The Himalayan-Tibetan Plateau presents an exemplary setting to explore the intricate interactions among tectonics, erosion, and climate. Since achieving its elevated stature in the Miocene, the plateau's landscape has undergone significant transformation, largely influenced by several major rivers. The Yarlung Tsangpo River, the largest river on the plateau, has been instrumental in this geomorphic evolution. Throughout the Neogene and Quaternary periods, this river has facilitated the extensive removal and transportation of massive rock volumes from the plateau into the southern Himalayas. Consequently, it has profoundly affected the patterns and intensities of erosion and uplift within the orogenic system, contributed to the reorganization of river networks, and influenced sedimentary processes in the adjacent foreland basin. Nevertheless, the specifics of river erosion evolution process in southeast Tibet and its driving factors remain a subject of considerable debate.

In this study, we present an in-depth analysis of both long- and short-term denudation processes in southeast Tibet, particularly along the Yarlung Tsangpo River. The long-term denudation history is elucidated through exhumation rate simulations derived from published low-temperature thermochronological data. Near the hanging wall of the Woka normal fault (upstream), the data indicates an average exhumation rate of 0.23 km/Ma, predominantly from samples older than 10 Ma. In contrast, the footwall experienced an initial rapid exhumation phase around 10.25 ± 0.81 Ma, with rates approximating 0.53 km/ myr. This rate was comparatively steady at 0.31 ± 0.01 km/ myr further from the fault. Subsequently, at 7.12 ± 0.36 myr, the exhumation rate increased to 0.42 ± 0.02 km/myr. Post 5 Ma, rapid exhumation, reaching rates of 0.57 ± 0.05 km/ myr, was confined to the Jiacha Gorge, continuing up to ~1 Ma as indicated by AHe dating. Short-term erosion processes were assessed through millennium-scale catchment erosion rates, determined by cosmogenic nuclide analyses of river sediments. A sample from the hanging wall of the Woka normal fault indicated a catchment-wide erosion rate of 19.9 m/myr. Conversely, samples from outside the Jiacha Gorge, including two from main river tributaries and two from secondary tributaries, demonstrated significantly higher erosion rates, ranging from 47.5 to 67.3 m/myr.

Subsequently, we employed 3D thermo-kinematic modeling to reconstruct the region's topography as it appeared approximately 15 million years ago, integrating both long-term exhumation and short-term erosion rates. The model suggests the formation of a peneplain in southern Tibet around 15 Ma, after notable uplift in the early Miocene and substantial exhumation between 20 and 15 Ma. The drainage patterns during this period in southern Tibet likely differed markedly from the present, as the eastward-flowing Yarlung Tsangpo River had not yet formed. It is hypothesized that the river flowed directly towards the Himalayan foreland until around 6 Ma. At this time, the river channel was altered through capture by the Jiacha Gorge, redirecting its flow eastward.

How to cite: Shen, T., Wang, G., and Miao, S.: Multi-stage river incision processes since 15 Ma and the formation of the Yarlung Tsangpo River in the southeast Tibet, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2715, https://doi.org/10.5194/egusphere-egu24-2715, 2024.

Base level fall on a tributary is genetically related to its trunk channel incision, and analysis of tributaries thus provides information of the trunk channel evolution history. In the middle Yellow River, for example, several integration processes were proposed and should be consistent with river terrace data from the trunk channel. We investigate the rates and spatiotemporal variations of incision along the Jinshan Gorge in the middle Yellow River with dated strath terraces from its tributaries. The incision rate for six tributaries along the Jinshan Gorge is constrained using mapped and dated terraces. By comparing terraces of similar age, we find generally decreasing incision rates from the confluence with the trunk river to upstream within a tributary in the southern Jinshan Gorge. Decreasing incision rates are also observed among tributaries from south to north along the gorge. The results independently confirm the spatial pattern from “pseudo-terraces” derived from channel profile modeling. This interpretation reinforces the previous proposal that paleo-lake regressions in the Weihe Graben or integration with the Hetao Graben are unlikely to have been responsible for recent incision. An estimation method with terrace data within a tributary of erodibility coefficient, K, a crucial parameter for river profile inversion analysis, is also provided. K is recalibrated to be 1.03 10^-5 m^0.3/a with all terrace data. With an assemblage of published terrace data along the Jinshan Gorge, we suggest a re-examination of published terrace ages, which may help unravel the mysterious evolution history of the middle Yellow River.

How to cite: Zhong, Y., Picotti, V., Xiong, J., Willett, S., Schmidt, C., and King, G.: Increasing fluvial incision rate in the southern Jinshan Gorge from tributary terraces and river network analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5314, https://doi.org/10.5194/egusphere-egu24-5314, 2024.

Stream networks are striking expressions of how Earth’s hydraulic cycle shapes topography, yet the degree to which different geomorphological processes are visible in their ramified structure remains debated. Here we analyzed 18,030 river networks across the contiguous United States as mapped by the high resolution National Hydrographic Dataset, measuring the Tokunaga parameter c, which characterizes the degree of side-branching, in order to quantify the stream networks' topologies. We find that stream networks with more side branches tend to occur in wetter climates while channel networks in arid regions are less "feathered". As side branches tend to be steeper than the main channel, the aridity-induced dependence of slope ratio identified in recent studies may indicate inherent topological differences between stream networks in arid and humid regions. Such climatic signatures in the planform morphology of stream networks may help to better understand landscape evolution on the continental scale, and may also hold clues for the climatic history of other planetary bodies such as Mars or Titan.

How to cite: Li, M., Seybold, H., Fu, X., Wu, B., and Kirchner, J.: Climatic controls on the stream network topology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6811, https://doi.org/10.5194/egusphere-egu24-6811, 2024.

Drainage systems are highly sensitive to landform changes, and their formation and evolution history are of great significance for understanding regional tectonic-climatic processes and ecological environmental changes. Since the Cenozoic, the uplift and expansion of the Tibetan Plateau have profoundly influenced the landforms and drainage patterns in its surrounding area. The Qinling-Daba Mountains are located on the northeastern margin of the Tibetan Plateau, and the Han River, as the largest tributary of the Yangtze River, originates from the southern flank of the Qinling Mountains and flows from west to east between the Qinling and Daba Mountains, whose evolution history may document abundant clues of the expansion of the Tibetan Plateau and regional tectonic-climatic responses. Previous studies suggested that a significant river reorganization event may have occurred in the upper reaches of the Han River. However, the timing and mechanism are still vague. In this study, the evolution history of the upper reaches of the Han River is reconstructed through terrace mapping, paleocurrent measurements, K-feldspar Pb isotope provenance analysis, and quartz electron spin resonance (ESR) dating. Combined with the fault kinematic analyses, it is believed that before 0.4 Ma, the Paleo-Han River flowed directly eastward along the Ankang Basin. Between 0.4-0.15 Ma, the continuous left-lateral strike-slip movement along the Ankang Fault resulted in vertical uplift at its compressional bend and caused the Han River to flow southward and bypass into the Daba Mountains. This river evolution event within the Qinling region reflects the adjustment process of the peripheral water systems and landforms under the influence of the expansion of the Tibetan Plateau.

