Many cratonic continental fragments dispersed during the rifting and break-up of Gondwana are bound by steep topographic landforms known as ‘great escarpments’, which rim elevated plateaus in the craton interior. In terms of formation, escarpments and plateaus are traditionally considered distinct owing to their spatial separation, occasionally spanning more than a thousand kilometres. We integrate geological observations, statistical analysis, geodynamic simulations, and landscape-evolution models to develop a physical model that mechanistically links both phenomena to continental rifting (Gernon et al., 2023, 2024). Escarpments primarily initiate at rift-border faults and slowly retreat at about 1 km Myr−1 through headward erosion. Simultaneously, rifting generates convective instabilities in the mantle—a ‘mantle wave’—that migrates cratonward at a faster rate of about 15–20 km Myr−1 along the lithospheric root, progressively removing cratonic keels, driving isostatic uplift of craton interiors and forming a stable, elevated plateau. This process forces a synchronized wave of denudation, documented in thermochronology studies, which persists for tens of millions of years and migrates across the craton at a comparable or slower pace. We interpret the observed sequence of rifting, escarpment formation and exhumation of craton interiors as an evolving record of geodynamic mantle processes tied to continental break-up, upending the prevailing notion of cratons as geologically stable terrains.
References
Gernon, T.M., Jones, S.M., Brune, S., Hincks, T.K., Palmer, M.R., Schumacher, J.C., Primiceri, R.M., Field, M., Griffin, W.L., O’Reilly, S.Y., Keir, D., Spencer, C.J., Merdith, A. & Glerum, A. Rift-induced disruption of cratonic keels drives kimberlite volcanism. Nature 620, 344–350, doi: 10.1038/s41586-023-06193-3 (2023).
Gernon, T.M., Hincks, T.K., Brune, S., Braun, J., Jones, S.M., Keir, D., Cunningham, A., & Glerum, A., Coevolution of craton margins and interiors during continental breakup. Nature 632, 327–335, doi: 10.1038/s41586-024-07717-1 (2024).
How to cite: Gernon, T., Hincks, T., Brune, S., Braun, J., Jones, S., Keir, D., Cunningham, A., and Glerum, A.: Mantle waves and the organised destabilisation of craton surfaces, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7110, https://doi.org/10.5194/egusphere-egu25-7110, 2025.
Basin-filling strata form casts of the surface topography, preserving records of tectonic events that are the foundation of our understanding of orogen dynamics today. Prevailing models for basin formation have proven useful for the interpretation of the vast majority of the sedimentary record, from continental scale deposystems like foreland basins to fault-bound deposystems along rifts and thrusts. However, the persistence of high-elevation, hinterland depocenters for millions of years, often without obvious causes of tectonic subsidence, presents a sedimentological conundrum. Non-tectonic topographic depressions on high plateaus, such as those created by aeolian excavation or volcanic damming, are finite in volume and likely to be quickly filled over geologic time. The maintenance of depression therefore generally requires the generation of new accommodation. When these enigmatic, long-lived lacustrine depocenters on high plateaus are also paired with adjacent, coeval mantle-derived magmatism, which is evidence of the disturbance of thermodynamic equilibrium at the base of the lithosphere, it bears consideration whether these basins are the surface symptoms of deeper mantle dynamics. If so, they would constitute a new class of tectonic basins: dynamic rebound basins due to lithospheric removal. Such basins should share some hallmark characteristics: anomalous patterns of intrabasinal deformation that are difficult to explain given the regional tectonic setting, convex-up subsidence curves representing the coeval acceleration of accommodation space across the entire basin, evidence of the rapid deepening of a hydrologically closed basin around the end of the depositional record, subsequent rapid rebound (basin inversion/exhumation), and mostly importantly, sedimentologic/stratigraphic patterns fundamentally inconsistent with classic models for other tectonic basins.
How to cite: He, J.: Towards a new class of tectonic basins: Dynamic rebound basins and lithospheric dripping, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2427, https://doi.org/10.5194/egusphere-egu25-2427, 2025.
Anatolia is a major thoroughfare for faunal migration and its paleogeography impacted faunal dispersals from, and to, Africa, Europe, and Asia. For example, the first appearance of hominoids in central Anatolia was 2-6 Myr after the formation of the "Gomphotherium Landbridge" according to fossil records, yet the arrival of hominoids at a far more distant location in China occurred only 1-2 Myr after the formation of the landbridge. Furthermore, in the early Miocene, the populations of small mammals in Europe and Anatolia differed greatly. Mineral barometry-based crustal thickness calculations and Airy isostatic considerations suggest paleoelevations of 3.5–4.1 km in early Miocene western Anatolia. This presents the possibility that the observed delays in faunal dispersion and differences in faunal populations were the result of topographic barriers in western Anatolia. Nevertheless, the hypothesis that high elevations posed migration barriers in western Anatolia lacks supporting paleoelevation data. To test the hypothesis, we first established a new geochronological model for the Gördes Basin based on U-Pb ages from sandstones and tuffs collected from new stratigraphic sections and then measured hydrogen isotopic ratios of 13 volcanic glass samples and oxygen isotopic ratios of 28 carbonate samples from that basin. The onset of the sedimentation of the Gördes Basin at 18-19 Ma based on both maximum depositional ages (sandstone) and true depositional ages (tuffs) is younger than previously estimated at 21-20 Ma. We calculated the paleowater isotopic compositions with standard isotopic fractionation during precipitation and a 15°C precipitation temperature for CO3. Volcanic glass samples have δDpaleowater(pw) values ranging from -113.7 to -67.5‰ and δ18Opw values ranging from -12.9 to -6.1‰. Hydration by primarily ambient waters rather than magmatic water is indicated by a slight negative trend between δD and weight percentage H2O. The analysis of the δ18O and δ13C of alluvial carbonate samples and microphotographs demonstrate that they are not diagenetic. Paleoelevation was calculated using alluvial carbonate materials and volcanic glass samples with wt% H2O> 2. A 16 Ma paleosol sample in a marginal marine environment was chosen as a low-elevation baseline for determining Miocene paleoelevations. Calculated paleoelevations of 19-16 Ma western Anatolia are 3.6 ± 0.7 and 4.3 ± 0.9 km (1σ), based on the most negative δ values of -12.9‰ and -113.7‰ for δ18Opw and δDpw, respectively. Paleoelevations calculated based on the most negative quartile are 3.2 ± 0.5 km and 3.9 ± 0.6 km (2σ) for δ18Opw and δDpw, respectively.We conclude that the early Miocene topography in western Anatolia was approximately 2-3 km higher than the current topography, based on independent oxygen and hydrogen isotopic compositions of carbonate and volcanic glass paleoelevation proxies. Moreover, independent estimations based on Airy isostacy agree with the calculated paleoelevations. These factors together support the model of extreme early Miocene paleoelevations in western Anatolia and the hypothesis that early Miocene faunal dispersal was hampered by high relief. If that is the case, extensional deformation throughout the Miocene-Pliocene could cause a decrease in paleoelevation and an establishment of faunal migration corridors in the western Anatolia.
