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The spatiotemporal interaction of large‐ and regional‐scale upper mantle forces can prevail in collisional settings. To better understand the role of these forces on post‐subduction tectonics, we focus on mantle dynamics in the East Anatolian Plateau, a well‐documented segment of the Arabian‐Eurasian continental collision zone. Specifically, we analyze multiple forces in the upper mantle, which have not been considered in previous studies in this region. To this end, we use a state‐of‐the‐art 3D instantaneous geodynamic model to quantify the dynamics of thermally defined upper mantle structures derived from seismic tomography data. Results reveal a prominent SW‐NE‐oriented mantle flow from the Arabian foreland to the Greater Caucasus–a plumelet–through a lithospheric channel under the East Anatolian Plateau. This plumelet induces localized dynamic topography (∼500 m) around the extensional Lake Van province, favoring NE‐directed compression and westward escape of the Anatolian plate. We suggest that the Lake Van region is an active magma‐rich intraplate rift in the Africa‐Arabia‐Anatolian plume‐rift system. The rift zone was probably initiated by Neotethyan subduction‐related forces and has been reactivated and/or sustained by the plumelet‐induced convective support. Our findings are consistent with numerous observations, including the recent low‐ultralow seismic velocities with a SW‐NE splitting anisotropy pattern, geochemical and petrological studies, and local kinematics showing upper mantle‐induced extensional tectonics in the collisional region. Plain Language Summary: Our goal is to better understand the active deformations of post‐subduction tectonics. To this end, we ran a 3D thermomechanical model of the East Anatolian Plateau, one of the most intriguing segments of the Arabian‐Eurasian continental collision zone. The model integrates seismically defined upper mantle structures and uses an open‐source code (ASPECT). Results reveal the significant role of large‐ and regional‐scale upper mantle forces in the study region. At long wavelengths, we find SW‐NE‐oriented mantle flow and associated dynamic topography. We interpret that such flow—a plumelet (regional upper‐mantle plume migration with neither a significant tail extending to the lower mantle nor a mushroom head reaching the hot spots on the surface)—is linked to the large‐scale mantle flow from the Arabian plate to the Greater Caucasus. At short wavelengths, we find localized dynamic topography and high stress and strain anomalies in the Lake Van zone. We argue that the plumelet, which became more forceful after the removal of the subducted Neotethyan slab, may have generated mantle tractions that contribute to magma‐rich‐intraplate rifting in the Lake Van region. Our results are in good agreement with local kinematics, low‐speed seismic velocities with SW‐NE anisotropy patterns, and geochemical‐petrological studies. Key Points: We present the 3D numerical model and observations related to the Africa‐Arabia‐Anatolian plume‐rift systemOur thermomechanical model provides new insight into the magma‐rich intraplate active rifting in collisional settingsIntegrated analyses from the 3D geodynamic model and observations reveal a SW‐NE‐oriented plumelet and its regional implications [ABSTRACT FROM AUTHOR]

Rifting and continental break-up are major research topics within geosciences, and a thorough understanding of the processes involved as well as of the associated natural hazards and natural resources is of great importance to both science and society. As a result, a large body of knowledge is available in the literature, with most of this previous research being focused on tectonic and geodynamic processes and their links to the evolution of rift systems. We believe that the key task for researchers is to make our knowledge of rift systems available and applicable to face current and future societal challenges. In particular, we should embrace a system analysis approach and aim to apply our knowledge to better understand the links between rift processes, natural hazards, and the geo-resources that are of critical importance to realise the energy transition and a sustainable future. The aim of this paper is therefore to provide a first-order framework for such an approach by providing an up-to-date summary of rifting processes, hazards, and geo-resources, followed by an assessment of future challenges and opportunities for research. We address the varied terminology used to characterise rifting in the scientific literature, followed by a description of rifting processes with a focus on the impact of (1) rheology and stain rates, (2) inheritance in three dimensions, (3) magmatism, and (4) surface processes. Subsequently, we describe the considerable natural hazards that occur in rift settings, which are linked to (1) seismicity, (2) magmatism, and (3) mass wasting, and provide some insights into how the impacts of these hazards can be mitigated. Moreover, we classify and describe the geo-resources occurring in rift environments as (1) non-energy resources, (2) geo-energy resources, (3) water and soils, and (4) opportunities for geological storage. Finally, we discuss the main challenges for the future linked to the aforementioned themes and identify numerous opportunities for follow-up research and knowledge application. In particular, we see great potential in systematic knowledge transfer and collaboration between researchers, industry partners, and government bodies, which may be the key to future successes and advancements. [ABSTRACT FROM AUTHOR]

Central Afar is shaped by the interaction between the Red Sea (RS) and Gulf of Aden (GoA) rifts. While there have been several studies conducted in the region, we know surprisingly little about the mechanism of connection between these two rift branches. Here we use high‐resolution 3D lithospheric scale geodynamic modeling to capture the evolution of linkage between the RS and GoA rifts in central Afar. Our results demonstrate that the two rifts initially overlap and interact across a broad zone of faulting and vertical axis block rotation. However, through time, rift overlap is abandoned in favor of direct linkage which generates a series of localized en‐echelon basins. The present‐day direct linkage between the two rifts is supported by geodetic observations. Our study reconciles previously proposed models for the RS and GoA rift connection by considering spatial and temporal evolution of the rifts. Plain Language Summary: Rifts are places where tectonic plates move away from each other. They normally start as short, isolated features, and then grow and connect together to eventually form oceans. Central Afar in East Africa is a great location to study how these rifts form and grow by connecting with other rifts. In this area, the Red Sea (RS) and Gulf of Aden (GoA) rifts interact, but it is not clear how this happened through time. Some studies suggest that the two rifts form an overlap zone where blocks within the overlap rotate, while others argue that the two rifts directly link and form a continuous rift zone. To resolve this debate, we conducted a high‐resolution computer simulation of the evolution of the RS and GoA rifts in central Afar. We compared our model results with earthquake positions and satellite data that constrain the present‐day motion of the plates. Our results demonstrate that the RS and GoA rifts first overlapped for a few millions of years, and then formed a direct linkage. Our study suggests that both conceptual models can be reconciled when we consider the temporal evolution of the two rifts through geological times. Key Points: Analyzing the spatiotemporal evolution of rifts can address the controversial issue on the connection between propagating riftsWe present results from InSAR and geodynamic models to describe the connection between Red Sea (RS) and Gulf of Aden (GoA) rifts in central AfarThe connection between the two rifts evolves from rift overlap to direct linkage elucidating the observed deformation in the region [ABSTRACT FROM AUTHOR]

