Russell N. Pysklywec’s research while affiliated with University of Toronto and other places

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Publications (150)


Application of Generative Adversarial Networks in Geoelectrical Field Data Interpretation
  • Preprint
  • File available

November 2024

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19 Reads

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O. M. Alile

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R. N. Pysklywec

The geoelectrical survey method generates subsurface cross-sections images based on physical properties, but requires solution of an inverse problem with potential ambiguities in model interpretation and substructure uncertainties. The integration of electrical resistivity tomography (ERT) and machine learning computational approaches is adopted in this study to reduce these ambiguities and uncertainties as well as the labour-intensive nature of the standard computational approach. A data set collected from landfill locations in Nigeria is inverted by the conventional geophysical method of interpretation using the RES2DINV software. The inverted data (true resistivity tomography images) along with the source data (apparent resistivity images) are used as training samples to develop predictor models based on the Pix2Pix conditional generative adversarial networks (Pix2Pix-cGAN). Initial results with a small number of training samples reveal about 89% structural similarity between the true resistivity topography obtained by the standard inversion method and those predicted by the Pix2Pix translator. Our novel approach can be applied to the analysis of seismic data from the lithosphere and mantle.

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Geological and tectonic setting of study area
a Tectonic regions and plate motions of Anatolia. Purple arrows indicate relative plate motions with respect to Eurasia (numbers show the average velocities in mm/yr)80–83. b Shaded relief topographic map of Central Anatolia including volcanic provinces (Galatia and Cappadocia Volcanic Provinces shaded in red). The blue dashed line outlines the boundaries of the Konya Basin and a shaded area indicates paleolake Konya. White lines show main active faults in Anatolia with yellow arrows indicating the sense of shear11,21. The figure was created by the Generic Mapping Tools GMT 6⁸⁴. c GNSS and INSAR based vertical velocities (Vup) in mm/yr in the Konya Basin showing rapid subsidence of the basin up to rates of >50 mm/yr²⁴.
Geophysical anomalies of Central Anatolia
a S-wave seismic tomography along the N-S transect (a’-a) showing a fast seismic wave speed anomaly beneath the Konya Basin indicated by a white arrow, and another anomaly beneath the Kırşehir Arc to the north²⁷. The white dashed line approximately delineates the lithosphere-asthenosphere-boundary (LAB). b Crustal thickness variations derived from Vanacore et al.³². c Our calculation of residual (non isostatic) topography showing negative residuals in the Konya Basin. d For comparison, we show residual topography estimates from Howell et al. ³⁴. e Surface topographic map of Central Anatolia⁷⁹.
Results of laboratory (analogue) experiments
a Sideview image of the primary drip at 10 h. The drip has begun descending through the tank and is characterised by a bulbous drip head. b Sideview image of the primary drip at 25 h. The drip has almost touched the bottom of the box. The neck of the drip is thin (~1/4 the width of the drip head). Green vectors show increased downward velocity of the drip. c Digital image of the model top surface at 25 h. The rectangular box outlines a 3 × 5 cm surface area above the drip on the model surface. The image shows the unperturbed upper crust layer indicating that there is no horizontal crustal tectonic deformation—such as shortening or extension--reaching the surface despite the underlying drip behaviour. d Sideview image of the experiment at 50.6 h. There is a growth of a secondary drip, ~2 cm below the base of the lithosphere. e Surface elevation contour map directly above the secondary drip at 50.6 h. A basin is visible in the surface that scales to 1.25 km deep. f Sideview image of drip progression 6.5 h later (57.1 h since the start) in the experiment. Now the secondary drip pulse has travelled ~3 cm beneath the lithosphere (green vectors). g Surface elevation contour map directly above the secondary drip at 57.1 h. The basin has deepened to 1.5 km. h A digital image of the model surface at 57.1 h. The sand crust layer does not show horizontal deformation at the surface while the lithosphere drips underneath (i.e., this is an asympomatic drip; Suppl. Fig. 2). i Vertical displacement of the model surface between 50.6 h and 57.1 h. The negative displacement in the dashed rectangular boundaries corresponds to a subsidence of the basin formed by the secondary drip.
The evolution of multiple stage lithospheric dripping process in Central Anatolia
a Lithospheric removal via a primary drip beneath Central Anatolia causing plateau uplift since ~10–8 Ma, subsequent to the shortening and thickening of the Kırşehır arc. b The development of a secondary drip and associated Konya basin formation. c Timeline of lithospheric drip and topographic evolution of Central Anatolia from 25 Ma to present.
Rheology, density, and thickness of analogue materials with scaling factor (SF)
Multistage lithospheric drips control active basin formation within an uplifting orogenic plateau

