We aim to better understand the overall source to sink system from eroding orogens to subsiding lacustrine or marine basins and their sedimentary infill. Advancing our understanding of these coupled systems requires an interdisciplinary approach. A major challenge lies in quantifying uplift, erosion, subsidence, and sedimentation, while distinguishing the respective roles of crustal deformation, mantle flow, and climate-driven processes—each acting across different spatial and temporal scales and often leaving overlapping signals in the geological record.
This session brings together comprehensive studies that integrate observational data (e.g., field studies, geophysical and well data, thermochronology), theoretical frameworks, and both analogue and numerical modelling. Our goal is to foster dialogue between disciplines and highlight innovative approaches that bridge mantle, lithospheric, crustal, and surface processes.
We welcome contributions that explore the coupling of tectonics and surface processes, including the roles of climate, erosion, sedimentation, and deep Earth dynamics in shaping the Earth's surface over time.
Orals: Thu, 7 May, 08:30–10:15 | Room D3
Exhumation strongly influences the structural, pressure and temperature evolution of sedimentary basins, and thus the formation and distribution of mineral and energy resources. It is commonly quantified using compaction-based methods that rely on sonic, porosity and thermal data to reconstruct uplift from maximum burial depths, typically via empirical relationships. However, these relationships are often calibrated for specific geological settings and then transferred elsewhere, and even region-specific models use parameters that vary within measurable ranges but are usually treated as exact. Data errors and unquantified parameter uncertainties can therefore propagate through the calculations, significantly compromising the reliability of exhumation estimates.
We previously developed a probabilistic compaction model for the Northern Carnarvon Basin (NCB) in the Australian North West Shelf (NWS) using sonic data from normally compacted, unexhumed intervals. Research shows that the dynamic evolution of the NWS basins has been shaped by multiple rifting and extensional phases and magmatic activities associated with Gondwana dispersal, and by later regional tilting linked to subduction along the northern margin. These complex histories imply significant basin-scale variability in subsidence and exhumation patterns, suggesting that NCB compaction behaviour may differ substantially from that in neighbouring basins such as Browse, Roebuck and Bonaparte. Here we extend probabilistic compaction analysis across these basins, deriving basin-specific shale compaction trends and comparing them to identify key similarities, differences and their geological controls. In doing so, we explicitly test whether a single “regional” compaction model is sufficient for exhumation analysis on the NWS, or whether basin-scale models are required.
Model robustness is evaluated using Markov chain Monte Carlo (MCMC) sampling, and uncertainty propagation is used to quantify the effect of parameter uncertainty on exhumation estimates. The NCB model shows strong similarity to Roebuck Basin trends but diverges from those of the Vulcan Sub-basin in the Bonaparte Basin. We attribute these differences to contrasting tectono-thermal histories, particularly the stronger influence of proximal subduction on the Bonaparte Basin. Our results indicate that while the NCB model may be cautiously transferable to the nearby Roebuck and parts of the Browse Basin, applying it to the distal Bonaparte Basin introduces substantial uncertainty. We demonstrate that, wherever data permit, basin-specific probabilistic compaction models are preferable to regional or global models for reliable exhumation analysis on complex passive margins such as the NWS.
How to cite: Makuluni, P., Hauser, J., and Clark, S.: Basin-specific versus regional compaction models: quantifying uncertainty in exhumation estimates on the Australian North West Shelf, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16214, https://doi.org/10.5194/egusphere-egu26-16214, 2026.
Rate and timing of neotectonic vertical motions represent an ongoing research topic in inverted sedimentary basins. This presentation offers new data concerning the uplift history of the western part of the Miocene Pannonian Basin system, (Central Europe) which is bordering the Alpine orogenic belt. After the syn-rift phase of ~21–15Ma, the area underwent the post-rift phase which involved differential subsidence reaching several kilometres in basin centres. Parallel to post-rift subsidence process, the basin inversion started during the Late Miocene and resulted in differential uplift, fluvial and aeolian denudation, and river incision.
The late post-rift and the early neotectonic phases were accompanied by extensive basalt volcanism, resulting in the activity of two distinct phreatomagmatic monogenetic volcanic fields, the Bakony-Balaton Highland and Little Hungarian Plain Volcanic Fields (BBHVF and LHPVF) through the Late Miocene to earliest Quaternary (7.96–2.61 Ma). The volcanic fields comprise diverse volcanic landforms, including shield volcanoes, maar diatremes, volcanic plugs and erosional remnants of scoria and spatter cones.
Detailed analysis of volcanic facies was used to reconstruct the topographic position of the syn-volcanic palaeosurface upon which the volcanoes developed. Using the previously published ages of the volcanic rocks and the palaeo-elevations of the volcanic surfaces, averaged uplift rates were derived for all observation points. In addition, previously published exposure age data and geomorphological data were used to constrain the uplift rates.
The reconstructed palaeosurfaces and the calculated rock uplift rates show spatial and temporal variations from ~20 to ~100 m/Ma. Before ~3.5 Ma the two volcanic fields showed opposite differential vertical motions having been positive in the eastern basin margin (Transdanubian Range) and negative in the neighbouring basin centre (Kisalföld/Danube Basin); variations were due to differential post-rift subsidence and the onset of minor neotectonic uplift. After ~3.5 Ma all the studied areas underwent uplift, but the south-western part of the volcanic fields exhibits larger uplift values than the north-eastern one triggering a regional drainage pattern reorganisation. Moving west from the volcanic areas, toward the foothills of the Alps, the uplift rates increased even more and approximating values obtained in the Alpine orogenic belt.
This variable differential vertical motion history points to the interplay of complex governing processes. These could involve the intraplate compressional stress related to neotectonic basin inversion, lower-crustal flow of the weakened crust, and more importantly, mantle processes at depth. This latter could involve lithospheric folding, mantle convection-induced development of a dynamic topography, and the eventual effect of secondary plumes. In addition, uplift could be coupled with surface processes like variable unloading by denudation and loading by sedimentation in the axial and marginal parts of the area, respectively.
The research was supported by the Hungarian National Research, Development and Innovation Office, project 134873 and the HUN-REN Research Grant Hungary project RGH531001.
How to cite: Fodor, L., Csillag, G., Németh, K., Ruszkiczay-Rüdiger, Z., Sebe, K., Telbisz, T., Kovács, G., and Cloetingh, S.: Neotectonic vertical motions based on syn-volcanic palaeosurfaces and geochronological data: inferences for crustal and mantle processes (Pannonian Basin, Central Europe), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17804, https://doi.org/10.5194/egusphere-egu26-17804, 2026.