Rift propagation is a 3D thermo‐mechanical process that often precedes continental breakup. Pre‐existing microcontinental blocks and the associated lithospheric strength heterogeneities influence the style of rift propagation. Interestingly, some rifts propagate into pre‐existing blocks and eventually cut through them (e.g., the Zhongsha Block and the Reed Bank), while others bypass these microcontinental blocks forming distinct overlapping rift branches (e.g., the East African Rift System). In this study, we use 3D numerical models to investigate the interaction between microcontinental blocks and rift propagation under different far‐field extension rates. In doing so, we assess the impact of mantle lithospheric thicknesses and lower crustal rheology on the style of rift propagation. Our models reproduce the two types of rift propagation, characterized by propagating rifts that either split or bypass the pre‐existing microcontinental blocks. We find that lithospheric thickness exerts dominant control, while lower crustal rheology of microcontinental blocks and the extension rate have less effect on rift propagation. Our model results can explain rift propagation patterns, block rotation and strong lithospheric thinning in the South China Sea, the East African Rift System, and the Woodlark Basin. Plain Language Summary: Rift propagation is an essential process during continental rifting, which rarely follows a straight line due to the heterogeneous nature of continental lithosphere. Here, we use 3D geodynamic numerical modeling to simulate the dynamic evolution of rift propagation interacting with pre‐existing microcontinental blocks. We find that rift propagation is inhibited by strong microcontinental blocks with thick mantle lithosphere, while it splits through weaker microcontinental blocks. We suggest that the strength of microcontinental blocks explains the observed pattern of rift propagation in the South China Sea, the East African Rift System, and the Woodlark Basin. Key Points: Pre‐existing microcontinental blocks affect rift propagationLithospheric heterogeneities play a dominant role in rift propagation patternsModel results elucidate rift propagation patterns in the South China Sea, the East African Rift System, and the Woodlark Basin [ABSTRACT FROM AUTHOR]

Rifting and continental break-up is a key research topic within geosciences, and a thorough understanding of the processes involved, as well as of the associated natural hazard and natural resources is of great importance to both science and society. As a result, a large body of knowledge is available in the literature, yet most of previous research focuses on tectonic and geodynamic processes and their links to the evolution of rift systems. However, we believe that the key challenge for researchers is to make our knowledge of rift systems available and applicable to face new societal challenges. In particular, 5 we should embrace a system analysis approach, and aim to apply our knowledge to better understand the links between rift processes, natural hazards, and the geo-resources that are of critical importance to realize the energy transition and a sustainable future. The aim of this paper is therefore to provide a first-order framework for such an approach, by providing an up-to-date summary of rifting processes, hazards, and geo-resources, followed by an assessment of future challenges and opportunities for research. We address the varied terminology used to characterise rifting in the scientific literature, followed by a description of 10 rifting processes with a focus on the impact of (1) rheology and stain rates, (2) inheritance in three dimensions, (3) magmatism, and (4) surface processes. Subsequently, we address the considerable natural hazards and risks that occur in rift settings, which are linked to (I) seismicity, (II) magmatism, and (III) mass wasting, and provide some insights in how the impacts of these hazards can be mitigated. Moreover, we classify and describe the geo-resources occurring in rift environments as (a) non-energy resources, (b) geo-energy resources, (c) water and soils, and (d) opportunities for geological storage. Finally, we discuss the 15 key challenges for the future linked to the aforementioned themes, and identify numerous opportunities for follow-up research and knowledge application. In particular, we see great potential in systematic knowledge transfer and collaboration between researchers, industry partners and government bodies, which may be the key to future successes and advancements. [ABSTRACT FROM AUTHOR]

Rifting and continental break-up is a key research topic within geosciences, and a thorough understanding of the processes involved, as well as of the associated natural hazard and natural resources is of great importance to both science and society. As a result, a large body of knowledge is available in the literature, yet most of previous research focuses on tectonic and geodynamic processes and their links to the evolution of rift systems. However, we believe that the key challenge for researchers is to make our knowledge of rift systems available and applicable to face new societal challenges. In particular, we should embrace a system analysis approach, and aim to apply our knowledge to better understand the links between rift processes, natural hazards, and the geo-resources that are of critical importance to realize the energy transition and a sustainable future. The aim of this paper is therefore to provide a first-order framework for such an approach, by providing an up-to-date summary of rifting processes, hazards, and geo-resources, followed by an assessment of future challenges and opportunities for research. We address the varied terminology used to characterise rifting in the scientific literature, followed by a description of rifting processes with a focus on the impact of (1) rheology and stain rates, (2) inheritance in three dimensions, (3) magmatism, and (4) surface processes. Subsequently, we address the considerable natural hazards and risks that occur in rift settings, which are linked to (I) seismicity, (II) magmatism, and (III) mass wasting, and provide some insights in how the impacts of these hazards can be mitigated. Moreover, we classify and describe the geo-resources occurring in rift environments as (a) non-energy resources, (b) geo-energy resources, (c) water and soils, and (d) opportunities for geological storage. Finally, we discuss the key challenges for the future linked to the aforementioned themes, and identify numerous opportunities for follow-up research and knowledge application. In particular, we see great potential in systematic knowledge transfer and collaboration between researchers, industry partners and government bodies, which may be the key to future successes and advancements. [ABSTRACT FROM AUTHOR]

