Positive and negative inversion tectonics have been the subject of intensive study, aiming to understand how inherited geological features control both short- and long-term evolutionary trends. Yet, several key questions remain open: i) How do variations in sequence stratigraphy, the presence of multiple décollements, structural segmentation, and syn-tectonic sedimentation influence collision and rifting processes? ii) How does the thermal evolution of rifting and post-rifting stages affect lithosphere-scale orogenesis and vice versa? iii) How does the rifting style (fast vs. slow, magmatic vs. non-magmatic) shape the structural and chemical character of deep orogenic roots and their subsequent activation as extensional zones? iv) What are the implications for georesources accumulation and preservation?
This session seeks to address these questions through a multidisciplinary lens. We invite abstracts that explore the short- and long-term dynamics, as well as the structural geometry and evolution of rift systems and orogens subsequently involved in positive or negative tectonic inversion, using a range of methodologies—including, but not limited to, structural fieldwork, cross-section construction and balancing, 3D structural modelling, seismic analysis, analogue and numerical modeling, rock mechanics, geomorphology, thermochronology, and geophysical investigations.
Posters on site: Tue, 5 May, 14:00–15:45 | Hall X2
Intraplate lithospheric contractional deformation followed by subduction and continent collision affect oceanic basins and rifted margins during a complete cycle of positive tectonic inversion. Magma-poor rifted margins, in particular, display significant compositional and structural contrasts from continent to ocean that strongly influence the distribution of tectonic structures, especially during the early stages of contractional deformation that precede and/or accompany subduction initiation. The Mesozoic magma-poor Iberian Atlantic margins uniquely recorded contractional lithospheric deformation and aborted, incipient subduction in the Bay of Biscay during the Alpine Orogeny, enabling the investigation of the influence of inherited rift structures in governing the type and spatial distribution of contractional structures. Using seismic images, we map contractional tectonic structures, basement domains, extensional faults and rift basins along the North and West Iberian margins to analyse the rift parameters that conditioned deformation distribution and localisation, with particular emphasis on thrust emplacement.
Along the North Iberian margin, we identified three overlapped multi-stage Mesozoic rift systems that accommodated distinctive types of contractional structures, amplifying the inherited margin segmentation. Halokynetic-related structures developed within a diffuse rift system, whereas mild inversion of pre-existing extensional faults and the formation of reverse faults deforming the sedimentary cover occurred in a transtensional rift system. In contrast, thrusting developed distinctly within a hyperextended rift, consisting of two segments. Continentward-dipping thrusts that sole out in the pre-rift sediments and in the basement, along with inverted oceanward-dipping extensional faults, affected thinned continental crust. Continentward-dipping thrusts deformed and decoupled in the deeper transitional basement, consisting of highly thinned crust and exhumed serpentinized mantle, resulting in basement duplication and thickening. We mapped large thrusts that caused basement and sediment uplift, erosion, and landward backtilting, as well as large thrusts that produced erosion in the frontal part of the thrust sheet. The former are confined to regions of sharp top-basement deepening, suggesting significant crustal thickness variations, while the second are localised in zones of basement-structure changes that may correspond to transitions between different basement types. Distributed thrusts, however, internally deformed the upper part of ultra-thinned transitional basement and soled out at highly reflective levels that may correspond to relicts of ductile lower crust or serpentinized levels within the exhumed mantle. The West Iberian margin exhibits comparable patterns of reverse-fault formation and pre-existing faults reactivation, with extensional faults reactivated within thinned continental crust, and large, newly formed landward- and oceanward-dipping thrusts deforming the transitional basement. Our results show that rift segmentation conditions the type of reactivation along magma-poor rifted margins. Segment boundaries, together with internal variations in crustal thickness and the structure of weak transitional basement along hyperextended rift systems, localise large thrusts that may accommodate significant and potentially underestimated intraplate contractional deformation.
How to cite: Cadenas, P., Manatschal, G., Fernández-Viejo, G., Welford, J. K., C. Duarte, J., and Somoza, L.: The Role of Rift Structure on the Contractional Deformation of Magma-Poor Rifted Margins: Insights from the Reactivated Iberian Atlantic Margins, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14081, https://doi.org/10.5194/egusphere-egu26-14081, 2026.