How to cite: Guan, X., Saylor, J., Özyalçın, C., Bindeman, I., Sundell, K., and Mackaman-Lofland, C.: High-elevation western Anatolian topography delayed faunal migration during the early Miocene, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15876, https://doi.org/10.5194/egusphere-egu25-15876, 2025.
The effect of the eastward growth of the Tibetan Plateau on the morphotectonic evolution of South China is still a matter of debate. Here, we report new apatite fission track, apatite (U-Th-Sm)/He and zircon (U-Th)/He dates and analog model reconstruct the Mesozoic-Cenozoic tectonic evolution of the southeastern Sichuan fold-thrust belt (SS-FTB), on the eastern margin of the Tibetan Plateau. Combined interpretation of thermochronology data and results of analog modeling show that the SS-FTB experienced an early northwestward progressive deformation between 100 Ma and 80 Ma forming several large-scale anticlines. A later accelerated cooling initiated between ∼35 Ma and 20 Ma, identified across the belt, implies that a crustal shortening and exhumation since the late Eocene-early Oligocene may have been widespread along the Sichuan Basin. This latter exhumation was a response to the far-field effect of the eastward growth of the Tibetan Plateau, which is accounted for the counterclockwise rotation axes of pre-existing anticlines and formation of a younger anticlines, hence the curved geometry of the belt.
How to cite: Feng, Q., Qiu, N., Koyi, H., and Borjigin, T.: Late Eocene-Early Oligocene Eastward Growth of the Tibetan Plateau: Insights from Crustal Shortening of the Sichuan Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2562, https://doi.org/10.5194/egusphere-egu25-2562, 2025.
We conduct a new analysis of the geomorphology, calibrated to basin-averaged erosion rates, for the Three Rivers Region (TRR), the southeastern part of the Tibetan Plateau, drained by three major rivers that flow in parallel from north to south —the Salween, Mekong, and Yangtze. We combined DEM analysis of channel steepness indices of the trunk rivers and the tributaries with cosmogenic nuclide concentrations, measured in modern river sands collected from tributaries of these three major rivers. Our analysis reveals surprisingly low erosion rates for a high-relief mountain region, with an exception of the Meili Mountains, where significantly higher rates correlate with high river steepness. This localized anomaly appears to be related to high rock uplift rates associated with a compressive stepover structure linking the Parlung and Zhongdian strike-slip faults. In addition to this local process, we identify a broader west-to-east gradient of decreasing erosion rate and river steepness. This gradient cannot be explained by tectonic models favoring north-south movement but instead reflects the influence of the Indian Plate and Burma's indentation into South China. To further investigate these dynamics, we developed a kinematic model using GPS velocity data to reconstruct the relative positions of India, Burma, and the TRR over 20 Ma. The model estimates approximately 120 km of maximum TRR shortening, offering insights into the geomorphic evolution of this region.
How to cite: Fang, X., Willett, S. D., Yang, R., Scherler, D., Haghipour, N., and Christl, M.: Spatial patterns of erosion rates and topographic steepness in the Three Rivers Region, southeastern Tibet, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6549, https://doi.org/10.5194/egusphere-egu25-6549, 2025.
Many of the Earth's highest mountain peaks are located at the dissected fringe of large orogenic plateaus such as the Tibetan Plateau or the Altiplano. The striking spatial coexistence of exceptionally high peaks with rivers that incise the edge of the plateau led Wager to propose the co-evolution of valleys and mountain peaks more than a hundred years ago: focused erosion in valleys triggers the rise of mountain peaks due to erosional unloading and isostatically driven uplift. In addition to this interaction between localized erosion and ridgeline uplift, precipitation gradients due to orography introduce additional complexity. Amplified by rising ridgelines, the plateau slope forms a strong orographic barrier with wet conditions at the windward and dry conditions towards the plateau center. This in turn affects the spatial pattern of erosion and isostatically driven uplift.
We propose that the co-evolution of topography and precipitation (a) controls the spatial distribution and maximum height of mountain peaks that prominently tower above the plateau elevation and (b) limit the longevity of orogenic plateaus. In this study, we compare the spatial distribution of mountain peaks along the Tibetan Plateau with results of a numerical model. The model considers orographic precipitation based on the advection and diffusion of moisture and its reaction on topographic barriers, fluvial erosion based on the stream power law, and flexural isostasy including viscous relaxation to account for erosional unloading and isostatic compensation. Our findings reveal that climatic factors (i.e. how far precipitation extends over the ridgeline), tectonic conditions (i.e. the pace and spatial pattern of plateau uplift) and lithospheric parameters (i.e. length-scale of lithospheric flexure) represent principal controls of the coupled precipitation-topography system. Only a few parameter combinations lead the evolution of peaks exceeding 8 km while maintaining the longevity of the plateau in the rain shadow of the ridgeline. Our experiments show that rapid plateau uplift is required, so that the main precipitation falls on the southern slope of the plateau even in the early phase of topography evolution. The longevity of the plateau requires the formation of a drainage divide in the rain shadow immediately behind the ridgeline of the highest mountains. Whether a drainage divide forms and where its position is depends on the ratio of the length scales for lithospheric flexure and orographic precipitation. Without the emergence of such a drainage divide, the plateau is rapidly dissected by river systems, without the formation of mountain peaks exceeding 8 km.
How to cite: Robl, J. and Hergarten, S.: From plateaus to mountain peaks: identifying climatic and tectonic controls on peak elevation and plateau longevity, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3430, https://doi.org/10.5194/egusphere-egu25-3430, 2025.
Fluvial erosion and deposition rates are influenced by channel slope, upstream water discharge, and sediment flux. In mountain belts, fluvial processes primarily generate sediment through the incision of bedrock, with the eroded material being transported downstream by the fluvial discharge. As sediment reaches the low-gradient foreland basin, the reduced channel slope significantly diminishes the river's transport capacity, resulting in part of sediment being deposited in the basin, while the remainder is transported further through the basin's drainage network, eventually reaching more distant locations such as oceans or large lakes. The processes of sediment generation, transfer, and preservation are highly sensitive to precipitation rate change. Therefore, variations in sediment flux within rivers and changes in basin sediment thickness can provide insights into past climate conditions.
