To first order mountain belts grow by crustal thickening and gain their elevated topography through isostatic compensation. High and rising topography in turn modifies the global wind circulation system and is the main locus of (orographic) precipitation. The ensuing flow of water (or ice) redistributes mass through erosion and deposition, counteracts orogenic growth, shapes the appearance of the landscape, and most importantly provides a feedback-loop between surface processes and tectonics. However, it remains debated whether surface processes or lithospheric strength control mountain belt height, width, and longevity, reconciling high erosion rates observed for instance in Taiwan and New Zealand, low erosion rates in the Tibetan and Andean plateaus, and long-term survival of mountain belts for several 100s of million years. Here we use a tight coupling between a landscape evolution model (FastScape) and a thermo-mechanically coupled mantle-scale tectonic model (Fantom) to investigate mountain belt growth. Based on several end-member models and the new non-dimensional Beaumont number, Bm, we provide a quantitative measure of the interaction between surface processes and tectonics, and define three end-member orogen types: Type 1, non-steady state, strength controlled (Bm > 0.5); Type 2, flux steady state, strength controlled (Bm ≈ 0.4−0.5); and Type 3, flux steady state, erosion controlled (Bm < 0.4). Bm can be assessed without complex measurements or assumptions, but simply by knowing a mountain belt’s convergence rate, height, width, first order shortening distribution, and widening rate. In turn, assessing Bm of an orogen provides information about its crustal strength and average fluvial erodibility and gives insight into the factors controlling orogen type: In Himalaya-Tibet , high convergence rates dominate over efficient surface processes (Type 1), in the Central Andes low convergence rates dominate over low fluvial erosional efficiency (Type 1), efficient surface processes balance high convergence rates in Taiwan (likely Type 2), and surface processes dominate in the Southern Alps of New Zealand (Type 3). Our results provide a simple unifying framework quantifying how surface processes and tectonics control the evolution of topography of mountain belts on Earth.

How to cite: Wolf, S. G., Huismans, R. S., Braun, J., and Yuan, X.: The Beaumont number of mountain belts – quantifying the interaction between surface processes and tectonics during orogenesis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5283, https://doi.org/10.5194/egusphere-egu23-5283, 2023.

The Earth's surface topography reflects the long-term competition between tectonic and climate-driven surface processes. River erosion is a fundamental process that sets the base level for hillslope processes and drives landscape evolution. River profiles reflect external processes, such as tectonic uplift and climate, as well as intrinsic properties of the landscape, such as lithologic variations. River profiles respond to perturbations in these parameters through local changes in channel gradient, which are transmitted upstream of the river channel. River networks affected by these processes may eventually suffer drastic river captures and important drainage reorganization. As a result, river profiles can be used to extract the uplift histories of landscapes. Geochemical data with sensitivities to different time scales, such as thermochronological ages and cosmogenic nuclide concentrations, can be combined in numerical models with river profile analyses to identify governing relationships response for a landscape history. However, the estimation of a complete denudation record through time remains challenging, especially in landscapes where river capture and drainage reorganization have strongly perturbated the river system.

            In this study, we perform inverse modeling of river profiles and thermo- and geochronology data (i.e., low-temperature thermochronology and cosmogenic nuclides) to infer erosive parameters and the topographic history of different settings. The numerical model allows the prediction of river profiles, thermochronological ages (e.g., zircon fission tracks, apatite fission tracks and apatite helium ages), cosmogenic nuclide concentrations, and simplistic river captures. Variability in both rock uplift history and erodibility of different lithologies are accounted for. The model algorithm utilizes an efficient inverse modeling scheme "Simulation-Based Inference" to resolve unknown parameters such as uplift or erodibility of the different lithology. Results are presented from the Neckar catchment located in southwest Germany, which shows evidence for major river captures and drainage reorganization over the last ~10 Ma. Model results allow to reproduce the river profile and thermo-geochronological data of the Neckar catchment for specific uplift and erodibility. Moreover, early experiments indicate a better prediction of the observed data, and therefore, the parameters controlling the erosion rate, when considering river captures.

How to cite: Bernard, T., Glotzbach, C., Peifer, D., Neely, A., and Ehlers, T.: Estimation of erosion rate parameters from neural network inverse modeling of river profile and thermo-geochronology data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4903, https://doi.org/10.5194/egusphere-egu23-4903, 2023.

