scholarly journals The effect of obliquity on temperature in subduction zones: insights from 3D numerical modeling

2018 ◽  
Author(s):  
Alexis Plunder ◽  
Cédric Thieulot ◽  
Douwe J. J. van Hinsbergen
Keyword(s):  
Subduction Zones ◽  
Mantle Wedge ◽  
Numerical Models ◽  
Mantle Flow ◽  
Mathematical Function ◽  
3D Numerical Modeling ◽  
Plate Interface ◽  
Geological Record ◽  
Parallel Component ◽  
Central Turkey

Abstract. In subduction zones the geotherm is thought to vary as a function of the subduction rate and the age of the subducting lithosphere. Along a single subduction zone the rate of subduction can strongly vary due to changes in the angle between the trench and the plate convergence vector, namely the subduction obliquity. We currently observe such a configuration all around the Pacific (e.g. Marianna, Chile, Aleutians). Subduction obliquity is also supposed in the geological record of Western and Central Turkey. In order to investigate this effect, we designed and computed simple thermo-kinematic finite element 3D numerical models. We prescribe the trench geometry by means of a simple mathematical function and compute the mantle flow in the mantle wedge only by solving the equation of mass and momentum conservation. We then solve the energy conservation equation until steady-state is reached. We analyse the results (i) in terms of mantle wedge flow with emphasis on the trench-parallel component and (ii) in terms of temperature along the plate interface by means of maps and depths-temperature path at the interface. We show that the effect of the trench curvature on the geotherm is substantial. A small obliquity yields a small but not negligible trench parallel mantle flow leading to differences of 50 °C along strike of the model. With increasing obliquity, the trench parallel component of the velocity consequently increases and the temperature variation can be as important as 200 °C along strike. This can even be larger with varying plate velocity. Finally, we discuss the implication of our simulations for the ubiquitous oblique systems that are observed on Earth, the limitation of our modeling approach and the significance for the geological record with an emphasis on the case study of Western and Central Turkey.

scholarly journals The effect of obliquity on temperature in subduction zones: insights from 3-D numerical modeling

Solid Earth ◽  
2018 ◽  
Vol 9 (3) ◽  
pp. 759-776 ◽  
Author(s):  
Alexis Plunder ◽  
Cédric Thieulot ◽  
Douwe J. J. van Hinsbergen
Keyword(s):  
Subduction Zone ◽  
Temperature Variation ◽  
Subduction Zones ◽  
Mantle Wedge ◽  
Numerical Models ◽  
Mantle Flow ◽  
Mathematical Function ◽  
Western Turkey ◽  
Parallel Component ◽  
Temperature Contrast

Abstract. The geotherm in subduction zones is thought to vary as a function of the subduction rate and the age of the subducting lithosphere. Along a single subduction zone the rate of subduction may strongly vary due to changes in the angle between the trench and the plate convergence vector, i.e., the subduction obliquity, due to trench curvature. We currently observe such curvature in, e.g., the Marianas, Chile and Aleutian trenches. Recently, strong along-strike variations in subduction obliquity were proposed to have caused a major temperature contrast between Cretaceous geological records of western and central Turkey. We test here whether first-order temperature variation in a subduction zone may be caused by variation in the trench geometry using simple thermo-kinematic finite-element 3-D numerical models. We prescribe the trench geometry by means of a simple mathematical function and compute the mantle flow in the mantle wedge by solving the equation of mass and momentum conservation. We then solve the energy conservation equation until steady state is reached. We analyze the results (i) in terms of mantle wedge flow with emphasis on the trench-parallel component and (ii) in terms of temperature along the plate interface by means of maps and the depth–temperature path at the interface. In our experiments, the effect of the trench curvature on the geotherm is substantial. A small obliquity yields a small but not negligible trench-parallel mantle flow, leading to differences of 30 °C along-strike of the model. Advected heat causes such temperature variations (linked to the magnitude of the trench-parallel component of velocity). With increasing obliquity, the trench-parallel component of the velocity consequently increases and the temperature variation reaches 200 °C along-strike. Finally, we discuss the implication of our simulations for the ubiquitous oblique systems that are observed on Earth and the limitations of our modeling approach. Lateral variations in plate sinking rate associated with curvature will further enhance this temperature contrast. We conclude that the synchronous metamorphic temperature contrast between central and western Turkey may well have resulted from reconstructed major variations in subduction obliquity.