The western Baiyun area in the northern South China Sea, particularly within the central Pearl River Mouth Basin (Zhu‐II Depression), hosts a complex detachment system. This study elucidates the tectonic control of a detachment-convergent transfer zone on the spatiotemporal evolution of the sedimentary basin system during the Eocene rifting. Integration of borehole and high-resolution 3D seismic data reveals that magmatic activity and reactivated pre-existing faults governed initial basin subsidence and the early development of high-angle normal faults in the upper crust. A fundamental shift occurred around ∼43 Ma (late Wenchang stage), when deformation transitioned to lower-crustal ductile thinning. This drove the formation of ductile‐crust domes, the rotation of faults into low-angle detachments, and ultimately, the establishment of the detachment-convergent transfer zone. This structural reorganization directly controlled basin geometry, transforming it from isolated, narrow, and deep lacustrine depocenters into a unified, wide, and shallow basin. Consequently, the sedimentary system evolved from fan delta‐braided river delta assemblages to braided river
delta‐beach bar systems. Constraining this tectonically dictated basin-fill architecture provides critical insights for predicting potential reservoirs in deep-water continental margins.
How to cite: Jia, Y., Xu, S., and Liu, Q.: Tectonic Control on Basin-Fill Architecture in a Detachment-Convergent Transfer Zone: The Pearl River Mouth Basin Example, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4660, https://doi.org/10.5194/egusphere-egu26-4660, 2026.
It is widely documented in the fluvial terrace and the sedimentary archive that Late Cenozoic landscapes have experienced an increase in non-steady-state uplift. With stepwise increase in uplift with climate transitions, this naturally led research to link uplift and climate. Further documented was the influence of crustal domain in controlling rates, where younger crust appears to react with greater intensity than its older, Archaean and Proterozoic counterparts. We began this project questioning that if Late Cenozoic crustal deformation is related in some way to increasing climate deterioration, then we should expect similar patterns during analogous periods. The selected period was the Late Palaeozoic Ice Age. Both exhibit similar low modelled CO2, high δ18O, high-frequency and high-magnitude oscillations in sea level, direct evidence of glaciation and, in comparison to earlier glacial episodes, biological complexity. Thermochronology data was compiled from terranes across Gondwana to provide a regional perspective of the nature of exhumation. The results are as follows. A pattern was evident of higher exhumation rates from Gondwanan-aged crustal domains in contrast to earlier Proterozoic and Archaean domains. Although expected and fitting with theory of how the crust deforms, this pattern is most curious. Linking the timing of exhumation with stages of climate deterioration proved difficult due to the resolution at which thermochronology describes exhumation. The presentation will explore the validity of assumptions and limitations of methodology and preservation of evidence, with discussion of avenues for further research on the topic.
How to cite: Galanis, Y. and Bridgland, D.: Crustal deformation of Gondwana during the Late Palaeozoic Ice Age, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17421, https://doi.org/10.5194/egusphere-egu26-17421, 2026.
The Panalesis model consists of global maps created every 10 million years or so from the Neoproterozoic to the present. These maps rely on a maximum of data from multiple sources (paleomagnetism, fossils, lithofacies, geochemistry, etc.) and comply with the rules of plate tectonics, following our Dual Control Approach methodology.
Once the global plate tectonics model has been defined, it is possible to derive many other types of maps. The first type of maps to be derived are palæogeographic maps. We supplement them however by maps of the age of the sea-floor, maps of accretion / subduction rates, maps of volume of subducted lithosphere, maps of hydrothermal alteration at mid-oceanic ridges, maps of crustal and lithospheric thickness, etc., which constitute the Panalesis Atlas. Associated with climate models, we show here an example of maps depicting the evolution of the drainage system at global scale through time and estimates of sediment fluxes over the Phanerozoic.
How to cite: Vérard, C. and Franziskakis, F.: The Panalesis model and its derivative maps: Implications for global long-term interaction between geodynamics and surface processes , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7294, https://doi.org/10.5194/egusphere-egu26-7294, 2026.
Back-arc extension is commonly assumed to be a steady, long-term process. However, geological records from the Japan Sea reveal a short-lived phase of rapid opening during the early–middle Miocene, followed by abrupt cessation. The geodynamic origin of this transient behaviour remains debated. This study employs three-dimensional geodynamic numerical models to investigate how oblique subduction geometry influences slab dynamics, mantle flow, and back-arc extension.
Our results show that a sufficiently high trench obliquity promotes slab breakoff at shallow upper mantle depths, forming a slab window and triggering a short-lived episode of strong lateral (toroidal) mantle flow. This flow dramatically accelerates back-arc extension and generates pronounced along-strike variations in spreading rates. As the slab window sinks into the mantle transition zone, the associated lateral mantle flow rapidly weakens, leading to a sharp decrease and eventual termination of back-arc spreading.
In contrast, models with lower subduction obliquity exhibit no slab breakoff, lack significant lateral mantle flow, and fail to reproduce rapid back-arc extension. These results suggest that slab breakoff induced by oblique subduction provides an efficient yet transient mechanism for focusing back-arc extension. Our findings offer a unified geodynamic explanation for the timing, spatial pattern, and abrupt end of Japan Sea opening. The proposed mechanism may also help explain slab window formation and episodic back-arc activity in other obliquely convergent margins.
How to cite: Luo, P. and Li, Z.-H.: Transient Acceleration and Termination of Japan Sea Opening Controlled by Oblique-Subduction-Induced Slab Window, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6108, https://doi.org/10.5194/egusphere-egu26-6108, 2026.
The interplay between tectonic shortening and surface erosion critically influences mountain building, yet their combined effects on vertical orogenic growth remain unclear. Here we present a suite of tectonic-geomorphology analogue experiments that combine brittle deformation with controlled rainfall-driven erosion. Under a certain shortening rate, we find that wedge height does not monotonically decrease with increasing erosion. Instead, the maximum orogenic wedge height occurs at a moderate rainfall/erosion rate, rather than under no or low erosion. To quantify this relationship, we introduce a dimensionless parameter, the rainfall-to-shortening ratio (R2S), and show that wedge height peaks at R2S ≈ 1. Compilation of data from 28 natural orogenic belts shows a similar bell-shaped trend, with maximum average elevations occurring at R2S ≈ 100, supporting the experimental results. The R2S difference between modeled and natural results likely represents the scaling difference of rainfall rate relative to shortening rate. We suggest that moderate erosion promotes vertical growth by reducing internal wedge strength and allowing the development of steeper critical surface slopes. These findings underscore the dynamic coupling between tectonics and surface processes and offer a scalable, physically grounded framework for understanding and predicting variations in mountain height across both experimental and natural systems.
How to cite: Wu, L. and Yang, B.: Moderate Erosion relative to Shortening Maximizes Mountain Heights in Active Orogenic Belts: Insight from tectonic-geomorphology analogue modelling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21847, https://doi.org/10.5194/egusphere-egu26-21847, 2026.