To meet the growing global demand for metal resources, new ore deposit discoveries are required. However, finding new, high-grade deposits, particularly those not exposed at the Earth’s surface, is very challenging. Therefore, understanding the geodynamic controls on the mineralizing processes can help identify new areas for exploration. Here we focus on clasticdominated Zn-Pb deposits, the largest global resource of zinc and lead, which formed in sedimentary basins of extensional systems. Using numerical modelling of lithospheric extension coupled with surface erosion and sedimentation, we determine the geodynamic conditions required to generate the rare spatiotemporal window where potential metal source rocks, transport pathways and host sequences are present. We show that the largest potential metal endowment can be expected in narrow asymmetric rifts. This rift type is characterized by rift migration - a process that successively generates hyper-extended crust through sequential faulting, resulting in one wide and one narrow conjugate margin. Rift migration also leads to 1) a sufficient life-span of the migration-side border fault to accommodate a thick submarine package of sediments, including coarse (permeable) continental sediments that can act as source rock; 2) rising asthenosphere beneath the thinned lithosphere/crust resulting in elevated temperatures in these overlying sediments that are favourable to leaching metals from the source rock; 3) the deposition of organic-rich sediments that form the host rock at shallower burial depths and lower temperatures; and 4) the generation of smaller faults that cut the major basin created by the border fault and provide additional fluid pathways from source to host rock. Wide rifts with rift migration can have similarly favourable configurations, but these occur less frequently and less potential source rock is produced, thereby limiting potential metal endowment. In simulations of narrow symmetric rifts, the potential for ore formation mechanisms is low. Based on these insights, exploration programs should prioritize the narrow margins formed in asymmetric rift systems; in particular those regions within several tens of kilometres from the paleoshoreline, where we predict the highest-value deposits to have formed. [ABSTRACT FROM AUTHOR]

To meet the growing global demand for metal resources, new ore deposit discoveries are required. However, finding new, high-grade deposits, particularly those not exposed at the Earth's surface, is very challenging. Therefore, understanding the geodynamic controls on the mineralizing processes can help identify new areas for exploration. Here we focus on clastic-dominated Zn-Pb deposits, the largest global resource of zinc and lead, which formed in sedimentary basins of extensional systems. Using numerical modelling of lithospheric extension coupled with surface erosion and sedimentation, we determine the geodynamic conditions required to generate the rare spatiotemporal window where potential metal source rocks, transport pathways and host sequences are present. We show that the largest potential metal endowment can be expected in narrow asymmetric rifts. This rift type is characterized by rift migration – a process that successively generates hyper-extended crust through sequential faulting, resulting in one wide and one narrow conjugate margin. Rift migration also leads to 1) a sufficient life-span of the migration-side border fault to accommodate a thick submarine package of sediments, including coarse (permeable) continental sediments that can act as source rock; 2) rising asthenosphere beneath the thinned lithosphere/crust resulting in elevated temperatures in these overlying sediments that are favourable to leaching metals from the source rock; 3) the deposition of organic-rich sediments that form the host rock at shallower burial depths and lower temperatures; and 4) the generation of smaller faults that cut the major basin created by the border fault and provide additional fluid pathways from source to host rock. Wide rifts with rift migration can have similarly favourable configurations, but these occur less frequently and less potential source rock is produced, thereby limiting potential metal endowment. In simulations of narrow symmetric rifts, the potential for ore formation mechanisms is low. Based on these insights, exploration programs should prioritize the narrow margins formed in asymmetric rift systems; in particular those regions within several tens of kilometres from the paleo-shoreline, where we predict the highest-value deposits to have formed. [ABSTRACT FROM AUTHOR]

Continental rifts evolve by linkage and interaction of adjacent individual segments. As rift segments propagate, they can cause notable re-orientation of the local stress field so that stress orientations deviate from the regional trend. In return, this stress re-orientation can feed back on progressive deformation and may ultimately deflect propagating rift segments in an unexpected way. Here, we employ numerical and analog experiments of continental rifting to investigate the interaction between stress re-orientation and segment linkage. Both model types employ crustal-scale two-layer setups wherein pre-existing linear heterogeneities are introduced by mechanical weak seeds. We test various seed configurations to investigate the effect of (i) two competing rift segments that propagate unilaterally, (ii) linkage of two opposingly propagating rift segments, and (iii) the combination of these configurations on stress re-orientation and rift linkage. Both the analog and numerical models show counterintuitive rift deflection of two sub-parallel propagating rift segments competing for linkage with an opposingly propagating segment. The deflection pattern can be explained by means of stress analysis in numerical experiments wherein stress re-orientation occurs locally and propagates across the model domain as rift segments propagate. Major stress re-orientations may occur locally, which means that faults and rift segment trends do not necessarily align perpendicularly to far-field extension directions. Our results show that strain localization and stress re-orientation are closely linked, mutually influence each other, and may be an important factor for rift deflection among competing rift segments as observed in nature. [ABSTRACT FROM AUTHOR]

Continental rifts evolve by linkage and interaction of adjacent individual segments. As rift segments propagate, they can cause notable re-orientation of the local stress field so that stress orientations deviate from the regional trend. In return, this stress re-orientation can feed back on progressive deformation and may ultimately deflect propagating rift segments in an unexpected way. Here, we employ numerical and analog experiments of continental rifting to investigate the interaction between stress re-orientation and segment linkage. Both model types employ crustal-scale two-layer setups where pre-existing linear heterogeneities are introduced by mechanical weak seeds. We test various seed configurations to investigate the effect of i) two competing rift segments that propagate unilaterally, ii) linkage of two opposingly propagating rift segments, and iii) the combination of these configurations on stress re orientation and rift linkage. Both the analog and numerical models show counter-intuitive rift deflection of two rift segments competing for linkage with an opposingly propagating segment. The deflection pattern can be explained by means of stress analysis in numerical experiments where stress re-orientation occurs locally and propagates across the model domain as rift segments propagate. Major stress re-orientations may occur locally, which means that faults and rift segment trends do not necessarily align perpendicularly to far-field extension directions. Our results show that strain localization and stress re-orientation are closely linked, mutually influence each other and may be an important factor for rift deflection among competing rift segments as observed in nature. [ABSTRACT FROM AUTHOR]