Using a fluvial erosion-deposition landscape evolution model, we investigate how erosion-dominated regions (mountain belts) and deposition-dominated areas (foreland basins) respond to periodic variations in precipitation rates. The model results indicate that landscape response is highly sensitive to the ratio of forcing period (P) to response time (τ). Mountain regions typically respond to medium- to high-frequency signals in the form of fluctuations in sediment flux, which can be amplified through sedimentation processes. As the forcing period increases, peak sediment flux and peak precipitation rates may become in-phase, lag, or lead. These differences result from variations in the migration distance of knickpoints, as demonstrated by river elevation profiles and χ-plots. In contrast, basins are more responsive to low-frequency signals in the form of changes in sediment thickness, with basin elevation adjustments consistently lagging behind the forcing. Our work provides insights into understanding the response of the mountain-basin system to precipitation rate variations on different time scales and offers explanations for their different responses to precipitation rate change.
How to cite: Yuan, X., Luo, T., and Shen, X.: Diverse responses of coupled mountain-basin system to periodic climate change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15072, https://doi.org/10.5194/egusphere-egu25-15072, 2025.
The rates and kinematics of tectonic processes are generally thought to be reflected in the resulting landscape - with sites of rapid burial and exhumation typically being more rugged or high-relief. Although the plate boundary transition that occurs at the Mendocino triple junction (MTJ; northern California) represents a fundamental plate boundary change from subduction to translation, the landscape of the northern California coast ranges is relatively subdued or low-relief. Additionally, the MTJ region is marked by high levels of seismicity indicating significant active deformation, but at the surface the effects are relatively minimal. At present, the MTJ region is characterized by an abrupt change in crustal structure from a small, but deep, sedimentary basin - the Eel River Basin (ERB), north of the triple junction, to the exhumed Franciscan subduction complex (basement) to the south.
New crustal seismic tomography for the region coupled with new low-T thermochronologic data and existing geophysical data (heat flow, seismicity, gravity) allow us to understand the cause of this basin-basement juxtaposition. Based on integrative modeling of the thermochronologic data with heat flow and other thermal indicators (vitrinite reflectance) we conclude that the ERB - Franciscan crust system migrates with the MTJ and represents the sequential occurrence of two extreme tectonic events. The ERB forms in advance of the MTJ, filling rapidly over a few million years to a maximum thickness of ~8-10 km. This basin is then rapidly exhumed and eroded in ~ 1 million years as the MTJ migrates, with exhumation rates on the order of order 8-10 mm/yr. In spite of these extreme exhumation rates, the resulting landscape is quite subdued, as a result of the migrating locus of tectonic activity, which leads to extreme but short-lived tectonic activity at any single location as the plate boundary system migrates. The Franciscan basement rocks record this burial/exhumation thermal history, but the lack of significant relief means that such tectonics could be easily missed in investigations of plate boundary evolution.
How to cite: Furlong, K. P., McKenzie, K., and Herman, M.: Hidden Extreme Rate Burial/Exhumation in a Migrating Basin-Orogen System at the Mendocino Triple Junction, California, USA, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12310, https://doi.org/10.5194/egusphere-egu25-12310, 2025.
Geomorphological approaches are essential for advancing our understanding of fault dynamics and assessing better their seismic hazard, especially offshore where direct geological observations are inherently challenging. This study employs high-resolution bathymetric data (1 m) to conduct a detailed quantitative morphometric analysis of individual fault scarps along the North-South Faults (NSF). Our analysis provides a comprehensive characterization of this fault system, including key morphotectonic features such as tectonic depressions, horst and graben structures, half grabens, and pockmarks. Specifically, the fault scarps morphometric analysis derived from evaluating diverse bathymetric profiles across each fault scarp, reveals distinct patterns of vertical displacement, fault growth, and connectivity along the NSF. Vertical displacement ranges from centimetres to decametres, with the largest scarp and fault displacements consistently located in the southern area. This spatial distribution highlights a progressive northward propagation of the fault system, reflecting its evolving dynamics. The presence of relay ramps, stepovers, and interconnected segments indicates that the NSF is an incipient fault system developing within a left-lateral transtensional regime. Our findings support the interpretation of the NSF as the northern extension of the Al-Idrissi Fault, emphasizing its role within the broader tectonic framework of the Alboran Sea. Furthermore, the potential connection between the faults within the NSF suggests that this system could generate earthquakes up to magnitude Mw 6.1. Considering this, and based on the proposed location and the calculated focal mechanism of the 1910 Adra earthquake, we also hypothesize that the NSF may represent an alternative source for this event. This research highlights the importance of surface process analysis in unravelling fault evolution and its broader implications for regional geodynamics.
How to cite: Canari, A., Perea, H., and Martínez-Loriente, S.: Deciphering the dynamics of the North-South Faults in the Alboran Sea (Western Mediterranean) based on a high-resolution morphometric analysis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4463, https://doi.org/10.5194/egusphere-egu25-4463, 2025.
The topography of Madagascar reflects a dynamic history of water divide migration, driven by rifting on both coasts, but modified by late Cenozoic volcanism and extensional tectonics. These geological events have produced distinct geomorphic landscapes and histories. We reconstruct how rifting created coastal escarpments, as well as long-wavelength tilting, that shifted the water divide, changing drainage area and erosion patterns since Cretaceous rifting. We document a westward-tilted plateau with sinuous remnant escarpments on the western margin and a linear escarpment approximately corresponding to the modern drainage divide on the eastern margin, formed during the corresponding rifting phases, separated by 80 Ma. We suggest that the western topographic remnants are part of the older, western escarpment that was destroyed during Indian Ocean rifting, which formed the younger, eastern escarpment and tilted the existing topography, causing the water divide to jump to the eastern margin. Currently, the eastern escarpment corresponds to the insular water divide in the south, but not in the central or northern regions, where the escarpment corresponds to a large, regional knickzone, several tens of kms downstream from the water divide. We argue that knickzone-type river profiles correspond to the late Cenozoic volcanic and tectonic activity that shifted the divide inland from its post-rifting position at the escarpment. These findings highlight the profound, long-term impact of drainage divide migration in shaping Madagascar’s topography and hydrology.
How to cite: Clementucci, R., Uchusov, E., Wang, Y., and Willett, S.: Madagascar's landscape evolution: a tale of two rifts and drainage divide migration, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18815, https://doi.org/10.5194/egusphere-egu25-18815, 2025.
With the advent of increasing computational resources, 3D geodynamic models have become more complex, for example by coupling with various types of surface process models. This allows us to model highly 3D tectonic settings more accurately, such as continental corner collisions. Such settings are sensitive to surface-tectonics interactions. However complex numerical models may be, they are only useful if we can compare them to observations. Burial-exhumation cycle or PT-t (pressure, temperature, time) analysis is one of the few ways of comparing model evolution to nature. It is common in 2D studies, but has barely been used in 3D modelling studies (Fischer et al., 2021).
Here we showcase our newly developed post-processing analysis that accurately tracks markers’ position and properties and the surface above it either forward or backward in time. We apply this method to high-resolution 3D models of the eastern corner of the India-Asia collision, conducted with I3VIS-FDSPM(Gerya & Yuen, 2007; Munch et al., 2022). In these models a strongly curved structure with high exhumation (a syntaxis) develops similar to the Eastern Himalya Syntaxis (Burg et al., 1998). We vary controlling parameters such as surface process intensity to measure their effects on exhumation and metamorphic evolution.