Continental collision commonly overprints rifted continental margins, such that inherited extensional architecture and mechanical stratigraphy exert first-order controls on strain partitioning during shortening and on the structural pathways exploited during subsequent extension. The Umbria–Marche sector of the Northern Apennines constitutes a well-constrained natural laboratory for addressing these issues, as Neogene shortening of the Adria passive-margin multilayer produced a fold-and-thrust belt that was later dissected by Quaternary normal faulting.
We integrate field structural constraints with regional seismic interpretation tied to boreholes, balanced and restored cross-sections, gravity modelling, and 3D structural modelling. We further quantify fault-system kinematics using along-strike length–displacement profiles and displacement–length scaling derived from the 3D framework. This integrated workflow constrains shortening partitioning between the sedimentary cover and the upper crust and assesses the extent to which inherited rift structures and stratigraphic thickness variations governed thrust segmentation and the subsequent extensional overprint.
Our reconstruction indicates a ramp-dominated contractional style. Shortening was mainly accommodated on moderately dipping thrust ramps that cut through the sedimentary succession and link downwards into the upper crust, without requiring large displacements along a laterally continuous basal décollement within – or at the base of – the sedimentary cover. Thrust-related folding and progressive ramp linkage generated pronounced along-strike segmentation, while shortening was distributed between thrust slip, associated folding, and subsidiary distributed deformation. Along-strike variability is systematic and reflects the interaction between inherited Mesozoic extensional discontinuities and lateral stratigraphic heterogeneity, which preconditioned ramp nucleation, guided linkage pathways, and modulated cover–basement coupling during Neogene shortening. This framework reconciles surface structures with deep crustal architecture independently supported by gravity constraints and is consistent with progressive cover–upper crust coupling and strain localisation within a mechanically heterogeneous carbonate–siliciclastic multilayer.
Quaternary extension is expressed by segmented, high-angle normal fault systems that dissect the pre-existing thrust stack and penetrate the upper crust. Their 3D geometry and segmentation indicate that extension is superposed on – but does not represent a kinematic reversal of – contractional structures. Cross-cutting relationships document limited systematic reactivation of thrust faults under extension, whereas extensional structures are primarily guided by inherited crustal anisotropies and mechanical layering.
Overall, the Umbria–Marche Apennines show how rift-related inheritance promotes ramp-dominated thrusting and segmented fold-and-thrust belt development, while also conditioning the localisation and segmentation of late-orogenic normal faults within a mechanically layered, anisotropic crustal architecture.
How to cite: Pedini, M., Mazzoli, S., Pierantoni, P. P., Cella, F., Di Celma, C., and Zambrano, M.: Rift inheritance controls ramp-dominated thrusting and Quaternary normal-fault geometry in the Umbria–Marche Apennines (Italy, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14841, https://doi.org/10.5194/egusphere-egu26-14841, 2026.
The geometry and evolution of foreland basins in orogenic systems that overprint earlier rifts largely depends on the distribution of rift inheritance. Particularly, the inversion of inherited rift transfer zones drives regional-scale non-cylindrical geometries which impose strong constraints on the 3D distribution of shortening, orogenic topography and syn-orogenic sedimentary depocenters and dispersal patterns. This work addresses the 3D geometrical study of the western part of the Jaca-Pamplona Basin (southern Pyrenees), which represents the early South Pyrenean foreland basin. At its western part, the foreland basin transitions and overlaps the Pamplona transfer zone, a major fringe of oblique structures that resulted from the inversion of a Cretaceous, diffuse rift transfer zone. While basement and cover geometries have been recently revisited in the central and eastern Jaca–Pamplona Basin, the western basin segment remains comparatively underexplored.
To tackle this gap in subsurface characterization, we compiled and interpreted available seismic information. Seismic profiles extend along ~ 3500 km and provide an acceptable 3D coverage of the study area. They are tied by 13 exploration wells, seven of them with associated delta time well log data. The integration of surface geology, seismic surveys and exploration wells has allowed a regional-scale characterization of basement geometries and syn-orogenic depocenters across the study area. Seismic profiles depict a basement that is involved in the deep structure of the western Jaca-Pamplona Basin. Basement units are affected by numerous thrusts that partly result from the reactivation of inherited Permian-Triassic and Early Cretaceous extensional faults. Inverted basement structures are neither cylindrical nor coaxial within the study area, resulting in oblique basement thrust ramps and an along-strike partitioning of outcropping folds and thrusts.