September 2024

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555 Reads

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1 Citation

According to GNSS/INSAR measurements, the Konya Basin in Central Anatolia is undergoing rapid subsidence within an uplifting orogenic plateau. Further, geophysical studies reveal thickened crust under the basin and a fast seismic wave speed anomaly in the underlying mantle, in addition to a localised depression in calculated residual topography (down to 280 m) over the Konya Basin, based on gravity-topography considerations. Using scaled laboratory (analogue) experiments we show that the active formation of the Konya Basin may be accounted for by the descent of a mantle lithospheric drip causing local circular-shaped surface subsidence. We interpret that the Konya Basin is developing through a secondary drip pulse that is contemporaneous with broad plateau uplift caused by a larger-scale lithospheric drip since the Miocene. The research reveals that basin evolution and plateau uplift may be linked in a multistage process of lithospheric removal during episodic development of orogenic systems.


The Role of Upper Mantle Forces in Post‐Subduction Tectonics: Plumelet and Active Rifting in the East Anatolian Plateau

September 2024

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436 Reads

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1 Citation

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.



Major oceanic plateaux and subduction zones in the western Pacific. The map shows locations of the Ontong Java, Shatsky, Hess, and Manihiki plateaux and their significant extensional features that are parallel or sub‐parallel to the subduction trenches (see references in the text). The base map was made with GeoMapApp (www.geomapapp.org) under a Creative Commons license CC BY 4.0.
Extensional tectonics in seismic reflection profiles. (a, b, c, and d) Bathymetric maps of the OJP, SR, HR, and MP and locations of the marine seismic reflection profiles including major extensional structures (Phinney et al., 1999; Pietsch & Uenzelmann‐Neben, 2016; Zhang et al., 2015). (e and f) Seismic reflection profiles (a–a´) from the OJP (Phinney et al., 1999). OJ1, OJ2, and OJ3 represent early Cretaceous basement, Cretaceous mudstone and carbonates, late Cretaceous through pelagic carbonate, respectively (Phinney et al., 1999). (g and h) Seismic reflection profiles (b–b´ and c–c´) from the SR. Large normal faults are located mainly on the trench/western side of the SR and cut young sediment layers (Sager et al., 2013; Zhang et al., 2015). (i) Seismic reflection profile (d–d´) from the HR. Wide grabens and normal faults started to form at 82 Ma and are most probably still active since the young strata is displaced by the extensional structures (Vallier et al., 1981, 1983). (j and k) Seismic reflection profile (e–e´) from the MP. The cross section cuts the Suvarov Trough, grabens, and normal faults (Pietsch & Uenzelmann‐Neben, 2016).
Syn‐drift extension mechanism and experiment results. (a) Snapshot frames of EXP‐1 from the experiment start to end. Frames are aligned along the plateau end to illustrate the progressive syn‐drift extension through the model evolution. See text for detailed explanation. (b) A comparison of stretching factor (β = current crustal thickness/initial thickness) calculations from the front and back regions of the oceanic plateau crust during the EXP‐1 development. (c) The subduction pulley analogy that explains the syn‐drift ocean plateau extension tectonics (Gün et al., 2021). (d) Stretching factor (current ocean plateau width/initial width) evolution plots of EXP‐1 to 4. Experiments show a similar plateau extension development regardless of the initial distance from trench. See text for details.
Syn‐Drift Plate Tectonics