With the systematics migration of the Mendocino Triple Junction (MTJ), the San Andreas plate boundary forms within lithosphere transitioning from a convergent (subduction) to translation tectonic regime. How that transition occurs, and what crustal/lithospheric deformation is associated with the fundamental plate boundary change has not been well understood. Through the combined analysis of a detailed 3-D lithospheric structure in the vicinity of the MTJ (from seismic tomography) in conjunction with geodetic data, seismicity, regional thermochronology, surficial geomorphic characteristics, and observed heat flow we are able to delineate two distinct deformational corridors defining the tectonics of plate boundary transition. A well recognized consequence of MTJ migration is the development of a slab window in its wake. Our seismic tomographic imagery helps us define the extent of that slab window - in particular ion western boundary. We are also able to image a fragment of former Farallon plate (which we term the Pioneer fragment), now accreted to the Pacific plate, that has migrated with the MTJ, that also has served as the western boundary of the slab window. Geodetic data indicates the primary lithospheric-scale plate boundary structure forms along that Pioneer - slab window transition. The result is two distinctive corridors with quite discordant tectonic histories that lie on either side of the nascent plate boundary.
The Pioneer Corridor, which bounds the San Andreas Plate boundary on the west has experienced a coupled burial/erosion sequence as the MTJ migrates. This involves rapid rates of burial (Eel River Basin) followed by a short lived, but extremely rapid unroofing (~ 10 mm/yr) followed by subsequent, but slow exhumation. This results in major changes in observed surface heat flow, a complex pattern of low-T thermochronolgy ages, and a relatively subdued landscape (except in the region of rapid exhumation).
The Mendocino Crustal Conveyor (MCC) Corridor overlies the slab window, bounding the San Andreas boundary on the east. It has a distinctly different tectonic history involving a sequence of crustal thickening (uplift) followed by crustal thinning, with a complex lower bounding thermal evolution . The result is a quite different thermal-chronologic history, a variation in heat flow consistent with the crustal evolution, and a much more rugged landscape reflecting the long-lived uplift/exhumation history driven by slab-window processes.
Although the development of the San Andreas in the wake of the MTJ is oftentimes thought to be a tectonically simple process. This analysis indicates a very discordant history recorded in the thermal and surficial data of the two corridors bounding the nascent plate boundary.
How to cite: Furlong, K. P., McKenzie, K. A., and Herman, M.: Deformational Corridors along the San Andreas Plate Boundary: Evidence from Lithospheric Depths to the Surface, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8291, https://doi.org/10.5194/egusphere-egu26-8291, 2026.
The Cascadia forearc is unique among global subduction zones because of the accretion of a large igneous province (Siletzia) and continuous clockwise rotation of the margin due to oblique subduction of the Juan de Fuca plate. We reconstruct the stratigraphic architecture and sediment accumulation history in the forearc by investigating multiple, along-strike forearc basins. Integrating potential-field models, 2D seismic reflections, and deep borehole data, our 3D mapping allows us to track basin depocenters through space and time, revealing a fundamental structural shift in the Miocene that significantly reshaped the forearc.
During the Paleogene, the Cascadia forearc was a broad, marine basin characterized by high sediment accumulation rates and unrestricted accommodation space. Our results show that during the Miocene in the central forearc (Portland-Tualatin Basin), what was once a single continuous basin was subdivided as transpressional stress structurally inverted older Paleogene normal faults. Similarly, in the Chehalis Basin to the north, clockwise rotation reoriented fault systems relative to the regional stress field, pushing the basin depocenter northward as deformation shifted from northwest-striking to west-striking faults. This structural transition occurred as the outer-arc high (Coast Range) emerged, causing depositional environments to shift from marine to terrestrial. It is also coincided with a steep drop in sediment accumulation rates: a 7-fold decrease in the Chehalis Basin (196 to 27 m/Myr) and a 10-fold decrease in the Portland-Tualatin basins (305 to 29 m/Myr) to the south.
We propose that along-strike variations in subduction geometry also impact basin evolution. In the southern and central forearc, a relatively steep subduction angle and clockwise rotation pushed the outer-arc high close to the magmatic arc, leaving minimal accommodation space. In contrast, shallower subduction to the north near the Seattle Basin maintained a wider separation, allowing high sediment accumulation rates to persist through the Neogene (211 m/Myr).
By integrating basin analysis with regional tectonics, we constrain along-strike variation in Cascadia forearc geometry through the Cenozoic. We find that sustained rotation and the influence of Siletzia basement, not just sedimentary accretion, have controlled the evolution of fault systems and Cascadia forearc deposition. Accordingly, this work provides a framework for understanding the evolution of forearc basins where long-term rotation and strain-partitioning dominate.
How to cite: Bershaw, J., Moe, R., and Scanlon, D.: Cascadia’s Mid-Life Crisis: Miocene Changes in the Forearc due to Rotation and Subduction Dynamics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17015, https://doi.org/10.5194/egusphere-egu26-17015, 2026.
Posters on site: Wed, 6 May, 10:45–12:30 | Hall X2
The evolution of orogens and sedimentary basins, together with associated vertical motions and thermal fields, is controlled by crustal and lithospheric thickness variations, linked to plate kinematics and rheological properties. All these factors are tightly coupled to surface processes such as erosion and sedimentation, and they are linked to climatic variations. However, understanding the distinct effects and complex interplay between tectonic and surface processes requires new, coupled approaches.
Here we present results from three-dimensional numerical models based on the thermo-mechanical code I3ELVIS, which uses finite differences and marker-in-cell methods and incorporates elasto-visco-plastic rheologies of compressible and thermally expanding/contracting rocks and parametrized partial melting, coupled to a newly developed erosion–sedimentation module. Mass is conserved between eroded and deposited material at each time step. Surface evolution is governed by advection, onshore hillslope diffusion, fluvial incision following a stream-power law, sediment diffusion from river mouths into the sea and pelagic sedimentation, and is described by
∂h/∂t + uH ∇H h = uV + ∇H(κ ∇H h) - K Qm Sn + D
where h is the elevation, t is time, u is the velocity, H and V denotes horizontal and vertical quantities or operators, respectively, κ is diffusivity, K, m and n are stream power parameters, Q is water discharge, S is the local slope and D is a pelagic sediment source term. A node-based drainage network is built by steepest-descent flow routing, with discharge accumulated from laterally variable rainfall. Sediment delivered at river mouths is transported into the marine domain by a two-stage diffusive process, using a low diffusivity in proximal shelf environments and a higher diffusivity offshore to represent more efficient gravity-driven and pelagic redistribution.
Using this fully coupled framework, we investigate the effects of climate variability and mantle potential temperature during rifting and subsequent tectonic inversion. The models allow us to analyze strain localization, fault longevity, degrees of partial melting, and the spatial and temporal distribution of syn-tectonic sedimentary successions.
How to cite: Balázs, A., May, D., and Gerya, T.: Tectonics - erosion - sedimentation interactions during structural inversion: insights from fully coupled 3D numerical models, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11962, https://doi.org/10.5194/egusphere-egu26-11962, 2026.