Our novel analysis reveals that exhumation can take place perpendicular to the direction of convergence (termed lateral exhumation) under certain conditions and that rocks can undergo multiple cycles of burial-exhumation under continued convergence. We also quantify the partitioning between surface-driven and tectonically driven exhumation.
Burg, J.-P., Nievergelt, P., Oberli, F., Seward, D., Davy, P., Maurin, J.-C., Diao, Z., & Meier, M. (1998). The Namche Barwa syntaxis: Evidence for exhumation related to compressional crustal folding. Journal of Asian Earth Sciences, 16(2), 239–252. https://doi.org/10.1016/S0743-9547(98)00002-6
Fischer, R., Rüpke, L., & Gerya, T. (2021). Cyclic tectono-magmatic evolution of TTG source regions in plume-lid tectonics. Gondwana Research, 99, 93–109. https://doi.org/10.1016/j.gr.2021.06.019
Gerya, T. V., & Yuen, D. A. (2007). Robust characteristics method for modelling multiphase visco-elasto-plastic thermo-mechanical problems. Physics of the Earth and Planetary Interiors, 163(1), 83–105. https://doi.org/10.1016/j.pepi.2007.04.015
Munch, J., Ueda, K., Schnydrig, S., May, D. A., & Gerya, T. V. (2022). Contrasting influence of sediments vs surface processes on retreating subduction zones dynamics. Tectonophysics, 836, 229410. https://doi.org/10.1016/j.tecto.2022.229410
How to cite: van Agtmaal, L., Balázs, A., May, D., and Gerya, T.: 4D burial-exhumation patterns in a continental corner collision: insights from coupled 3D numerical modelling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18879, https://doi.org/10.5194/egusphere-egu25-18879, 2025.
The Tibetan Plateau, often referred to as the ‘Roof of the World,’ is the largest and highest orogenic plateau on Earth, shaped by the Cenozoic collision between the Indian and Asian plates. Despite its high-elevation, low-relief topography, the timing and spatial variability of uplift across different regions remain topics of significant debate. Earlier models suggested uniform plateau-wide uplift, but emerging evidence points to diachronous evolution. This study presents the first thermochronological constraints on the tectonic history of the northwestern Tibetan Plateau within the western Songpan-Ganzi terrane, a region previously lacking detailed investigation. Apatite fission track and apatite (U-Th)/He dating of Mesozoic basement rocks from the Hehribaé Tso and Keliya regions identify a phase of moderate to rapid exhumation from the late Eocene to Oligocene, followed by prolonged Neogene tectonic stability. Thermal history modeling indicates that this sector of the plateau reached near-modern topography by the late Oligocene, earlier than the Hoh-Xil region to the east, where uplift persisted into the Miocene. This asynchrony highlights spatially heterogeneous plateau growth, challenging the notion of uniform uplift and emphasizing the role of localized tectonic processes in plateau evolution. The findings refine models of continental deformation and plateau stabilization, offering new insights into the mechanisms controlling orogenic plateau dynamics.
How to cite: He, Z.: Neogene stabilization of the northwestern Tibetan Plateau, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7190, https://doi.org/10.5194/egusphere-egu25-7190, 2025.
Western Turkey underwent episodic N-S extension following a Late Cretaceous–Paleogene compressional regime. This extension resulted in the formation of the N-S-oriented Selendi and Gördes basins, as well as the E-W-trending Alaşehir Basin. However, the timing of basin formation is debated, hampering geodynamic model development or links to causal mechanisms. Here, we test whether N-S- and E-W-trending basins formed synchronously by determining maximum depositional ages from detrital zircon or stratigraphic ages from zircon-bearing tuffs in the basin fill of the Gördes and Alaşehir Basins.
Existing basin chronology for the Gördes Basin is inferential and inconsistent. Previous research suggests the onset of sediment accumulation in the Gördes Basin occurred between 24.1 and 21.7 Ma. However, the older age is based on K-Ar dating of dikes that cross-cut the basement of the Gördes Basin and are lithologically correlated to clasts in the lower basin fill. The younger age comes from the tuffaceous uppermost formation and, therefore, represents a minimum age for the basin fill. K-Ar ages from volcanic domes underlying the oldest stratigraphy in the center of the Gördes Basin range from 18.4 ± 0.8 Ma to 16.3 ± 0.5 Ma, implausibly implying they erupted after the surrounding basin fill was deposited. This discrepancy suggests that either the age of the basin fill or the conclusion that the igneous rocks are volcanic is incorrect.
The age of the Alaşehir Basin is based primarily on palynological biostratigraphy and magnetostratigraphy. Both yield middle Miocene ages (~16.4–14.4 Ma), but it is unclear whether these represent the oldest stratigraphy in the basin. Detrital zircon provenance data indicate that the earliest basin-filling sediments in the Gördes Basin were derived from a mixture of sources with affinities to the Tauride and Anatolide belts. Sediment provenance changes rapidly upsection, and within 50 meters, the Anatolide source is absent. In the Alaşehir Basin, the Anatolide source is never present, and sediment provenance is dominated by Tauride sources from the onset of basin filling.
Preliminary chronostratigraphic data indicate that the onset of sediment accumulation in the Alaşehir and Gördes basins may be synchronous but also highlight significant problems with the stratigraphic model for the Gördes Basin. Data from a sandstone in what is considered the lowermost formation of the Gördes Basin yield a maximum depositional age of 17.5 ± 0.2 Ma, younger than the oldest reported K-Ar ages of 21.7–20.5 Ma. A stratigraphically higher tuffaceous sample from the same formation yields an upward-younging age of 16.9 ± 1.7 Ma. However, two ignimbrite samples from what is considered a younger formation yield ages of 18.2 ± 2.8 Ma. These age inversions and stratigraphic inconsistencies indicate significant issues with the stratigraphic model for the basin. In comparison, a sandstone sample from the lowermost formation of the Alaşehir Basin yields an age of 19.0 ± 2.9 Ma. We conclude that the onset of sedimentation in the two basins is synchronous within the resolution of our methods, but significant work is needed to determine more precise basin chronologies and resolve apparent age inversions in the Gördes Basin.
How to cite: Ozyalcin, C., Guan, X., Saylor, J., and Erkızan, L.: Detrital Zircon Geochronology Indicates Synchronous Evolution Of Western Anatolian Supradetachment Basins, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1137, https://doi.org/10.5194/egusphere-egu25-1137, 2025.