How to cite: Ju, D. and Yang, Z.: Pleistocene drainage reorganization of the upper reaches of the Han River and its tectonic significance, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7041, https://doi.org/10.5194/egusphere-egu24-7041, 2024.

Fluvial erosion of small mountain belts is widely represented as a wave of upstream migration of knickpoints, starting from a stationary boundary of a high topography created by increased rock uplift rates. However, mountain belts such as the Tibetan Plateau and the central Andes are large, and fluvial erosion remains poorly constrained when orogens expand in width with their boundaries continuously advancing towards the foreland. Here we propose a simple analytical solution for a laterally expanding orogen dominated by fluvial erosion, and apply it to the propagation of Eastern Tibet where the plateau margin is characterized by widespread low-relief surfaces incised by steep river valleys. Our analytical solution is based on the assumption that the topography of Eastern Tibet was built by high uplift rates located in a belt along the plateau margins migrating outwards during plateau growth, as well as carved by erosion of large rivers originating from the interior of the plateau. We validate our analytical solution by comparing it to numerical models and various types of data from five large rivers in Eastern Tibet (Salween, Mekong, Yangtze, Yalong, and Dadu Rivers). The results show that the models with optimized parameters are generally consistent with the observed river-profile morphologies, exhumation magnitudes, and low-temperature thermochronometric ages. We also tested whether the observations on topography and exhumation could also be explained by a period of headward erosion and plateau retreat, the consequence of an early formation of the Tibetan Plateau. By testing various fluvial erodibilities and model durations, we could not reproduce the observed topographies, river profiles, and exhumation magnitudes. The tested model also predicts an increase in thermochronometric ages from the center to the margin of the plateau, opposite to the observed trend of ages. Our results thus show that the long-term fluvial erosion in Eastern Tibet features mainly a downstream migration of high erosion rates, which is fundamentally different from the headward erosion of most of small mountain rivers and a major plateau margin retreat. The characteristics described by our simple analytical solution may represent a common pattern of outward growing mountains and plateaus in tectonically active regions on Earth.

How to cite: Yuan, X., Jiao, R., Liu-Zeng, J., Dupont-Nivet, G., Wolf, S., and Shen, X.: Downstream versus upstream propagation of fluvial erosion in orogenic plateaus: Example of the eastern Tibetan Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7762, https://doi.org/10.5194/egusphere-egu24-7762, 2024.

During the Cenozoic, the formation of the Andean Cordillera had a profound effect on the drainage evolution in the South America continent. The load of the Andes induced the bending of the lithosphere, creating foreland basins adjacent to the cordillera. Additionally, an increase in orographic precipitation along the eastern flank of the Andes amplified the erosion of the cordillera and the sedimentation rate in the foreland and other interior basins. As a result, the drainage pattern changed from parallel to the cordillera to a system perpendicular to the orogen. This led to the development of the Amazon drainage system in northern South America and guided the formation of the present Paraguay-Paraná Basin in southern South America. Concurrently, dynamic topography induced by the subduction of the Nazca plate under the western margin of the continent created long-wavelength topographic perturbations throughout the continent, partially modulating the generation of accommodation space in interior sedimentary basins and allowing intermittent marine incursions in lowland regions. In this work, we present this complex evolution based on numerical models dedicated to simulating the tectono-sedimentary evolution of the entire South America continent, coupling surface processes, lithospheric flexure, sea-level oscillations, and dynamic topography. This project represents an expansion of the works developed in our research group, previously focused only on the drainage dynamics of northern South America.

How to cite: Sacek, V. and Bicudo, T.: Drainage dynamics of the entire South American continent during the Andean Orogeny: Results from tectono-sedimentary numerical models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11931, https://doi.org/10.5194/egusphere-egu24-11931, 2024.

The large-scale reorganization of drainage patterns is one of the most enigmatic events in the landscape history of Central Europe. In particular, the rivers Main and Neckar show a reversal of the flow direction from southeast to northwest. Historically, this has been interpreted as a consequence of the subsidence of the Upper Rhine Graben (URG) and the subsequent lowering of the base level. However, the high uplift rates along the shoulders of the URG, which suggest an increased southeastward tilt, raise questions. This prompts the investigation of alternative uplift patterns contributing to the observed river reversals.

This study uses a new version of the landscape evolution model TTLEM and river analyses with TopoToolbox to investigate the potential role of large-scale lithospheric folding resulting from the collision of the Alps. Our research challenges the conventional narrative by examining whether such folding could be a driving force behind the enigmatic flow reversals in the Main and Neckar rivers.

During the transition from the Cretaceous to the Paleocene, a dome-shaped exhumation event in Europe led to the establishment of a radial river network originating in higher regions. Some rivers still have their original flow directions, such as the Wörnitz and the Brenz, or the Neckar, which now flows in the opposite direction. In southern Germany, a network of rivers flowed in a southward or southeastward direction. The Eocene marked the beginning of the formation of the URG, accompanied by a marked uplift of the Graben shoulders and a tilting of southern Germany to the east-southeast. During this period, the flow directions of the rivers remained constant, and the sinking URG initially failed to extend its drainage basin beyond the graben shoulders.

The pivotal moment in the redirection of the rivers has been evident since the Miocene when lithospheric folding occurs parallel to the Alpine front. This previously unnoticed event highlights a crucial link between the collision of the Alps and the redirection of the Main and Neckar rivers. Our findings shed light on the complex interplay of tectonic forces, landscape evolution, and river dynamics, challenging existing paradigms and contributing to a deeper understanding of the geomorphic history of Central Europe.

How to cite: Rau, M., Schwanghart, W., and Krautblatter, M.: A landscape evolution model of how uplift has shaped drainage patterns in Central Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18699, https://doi.org/10.5194/egusphere-egu24-18699, 2024.

The lateral movement of Earth’s crust through tectonic advection plays an important role in shaping topography in many active orogens worldwide. Numerical modelling and select field studies have shown that tectonic advection can alter topography and thereby create asymmetric drainage divides. Divide migration typically occurs opposite to the direction of tectonic advection, however, in many mountain belts, the wedge-tip propagation towards the foreland outpaces the rate of convergence, in which case the direction of topographic asymmetry should be reversed. 