In many natural systems, normal faults induce sedimentation in basins by creating depositional space that is gradually filled by incoming sedimentary infill. In this study, we investigated the response of deltaic systems to normal faulting through a novel analogue modelling approach integrating fluvial and tectonic processes. The models were built in a flume where the engine-driven extension was coeval with a river system controlled by water discharge and sediment feed. The river feeds the tectonically controlled basin where the deltaic lobes form. In the models, we varied engine velocity (i.e., extension/subsidence rate), while keeping the sediment influx and water discharge constant. Faulting of the model sand layers, representing the uppermost crust, is implemented in the flume by a mobile basal sheet, which is pulled from underneath a fixed block at constant velocity. The basin side (i.e., hanging wall) of the main normal fault is filled with water, while a predefined channel guides sediment-rich water towards the basin during early river incision. The river system scaling was done by discharge for the channel dimensions and by sediment mobility number for the sediment transport rate, while the fault slip rates were scaled based on natural fault-controlled basins such as the Roer Valley Graben or the Gulf of Corinth. The difference between natural temporal and spatial scales at which surface and tectonic processes operate was bridged by calculating the ratio between the creation of the accommodation space due to normal fault slip and the average sedimentation rate in the basin. This ratio is calculated for the entire basin and for a single lobe, and is ultimately the key parameter controlling the delta evolution.
The modelling results showed that the active faulting led to progradation and retrogradation of the delta. When the subsidence rate exceeds the sedimentation rate, the delta retrogrades early, and the branching of the delta lobes occurs later. In the model with similar subsidence and sedimentation rates over a lobe, the delta mainly experiences aggradation with several moderate prograding and retrograding cycles. In this situation, there is a minor lateral migration of the delta lobes without branching and significant avulsion. With low subsidence rates, the number of progradation-retrogradation cycles is increasing, the delta progrades farther into the basin, and can cross the conjugate basin-bounding fault(s). Such progradation-retrogradation cycles are often accompanied by local hiatuses, river avulsion, delta lobe branching and lateral migration, which are controlled by an interplay of external forcing and internal delta dynamics.
These findings facilitate understanding of the relationship between tectonics and delta dynamics in natural systems. For instance, due to the slow subsidence and a high sediment supply, the Roer Valley Graben is being overfilled in the early stages, with deltaic formations reaching the other side of the basin before shifting to a late-stage basin-parallel progradation. Contrastingly, the fast subsiding Gulf of Corinth, accompanied by a low sediment supply, has multiple small individual coeval delta lobes, which, presently, do not reach far into the graben and are unable to fill the created accommodation space.
How to cite: Krstekanic, N., van der Woude, D. H., Willingshofer, E., Kleinhans, M., and Matenco, L.: How normal faults control delta deposition: Insights from analogue modelling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5339, https://doi.org/10.5194/egusphere-egu26-5339, 2026.
Taiwan is situated within an active arc–continent collision zone and represents one of the most rapidly exhuming orogens on Earth, characterized by complex structural architecture. In our previous work, we developed a comprehensive thermomechanical model that incorporates the depth-dependent transition from brittle to ductile deformation, lithology-controlled erosion, and observed geometries of the basal decollement and backstop. The model successfully reproduces the key structural features of the northern Taiwan orogen and is consistent with metamorphic temperature profiles, thermochronological constraints, spatial patterns of strain, and the observed rates of exhumation and cooling. The results further demonstrate the critical roles of ductile deformation and ramp structures in the formation of the Hsuehshan Range and the Western fold-and-thrust belt.
Structural styles, however, vary systematically from north to south across the Taiwan orogen. Notably, the Hsuehshan Range is absent in southern Taiwan, and total crustal shortening decreases significantly toward the southern tip of the island.
Here, we apply the same thermomechanical framework under varying boundary conditions to reconstruct the along-strike evolution of mountain building across Taiwan.
Our results indicate that the timing of orogenic onset is comparable along strike, whereas the rate of shortening decreases progressively from north to south. The basal decollement extends to approximately 20 km depth and exhibits variable ramp–flat geometries, leading to distinct structural styles along the orogen. The model successfully captures the development of the Pingtung Basin and the structural evolution of the Hengchun Peninsula, providing a unified framework for understanding the along-strike variability of Taiwan’s orogeny.
How to cite: Zheng, M. J., Lee, Y.-H., and Tan, E.: Thermomechanical models of Taiwan’s orogeny with along-strike variability, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18447, https://doi.org/10.5194/egusphere-egu26-18447, 2026.
The existence of weak and shallow intra-crustal (salt) layers, syn-tectonic sedimentation as well as extensional inheritance have been shown to play a major role on deformational style and structural geometry of mountain belts on Earth. The Pyrenean orogen provides a well-constrained natural example of an inversion orogen strongly influenced by salt-detached foreland-fold-thrust belts. This study investigates the influence of pre-contractional salt and of syn-contractional salt deposition, together with inherited extensional structures, on crustal-scale mountain-building and associated foreland fold and thrust belt formation. To this end we use high-resolution thermo-mechanical numerical simulations based on the finite-element code FANTOM 2D, and explore the influence of salt viscosity, crustal flexural rigidity, extensional inheritance, crustal strength, and syntectonic sedimentation. By systematically varying those parameters, we can assess the impact of syn-tectonic salt deposition on the localization of deformation, thrust system evolution (both thick- and thin-skinned), and overall orogenic geometry. Comparison with the Pyrenees and other similar orogenic settings emphasizes the importance of extensional inheritance, syn-tectonic sedimentation and salt-tectonics during mountain building. Our models provide new insights into the mechanical role of evaporites in fold-and-thrust belt development.
How to cite: Gibellini, A., Huismans, R. S., and Wolf, S. G.: Effect of rift inheritance and salt layers on mountain building – a numerical modelling study motivated by the southern Pyrenean foreland fold-and-thrust belt, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12231, https://doi.org/10.5194/egusphere-egu26-12231, 2026.