Drainage network systems are one of the more responsive elements to recent active tectonic from among all the topographic features. Their anomalies can be significant in areas with high relief energy or less noticeable where intense deposition rates might make capable tectonic signatures not visible. In addition, surface processes are even dominated by changes in climate. Since landscape evolution is the result of the combination of these elements, drainage network systems represent a key element for understanding the role and importance of different factors involved in the processes during Quaternary that have led to the formation of the current relief.

The study area comprises two different zones in Piedmont region (North-Western Italy): the Western Po Plain and the Langhe and Monferrato hills, both located in a complex tectonic framework at which a juxtaposition on a crustal scale between Alpine metamorphic Units and the Ligurian Units of the Apennines takes place. A multi-disciplinary approach is proposed combining geomorphology and geostatistics, with the aim of obtaining a better understanding and knowledge of various aspects of the Quaternary evolution of the area on a regional scale.

A morphometric analysis was carried out based on 5 m resolution DEM supported by geological and geomorphological field surveys. To assess the changes in the river network’s direction a quantitative geomorphic analysis of river pattern has been performed through Geographic Information System (GIS) and MATLAB® tools. Different parameters were calculated with the aim of detecting anomalies and the estimation of local uplift and different erosion rates.  Following the extraction of longitudinal river profiles, calculating Normalized Channel steepness index (K_sn) has been possible for assessing river incision, based on local channel slope, contributing drainage area and some other characteristics related to incision processes and basin hydrology. This step has also allowed the identification of knickpoints whose presence represent a deviation of steady-state streams condition and hence a transient phase of potentially landscape changes.  These anomalies are present whether they were produced by tectonic deformation or by different factors. In addition, a paleotopographic reconstructions of Pleistocene deposits have allowed the estimation of the thickness of the deposits and the reconstruction of the river patterns during this period.

Preliminary results have provided relevant evidence of potentially recent and important changes in the regional drainage network of Western Po Plain resulting from the combination of tectonic activity during the Early Pleistocene and the climatic variation from the Middle and Late Pleistocene.

How to cite: Buleo Tebar, V., Bonasera, M., Racano, S., and Fubelli, G.: Assessment of Quaternary variations of the drainage pattern through morphotectonic investigations in Piedmont (North-western Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5412, https://doi.org/10.5194/egusphere-egu23-5412, 2023.

The asymmetry of slope of the opposing inclinations of the Eastern Carpathians is a regularity that was recognised over 100 years ago (after Jahn 1992). It is particularly well visible in the Bieszczady Mountains, where the southern slope is steeper than the northern slope and the erosion base of the southern slope is 100 m lower than the erosion base of the northern slope. Previous studies have not exhausted the possibilities of characterising this asymmetry, and contemporary analyses make it possible to refine and verify the theses put forward by previous researchers.  The research is supported by the availability of relatively new sources of data from laser scanning of the Earth's surface, with much greater accuracy than ever before. These data are available for both the N-Polish and S-Slovakian slopes. Their analysis is enabled by modern tools and methods of Geographical Information Systems (GIS). The execution of all measurements and calculations will be automated and much more accurate compared to previous measurements on topographic maps.

The paper will present selected morphometric parameters to determine differences in relief under the influence of asymmetry in the erosion base. The selection of surface units for the analysis of asymmetry will be addressed. Preliminary results of morphometric analysis for mesoregions will be shown: Beskid Niski, Nízke Beskydy, Bieszczady, Poloniny.

How to cite: Derii, A.: Asymmetry of valley systems of the northern and southern slopes of the Flysch Carpathians in the light of geomorphometric analyses, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-997, https://doi.org/10.5194/egusphere-egu23-997, 2023.

The Transantarctic Mountains (TAM) form a >3000 km-long boundary between East and West Antarctica with extreme relief reaching to >4500 m in elevation. Proximity of the TAM to the Cretaceous/Paleogene West Antarctic Rift System (WARS) suggests a genetic relationship between development of the TAM and extension of West Antarctica. However, the details of this relationship remain elusive.

Here we present the results of a low-temperature thermochronology study in the central TAM combined with numerical modelling of the thermal-kinematic crustal evolution. Sampling was undertaken along the ~100 km long, ~40 km wide Byrd Outlet that cuts through the TAM. We focus on the results of apatite fission track (AFT) analysis of seventeen samples collected along two near-vertical transects. All of these samples yield AFT ages of ~80 Ma. Transect A, located 45 km from the mountain front, has nine ~80 Ma samples along >1500 m of near-vertical relief (580-2140 m asl). Transect B is located 70 km from the mountain front, with eight ~80 Ma old samples along 700 m of near-vertical relief (450 m to 1150 m asl).