January 2024

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726 Reads

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2 Citations

The paradigm of plate tectonics holds that ocean plates are rigid during drift and only experience tectonic deformation at subduction zones, but new findings from the Pacific challenge this idea. Geological and geophysical evidence from the Ontong Java, Shatsky, Hess, and Manihiki oceanic plateaux indicates that extensional deformation during plate drift is a widespread phenomenon across the Pacific plate. These anomalously thick oceanic plateaux are weaker regions of the ocean lithosphere and more prone to tectonic deformation. Numerical geodynamic models demonstrate that a slab pull force from distant subduction plate boundaries can be effectively transmitted to oceanic plateaux through strong ocean lithosphere and cause substantial extension during plate drift. Our findings reveal that a wide expanse of the Pacific has experienced syn‐drift plate tectonics linked to pull from the western Pacific subduction factory.


Transient Injection of Flow: How Torn and Bent Slabs Induce Unusual Mantle Circulation Patterns Near a Flat Slab

September 2023

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429 Reads

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4 Citations

Torn and bent slabs are usually associated with flat‐slab subduction where the descending plate develops a horizontal geometry beneath the overlying continent. How such slab dynamics modify the surrounding mantle flow and the overriding plate remains enigmatic. Here, we conduct three‐dimensional subduction numerical experiments to investigate the flat slab to steep‐angle slab transition region and examine the impact of slab geometry changes on mantle flows. The results show that the along‐strike change due to flattening a segment of slab induces oblique flow toward the mantle corner at the transition region where flat slab bends to steep‐subducting slab. Slab tears can occur due to the buoyancy contrast between an oceanic ridge and the surrounding dense oceanic crust and/or presence of weak zones. A vertical tear at the side edge of a flat slab causes toroidal flow around the steep‐angle slab where sub‐slab mantle floods rapidly through the tear. Flow through the tear spreads to all directions including upwelling toward the continental base that may trigger slab and partial melting and thus affect arc magmatism. A horizontal tear that occurs ahead of the flat portion where slab resumes its steep‐angle results in enhanced plate‐motion parallel flow. Notably, the tear‐induced flow behaves as a rapid injection through the slab breach with the peak velocity up to an order of magnitude higher than plate motion, lasting for 1–2 million years after initially tearing. This rapid pulse flow might be recorded in surface tectonics as distinct transient events of topography or metamorphism.


The role of subduction in the formation of Pangean oceanic large igneous provinces

June 2023

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196 Reads

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4 Citations

Geological Society London Special Publications

Large igneous provinces (LIPs) have been linked to both surface and deep mantle processes. During the formation, tenure, and breakup of the supercontinent Pangea, there is an increase in emplacement events for both continental and oceanic LIPs. There is currently no clear consensus on the origin of LIPs, but a hypothesis relates their formation to crustal emplacement of hot plume material originating in the deep mantle. The interaction of subducted slabs with the lowermost mantle thermal boundary and subsequent return-flow is a key control on such plume generation. This mechanism has been explored for LIPs below the interior of a supercontinent (i.e., continental LIPs). However, a number of LIPs formed exterior to Pangea (e.g., Ontong Java Plateau), with no consensus on their formation mechanism. Here, we consider the dynamics of supercontinent processes as predicted by numerical models of mantle convection, and analyse whether circum-supercontinent subduction could generate both interior (continental) and exterior (oceanic) deep-mantle plumes. Our numerical models show that subduction related to the supercontinent cycle can reproduce the location and timing of the Ontong Java Plateau, Caribbean LIP, and potentially the Shatsky Rise, by linking the origin of these LIPs to the return-flow that generated deep mantle exterior plumes.


