valuable conceptual framework for constraining numerical simulations at the mountain range scale aimed at unravelling the external forces that shape the highest Vosges relief.

How to cite: Mathieux, B., van der Woerd, J., Chabaux, F., Steer, P., Carcaillet, J., and Perrone, T.: What controls the migration rate of divides? Insights from morphometry and 10Be and 26Al cosmogenic nuclides analysis applied to the Vosges massif, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11203, https://doi.org/10.5194/egusphere-egu24-11203, 2024.

Assessing the Quaternary topographic stability of western Europe middle mountains characterized by low tectonic activity remains challenging. We suggest to tackle this question in the Vosges – Upper Rhine Graben system where elevation reach up to 1400 m asl. This study is focused on the Strengbach catchment, that flows from the Vosges massif towards the Rhine graben, upstream of Ribeauvillé in the central Vosges. The catchment reaches 29 sq.km between 500 to 1200 m elevation. Morphometric analysis of the main trunk and tributaries is performed to constrain the areas of topographic disequilibrium along the valleys (knickpoints). ¹⁰Be cosmogenic isotope analysis in river sediments from various sites in the catchment is used to constrain the migration rates of these topographic instabilities at the millennial scale.

The morphometric analysis performed in the Strengbach catchment (catchment topography - χ-elevation profiles) provide evidence of relic topographic surfaces upstream of a 2 km-long convex knick-zone located at about 700 m. Below this zone, the catchment is deeply incised and ramified with knick-points in the tributaries at about 500 m. Above the knick-zone, fluvial incision is reduced with a high-standing knickpoint at about 950 m marking the upper section of the Strengbach stream. ¹⁰Be denudation rates points to relatively small variations along the main trunk upstream (36 ± 2 - 44 ± 3 mm/ka), while denudation rates derived from the tributaries range from 38 ± 2 mm/ka to 75 ± 5 mm/ka. We show that these variations are primarily controlled by topographic and lithologic factors, namely the presence of sandstones in the sub-catchments, characterized by higher erodibility than crystalline rocks. The ¹⁰Be cosmogenic isotope concentrations in sediments from both upstream and downstream of the knickpoints, and in the tributaries, constrain at first order the migration rate of the knickpoints along the river profile and the retreat rate of sandstone cliffs upstream some tributaries. Migration rates on the order of 100-200 m/Ma suggest that at the millennial scale, the topography is relatively stable. These data will be used to discuss the source of topographic disequilibrium present in the catchments.

How to cite: van der Woerd, J., Moreno Martin, D. S., di Chiara Roupert, R., Mathieux, B., Perrone, T., Rixhon, G., Merchel, S., Mériaux, A.-S., and Chabaux, F.: Relief stability of western Europe middle mountains from morphometry and 10Be denudation rates: the Strengbach catchment case in the central Vosges massif, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12254, https://doi.org/10.5194/egusphere-egu24-12254, 2024.