These ~identical ages typically would be interpreted to indicate rapid cooling through the AFT partial annealing zone (PAZ; 120°C-60°C). However, inverse modeling (HeFTy) shows that the samples experienced slow cooling (~4°C/m.y.), with samples remaining within the AFT PAZ for 30-60 my. Thus, there appears to be an inherent contradiction between the instantaneous cooling at ~80 Ma and the very slow cooling. 

To explore this apparent contradiction we designed a finite-difference thermal-kinematic model to reconstruct the erosional/cooling history of the crust of the Byrd Outlet region. Successful simulations must predict three things: 1) a coherent 1500 m thick crustal section that passes through the AFT closure temperature (110°C) ± simultaneously (± 5my), 2) this crustal section then must remain in the AFT PAZ for greater than 15 my, and 3) the top of this crustal section is currently located 1300 m below the adjacent surface of the earth (below the current peak of Mt McClintock at 3490 asl).

Modeling results confirm that successful simulations must include rapid incision of a km’s-deep gorge and the associated ± instantaneous cooling of the crustal section, followed by 10’s of millions of years of regional erosion and slow cooling through the AFT PAZ.

These results provide constraints on the timing and mechanisms responsible for the uplift of the central TAM. Firstly, the region-wide 80 Ma ages reveals incision of high topography in the Cretaceous, ~coeval with development of the West Antarctic Rift System. Secondly, this development of high topography far inland from the mountain front is inconsistent with rift-flank uplift. Additionally, the deep incision indicates > 5 km of uplift, which exceeds the amount that could be reasonably assigned to just flexure plus crustal thickening or just flexure plus lithospheric 

How to cite: Huerta, A., Blythe, A., and Winberry, P.: Cretaceous Uplift of the Transantarctic Mountains-Not Due to Rift-Flank Uplift, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9778, https://doi.org/10.5194/egusphere-egu23-9778, 2023.

Lithological and morpho-tectonic settings are among the most important influencing factors in the development of landslide phenomena in terms of size, spatial distribution, and pattern, especially in tectonically active sectors.

In this work, a 1,460 km² wide portion of SE Apennines, the Daunia Mountains (Apulia region), has been investigated to produce a new geomorphological (historical) landslide inventory map. This area is characterised by low gradients and clay-rich flysch formations (late Cretaceous-Miocene) that have been deformed by contractional tectonics. Daunia Apennines are notoriously prone to landslides, and this new geomorphological historical landslide inventory map reported the presence of 17,437 landslides, with an average density of about 15.6 landslides per square kilometre, excluding lowlands plain. A preliminary analysis conducted for the entire area showed the main relationships between landslides and the different tectonic units. Here, a downscaling investigation is carried out, focusing on an area of approximately 370 km², where more detailed 1:50,000 geological data are available (Carta Geologica d’Italia, CARG project).

Investigation of landslide size, type and spatial distribution within the different lithologies, shows that smaller landslides tend to develop within the siliciclastic and turbiditic sedimentary succession belonging to the San Bartolomeo Formation. On the other hand, ancient landslides with larger and heterogeneous dimensions, develop in the flysch lithologies made up of reddish thin-bedded clays and silts, interbedded with calcarenites and calcilutites layers, belonging to the Flysch Rosso and Flysch di Faeto Formations. These formations constitute most of the external ridges of the Daunia Apennine, forming the Daunia tectonic unit, which is strongly affected by the Apennine frontal thrusts system.

Similarly to what was observed in other geological settings of the Italian territory, the spatial distribution of landslides appears to be linked to the main morpho-structural lineaments of the region, and especially the spatial pattern of the largest landslides seems both passively and actively controlled by tectonic forcing, which has determined lines of weakness along the slopes. Additionally, the presence of the Apennine frontal thrust also caused topographic growth with increased local relative relief that favoured the occurrence of large landslides.

Building on such analyses, the unprecedented detail of the new geomorphological landslide inventory map, which reports a relative age estimation of landslides, will also help defining a possible landscape evolution pattern starting from evidences of the oldest slope failures that were recognized. Future work will add absolute dating constraints to such evolution pattern hypotheses which will help understand and compare past trend of landslide occurrence to the present day morpho-climatic setting.

How to cite: Pisano, L., Ardizzone, F., Bucci, F., Cardinali, M., Fiorucci, F., Santangelo, M., and Zumpano, V.: Lithological and morpho-structural control on landslide distribution in the Daunia Apennines, Southern Italy., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2076, https://doi.org/10.5194/egusphere-egu23-2076, 2023.