We combine geomorphic and geodetic analyses with numerical models to test whether topographic asymmetry in the Longmenshan region of Southeast Tibet is dominated by advection of the crust from the ongoing India-Eurasia collision, movement of river base-level with the propagation of the thrust front into the Sichuan Basin, or other tectonic and climatic factors. We measure the magnitude and direction of drainage divide asymmetry using geomorphic metrics and compare these to horizontal GNSS velocities, which measure tectonic advection and shortening relative to the stable Sichuan Basin block. Geologic studies estimate that wedge-tip propagation toward the Sichuan Basin has been negligible since ~5-10 Ma.

Our results show that drainage divide asymmetries in the Longmenshan and Bayankala tectonic blocks indicate a dominantly northwest divide migration direction relative to the underlying rock. This is opposite to the dominantly southeast-pointing GNSS rates and suggests that within-wedge shortening and southward surface advection are more important than wedge-tip propagation. These findings also indicate that topography in the Longmenshan and Bayankala blocks has already adjusted to the current kinematics. Inconsistencies in the signal can be explained by localized deformation and uplift from faulting and other small-scale transient adjustments in the river network, such as those caused by stream captures. We compare these results to a series of numerical model scenarios with varying advection and wedge-tip propagation velocities to discern the relative influence of tectonic advection and thrust-front dynamics on the region’s topography. Our study highlights the critical role tectonic advection plays in shaping topography on the Southeast Tibetan Plateau and it provides a comparative framework for distinguishing the relative rates of advection and wedge-tip propagation.

How to cite: Gelwick, K., Wang, Y., Metzger, S., Huppert, K., Yang, R., and Willett, S.: Tectonic advection controls drainage divide asymmetry patterns in the Longmenshan, SE Tibet, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10973, https://doi.org/10.5194/egusphere-egu24-10973, 2024.

Climate contrasts across drainage divides, such as orographic precipitation, are ubiquitous in mountain ranges, and as a result, mountain topography is often asymmetric. Asymmetric glaciation arising from climate gradients across divides can cause topographic asymmetry that is potentially different from fluvial landscapes, causing divide instability during glacial-interglacial cycles. In this study, we quantified topographic asymmetry caused by asymmetric glaciation and assessed its sensitivity to different climate scenarios. Using an analytical model of a steady-state glacial profile, we find that the degree of topographic asymmetry is primarily controlled by differences in the Equilibrium Line Altitude (ELA) across the divide. When the ELA differences are caused by precipitation variations across the divide, glacial topography exhibits greater asymmetry than fluvial topography. These results suggest that glacial erosion responds differently to the same climate asymmetry from fluvial erosion, and therefore, intermittent glaciations may have promoted drainage reorganization and landscape transience in glaciated mountain ranges. Preliminary model results indicate that the rate of divide migration caused by asymmetric glaciation is several millimeters per year and the timescale of migration is several million years.

How to cite: Lai, J. and Huppert, K.: Climate-driven topographic asymmetry enhanced by glaciers: Implication for divide stability in glacial landscapes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7438, https://doi.org/10.5194/egusphere-egu24-7438, 2024.

How to cite: Harries, R., Reaney, S., Aguilar, G., and Kirstein, L.: Climate storminess as a driver of surface processes and a limiting factor for topographic responses to rock uplift, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20314, https://doi.org/10.5194/egusphere-egu24-20314, 2024.

How to cite: Haag, M., Schoenbohm, L., Jess, S., Augusto Sommer, C., and Endrizzi, G.: Lithological influence on bedrock incision and transience: Insights from the Aparados da Serra Escarpment, southeast Brazil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-682, https://doi.org/10.5194/egusphere-egu24-682, 2024.

Earthquake-triggered landslides pose significant hazards and their long-term effects can radically reshape the local physiography but also may generate cascading risks. Indeed, a landslide could dam the river, having for consequence the formation of an upstream lake, which in turn makes the dam unstable, leading to cataclysmic flooding in the case of sudden failure. The Naryn River is one of the most important rivers in the Western Tien Shan, and major changes in its dynamics could have a significant economic impact in Central Asia and lead to political tensions over water management. Our study focuses on the Beshkiol paleo-landslide (>10km³), one of the largest in Central Asia, an overlooked hazard along the Naryn River.
Through a multi-disciplinary approach that combines detailed geomorphological, sedimentological and chronological (luminescence, cosmogenic and radiocarbon) analysis over a study area more than 130 km-long, we determined the different phases that affected the evolution of this landslide from the late Pleistocene to the late Holocene. First of all, two lacustrine sequences have been identified in the Naryn Basin, illustrating two successive periods of river damming and a lake outburst flooding. The triggering of the Beshkiol landslide occurred ~52 ka ago, led to the damming of the Naryn River and the formation of an 80 km-long lake upstream. Our chronological constraints highlight a residence time of 36,000 years, one of the longest ever documented in the world for a natural dammed-lake. This lake then drained in a cataclysmic event around 15 ka, which most likely led to the flash flooding of the downstream basin of the Naryn River (Kazarman Basin), as evidenced by very high energy deposits identified upstream of the landslide. However, shortly afterwards (less than 1,500 years), the foot of landslide was reactivated, causing the formation of a second lake, with a residence time estimated at ~7,600 years. This period was followed by a gradual emptying, and a phase of erosion that shaped the present landscape. Our results highlight that cascading events took place over the last 50,000 years and show complex interactions between the Naryn River and the largest landslide in Central Asia. Today, this landslide is categorized as inactive, but in view of the large volumes of material that can be reactivated by earthquakes or changes in precipitation, it is necessary to take this hazard into account as several thousand people living in the region could be impacted

How to cite: julie, L., magali, R., alexis, N., maxime, H., mathieu, S., erkin, R., sultan, B., kanatbek, A., jules, F., vincent, R., and lionel, S.: Repeated failures of the giant Beshkiol landslide and its impact on the long-term Naryn Basin flooding, Kyrgyz Tien Shan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-193, https://doi.org/10.5194/egusphere-egu24-193, 2024.

The hyper-extended Eastern Sardinian margin is due to the eastward migration of the Appennine-Calabria subduction zone, creating the Neogene back-arc Tyrrhenian Basin. This area was affected by strong erosion during the Messinian Salinity Crisis (MSC, 5.97 - 5.33 Ma) on the continental shelf and slope leading to a major discontinuity, known as the Messinian Erosion Surface (MES), constituting, therefore, a remarkable stratigraphic marker. It is also a powerful paleo-topographic marker of the MSC times and can be used as a marker of the deformation during Plio-Quaternary times. The end of the rifting phase in the Eastern Sardinian margin is dated during the Tortonian (11.63 - 7.25 Ma) attested by the occurrence of a relatively thick syn- and post-rift sequence pre-dating the MES.