The structural style of foreland fold-and-thrust belts (FTBs) is highly sensitive to variations in pre-existing structures, three-dimensional décollement distribution, and syn-tectonic sedimentation. However, the relative importance of these factors and their influence on 2D and 3D structural variability remain poorly constrained. The pronounced along-strike variability of the Andean foreland FTB makes this region an ideal natural laboratory to investigate these interactions. We use the thermo-mechanically coupled tectonic model FANTOM 2D to produce high-resolution, fold-and-thrust belt–scale simulations that explore the interaction between internal properties of the wedge and surface processes. We systematically vary the strength of the two décollement horizons, combined with syn-tectonic sedimentation, and explore how this controls variability in structural styles of FTB formation. Our results show that a strong basal décollement combined with a weaker upper décollement leads to a steeper wedge taper and the development of an antiformal stack in the internal part of the fold-and-thrust belt and, in the foreland, all thrusts detach on the upper décollement, involving only the upper layer. In contrast, models with a weak basal and stronger upper décollement produce a lower-taper wedge, with thrust sheets detached solely on the basal décollement, propagating toward the foreland in a piggyback sequence. Structural complexity and kinematic variability increase when both décollements have similar low to intermediate strengths and interact with syn-tectonic sedimentation. Thrusts originate simultaneously in both décollements, involving the lower and upper layer in an alternating sequence, leading to a complex interaction between thrust propagation in the two layers. The onset of each structure—commonly pop-ups and triangular zones—and their subsequent diverse evolution can serve as diagnostic indicators of the relative strength between décollements. These modeled structures are comparable to the along-strike structural variability observed in the Bolivian fold-and-thrust belt. While syn-tectonic sedimentation primarily controls the number and length of thrusts, our results emphasize the first-order role of décollement rheology in shaping foreland fold-and-thrust belt architecture and its kinematic evolution.
How to cite: Saiz, F., S. Huismans, R., and G. Wolf, S.: 2D models exploring factors controlling N-S variation of external foreland fold and thrust belt of the Andes (Southern Bolivia -Northwest Argentina), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12043, https://doi.org/10.5194/egusphere-egu26-12043, 2026.
To overcome the long-standing limitations of source-to-sink (S2S) studies of the Permian in the Junggar Basin—namely an overemphasis on static characterization and a lack of constraints from numerical sedimentary modeling—this study aims to develop an integrated, basin–mountain coupled forward-modeling workflow for the S2S system of the Lower Permian Wuerhe Formation. The goal is to achieve a dynamic, quantitative reconstruction of source-area surface processes, sediment supply, and basin depositional responses, and to predict sandbody distribution. The research includes: (1) within a unified spatial framework, characterizing accommodation-space evolution controlled by source-area tectonic evolution, rainfall and erosion-driven sediment supply, as well as depositional-area subsidence and lake-level variations; (2) deriving key surface-process and paleogeomorphic parameters, including paleoflow directions, time-varying runoff and sediment fluxes, and background geomorphic attributes (paleoslope, paleo-elevation, and paleowater depth); and (3) simulating sediment transport and deposition within the lacustrine basin to establish spatiotemporal evolution of geologically interpretable products—lithology, water depth, facies belts, sandbody distribution, depositional thickness, and stratigraphic architecture and sequence-filling styles—and constraining these results with geological observations.
Methodologically, we first prescribe initial topography and uplift rates in the source area, the spatiotemporal distribution of rainfall intensity, erosion rates of the source rocks, and a lake-level curve, while assigning a basement subsidence rate in the depositional area to jointly constrain the temporal evolution of accommodation space. We then run Badlands to obtain key outputs from topographic evolution and drainage/flow-routing calculations, and use these outputs as boundary conditions for Sedsim to perform depositional forward modeling and generate sedimentary results directly comparable to geological interpretation. Finally, the forward-model outputs are calibrated against well, seismic, and outcrop data; sensitivity analyses and iterative updates are conducted for critical parameters (uplift, erosion, rainfall, lake level, and subsidence) to obtain an optimal parameter set that is both process-consistent and consistent with observations.
The results indicate that the coupled Badlands–Sedsim forward-modeling workflow effectively transfers quantitative signals of source-area surface processes into basin-scale depositional responses, enabling a shift in S2S studies from “static description” to “process-based dynamic constraint.” Through data calibration and sensitivity-driven iteration, the workflow significantly improves the geological consistency and interpretability of the simulation results, providing a reproducible quantitative approach for understanding sedimentary evolution, sequence-filling mechanisms, and predicting favorable sandbody fairways in the Permian Junggar Basin, particularly for the Lower Permian Wuerhe Formation.
How to cite: Chen, X. and Wang, J.: Simulation of the Permian Source-to-Sink System in the Junggar Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3093, https://doi.org/10.5194/egusphere-egu26-3093, 2026.
The paleoenvironmental and provenance evolution of the Campanian Gosau Group sediments at Grünbach-Neue Welt in the Eastern Alps of Austria was investigated across a continuous transition from terrestrial to marine settings during the depositional period, coinciding with the boundary between the Lower and Upper Gosau subgroups. This transition was primarily driven by tectonic subsidence triggered by the northward subduction of the Penninic Ocean along the northern margin of the Austroalpine microplate. The sedimentary successions record depositional and environmental changes associated with subsidence. Integrated lithological, petrographic, paleontological, mineralogical, and geochemical analyses were performed to reconstruct the paleoenvironmental conditions and trace the sedimentary provenance. Paleoenvironmental analysis implied that the Grünbach Formation (upper Santonian to lower Campanian) represents a terrestrial-dominated setting with episodic marine incursions while the overlying lower Piesting Formation (upper Campanian) is dominantly shallow-marine setting with terrestrial input. The shift toward less weathered, coarser detritus sediments across the two formations suggests changes in sediment transport pathways and sources, likely influenced by subsidence, marine transgression, and source areas’ uplift. This study provides valuable insights into the Campanian paleoenvironment and provenance shifts of the Gosau Group, highlighting the complex interplay between subsidence, sea-level fluctuations, and sediment supply. Furthermore, it advances our understanding of how coupled environmental and tectonic processes influenced basin evolution.
How to cite: Xiang, X., Lee, E. Y., and Wagreich, M.: Paleoenvironmental Evolution and Provenance Shifts in Campanian Marginal Gosau Basins: Evidence from Sedimentary and Geochemical Records, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3851, https://doi.org/10.5194/egusphere-egu26-3851, 2026.
Unlike the wedge-shaped geometry typical of foreland basins, the interior of the Tibetan Plateau contains a series of large, closed basins. These basins are defined by thick sedimentary fills, a dish-shaped structural geometry, and a distinctly flattened to downward-convex morphology of the sub-basin Moho interface. However, the mechanisms governing their evolution remain debated. To address this, we employed numerical models that couple surface processes with lithospheric rheology to simulate the Cenozoic evolution of the Qaidam Basin, the largest sedimentary basin within the Tibetan Plateau, which has continuously accommodated substantial sediments derived from the surrounding mountain ranges throughout the Cenozoic. By systematically varying parameters from high to low erosion rates and from normal to strong mantle rheology, we compared model outcomes and successfully reproduced the observed geometry, topography, sedimentary sequence, and sub-basin Moho morphology of the Qaidam Basin. Our models reveal that dish-shaped basin evolution is controlled by three key factors: substantial sediment loading, a low crustal convergence rate, and a persistent centripetal sediment routing system. The sediment loading suppresses crustal deformation within the basin and drives downward deflection of the sub-basin Moho. Concurrently, a stronger mantle lithosphere localizes the deformation, resulting in a shorter-wavelength basin geometry. Our findings provide a new perspective for understanding deep intra-plateau basins by highlighting the governing role of coupled surface processes and lithospheric rheology. This mechanism not only explains basins within the Tibetan Plateau but also accounts for analogous settings, such as the Altiplano Basin in the Altiplano-Puna Plateau. Furthermore, the model is applicable to other dish-shaped basins formed under similar coupling conditions, exemplified by the Junggar Basin. Another key finding is that active surface processes can drive subsurface exhumation even under stable tectonic conditions. This suggests that accelerated cooling signals recorded by low-temperature thermochronology may not solely represent tectonic uplift acceleration, thereby implying that such data require careful reinterpretation.