How the ultrahigh-pressure (UHP) terranes are exhumed to shallow levels is among the most interesting but challenging topics in geosciences. In particular, little is known about how do climate-driven surface processes contribute to the UHP terrane exhumation. We investigate the paleolatitudes where the UHP terranes were exhumed. Our results show that all the UHP terranes in continental collision zones or oceanic accretionary wedges were exhumed within low latitudes (0°–30°), and the average paleolatitude for exhumations of the investigated 43 UHP terranes is ~5.1° N. Given that high temperature and precipitation of low latitudes would cause intense denudation, more sediment input at low latitudes into subduction zone could not only increase the buoyancy of deeply subducted mafic-ultramafic rocks, but also lubricate the subduction zone and reduce the downward friction in subduction channels, finally making it easier to exhume UHP rocks in low latitude regions. In contrast, those UHP xenoliths in mantle-derived igneous rocks could be brought to surface at higher paleolatitudes. Furthermore, the pattern of frequency for the UHP terranes exhumed at convergent boundaries is consistent with that of interglacial stages throughout the Earth history, indicating that the UHP exhumation is also controlled by the climate and thus suggesting that the exhumed UHP terranes may be useful paleoclimate indicators.
How to cite: Yan, L., Zhang, K., Zeng, L., and Gao, L.-E.: Paleolatitudes of the UHP terrane exhumation: Implications for interaction with climate-driven surface processes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14529, https://doi.org/10.5194/egusphere-egu25-14529, 2025.
Orogenic growth, characterized by formation and forward propagation of foreland fold-thrust belts, is a process predicted by wedge models of thrust sheet systems. During this process, the drainage network is disrupted by differential uplift and shortening across thrust ramps and lateral structures linking thrusts. Transverse rivers are often diverted into longitudinal reaches parallel to thrust faults, where they converge into larger river systems, thereby altering the river network patterns. Whether these patterns contain fingerprints of past tectonic events can be elucidated through numerical modeling of coupled tectonics and river network evolution.
To investigate the effects of isolated thrust sheet propagation on drainage networks, we use a numerical two-dimensional landscape evolution model, the Divide and Capture model (DAC), which integrates numerical solution of fluvial incision and analytical hillslope processes for both diffusive and slope-limited processes on an adaptive grid. As a Lagrangian reference-frame model, river channel courses are accurately tracked, even with topographic advection. We model a growing bivergent, orogenic wedge as a shortening region with multiple isolated thrust sheets, consisting of a shortening structure with flat-ramp-flat geometry. Faults have finite strike length and strike-slip linking structures, constructed to build a strain-compatible model with equal convergence along strike. Convergence velocity is oriented perpendicular to the thrust sheets and is absorbed by each fault through a specified slip rate.
The modeling results reveal a non-steady and dynamic landscape, characterized by locally high uplift rates and significant relief above ramp structures. The river network responds dynamically to the propagation and displacement of thrust sheets. Interestingly, the largest transients and river capture events are not associated with the uplift zones, but rather with the strike-slip linking structures. Rivers draining the uplift blocks are relatively stable, but longitudinal rivers parallel to thrusts are often blocked, forming unstable closed basins or are forced to cross transfer structures, undergo significant offset and eventual river capture events. We conclude that horizontal advection, and its variation across a complex 3-D fold-and-thrust system, rather than localized uplift, dominates the reshaping of a river network above the propagated thrust foreland.
How to cite: Jiang, Y., Wang, Y., Willett, S. D., and Lu, H.: River network response to thrust sheet propagation into a foreland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14794, https://doi.org/10.5194/egusphere-egu25-14794, 2025.
We present a backwards-in-time approach for both linear and non-linear cases of the stream power (SP) equation to constrain uplift, erosional histories, and paleo-topography. Our approach does not assume that every source of change in a river profile can be accounted for. Instead, we use existing dynamic topography models, coupled with a backward-in-time erosion model and flexural isostasy, to focus on the large-scale perturbations affecting the river profile. This allows us to resolve best-fit dynamic topography models based on observed stream profiles. Here, we focus on the Western Highlands of Cameroon, a slow-eroding setting which is thought to have undergone large-scale topographic changes since at least the Miocene, due to its proximity along the enigmatic Cameroon Volcanic Line (CVL). We show that large scale perturbations (knickzones) in 3 of the largest rivers draining the highlands south of the CVL can be explained by up to 400 m of relative uplift due to dynamic topography over the past 30 Myr. These models suggest that a mantle source is largely responsible for recent uplift in the CVL region, as opposed to a purely lithospheric process suggested by others.
How to cite: Ruetenik, G. and Moucha, R.: Backwards-in-time river profile modeling: constraints on Dynamic Topography in the Western Highlands of Cameroon, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18423, https://doi.org/10.5194/egusphere-egu25-18423, 2025.
The western Colombian Andes comprise several intermontane and forearc basins, whose evolution has been closely related to the growth of the Central and Western Cordilleras. Available tectonostratigraphic constraints suggest a highly asymmetrical Neogene basin evolution, characterized by limited connectivity among depocenters and a localized sedimentary provenance. Such a configuration is interpreted as the product of the along-strike tectonic segmentation of the Pacific continental margin, as indicated by the presence of contrasting subduction geometries and the occurrence of spatially variable morpho-structural and magmatic styles along the Colombian Andes. It is still uncertain whether spatiotemporal variations in subduction geometry remain a primary driver of recent landscape evolution, or whether there are other significant controlling factors, such as lithological and structural variations, and climatic or vegetation gradients. Here, we use catchment-averaged denudation rates and morphometric analyses of the Colombian Western Cordillera to evaluate the along- and across-strike symmetry of recent erosion patterns, temporal variations in rock uplift, and their primary controls. We also integrate available geomorphological data and erosion rate estimates for the Central Cordillera to assess the drivers of the asymmetric tectono-structural and topographic configuration of the western Colombian Andes. We intend to highlight the value of combining morphometric, structural, and sedimentological data to identify the impacts of tectonic, magmatic, and surface processes on landscape evolution across multiple temporal scales
How to cite: León, S., Faccenna, C., and Schildgen, T.: Drivers of asymmetric morpho-structural evolution along the western Colombian Andes across multiple temporal scales, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14415, https://doi.org/10.5194/egusphere-egu25-14415, 2025.
Crustal deformation is highly influenced by surface processes, such as erosion and sedimentation, particularly in tectonically active regions. While these processes have been intensively studied in large-scale erosive settings and tectonically active areas, the specific effect of river incision on valley morphology and crustal deformation remains poorly constrained. In this study, we show that valley incision can have a significant impact on the morphological and tectonic evolution of orogenic systems. Using a two-dimensional thermo-mechanical model and inspired by the case study of the Nanga Parbat Haramosh Massif (NPHM), we investigated the effects of varying incision rates and topographic diffusion coefficient on crustal deformation in the absence of imposed tectonic boundary forces. Our results indicate that with the lowest incision rates (between 10 and 70mm.yr-1), surface processes predominantly govern the morphology of the valley, with limited tectonic feedback. Conversely, at higher incision rates (over 90mm.yr-1), the tectonic response becomes increasingly significant, impacting the long-term regional deformation and the morphology of the valley. Over a timescale of 10 million years, this dynamic interplay can lead to substantial crustal deformation involving the exhumation of the lower crust (at rates up to 3mm.yr-1) . Our reference model is in very good agreement with natural observations from the NPHM, suggesting that valley incision alone can drive significant crustal deformation, even in the absence of far field stresses (shortening). These results offer valuable insights into the interplay between surface processes and crustal deformation, highlighting the critical role of river incision in shaping mountainous landscapes and promoting the exhumation of deep crustal materials in actively deforming orogenic areas.