Assessing the size of a former ocean of which only remnants are found in mountain belts is challenging but crucial to understanding subduction and exhumation processes. Here we present new constraints on the opening and width of the Piemont–Liguria (PL) Ocean, known as the Alpine Tethys together with the Valais Basin. We use a regional tectonic reconstruction of the Western Mediterranean–Alpine area, implemented into a global plate motion model with lithospheric deformation, and 2D thermo-mechanical modeling of the rifting phase to test our kinematic reconstructions for geodynamic consistency. Our model fits well with independent datasets (i.e., ages of syn-rift sediments, rift-related fault activity, and mafic rocks) and shows that, between Europe and northern Adria, the PL Basin opened in four stages: (1) rifting of the proximal continental margin in the Early Jurassic (200–180 Ma), (2) hyper-extension of the distal margin in the Early to Middle Jurassic (180–165 Ma), (3) ocean–continent transition (OCT) formation with mantle exhumation and MORB-type magmatism in the Middle–Late Jurassic (165–154 Ma), and (4) breakup and mature oceanic spreading mostly in the Late Jurassic (154–145 Ma). Spreading was slow to ultra-slow (max. 22 mmyr-1 , full rate) and decreased to ∼5 mmyr-1 after 145 Ma while completely ceasing at about 130 Ma due to the motion of Iberia relative to Europe during the opening of the North Atlantic. The final width of the PL mature ("true") oceanic crust reached a maximum of 250 km along a NW–SE transect between Europe and northwestern Adria. Plate convergence along that same transect has reached 680 km since 84 Ma (420 km between 84–35 Ma, 260 km between 35–0 Ma), which greatly exceeds the width of the ocean. We suggest that at least 63 % of the subducted and accreted material was highly thinned continental lithosphere and most of the Alpine Tethys units exhumed today derived from OCT zones. Our work highlights the significant proportion of distal rifted continental margins involved in subduction and exhumation processes and provides quantitative estimates for future geodynamic modeling and a better understanding of the Alpine Orogeny. [ABSTRACT FROM AUTHOR]

Continental microplates are enigmatic plate boundary features, which can occur in extensional and compressional regimes. Here we focus on microplate formation and their temporal evolution in continental rift settings. To this aim, we employ the geodynamic finite element software ASPECT to conduct 3D lithospheric‐scale numerical models from rift inception to continental breakup. We find that depending on the strike‐perpendicular offset and crustal strength, rift segments connect or interact through one of four regimes: (1) an oblique rift, (2) a transform fault, (3) a rotating continental microplate or (4) a rift jump. We highlight that rotating microplates form at offsets >200 km in weak to moderately strong crustal setups. We describe the dynamics of microplate evolution from initial rift propagation, to segment overlap, vertical‐axis rotation, and eventually continental breakup. These models may explain microplate size and kinematics of the Flemish Cap, the Sao Paulo Plateau, and other continental microplates that formed during continental rifting worldwide. Plain Language Summary: Microplates are enigmatic features that form in the boundaries between tectonic plates. In continental rifts, plates are successively broken to eventually form new oceans. As the continental crust is very heterogeneous, rifts rarely form in straight lines. In some cases, individual rift segments initiate hundreds of kilometers apart both along and perpendicular to strike and as these segments grow, they interact and link. Here we use 3D computer simulations to investigate the linkage of offset rifts. We find that rift linkage is primarily controlled by the strike‐perpendicular offset and crustal strength. At low offset they link through an oblique rift segment, at medium offset a transform fault is formed, and at large offsets in weak crust they overlap and rotate a central block known as a microplate. We suggest that the latter processes have shaped the Flemish Cap, the Sao Paulo Plateau, and many other continental promontories at rifted margins worldwide. Key Points: Strike‐perpendicular offset and crustal strength control the mode of rift segment linkage (microplate, oblique, or transform)Rotating continental microplates form at offsets of >200 km for weak and moderately strong crustModeled microplate evolution may explain the formation of the Flemish Cap, the Sao Paulo Plateau, and other continental promontories [ABSTRACT FROM AUTHOR]

The lithosphere is often assumed to reside in a thermal steady‐state when quantitatively describing the temperature distribution in continental interiors and sedimentary basins, but also at active plate boundaries. Here, we investigate the applicability limit of this assumption at slowly deforming continental rifts. To this aim, we assess the tectonic thermal imprint in numerical experiments that cover a range of realistic rift configurations. For each model scenario, the deviation from thermal equilibrium is evaluated. This is done by comparing the transient temperature field of every model to a corresponding steady‐state model with an identical structural configuration. We find that the validity of the thermal steady‐state assumption strongly depends on rift type, divergence velocity, sampling location, and depth within the rift. Maximum differences between transient and steady‐state models occur in narrow rifts, at the rift sides, and if the extension rate exceeds 0.5–2 mm/a. Wide rifts, however, reside close to thermal steady‐state even for high extension velocities. The transient imprint of rifting appears to be overall negligible for shallow isotherms with a temperature less than 100°C. Contrarily, a steady‐state treatment of deep crustal isotherms leads to an underestimation of crustal temperatures, especially for narrow rift settings. Thus, not only relatively fast rifts like the Gulf of Corinth, Red Sea, and Main Ethiopian Rift, but even slow rifts like the Kenya Rift, Rhine Graben, and Rio Grande Rift must be expected to feature a pronounced transient component in the temperature field and to therefore violate the thermal steady‐state assumption for deeper crustal isotherms. Plain Language Summary: Temperature distribution is a key factor when studying Earth's interior. Here, we quantify the influence of rift velocity on temperature distribution with numerical simulations. As a continent begins to split, forming a rift, hot material beneath the rift center moves upwards increasing the temperatures at shallow crustal depth. However, simple thermal models often assume an equilibrated, constant temperature field. To evaluate tectonically induced changes in temperatures, we compare lithosphere‐scale dynamic models to models with the same material configuration but with a steady‐state temperature distribution and no deformation. We find that the latter approach well represents locations outside the rift valley and shallow crustal depths where comparably low temperatures prevail. Contrarily, at the sides of the rift valley, or for deeper‐lying isotherms like 400°C, the assumption of an equilibrated thermal field leads to an underestimation of crustal temperatures. Furthermore, we show that temperatures in narrow rifts like the Kenya Rift and the Rhine Graben are more strongly modified by tectonic movements than temperatures in wide rifts, like the Basin and Range Province. Finally, we conclude that the assumption of constant temperatures is only valid for wide rifts and very slowly extending narrow rifts with a speed limit of <0.5–2 mm/a. Key Points: We use numerical forward modeling to quantify the transient thermal imprint of continental extensionThe validity of the thermal steady‐state assumption in narrow rifts is limited to extension velocities less than 0.5–2 mm/aTransient thermal effects are particularly significant for deep isotherms, narrow rifts, and beneath the rift shoulders [ABSTRACT FROM AUTHOR]