The “METYSS 4” cruise led to the acquisition of more than 2,000 km of very high-resolution (VHR) seismic reflection data, following a dense grid, on the Eastern Sardinian continental shelf and slope, which has been little explored until now. Seismic interpretation allowed for mapping the major erosion surface, the MES, across the continental shelf and slope. At the base of the PQ sequence, the MSC paleo-topography highlights a hydrographic paleo-network identical to the current one and a general progradation of the shelf-break toward the east during the Plio-Quaternary. In the southern part of the study area, several east-dipping normal faults, oriented N-S, significantly shift the MES (between 5 and 55 m; assuming sound wave velocity of 1700 m/s in Plio-Quaternary sediments). The MES is tilted toward the fault and is covered by Plio-Quaternary deposits, which display a fan-shaped geometry (eg. 50 m thick on the hanging wall). These NS-trend faults are cross-cut by E-W trending messinian canyon and this fault pattern is also observed on the other flank of the canyon. The along-strike geomorphological analysis of canyons reveals the occurrence of knickpoints (slope breaks) coinciding with the front of the two fault patterns. Moreover, the shifts in water depth of most knickpoints are at the same order of amplitude than fault offsets (ie. 10 to 50 m). These geomorphologic markers reinforce the hypothesis that the fault activity is recent (ie. less than 5 Ma). We interpret these observations as markers of a recent reactivation of the structures inherited from the rift in the western part of the Tyrrhenian Sea.

How to cite: Sylvain, R., Gaullier, V., Chanier, F., Watremez, L., Caroir, F., Graveleau, F., Lofi, J., Maillard, A., Sage, F., Thinon, I., and Travan, G.: Geomorphological evolution of the Eastern Sardinian Margin (Western Tyrrhenian) from the Messinian to the Plio-Quaternary: New evidence for post-rift deformation from bathymetric and seismic data., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9308, https://doi.org/10.5194/egusphere-egu24-9308, 2024.

The Central Range, the Iberian Chain and the Toledo Mountains in central Iberia were built during the Paleogene and Neogene alpine deformation, in response to shortening and thickening of the crust. The Cenozoic Madrid Basin in central Iberia was filled under endorheic conditions, fed by clastic sediments supplied from these mountains. This sediment influx led to the accumulation of over 3km of clastic sediments, primarily occurring during the Oligocene and early Miocene epochs. Presently, the river network, connected to the Atlantic Ocean, has carved into the sedimentary basin, resulting in an incision exceeding 200 meters.

The most recent endorheic lacustrine sediments in the center of the Basin are commonly believed to have been deposited during the late Miocene (~6 Ma). Recently published dating of alluvial pediments in the northwestern part of the Basin using the cosmogenic nuclide method suggests that the basin experienced a semi-endorheic period lasting around 3 Ma (~6.4 Ma to >2.4 Ma). It is proposed that the onset of glacial/interglacial oscillations at ~3.35 Ma (M2 event) would have driven the overspilling of the closed sedimentary Basin, establishing its connection to the Atlantic River network (Karampaglidis et al., 2020).

We present a new stratigraphic framework based on a new magnetostratigraphic analysis of the Plio-Quaternary deposits located in the center of the Madrid sedimentary Basin, incorporating new paleontological data and absolute U-Pb carbonate dating. Our findings indicate lacustrine endorheic conditions prevailed at least until 2.6 Ma. Moreover, on top of the lacustrine deposits, an accumulation of clastic deposits and carbonated paleosoils persisted until 1.7+-0.3 Ma. Modeling the transient incision within the Basin revealed a subsequent wave of incision propagating from the South to the North along the Central System mountains. Consequently, the onset of river incision appears to be more recent than previously acknowledged and unrelated to the onset of Quaternary climate oscillations. The long-wavelength deformation and the southward tilting of the youngest lacustrine deposits, combined with the age of the overlying paleosoils, suggest a mantle-driven surface uplift of Central Iberia during the last 1.7+-0.3 Ma. Previous studies suggested that regional surface uplift and the building of the Iberian Meseta began either at 20 Ma or after 3 Ma, depending on the methodology employed. The observed incision history in the Madrid Basin aligns with the latter estimation and even suggests a more recent age for a mantle-related surface uplift and the opening of the Cenozoic Madrid Basin.

Reference:

Karampaglidis, T., Benito-Calvo, A., Rodés, A., Braucher, R., Pérez-González, A., Pares, J., Stuart, F., Di Nicola, L., and Bourles, D., 2020, Pliocene endorheic-exhoreic drainage transition of the Cenozoic Madrid Basin (Central Spain): Global and Planetary Change, v. 194, p. 103295.

How to cite: Montes, M., Babault, J., Beamud, E., Garcés, M., Beranoaguirre, A., and Pelaez-Campomanes, P.: Quaternary intraplate surface uplift and opening of the Cenozoic Madrid Basin (Central Iberia), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16382, https://doi.org/10.5194/egusphere-egu24-16382, 2024.

Plio-Quaternary global climate changes had major impacts on landscape dynamics and relief evolution worldwide. The Quaternary onset and intensification of the glaciation in the European Alps greatly reshaped the mountainous reliefs with deep glacial carving of the modern main valley systems. Quantifying this climate forcing on the long-term relief evolution is challenging because of the poor preservation of the surface geomorphic markers in a context of strong landscape rejuvenation. Previous studies have shown that a major incision phase occurred for the Aare and upper Rhône valleys (Switzerland) since the mid-Pleistocene transition (onset of the 100-ka glacial-interglacial cycles). But the dynamics of this incision phase remains poorly constrained in both time and space across the Alpine realms. Moreover, the Pliocene to Lower Pleistocene Alpine relief dynamics is still largely unknown. To fill this current knowledge gap, we study cave systems in karst environments which are widespread in the frontal part of the western to central Alps. Karst network development and associated cave sediment records are closely coupled with valley evolution and can be preserved for timescales of million years. They are therefore ideal proxies for quantifying long-term relief dynamics.

This study focuses on 3 cave systems nearby the Isere valley (western French Alps) and 1 cave system at the head of the Sarine valley (central Swiss Alps). We apply a multi-method approach that combines 3D analysis of the cave networks with geochronological data on both the detrital sediments (²⁶Al/¹⁰Be burial dating and paleomagnetism) and speleothems (U/Th and U/Pb dating).

Our results show a significant development of the major Alpine cave systems during the Pliocene, in agreement with previous studies. The abandonment of the perched networks around the Isère valley highlights a first incision phase in the frontal part of the Alps at the Pliocene-Quaternary transition. The apparently later abandonment of the cave system in the upper Sarine valley (~1.8 Ma) suggests an apparent lag in the incision onset for the upper Alpine watersheds. The main incision phase of the Isère valley to its modern base level (i.e. not considering the overdeepened section) took place in the early Middle Pleistocene from ~800 ka up to 450 ka, therefore occurring over only few glacial cycles. Our results imply thus a rapid response time (i.e. few 100 ka) of the major Alpine glacial valleys physiography to the Plio-Quaternary climatic forcing.