How to cite: Geffroy, T., Yamato, P., Steer, P., Guillaume, B., and Duretz, T.: Impact of river incision on lower crustal flow: insights from thermo-mechanical models, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8734, https://doi.org/10.5194/egusphere-egu25-8734, 2025.
The Yenişehir Basin, located in northwestern Türkiye, is a major geological structure formed by complex tectonic processes. This study focuses on the evolution of the basin and examines the structural and morphometric features, tectonic activity, and geophysical results. The active southern branch of the North Anatolian Fault Zone (NAFZ) has been responsible for formation of the Yenişehir Basin as a pull-apart basin. The rotation of the surrounding uplift areas, especially the Gemlik-İznik and İnegöl-Bilecik uplifts, played a crucial role in the development of the basin. The morphometric analysis of the study highlights the impact of tectonic activity on the topography of the basin, including the presence of features such as pressure ridges, relict hills, stream offsets and alluvial fans. Structural elements, including the Yenişehir Fault Zone, the Hayriye-Ayaz Fault and the Sungurpaşa Fault Zone, contribute to the boundaries of the basin and its ongoing tectonic evolution. Gravimetric analyzes confirm an increase in gravity anomalies within the basin, consistent with tectonic activity and structural evolution. In addition, the relative tectonic activity levels provide valuable insights into the evolution of fault systems and their influence on the geomorphology of the region. The results highlight the ongoing tectonic processes, including the extension of the basin and the role of faults in shaping the topography, and contribute to our understanding of the dynamic geological history of the region.
How to cite: Taş, K. Ö., Beyhan, G., and Selim, H. H.: Morphotectonic Analysis of the Yenişehir (Bursa) Pull-Apart Basin , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8331, https://doi.org/10.5194/egusphere-egu25-8331, 2025.
The Northern Alpine Foreland Basin (NAFB), also called Molasse basin, records the geological evolution of the Alpine orogenic belt. The basin accumulated sediments almost continuously for over 25 Myr, beginning in the Eocene. However, sedimentation ceased approximately at 5 Ma, accompanied by the erosion of up to several kilometres of sediments. The cause of this drastic shift in basin dynamics remains elusive.
Data suggests that the erosion pattern of the NAFB vary spatially and temporally and are unlikely to be explained by a single mechanism. Preliminary findings suggest that internal (i.e. Alpine) tectonics might play a primary role. Significant erosion in the western part of the basin correlates with pronounced vertical tectonic activity, including uplift associated with the thrusting of the Jura Mountains and subsidence due to the bending of the upper plate. In contrast, areas of lower erosion in the central basin correspond to more limited thrusting of the Alpine front and moderate subsidence of the basin. Meanwhile, the eastern basin likely experienced erosion earlier in its history, possibly driven by tectonic reorganisation and the cessation of convergence.
These interpretations are, however, based on correlations, and the quantitative impact of these tectonic movements on sedimentation dynamics has yet to be tested. Similarly, other external factors — such as tectonic activity in the European Cenozoic Rift System, filling of the Pannonian basin, climatic changes, and base-level shifts related to the Messinian Salinity Crisis — and their compounding effects must be tested.
Here, landscape evolution numerical modelling is used to better understand the basin dynamics. The goSPL code allows to model landscape evolution at continental scale accounting for different tectonic, climatic, and sea-level forcing conditions. This code is used to test the relative contributions of both internal and external mechanisms mentioned above and their interactions. The anticipated results will provide a quantitative assessment of the relative contributions of these factors on the dynamics of the Northern Alpine Foreland Basin since the Miocene.
How to cite: Rime, V. and Salles, T.: The demise of the Northern Alpine Foreland Basin: what caused its erosion?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4308, https://doi.org/10.5194/egusphere-egu25-4308, 2025.
Numerical modelling is widely used to investigate subduction dynamics, but the relative contribution of different parameters, such as convergence rates, lithosphere rheology and the surface mass redistribution by surface processes, in driving the overriding plate topographic evolution and overall strain remains elusive. We investigate the behaviour of the overriding continental plate during ocean-continent subduction by an extensive parametric study on key physical parameters using a 2D fully coupled thermo-mechanical and landscape evolution numerical model.
The examined parameters include the convergence rate, different crust, mantle and thermal lithospheric thicknesses, and erosion rates, also accounting for asymmetric orographic effects. Our modelling results show that a fast convergence velocity (>5 cm/yr) and a thick sub-continental lithospheric mantle promote compression of the overriding continental plate in the initial stages of subduction, when the slab dip angle is gentle, and back-arc extension during advanced stages. Conversely, a slow convergence velocity (1 cm/yr) and a thin sub-continental lithospheric mantle promote widespread extension since the initial stages of subduction, with wide back-arc extension. However, erosion and orographic effects can drastically change the subduction dynamics and associated overriding plate strain distribution, with particular effects on the location, size and fate of continental fragmentation due to back-arc extension and rifting. This continental fragmentation may produce microcontinents whose fate can change in response to the investigated parameters. Our extensive parametric study highlights hitherto unrecognized dynamics such as erosion-induced microcontinent subduction, with strong implications for plate kinematic reconstructions and our current understanding of tectonics-climate interactions.
How to cite: Caso, F., Giuntoli, F., Petroccia, A., Pilia, S., and Sternai, P.: Assessing the role of convergence rate, lithospheric thickness and surface processes in affecting subduction dynamics with 2D thermo-mechanical numerical modelling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7952, https://doi.org/10.5194/egusphere-egu25-7952, 2025.