Assessing the size of a former ocean, of which only remnants are found in mountain belts, is challenging but crucial to understand subduction and exhumation processes. Here we present new constraints on the opening and width of the Piemont-Liguria (PL) Ocean, known as the Alpine Tethys together with the Valais Basin. We use a regional tectonic reconstruction of the Western Mediterranean-Alpine area, implemented into a global plate motion model with lithospheric deformation, and 2D thermo-mechanical modelling of the rifting phase to test our kinematic reconstructions for geodynamic consistency. Our model fits well with independent datasets (i.e. ages of syn-rift sediments, rift-related fault activity and mafic rocks) and shows that the PL Basin opened in four stages: (1) Rifting of the proximal continental margin in Early Jurassic (200-180 Ma), (2) Hyper-extension of the distal margin in Early-Middle Jurassic (180-165 Ma), (3) Ocean-Continent Transition (OCT) formation with mantle exhumation and MORB-type magmatism in Middle-Late Jurassic (165-154 Ma), (4) Break-up and mature oceanic spreading mostly in Late Jurassic (154-145 Ma). Spreading was slow to ultra-slow (max. 22 mm/yr, full rate) and decreased to ~ 5 mm/yr after 145 Ma while completely ceasing at about 130 Ma due to motion of Iberia relative to Europe during the opening of the North Atlantic. The final width of the PL Ocean reached a maximum of 250 km along a NW-SE transect between Europe and Adria (Ivrea). In the Cretaceous and Cenozoic, the amount of plate convergence between Adria (Ivrea) and Europe during Alpine subduction (84-35 Ma, 420 km) and collision (35-0 Ma, 260 km) largely exceeded the width of the ocean. We suggest that at least 63 % of the subducted and accreted material was highly thinned continental lithosphere and most of the Alpine Tethys Ophiolites exhumed today derived from OCT zones. Our work highlights the importance of distal rifted continental margins during subduction and exhumation processes and provides quantitative estimates for future geodynamic modelling and a better understanding of the Alpine Orogeny. [ABSTRACT FROM AUTHOR]

We investigate the thermal and structural evolution of asymmetric rifted margin using numerical modeling and geological observations derived from the Western Pyrenees. Our numerical model provides a self‐consistent physical evolution of the top basement heat flow during asymmetric rifting. The model shows a pronounced thermal asymmetry that is caused by migration of the rift center toward the upper plate. The same process creates a diachronism for the record of maximum heat flow and maximum temperatures (Tmax) in basal rift sequences. The Mauléon‐Arzacq basin (W‐Pyrenees) corresponds to a former mid‐Cretaceous asymmetric hyperextended rift basin. New vitrinite reflectance data in addition to existing data sets from this basin reveal an asymmetry in the distribution of peak heat (Tmax) with respect to the rift shoulders, where highest values are located at the former upper‐ to lower‐plate transition. This data set from the Arzacq‐Mauléon field study confirms for the first time the thermal asymmetry predicted by numerical models. Numerical modeling results also suggest that complexities in synrift thermal architecture could arise when hanging‐wall‐derived extensional allochthons and related Tmax become part of the lower plate and are transported away from the upper‐ to lower‐plate transition. This study emphasizes the limitations of the common approach to integrate punctual thermal data from pre‐rift to synrift sedimentary sequences in order to describe the rift‐related thermal evolution and paleothermal gradients at the scale of a rift basin or a rifted margin. Key Points: Numerical modeling and field observations of asymmetric rifts show an asymmetric thermal evolution during hyperextensionAsymmetric rift basins can record diachronous heat peaks resulting from different successive thermal events (formation of allochthons)Determination of thermal gradients from peak temperatures may be misleading as the thermal architecture results from diachronous evolution [ABSTRACT FROM AUTHOR]

Movements of tectonic plates often induce oblique deformation at divergent plate boundaries. This is in striking contrast with traditional conceptual models of rifting and rifted margin formation, which often assume 2-D deformation where the rift velocity is oriented perpendicular to the plate boundary. Here we quantify the validity of this assumption by analysing the kinematics of major continent-scale rift systems in a global plate tectonic reconstruction from the onset of Pangea breakup until the present day. We evaluate rift obliquity by joint examination of relative extension velocity and local rift trend using the script-based plate reconstruction software pyGPlates. Our results show that the global mean rift obliquity since 230 Ma amounts to 34° with a standard deviation of 24°, using the convention that the angle of obliquity is spanned by extension direction and rift trend normal. We find that more than ~ 70% of all rift segments exceeded an obliquity of 20° demonstrating that oblique rifting should be considered the rule, not the exception. In many cases, rift obliquity and extension velocity increase during rift evolution (e.g. Australia-Antarctica, Gulf of California, South Atlantic, India-Antarctica), which suggests an underlying geodynamic correlation via obliquity-dependent rift strength. Oblique rifting produces 3-D stress and strain fields that cannot be accounted for in simplified 2-D plane strain analysis. We therefore highlight the importance of 3-D approaches in modelling, surveying, and interpretation of most rift segments on Earth where oblique rifting is the dominant mode of deformation. [ABSTRACT FROM AUTHOR]