Fig. 2 | Geophysical anomalies of Central Anatolia. a S-wave seismic tomography along the N-S transect (a'-a) showing a fast seismic wave speed anomaly beneath the Konya Basin indicated by a white arrow, and another anomaly beneath the Kırşehir Arc to the north 27 . The white dashed line approximately delineates the lithosphereasthenosphere-boundary (LAB). b Crustal thickness variations derived from Vanacore et al. 32 . c Our calculation of residual (non isostatic) topography showing negative residuals in the Konya Basin. d For comparison, we show residual topography estimates from Howell et al. 34 . e Surface topographic map of Central Anatolia 79 .
Fig. 3 | Results of laboratory (analogue) experiments. a Sideview image of the primary drip at 10 h. The drip has begun descending through the tank and is characterised by a bulbous drip head. b Sideview image of the primary drip at 25 h. The drip has almost touched the bottom of the box. The neck of the drip is thin (~1/4 the width of the drip head). Green vectors show increased downward velocity of the drip. c Digital image of the model top surface at 25 h. The rectangular box outlines a 3 × 5 cm surface area above the drip on the model surface. The image shows the unperturbed upper crust layer indicating that there is no horizontal crustal tectonic deformation-such as shortening or extension--reaching the surface despite the underlying drip behaviour. d Sideview image of the experiment at 50.6 h. There is a growth of a secondary drip, ~2 cm below the base of the lithosphere. e Surface
Fig. 4 | The evolution of multiple stage lithospheric dripping process in Central Anatolia. a Lithospheric removal via a primary drip beneath Central Anatolia causing plateau uplift since ~10-8 Ma, subsequent to the shortening and thickening of the Kırşehır arc. b The development of a secondary drip and associated Konya basin formation. c Timeline of lithospheric drip and topographic evolution of Central Anatolia from 25 Ma to present.
Rheology, density, and thickness of analogue materials with scaling factor (SF)
Asymptomatic lithospheric drip driving subsidence of Konya Basin, Central Anatolia

Geological and geophysical observations show instances of surface subsidence, uplift, shortening, and missing mantle lithosphere inferred as manifestations of the large-scale removal of the lower lithosphere. This process—specifically by viscous instability or lithospheric “drips” —is thought to be responsible for the removal or thinning of the lithosphere in plate hinterland settings such as: Anatolia, Tibet, Colorado Plateau and the Andes. In this study, we conduct a series of scaled, 3D analogue/laboratory experiments of modeled lithospheric instability with quantitative analyses using the high-resolution Particle Image Velocimetry (PIV) and digital photogrammetry techniques. Experimental outcomes reveal that a lithospheric drip may be either ‘symptomatic’ or ‘asymptomatic’ depending on the magnitude and style of recorded surface strain. Notably, this is controlled by the degree of coupling between the downwelling lithosphere and the overlying upper mantle lithosphere. A symptomatic drip will produce subsidence followed by uplift and thickening/shortening creating distinct ‘wrinkle-like’ structures in the upper crust. However, the ‘symptoms’ of an asymptomatic drip are subdued as it only yields subsidence or uplift, with no evidence of shortening in the upper crust. Here, we combine analogue modelling results with geological and geophysical data to demonstrate that the Konya Basin in Central Anatolia (Turkey) is one such example of an asymptomatic drip. Global Navigation Satellite System (GNSS) measurements reveal elevated vertical subsidence rates (up to 50 mm/yr) but no well-documented crustal strain or structural features such as fold-and-thrust belts. This work demonstrates that different types of lithospheric drips may exist since the Archean, and there may be instances where the mantle lithosphere is dripping with no distinct manifestations of such a process in the upper crust.