How to cite: Izquierdo Llavall, E., Muñoz, J. A., Santolaria, P., Pueyo, E. L., and Larrasoaña, J. C.: Geometry of a foreland basin over an inherited diffuse rift transfer zone: the western Jaca-Pamplona Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21735, https://doi.org/10.5194/egusphere-egu26-21735, 2026.
During the Miocene formation of the Gibraltar Arc (western Mediterranean), the orogenic load on the SSE margin of the Betics (northern branch) foreland basin led to the formation of an ENE-WSW flexural relief on the foreland (forebulge), producing orthogonal extension accommodated by normal faults oriented parallel to the forebulge strike. However, structural and geomorphic results point to Quaternary relief rejuvenation of the Betics foreland that would account for buckling of the Iberian lithosphere, produced by mechanical coupling and strain transfer from the orogenic wedge to the under-thrusted foreland. This process has been attributed to the Africa-Eurasia convergence and/or to the westward migration of the arc.
In detail, relief rejuvenation of the Betic foreland is mostly accommodated through reactivation of inherited structures, although shows significant differences along strike. In the westernmost sector of the study area, most reactivated structures strike ca. NW-SE to WNW-ESE, which track the Variscan-Paleozoic structural pattern (folds and reverse and left-lateral tanspressional shear zones) of the foreland as well as transfer faults of the Triassic rifting event, and show a main reverse-lateral kinematics. By contrast, in the easternmost sector of the study area, former NE-SW to ENE-WSW extensional faults, likely inherited from the Triassic rifted margin, were reactivated with reverse kinematics.
Other differences between these two sectors are: (1) the eastern sector presents Triassic marly and evaporitic deposits, suggesting a more pronounced extension during the rifting event; (2) the boundary between the foreland basin and the foreland is NE-SW in the eastern sector and ENE-WSW in the western one; (3) the fold-and-thrust in front of the eastern sector defines a rough NE-SW striking secondary arc (the Cazorla arc) with orthogonal convergence kinematics, whereas in front of the western sector, it corresponds to a transitional zone (the Algodonales-Torcal zone) between two secondary arcs and shows dextral transpressional kinematics.
The transitional zone between these two sectors of the foreland shows a hybrid reactivation pattern. The fold-and-thrust in front of this intermediate segment is a ca. E-W striking secondary arc (the Central Betics) with orthogonal convergence kinematics.
The geometrical relationship between the two main sets of inherited structures of the foreland (WNW-ESE and NE-SW to ENE-WSW) and the tentative bulk convergence vector (WNW-ESE) in both sectors is very similar, thus it cannot account for the observed differences between them. Alternatively, in both sectors, the main reactivated structures seem to localize at former extensional faults regardless their age (e.g., the faults controlling the Miocene Bailén and Andújar basins in the eastern sector and the Permian Viar basin and other minor ones of the same age in the western sector). Ongoing research on the architecture of the reactivated faults and numerical modeling will contribute to constrain the main parameters responsible for the observed differences between the two studied sectors of the Betic foreland.
How to cite: Jiménez-Bonilla, A., Díaz-Azpíroz, M., Balanyá, J. C., Alonso, L., Nadal, P., Vázquez, A., Shahsavar, J., and Expósito, I.: Contrasting fault reactivation patterns along the Betic foreland (Gibraltar arc, southern Spain), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19157, https://doi.org/10.5194/egusphere-egu26-19157, 2026.
Much of our current understanding of fold-and-thrust belt (FTB) structure and evolution is based on the critical taper theory. Even though this concept successfully explains the first-order relationship between FTB dynamics and shape via certain physical parameters, it does not account for transient force changes associated with the FTB's internal dynamics, including lateral fault growth or out-of-sequence thrusting. We implement a novel measurement technique to analogue modelling that uses an array of five force sensors aligned at the backstop to characterize the evolution of force. Combined with optical data that monitors surface deformation, this approach provides a methodological framework for capturing second-order force variations associated with non-coaxial deformation within FTBs.
This novel approach enables the prediction of lateral thrust fault growth prior to surface emergence and of out-of-sequence reactivation of earlier-formed thrusts, thereby informing FTB evolution. We examine these relationships by assessing force responses to thrust propagation across pre-existing basement steps, with the ramp angle as the main variable. Our results indicate that a 90° ramp angle generates a pronounced second-order force component, which correlates with enhanced lateral fault variability and associated out-of-sequence thrusting driven by back-thrust activation. A similar structural and force response is observed for a 25° ramp angle, whereas 60° ramp angles produce negligible force disturbances and almost no out-of-sequence thrusting. These results demonstrate the sensitivity of FTB dynamics to structural inheritance.