Crustal rheology controls the style of rifting and ultimately the architecture of rifted margins. Here we review the formation of three magma-poor margin pairs, Iberia-Newfoundland, the central segment of the South Atlantic Rift, and the South China Sea by integrating observational data into a numerical forward modelling framework. We utilise a 2D version of the finite element code SLIM3D, which includes nonlinear temperature- and stress-dependent elasto-visco-plastic rheology and is able to reproduce a wide range of rift-related deformation processes such as flexure, lower crustal flow, and faulting. Extension in cold, strong, or thin crust is accommodated by brittle faults and ductile shear zones that facilitate narrow rifts with asymmetric fault geometries. Hot, weak, or thick continental crust is dominated by ductile deformation and often extends symmetrically into a wide rift system. This simple recipe provides the standard framework to understand initial rift geometry, however, it is insufficient to account for the dynamics of intermediate and late rift stages that shape the final margin architecture. Asymmetric conjugate margins where one side is wide and the other narrow can be formed via both wide and narrow rift styles, which we reproduce with weak and strong crustal rheologies, respectively. Exemplified by the Iberia-Newfoundland conjugates and the Central South Atlantic, we define three characteristic rift phases: an initial phase of simultaneous faulting, an intermediate phase of rift migration that involves sequential fault activity, and finally, the breakup phase. Crustal rheology plays an overarching role in governing the dynamics of these asymmetric margins: we illustrate that weak rheologies generally prolong the phase of simultaneous faulting, while rift migration is enabled by initial fault asymmetry as well as relatively weak crust. Formation of the predominantly symmetric and wide margins of the South China Sea was controlled by extraordinarily weak crust that extended the phase of simultaneous faulting until breakup. The weak crustal rheology of this region relates to the South China Sea's pre-rift history where plate convergence lead to crustal thickening and magmatic additions in a back-arc regime shortly before the onset of rifting. [ABSTRACT FROM AUTHOR]

Abstract: The Gulf of Aden provides an ideal setting to study oblique rifting since numerous structural data are available onshore and offshore. Recent surveys showed that the spatio-temporal evolution of the Gulf of Aden rift system is dominated by three fault orientations: displacement-orthogonal (WSW), rift-parallel (WNW) and an intermediate E–W trend. The oldest parts of the rift that are exposed onshore feature displacement-orthogonal and intermediate directions, whereas the subsequently active necking zone involves mainly rift-parallel faults. The final rift phase recorded at the distal margin is characterised by displacement-orthogonal and intermediate fault orientations. We investigate the evolution of the Gulf of Aden from rift initiation to break-up by means of 3D numerical experiments on lithospheric scale. We apply the finite element model SLIM3D which includes realistic, elasto-visco-plastic rheology and a free surface. Despite recent advances, 3D numerical experiments still require relatively coarse resolution so that individual faults are poorly resolved. We address this issue by proposing a simple post-processing method that uses the surface stress-tensor to evaluate stress regime (extensional, strike-slip, compressional) and preferred fault azimuth. The described method is applicable to any geodynamic model and easy to introduce. Our model reproduces the observed fault pattern of the Gulf of Aden and illustrates how multiple fault directions arise from the interaction of local and far-field tectonic stresses in an evolving rift system. The numerical simulations robustly feature intermediate faults during the initial rift phase, followed by rift-parallel normal faulting at the rift flanks and strike-slip faults in the central part of the rift system. Upon break-up, displacement-orthogonal as well as intermediate faults occur. This study corroborates and extends findings from previous analogue experiments of oblique rifting on lithospheric scale and allows new insights in the timing of fault successions of the Gulf of Aden and continental rifts in general. [Copyright &y& Elsevier]

The article offers information on the numerical modeling of continental and oceanic rifts. Topics discussed include the forces that are involved in rift dynamics including local and far-field forces; the impact of asthenospheric flow on surface stress; and the geodynamics of rift modeling. Also mentioned is a study in the issue focusing on rotational rifting.

Although many collisional orogens form after subduction of oceanic lithosphere between two continents, some orogens result from strain localization within a continent via inversion of structures inherited from continental rifting. Intracontinental rift-inversion orogens exhibit a range of structural styles, but the underlying causes of such variability have not been extensively explored. We use numerical models of intracontinental rift inversion to investigate the impact of parameters including rift structure, rift duration, post-rift cooling, and convergence velocity on orogen structure. Our models reproduce the natural variability of rift-inversion orogens and can be categorized using three endmember styles: asymmetric underthrusting (AU), distributed thickening (DT), and localized polarity flip (PF). Inversion of narrow rifts tends to produce orogens with more localized deformation (styles AU and PF) than those resulting from wide rifts. However, multiple combinations of the parameters we investigated can produce the same structural style. Thus, our models indicate no unique relationship between orogenic structure and the conditions prior to and during inversion. Because the style of rift-inversion orogenesis is highly contingent upon the rift history prior to inversion, knowing the geologic history that preceded rift inversion is essential for translating orogenic structure into the processes that produced that structure. [ABSTRACT FROM AUTHOR]

Oblique divergence at plate boundaries is the kinematic state where the relative plate velocity is not orthogonal to the long-wavelength plate boundary trend. Previous observational and modelling studies suggest that oblique divergence strongly affects syn-rift tectonics, rifted margin formation, as well as the generation of long-offset mid-oceanic transform faults. However, most of these studies focussed on present-day kinematics disregarding past plate boundary configurations. Here we jointly analyse past and present plate kinematics of continental rifts and mid-oceanic ridges worldwide in order to deduce spatiotemporal patterns of oceanic and continental oblique divergence.We find that oblique extension in continental rifts is a very frequent feature. Our analysis shows that more than ~70% of all major continent-scale rift systems since the formation of Pangea exceeded an obliquity of 20° (i.e. the angle between plate boundary trend normal and relative plate divergence velocity). The global mean rift obliquity since 230 Ma amounts to 34° with a standard deviation of 24°. Rifting at these obliquities produces 3-D stress and strain fields that cannot be accounted for in simplified 2-D plane strain analysis. Our results therefore stress the importance of 3-D approaches in modelling, surveying, and interpretation of most rifted margin segments on Earth where oblique rifting was the dominant mode of deformation.Our analysis also shows that at the Atlantic and Indian mid-ocean ridges, the extent of long-offset transform faults (i.e. transforms that exceed 200-300 km length) is primarily controlled by large-scale obliquity while the divergence rate has only secondary importance. In the Pacific Ocean, however, we find the opposite to be true: transform lengths correlate roughly with divergence rate, but not with long-wavelength ridge obliquity. This dichotomy reflects the impact of continental rift obliquity on the Indo-Atlantic ridge network whose overall shape has been inherited from Pangea breakup, whereas the Pacific transforms are entirely unrelated to rifting. We also find that short-offset transform faults with lengths smaller than ~200 km do not exhibit a correlation with divergence obliquity or velocity and thus appear to be entirely controlled by local ridge dynamics. [ABSTRACT FROM AUTHOR]

