scholarly journals Numerical models of trench migration in continental collision zones

2012 ◽  
Vol 4 (1) ◽  
pp. 429-458 ◽  
Author(s):  
V. Magni ◽  
J. van Hunen ◽  
F. Funiciello ◽  
C. Faccenna
Keyword(s):  
Subduction Zone ◽  
Plate Tectonics ◽  
Numerical Models ◽  
Continental Collision ◽  
Force Balance ◽  
Dip Angle ◽  
External Forces ◽  
Stress Dependent ◽  
Subduction System ◽  
Intrinsic Feature

Abstract. Continental collision is an intrinsic feature of plate tectonics. The closure of an oceanic basin leads to the onset of subduction of buoyant continental material, which slows down and eventually stops the subduction process. We perform a parametric study of the geometrical and rheological influence on subduction dynamics during the subduction of continental lithosphere. In 2-D numerical models of a free subduction system with temperature and stress-dependent rheology, the trench and the overriding plate move self-consistently as a function of the dynamics of the system (i.e. no external forces are imposed). This setup enables to study how continental subduction influences the trench migration. We found that in all models the trench starts to advance once the continent enters the subduction zone and continues to migrate until few million years after the ultimate slab detachment. Our results support the idea that the trench advancing is favoured and, in part provided by, the intrinsic force balance of continental collision. We suggest that the trench advance is first induced by the locking of the subduction zone and the subsequent steepening of the slab, and next by the sinking of the deepest oceanic part of the slab, during stretching and break-off of the slab. The amount of trench advancing ranges from 40 to 220 km and depends on the dip angle of the slab before the onset of collision.

scholarly journals Numerical models of slab migration in continental collision zones

Solid Earth ◽  
2012 ◽  
Vol 3 (2) ◽  
pp. 293-306 ◽  
Author(s):  
V. Magni ◽  
J. van Hunen ◽  
F. Funiciello ◽  
C. Faccenna
Keyword(s):  
Subduction Zone ◽  
Plate Tectonics ◽  
Numerical Models ◽  
Continental Collision ◽  
Force Balance ◽  
Small Scale ◽  
Dip Angle ◽  
External Forces ◽  
Stress Dependent ◽  
Subduction System

Abstract. Continental collision is an intrinsic feature of plate tectonics. The closure of an oceanic basin leads to the onset of subduction of buoyant continental material, which slows down and eventually stops the subduction process. In natural cases, evidence of advancing margins has been recognized in continental collision zones such as India-Eurasia and Arabia-Eurasia. We perform a parametric study of the geometrical and rheological influence on subduction dynamics during the subduction of continental lithosphere. In our 2-D numerical models of a free subduction system with temperature and stress-dependent rheology, the trench and the overriding plate move self-consistently as a function of the dynamics of the system (i.e. no external forces are imposed). This setup enables to study how continental subduction influences the trench migration. We found that in all models the slab starts to advance once the continent enters the subduction zone and continues to migrate until few million years after the ultimate slab detachment. Our results support the idea that the advancing mode is favoured and, in part, provided by the intrinsic force balance of continental collision. We suggest that the advance is first induced by the locking of the subduction zone and the subsequent steepening of the slab, and next by the sinking of the deepest oceanic part of the slab, during stretching and break-off of the slab. These processes are responsible for the migration of the subduction zone by triggering small-scale convection cells in the mantle that, in turn, drag the plates. The amount of advance ranges from 40 to 220 km and depends on the dip angle of the slab before the onset of collision.

scholarly journals Effects of basal drag on subduction dynamics from 2D numerical models

2020 ◽  
Author(s):  
Lior Suchoy ◽  
Saskia Goes ◽  
Benjamin Maunder ◽  
Fanny Garel ◽  
Rhodri Davies
Keyword(s):  
Numerical Models ◽  
Force Balance ◽  
Plate Motion ◽  
Mantle Flow ◽  
Plate Motions ◽  
Flow Models ◽  
Plate Size ◽  
Modelling Studies ◽  
Subduction System

Abstract. Subducting slabs are an important driver of plate motions, yet the force balance governing subduction dynamics remains incompletely understood. Basal drag has been proposed to be a minor contributor to subduction forcing, because of the lack of correlation between plate size and velocity in observed and reconstructed plate motions. Furthermore, in single subduction system models, low basal drag, associated with a low ratio of asthenospheric to lithospheric viscosity, leads to subduction behaviour most consistent with the observation that trench migration velocities are generally low compared to convergence velocities. By contrast, analytical calculations and global mantle flow models indicate basal drag can be substantial. In this study, we revisit this problem by examining the drag at the base of the lithosphere, for a single subduction system, in 2D models with a free trench and composite non-linear rheology. We compare the behaviour of short and long plates for a range of asthenospheric and lithospheric rheologies. We reproduce results from previous modelling studies, including low ratios of trench over plate motions. However, we also find that any combination of asthenosphere and lithosphere viscosity that produces Earth-like subduction behaviour leads to a correlation of velocities with plate size, due to the role of basal drag. By examining Cenozoic plate motion reconstructions, we find that slab age and plate size are positively correlated: higher slab pull for older plates tends to be offset by higher basal drag below these larger plates. This, in part, explains the lack of plate velocity-size correlation in observations, despite the important role of basal drag in the subduction force-balance.