Plate speeds modulated by sediment subduction: insights from numerical models

2020 ◽  
Author(s):  
Whitney Behr ◽  
Adam Holt ◽  
Thorsten Becker ◽  
Claudio Faccenna
Keyword(s):  
Subduction Zones ◽  
Convergence Rates ◽  
Numerical Models ◽  
Finite Width ◽  
Dynamic Topography ◽  
Plate Interface ◽  
Interface Models ◽  
Low Viscosity ◽  
Uniform Interface ◽  
Sinking Velocities

<p>Tectonic plate velocities predominantly result from a balance between the potential energy change of the subducting slab and viscous dissipation in the mantle, bending lithosphere, and slab–upper plate interface. A range of observations suggest that slabs may be weak, implying a more prominent role for plate interface dissipation than previously thought. Behr & Becker (2018) suggested that the deep interface viscosity in subduction zones should be strongly affected by the relative proportions of sedimentary to mafic rocks that are subducted to depth, and that sediment subduction should thus facilitate faster subduction plate speeds. Here we use fully dynamic 2D subduction models built with the code ASPECT to quantitatively explore how subduction interface viscosity influences: a) subducting plate sinking velocities, b) trench migration rates, c) convergence velocities, d) upper plate strain regimes, e) dynamic topography, and f) interactions with the 660 km mantle transition zone.  We implement two main types of models, including 1) uniform interface models where interface viscosity and slab strength are systematically varied, and 2) varying interface models where a low viscosity sediment strip of finite width is embedded within a higher viscosity interface. Uniform interface models indicate that low viscosity (sediment-lubricated) slabs have substantially faster sinking velocities prior to reaching the 660, especially for weak slabs, and also that they achieve faster ‘steady state’ velocities after 660 penetration. Even models where sediments are limited to a strip on the seafloor show accelerations in convergence rates of up to ~5 mm/y per my, with convergence initially accommodated by trench rollback and later by slab sinking. We discuss these results in the context of well-documented plate accelerations in Earth’s history such as India-Asia convergence and convergence rate oscillations along the Andean margin.</p><p>References: Behr, W. M., & Becker, T. W. (2018). Sediment control on subduction plate speeds. <em>Earth and Planetary Science Letters</em>, <em>502</em>, 166-173.</p>

Subduction zone seismo-dynamics: how to bridge the gap between long-term subduction dynamics and megathrust seismicity?

2021 ◽  
Author(s):  
Adam Beall ◽  
Fabio A. Capitanio ◽  
Ake Fagereng ◽  
Ylona van Dinther
Keyword(s):  
Stress State ◽  
Subduction Zone ◽  
Subduction Zones ◽  
Large Scale ◽  
Large Earthquake ◽  
Force Balance ◽  
Mantle Flow ◽  
Plate Interface ◽  
Plate Motions

<p>The largest and most devastating earthquakes on Earth occur along subduction zones. Here, long-term plate motions are accommodated in cycles of strain accumulation and release. Episodic strain release occurs by mechanisms ranging from rapid earthquakes to slow-slip and quasi-static creep along the plate interface. Slip styles can vary between and within subduction zones, though it is unclear what controls margin-scale variability. Current approaches to seismo-tectonics primarily relate the stress state and seismogenesis at subduction margins to interface material properties and plate kinematics, constrained by recorded seismic slip, GPS motions and integrated strain. At larger spatio-temporal scales, significant progress has been made towards the understanding of subduction dynamics and emerging self-consistent plate motions, tectonics and stress coupling at plate margins. The margin stress state is ultimately linked to the force balance arising from interactions between the slab, mantle flow and upper plate. These mantle and lithosphere dynamics are thus expected to govern the tectonic regimes under which seismicity occurs. It remains unclear how these longer- and shorter-term perspectives can be reconciled. We review the aspects of large-scale subduction dynamics that control tectonic loading at plate margins, discuss possible influences on the stress state of the plate interface, and summarise recent advances in integrating the earthquake cycle and large-scale dynamics. It is plausible that variations in large-scale subduction dynamics could systematically influence seismicity, though it remains unclear to what degree this interplay occurs directly through the plate interface stress state and/or indirectly, corresponding to variation of other subduction zone characteristics. While further constraints of the geodynamic controls on the nature of the plate interface and their incorporation into probabilistic earthquake models is required, their ongoing development holds promise for an improved understanding of the global variation of large earthquake occurrence and their associated risk.</p>

Uncertainties in the stability field of UHP hydrous phases (10-A phase and phase E) and deep-slab dehydration: potential implications for fluid migration and water fluxes at subduction zones

2020 ◽  
Author(s):  
Nestor G. Cerpa ◽  
José Alberto Padrón-Navarta ◽  
Diane Arcay
Keyword(s):  
Lithospheric Mantle ◽  
Subduction Zones ◽  
Mantle Wedge ◽  
Numerical Models ◽  
Stability Field ◽  
Fluid Migration ◽  
Water Fluxes ◽  
Water Release ◽  
The Stability ◽  
Back Arc