How to cite: Didden, J., Kosari, E., and Willingshofer, E.: Force changes in response to fault growth and out-of-sequence thrusting in brittle compressional analogue models, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18797, https://doi.org/10.5194/egusphere-egu26-18797, 2026.
It is well documented that many mountain belts - such as the Pyrenees, European Alps, Greater Caucasus, or Atlas - form through inversion of pre-collisional extensional basins. Looking in plan-view at these mountain belts, we observe along-strike variations in topography, orientation, and deformation patterns. However, the relationship between these characteristics and the inherited extensional architecture remains poorly known. Here, we use the 3D thermo-mechanical geodynamic model pTatin3D coupled to the landscape evolution model FastScape to investigate how pre-collisional rift-linkage influences rift inversion and mountain belt evolution. Presenting numerical models and a work minimization analysis, we show that rift basin offset and pre-existing weaknesses determine mountain belt evolution, which can be divided into a juvenile and mature stage. In the juvenile stage, extensional structures are reactivated, creating an orogen that resembles the rift structure. During the mature stage, the evolution depends on the subduction polarity, which is controlled by basin offset and existing structural weaknesses. Same polarity subduction retains the inherited basin configuration and creates an orogen with continuous high topography. Opposite polarity subduction overprints the pre-existing rift configuration and creates a discontinuous mountain belt with a characteristic topographic low in the transition zone. Comparison with the Greater Caucasus, Atlas, and Pyrenees suggests that the Greater Caucasus is a mature same-polarity orogen, the Atlas is a juvenile inversion orogen where subduction polarity plays no significant role, and the Pyrenees are a mature same-polarity orogen in which lateral variabilty is overprinted by differences in the amount of crustal shortening. Based on our results, we propose a simple diagnostic framework that establishes a direct link between topography and deep lithospheric structures, showing how extensional inheritance influences mountain building on Earth.
Associated article:
Wolf, S.G., Huismans, R.S., Muñoz, J.A., May, D.A. (2026) Rift linkage and inheritance determine collisional mountain belt evolution. Nature Communications 17, 84. https://doi.org/10.1038/s41467-025-66695-8
How to cite: Wolf, S. G., Huismans, R. S., Muñoz, J. A., and May, D. A.: The influence of pre-collisional rift linkage on mountain building – a 3D geodynamic modelling study, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10963, https://doi.org/10.5194/egusphere-egu26-10963, 2026.
A significant portion of deformation accommodated during continent–continent collision is localized within mechanically weak domains, particularly those inherited from earlier tectonic phases. While previous studies have highlighted the role of rift-inherited thermal and structural heterogeneities in controlling collision dynamics, the mechanical strength of the continental crust itself is expected to exert a first-order control on crustal accretion, burial, and exhumation processes. In particular, variations in crustal strength may strongly influence the pressure–temperature (P–T) evolution of accreted continental material during collision.
In this study, I investigate the effect of continental crustal strength on the thermo-mechanical evolution of accreted crust using two-dimensional geodynamic numerical modelling. I employ the finite-difference code Norma, using a fully staggered Eulerian grid coupled with a Lagrangian marker field to track material properties and P–T histories. The numerical experiments consist of an initial phase of lithospheric extension, followed by tectonic quiescence and subsequent convergence leading to continental collision. All experiments use an identical rifted margin architecture and thermal setup, while systematically varying the rheological strength of the continental crust.
The parametric study explores a range of crustal strength profiles depending on published crustal flow laws, thereby isolating the mechanical effect of crustal rheology on collision dynamics. The resulting models reveal pronounced differences in deformation style, crustal accretion mechanisms, and P–T paths of accreted crustal slivers. Weaker crust promotes distributed deformation, enhanced crustal thickening, and prolonged residence at mid- to lower-crustal pressures and temperatures, whereas stronger crust favors localized accretion, steeper burial trajectories, and more efficient exhumation along discrete shear zones.
How to cite: Ruh, J. B.: The role of continental crustal strength in controlling deformation and P–T evolution during collision, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3847, https://doi.org/10.5194/egusphere-egu26-3847, 2026.