Vertically Driven Dynamics and Magmatism of Rapid Subduction Initiation in the Western Pacific

2020 ◽  
Author(s):  
Ben Maunder ◽  
Saskia Goes ◽  
Julie Prytulak ◽  
Mark Reagan
Keyword(s):  
Plate Tectonics ◽  
Numerical Models ◽  
Plate Boundaries ◽  
Temporal And Spatial Distribution ◽  
Subduction Initiation ◽  
Primary Driver ◽  
International Ocean Discovery Program ◽  
Subduction System ◽  
The Western Pacific

<p><strong>Plate tectonics requires the formation of plate boundaries. Particularly important is the enigmatic initiation of subduction: the sliding of one plate below the other, and the primary driver of plate tectonics. A continuous, in situ record of subduction initiation was recovered by the International Ocean Discovery Program Expedition 352, which drilled a segment of the fore-arc of the Izu-Bonin-Mariana subduction system, revealing a distinct magmatic progression with a rapid timescale (</strong><strong>approximately 1 </strong><strong>million years). Here, using numerical models, we demonstrate that these observations cannot be produced by previously proposed horizontal external forcing. Instead a geodynamic evolution that is dominated by internal, vertical forces produces both the temporal and spatial distribution of magmatic products, and progresses to self-sustained subduction. Such a primarily internally driven initiation event is necessarily whole-plate scale and the rock sequence generated (also found along the Tethyan margin) may be considered as a smoking gun for this type of event. </strong></p>

scholarly journals Effects of basal drag on subduction dynamics from 2D numerical models

Solid Earth ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 79-93
Author(s):  
Lior Suchoy ◽  
Saskia Goes ◽  
Benjamin Maunder ◽  
Fanny Garel ◽  
Rhodri Davies
Keyword(s):  
Numerical Models ◽  
Force Balance ◽  
Plate Motion ◽  
Mantle Flow ◽  
Plate Motions ◽  
Flow Models ◽  
Plate Size ◽  
Modelling Studies ◽  
Subduction System

Abstract. Subducting slabs are an important driver of plate motions, yet the relative importance of different forces in governing subduction motions and styles remains incompletely understood. Basal drag has been proposed to be a minor contributor to subduction forcing because of the lack of correlation between plate size and velocity in observed and reconstructed plate motions. Furthermore, in single subduction system models, low basal drag leads to subduction behaviour most consistent with the observation that trench migration velocities are generally low compared to convergence velocities. By contrast, analytical calculations and global mantle flow models indicate basal drag can be substantial. In this study, we revisit this problem by examining the drag at the base of the lithosphere, for a single subduction system, in 2D models with a free trench and composite non-linear rheology. We compare the behaviour of short and long plates for a range of asthenospheric and lithospheric rheologies. We reproduce results from previous modelling studies, including low ratios of trench over plate motions. However, we also find that any combination of asthenosphere and lithosphere viscosity that produces Earth-like subduction behaviour leads to a correlation of velocities with plate size, due to the role of basal drag. By examining Cenozoic plate motion reconstructions, we find that slab age and plate size are positively correlated: higher slab pull for older plates tends to be offset by higher basal drag below these larger plates. This, in part, explains the lack of plate velocity–size correlation in observations, despite the important role of basal drag in the subduction force balance.

THE EVOLUTION OF CONTINENTAL COLLISION CONTROLLED BY THE WIDTH OF ADJACENT SUBDUCTION ZONE

2018 ◽  
Author(s):  
David Willis ◽  
◽  
Peter Betts ◽  
Louis Moresi ◽  
Laurent Ailleres ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Continental Collision

Analysis of TBM Tunnel Behavior in Jointed Rock Mass

2011 ◽  
Vol 90-93 ◽  
pp. 2033-2036 ◽  
Author(s):  
Jin Shan Sun ◽  
Hong Jun Guo ◽  
Wen Bo Lu ◽  
Qing Hui Jiang
Keyword(s):  
Rock Mass ◽  
Numerical Models ◽  
Jointed Rock ◽  
In Situ Stress ◽  
Jointed Rock Mass ◽  
Joint Orientation ◽  
Joint Spacing ◽  
Factors Affecting ◽  
Dip Angle