<p>The subduction of water via lithospheric-mantle hydrous phases have major implications for the generation of arc and back-arc volcanism, as well as for the global water cycle. Most of the current numerical models use Perple_X [Connolly et al., 2009] to quantify water release from the slab and subsequent fluid migration in the mantle wedge. At UHP conditions, the phase diagrams generated with this thermodynamic code suggest that the breakdown of serpentine and chlorite leads to the near complete dehydration of the lithospheric mantle before reaching a 200-km depth. Laboratory experiments, however, have observed the stability of the 10-Å phase and the phase E in natural bulk compositions, which may hold moderate amounts of water, beyond the stability field of serpentine and chlorite [Fumagalli and Poli, 2005; Maurice et al., 2018]. Here, using 2D thermo-mechanical models, we explore to what extent the presence of these hydrous phases may favor a deeper subduction of water than those predicted by Perple_X.</p><p>We perform end-member models in terms of slab temperature and thickness of hydrated lithospheric mantle entering at trench. The computed geotherms within the uppermost subducted mantle show that the stability field of mantle hydrous phases around 600-800°C and 6-8 GPa is crucial for predictions of water fluxes. We point out that the lack of systematic experiments at these P-T conditions, as well as the absence of 10-Å and E phases in current thermodynamic databases, prevent accurate estimates of deep water transfers. We nonetheless build a phase diagram based on current experimental constraints that includes approximations of their stability field and qualitatively discuss the potential implications for fluid migration in the back-arc mantle wedge and water fluxes.</p>

scholarly journals The inception of plate tectonics: a record of failure

2018 ◽  
Vol 376 (2132) ◽  
pp. 20170414 ◽  
Author(s):  
Craig O'Neill ◽  
Simon Turner ◽  
Tracy Rushmer
Keyword(s):  
Subduction Zones ◽  
Plate Tectonics ◽  
Initial Conditions ◽  
Numerical Models ◽  
Early History ◽  
Early Earth ◽  
Strong Nonlinearity ◽  
Plate Tectonic ◽  
Geological Record ◽  
History Of

The development of plate tectonics from a pre-plate tectonics regime requires both the initiation of subduction and the development of nascent subduction zones into long-lived contiguous features. Subduction itself has been shown to be sensitive to system parameters such as thermal state and the specific rheology. While generally it has been shown that cold-interior high-Rayleigh-number convection (such as on the Earth today) favours plates and subduction, due to the ability of the interior stresses to couple with the lid, a given system may or may not have plate tectonics depending on its initial conditions. This has led to the idea that there is a strong history dependence to tectonic evolution—and the details of tectonic transitions, including whether they even occur, may depend on the early history of a planet. However, intrinsic convective stresses are not the only dynamic drivers of early planetary evolution. Early planetary geological evolution is dominated by volcanic processes and impacting. These have rarely been considered in thermal evolution models. Recent models exploring the details of plate tectonic initiation have explored the effect of strong thermal plumes or large impacts on surface tectonism, and found that these ‘primary drivers’ can initiate subduction, and, in some cases, over-ride the initial state of the planet. The corollary of this, of course, is that, in the absence of such ongoing drivers, existing or incipient subduction systems under early Earth conditions might fail. The only detailed planetary record we have of this development comes from Earth, and is restricted by the limited geological record of its earliest history. Many recent estimates have suggested an origin of plate tectonics at approximately 3.0 Ga, inferring a monotonically increasing transition from pre-plates, through subduction initiation, to continuous subduction and a modern plate tectonic regime around that time. However, both numerical modelling and the geological record itself suggest a strong nonlinearity in the dynamics of the transition, and it has been noted that the early history of Archaean greenstone belts and trondhjemite–tonalite–granodiorite record many instances of failed subduction. Here, we explore the history of subduction failure on the early Earth, and couple these with insights from numerical models of the geodynamic regime at the time. This article is part of a discussion meeting issue ‘Earth dynamics and the development of plate tectonics'.

scholarly journals Role of warm subduction in the seismological properties of the forearc mantle: An example from southwest Japan

2021 ◽  
Vol 7 (28) ◽  
pp. eabf8934
Author(s):  
Changyeol Lee ◽  
YoungHee Kim
Keyword(s):  
Subduction Zones ◽  
Mantle Wedge ◽  
Numerical Models ◽  
Thermal Structure ◽  
Free Fluid ◽  
Southwest Japan ◽  
Seismic Properties ◽  
Delay Times ◽  
Forearc Mantle ◽  
Nonvolcanic Tremors