The São Paulo Plateau is a submarine bathymetric high located in the Santos Basin off the coast of Brazil. Observations from potential field, seismic refraction and -reflection data indicate that the plateau is likely underlain by thinned continental crust. Crustal thickness, sedimentary infill and fault patterns show characteristics of a microplate, which formed in-between the African and South American plates when the Central and Southern rift segments of the South Atlantic emerged with an offset of several hundred kilometers. The underlying reason for the formation and kinematic evolution of the São Paulo Plateau microplate, as well as the amount of rotation and internal deformation, are not well constrained.In this study, we test the effect of crustal strength on microplate formation and evolution in a two-branch rift system. We use the Advanced Solver for Problems in Earth's ConvecTion (ASPECT) code to numerically simulate orthogonal rifting with nonlinear visco-plastic rheology. The setup consists of a 3-D box model with dimensions of 600x500x160 km (X, Y, and Z) that is extended until lithospheric breakup is completed. Extension is prescribed as a constant or time dependent outward velocity at the X-normal boundaries, while the Y-normal boundaries are free-slip, with volumetrically compensating inflow prescribed on the bottom and a free surface at the top. The two rift segments are initialized by 125 km long lithosphere-asthenosphere boundary perturbations of 17 km amplitude at the front and back boundaries that are located 200 km apart in the X-direction. Lithosphere and crustal thicknesses are constant at 120 km and 35 km respectively, and the crustal strength variations are determined by the ratio of the thickness of upper to lower crust. Initial results indicate that a setup with strong crust evolves in two possible ways. In the first case, the fault segments grow until connected by a transform fault. In the second case, one fault stretches across the domain while the other segment dies out. A setup with weaker crust results in an overlap of the segments and a subsequent topographic high forming between them. The rift segments are connected either by a transform fault that forms and transects the topographic high, or by a rotating microplate that eventually connects to one of the plates by a rift jump. In the last case, the model is consistent with observations from the Santos Basin and allows us to constrain the spatiotemporal evolution of the microplate and the dynamics of the eastward rift jump that ultimately transferred the microplate to the South American plate. [ABSTRACT FROM AUTHOR]

Data-driven thermostructural modelling of the lithosphere is a key approach to deduce the subsurface temperature field and rheological state of crust and mantle by integrating gravity, seismic, seismological, and lithological data sets. Such predictive models are mostly based on the assumption that the lithospheric temperature field resides in a thermal steady-state which is well-justified within non-deforming plate interiors. However, the validity of this assumption must be limited when considering active plate boundaries where the temperature field is affected by the advection of heat during lithosphere deformation, a process that we hypothesize to exert more control at higher deformation rates. Here we test this hypothesis by focusing on continental rift dynamics using the finite element geodynamic code ASPECT. In order to account for a range of narrow and wide rift configurations, we model the dynamic rift evolution of setups with 4 crustal thicknesses (20, 30, 40, and 50 km), each of them extended at 11 different rift velocities (0.5-10 mm/yr). Our model setups account for four layers (sublithospheric mantle, lithospheric mantle, lower crust, upper crust) that deform in a visco-plastic manner. After a total extension of 50 km and 100 km, we extract the current lithospheric configuration and compute the purely conductive thermal steady-state. These steady-state subsurface temperatures are calculated based on individual layer thicknesses and their thermal properties, while thermal inheritance from the rifting process is neglected. By comparing key observables of these steady-state snapshots (i.e. the depth of the 100, 200, 300, and 400°C isotherms and the depth of the deepest brittle-ductile-transition) to those of the transient thermomechanical models, we finally assess the suitability of steady-state modelling approaches in continental rift settings.We find that wide rifts, where local advection rates are much slower than in narrow rifts, reside in a thermal steady-state for all tested rift velocities. In narrow rift configurations, however, our hypothesis of a speed limit for the thermal steady-state assumption can be clearly verified for all observables. Assuming vertical uncertainties of +/- 5 km for all our observables (isotherms and brittle-ductile transition), we deduce that at a total extension of 50 km the steady-state approach in narrow rift settings is suitable for extension velocities smaller than ~2-3 mm/yr. At 100 km of extension, the rift velocity can be as fast as ~2-5 mm/yr depending on the observable and crustal thickness. We conclude that slow rifts like the Kenya Rift, Rhine Graben, and Rio Grande Rift as well as wide rifts like the Basin and Range Province lie within the steady-state limits. Contrastingly, narrow and relatively fast rifts like the Afar rift segments, the Red Sea, and the Gulf of Corinth must be expected to feature a pronounced transient component in the temperature field and therefore to violate the thermal steady-state assumption. [ABSTRACT FROM AUTHOR]

Abstract The extent of continental rifts and subduction zones through deep geological time provides insights into the mechanisms behind supercontinent cycles and the long term evolution of the mantle. However, previous compilations have stopped short of mapping the locations of rifts and subduction zones continuously since the Neoproterozoic and within a self-consistent plate kinematic framework. Using recently published plate models with continuously closing boundaries for the Neoproterozoic and Phanerozoic, we estimate how rift and peri-continental subduction length vary from 1 Ga to present and test hypotheses pertaining to the supercontinent cycle and supercontinent breakup. We extract measures of continental perimeter-to-area ratio as a proxy for the existence of a supercontinent, where during times of supercontinent existence the perimeter-to-area ratio should be low, and during assembly and dispersal it should be high. The amalgamation of Gondwana is clearly represented by changes in the length of peri-continental subduction and the breakup of Rodinia and Pangea by changes in rift lengths. The assembly of Pangea is not clearly defined using plate boundary lengths, likely because its formation resulted from the collision of only two large continents. Instead the assembly of Gondwana (ca. 520 Ma) marks the most prominent change in arc length and perimeter-to-area ratio during the last billion years suggesting that Gondwana during the Early Palaeozoic could explicitly be considered part of a Phanerozoic supercontinent. Consequently, the traditional understanding of the supercontinent cycle, in terms of supercontinent existence for short periods of time before dispersal and re-accretion, may be inadequate to fully describe the cycle. Instead, either a two-stage supercontinent cycle could be a more appropriate concept, or alternatively the time period of 1 to 0 Ga has to be considered as being dominated by supercontinent existence, with brief periods of dispersal and amalgamation. Highlights • Compilation of rifting events in the Neoproterozoic • Analysis of continental arc, continental rift and connectedness of continental lithosphere for the last 1 Ga • Two stage supercontinent cycle may better explain changes in the connectedness of continental lithosphere • Extraversion and introversion models of successive supercontinents occur on different timescales [ABSTRACT FROM AUTHOR]