How to cite: Xiong, H., Yang, H., and Wu, L.: Surface Forcing of Moho Topography in an Intra-Plateau Deep Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4164, https://doi.org/10.5194/egusphere-egu26-4164, 2026.
The microscopic pore systems in clastic reservoirs the margins of foreland basins are complex and heterogeneous, primarily controlled by the superimposition of burial diagenesis and tectonic diagenesis. These reservoirs have experienced not only vertical burial compaction but also intense lateral tectonic compression, accompanied by varying degrees of microfracture development and multiphase alteration by diverse diagenetic fluids. This study focuses on the Cretaceous Bashijiqike Formation in the Kushen area of the Kuqa Depression, Tarim Basin, which mainly consists of low-porosity and low-permeability to tight sandstone reservoirs deposited in a braided river delta environment. By systematically comparing burial depth, maximum paleo-stress, diagenesis, and microscopic pore characteristics across different tectonic positions, the study reveals how different reservoir-controlling factors combine to create different reservoir characteristics.
North to the Kelasu Fault, the reservoirs experienced relatively shallow burial (<4000 m) under strong tectonic stress. Diagenetic processes include compaction, calcite cementation, and meteoric water dissolution. Reservoir pores are dominated by primary pores with minor dissolution pores, accompanied by abundant microfractures. Between the Kelasu and Keshen Faults, reservoirs underwent deeper burial (6500-7000 m) under moderate tectonic stress. Diagenesis includes compaction, multi-type cementation (dolomite > quartz > albite > calcite > anhydrite), and multi-phase dissolution. Reservoir pores consist of mixed primary and dissolution pores, with dissolution pores exceeding primary pores in abundance, and local microfracture development. Between the Keshen and Baicheng Faults, reservoirs are characterized by ultra-deep burial (~7500 m) and low tectonic stress. Diagenesis includes compaction, multi-type cementation (dolomite > calcite > anhydrite > albite > quartz), and multi-phase dissolution. Reservoir pores are mainly primary pores with subordinate dissolution pores, and microfractures are rarely developed.
From north (foreland basin margin) to south (basin interior), increasing burial depth enhances vertical compaction, while decreasing tectonic stress reduces tectonic compaction and microfracture development. Concurrently, diagenetic fluids evolve from dominantly meteoric water in the north to multi-phase complex fluids including meteoric water, lagoon water, and organic acids in the south. These factors collectively control the diagenetic evolution and heterogeneity of microscopic reservoir pores in the study area.
Keywords: Tectonic stress; Diagenesis; Microscopic pore; Bashijiqike Formation; Kuqa Depression
How to cite: Zheng, X. and Sun, X.: Microscopic reservoir pores heterogeneity and its controlling factors of the Bashijiqike Formation in the Kuqa Depression, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4210, https://doi.org/10.5194/egusphere-egu26-4210, 2026.
How to cite: Gao, P.: Thermal History Reconstruction of the Yaziluo Aulacogen, Paleo-Tethyan Complex Tectonic Domain: Coupled Constraints from Multitype Thermal Indicators, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20539, https://doi.org/10.5194/egusphere-egu26-20539, 2026.
This study of the subsurface conditions within a fluvial system impacted by the Red Sea rift tectonics offers an integration of geological and geophysical observations from Al-Shout Valley in western Saudi Arabia. Two primary fracture orientations are revealed by structural measurements, suggesting regional tectonic control. While Vertical Electrical Sounding (VES) data define the transition from unconsolidated sediments to gravel layers and underlying bedrock, high-resolution Ground Penetrating Radar (GPR) profiles show varying sediment thickness and shallow subsurface heterogeneity. The significant sediment variability and a strong tectonic influence on the valley evolution are shown by the combined dataset. These findings will advance our knowledge of near-surface architecture and fluvial stratigraphy in environments associated with arid rifts.
How to cite: AlHumidan, S. and Alhejji, S.: Integrated Geological and Geophysical Investigation of Al-Shout Valley, Saudi Arabia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17815, https://doi.org/10.5194/egusphere-egu26-17815, 2026.
Topography and erosion in active convergent mountain belts arise from coupled feedbacks between
tectonics, climate, and surface processes. Tectonic deformation generates topography through crustal
shortening and thickening, which modifies precipitation via orographic effects. Enhanced precipitation
drives river incision, mass wasting, and sediment transport that erode the landscape, feeding back into
topography and precipitation patterns over geological timescales.
In the Himalaya, crustal shortening produces an orogenic wedge above the Main Himalayan Thrust, the
basal décollement with a flat-ramp-flat geometry where sub-horizontal flats at different crustal levels are
connected by inclined mid-crustal ramps. Wedge growth occurs primarily through basal accretion, whereby
material from the subducting Indian plate is scraped off and emplaced beneath the wedge as thrust-bounded
rock slices (horses) between a floor thrust and roof thrust, forming a mid-crustal duplex. As convergence
continues, this process operates episodically: new horses are sequentially accreted through footwall
imbrication, punctuated by phases when breakthrough ramps form to transfer slip between décollement
levels. This temporal cyclicity in basal accretion creates alternating phases of duplex thickening and ramp
activation. However, how this cyclic process modulates climate-tectonic feedbacks—specifically, how
episodic duplex growth and ramp activation influence topographic evolution, precipitation distribution, and
erosion rates across the wedge—remains poorly constrained over tens of millions of years.
To investigate these feedbacks, we employ a 2D coupled lithosphere-scale numerical framework that
captures the physics of climate–tectonic–surface interactions, building on the coupled modelling approach
developed by Yuan et al. (2024). This framework integrates a thermomechanical geodynamic model
(ASPECT) to account for tectonic deformation and uplift, a landscape evolution model (FastScape) to
simulate surface processes and an orographic precipitation model (LFPM) to evaluate climate–topography
feedbacks. We reproduce first-order geometries of the India-Eurasia collision zone by introducing crustal
décollements as pre-defined horizontal weaknesses in the Indian pate.