A warm slab thermal structure plays an important role in controlling seismic properties of the slab and mantle wedge. Among warm subduction zones, most notably in southwest Japan, the spatial distribution of large S-wave delay times and deep nonvolcanic tremors in the forearc mantle indicate the presence of a serpentinite layer along the slab interface. However, the conditions under which such a layer is generated remains unclear. Using numerical models, we here show that a serpentinite layer begins to develop by the slab-derived fluids below the deeper end of the slab-mantle decoupling interface and grows toward the corner of the mantle wedge along the interface under warm subduction conditions only, explaining the large S-wave delay times in the forearc mantle. The serpentinite layer then allows continuous free-fluid flow toward the corner of the mantle wedge, presenting possible mechanisms for the deep nonvolcanic tremors in the forearc mantle.

scholarly journals Earthquakes track subduction fluids from slab source to mantle wedge sink

2019 ◽  
Vol 5 (4) ◽  
pp. eaav7369 ◽  
Author(s):  
Felix Halpaap ◽  
Stéphane Rondenay ◽  
Alexander Perrin ◽  
Saskia Goes ◽  
Lars Ottemöller ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Mantle Wedge ◽  
Plate Interface ◽  
Earth’S Mantle ◽  
Nucleation Sites ◽  
Fluid Supply ◽  
Subduction Fluids ◽  
Geodynamic Models ◽  
Western Greece ◽  
Source And Sink

Subducting plates release fluids as they plunge into Earth’s mantle and occasionally rupture to produce intraslab earthquakes. It is debated whether fluids and earthquakes are directly related. By combining seismic observations and geodynamic models from western Greece, and comparing across other subduction zones, we find that earthquakes effectively track the flow of fluids from their slab source at >80 km depth to their sink at shallow (<40 km) depth. Between source and sink, the fluids flow updip under a sealed plate interface, facilitating intraslab earthquakes. In some locations, the seal breaks and fluids escape through vents into the mantle wedge, thereby reducing the fluid supply and seismicity updip in the slab. The vents themselves may represent nucleation sites for larger damaging earthquakes.

Petrologic and geochemical role of serpentinite in subduction zones and plate interface domains

2015 ◽  
Vol 37 ◽  
pp. 61-64
Author(s):  
Marco Scambelluri ◽  
Enrico Cannaò ◽  
Mattia Gilio ◽  
Marguerite Godard
Keyword(s):  
Subduction Zones ◽  
Plate Interface

scholarly journals Trans-lithospheric diapirism explains the presence of ultra-high pressure rocks in the European Variscides

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Petra Maierová ◽  
Karel Schulmann ◽  
Pavla Štípská ◽  
Taras Gerya ◽  
Ondrej Lexa
Keyword(s):  
High Pressure ◽  
Numerical Models ◽  
Classical Concept ◽  
Plate Interface ◽  
Ultra High Pressure ◽  
Common Process ◽  
Mountain Belts ◽  
Collisional Orogens ◽  
Rock Association ◽  
European Variscides

AbstractThe classical concept of collisional orogens suggests that mountain belts form as a crustal wedge between the downgoing and overriding plates. However, this orogenic style is not compatible with the presence of (ultra-)high pressure crustal and mantle rocks far from the plate interface in the Bohemian Massif of Central Europe. Here we use a comparison between geological observations and thermo-mechanical numerical models to explain their formation. We suggest that continental crust was first deeply subducted, then flowed laterally underneath the lithosphere and eventually rose in the form of large partially molten trans-lithospheric diapirs. We further show that trans-lithospheric diapirism produces a specific rock association of (ultra-)high pressure crustal and mantle rocks and ultra-potassic magmas that alternates with the less metamorphosed rocks of the upper plate. Similar rock associations have been described in other convergent zones, both modern and ancient. We speculate that trans-lithospheric diapirism could be a common process.

Advanced Virtual Prototyping of Axial Piston Machines

2016 ◽  
Author(s):  
Rene Chacon ◽  
Monika Ivantysynova
Keyword(s):  
Numerical Models ◽  
Virtual Prototyping ◽  
Valve Plate ◽  
Cylinder Block ◽  
Plate Interface ◽  
Design And Optimization ◽  
Swash Plate ◽  
Axial Piston Machine ◽  
Axial Piston ◽  
Plate Type

This paper explains how a combination of advanced multidomain numerical models can be employed to design an axial piston machine of swash plate type within a virtual prototyping environment. Examples for the design and optimization of the cylinder block/valve plate interface are presented.

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