How to cite: Mai Yung Sen, V., Valla, P., Rolland, Y., Jaillet, S., Robert, X., Borreguero, M., Crouzet, C., Carcaillet, J., Pons-Branchu, E., Bruguier, O., Boutin-Paradis, N., Malet, E., and Gauchon, C.: Quaternary incision dynamics of the western to central Alpine valleys from cave systems investigations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18199, https://doi.org/10.5194/egusphere-egu24-18199, 2024.

Estimating exhumation rates on Pleistocene-Holocene time scales presents a challenge due to the scarcity of suitable low-temperature thermochronometers. Apatite helium (AHe) dating is unable to precisely differentiate cooling ages <1 Ma and whilst optically stimulated luminescence (OSL) thermochronometry resolves younger ages (10⁴-10⁵ years timescale), it is limited in regions with lower exhumation rates (<2-3 mm/yr). These restrictions limit our ability to accurately study exhumation rates on such time scales, thus hindering our understanding of the implications of tectonics, climate, and hydrology. To address this challenge and gain insights into the dynamics of rapid exhumation, we conducted our study in the Sutlej River valley (northwest Indian Himalaya), which features a prominent river anticline with exceptionally high exhumation rates locally reaching up to 12 mm/yr (OSL data from a previous study). For this purpose, we collected 10 samples, including 5 from a 2200 m vertical profile in the Sutlej valley, and 5 from the main tributaries. The new OSL analysis of these samples reveals high exhumation rates at lower altitudes (<2500 m), ranging from 6-8 mm/yr, 350 m above the river, and from 3-5 mm/yr, 720 m above the river. Furthermore, OSL ages of samples from lower elevations along the tributaries were not saturated, also pointing to rapid exhumation in these areas. In contrast, all samples from higher elevations (>2500 m) reach field saturation, indicating lower average exhumation rates that cannot be recorded using OSL thermochronometry. Although the vertical profile data exhibit a significant increase in exhumation rates over the past 200 kyr, this region lacks glaciated landscapes, suggesting a feedback loop within the river anticline. The river incision promotes the development of the anticline, which, in turn, amplifies the river incision, leading to accelerated exhumation over time. By demonstrating the importance of the interplay between river incision and anticline development in driving the progression of exhumation rates in the Sutlej River region, this study offers a new perspective on Late Pleistocene exhumation rates in the Himalayas.

How to cite: Genge, M., Bouscary, C., Webb, A., King, G., Adeoti, B., Ganbat, A., and Vlaha, D.: Unraveling rapid exhumation: Insights into the increase of exhumation rates in the Sutlej River anticline (NW Indian Himalaya) over the last 200 kyr., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10477, https://doi.org/10.5194/egusphere-egu24-10477, 2024.

Around the Nanga Parbat-Haramosh massif in the west and the Namche Barwa massif in the east, the Himalayan orogen exhibits an abrupt strike change from roughly E-W to N-S, forming two structural syntaxes. Each syntaxis is drained by a major trans-orogenic river system: the Indus and Ganges-Brahmaputra, respectively. The syntaxial massifs record rapid exhumation rates (up to c. 10 mm/a), together with Plio-Pleistocene mineral (re)crystallisation and cooling ages (Bracciali et al, 2016; Crowley et al., 2009; Zeitler et al., 1993). The Namche Barwa massif supplies c. 65-74% of Brahmaputra bedload (Enkelman et al., 2011; Dong et al., 2023). In contrast, the Nanga Parbat massif supplies c. 10% of modern Indus bedload, which instead is dominantly sourced from the East Karakoram (Clift et al, 2022).

We present detrital rutile and zircon U-Pb data from the Indus fan, sampled by IODP expedition 355 and ODP leg 117. These data record abrupt increases in the proportion of sediment sourced from the Nanga Parbat massif between c. 8-6 Ma and again at c. 2 Ma, coherent with bedrock studies (Crowley et al., 2009; Zeitler et al., 1993). The Nanga Parbat massif then dominates sediment supply until c. 1.5-0.6 Ma, followed by an abrupt switch to East Karakoram sourcing.

The East Karakoram includes some of Earth’s highest peaks, and largest extra-polar glaciers. Therefore, a provocative possibility is that the jump in erosion focus was driven by the switch from c. 41 ka, obliquity-dominated, to 100 kyr, eccentricity-dominated orbital forcing (the Mid-Pleistocene Transition). This transition occurred at c. 1 Ma (Clark et al., 2006), and could have driven enhanced glacially-mediated erosion in the east Karakoram, outpacing Nanga Parbat exhumation. Approximately synchronous increases in exhumation rate are also documented at Nanga Parbat-Haramosh massif, and the Namche Barwa massif (Guevara et al., 2022; Govin et al., 2020; King et al., 2016;).   

Bracciali, L., et al., 2016, Earth-Sci. Rev., 160, 350-358, doi: 10.1016/j.earscirev.2016.07.010; Clark, P., et al., 2006, Quat. Sci. Rev., 25, 3150-3184, 10.1016/j.quascirev.2006.07.008;; Clift, P., et al., 2022, Earth Plan. Sci. Lett., 600, 117873, 10.1016/j.epsl.2022.117873; Crowley, J., et al., 2009, Earth Plan. Sci. Lett., 288, 408-420, doi: 10.1016/j.epsl.2009.09.044; Dong, X., et al., 2023, Basin Res., 35, 2193–2216, doi: 10.1111/bre.12795; Enkelman, E., et al., 2011, Earth Plan. Sci. Lett., 307, 323-333, 10.1016/j.epsl.2011.05.004; Govin, G., et al., 2020, Geology, 48, 1139-1143, doi: 10.1130/G47720.1; Guevara, V., et al., 2022, Science Advances, 8, eabm2689, 10.1126/sciadv.abm2689;King, G., et al., 2016, Science, 353, 800-804, doi: 10.1126/science.aaf2637; Zeitler, P., et al., 1993, Geology, 21, 347-350, doi: 10.1130/0091-7613(1993)021<0347:SAMARD>2.3.CO;2

How to cite: Mark, C., Clift, P., Paolucci, C., Alizai, A., and Garzanti, E.: Enhanced exhumation in the East Karakoram during themid-Pleistocene climate transition: A detrital provenance assessment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11893, https://doi.org/10.5194/egusphere-egu24-11893, 2024.