The factors affecting the TBM tunnel behavior in jointed rock mass is investigated. In the numerical models the concrete segment lining of TBM tunnel is concerned, which is simulated as a tube neglecting the segment joint. And the TBM tunnel construction process is simulate considering the excavation and installing of the segment linings. Some cases are analyzed with different joint orientation, joint spacing, joint strength and tunnel depth. The results show that the shape and areas of loosing zones of the tunnel are influenced by the parameters of joint sets and in-situ stress significantly, such as dip angle, spacing, strength, and the in-situ stress statement. And the stress and deformation of the tunnel lining are influenced by the parameters of joint sets and in-situ stress, too.

scholarly journals Towards community-driven paleogeographic reconstructions: integrating open-access paleogeographic and paleobiology data with plate tectonics

2013 ◽  
Vol 10 (3) ◽  
pp. 1529-1541 ◽  
Author(s):  
N. Wright ◽  
S. Zahirovic ◽  
R. D. Müller ◽  
M. Seton
Keyword(s):  
Ocean Circulation ◽  
Plate Tectonics ◽  
Numerical Models ◽  
Plate Motion ◽  
Temporal Data Mining ◽  
Dynamic Topography ◽  
Southeastern Australia ◽  
Eastern Australia ◽  
Spatio Temporal ◽  
Fossil Data

Abstract. A variety of paleogeographic reconstructions have been published, with applications ranging from paleoclimate, ocean circulation and faunal radiation models to resource exploration; yet their uncertainties remain difficult to assess as they are generally presented as low-resolution static maps. We present a methodology for ground-truthing the digital Palaeogeographic Atlas of Australia by linking the GPlates plate reconstruction tool to the global Paleobiology Database and a Phanerozoic plate motion model. We develop a spatio-temporal data mining workflow to validate the Phanerozoic Palaeogeographic Atlas of Australia with paleoenvironments derived from fossil data. While there is general agreement between fossil data and the paleogeographic model, the methodology highlights key inconsistencies. The Early Devonian paleogeographic model of southeastern Australia insufficiently describes the Emsian inundation that may be refined using biofacies distributions. Additionally, the paleogeographic model and fossil data can be used to strengthen numerical models, such as the dynamic topography and the associated inundation of eastern Australia during the Cretaceous. Although paleobiology data provide constraints only for paleoenvironments with high preservation potential of organisms, our approach enables the use of additional proxy data to generate improved paleogeographic reconstructions.

Seismic mantle anisotropy associated with subduction polarity reversal: Insights from numerical models

2020 ◽  
Author(s):  
Jan Philipp Kruse ◽  
Harro Schmeling ◽  
Frederik Link ◽  
Georg Ruempker
Keyword(s):  
Seismic Anisotropy ◽  
Numerical Models ◽  
Eastern Alps ◽  
Continental Collision ◽  
Polarity Reversal ◽  
Oceanic Plate ◽  
Grid Points ◽  
Dependent Flow ◽  
Mantle Anisotropy ◽  
The Right

<p>The deep dynamics of continental collision is one of the least understood plate tectonic processes. One interesting process that is believed to be a feature of continental collision is a flip in subduction polarity. A prominent location where such a flip is proposed by different seismic tomography studies (e.g Kissling et al., 2006) are the eastern alps.</p><p>The aim of our study is to find a particular signature in the seismic anisotropy of the upper mantle that is the result of a temporal subduction polarity reversal. In our case the seismic anisotropy is produced by the LPO of mantle minerals due non-Newtonian deformation rates.</p><p>We use the thermo-mechanical 2D finite-difference code FDCON which has been extended to include a free surface with an erosion/sedimentation mechanism. For the geometrical setup an oceanic plate is placed between two continental plates. Subduction of the oceanic plate beneath the right continent is prescribed. The overriding plate (right) is pushed by constant kinematic boundary conditions. Among other parameters we varied a) the plastic strength of sediments (very weak to strong), b) the ductile rheology of the lower crust (felsic or mafic) and c) the convergence velocity of the two continents (1 - 10 cm/yr). From our results we can identify at least two different mechanisms for a subduction polarity switch.</p><p>To estimate the full elastic tensor at the grid points of interest, we use a modified version of DREX (Kaminski et al., 2004) that can handle a time dependent flow field. Using the full elastic tensors, we can calculate, e.g with MSAT (Walker & Wookey, 2012), effective delay times and fast shear wave polarization directions for arbitrary azimuths.</p><p>Our first results show significant differences between models with and without a subduction polarity reversal.</p>

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