The coherence function and lithospheric elastic thickness of the Zagros fold and thrust belt

April 2023

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100 Reads

Geophysical Journal International

This study derives the spatial variation of the elastic thickness (Te) and its implications for understanding the structure, geodynamic, and seismicity of the lithosphere for the Zagros fold and thrust belt region of the Arabia-Eurasia collision zone. Te is calculated using the coherence function in the fan wavelet domain based on recent terrestrial Bouguer gravity and topography data as input signals. Utilizing the load deconvolution method and Brent's method of 1D minimization, the final Te for the survey region is estimated for each grid node of the studied area. To illustrate the mass distribution in the studied area, the subsurface loading fraction (F) is calculated simultaneously with Te in the inversion. The crust thickness and density from three different global crustal models are tested and the results obtained for these input models do not yield substantially different Te patterns. The final results are in accord with the global Te models as well as previous rheological, geodynamical, and flexural studies, however, this study establishes much more detailed regional information. The calculations yield a mean value of Te of 61 km for the Zagros, with a mean estimated error of about 5 km. The high-Te values (>70 km) are observed in the southeast of the studied area (some parts of the Sanandaj-Sirjan zone, Urumieh-Dokhtar magmatic arc and most of the Central Iranian blocks); while over most of the northwest of the studied area, the value of Te is about 58 km. The Te results are consistent with the lithospheric structure of the study area and also support the idea of the crust-mantle decoupling. Further, there is a positive and negative correlation between the surface wave velocity and surface heat flow, respectively. The mean value estimated for the internal loading friction (F) of 0.4 means in most of the studied areas we may consider that the surface loading is dominant, or at least the ratio of the surface and subsurface loading can be assumed equal. Based on earthquake distribution in the period 1900–2020, seismicity is more likely to occur in areas with a relatively low value of Te.


Citations (47)


... Whether the loss takes the shape of a drip or delamination (Beall et al., 2017;Göǧüş & Pysklywec, 2008) can not be resolved with our observations since both cases would be expected to generate the shear layer (Göǧüş & Pysklywec, 2008). Lithospheric loss that is in some cases sequential has been proposed for other regions such as the Anatolian Plateau (Andersen et al., 2024;Göğüş et al., 2017), New Zealand (Dimech et al., 2017), and the Carpathians (Lorinczi & Houseman, 2009). ...

Reference:

Lithospheric Foundering in Progress Imaged Under an Extinct Continental Arc
Multistage lithospheric drips control active basin formation within an uplifting orogenic plateau

... Active normal faults are often observed on many oceanic plateaus (Gün et al., 2024); however, whether subduction still induces substantial flexural deformation and faulting in thickened oceanic lithosphere is not well understood. In normal oceanic lithosphere, outer-rise flexural extension can alter the composition and porosity of the subducting plate through fracturing and chemical hydration reactions (Ranero et al., 2003;Van Avendonk et al., 2011;Naif et al., 2015;Grevemeyer et al., 2018;Miller et al., 2021;Acquisto et al., 2022). ...

Syn‐Drift Plate Tectonics

... Right below the overriding plate, small-scale convection cells that oppose the corner flow can form where the slab decouples from the overriding plate 77 . Numerical models have shown that during formation of a flat-slab segment, a local toroidal-like return flow moves mantle material from the forefront of the flat-slab region to the wedge area of the neighbouring steep slab segment 78 . Local mantle upwelling might also occur adjacent to the flat region of the slab and close to the trench. ...

Transient Injection of Flow: How Torn and Bent Slabs Induce Unusual Mantle Circulation Patterns Near a Flat Slab

... Instead, they argue that the lack of evidence for crustal thickening or change in lower-crustal sources and melting conditions is incompatible with Baltica's amalgamation into Rodinia, and that Baltica may have been isolated until the Silurian Caledonian orogeny. Heron et al. (2023) explore the role of subduction in the formation of oceanic large igneous provinces (LIPs) exterior to Pangaea. Using numerical models of mantle convection, they examine whether circum-supercontinent subduction could generate oceanic deep-mantle plumes exterior to Pangaea in addition to generating the more familiar continental plumes below the interior of the supercontinent. ...