Preliminary results indicate that variations in basal décollement strength modulate tectonic style and ramp
cyclicity, controlling mountain-belt width and, in turn, precipitation patterns and surface erosion across
different ramp phases. A stronger basal décollement relative to an intermediate décollement leads to the
development of distinct inner and outer wedges. The outer wedge thereby grows laterally by frontal
accretion while uplift of the inner wedge occurs via duplex formation. Uplift of the inner wedge produces a
highly elevated, low-relief landscape, suggesting a transient geomorphic response to ongoing duplex uplift,
as observed in parts of the Himalaya. In these zones, two distinct rainfall maxima are observed, associated
with the inner and outer wedges, along with corresponding dual bands of high relief and enhanced channel
steepness. We find that variations in erosional parameters, together with crustal rheology, can substantially
influence the geometry of the Himalayan wedge, thereby modulating crustal deformation, topography
changes and the climate.
Reference: Yuan, X., Li, Y., Brune, S. et al. Coordination between deformation, precipitation, and erosion
during orogenic growth. Nat Commun 15, 10362 (2024). https://doi.org/10.1038/s41467-024-54690-4
How to cite: Kundu, S., Brune, S., Scherler, D., Neuharth, D., Yuan, X., and Mandal, S. K.: Tectonic and Climatic Controls on Himalayan Topographic Evolution: Numerical modelling of tectonics-erosion-precipitation interactions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9873, https://doi.org/10.5194/egusphere-egu26-9873, 2026.
Salt rich margins are characterised by complex structural and thermal regimes due to the high thermal conductivity of evaporites (~6.5 Wm-1K-1) and their interaction with the insulating sedimentary cover (~2.0 Wm-1K-1). Observational evidence and well data demonstrate the existence of thermal anomalies in proximity to salt structures in salt-bearing basins. Furthermore, these rocks exhibit extremely low viscosity and an absence of shear strength, thus allowing for the occurrence of highly non-linear salt tectonics, otherwise referred to as halokinesis. While the structural mechanics of halokinesis are well-documented, the dynamic feedback between sedimentation rates, salt geometry, and the basin's thermal evolution remains under-explored in geodynamic models.
In this work, we investigate this interplay using a 2D thermo-mechanical numerical code (Mandyoc). A rifted margin was modelled under three post-salt sedimentation rates, with realistic salt thermal properties being compared against control scenarios where salt is thermally equivalent to the crust. Our models replicate the expected behaviour of the salt tectonics, with depocentre migration, diapirism, nappes and welds. The structures in the sediments are marked by extension in the proximal domain, and compression in the distal domain. The results obtained demonstrate that the thermal field is strongly affected by the sedimentation rate, since it is the primary cause of halokinesis.
In low sedimentation regimes, the effect of the salt high conductivity dominates. Diapirism and allochthonous nappes efficiently conduct heat to the surface, cooling the sub-salt section and depressing isotherms, potentially retarding source rock maturation. In the moderate sedimentation rate scenario, the salt movement creates more complex structures and the isotherms are modified depending on the structure thickness and range. In a high-sedimentation regime, the rapid progradation suppresses vertical salt tectonics and creates a thick, low-conductivity clastic wedge. In this instance, the sedimentary blanketing effect is more significant than the salt cooling effect, which results in heat trapping and accelerated thermal maturation in the pre-salt layers.
Our findings point that the salt layer acts not only as a structural seal or a detachment layer but as a dynamic thermal modulator. The effectiveness of the salt as a "radiator" is strictly controlled by the competition between the halokinesis and progradation rate. Disregarding this coupling in basin modelling may lead to significant misinterpretations of the oil maturation window and the thermomechanical evolution of the distal margin.
This work has been by Petrobras Project 2022/00157-6 and has been financially supported by the Human Resources Program of the Brazilian National Agency for Petroleum, Natural Gas, and Biofuels – PRH/ANP43 (2025/21407-9). We also would like to express our fully gratitude to Leonardo M. Pichel and the Bergen Research Group because of its extensive collaboration with us.
How to cite: Bueno, J., Almeida, R. P., and Sacek, V.: How post-salt sedimentation rates control the thermal evolution of salt-bearing margins: The interplay between thermal blanketing and salt effects, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2795, https://doi.org/10.5194/egusphere-egu26-2795, 2026.
Based on the latest drilling, logging, and seismic data, and using key tectonic interfaces as markers, this study divides tectonic strata in combination with regional tectonic movements, establishes a vertical stratigraphic framework, and reconstructs erosion amounts. It clarifies the present-day preservation, post-depositional erosion, original distribution characteristics, and their spatiotemporal variations for each stratum, systematically revealing how their development features respond to the basin's tectonic evolution. The results indicate that the Mesozoic tectonic layer in the Jiyang Depression can be subdivided into three sublayers: Early-Middle Triassic, Early-Middle Jurassic, and Early Cretaceous. The Cenozoic tectonic layer can be subdivided into five sublayers: Kongdian–Lower Es4, Upper Es4–Lower Es2, Upper Es2–Dongying, Guantao–Minghuazhen, and Pingyuan Formations. The distribution of preserved strata from bottom to top is uneven, with significant variations among different tectonic units and layers, reflecting the combined effects of original deposition and subsequent erosion. The Early-Middle Triassic period inherited the tectonic framework and sedimentary characteristics since the Late Hercynian, forming a large-scale inland depositional system. The Early-Middle Jurassic represented a transitional period from the Paleo-Asian tectonic domain to the circum-Pacific tectonic domain, characterized by early-stage filling and late-stage draping. The Early Cretaceous exhibited reverse fault depression, trending northwest, with greater depositional thickness near the Zhangjiakou–Penglai fault zone. The Cenozoic was marked by mantle upwelling and lithospheric thinning, with the Paleogene characterized by multi-episodic extensional fault depression and the Neogene–Quaternary by regional sag depression. The Jiyang Depression underwent multiple phases of complex tectonic evolution during the Mesozoic and Cenozoic, leading to widespread erosion at the tops of the Late Triassic, Late Jurassic, Late Cretaceous, Lower Es4, and other tectonic sublayers.
How to cite: Jia-xin, L.: Development Characteristics of Mesozoic-Cenozoic Tectonic Strata in the Jiyang Depression and Their Response to Tectonic Evolution, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13391, https://doi.org/10.5194/egusphere-egu26-13391, 2026.