Mountain building through continent-continent collision is typically accommodated by crustal thickening and creates topography as a consequence of isostatic compensation. Precipitation-fueled erosion, in-turn, counteracts orogen growth and provides a feedback-loop between tectonics, surface processes, and climate. Climate on Earth varies on different timescales and with variable dominant periodicity. Orbital forcings, e.g. Milankovitch cycles, change climate with periods up to in the order of 1e5 years, while internal “tectonic” forcings change climate on longer timescales in the order of (several) Myrs. The feedback between tectonics and climate-fueled erosion raises the question: How do collisional mountain belts respond to climatic variations on Earth? Here, we use numerical coupled tectonic-surface processes models to explore the influence of periodic climatic variations on collisional mountain building on Earth, specifically focusing on the evolution of sediment flux and topography. Our results from the coupled numerical models are compared to and supported by a simple analytical solution. We find that climatic forcings with a short period have a small effect on orogen height (Gain G < 0.1), that is lagging by 1/4 phase, while the effect on the sediment flux is in phase and strong (G ≈ 1). These results are independent of orogen type and expected to be observable in orogens limited in height by crustal strength or erosional efficiency. Climatic forcings with a long period result in a low gain in sediment flux (G < 0.3), that is lagging by up to 1/4 phase. The effect on topography is in phase and with a high gain of up to G ≈ 1. However, the effects of long-period forcings are not well expressed in strength-limited orogens and can primarily by observed in erosion-limited orogens. Comparing our modelling results with typical tectonic and surface processes timescales of orogens on Earth shows that variations in erosional efficiency due to orbital forcings, i.e. Milankovitch cycles, are likely detectable in the sedimentary record, while it is challenging to disentangle the autogenic dynamics of mountain building and periodic long-term climatic forcings.

How to cite: Wolf, S. G., Braun, J., and Huismans, R. S.: Periodic climatic variations during collisional orogenesis – insights from coupled tectonic-surface-process models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15067, https://doi.org/10.5194/egusphere-egu24-15067, 2024.

Since the Earth’s topography is shaped by both tectonic and climatic processes, measuring land surface elevation variations through time is of critical importance for the investigation of the multiple interactions between mountain building (orogenic) processes and long-term climate change. With a total surface area of over 5 million km², an average elevation of 5000 m and 14 peaks over 8000 m, the Tibetan Plateau (TP) and adjacent Himalaya are particularly well suited to this research, as many models attempt to explain the growth of these high elevation regions in the context of the continental collision between India and Asia and their feedback on the Asian climate. However, the evolution of surface elevation (paleoaltimetry), whilst essential, is still elusive in the Himalaya. A number of published paleoaltimetric data hinges on the relationship between the stable isotopic composition of precipitation (δ¹⁸O and δD) and altitude. However, these methods, based on the stable isotopic composition of carbonates and phylosilicates, do not provide both δ¹⁸O and δD values and involve the use of an isotope exchange equation to calculate the composition of paleoprecipitation. To avoid such calculation, we use a method developed at LGL-TPE, which directly measure the isotopic composition (δ¹⁸O and δD) of paleoprecipitation trapped in fluid inclusions of hydrothermal quartz veins.

We measured the δ¹⁸O and δD of fluid inclusions in quartz veins within the Main Central Thrust shear zone in the Jajarkot klippe (Central Himalaya, Nepal). The δ¹⁸O of fluid inclusions varies between -3.69‰ and -9.01‰ and the δD between -43.11‰ and -74.24‰, which are consistent with meteoric water compositions. Stable isotope analysis were coupled with Ar-Ar geochronology on hydrothermal white micas that co-crystallized with quartz and indicates an age of 24.7 ± 0.2 Ma for vein formation. Taken together, these data allow us to calculate a mean elevation of the Central Himalaya of 2771 +286/-403 m at the end of the Oligocene, a period for which no previous paleoaltimetric data are available. Although already significant 25 Myr ago, the mean elevation of the Central Himalaya was nevertheless lower than the average elevation of the present topography (~5000 m), which formed at least ~16 Myr ago (e.g., Gébelin et al., 2013, Melis et al., 2023). Collectively, our data as well as previous paleoaltimetric studies provide a valuable contribution to the assessment of deformation models for the Himalayan range.

How to cite: Melis, R., Mahéo, G., Gardien, V., Leloup, P.-H., Scaillet, S., Jame, P., and Bonjour, E.: Late oligocene elevation of the Himalaya recorded by O and H isotopes of fluid inclusions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-426, https://doi.org/10.5194/egusphere-egu24-426, 2024.

The Jordan Rift Valley (JRV) is a depression produced by the active Dead Sea Transform (DST), separating the Sinai subplate and the Arabian Plate. Its beginning is related to the late Miocene (~6 Ma), when sinistral displacement of the DST gained an extensional component, thus accentuating the subsidence of the JRV. This shift is recorded by Messinian basalt flows that cover JRV eastern slopes (Zerqa Ma, Mujib, and Tafila basalts; 6–3.4 Ma) and the Cover basalt (5.8–3.6 Ma) in the Galilee region. Sediments from the Sedom Lagoon since ~12 Ma suggests that the JRV was already a shallow depression connected with the Mediterranean Sea, which at the early Pliocene (5–4 Ma) lost permanently this connection due to the uplift of the JRV flanks. More information about geomorphology and drainage pattern of the region during the Late Miocene is limited to information available along the western side of the JRV, including the fluvial/lacustrine Hazeva Fm (~20–6.4 Ma) in the Arava region and lacustrine/marine formations in the lower Galilee (~17–5 Ma). Here we discuss the implications of Zarqa Valley geomorphological features and its volcano-sedimentary infill to the Miocene evolution of the JRV. The Zarqa Valley is carved into Cretaceous/Paleogene bedrocks at the Eastern Flank of the JRV, and it hosts a perennial water drainage system flowing westward to the Jordan River. The oldest dated filling of the Zarqa Valley is represented by a series of late Miocene lava flows, named collectively as “Lower Basalt” (LB), spanning 5.82 to 5.51 Ma. It records the existence of a pre-existing valley in the late Miocene, with already at least 300 m of incision, observed by the difference of the base of the LB and the bedrock summits surrounding the valley. The LB outcrops ca. 40 km east of JRV axis and its thickness increases eastward to more than 100 m. W-NW paleocurrent data in conglomerates underlying the LB indicate that the Zarqa River maintained the same flow towards the JRV since the Late Miocene. The occurrence of the LB in the Zarqa Valley is synchronous with the dramatic sea level fall of Messinian Salinity Crisis (MSC, 5.97–5.33 Ma), when the Sedom Lagoon lost temporarily the connection to the Mediterranean Sea. Opposite to what is observed throughout the Mediterranean Sea, where rivers underwent a profound incision phase, the Zarqa Valley experienced aggradation of conglomerates and thick basalt flows. We propose that this is an indication that Sedom Lagoon acted as local base level of an endorheic drainage by the time when the MSC started, possibly with an increasing water table, necessary to produce the accumulation space to account for the Zarqa Valley deposition. We hypothesize that a highstand of the base level in the JRV during the MSC can be explained by a favorable climate and several stream capture in the Levant that caused rivers to migrate to the endorheic drainage of the Sedom Lagoon.