It is well documented that many mountain belts, like the Pyrenees, European Alps, Greater Caucasus, or Atlas, form to a large degree by the inversion of pre-collisional extensional basins. Looking at present-day extensional systems, we observe that one of their first order characteristics is rift segmentation with offset sub-basins that are linked through transfer zones. However, the impact of rift segmentation and linkage structures on subsequent mountain building remains unknown. Here, we use the 3D thermo-mechanical geodynamic model pTatin3D that is coupled to the fluvial landscape evolution model FastScape to investigate the effects of offset rift basins on subsequent basin inversion and mountain building. Presenting numerical models and a work minimization analysis, we show that rift linkage during extension depends on rift basin offset. The inversion of offset rift basins during mountain building can be subdivided into a juvenile and a mature stage. During the juvenile stage, extensional structures are reactivated, forming a mountain belt that resembles the basin structure. Further growth during the mature stage is determined by the emerging subduction polarity, which depends on pre-collisional basin offset and the nature of pre-existing weaknesses. Small offsets or pre-existing weaknesses that dip in the same direction lead to same-polarity subduction, which preserves the extensional template in the mountain belt. Basin offsets larger than ~30 km favour opposite polarity subduction, which eradicates the pre-collisional basin structure. Based on first-order model characteristics, we propose a simple template, in which mountain belt topography and dominant valley orientations can be used to infer deformation at depth. Comparison with the Greater Caucasus, Atlas, and Pyrenees shows that the Greater Caucasus is a type-example of a mature same-polarity subduction orogen, the Atlas is a juvenile inversion orogen where subduction polarity does not play a significant role, and the Pyrenees are a mature same-polarity orogen, which exhibits several additional complexities.
How to cite: Wolf, S. G., Huismans, R. S., Muñoz, J. A., and May, D. A.: Modelling the influence of pre-collisional rift linkage during mountain building, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16005, https://doi.org/10.5194/egusphere-egu25-16005, 2025.
The influence of evaporites on the tectonic style of rift basins, as well as subsequent basin inversion and fold-and-thrust belt evolution, has gained increasing attention from both the scientific community and industry. Salt deposits play a crucial role in hydrogen and CO₂ storage and are associated with geohazards such as landslides. Despite this, the impact of pre-rift décollement layers on the subsidence, thermal evolution, fault spacing, rift linkage, and erosion-deposition patterns throughout the Wilson cycle remains insufficiently explored.
This study employs high-resolution (300–400 m), lithospheric-scale 3D thermo-mechanical models using I3ELVIS to simulate the successive stages of rifting and subsequent contraction. The models incorporate simplified erosion and sedimentation processes through diffusion, with a specific focus on the role of pre-rift evaporitic décollement layers. An low-viscosity evaporitic layer is defined at the base of the pre-rift sedimentary sequence, and the effects of varying evaporite thickness, density, and erosion-sedimentation rates are systematically analyzed. Plate divergence, simulating a 2 cm/yr lithospheric extension rate, transitions to a 1 cm/yr convergence rate to model basin inversion. Extension-to-contraction transitions are implemented after varying degrees of extension, either during continental rifting or following crustal break-up.
The rift basins in the models exhibit diverse salt tectonic structures, including salt diapirs, minibasins, and rollover structures. Additionally, localized contractional structures form along the tilted flanks of half-graben depocenters. Basin inversion reactivates salt structures along inherited basin margins, promoting the development of diapirs above the rising orogenic core. Thin-skinned thrust sequences are efficiently decoupled from basement-involved structures by the inherited evaporitic décollement layer. Although the models are not site-specific, the results align with observations from rifted (passive) margins and regions such as the Atlas and Carpathians Mountains.
How to cite: Balázs, A.: Salt Tectonics During Lithospheric-Scale Rift and Basin Inversion Stages: Insights from High-Resolution Numerical Modeling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20012, https://doi.org/10.5194/egusphere-egu25-20012, 2025.
The tectonic framework of Northern Italy is characterized by the complex interaction between the south-verging Southern Alps, the north-verging Northern Apennines, and their shared foreland basin, the Po-Plain Basin. The Neogene evolution of the Northern Apennines gives rise to three buried structural arcs, each one with an increasing amount of shortening, from W-E, the Monferrato arc, the Emilian Arc, and the Ferrara arc. The eastern Emilian Arc is composed of three main thrust systems and related anticlines that, from south to north, are named Stradella-Belgioioso, San Colombano and Casalpusterlengo-Zorlesco structures, and the Caviaga-Soresina structures. The western Emilian Arc is defined by the prolongation of the Caviaga-Soresina, Cortemaggiore and Salsomaggiore structures. In the outcropping Northern Apennines, the Bobbio Tectonic Window preserves a record of the interactions between the buried front of the Emilian Arc with the buried front of the Southern Alps.
Existing studies have focused on fault slip rate reconstructions based on the interpretation of seismic lines along the Emilian arc, but a comprehensive 3D model of the entire arc is still lacking. We developed a model that integrates the structural and exhumation history of the Emilian Arc and the Southern Alps.
Our study sheds important information on the spatio-temporal evolution of the Bobbio Tectonic Window, with implications on our understanding of out-of-sequence deformation in the Northern Apennines. Specifically, more than 1300 TWT seismic reflection profiles and 200 wells with log information and 42 wells with time-depth curves (courtesy of ENI E&P), have been integrated to build a detailed 3D tectonic model of the Emilian Arc. A set of balanced cross-sections were also developed to calculate fault slip rates. Moreover, sandstones from the core of the Bobbio Tectonic Window (San Salvatore Sandstones) were analyzed for apatite (U-Th)/He low-T thermochronology to 1) constrain cooling and exhumation history, 2) assess relationships between deformation and exhumation of the Emilian Arc in response to Alps-Alpine tectonics.
Our preliminary thermochronological results from the Bobbio Tectonic Window show a Pliocene cooling signal between ca. 2 and 4 Ma. We interpret these results to represent out-of-sequence thrusting within the inner Apennine fold-and-thrust belt as a result of the collision between the frontal part of the Emilian Arc with the Southern Alps. This study shows how far field geological structures can influence the kinematics of thrust systems and helps explain the generally decreasing Plio-Pleistocene tectonic activity of the Northern Apennine's buried thrust front.
How to cite: Barrera, D., Stendardi, F., De Matteo, A., Bellotti, P., Pezzoli, S., Toscani, G., Carrapa, B., and Di Giulio, A.: A window into Alps and Apennines interactions and the development of the Northern Apennines fold-and-thrust belt, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3296, https://doi.org/10.5194/egusphere-egu25-3296, 2025.
The basement nature of Junggar Basin is an important topic concerning the basin evolution and continental growth of CAOB, but it still remains highly controversial, with views varying from the existence of pre-Cambrian basement as its continental block to a basement of Paleozoic oceanic crust or oceanic island arc complexes. Here, we focus on the deep architecture of Junggar Basin and its nature, using deep seismic reflection together with zircon Hf isotopic analysis carried out on Late Paleozoic strata, in order to provide new constraints on the basement nature of Junggar Basin. Most Carboniferous volcanic rocks, obtained from seven wells within Junggar Basin, have positive εHf(t) values except for minor negative εHf(t) values in the western Junggar Basin, suggesting that the Junggar Basin is mainly dominated by juvenile crust without the large-scale pre-Cambrian basement, if exist, it is limited and only located in the western part of Junggar Basin. Moreover, the 2D seismic profile suggests that Junggar Basin has duplex basement structure according to the differences in wave velocity. The upper part is Hercynian folded basement, whereas the lower part is the ancient crystalline basement. Furthermore, the deep seismic reflection profiles and drilling data confirm that the basement of Junggar Basin is chiefly composed of Hercynian folded basement. These Hercynian volcanic rocks have typical arc-like geochemical characteristics with low TiO2 contents, enrichment in LILEs and depletion in HFSE, suggesting that they are products of subduction-related magmatism. These results, in combination with previous data in the East and West Junggar terrane, imply that the Junggar Basin probably have a collaged basement of Paleozoic juvenile crust with limited pre-Cambrian basement.