The Southern Apennines collisional belt is connected to the Calabrian Arc subduction system across the Gulf of Taranto area (Southern Italy). The role of active deformation during the late Pleistocene-Holocene time is a matter of debate. Our research focused on the feeding area of the Taranto Canyon, the main morphological feature of the continental slope in the study area. The headwall canyon incises the continental margin from the shelf break, at about 30 m b.s.l., down to 450 m depth, covering an area of about 50 km². A novel, high-resolution multibeam bathymetry was acquired using a Multibeam Echo-Sounder system. A total of approximately 1600 km² of high-resolution bathymetric data were collected, with a final gridded resolution of 10 × 10 m, referenced to Mean Sea Level. Bathymetry was used to generate a Digital Elevation Model (DEM), allowing reliable morpho-structural and hydrographic analysis. In addition, a total of 650 km of seismic lines were collected across the outer continental shelf and slope in the north-eastern sector of the Gulf of Taranto, using the GeoResources Geo Spark 200 Sparker system, operating at 1 kJ. The adopted configuration allowed a dominant frequency range between 500 and 2000 Hz, a pulse length of ~0.5 ms, allowing imaging depths between 200 and 400 ms, two-way travel time. These acquisition parameters ensured a high-resolution imaging of buried sedimentary units, stratigraphy and tectonics. The interpretation of seismic sparker profiles, along with the high-resolution bathymetry, reveal deformations and small-scale thickness variations within Pleistocene–Holocene units. The integration of morphostructural and geophysical data suggests that present-day deformation exerts a primary control on canyon evolution and slope dynamics of the north-eastern Gulf of Taranto. These results provide new insights into the recent geodynamic evolution of the Southern Apennine front and highlight its implications for potential geohazard assessment.
How to cite: Massa, B., Meo, A., Ciarcia, S., and Senatore, M. R.: The Southern Apennine front: evidences of recent activity at the Gulf of Taranto (Italy)., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14294, https://doi.org/10.5194/egusphere-egu26-14294, 2026.
Understanding the origin of high-frequency stratigraphic heterogeneity in active orogenic basins is essential for distinguishing the relative contributions of regional tectonics and local environmental forcings. In the offshore areas of central Taiwan, the Early Pleistocene to present Toukoshan Formation exhibits complex architectural variations that challenge singular tectonic interpretations. This study utilizes multichannel seismic reflection profiles and borehole data to dissect the evolutionary mechanisms driving these stratigraphic shifts. While the underlying Late Miocene to Early Pleistocene sequences exhibit architectural stability as well-stratified reflections, the Toukoshan Formation marks a transition to highly discontinuous geometries, reflecting a switch in dominant drivers toward localized hydrodynamic forcing. The lower Toukoshan Formation features co-existing parallel and progradational clinoform geometries, indicating significant lateral variations. These progradational structures are vertically overlain by continuous, sub-parallel reflections, recording a low-to-high-to-low energy transition. While tectonic subsidence typically produces laterally continuous stratigraphic geometries, the observed progradational sets in this study exhibit marked vertical and lateral discontinuities. This suggests that localized stratigraphic architecture is decoupled from the gradual tectonic trend, reflecting a switch in dominant drivers toward rapid hydrodynamic forcing. Such features likely record wave-driven sediment redistribution and the development of localized barrier complexes under high-energy conditions during relative sea-level fluctuations, rather than being a direct response to tectonic loading. Correlation of key time horizons across multiple seismic profiles reveals a southward migration of the depocenter within the Toukoshan Formation. This spatial pattern is consistent with the southward propagation of the orogenic belt and the resulting higher subsidence rates in the south as noted in previous studies, indicating that such regional-scale sediment redistribution is primarily governed by foreland basin subsidence. Our findings reveal a decoupling of stratigraphic drivers: while isopach maps confirm sustained tectonic control over regional accommodation, the internal architecture of the Toukoshan Formation marks a switch to localized hydrodynamic forcing. Wave-driven sediment supply and reworking overrides the tectonic signal, creating high-frequency heterogeneity and proving that even under active tectonics, environmental energy can be the primary sculptor of the depositional landscape.
How to cite: Tsai, M.-Y., Hsu, H.-H., Chen, T.-T., Liu, C.-S., Lin, L.-F., and Mirza, A.: Contrasting Tectonic and Hydrodynamic Controls on the Infill of the Toukoshan Formation: A Seismic Stratigraphic Study Offshore Central Taiwan, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17238, https://doi.org/10.5194/egusphere-egu26-17238, 2026.
The sedimentary fill of foreland wedge-top basins is characterized by an intricated depositional architecture, resulting from superposition of tectonics and sedimentation. This study explores the relationship between tectonics and basin evolution through the analysis of the Eocene-Miocene depositional systems formed in the Alps-Apennines junction wedge-top basin (northwest Italy). We implemented a 3D geologic model, providing thickness and lateral facies variations, as well as the architecture of these systems. To this aim, we analysed subsurface and surface data, including seismic reflection profiles, field observations, and facies analysis of the outcropping successions. Five major units were identified within the basin, which are representative of key stages in its tectonic evolution. An initial phase of basin subsidence (Eocene-Oligocene) culminated in the establishment of a widespread deep-water environment, characterized by high efficiency turbidite systems (Burdigalian). Afterwards, the progression of Apennine deformation led first to basin tilting and then basin inversion and progressive shallowing (Middle to Late Miocene). The 3D model is the basis for a quantitative characterization of the relationship between tectonic subsidence and sediment accumulation, useful to understand the complex evolution of this and analogue sedimentary basins.
How to cite: Vidal Reyes, M. I., Marini, M., Amadori, C., Reguzzi, S., Maino, M., Menegoni, N., Nader, F. H., and Tesauro, M.: Eocene – Miocene geologic evolution of the Alps-Apennines junction wedge top basin in northwest Italy, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20363, https://doi.org/10.5194/egusphere-egu26-20363, 2026.
Posters virtual: Wed, 6 May, 14:00–18:00 | vPoster spot 1a
EGU26-3508 | Posters virtual | VPS30
Subsurface structural mapping using high-resolution gravity data and advanced processing techniques in the Ouarzazate Basin, Southern Morocco.Wed, 06 May, 14:12–14:15 (CEST) vPoster spot 1a
This study investigates the deep structure of the Ouarzazate Basin, located between the Central High Atlas and the Anti-Atlas, using gravity data analysis. Gravimetric methods were applied to map subsurface structural lineaments beneath the sedimentary cover. The resulting structural map reveals that the basin is mainly controlled by ENE-WSW oriented faults, with subordinate E-W and NE-SW trends related to Variscan deformation, Triassic-Jurassic rifting, and Atlas tectonic inversion. Positive gravity anomalies show preferential NE-SW and E-W orientations and are linked to the structural configuration of the Central High Atlas, which acted as a major source area for the basin. The identified fault systems and compressional structures in the Central High Atlas and Anti-Atlas are consistent with the regional geodynamic evolution. These results highlight the strong tectonic connection between the Ouarzazate Basin and adjacent Atlas basins, particularly the Central High Atlas, and provide new insights into the basin’s geodynamic development.
How to cite: Bouali, B., Tabayaoui, F.-Z., Sahbi, H., Manar, A., Nouayti, A., Boujamaoui, M., and Berkat, N. E.: Subsurface structural mapping using high-resolution gravity data and advanced processing techniques in the Ouarzazate Basin, Southern Morocco., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3508, https://doi.org/10.5194/egusphere-egu26-3508, 2026.