The relationships between volcanic activity and tectonics at the southernmost termination of the Main Ethiopian Rift (MER), East Africa, still represent a debated problem in the MER evolution. New constraints on the timing, evolution and characteristics of the poorly documented volcanic activity of the Dilo and Mega volcanic fields (VF), near the Kenya-Ethiopia border are here presented and discussed. The new data delineate the occurrence of two distinct groups of volcanic rocks: 1) Pliocene subalkaline basalts, observed only in the Dilo VF, forming a lava basement faulted during a significant rifting phase; 2) Quaternary alkaline basalts, occurring in the two volcanic fields as pyroclastic products and lava flows issued from monogenetic edifices and covering the rift-related faults. 40Ar/39Ar dating constrains the emplacement time of the large basal lava plateau to ~3.7 Ma, whereas the youngest volcanic activity characterising the two areas dates back to 134 ka (Dilo VF) to as recent as the Holocene (Mega VF). Volcanic activity developed along tectonic lineaments independent from those of the rift. No direct relations are observed between the Pliocene, roughly N-S-trending major boundary faults of the Ririba rift and the NE-SW-oriented structural trend characteristic of the Quaternary volcanic activity. We speculate that this change in structural trend may be the expression of (1) inherited crustal structures affecting the distribution of the recent volcanic vents, and (2) a local stress field controlled by differences in crustal thickness, following a major episode of reorganization of extensional structures in the region due to rift propagation and abandonment. • Multidisciplinary study of the Dilo and Mega volcanic fields in South Ethiopia • Two phases of volcanism: Pliocene tholeiitic basalts and Quaternary alkaline basalts • Quaternary volcanism is unrelated to rifting and rift-related structures. • Inherited fabrics and local stress field influence volcanism after rift abandonment. [ABSTRACT FROM AUTHOR]

The conjugate Santos/Campos-Namibe/Benguela margin system of the South Atlantic is the result of complex 3D interaction of two rift segments. Data acquired in the context of extensive hydrocarbon exploration efforts in the basins allow to study the first order evolution of lithosphere deformation, magmatism, microplate and basin infill dynamics across scales in an area of interacting rift segments. Utilising an extensive set of industry seismic, well and potential field data we can subdivide the evolution of the rift system into three key phases, linked to changes in the plate kinematics.The South Atlantic rift was initiated in earliest Cretaceous time, prior to the arrival of the Tristan plume. During this first phase, deformation primarily localised in the western, proximal part of the Santos basin. In this early rift phase, the arrival of the Tristan plume resulted in the emplacement of the Parana-Etendeka large igneous province, significantly affecting the evolving rift architecture and infill, and leading to a phase of potentially magma-compensated thinning with extensive subaerial volcanism. Fault mapping and -activity age assignment based on seismic stratigraphy indicates continued eastward migration of deformation towards the Base Salt deposition time, documented by an extensive set of westward dipping normal faults. At around 125 Ma, changes in extension direction and velocities can be linked to an eastward jump of the deformation towards the African margin resulting in a second, transitional, phase and likely the formation of the so-called Jupiter step. During deposition of salt, rift segment linkage and structural re-organisation continued in the Jupiter step area with significantly less magmatism than observed in the earlier extension phase and a predominantely eastward-dipping structural grain. Subsequent hyperextension and highly asymmetric thinning in the last phase lead to a conjugate rifted margin system with a wide Santos and narrow Namibe margin before establishment of a seafloor spreading ridge between Africa and South America.We supplement our observation-driven synthesis by means of 3D forward numerical modelling of lithosphere deformation using the code ASPECT. Exploiting a range of permissible geometrical and kinematic boundary conditions, we investigate 3D rift evolution scenarios, which address the effect of rift segment overlap and -orientation on microplate- and accommodation space formation. [ABSTRACT FROM AUTHOR]

Continental rift systems commonly form by progressive growth of isolated rift segments that interact and link, eventually evolving into continuous zones of deformation. Propagation and interaction between adjacent rift segments are important features of rifting, influencing the distribution of volcanoes, seismicity and sedimentary basins. The process also controls the morphology of the rift at breakup with possible implications for the segmentation of mid-ocean ridges. However, how the punctuated, discontinuous zones of extension propagate and interact to form a continuous rift system and how the complex zones of interaction evolve remain poorly documented and understood. The Turkana depression in East Africa is an ideal place where to analyse these processes: within this NW-SE lowland, two major sectors of the East African rift, the Kenyan and Ethiopian rifts, interact giving rise a complex, >300km-wide region of faulting and volcanic activity.In this work, we present geological-structural, geochemical and geochronological data from the poorly documented Ririba rift (South Ethiopia), which is part of the complex, wide region of volcano-tectonic activity in the Turkana depression. This rift is of special interest because it is commonly accepted to represent the southernmost, youngest and less-developed sector of the Ethiopian Rift, having formed from recent southward propagation of this rift into the Turkana depression. Our data confirm the Ririba rift formed from the southward propagation of the Ethiopian rift during the Pliocene but this propagation was short-lived and aborted close to the Pliocene-Pleistocene boundary, when rift-related deformation ceased. Integration of seismicity data with new numerical models indicates that abandonment of laterally offset and overlapping tips of the Ethiopian and Kenyan rifts resulted from progressive focusing of the tectonic and magmatic activity into an oblique, throughgoing rift zone which directly connects the rift sectors. These sectors link by near pure extension without forming the strike-slip transfer faults interpreted as precursors of oceanic transform faults [ABSTRACT FROM AUTHOR]