How to cite: Li, D. and He, D.: Appraising the basement nature of Junggar Basin through borehole core and deep seismic reflection data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15026, https://doi.org/10.5194/egusphere-egu25-15026, 2025.
Slab detachment and its lateral propagation (slab tearing) have been hypothesized to cause along-strike migration of foreland basin depocenters, sedimentary facies belts and adjacent mountain uplift in many collisional orogens. However, existing numerical models of continental collision suggest that lateral propagation of slab tearing is a geologically very fast process (up to 120 cm yr-1), often inconsistent with tear velocity estimated from foreland basin depocenter migration data ( <20 cm yr-1). Moreover, the spatial and temporal effects of slab tearing on surface processes including the along-strike differential evolution of foreland basins and lateral facies belt migration remain poorly understood. Here, we present 3D thermo-mechanical numerical models, coupled with surface processes, such as diffusion-controlled erosion and sedimentation, to address under what conditions lateral migration of slab detachment along-plate boundaries slows down, if so, how it influences the evolution of foreland basins and the adjacent mountain topography. Our results indicate that lateral crustal heterogeneities, such as micro-continents, can trigger the initiation of slab detachment at one end earlier than the other. However, once a slab tear begins, it propagates to the opposite end almost instantaneously. Strikingly, an asymmetric oceanic age along the strike of the subducting passive margin, resulting in lateral lithospheric strength variations, plays the most significant role in slowing down the lateral propagation of slab tearing (8-12 cm yr-1)—to rates similar to those obtained from collisional orogens. Finally, we compare our model results with Alps-Carpathians mountain chain and adjacent foreland basins, and emphasize the necessity to take into account subducting passive margin’s structural and oceanic age heterogeneities to explain slower slab tear propagation and observed surface geological fingerprints.
How to cite: Maiti, G., Balázs, A., Eskens, L., Gerya, T., and Andrić-Tomašević, N.: Slow Propagation of Slab Tearing at Collisional Boundaries: Implications for Foreland Basin Evolution and Adjacent Mountain Uplift, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8912, https://doi.org/10.5194/egusphere-egu25-8912, 2025.
On December 26, 2004, a 9.1 Mw megathrust earthquake struck along a 1300 km rupture extending from Sumatra to the Andaman-Nicobar region. This event occurred along the Sunda subduction zone, where the Indo-Australian Plate subducts obliquely beneath the Southeast Asian Plate. The oblique convergence has resulted in a sliver fault system comprising the Sagaing Fault, Andaman Sea Transform Fault (ASTF), Andaman Sea Spreading Center (ASSC), Andaman Nicobar Fault (ANF), West Andaman Fault (WAF), and Great Sumatra Fault (GSF). Key morphotectonic features in this region include the volcanic arc hosting Barren Island (BI) and Narcondam Island (NI) and the volcanic-origin Alcock Rise (AR). Additional significant faults include the Diligent Fault (DF), East Marginal Fault (EMF), and Cocos Fault (CF). The ANF, an active strike-slip fault north of the WAF, significantly influences basin morphology and generates earthquakes above 10°N latitude. This study focused on (1) analyzing the geometry and impact of ANF branches on basin morphology and (2) understanding the crustal architecture and the role of underplating in the Andaman volcanics. Three 2D seismic reflection lines between AR and NI revealed a positive flower structure in the basin, indicating the presence of an ANF branch. Fluid evidence was identified within a ~90 km² area at ~650 m depth below the seafloor through velocity, polarity, Q attenuation, and AVA analyses, although well data is unavailable to confirm the fluid type. The findings suggest that fluid migration is influenced by the crustal-scale ANF and associated depocenter variations.
To further explore the crustal architecture beneath NI, BI, and AR, four gravity profiles were extracted from satellite-derived free-air gravity data, followed by forward gravity modeling. The Moho depths beneath BI and NI were found to be ~17.67 km and ~17.58 km, respectively. Beneath AR, the Moho depth varies from 16.4 km to 17 km, reaching 19.4 km north of AR and Narcondam, connecting to the Burma region. The thickness of the underplated layer ranges from 1.5 to 2.7 km beneath AR and is less than 2 km beneath NI. This underplated layer beneath AR likely originates from the magma chamber associated with the Andaman Sea Spreading Center.
How to cite: Srivastav, H. K. and Ghosal, D.: Investigation of Andaman Sea using seismic data and gravity modelling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-304, https://doi.org/10.5194/egusphere-egu25-304, 2025.
The Southern Permian Basins (SPB) have been extensively explored for ore deposits, yet the understanding of remaining undiscovered copper potential remains poorly constrained. This study employs goSPL, an open-source landscape and stratigraphic evolution model, to reconstruct the Permian sedimentary evolution of the Polish Trough in the southeastern SPB. To do so, we integrate paleogeographic reconstructions, sediment provenance analyses, and accumulation processes to assess the impacts of key tectonic events and paleoclimate on basin evolution. We simulate early sediment deposition under six tectonic regimes evaluating their influence on the provenance of the Upper Rotliegend red beds and their potential as a copper source for stratiform sediment-hosted copper deposits in the Kuperscheifer shale. Our results show that a variable subsidence scenario best matches observed sedimentation rates (~200 m/Myr), replicates the ~15 Myr hiatus found in the basin, and accurately captures depositional depth and sediment volumes (~19,000 km³), particularly during periods when the basin subsided below sea level. Provenance analyses indicate that sediments were predominantly sourced from the Bohemian and Carpathian Massifs, with up to 50% originating from the Fenno-Scandian Shield and Carpathian Massif during the Permian. Using paleo-lithology map, we estimate that approximately 1,000 km³ of sediments in the Upper Rotliegend red beds potentially held 50 to 155 Mt of ore which considerably discovered copper resource estimates in the basin. These findings highlight the importance of the red beds as a primary source for the Kupferschiefer copper deposits and suggest the red beds have potential for supplying additional undiscovered copper deposits. The method developed here can be used to assess red bed copper source potential for other basins worldwide, including those in frontier copper regions.
How to cite: Hadler Boggiani, B., Mallard, C., Salles, T., and Atwood, N.: Volume and provenance of sediments in the Rotliegend Polish Trough - Southern Permian Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1278, https://doi.org/10.5194/egusphere-egu25-1278, 2025.