The role of subduction in the formation of Pangean oceanic large igneous provinces
  • Citing Article
  • June 2023

Geological Society London Special Publications

... Previous studies (Holdsworth et al., 2001;Thomas, 2006) suggest that preexisting structures and fabrics play a significant role in accommodating extension at continental margins due to fracturing and faulting in the brittle upper crust. Whereas more recent scaled numerical models (Heron et al., 2023;Peace, Dempsey, et al., 2018) emphasize the dominant influence of mechanical heterogeneities within the mantle lithosphere in guiding surface tectonic deformation. Although numerical simulations and finite element analysis provide analytical solutions to elucidate tectonic processes that cannot be directly observed, they are constrained by governing equations and computing power and therefore may limit the extent to which they reproduce actual geological observations. ...

Stranding continental crustal fragments during continent breakup: Mantle suture reactivation in the Nain Province of Eastern Canada

Geology

... An analogue model is a simplified, 3D model created in the laboratory using selected materials as scaled analogues for the Earth's sublithospheric mantle, mantle lithosphere (upper mantle) and the upper crust. The analogue model in this study was constructed using methods from 58,59 . The sub-lithospheric mantle in the model was a viscous silicone polymer -polydimethylsiloxane (PDMS). ...

Symptomatic lithospheric drips triggering fast topographic rise and crustal deformation in the Central Andes

... Mantle convective support of topography can be analyzed from elastically uncompensated long-wavelength gravity anomalies [33][34][35][36] . Based on the relationship between gravity and topography, it is generally suggested that the ratio associated with convective support at long-wavelengths (≥~300km) is 50mGal/km for continents and 30 mGal/km for ocean bathymetry (Howell et al., 34 and references therein). ...

Geodynamics of East Anatolia‐Caucasus Domain: Inferences From 3D Thermo‐Mechanical Models, Residual Topography, and Admittance Function Analyses

... Previous works have analyzed the impact of various parameters on the evolution of subduction systems characterized by oceanic plateaus, seamounts, or microcontinents (e.g., De Franco et al., 2008a;Gerya et al., 2009;Gün et al., 2022;Tao et al., 2020;Tetreault & Buiter, 2012;Vogt & Gerya, 2014;Z. Yan et al., 2022;Yang et al., 2018). ...

Terrane geodynamics: Evolution on the subduction conveyor from pre-collision to post-collision and implications on Tethyan orogeny

Gondwana Research

... Since the first discovery of "super-Earths" (Rivera et al. 2005), a growing effort has been devoted to the studies in the internal (radial) structure (e.g., Seager et al. 2007;Sotin et al. 2007;Wagner et al. 2011), the thermal evolution (e.g., Papuc and Davies 2008;Kite et al. 2009;Korenaga 2010;Gaidos et al. 2010;Tachinami et al. 2011;Čížková et al. 2017) and the habitability (e.g., Noack et al. 2017;Tosi et al. 2017;Foley 2019) of such massive terrestrial bodies. During the last decades, the studies on mantle dynamics have been playing an important role in addressing these issues (e.g., Kameyama and Yamamoto 2018;Berg et al. 2019;Shahnas and Pysklywec 2021;Kameyama 2022;Ricard and Alboussière 2023). ...

Focused Penetrative Plumes: A Possible Consequence of the Dissociation Transition of Post‐Perovskite at ∼0.9 TPa in Massive Rocky Super‐Earths

... Subsequently, to examine the effects of convergence velocity (u c ), we perform several experiments with values that are lower than in the reference experiment (4.5 cm yr 1 ): 3.0, 1.5, and 0.5 cm yr 1 (models 8-10). It is well known that in natural collisional settings, the presence of a small continental block (microcontinent) extending along the passive margin can add complexity not only to the architecture of the original passive margin but also to the resulting collisional orogen (Eskens et al., 2024), potentially affecting the processes of slab breakoff and tear propagation (Gün et al., 2021;Handy et al., 2010). We therefore complete our modeling set with experiments containing a microcontinent for both convergence-perpendicular (i.e., α is 0°; model 11) and oblique passive margin (i.e., α is 7.5°and 15°; models 12-13). ...

Pre-collisional extension of microcontinental terranes by a subduction pulley