How to cite: Scardia, G., Cerqueira, J. C., Ladeira, F., Parenti, F., and Neves, W.: Late Miocene evolution of Jordan Rift Valley recorded on its eastern flank, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9632, https://doi.org/10.5194/egusphere-egu24-9632, 2024.

Changes in precipitation can drive major shifts in stratigraphy and fold-thrust belt behavior. We investigate the stratigraphic and orogenic response to pronounced climatic warming during the Middle Miocene Climatic Optimum (ca. 17-14 Ma) in the southern Central Andes.  New and compiled stratigraphic and geochronologic data come from depocenters at ~25-35°S; these basins would have occupied both high and low elevation positions during the middle Miocene. Regionally ubiquitous eolianite deposition from ca. 22-17 Ma supports arid conditions on the eastern flank of the Central Andes preceding the Middle Miocene Climatic Optimum. Eolian facies are replaced by fluvial-lacustrine strata near the onset of the Middle Miocene Climatic Optimum over 1000 km along-strike. These results support a change from arid to more seasonal and humid conditions during the Middle Miocene Climatic Optimum. New climate models also support increased seasonality and moisture availability on the eastern flank of the Andes during the Middle Miocene Climatic Optimum, which we attribute to intensification of the South American Monsoon. We compare our results with published sequentially restored, regional cross-sections to explore linkages between the climatic shift and orogenic growth. A more seasonal climate should drive increased erosion, which in turn should drive the wedge into sub-critical state as predicted by critical taper theory.

How to cite: George, S. W. M., Carrapa, B., DeCelles, P. G., Jepson, G., Nadoya, H., Tabor, C., Howlett, C. J., Ronemus, C. B., Clementz, M. T., and Schoenbohm, L.: The stratigraphic and orogenic response to the Middle Miocene Climatic Optimum in the southern Central Andes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8974, https://doi.org/10.5194/egusphere-egu24-8974, 2024.

During the last decade there has been an increase in the study of transient topography because it gives information about surface uplift history. The onset of transient topography forms after a gain in potential energy which leads to the creation of slopes at the outlet of catchment. It is followed by a wave of transient erosion that propagates upstream along the main river, then across tributaries, and from the tributaries to the hillslopes. Records of incision history such as topographic data and landform dating can be gathered into inversion schemes to reconstruct base-level fall and uplift history. In this study, we employ a reversible jump Markov chain Monte Carlo Bayesian algorithm to perform an inversion of topographic data, landform dates, and erosion rates in order to unravel surface uplift history. By adopting a probabilistic approach, we generate an ensemble of solutions that comprise various combinations of model parameters. This methodology enables us to estimate uncertainties in the timing and amount of changes in uplift rates. In the forward model we use the non-linear analytical solutions of the stream power incision model that states that incision I = KA^mSⁿ is simply a function of S, the local channel gradient, and A, drainage area above that point and K incapsulates climatic conditions, geometrical and hydraulic characteristics of the stream, bedrock resistance to erosion. Our inversion is constrained by new river-sands ¹⁰Be cosmogenic nuclide data, and by incision rates derived from river terraces from the literature. Millennial scale erosion rates and topographic metrics helps us to calibrate the empirical scaling parameters of the stream power incision law. We apply our model to the Atlantic rivers draining NW Iberia where canyons are incised in low-relief erosional surfaces that developed in the last 100 Ma. We show that the transient topography is compatible with a regional late Cenozoic uplift of several hundreds of meters, most likely in response to a mantle-related continental-scale uplift.

How to cite: Babault, J., Figueiredo, P., Owen, L. A., Fullea, J., Negredo, A., Arroucau, P., Bodet, L., Charco, M., Van Den Driessche, J., and Caffee, M.: Mantle-related late Cenozoic surface uplift in NW Iberia revealed by 10Be cosmogenic nuclide dating and non-linear river profile inversion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11613, https://doi.org/10.5194/egusphere-egu24-11613, 2024.

It is widely recognized that the topography of the Earth's surface records coupling between tectonics, climate and surface processes. However, the relative contributions of tectonic and climatic drivers to the observed topography, rates and patterns of erosion remain poorly constrained in many mountain regions. The Terskey Range, located in the Kyrgyz Tian Shan, is an ideal natural laboratory to investigate this question because of its well-documented structure, kinematics and denudation history. Cenozoic deformation of the Terskey Range is mainly characterised by southward tilting associated with thrusting along the Main Terskey Fault; this fault delimits the mountain range to the north. Tilting can be reconstructed using relict low-relief surfaces that have undergone minimal Cenozoic erosion. Slip along the Main Terskey Fault initiated in the early Miocene and accelerated at around 10 Ma. A comparison between short- and long-term denudation rates suggests a significant increase during the Quaternary, which has been linked to glaciation of the range. The geomorphology of the range, with deeply incised, highly concave main valleys contrasting to less incised and concave minor valleys, suggests significant but variable ice dynamics.

We focus here on the reanalysis of published low-temperature thermochronology data (apatite fission-track, apatite and zircon (U-Th-Sm)/He) of two elevation transects from the glacially affected Barskoon Valley, one of the main valleys draining the Terskey Range to the north. We collected three new valley-bottom samples from the Barskoon Valley to better constrain differential erosion along the valley, with the aim to discriminate between tectonic, fluvial and glacial drivers of valley incision. Inverse thermal-history modelling of the elevation profiles, combining new and existing data, indicates a significant increase in exhumation rate since around 3 Ma in the northern transect. We suggest that this signal records the initiation of efficient glacial erosion in Terskey Range. Future studies will include higher resolution 4He/3He thermochronology of the valley-bottom samples and inversion of the preglacial topographic relief using thermal-kinematic Pecube.

How to cite: Gong, L., van der Beek, P., Sobel, E., Schildgen, T., Mariotti, A., Bernard, M., and Glodny, J.: Late Cenozoic deformation and glacial imprint on the Terskey Range, Kyrgyzstan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14635, https://doi.org/10.5194/egusphere-egu24-14635, 2024.

Rifted margins include the Earth’s most voluminous sediment accumulation, host important energy and natural resources providing a rich archive for global environmental changes. However, revealing the deep structure within rifted basins is challenging, because their deep part is commonly vogue in seismic images and their structure is complex because it is usually affected by several deformation phases that occurred during their long history. The Levant Basin is a good example for a deep Tethyan basin that formed alongside Gondwana breakup. Unlike many Tethyan basins that were eroded and/or severely deformed during the Alpine orogeny, the Levant Basin has preserved a thick (>15 km), long-lived (>250 Myr), and continuous sedimentary record providing a world-class archive to study the role of post-rift subsidence and sediment supply on depocenter evolution.

We synthesize regional seismic interpretations from previous studies utilizing thousands of kilometers of seismic lines and tens of wells in a unified dataset. By applying a low pass post-stack filtering on 2D seismic reflection surveys covering the Israeli economic water, we improved the imaging of the deeper reflectors and enabled the distinction of the deep units, which otherwise appeared blurred at conventional industry processed data. Based on thickness analysis, we identify the syn-rift to post rift transition. The regional seismic horizon marking this transition is tied to dated horizons in wells providing a concrete age constraint of pre- 163 Ma (end of Callovian) for the end of rifting, which was previously debated. In addition, we show that rifting comprises at least two phases, which are equivalent to three extensional phases documented onshore: Permian, Mid-Late Triassic and Early-Mid Jurassic.

Analysis of 11-thickness maps showcase the 250 Myr evolution of sedimentary filling, opening a discussion about the parameters that controlled depocenter migration in relation to tectonic subsidence and sediment supply. We distinguish between periods during which near margin accumulation dominated versus periods during which more sediments accumulated in the deep basin. We explain these variations in light of sediment sources in surrounding continents and paths of transport. Marginal accumulation periods (syn-rift, early post-rift, and Pliocene-Quaternary) represents dominance of shallow biogenic and nearby terrestrial (silisiclastic) sources, whereas, deep basin accumulation periods represent sediment supply that was either provided from the water column (pelagic micro- and nano-fossils, Santonian to Mid-Eocene), or transported mostly from Africa with minimal accumulation along the Levant margin (during the Late-Eocene to Miocene).

How to cite: Sagy, Y. and Gvirtzman, Z.: Interplay between early rifting and sedimentary filling along 250 Myr of a long-lived Tethys remnant: the Levant Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20660, https://doi.org/10.5194/egusphere-egu24-20660, 2024.

To comprehend the evolution of a landscape in response to intraplate crustal deformation over long timescales, it is necessary to investigate the interactions between tectonics, climate, and lithology. Isolating the role of each factor gives rise to a better understanding of landscape evolution. In this respect, the Talesh Mountains, which are a prominent tectonic range in the NW of the Iranian Plateau and formed by compressional stresses owing to the Arabia-Eurasia continental collision, provide a unique case study to explore the interplay between tectonics and surface processes. The range shows a transient landscape resulting from a combination of several tectonic events from the Eocene to the Pliocene, rainfall variability and rock strength contrasts. To date, the main governing agents of the present-day architecture of landscape have not been fully studied. We therefore combined geomorphological field surveys with quantitative analyses of the regional topography, geomorphology and stability of the main drainage divide, stream profile analysis and denudation rates using meteoric ¹⁰Be to decipher the surface deformation, uplift mechanism and drainage divide evolution. Additionally, an inverse modelling of the river longitudinal profiles was performed to reconstruct the base level fall history of the region, providing insights into the timing of the rock uplift rates and geodynamics of the NW margin of the Iranian plateau. Our results document contrasting erosion rates ranging from ⁓ 100 to 400 m/Myr, with lower values in the more arid plateau interior, and higher values on the wetter plateau exterior. These rates correlated well with topographic metrics. The spatial pattern of erosion rates showed that the drainage networks of the eastern flank of the range, and along the plateau margin are eroding about twice as fast as those in the plateau interior. These contrasting erosion rates triggered the divide migration towards the plateau interior. Our inverse modelling of river longitudinal profiles of the plateau exterior indicated a progressive increase in the relative rock-uplift rates which reached its peak to ⁓0.5 mm/yr from ⁓5 to 3 Ma. For these documented uplift rates there are two different processes: (i) a kilometer-scale base level drop of Caspian Sea driven by eustasy and changes in regional tectonics, and (ii) localized thrusting and rock uplift along the eastern flank of the range. The combined effect of these processes results in a significant relative base level fall. This event accelerated the bedrock river incision in the Talesh Mts. The differences in erosion rate across the divide are indicative of a long-wavelength morphological disequilibrium and landscape transience in response to asymmetric uplift and feedback of surface processes driven by climate together with lithological characteristics.

How to cite: Moumeni, M., Della Seta, M., Delchiaro, M., Ballato, P., Nozaem, R., Tikhomirov, D., Christl, M., and Egli, M.: Uplift history and landscape evolution along the northwest margin of the Iranian Plateau (Talesh Mountains) in the Arabian–Eurasian collision zone, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-714, https://doi.org/10.5194/egusphere-egu24-714, 2024.

Conventional low-temperature thermochronology can resolve cooling typically associated with ~2 – 6 km of erosion. Lower magnitudes of erosion produced by surface processes and climatic variations are often difficult to quantify. Here, we apply a new, low-temperature thermochronometer (closure temperature <50 – 25 °C), monazite fission-track (MFT), to the Catalina-Rincon metamorphic core complex, Arizona, USA which has a well-constrained tectonic and paleoclimatic history. In the Catalina-Rincon, traditional low-temperature thermochronology (apatite and zircon fission-track and apatite and zircon [U-Th-Sm]/He) record timing of cooling related to metamorphic core complex detachment faulting and subsequent Basin and Range normal faulting (26 – 20 Ma and 15 – 12 Ma, respectively). We collected two monazite fission-track age-elevation profiles across southwestern and northeastern extent of the Catalina-Rincon. The southwestern profile (~ 1000 m relief) records a Plio-Pleistocene age-elevation trend, with older ages at higher elevations (4.5 – 1.5 Ma). Whereas the northwestern profile (~ 500 m) records a late Miocene-Pleistocene age-elevation trend, also with older ages at higher elevations (8.1 – 2.0 Ma). Across the two profiles these ages do not correlate with known tectonic activity in the region, they are consistent with Pliocene intensification of the North American Monsoon. However, such a low closure temperature could suggest that fission-tracks in monazite are not stable at surface temperatures and lie in the partial annealing zone.  Despite this concern, we attribute Plio-Pleistocene thermochronometric ages to record climate-enhanced erosion during a known period of enhanced precipitation. These results suggest that MFT has potential for dating low-magnitude erosion associated with climate and relief-forming processes.

How to cite: Jepson, G., Carrapa, B., Jones, S., Kohn, B., Gleadow, A., George, S., Gehrels, G., Howlett, C., and Triantafyllou, A.: Monazite fission-track thermochronology as a possible proxy for low-magnitude erosion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5153, https://doi.org/10.5194/egusphere-egu24-5153, 2024.